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mer (lf THE ds 


QUARTERLY JOURNAL 


OF THE 


GEOLOGICAL SOCIETY OF LONDON. 


EDITED BY 


THE ASSISTANT-SECRETARY OF THE GEOLOGICAL SOCIETY. 


Quod si cui mortalium cordi et cure sit non tantum inventis herere, atque iis uti, sed ad ulteriora 
penetrare; atque non disputando adversarium, sed opere naturam viucere; denique non belle et probabiliter 
Opinari, sed certo et ostensive scire; tales, tanquam veri scientiarum filii, nobis (si videbitur) se adjurgant. 
—Novum Organum, Prefatio. 


5 
P 


64S) 

y 
Sis TEA muse 
LONDON: : 


LONGMANS, GREEN, AND CoO. 


PARIS: CHARLES KLINCKSIECK, 11 RUE DE LILLE. 
LEIPZIG: T.0.WEIGEL, 


SOLD ALSO AT THE APARTMENTS OF THE SOCIETY. ° 


| MDCCCXCIX. 


~~ 2s 


List 
OF THE 


OFFICERS 


OF THE 


GEOLOGICAL SOCIETY OF LONDON. 


RARRARARALDIIIIIONN 


Elected February 17th, 1899. 


Vv POS ISIIS as 


President, 
W. Whitaker, Esq., B.A., F.R.S. 
Wice-Prestvents. 
Henry Hicks, M.D., F.B.S. Prof.W.J.Sollas, M.A., D.Se.,LL.D., F.R.S. 
Prof. J. W. Judd, C.B., LL.D., F.R.S. | Rev. H. H. Winwood, M.A. 
Secretaries. 
R. 8. Herries, Esq., M.A. | Prof. W. W. Watts, M.A. 


Foretqu Secretary. 
Sir John Evans, K.O.B., D.C.L., LL.D., F.R.S., F.L.S. 


Creasurer, 
W. T. Blanford, LL.D., F.R.S. 


COUNGIL, 


W. T. Blanford, LL.D., F.R.S. Prof. J. W. Judd, C.B., LL.D., F.B.S8. 
Prof. T. G. Bonney, D.Se., LL.D., F.R.S. | H. W. Monckton, EKsq., F.L.S. 
Sir John Evans, K.C.B., D.C.L., LL.D., | F. W. Rudler, Esq. 


E.R.S., F.L.S. Prof. H. G. Seeley, F.R.S. 
HK. J. Garwood, Esq., M.A. A. O. Seward, Esq., M.A., F.R.S. 
J. W. Gregory, D.Sc. Prof. W. J. Sollas, M.A., D.Sc., LL.D., 
Alfred Harker, Esg., M.A. F.B.S. 
F. W. Harmer, Esq. A. Strahan, Esq., M.A. 
R. S. Herries, Esq., M.A. Prof. W. W. Watts, M.A. 
Henry Hicks, M.D., F.R.S. W. Whitaker, Hsq., B.A., F.R.S. 
Rey. Edwin Hill, M.A. Rev. H. H. Winwood, M.A. 
G. J. Hinde, Ph. D., E.R.S. A. S. Woodward, Esq., F.L.S. 


W.H. Hudleston, Esq., M.A., F.R.S.,F.L.S. 


Assistant-Decretary, Clerk, Librarian, anv Curator. 
L.. L.. Belinfante, M.Sc. 


Assistants in Office, Library, and fMuseum. 
W. Rupert Jones. | Clyde H. Black. 


TABLE OF CONTENTS. 


Arnoup-Bemrosr, H. H., Esq. Geology of the Ashbourne & 
Buxton Branch of the London & North-western Railway : 


Ashbourne to Crake Low. (Plates XVII & XVIIL)........ 224 
On a Sill and Faulted Inlier in Tideswell Dale, Derby- 
Bren alfa besya mM rae OMA) tse saicaids loeb edee coe ewe es 239 


On the Petrography of the Rocks of Congleton Edge .... 556: 


Bonney, Prof. T. G., & Miss C. A. Ratstn. On Varieties of Ser- 
pentine and Associated Rocks in Anglesey. (Plate XXIII.) .. 276 


, & the Rev. Epwin Hixz. Relations of the Chalk and Drift 
riral AUUCCeT es VG Ihe CT KOxS) TER AS ee ea cr Om oe ee eran ee 305: 


Buckman, 8.8., Esq. Gravel at Moreton-in-the-Marsh, G!oucester- 
SBME Cr CEOSTFAEL:)) Aye hed mbar eit Powe tia -alae Wielka ele S's wes 220: 


CroveHn, C.T., Esq., & Dr. W. Pottarp. On Spinel and Forsterite 
from the Glenelg Limestone (Inverness-shire) .............. 372 


Cots, Prof. Grenvittr A. J. On the Age of certain Granites in 
the Counties of Tyrone and Londonderry .............-. fee dew 


Daxyns, J. R., Esq. The Limestone-knolls below Skipton and 
Gr assington MUG HANCLS kel ot Meike xe in yl a etate costa eeKaay Oth « Soles oye oa 359 


Davin, Prof. T. W. Epczworrtn, & EK. F. Prrrman, Esq. On the 
Paleozoic Radiolarian Rocks of New South Wales. (Plates II- 
VARS tes homer ene aly rela Say srene’ = oie Sage la abe ic) « wield cimtaia.n mmels 16 


DonaLp, Miss JANE. Remarks on the Genera Ectomaria, Koken, 


and. Hormotoma, Salter, with Descriptions of British uw 
(ENE. SLs eho OU Lag) eee MRS Re A RAT 08 ee 251 


Garwoop, E. J., Esq. Additional Notes on the Glacial Pheno- 
~ mena of Spitsbergen. (Plates XLI-XLVIIL.).............. 681 


Gipson, WaLcoT, Esq., & Dr. WaEELTon Hinp, On the Agglo- 
merates and Tufts in the Carboniferous Limestone Series of 
Wo mmle come die grit sini panies ks tM WWE KLE EA RRA DEE bak aoe 1. 048 


lV TABLE OF CONTENTS. 


Page 
CoBpoON, irs, eSeeOcun vin eMiss "WOM... sss... ocd on oe ee 560 


Groom, Prof. T. T. The Geological Structure of the Southern 
Malverns, and of the Adjacent District to the West. (Plates 


PRO NIV ei eee ians als, coer AeA Be Dake oo at oh A 129 
Harrison, Prof. J. B., & A.J. Juxzs-Brownsz, Esq. The Oceanic 

Deposits of Trinidad (British West Indies)». 5/5. ....23. oer 177 
Hirt, the Rev. Epwin, & Prof. T.G. Bonney. Relations of the 

Chalk-and Drittan Mioenvand jumen 4) 57 acc. a. ee eee 305 


Hitt, J. B., Esq. On the Progressive Metamorphism of some 
Dalradian Sediments in the Region of Loch Awe............ 470 


Hinp, Dr. WHEEriton. On Three new Species of Lamellibranchiata 
from the Carboniferous Rocks of Great Britain. (Plate XXV.) 365 


, & Watcot Gipson, Esq. On the Agelomerates and Tuffs 
‘in the Carboniferous Limestone Series of Congleton Edge .... 548 


Hinpg, Dr. G. J. On the Radiolaria in the Devonian Rocks of New 
South’ Wales; (Plates VIM & EXO) ook eye 2 a 38 


. On Radiolaria in Chert from Chypons Farm, Mullion 
Parish, Cornwall.) (Plate X6Vi.) 225 28) 2 Pee oe ee eee 214 


Hoiuanp, Puinip, Esq. Analyses of Hauraki Rhyolites ........ 467 


JENNINGS, A. VAUGHAN, Esq. The Geology of the Davos District, 
Switzerland. (Plates KOVAL oe XK XQVaLIE) ieee ly seat an eeame 381 


JukEs-Browng, A. J., Esq., & Prof. J.B. Harrison. The Oceanic 
Deposits of Tiinidad (British West Indies). (25.2) see seer Ae 


Kane, W. Wickuam, Esq. The Permian Conglomerates of the 
lower Severn Basin.” (Plates Xi & XI) 23.00. De 


Marr, J. E., Esq. Note on a Conglomerate near Melmerby (Cum- 
erlang). 3 ex ea 3 gears ghana ena a heen ieee ae ree TL 


. On Limestone-knolls in the Craven District of Yorkshire 
and Hlsewhere. (Plate XXIV.) ...... wel aiode Ode katana ea 327 


Martuey, C. A., Esq. On the Geology of Northern Anglesey .... 635 


Newron, E. T., Esq. On the Remains of Ama from Oligocene 


Strata in the Isle of Wight.: (Plate iy ace ae ee: ee 1 
On a Megalosauroid Jaw from Rheetic Beds near Bridgend, 
Glamore anshire. (Plate: Ae) ores ent ee dee Sera tlel se aren oe 89 
Additional Notes on the Vertebrate Fauna of the Rock- 
fissure at Ightham, Kent. (Plate XXVIII.) ................ 419 


OGILVIE, Miss M. M. [Mrs. Gorpon]. The Torsion-Structure of 
the Dolomites, (Plate XTi). 07 Wie iaae eeeeeein ae 560 


Park, JAMES, Esq., & F. Rurtey, Esq. Notes on the Rhyolites of 
the Hauraki Goldfields, New Zealand. (Plates XXXI- 
XIN) aie ie Cathet Sta auacn 4 wR ete ne ee Be ie ae 449 


/ 


TABLE OF CONTENTS. 


Parkinson, JoHN, Esq. On an Intrusion of Granite into Diabase 
at Sorel Point, Northern Jersey. (Plates XXIX & XXX.) 


Pittman, E. F., Esq., & Prof. T. W. EpGzwortH Davip. On the 
Paleozoic Radiolarian Rocks of New South Wales. (Plates 
II-VII.) 


PotiarD, Dr. W., & C. T. Clovueu, Esq. Oa Spinel and Forsterite 
from the Glenelg Limestone (Inverness-shire) 


eeoeceeee see eee ee sce se eee eee ee er ere ee ewe wee e eee eee Fee 


eevee et eee ee ee ® 


Rats1n, Miss C. A., & Prof. T.G. Bonnzy. On Varieties of Ser- 


pentine and Associated Rocks in Anglesey. (Plate XXIIL) .. : 


Reep, F. R. Cowper, Hsq. The Lower Paleozoic Bedded Rocks 
a Vounty Wateriord, (Plate SUD) 0 Fhe av onesie ew ne cy 
Rowe, Dr. A. W. An Analysis of the Genus Micraster, as deter- 
mined by rigid zonal coilecting from the Zone of Rhynchonella 
Cuviert to that of Micruster cor-anguinum, (Plates XXX V- 
BONEN SNS de cc N ot ce Mabe tua MLM he Me rd Sia ava: oes Adalat el 


Rutty, Frank, Esq. On a Small Section vf Felsitic Lavas and 
‘Tuffs near Conway (Caernarvoushire) 


eeevrree eee eer ee ereoee eevee 


,& J. Park, Esq. Notes on the Rhyolites of the Hauraki 
Goldtields, New Zealand. (Plates XXXI-XXXIV.) ........ 
Satter, A. E., Esq. On the Occurrence of Pebbles of Schorl-rock 
from the South-west of England in the Dritt-deposits of Southern 
and Eastern England. (Adstract.) 


ere e eee ee ee ee woe we ee we ew 


Seexey, Prof.H.G. On the Distal End of a Mammalian Humerus 
trom Tonbridge (Hemromus major) 


On Evidence of a Bird from the Wealden Beds of Ansty 
Lane, near Cucktield 


ore ere oe ee we ee esr eae ere ere ee ee ee sess eeeee 


Sorxas, Prof. W. J. Fossils in the University Museum, Oxford: 
I. On Silurian Echinoidea aud Ophiuroidea 


voereee eee ee se eone 


On the Occurrence of Sponge-spicules in the Carboniferous 
Limestone of Derbyshire 


ae 6 66 @ 6 6 see C8 pe 8 8 we 8 wg oe es ote et 


TuHompson, BrrBy, Esq. Geology of the Great Central Railway : 
Hirne avon ALCS Dy, tae. aie acetone baie atten uisinis ln losis n « Wales's acid 6 o's 


Tuomson, the late JosrpH. The Geology of Southern Morocco 
and the Atlas Mountains 


Warts, Prof. W. W. On the Microscopic Study of some of the 
atks ot NOrsmern ANOLESCY 2 claw oc oe wets ne vies win v ei slate oe © 


PROCEEDINGS. 
Proceedings of the Meetings 
Amma EepOrt: sous. gee ere nes ee 


List of Donors to the Library 


eoceseeevres ere @ Fever eoveeee* Fe eevee s 


Vi 


Page 


. 430 


494 


170 


1x 


XV 


V1 TABLE OF CONTENTS. 


Page 
Iistcot Moreign\Memipers ). aged scission alps 64s os 6 site clewlovwe KXV 
List of Boreien Cotrespondemts, i). 2ciee sacs sos e oon ee XXVI1 
lhastiot Wollaston Medalists. 21.4 lke Sybinigl« seis e eu cee ha pian xxvii 
Kiet of Muxchison Medallists, 4.5.00 s/oce% oe a5 nec oes oes oe Kise 
hist rot: Mivell Medalists ye. ios « feutieis cae oie usre pers a srahing XXX 
istiol Bissby Medallists: . .. ki .%.hc gurus othe ss oe oe ae XXX1 
Applications of the Barlow-Jameson Fund .................. XXX1 
inaneiad Ave port. 5 o'y chajsaaein eto ele aie sews clanoegetinia akteerares XXxil 
Award of the Medals and Proceeds of Funds ................ XXKIX 
PAMDUVOTSATY “A CAMCES 5.06 up eis @ pains Peep ele bees vale eee hii 
Bartuer, F. A., Esq. On Pyramid-pebbles or ‘ Dreikanter’ .. xe 
BavERMAN, H., Esq. On the Gellivaara and Kiirunavaara 
Imon-ores Deposits < chats <ice pp phe uiies Haat e eek Geen i 
Davirs, A. M., Esq. On Glauconitic Limestone from the 
Iinaremdore: Olay As Fgh Oc ce content Nc Pence oe peer eae Ixxxvii 
Gerxre, Sir A. On Pseudo-fossils from the Silurian of Tipperary il 
Hinpg, Dr. G. J. On Devonian Rock-specimens from New 
Sout VV aes oleic w dite anes Wee ee 15 hee geies on See ee a li 
SEELEY, Prof. H. G. On-.a Monotreme Footprint from the 
AR GiAS*OL SPOUNCON oo.) s:e a sents eyed eee ek cick eos ae xxi 
SrirFr, Capt. A. W. On a Miocene Cardium(?) from the 
MalwanWoaet: 2.0 os tiie e acten See von etee aie arene v1 


WatLForD, E. A. On some Ironstone Fossil Nodules of the 
Ties’ < (Tutte tonty 2) ceo ener ers soc he oes eae XCll 


Woop, J. G., Esq. On Fossil Oak from Chepstow eg lv 


LIST OF THE FOSSILS DESCRIBED AND FIGURED 
IN THIS VOLUME. 


Name of Species. Formation. Locality. Page 
BELowsEa. 

Spherozoum,sp. Pl. viii, figs. la-e| Devonian......... | New South Wales} 43 
SPH#ROIDEA. 


Acanthosphera australis, sp. nov. 


TRL a y 
ee Btheridgei, gp. nov. Pl. viii, Devonian ...... New South Wales, 

Bee Bete cas onic tg «cus banerane 49 

ele 
ic abe nana, sp. nov. Fl-xvi,! | Ordovician (?)...| Mullion Parish...) 215 
Cenosphera affinis, sp. noy. Pl. viii,} \ r¢ as 
scitula,sp.nov. PI. viii, fig. 2 | 43 
Dorysphera echinata, sp. nov.) ! | 

BaD Viti NSS Weve cs vant vat odot te | 45 
Heliosoma echinatum, sp. nov. | 

Be ch tapes: EGG By aco cine dn na dors | 50 

Parone, sp.nov. Pl, ix, fig.3 | | 50 
Heliosphera clavata, sp. nov.) | ! 
RETARD, es DN vases on bea necndenpes 50 
fenestrata, sp. nov. PI. viii, 

BRUNA errs cttcsanenGante sensei ee 49 
ce ee, sp. nov. (PL viii, ‘ Devonian......... New South Wales) 4 49 
—— Tamworthi, sp.nov. PI. viii, | 

hE] Faure ag eS Sees peaeae | 49 
SR a ( 2) sp. ind. PI. viii, | 

eb ae Nan thee Oveeaduatabsece oeka 44 
Bhodosphera Ruesti, sp. nov. | 

Relais Oe os. n ct hatte cere ace 44 
Spongoplegma australe, sp. nov.| | 

PA VER BOI OI o ccecescsbece ous noes | 44 
Staurolonche Davidi, sp. nov.| | 

Eyes ND. osach can veconsn es xe | 46 

laterna, sp. nov. Pl. viii, 
BND oe odceb nes Sie Fapebee oe sees soe 5 | 47 


Vill FOSSILS DESCRIBED AND FIGURED. 


Name of Species. 


Formati 


on. 


SPHAROIDEA (continued). 


Staurolonche scitula, sp. nov.| | 


Jel, vanity ie eens eee mene 
tenella, sp. Moy. 22). villi, 


Oar einen obliquun, sp. nov. 


Staurosphera (2) ornata, sp. nov. 
el vi, ce ee pr saee a seeeee 
pusilla, Sp. mov. | eh vine 


Stigmosphera echinata, sp. nov. 
IAN MOL echt atiokercGauacnt aes 
Stigmospherostyius inequalis, sp. 


| : 
Bl Ge 17 eae fp PERRI Soesoe 


Ordovician (?)... 


MO Ws Sas Kove en onan er wea ok 
Stylosphera obtusa, sp. nov.) } 
NEVA INO Neds veoie, sais sis oisatea heres 

Trilonche elegans, sp.nov. PI. viii, 

MRO) bac ccipisieidiossaeiisssaclonseeieon 
— Pittman, sp. nov. Pl. viii, 
hier CO GG MA rte eos con Casein ns 
vetusta, gen. et sp. nov. 
XD Oe Orca acecnowan sec see ec’ 


Var. @ noy, Pl. vin, 
Miers UOT nace ene wean s «cece th 
Aiphosphera minaz, sp. nov. 
SPIO val, He (Soa e tasae helettote nce wae V's 


PRUNOIDEA. 


Cenellipsis favosa, sp. nov. Pl. xvi, 
AECL BOs cae hci cower Naceeene en seat 
scitula, sp.nov. Pl. xvi. fig.6 
setosa, sp. nov. PI. xvi, fig. 
Druppalonche clavigera, gen. et sp. 
moy., Pl. xvi; Howe e ec... 
ovata, sp.nov. Pl. xvi, fig. 15 
Eliipsidium castanea, sp. nov. 
He eie HG, A ccc cwcmeeaeeenmacae re 
Ellipsostigma australe, gen. et sp. 
ANOVA M e R, A1G  o ee aaee 
Spongocelia citrewm, sp. nov. 
JENS TS Gy Te Fe PAE Roc eB 
oliva, sp. nov. Pl. ix, fig. 19 
Staurodruppa Foxti, sp. nov. 
Plex, tes, V—13..... cceseeee sees 
— nana, gen. et P nov. Pisa 
HAO cel etcniederc ves'n es pio nuegwa sunere 
— nucula, sp.nov. PI. ix, fig.7 
—— Pl. xvi, figs. 9-10 ... 
prelonga, sp. noy. Pl. ix, fig.6 


, 


NS 


} 


7| } Ordovician (?)... 


\ Devonian ...... 


Ordovician (?) 


Devonian ...... 


Ordovician (?).. 


Devonian 


Locality. 


New South Wales 


Mullion Parish .. 


New South Wales 


Mullion Parish .. 


Page 


47 
47 
47 
46 
46 


| 
: 
ie 


| 45 


( 
| 216 
216 


|4 216 


| 217 
( 218 


' 
51 


New South Wales/{ 51 


.| Mullion Parish ... 


New South Wales 


Mullion Parish ... 
New South Wales 


| 52 
L 52 


217 


FOSSILS DESCRIBED AND FIGURED. 1x 


Name of Species. | Formation. Locality. | Page 
DIscorDEA. 
Distriactis vetusta, sp.nov. Pl. ix,| \ ( 
MMO eee te oe, spc honk saetecacae ts | 53 
Heliosestrum nigrum, sp. nov. | 
An ical Sa ae | 54 
Spongodiscus acinus sp.nov. Pl.ix, | 
Li: NES) at 54 
cribrarius, sp. nov. Pl. ix, | | 
fies WS cde ee | 54 
aaa Puucius, sp. noy. PI, ix, | | 
Pee errr apistivnl as eaiiemptalners | 5+ 
——- scutulatus, sp. nov. Pl. ix,| } Devonian......... New South Wales} < 
BI MPR se Sato aks cunaiocenenaide | 55 
Spongolonche lens, sp. nov. PI. ix, 
ie. ALL) Re A ae ee ae eR ee | 5d 
Spongotripus Senestratus, sp. nov.| ! 
BT IO cscs cee ese | | 55 
patella, sp.nov. Pl. ix, fig. 21] ! 59 
Theodiscus hastatus, sp.nov. Pl. ix,| | | 
ihe | (9) uN es ca Fa ies adie ama a 53 
Triactiscus lanceola, sp.nov. Pl. ix,| | | 
cc, siosrataaseteetatstteen J | 53 
# riod (5mm *P- BY! | Ordovician (2).., Mullion Parish ...._ 218 
Bg. Oren ener f Devonian...) New South Wales) 53 
PLECTOIDEA. 
Plagiacantha australis, sp. nov.| \ ei 
EAU PM 2 es cht aetna de aid once. aver 56 
Plagoniscus colligatus, sp.nov., fig. b | | 56 
—— cristatus, sp. nov., fig. a ...... } Devonian......... New South Wales|{ 56 
simplex, 8p. Nov. Pl. ix, fig. 24} | 56 
— (“) vetustus, sp. nov., fig. Bowel oT 
i) SPs HE. @ icc eaeebsbsaaavenacs J eer 
Mownvicu.rrorip&. 
Monticulipora (Diplotrypa Bae Tramore Lime-| Faure 
Pe ee ee ie | } stone onise.,. | Waterford coast., 763 
EcninoipEa. 
Echinocystis pomum, figs. 12-14 ... (?) (?) 707 
Micraster cor-anguinum. Pls.xxxv-| ) ; 
ROTI ORE as hh se naned none ba 538 
var. latior nov 
He peNe UI ing Seu sce cic oe te sows ot 539 
—— cor-bovis. Pls. xxxv, xxxviii— 
ORI sa neece ch eenkcenmescnace sa WiChalley ca-ceu.ar South of England) { 518 
—-- cor-testudinarium. Pl. xxxv. 534 
Leskeit. Pls. xxxv, xxxvi & 
PK SVT Wa cerees sietlann cee epaiy accu 525 
precursor, nom.  nov.| | | 
IPERS 2.6.4). 0.5. 441 eee ) (530 
Paleodiscus feror, Figs. 6-11 ... (?) (?) 701 
ETOLOCULAT ES! SPs sic oivelets atin -eece ce ...| Upp. Silurian (?)| Leintwardine ...| 709 


FOSSILS DESCRIBED AND FIGURED. 


Name of Species. | Formation. | Locality. Page 
OPHIOCISTIA, ord. nov. 
ae & i ie SP. POY-s! | Tower Ludlow .| Leintwardine ...| 695 
fey agerna, gen. et sp. nov.,| Wenlock Time} \ Aialvern Dist eee 
PE MONO R aid causpactinvcqinw a tewslsees StOMe ......:.. J 
CYsTOIDEA. 
Glyptocystis cf. pennigera  ......... Raheen Shales .| Newtown Head | 762 
Tramore Lime-| | : 
Bes ak ue siajadehiaemereee sels cecteeisaee { Sno meaceoe } Waterford cone 763 
CyYsTOCIDAROIDA. 
i gigas, gen. et sp. nov., | | ee | (?) 700 
TRILOBITA. 
Ampyex cf. Volborthi .......cccpeeeeee a) (745 
Asaphus Haughtoni, sp. nov. PI. 
cea WT (a MR Os 8 es Re neo TiSe ee a 757 
-—— (Ptychopyge ?) radiatus, var. .| + Loner \ Waterford coast.| « 756 
VSP ee teat ao Gt Be ie ee 757 
Calymene brevicapitata .....0...+-++.- 750 
Chetrurus gelasinosus ..........0.0.- ) |_748 
Coe he eae GBD mg, al | Ordovician ain Newtown Head .| 751 
—— sex-tuberculata, sp. nov. Pl.| ( 
alii, ALOU AS) eo enrceey a teas Maem mane | Tramore Lime-| | | 752 
tramorensis. Pl. xlix, fig.6 .|} stone Series...| } Waterford coast.| 4 750 
Enerinurus fallax, sp. nov. Pl.| | is | 
Kl POS COLD |. aeeaketoce eeeeeel: ) J \ 753 
Harpes Hlanagani ........+-<+.+0+++s ei, Ordovician ..-.:: _ Newtown Head .| 745 
Illenus Davisi var. pseudolimbatus| \ } fi 
MOV, 04 ci0. 05 sapien ewe secee wee eelmeneee oe | : 758 
IMCAGIGSPIS, (SP, G25. snsoneppeeweesnee | 700 
PBI au aaron steams tear ere ate ntalep 756 
Phacops Brongniartt..........00.++0- 749 
EC UGL | is eel eee 750 
I MESI 5 eahene ke cera ne See ae : | 749 
truncato-caudatus ......+.4+6- | Tramore Lime- 750 
Remopleurides Portiocki, sp. nov.| { stone Series...| } Waterford coast.| 
Pex lie, A, nos vene eee ae | _| | 746 
Salieri, sp.nov. Pl. xlix, figs. 
SOM era et ss 604) ands seeeece eee eeReRe 747 
— tuberculatus, sp.nov. Pl.xlix, 
EON hcn'evisc yank occ science mete nee 748 
Tramoria punstata, gen. et sp. nov. 
Pivedix) figs. 14-16 ....p.cecvcuecs | 758 
Trinucleus hibernicus .......c.cec00 Raheen Shales .| J \ 744 


FOSSILS DESCRIBED AND FIGURED, Xi 


Name of Species. | Formation. | Locality. | Page 
Pouyzoa. 
ee (Tramore Lime- reo 
Coscinium cf. proavum ..........0000- | stone Tramore Bay ...| 762 
Hyolithes cf. striatus .........c0c000++- Raheen Shales .| Newtown Head.) 762 
BRACHIOPODA. 
DIGS CEGENIED, .0secconctugedsaconccss Ordovician ...... Newtown Head.| 760 
COrthtsingd ©) CRISP cece senines 760 
Orthisina ef. sqyuamata ..........2.+-. Tramore Lime- \ WVALGHaT ooase. 760 
Porambonites intercedens var. stone Series . 
SESS SREP OR OE Fe EPS J 761 
LAMELLIBRANCHIATA, 
Anthracomya calcifera, sp. nov.| Upper Coal . 
Pl. xxv, figs. 14-20 o.cccesesese, Measures... .. PONS ons He 
Carbonicola Vinti. Pl. xxv, figs Upper Coal North Staffs & 
Sole Sgr AAS on ee 2 Measures...... Durhaur 2:2 36 
Ctenodonta pentonensis, sp. noy.| Hurlet Lime- } . 
Boley, HG Ss: Le eee. res an BELONG. ccs..0s «i Bentourhives -:| See 
GASTEROPODA. 
Ectomaria (?) exigua, sp. nov. PI. 
Ragtenst ONO) 5 oun ca cases uigen dts ciseus. . . rm 
Be anensis op uby.' Pl. xxi, Llandeilo ...... Ayrshire ...62..0- 256 
HEED Meme asain dansite cnucn=s deena 256 
pagoda var. orientalis nov.) \ (A 
Bee wed, fies, OO 4.5. sence). | 1 255 
os var. Peachii nov. Pl.) | Durness Lime- 
ee ee re es nee Mela ale } eg Oi 
Hormotoma antigua, sp. nov. PIl.| | 
7 SG SITES MA wae Se ea ne eles ) | 270 
articulata. Pl. xxii, figs. 7 Ledbury & 
ea a a | Ludlow Se \ Dudley ......| 268 
ie EE es Ges. ld } Upper Silurian .| Various ......... 264 
—— G 2 dubia, sp. nov. Pl. xxi, : , 
Bem ee Dupes 1AM0-!) Sutherland ..,... 263 
— (! * gracillima. Piece He Le wie een 263 
—— Grayiana, sp. nov. Pl. xxii,}| Middle Llan-| Woodland 
fig, 10 ............0022-seeeesereeeeee a: } GOVERY 0 s0c<500 PONE actriz 270 
eed nae Lae Wenlock Beds .| Ireland ......... 267 
— (1) Piperi, sp. nov. PI. xxii,} | Aymestry Lime- J oar 
HES WOO xe Set cle omic se nearctinte sees BLOG. oo pana OT ho -| 267 
Salieri, Pl. xxi, figs. 7-11...) Silurian ......... Warioug: 3.25.2: 263 
- Tea aoe ae \ Lower Dla) Dudley, ok 268 
GANOIDEI. 
Amia anglica, sp.nov. PI. i, figs. [ 
aa Mines aeiaeeameraehe aden. ease « Bembridge & . 3,5 
—— Colenutti, sp. nov. PI. i, Osborne Beds. Isle of Wight ... 


VEE AEA? ASS REO eRe oe a J | ls 


xii FOSSILS DESCRIBED AND FIGURED. 


Name of Species. | Formation. | Locality. Page 
MuGALOSAURIA. 

ee bt BE \ Penarth Beds | Bridgend.....-5.2. | 89 

CARINATS. 

(?) SHIGE.” (oetessstsaereent ane .| Wealden Beds .| Cuckfield......... 416 

PAISEEASDE | Vaviw ds encene+s + 46 dioeseaeee ] 419 

UOICODENCGTINUS io. .cvrtence-mssenscisine Saree 420 

TAUEUNEOTUSUICH © cscuraocvesacessa sacs i eee TRB ATO i 420 

Spatula clypeata .......05 aad weet j 420 
ARTIODACTYLA. 

oo LON BOE EE \ Weald Olay (?).| Tonbridge ...... | 413 

RopeEnTIA. 

TECGUS CUNICULUS a sriarees covemnoss oes ( 422 

—— Variabilis ......ccc0ee ee eee: 421 

WVITEROLUS GPOAUIS. 1. ecb eennnasesteaes: 425 

TUUOANIS( O) ies sah Sarctechiass otainiae \- Pleistocene .. ... Ightham .csseeees { 425 

EIIQUSPISCIUUSE «cern mistcchigcyadieieg wes siheler | 424 

Spermophilus erythrogenoides. PA. | 
RAV, HPS: FOE 2 ciscte vesme ns i) \ 422 
CARNIVORA. 

Gants TUS (OD) ine. sacaoew stake cinaee \ (427 

PECLISNCGUIS  oja hn telnet eB einaio el awe cisllate' | | 428 

WTE OULGOTIS (2) cite cencescescvewsss sa | 428 

DMICVES EOBUS. | laacranicte vsticelesieie bot see ais Le } Pleistocene ew eT es 428 

MUSCLE DUCOTIUS —. chise--iomicone eee see | | 425 

—— robusta. Pl. xxviii, figs. 1-6 .| ) | 425 
CHEIROPTERA. 

Vespertilio Bechsteini (2) .......0.+6- : | 420 

Daewoo iste \ Pleistocene ...... Ightham ......... 420 


EXPLANATION OF THE PLATES. 


PLAte Pace 


yr { Auta from the Oligocene of the Isle of Wight, to illustrate 
; Mr. KH. T. Newton’s paper on Remains of that Genus 


( GeoLocicaL SKETCH-MAP OF THE ParisH oF Tamwortu (New 
Sournh Watzs) ; Hortzonrau Sections NEAR TAMWORTH; 
Mippte (?) Devonran Rapronaxtan CLAYSTONEs ; Lamt- 
NATED AND CONTORTED RADIOLARIAN CHERT IN SUBMARINE 
Acinic Turr; and RapIoLaRIAN CuERTS, WITH SUBMARINE 
TUFFS CRUSHED INTO TEM, to illustrate Prof. T’. W. 
Edgeworth David & Mr. E. F. Pittman’s paper on the 
Palzxozoic Radiolarian es of New South Wales 


IIi-VII. 


Watss, to illustrate Dr. G. J. Hinde’s paper on those fossils 


ANCLODON CAMBRENSIS, sp. nov., to illustrate Mr. E. T. 


Newton’s paper on that fossil 


| 
&. 
c- S 
VITI-IX. Bones FROM THE DeryontAn Rocks or New Sovuru 
x. { 


Pee were eer se cereessestesesetseees 


( Map or tHe Upper anD Mippis PrerMian or THE SOUTH-EAST 
Suropssire Recrion; and Map or tne Permian ARBAS IN 
THE LOweR SEVERN Basin, to illustrate Mr. W. Wickham 
King’s paper on the Permian Conglomerates of the Lower 
Severn Basin 


KAT 4 


Peete meee eae ease eee e sees estes eseeesesssseeseesreseneses 


| 
| 
\ 
( Gxotocicat Map or Tae SovTHern Part or THE MaAtverns ; 
| RaceEepstone Hitt From THe Sours; and Vinw or Mip- 
XITI-XV.{ summer Hitt From THE RAGGEDSTONE, LOOKING NoRTH, to 
| illustrate Prof. T. T. Groom’s paper on the Geological 
| Structure of the Southern Malverns, eic. .................04 
VI RapioLariA FRomM Mutiion Parisi (Cornwatt), to illus- 
= { trate Dr. G. J. Hinde’s paper on those fossils ............ 


( nreere Section tHroucs Tissinaten, Higuway CLoss 
| Barn, and Crake Low Currines; and Vertican Sections 
XVIT-! or tue Beps agove tHe THICK Asn, BETWEEN TISSINGTON 
XVI. ] AND OraAkeE Low. to illustrate Mr. H. H. Arnold-Bemrose’s 
| paper on the Geology of the Ashbourne & Buxton Rail- 
Ki WEY, wavaxsiessnnnrsngy eaves Sips shave se pay gate saw aaine ove vieias of cea 


16 


38 


89 


224 


X1V 


PLATE 


XIX-XX. 


XXI- 
XXII. 


XXIII. 
° XXIV. 
XXy. 


XXVI- 
XXVII. 


XXVIII. 


XXIX- 
XXX. 


XXXI- 
XXXIV. 


XXXV- 
XXXIX. 


XL. 


| 
1 
| 
\ 


| 
| 
| 
| 


( 
| 
| 
( 


| 


EXPLANATION OF THE PLATES. 


PAGE 
(GxroroercaAL Mar or Tipesweti DALE AND THE NEIGHBOURING 


Area; and Inrrustve Doterits, Lavas, anp TurF From 
THE SAME Locauity, to illustrate Mr. H. H. Arnold- 
Bemrose’s paper on a Sill and Faulted Inlier in Tideswell 
DRO nekcecnasensacetsesendoainda nema sinomneicneneeh pins ts titer eee 


Ecromari14 AND Hormoroua, to illustrate Miss Jane Donald’s 


paper on those penera, 5. ..0..sens.neneeven ae husks ones bs ae 


VARIOLITIC SERPENTINES, ETC. FROM ANGLESEY, to illustrate 


Prof. Tl’. G. Bonney & Miss C. A. Raisin’s paper on those 
MOCKS 20s deen dassbcormaadene tae Je sublalnale teint <auieee cs aaksi naa amen 


KNOLLS NEAR SCALEBER, SETTLE, to illustrate Mr. J. E. Marr's 


paper on Limestone-knclls in the Craven District of York- 
BIAS VOLO: Gers cae sidan saceeldie dine to minciee so ees oun a re are eee 


ANTHRACOMYA, CARBONICOLA, AND CTENODONTA, to illustrate 


Dr. Wheelton Hind’s paper on new species of those 
FENETA. sere nsienes v1 side sion otal bttat Sheds xk ROLE AINONERIEA CRORE 


GroLocicaL SKETCH-MAP OF THE Davos District; and Sxc- 


TION OF THE MOoUNTAIN-FOLDS THERE, to illustrate Mr, A. 
Vaughan Jennings’s paper on the geology of that area 


MusTEtA AND SPERMOPHILUVS FROM IGHTHAM, to illustrate 


Mr. E. T. Newton’s paper on the vertebrata from the rock- 
fissure at that locality ............ MeFi veers Soboustenbuts sd Be aa 


GRANITE FROM SorEL Pornt, AND Orpnttic DIABASE FROM LA 


PriatnE; and Moprriep Di1aBasz FRoM LE Fossk Vice, AND 
THE SAME MORE ALTERED AT THE JUNCTION WITH GRANITE 
From La Hovtse, to illustrate Mr. J. Parkinson’s paper 
on an Intrusion of Granite into Diabase at Sorel Point ... 


GEOLOGICAL SKETCH-MAP OF THE HAvRAKI GOLDFIELDS; 


Ruyouirses or Mercury Bay anp OmMAnu ; Ruyo.iTEs, ETC. 
oF THE HaAuRAKI GOLDFIELDS; and Ruyo.iTes or Omauu, 
Waint, anD Watxino (N.Z.), to illustrate Messrs. J. Park 
& F. Ruiley’s paper on the Rhyolites of the Hauraki 
Goldfields ...... Hainttho crea oleate ectdlts bo oia MB tbvaletb hols sie wine AMD 


DEMONSTRATION OF THE PERSISTENCE OF PROFILE-SHAPES 1N 


MicrAstErR; ANTERIOR PAIRED AMBULACRA OF MzcRASTER; 
SINGLE AMBULACRA AND BaSsEs OF THE SAME; Bases, PrERI- 
STOMES, AND PLASTRONAL TUBERCLES OF THE SAME; SUB-ANAL 
FascioLEs, ETC. OF THE SAME, to illustrate Dr. A. W. 
Rowe’s paper on that genus ............... a taseeWalivetwas sien 


GrvERAL GROLOGICAL MAP oF THE SELLA MASSIVE AND ENNE- 


BuRG, to illustrate Miss M. M. Ogilvie’s [Mrs. Gordon’s]| 


239 


276 


327 


.. OOl 


419 


430 


449 


paper on the Torsion-structure of the Dolomites...... sreves OUR 


EXPLANATION OF THE PLATES. 


XV 


PLATE PAGE 


(Mar or Cxnrrat SpitsBercen; VIEW OF THE GUACIER- 

systEeMS IN Kine@’s Bay; THE TerMinaAL Front or Kineo’s 

GuactER ; IcEBERGS CALVED FRoM Kin@’s GLACIER; A 

COLLAPSED ICE-TUNNEL, NEAR PRETENDER PEAK; IcE- 

| TUNNELS FORMED AGAINST THE PRETENDER RANGE, AND VIEW 

XL or NUNATAK CAUSING ELEVATION OF ENGLACIAL MareErtat ; 
XLVIII.% SuRFACE-STREAM ON HicgHway GLACIER, AND ENGLACIAL 
Stream with Morarng, Kine’s GLAcIER; THE RANGE oF 
THE Hornsunps TinpDE, FROM Mount HeEpGenHoG, SHOWING 
FROsT-DENUDATION, AND ONE OF THE ERRATICS OF TIE 
ArcH#AN Moraine, NorDENSKJOLD GuactER, to illustrate 
Mr. HE. J. Garwood’s paper on Glacial Phenomena in 
OPMUSDEM BEM ie eiacsavemewacsnav cone ce sineeploeeeatan 


—o 


eeeeeessese00e 


ORDOVICIAN TRILOBITES FROM THE WATERFORD COAST, to 
XLIX, illustrate Mr. F. R. Cowper Reed’s paper on the Lower 
Palzozoic Bedded Rocks of that district .........cscs.seeeee 


(Tutckness oF THE Upper AnD Mippie PERMIAN IN THE 

Dents | Envirnze Disrricr; and Comrosition oF THE PEBBLES 
Ié Il { «N THE Mippie Peruran Conetomerates, to illustrate 
" | Mr. W. Wickham King’s paper on the Permian eee 

\ merates of the Lower Severn Basin ...cec...cccceesescccsssees 


681 


718 


97 


PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES, 


Fig. 


1-5.{ 


ie 


2. 


4-6. 


es 


BESIDES THOSE IN THE PLATES. 


Diagrammatic section néar Melmerby: wi.j:0.csas0-ou-a<ne eee ee 13 


Section in quarry at Tamworth Common (N.S.W.) pees 
the intermixture of radiolarian cherts and submarine tuffs... 22 


Plagoniscus cristatus, sp. nov., Pl. colligatus, sp. nov., Pl. (2) 
DELUSTUS, Sp. MOVE, ANG, PLAC O)aSp.. . oc dacaainaenteacen@tt nee eee 57 


Continuous section along the Great Central Railway, from 
Aue by tO" Caces by 42 .éc et vaneenedneaes megepapeees 66, 70, 72, 74, 76 


Restored section of the Enville District along the strike . 106-107 


Diagrammatic plan of the structure of the north-western corner 
of Raggedstone Hill, and of the south-western part of Mid- 
eummmaer Ha 5s nts'sfaanriinn atom tetenehe oad aan awaeet ee 132 


( Sketch-map of the eae of the large quarry at White- 


leavem Oak: \ ciicivccédeudeencee se teacecentmecee teehee 134 


Section at a point south-south-east of the large quarry at White- 
leaved alk 0. seis ccs See nasactqeeseinaicleare maples sve eee ee eee 135 


Sections across the south-western part of Raggedstone Hill ... 136 


Section of the northern part of the large quarry at White- 
leaved Oak |. ccisensedsabeiediuen nits aek cade cdbecesasheran anette eee 136 
Section across the northern slope of Midsummer Hill ......... 140 
Section of dyke on the northern side of Hollybush Pass ...... 140 
Section across Midsummer and Hollybush Hills ............... 141 
Diagrammatic section in the Hollybush Pass ..................... 143 
Section immediately north of the road in the Hollybush Pass. 144 
Section across the southern part of Raggedstone Hill............ 144 
Section in Winter Combe (north side of Raggedstone Hill) ... 146 
Section across the northern part of Raggedstone Hill ......... 147 
Section! across Chase Hind Hill) 5 o:cucsseseteecpeae nese once 149 


PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES. XVil 


Fig. PacE 
18 Theoretical reconstruction of the section across Raggedstone 

Pa SETI larterien Ne ae assed sein eaweidacssceeaestonc. sasetsedtansscavceac oes 152 
19. Diagrammatic view of the structure of Midsummer Hill ...... 154 


20 Theoretical restoration of the section of the Malvern Hills 
; alone the lime of the Malvern Tunnel’ ..... 2.06600. 0-s0cecseess 156 


21 { Section of Cambrian and Silurian rocks, between White-leaved 


Os qands Howler Marm  f inc. nscaeemeua masses sate detec acieccaas ea 160 
Geological Sketch-map of the neighbourhood of Conway ...... 172 
Diagrammatic section of the rhyolite-series at Bodlondeb ...... 174 

iy Maprot the Naparima: District ~ ..5..2-22 ssh ardee aseeosneseeeesnecs 182 
2. Comparison of the rock-succession in Trinidad and Barbados. 186 
eee ceae section from the plain of Demnat to the central 

CEESH Ol ENO LATIASE «cis adacs cocensendomehacdgeonesoheasesneeebuache gee 200 

9 { Diagrammatic section from Tezert, across the main axis, to 

Teluet and the plateau of the Anti-Atlas .....................08. 200 


3. Diagrammatic section from Achliz Urika to the Jebel Asif Sig. 204 


4 f Diagrammatic section, following the Wad Reraya, from Tagh- 
ple pongighon Uizik Balm We doth. get oe dt oincadecd ies tad ban vache sine 204 


Diagrammatic section from Amsmiz, across Jebel Tezah, the 
slonyot Gindaty, amd: WiShdana. 3 5vsn.00ses0c<0vensmes otansaeine snicas 208 


6 Diagrammatic section from the plain of Morocco across Marossa, 
; Wirzan, and Jebel Ogdimt to the valley of Sus ............... 208 


cutting, and across the northern and southern ends of High- 


Diagrammatic sections across the northern end of Crake Low 
1-3 
wabynC Ose baALMVvCULtIMe —.)ehdes.cvotercccedeceotascvcssotceeeuat e+e 230 
i. 2 Seetion, across. Lideswelll “Dale sai a.c5c ness las ac lens ee wosekw os 244 


) Diagrammatic section along the middle road from Miller's 
Dale -towiceswell 752k. ci etaccwn asses aiteedtnceneoecumewevdiessauiiec 244 


Sandstone containing fragments of granite, Aghnagreggan 


(Coumipy My Rone \p ccc acccs ane dadtensi nections vas ateccindcoaradace 
1-2. Variolitic serpentine from near Rhyd-bont and Pwll-pillo ... 282 
1. Section at Forchhammers Pynt (Moen)..................ceececeeeees 308 
2. Section in cliffs near Sandskredsfald (Moen) ................. .+. 309 
3 lee in pit west of Krampass-Sassnitz railway-station 
(CED 72) 60 Roe renee Reree aan ee tec Bh SRA SORIA wcieciBe i disd aeullatsel 315 
4-5. Sections at the Kielerbach (Riigen) ................ceceeeecees 316, 317 
6-7. {patel south of the Kollickerbach (Rigen) [2méscalled Wald- 
|e, as Meats MAME mere Secale ee ttn Mn ee 318 
8. Section under the Blockhouse (Riigen) ..................cecccee eee 320 
1. General view of the eastern end of Draughton Quarry ......... 332 
2. Cracked fragments in breccia, Draughton Quarry ............... 333 
VOL. LY. b 


XViil PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES. 


Fig. | Pacs 
3. Chert-band in limestone below middle shale, Sea 
(MMOS cies cace = ssc Sewio om ase eae sued ssscneheceni ae tee Met maa em Ee 335 
Folded limestone in middle shale, arch of left fold, Draughton 
4-5. 
LEI eee n suis esinsa.ca.cwe ae cae's «4/4 080 nose onc ee Ree eee ete eee 336 
G Folded (?), faulted, and brecciated limestone-band, Winterburn 
: FRESELVOIT Voie. oe. e0c menace saiiece ts seg ee eee ee eee en eee 340 
7. Pseudostromatism (?) in limestone, Otterburn Valley ......... 341 
8. [Artificial production of. knoll-structure] .............cesecesesesees 342 
9. Limestone-breccia, Draughton Quarry ..:.......<.<e.0ca00+se-ss0see 344 


10-11 Broken and folded limestone, aa brecciated fragments, Otter- 
F burn: Valley: 2 aude tence eeecer tear ton cacs-concls eat 345 


12 ‘inde limestone in shale, forming breccia, east of Scaleber 


once; Settle: nn iaias ich heoke eee Me ee 346 
13. Specimen of ‘pebbly ’ Winterburn breccia .............-:ssseseone 348 
1, { Sketch-sections illustrating the distribution of the rocks in the 
Daivos Distrieiy 2 yi..:otsts or eten nc doce nacetenee seas -on teh ae eee 388 
Specimen/of “polyeenic Wreccia \2.,./s.--).-2-+-16eeese ee eee 396 
The Strela Fold : exposures on the east side of the lake......... 402 
4. The Cotschna Fold: section on railway by Laret Station ...... 402 
5-6 Strela and Cotschna Folds: outcrops on the east side of the 
: Lareterbach and on the Eastern Rhatikon ..................... 404 
7 The Cotschna-Arosa Fold: rock-exposure east of the Parsenn- 

; Burkes ore 02.205. hte eeemrecten Ls SUR OEE toe 407 
Hemiomus major, gen. et sp. nov.: distal end of humerus ...... 414 
Left femur of bird (?), distalend ia, c.sceent sce ae-e-te ee eee eee 417 

1 Part of an orthoclase-crystal derived from granite, embedded 
in material mostly derived from diabase ...............eceeeeeee 436 


2. Corroded plagioclase lying in an uniform felspathic substance. 436 


Sketch-map of the district of Loch Awe ............:eeceeceeeeeees 472 

1. Sketch-map of a portion of Congleton Edge ..................:..00+ 548 

2. Section along C D (in the foregoing map) ...........:ssseeeeeseeeees 550 

a.) Do, along hE do do. ) avis ncinewaeenieamm sen eee ee 552 
4. Do. along AB( do. do. Dy sWhionit sietichee tera ace aoemomte 553 

5. Do. along GH( do. do. ) teach tenle sens aN ic eee 555 
1,4. Sections through the anticlinal buckle of the Groden Pass. 568, 572 


9-3 Fold-form, and nomenclature of the same, west side of the 
Groden Passantieline: 5.5.6 l2.ci see ee tea e eee selects sie eee 568 


5-6 Fold-form, and nomenclature of the same, east side of the 
Groden’ Pass antielime: 6606 scs0ilccisdc kw ree ee een eee 572 


PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES. x1x 
Fie. PAGE 
‘au, Lorsion-system of the Groden: Paes: ic... seseocccancasecrcacass ce 578 
8. Diagram illustrating the torsion-movements at the Groden Pass. 581 


9 cee ea in the southern face of Cherz Hill, towards 


VIERA periene cea atta eae err inte ssietanaadign Saehtueabumde seme saison 584 

10 { Parallel sections from Monte Sief and Cherz Hill to the’ 
; Pie Mensbetney VACY 120.1 denen te seeccenncden vee nnscnueiheatee Se semwes 586 
1]. Faults in the fold-form of the Buchenstein Valley ............... 586 
12. Fold-form of the Buchenstein Valley and Sett Sass_............ 586 
13. Scheme of torsion-faults in the Buchenstein Valley ........... 588 
14,16. ‘Transverse sections through the Sella Massive ............ 592, 594 
15.17 Wold-torms of the SellagMassive: » -..iis.c.-s-esaeetadass noes 592, 594 
ig: Infold-of Jurassic rocks (Boe summiib) 21.0... .cce.cccsseeedencve <== 606 
19. Diagram of torsion at the Boe summit .................ceeseeneeeees 607 
20: The Sella folds, before and after forxsiow .-..2.0.--.6c.eces.anceeres 609 
21. Contour sketch-map of the Enneberg district ...................4. 614 
99 | cea ee strike-torsion in the peri-Adriatic area of ae 
i Basternrside of Porthoyr HbOR i... ccosesccconssspacsseevesemaenemetl> 645 
2. Sketch-map of the north-western corner of Anglesey ............ 646 
3. Section at Ogof Gynfor, near Llanbadrig ....................+. Ea: 648 


4 Contorted green phyllites: part of rock-face in quarry behind 
Rectory, Miantair-y/menOngwy i c.es nd. cbmc csueeanarcionease 651 


5. Section in quartz-knob, Llanbadrig Point .....................00. 653 


6 Porth Newydd: small horizontal faults in the cliff north of 
therOxdovician boutdarye, )sccce.iee- ce serene seek nae deous as sokwee 654 


7 Disrupted grit-courses in Ordovician black shales, Porth 
HNIe ay GLO bene Nira sas fata tee cee eS OVS nt Miter cloutcs 656 


8. Section north-west of the pier, Cemaes ...............scsceceeeeeeees 658 


9 Section through the crush-conglomerate on the coast, Penrhyn, 
‘ OMAR ris iaee hc den oo waiser ae snernens Sales dnpiscaeiniduiosnweaindew tdomeane 660 


10 Rock-face on Penrhyn, near Cemaes, showing relics of strati- 
fication in the crush-conglomerate ..........cc0ssccesesscsecsecesee 662 


11 South-eastern corner of Cemaes Bay: parts of broken quartzite- 
; AIG Set eck use ewar ceo dell saute wanes shasatacciaania caer s due sab meenuisee ser 664 
12. Quarry on the east side of Craig Wen, looking north ......... 671 


13 Purple band in cleaved grits and conglomerates, on the coast 
lg westvon eoctin VilaiMienity .c. nasety jon dcnatecatemesnes «t's veup es toslnes 673 


Eucladia Woodwardi, sp. nov.—Reconstruction, dorsal and 
1-2 
WOHLE A ASPECS ween. setces cea sugad-aetiesse podas belies eaincay bicawatveuse 694 


xX PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES. 


Fie. Paar 
3-4, Euthemon igerna, gen. et sp. nov., ventral aspect ..........0.se.000 698 
Ambulacral and adjacent interambulacral plates of Myriastiches 
GV GS, BON. CLS. MOV. S.lesnessenseessehseageeesaseeacreaeeneeeeeeee 701 
6-7 Palgodiscus ferox : ventral aspect of the peristomal region, and 
lantern of Aristotle seen from within — .............scsssseseeees 702 
8. An isolated tooth of Palcodiscus ferox 00.5.) cc.cccs00.cuee eee 703 
9=11.. Ambulaccum of Palcodiscws ferom -..vc.ch<ssssasesecnseses tee 704 
12-13. Part of an ambulacrum of Hehinocystis pomum  .......c.cese0eeee 708 


Transverse sections through the ambulacrum of a specimen of 
Echinocystis pomum partly preserved in carbonate of lime... 709 


15-16. { Goniocidaris canaliculata: inside view of the peristomal plates 
and side view of the buccal armature .................ssessseseeees 712 
1, { Diagrammatic section of the foreshore on the north side of 
; Newtown Elead’ io. scesacssrsosce soe cnsaceeienetit ee 722 
2. Ground-plan of disturbed beds on the foreshore near Tramore. 725 
3. Section in the cliff-face between Tramore and Doueraile Cove . 726 
‘4, Ground-plan of the foreshore near Tramore  ............esseese0s 127 
5. Section in the cove below Doneraile Walk ..............1eseeeee- 728 
6. Section in the cliff below Doneraile Walk  ............0..see0s-00e 728 
7. Section in the cliff, 40 yards north of Doneraile Cove ......... 729 
8. Section in cliffs of northern cove opposite Carrigaghalia ...... 730 
9. { Section at the base of the cliffs, near the western end of 
Garrarus Strand. s.ccesc.casdse0s ceecemeniees see caean ae eee 733 
10-12. Cliff-sections, Kilfarrasy Strand .....0:.- sss. <e.-<eecenee seer 734, 735 


13 ( Section of sigmoidal fold in the rocks on Morageeha Strand, 
AmnestOWi. cescc. Ueda ties vets tease cee ee 736 


14. Section on the west side of Dunabrattin Head ..................... 736 


15 f Section at the base of the cliff below the engine-house, Knock- 
; TUUEIIOTD se nies.ncoin said sate epee Mie cbato ab con Ree oe eve 738 


ERRATA. 


P. 318, figs.6 &7. [Owing toa mistake which I made in selecting the drawings 
for reproduction, a pair (Figs. 6 & 7) representing a section south of 
the Koniickerzsacn have been used to illustrate corresponding views 
under the Waldhalle. The association of Chalk and Drift is nearly 
the same in both, but the true Waldhalle sections do not show the 
Boulder Clay coming in again on the edge of the Chalk-cliff as it 
descends to the beach.—T. G. B., July 17th, 1899.] 

P. 473, line 4 from top, for ‘approch,’ read ‘ approach.’ 

P. 481, line 17 from top, for ‘Lag-na-Linnge,’ read ‘ Lag-na-Luinge.’ 


Vol.LV. FEBRUARY ist, 1899. No. 217. 
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Vos GY: 


1. On the Rematns of Anta from Outeocene Srrata in the Istu 
of Wient. By E. T. Newron, Esq., F.R.S., F.G.S. (Read 
November 23rd, 1898.) 


[Puartz I.] 


TreE remains of fishes closely related to the living Ama calva were 
recorded by Prof. O.C. Marsh’ in the year 1871 from Tertiary 
strata in Wyoming (U.S.A.). These remains were thought to belong 
to two species, both about the size of their living representative. 

in 1873 Leidy? described and figured several vertebre from 
the Bridger Beds of Wyoming which seemed to him to be allied to, 
but generically distinct from, Amia calva; for these he proposed 
the two generic names of Protamia and Hypamia, the former 
including three species and the latter one. 

In the same year Cope* described from the same locality, but 
without figures, a number of vertebre with associated jaws and 
eranial bones; these he referred to five species, and included them 
in one genus, which he named Pappichthys. Two species of Amia 
were described by the same author * from Hocene shales of Florissant, 
Southern Colorado, and two’ from Miocene beds, Cypress Hills, N.W. 
Territory (Canada). Subsequently Cope* redescribed and figured 


1 Proc. Acad. Nat. Sci. Philad. 1871, p. 105. 

2 Rep. U.S. Geol. Surv. Terr. 4to, vol. i, p. 184. 

8 6th Annual Rep. U.S. Geol. Surv. Terr. 1872 (pub. 1873), 8vo, p. 634. 
4 Bull. U.S. Geol. Surv. Terr. 1871, p. 1. 

° Contrib. Canad. Palzont. (Geol. Surv. Canada) vol. iii (1891) p. 2. 

6 Rep. U.S. Geol. Surv. Terr. vol. iii (1884), 4to, p. 56, pls. ii-iv. 


Siete io. No. 217. B 


2 MR. E. ‘I. NEWTON ON REMAINS OF [Feb. 1899, 


his species of Pappichthys, discarding Leidy’s names on the ground 
that no diagnosis had been given, and retaining his own name of 
Pappichthys, concerning which he says’ :—‘ This genus differs from 
the existing Amia in the presence of only one series of teeth instead 
of several, on the bones about the mouth. The vertebral centra 
possess a smaller antero-posterior diameter, and relatively greater 
transverse diameter, in the anterior part of the column; but the 
value of these characters is not yet certainly understood.’ In so 
far as the dentition is concerned, this diagnosis would include Amia 
also, for a single row of teeth on the maxillary, premaxillary, and 
dentary bones is characteristic of both the fossil and living forms; 
the extra rows of teeth on the inner side of the lower jaw of Ama 
are not developed on the dentary element, but on supplementary 
splenial bones. We now have evidence (PI. I, fig. 17 *) that similar 
supplementary teeth-bearing bones existed in the fossil forms 
described in the present paper. Cope calls attention to the fact 
that the palatine bone of his P. plicatus ‘ exhibits a series of large 
marginal teeth and numerous smaller ones within them, as in Amia 
calva.’ * 

The diagnosis of Pappichthys, therefore, is restricted to the 
characters of the vertebrae, and these are practically what were 
given by Leidy, whose name of Protamia must be used for these 
fossil forms, if they are to be generically separated from the living 
Amia, but it is by no means clear that they should be so separated. 

Prof. A. Andreae* has described some very similar fish-remains 
from the Lower Miocene of Messel, Darmstadt, which he names 
Amia Kehreri, preferring to assign the fish to this genus rather than 
to adopt either of those proposed by Leidy and Cope, evidently 
having doubts as to the difference of dentition, which Cope thought 
existed, a supposition which led him to separate his fossil fishes from 
the living Ama. 

Mr. A. Smith Woodward * gives full references to all the known 
fossil forms which are nearly allied to Amza, and includes in this 
genus some isolated vertebre from the Upper Eocene of Hordwell, 
Hampshire, which agree very closely with the American specimens, 
and also with those now to be described. 

Some years ago my colleague, Mr. Clement Reid, obtained the frag- 
mentary remains of a fish from the Bembridge Marls at Hamstead, 
Isle of Wight, among which were vertebre and other bones closely 
resembling some of those referred to above from the Tertiary strata 
of North America. In the hope that better material would be found, 
these bones were allowed to remain unrecorded. More recently 
Mr. G. W. Colenutt has found many portions of similar fishes not 
only in Bembridge Beds, but also in the Osborne Series of King’s 
Quay, near Ryde, and has very courteously placed them in my hands 


1 Rep. U.S. Geol. Sury. Terr. vol. iii (1884) 4to, p. 56. 

2 Ibid. p. 59. 

3 Abh. Senckenb. naturf. Gesellsch. vol. xviii (1894) p. 359. 
4 Brit. Mus. Catal. Foss. Fishes, pt. iii (1895) p. 367. 


Vol. 55.] AMIA FROM THE ISLE OF WIGHT. 3 


for description, as they materially assist in the elucidation of the 
structure of these interesting fishes. 

That these British remains are closely related to the Amza-like 
forms recorded by Marsh, Leidy, Cope, and Andreae cannot be 
doubted, for the proportionately short and wide vertebre of the 
anterior abdominal region, with their long transverse processes and 
double scars for the attachment of the neural arches, as well as the 
perforation for the notochord, are practically identical with those 
of the American and European forms; moreover, most of these 
peculiarities are likewise to be found in the vertebrae of Anwa calva. 

Whatever may be done eventually with the Transatlantic species, 
I am disposed to refer the British forms to the genus Ama, and in 
so doing shall be in agreement with Prof. Andreae and Mr. Smith 


Woodward. 


AMIA ANGLICA, sp. NOY. 
Specimen I. (PI. I, figs. 1-5.) 


The bones found by Mr. Clement Reid in the Bembridge Beds of 
Hamstead, Isle of Wight, lay all so close together that there is 
every reason for believing them to be parts of one fish; they include 
four vertebre, a maxilla with its supplementary bone, portions of a 
dentary bone, of a parasphenoid, of a clavicle, and of other bones. ~ 

Vertebre.—tThe four vertebre are from the anterior part of the 
column, the prominent transverse processes being high upon the sides 
of the centra; all these vertebree are proportionately short and 
broad; they are deeply biconcave, and pierced a little above the 
centre by a small notochordal aperture; their greatest width is 
opposite this perforation, and they narrow rapidly below, so that 
the terminal face is somewhat pointed inferiorly. It is uncertain 
whether these vertebre form a consecutive series, but when they 
are so arranged that the vertebre with the highest lateral processes 
are in front, then the anterior centrum is the shortest and widest, 
while the hinder centrum is the longest and narrowest. The third 
vertebra of the series is the only one that has a perfect transverse 
process, and this is 9 mm. long, with an expanded distal extremity. 
Each centrum has the upper surface marked by four depressions, 
indicating that each neural spine was attached to two vertebra. 
The lower surface shows a pair of longitudinal spaces which seem to 


have borne bony processes. (PI. I, figs. 1-2 a.) 


Measurements of Vertebre in Millimetres. 


I EL TIT IV 

Tienigth °..75.2.d-.0-2 9 10 10°5 11 
Prteniib 2.2225 tack. 23 22 22 22 
VG ane eae eee 29 29 28 27 


Maxilla.—The most perfect bone of the head that is preserved 


is a left maxilla (Pl. I, figs. 3 & 3a); but the teeth are wanting, 
B2 


4 _ MR. E. T. NEWTON ON REMAINS OF [Feb. 1899, 


and part of the hinder end is broken away. The length of this 
bone, measured round the outer curve, is 130 mm., and it may have 
been 140 mm. when perfect; its greatest depth, 28 mm., is at the 
hinderend. The anterior part shows the smooth surface overlapped 
by the premaxilla, and then a depression of the upper margin, which 
probably received the lachrymal bone. Farther back the upper 
margin has two prominences: the posterior prominence marks the 
position of the front of the supplementary maxilla, and behind it 
is a pit and groove for the reception of the last-named bone; the 
anterior process, if we may judge by the arrangement of the facial 
bones of Ama calva, marks the division between the lachrymal 
bone and the first of the suborbital series, but there is nothing in 
Amia calva, nor in any of the maxille figured by Cope, corresponding 
with this anterior process; the posterior process, however, has its 
counterpart in both those forms. 

The outer surface of the maxilla becomes somewhat rugose below 
the anterior process, and these rugosities become longitudinal streaks 
towards the thin hinder part of the bone. The oral margin is 
slightly concave, and shows the bases of a single row of 45 or more 
teeth ; these are large in front (4 in 19 mm.) and smaller at the 
back (15 or 16 in the same length), where they become crowded 
together and tend to form tworows. ‘he supplementary maxilla is 
represented by about 35 mm. of its anterior part, which fits into the 
shallow groove on the upper border of the maxilla ; its outer surface 
is rugose above, and longitudinally streaked below (PI. I, fig. 3 6). 

Mandible.—About 50 mm. of a left dentary bone is preserved 
(fig. 4), but both ends are imperfect; its greatest depth is 27 mm. 
The outer surface is streaked with sharp thin ridges above and, 
though somewhat less so, below ; while the median part is roughened 
by short, irregular, and oblique grooves, with projecting edges, which 
communicate with openings that penetrate the bone, very much the 
same asin Amia calva. The upper or dentary surface is 14 mm. 
wide in the middle, and a little less towards the front; its outer two 
thirds are occupied by the bases of a single row of seven large teeth, 
while the inner third forms a flattened margin. In Amia calva this 
inner margin supports a row of ossicles (supplementary splenials) 
which carry two or three rows of small teeth ; and a specimen from 
King’s Quay, in Mr. Colenutt’s collection, retains one such tooth- 
bearing ossicle still in position (Pl. I, fig. 17*): this shows that the 
dentition of the mandible in these fossil forms was essentially the 
same as in the living species. The hinder teeth of this dentary bone 
were the largest, three of their bases measuring 24mm. The inner 
margin of the dental surface turns abruptly downward to form the 
inner plate, below which is a large cavity, doubtless covered during 
life by a broad splenial bone; this cavity is continued anteriorly 
into a groove, such as Cope describes in the American forms. The 
lower margin is sharp and knife-like. Unfortunately this dentary 
bone is too imperfect to show its proper form, but Mr. Colenutt has 
several smaller specimens from both Bembridge and Osborne Beds, 
doubtless belonging to this species, which to some extent supply the 


Vol. 55.] - AMIA FROM THE ISLE OF WIGHT: D 


deficiency (see Pl. I, figs. 15-16). There is no proper symphysis, but 
the anterior extremity is a thin edge, which curves downward and 
backward from the dentary margin, and, continuing almost parallel 
with the latter for some little distance, somewhat suddenly descends, 
there being thus a rapid increase in the depth of the hinder half of 
the bone. The external rugosity continues to the anterior end, and 
in all the specimens there are a few of the rugose apertures near 
the curved extremity. ‘The groove on the inner surface is a broad 
flattened space that widens anteriorly (see Pl. I, fig. 15 a). 

The clavicle and preoperculum have rugose sculpturing on 
their outer surfaces. The parasphenoid (Pl. I, fig. 5) has a 
large flattened area on its oral aspect, covered with minute denticles ; 
and fragments of several thin bony plates, evidently from the oral 
cavity, are similarly armed. 


Specimen [I]. (Pl. I, figs. 6-14.) 


A second specimen, which includes several parts of one fish, and 
is to be referred to the present species, was obtained by Mr. Colenutt 
from Bed 5 of his section of the Osborne Series at King’s Quay * 
(isle of Wight).. These benes were all found near together, and 
there is but little doubt as to their pertaining to one fish; they 
include fifteen vertebre, a pair of premaxille, part of a dentary 
bone, several pieces with ornamented surfaces (evidently belonging 
to the skull and opercular apparatus), and a single scale which, 
though imperfect, is most valuable as further evidence of the 
affinities of these remains. This fish was somewhat smaller than 
specimen No. I above described, but, in so far as comparison can 
be made, agrees with it in all essential particulars. 

Vertebre.—All the vertebra are somewhat asymmetrical (Pl. I, 
figs. 6-10) ; seven belong to the anterior part of the column, and in 
form agree very closely with those of specimen No. I. Only the 
bases of the transverse processes are preserved, but these suffice 
to show the relative positions of the vertebre in the series. The 
centrum which bears the processes highest up on the sides has an 
almost quadrate terminal face, and must have been very near the 
skull. The third vertebra of this series agrees as closely as may be 
with the first vertebra in the previous specimen, but it is not quite 
so pointed below. 

The variations in the proportion of length, height, and width of 
these vertebre are shown by the following measurements of some of 
them :— 


Measurements of Vertebre in Millimetres. 


brie? Oyen 249) Ex XI Melek Ry 
Length ......... 8 9 10 95 85 5 
Height ......... 18 18 17 18 16 14 
Width ......... 25 24 21 185 15 14 


In No. XI the height and width are equal, and the processes 
1 Geol. Mag, 1888, p. 358. 


6 MR. E. T, NEWION ON REMAINS OF [Feb. 1899, 


are so low as to be almost under the centrum; it was evidently far 
back in the abdominal region. No. XII (PI. I, fig. 9) has the pro- 
cesses near together below the centrum and directed downward, 
showing that it belonged to the caudal region. The shortness of 
No. XIII (Pl. J, fig. 10), and the position of its neural and hemal 
articular surfaces, seem to show that it is half of a double caudal 
vertebra, and that it alone carried the neural and hemal arches. 

An isolated caudal vertebra in Mr. Colenutt’s collection (PI. I, 
fig. 18) is remarkable, not only for its proportionately great length, 
but also for having three pairs of articular areas on the upper 
surface, while there is only one elongated pair on the lower surface. 
In the caudal region of Amia calva it sometimes happens that two 
of the half-vertebre coalesce, but then there is only one neural and 
one hemal spine. It would be interesting, therefore, to know how 
the three pairs of surfaces could be utilized. 

Mandible.—The only portion of a lower jaw preserved is a 
fragment of a dentary bone, and this, so far as comparison is possible, 
corresponds with the Hamstead specimen, but is a little smaller. 
The bases of six teeth are seen, the hindermost being the largest, 
and three of these measure 21 mm. 

Premaxille.—A pair of almost perfect premaxille (PI. I, fig. 11) 
show the bases of six teeth on the left side and of seven on the right ; 
they are smaller than those of the mandible, three of the largest 
measuring only 14mm. Two of the anterior teeth are still in 
place; they are fixed to the jaw by inflated but compressed bases ; 
their apices, however, are round, sharply pointed, and incurved ; 
the length of each is about 10 mm., and the distal half is dark and 
shining. The outer surface of these premaxille is devoid of orna- 
mentation ; the suture between the two is still to be seen, but they 
seem to have been firmly attached to each other. The front part of 
these combined bones is convex, but above the third tooth, on each 
side, there is a deep depression with a foramen at jts upper part. 
Directly above the median suture there is a deep indenture of the 
upper margin. When viewed from below the two bones are seen 
to be so nearly in one line as to form but a slight curve, thus 
indicating a broad snout, which would agree with the form of the 
maxilla in the Hamstead specimen. 

Bones of the Skull.—Portions of several strongly ornamented 
bones are preserved which belong to the skull and gill-covers. One 
or two fragments are pieces of the preoperculum, and others with 
less rugose ornamentation are most likely parts of the clavicles. 
Two fragments of highly ornamented bones are figured (Pl. I, figs. 12 
& 13), but none are perfect enough to show their form. 

Scales.—A single very imperfect scale was recovered with this 
specimen (PI. I, fig. 14), but, although little more than an impression 
on the matrix, it is sufficient to show a very close resemblance to 
those of Ama calva. This scale is 18 mm. long, and 10 mm. wide at 
its broadest part, which is towards the hinder end; posteriorly it is 
obtusely pointed, anteriorly narrowed and truncated. Only a small 
part of the scale itself is left, but the impression of the outer surface 


Wol, 5a.) AMIA FROM THE ISLE OF WIGHT. vs 


left upon the clay shows this to have been ornamented with very 
fine lines (12 to 14 in a millimetre), which, radiating from near the 
posterior pointed end, curve gently outward and forward, running 
nearly parallel with the margins, but apparently terminating suc- 
cessively upon the margins. On close examination this ornamenta- 
tion is seen to consist of a series of grooves separated by sharp 
ridges. The under surface of the scale has a distinct smooth margin, 
within which it is granulated. 

Three very similar scales (Pl. I, figs. 19-21) were found by 
Mr. Colenutt in Bed 3 of the King’s Quay section, and probably 
belong to the present species. ‘They vary in size, and are not quite 
so pointed posteriorly as the scale above described; but the orna- 
mentation is the same, and the lines show a tendency to converge 
towards the anterior part. The scales of Amia Kehreri figured by 
Prof. Andreae* have a very similar form and structure. 


Besides the two specimens just described, each of which includes 
several parts of the fish, Mr. Colenutt has obtained numerous 
isolated bones, from the Bembridge Marls of Thorness Bay and of 
Hamstead, as well as from Beds 2, 3, & 5 of the Osborne Series 
of King’s Quay. Some of these jaws and scales have been figured 
and alluded to above, as supplying details which were wanting in 
the two more perfect examples. That the specimens vary much in 
size is evident from the figures of the dentary bones (PI. I, figs. 4, 
15, 16 & 17), and a similar variation occurs among the vertebre ; 
but otherwise there is so close a resemblance among them that in 
the present state of our knowledge they can only be referred to one 
species. , 


The vertebre of the specimens above described agree very well 
in size and form with those to which Leidy gave the name of 
Protamia media, and still better with those which Cope referred 
doubtfully to the same species; but the peculiarities of these 
vertebree are found in all these Amza-like forms, and seem to point 
to a close generic affinity, and not to specific identity. 

A satisfactory comparison of fragmentary bones is difficult; but, 
so far as it has been possible to make comparison, the English 
specimens do not seem to agree precisely with any of the American 
species. The forms of the maxille and dentary bones are different, 
and the external sculpturing is not alike. The same may be said 
with regard to the Amia Kehreri from Messel, for although there is 
a great similarity there is not identity of form. 

The proportionately greater width of the anterior vertebra, which 
has been held to be sufficient for a generic separation from Amia 
calva, will prevent these fossils from being referred to that living 
species. : 

"Tb is proposed to name this Isle of Wight ganoid Amia anglica, 
and it will be distinguished, in so far as its characters are at present 


1 Abh. Senckenb. naturf. Gesellsch. vol. xviii (1894) p. 359 & pl. i. 


8 MR. E, T. NEWION ON REMAINS OF [Feb. 1899, 


known, (1) by the form of the maxilla, which has two processes on 
the upper margin, and a deep curvature indicating a broad snout ; 
and (2) by the coarse sculpturing of the outer surface of many of 
the bones. 


Ama Cotenvrti, sp. nov. (Pl. I, fig. 22.) 


Another specimen to be described is a maxilla found by Mr. Cole- 
nutt in Bed 5 at King’s Quay, during a visit to the locality with the 
present writer in 1896. This maxilla, which is now in the Museum 
of Practical Geology, was perfect when found, but broke in pieces 
and lost many of its teeth in drying; it is 110 mm. in length: that 
is, nearly as long as Mr. Clement: Reid’s specimen from Hamstead ; 
butit is much more slender, and the upper border is nearly straight, 
being interrupted only by a single slight. prominence which marks 
the anterior limit of the supplementary maxilla. The rugosity of 
the outer surface extends from the front tooth for about 43 mm. 
along the dentary margin, and reaches the upper margin of the 
bone only at about the middle of this extent. The other parts of 
the outer surface are nearly smooth. When viewed from below, the 
dentary margin is seen to form a comparatively slight curve, and 
the proximal articular process passes inward at a much smaller 
angle than in the Hamstead specimen; in these respects it more 
nearly resembles the maxilla of Amia calva. 

The teeth are round and inflated at the base; they curve inward 
to end in sharp points; and they form a single row of from 40 to 50 
teeth, gradually diminishing in size from before backward. 

This maxilla being unaccompanied by any other parts ef the 
skeleton, its generic position is uncertain ; yet its close resemblance 
to the maxilla of Amia calva in its more important features makes 
it highly probable that it is closely related to that genus. The 
restriction of the ornamentation to the fore part of this bone, while 
in A. calva such ornamentation is more strongly marked and con- 
fined to the hinder moiety, is sufficient to show that our fossil does 
not belong to the recent species. 

This maxilla differs from that of A. anglica in being more slender 
and less deeply curved, as well as in having only a single slight 
process on the upper margin and more restricted ornamentation. 

Compared with the American fossil forms it is the maxilla of 
Pappichthys plicatus,' figured by Cope, which most nearly resembles 
this British fossil, but the latter differs, not only in being narrower 
anteriorly, but also in having the rugosity altogether in front of the 
supplementary maxilla. 

The maxilla of Amia Kehreri is not known. 

As this King’s Quay maxilla cannot be referred to any recorded 
species, it will be convenient for it to have a name, and it is pro- 
posed to dedicate it to the gentleman who has done such excellent 
work among the Oligocene beds of the Isle of Wight, and to name 
it Ama Colenutte. 


1 Cope, Rep U.S. Geol. Surv. Terr. vol. iii (1884) 4to, pl. iii, fig. 12. 


Nol; 55.] AMIA FROM THE ISLE OF WIGHT. 9 


According to Mr. Smith Woodward’s’ revision of the Amide, 
the genus Ama is restricted to deposits of Tertiary age, although 
closely allied forms are found in Secondary strata. ‘Some of the 
North American species, as we have already seen, are referable to 
Amia, and it seems probable that others will-be found to belong to 
the same genus. In Tertiary times, therefore, Amia, which is 
now restricted to the North American continent, must have not only 
occupied that area, but have extended over a large part of Kurope 
as well. The recorded species may be thus tabulated :— 


Norra AMERICA. 


Recent. Amia calva. Living in North American 

rivers. 

Lo wer Miocene. A, macrospondyla, Cope. Cypress Hills, N.W. Ter- 

ritory (Canada). 
A, Whiteavesiana, Cope. Ei i 

Eocene A, dictyocephala, Cope. South Park (Colorado). 
Amyzon Beds A, scutata, Cope. Bs %y 
(?=Barton Beds). 

Eocene A. depressa, Marsh. Wyoming (U.S.A.). 
Bridger Beds A, Newberriana, Marsh. - 
(?=Bracklesham). A. (Protamia) gracilis, Leidy. . 

A, 5 media, Leidy. pe 
A. as uintaensis, Leidy. - 
A, (Hypamia) elegans, Leidy. a 
A, (Pappichthys) Corsini, Cope. - 
A, 3 levis, Cope. Pe 
A, 2 plicatus, Cope. . 
A, a sclerops, Cope. : ‘5 

Eocene A, of sp., Cope. Windy River. 
Wasatch 
(?= Woolwich Beds). 

EUROPE. 
Lower Miocene. Amia Valenciennesi (Ag.). Puy-de-Déme (France). 
A. macrocephala (Reuss). Kutschlin (Bohemia). 
A. Kehreri, Andreae. Messel (Darmstadt). 
Oligocene. A. longistriata (Winkler). Sieblos (Rhenish Prussia). 
A. oligocenica (Winkler). 4 
A. anglica, sp. nov. Isle of Wight. 
A, Colenutti, sp. nov. i 
Upper Eocene. A, ignota, Blainv. Montmartre (France). 
A. sp. Hordwell (Hants). 
Lower Eocene A, (Pappichthys) sp., Lemoine. Reims (France). 


Suessonian 


(= Woolwich Beds). 


? Brit. Mus. Catal. Foss. Fishes, pt. iii (1895) p. 360. 


10 AMTA FROM THE ISLE OF WIGHT. [ Feb. 1899, 


EXPLANATION OF PLATE TI. 
(Except where otherwise stated, the figures are of the natural size.) 


AMIA ANGLICA, Sp. NOY. 


[Figs. 1-5. Specimen obtained by Mr. Clement Reid from Bembridge Marl 
at Hamstead, Isle of Wight, and now in the Museum of Practical 
Geology. | 


Fig. 1. Vertebra (I), from above; 1a, end view. 
2 ” (IIT), ” ; 2 a, ” 
3. Left maxilla, outer surface; 3a, from below. 
36. Left supplementary maxilla. 
4. Left dentary bone, outer'surface ; 4a, inner surface. 
5. Parasphenoid, fragment with dental area. 


[ Figs. 6-14. Specimen obtained by Mr. G. W. Colenutt from Osborne Beds 
(5) at King’s Quay, Isle of Wight. Colenutt Collection. | 


Figs. 6-10. Vertebre II, VII, IX, XII, & XITI, front view. 

6 GOW ah oe a ey from above. 

11. Premaxilla, front view ; 11a, from below. 

12 & 13. Bones of the head to show sculpturing. 

14. Scale, twice natural size. Only a small piece of the scale is 
preserved ; the outline and striation of the outer surface are 
sbown as an impression on the matrix. 

Fig. 15. Left dentary bone, outer surface; 15a, inner surface. From Bem- 
bridge Marl, Thorness Bay. Colenutt Collection. 


[Figs. 16-18. From Osborne Beds (2 & 5), King’s Quay, Isle of Wight. Colenutt 
Collection. ] 
Fig. 16. Left dentary bone, very small, outer surface; 16a, inner surface. 
7. es 7 ,, showing dentate supplementary splenial still 
attached (*). é 
18. Caudal vertebra, upper surface, with three articular facets ; 
18a, end view; 1846, side view; 18c, from below. 


Figs. 19-21. Scales from Osborne Beds (3), King’s Quay, Isle of Wight. Twice 
natural size. Colenutt Collection. These show the border and granu- 
lation of the under surface ; the impression on the matrix exhibits the 
striation of the upper surface. 


Amté COLENUTTI, sp. nov. 


Fig. 22. Right maxilla, outer surface, from Osborne Beds (5), King’s Quay, Isle 
of Wight. In the Museum of Practical Geology. 


Discussion. 


The Presipent and Prof. H. G. Szztey spoke, and the AurHor 
replied. 


Quart.Journ.Geol. Soc .Vol.LV. PII. 


AT Hollick del et Ith Mintern Bros.imp. 


AMIA FROM THE OLIGOCHE OF THE ISLE OF WIGHT. 


Vol. 55. ] : CONGLOMERATE NEAR MELMERBY. £1 


2. Norz on a ConctomeErate near Metmersy (CumBERLAND). By 
J. E. Marr, Esq., M.A., F.R.S., F.G.S. (Read November 23rd, 
1898.) 


As the task of distinguishing ancient glacial deposits from those 
which have received structures resulting from earth-movements is 
one of considerable interest to the geologist at the present time, it 
may be worth while to record the occurrence of conglomeratic 
deposits in England which show indubitable effects of the action of 
earth-movement, not only on the included pebbles, but also on the 
upper surface of one of the deposits. 

The section to be described is seen in a fell-lane west of Ramps- 
mire Sike, about a mile east-south-east of the village of Melmerby, 
which is itself about 53 miles north-east of Penrith. The deposits 
occur between the Carboniferous rocks and the Lower Palseozoic 
slates; they are spoken of as ‘ Basement-beds.’ and referred to 
the Carboniferous system on the Geological Survey map (New 
Series, Sheet 24), though represented with the chocolate colour 
used for Devonian rocks. There is little doubt that these deposits 
are homotaxial with those of the neighbourhood of Sedbergh, of the 
foot of Ullswater, and elsewhere in and around the Lake District, 
which have been described in the Geological Survey memoirs. As 
the conglomerates of the Carboniferous system containing small 
quartz-pebbles, which are low down in that system, appear to rest 
upon them unconformably, I see no reason why the underlying 
conglomerates should not be representatives of the Old Red Sand- 
stone, with which they were originally compared. 

In ascending the fell-lane from a ford at the bottom of the open fell, 
the ‘ Skiddaw Slates’ are seen in a much shattered condition, and 
are immediately succeeded by about 30 feet of a coarse conglomerate 
with red sandstone-matrix, filled with large pebbles (8 inches in 
diameter). This deposit is roughly stratified, owing to the alter- 
nation of bands containing few pebbles with others in which they 
are abundant; the bands with many pebbles are, however, un- 
stratified. Above this is 20 to 30 feet of sandstone with small 
pebbles, and at the summit of the section a second coarse con- 
glomerate, the pebbles in which, however, do not attain the 
dimensions of those in the lower coarse accumulation. The summit 
of the second accumulation is not exposed. The relations of the 
second mass to the underlying finer deposits of pebbly sandstone 
which is crushed in places are shown in the accompanying figure 

plc). 

Che pebbles consist of fragments of grits, argillaceous strata, and 
volcanic rocks, mainly derived from the adjacent Cross Fell Inlier, 
though some have probably been denuded trom rocks situated at a 
greater distance. They possess the outward form of glacial boulders, 
but a number of them, especially of the fine argillaceous rocks, 


12 MR. J. E. MARR ON A CONGLOMERATE . [Feb. 1899, 


show unmistakable signs of being slickensided, though a few 
scratches are found here and there which it would be difficult, 
if not impossible, to distinguish from glacial strie. The following 
features in connexion with these pebbles are noticeable :— 

(i) The regular parallelism and closeness of the lines, in the 
majority of cases. 

(11) Frequent curvature of the lines. 

(iii) Grains of the matrix often firmly embedded at the ends of 
the groovings. 

(iv) Deposit of mineral films on the grooved surfaces. 

(v) Fracture and frequent faulting of pebbles, the throw of ve 
faults being a fraction of an inch. 

(vi) Sudden commencement and ending of grooves at a fault-plane. 

(vil) Striz on adherent matrix in places. This feature was long 
ago pointed out by Prof. T. McK. Hughes in the case of the pebbles 
of homotaxial deposits near Sedbergh, and its significance was 
insisted on.’ 

(viii) Slickensiding occurring on other planes beneath the surfaces 
of the pebbles. 

(ix) Indentation of the pebbles, as the result of pressure. This 
also occurs in glacial boulders, especially of limestone, but, so far as 
I am aware, not on so extensive a scale as here. 

The pebbles in the two coarse conglomerates show the same 
features, though they are best exhibited on the pebbles of the lower 
accumulation. 


On removing a mass of the upper conglomerate, at the point 2 in 
the section, the rock beneath (a coarse red sandstone with small 
scattered pebbles) was found to be marked with groovings. There are 
two principal sets of these, crossing each other at an angle of 
about 40°. Their directions were not observed, as the block ex- 
tracted was carried for some distance to water before the strize 
were rendered visible. The strie appear to be impressed upon 
crushed rock welded on to the sandstone, rather than upon the sand- 
stone itself. Here again evidences of slickensiding are clear, and the 
parallelism of the striz, their closeness, their occurrence on more 
than one plane, and the development of films over them is clearly 
noticeable. Again, we observe a few scattered striations which it 
would be difficult to separate from true glacial strie. The uneven 
nature of the surface appears to be due to indentation by masses of 
overlying rock. 

It will be noticed that the plane of discontinuity between the 
coarse conglomerate and the underlying rock is absent to the left 
of the section, or rather it curves down into the sandstone, so that 
it is probably a plane produced by differential movement, rather 
than one due to pause during deposition of the strata. The section 
itself yields abundant evidence of the occurrence of differential 


* “Notes on the Geology of Parts of Yorkshire & Westmoreland, Proc. 
Geol. Polyt. Soc. West Riding Yorks, vol. iv (1868), No. 8, p. 570. 


Vol. 55.] NEAR MELMERBY (CUMBERLAND). 13 


movements in the rocks, and similar evidence is furnished by the 
study of the general structure of the district. The exposure is close 
to the great fault which extends in a north-easterly and south- 
westerly direction, and brings the Melmerby Scar Limestone down 
from Melmerby High Scar to Melmerby Low Scar, and minor faults 
are associated with this. 

It is quite clear that most of the groovings on the pebbles and 
on the surface of the sandstone alike are of the nature of 
slickenside-striz, but it is of course possible that the shape of the 
pebbles is due to glacial action, and that any glacial striz which 
may have occurred have been obliterated as the result of earth- 
movements. ‘The great amount of indentation which the pebbles 
have undergone, and the manner in which the surfaces of some 
appear to have been squeezed off in a way which can be imitated 
with partially-hardened putty, suggest, however, that the angularity 
of the pebbles may also be partially or wholly due to earth-move- 
ment occurring after their inclusion in the conglomerates. 


Diagrammatic Section near Melmerby. 


1 = Coarse conglomerate (top not seen). 3 = Laminated sandstone. 

2= Thin clayey parting, with flaky struc- 4 = Sandstone with occasional small 
ture, 1 inch thick, resting on the pebbles. 
striated and polished surface of | 5 =Crushed pebbly rock. 
No. 4. F= Fault (not affecting 4 ?). 


I need hardly say that I have not described this section with any 
desire to throw doubt upon recorded instances of glaciated pebbies 
occurring in ancient deposits, but rather to furnish geologists with 
a typical case of production of strie by earth-movements on a rock- 
surface, and also on the surfaces of pebbles, which may be used to 
contrast with the glaciated deposits. I searched for some time fora 
single pebble which might lead the discoverer to suppose that he 
was dealing with a glaciated stone rather than a slickensided one, 
but could not find one that was likely to mislead anyone conversant 
with the results of glacial action. This might perhaps be done in the 
case of a deposit in which the pebbles were less fitted to receive and 
retain extremely fine markings, but the variety of rocks represented 
among the pebbles of the Melmerby conglomerate renders it 
doubtful, though I was unable to discover any limestone-pebbles in 
the accumulation. 

In conclusion, I may state that the specimens exhibited to the 
Society will be placed in the Woodwardian Museum. 


14 MR. J, E, MARR ON A CONGLOMERATE [Feb. 1899, 


Discussion. 


Sir A. Gr1k1z, being called upon by the President, remarked that 
not having any acquaintance with the locality or the specimens 
described by the Author, he hardly felt himself in a position to 
offer any remarks upon them, but lest his silence should seem to 
imply any want of appreciation of the interest and ingenuity of the 
paper, he would gladly admit that in his opinion the Author had 
completely proved the point sought to be established. The peculiar 
features of the conglomerate described in the paper were obviously 
due to earth-movements, and not to glacial action. At the same 
time, while frankly admitting the explanation of the case now 
brought forward, he held that conclusive evidence had been obtained 
of glacially-striated boulders in old geological deposits. Instances 
of these had in recent years been brought before the Society, and 
while he accepted them, he was also prepared to believe that 
innumerable examples might be adduced in which the stones in 
conglomerates had undergone striation in situ by earth-movements, 
and had thus acquired a most deceptive resemblance to boulders 
smoothed and striated by ice. 

Dr. W. I. Branrorp said that if anyone had produced the speci- 
mens on the table as evidence of glacial action, the Author would 
probably have been sceptical and would, in the speaker’s opinion, 
have been quite justified in his want of faith, The occurrence of 
boulders and pebbles embedded in a fine silt was better evidence of 
glacial action than scratched surfaces, and it was upon the former 
that the belief in a Carboniferous glacial period in the Southern 
Hemisphere and India was originally founded. ‘The speaker did not 
‘think that there was any similarity between the surfaces produced 
by wind-action and ice-action respectively. 

Prof. Sortas agreed with the Author’s interpretation of the 
markings exhibited. They were evidently rutsch-strie and slicken- 
sides, and presented no unusual characters. There should be no 
difficulty in the present state of our knowledge in distinguishing 
between such phenomena and glaciated surfaces. On the peninsula 
of Howth, near Dublin, projecting knolls of rock bore markings of 
both kinds, those due to earth-movements and those resulting from 
the movement of ice; but it was always possible to discriminate 
between them. 

Prof. Warts found it difficult to conceive how any conglomerate 
which had passed through earth-movement could escape having its 
pebbles striated. Less stress was now being laid on the value of 
striz to indicate former glacial action, and perhaps the time was 
coming when less importance would be attributed to the shape of 
the fragments and their derivation from a distant source. 

Mr. H. W. Moncxton thought that the specimens on the table 
could scarcely have been supposed to furnish evidence of glacial 
action, whether taken singly or all together. He referred to a recent 
paper in which evidence in favour of glacial action in Paleozoic 


Vol. 55. | NEAR MELMERBY (CUMBERLAND). 15 


times had been adduced, and remarked on the great strength of the 
body of evidence laid before the Society on that occasion. 

The Rev. J. F. Brake said that the Author seemed to have a 
theory that the surface-features of the stones he exhibited were due, 
not to glacial action, but to earth-movements. This theory would 
be more easily accepted if the Author could state in what direction 
the movement was supposed to have taken place, what relation it 
had to the direction of the markings on the stones, and what evi- 
dence there was in the neighbourhood of movement having taken 
place in that direction. 

The Presipent, Prof. H. G. Sretey, and Mr. E. J. Garwoop also 
spoke. 

The AvrHor, in reply, stated that he had brought the case forward 
simply as an example to which appeal might be made in future 
discussions, as showing exceptionally good indications of the various 
features produced by slickensiding. 


16 PROF. T. W. BE. DAVID & MR. E, F. PITTMAN [Feb. 1899, 


3. On the Patmozorc Rapiorarran Rocxs of New Sourn WaAtzs. 
By Prof. T. W. Enczeworte Davin, B.A., F.G.S., and E. F. 
Pirrman, Esq., Government Geologist, N.S.W. (Read November 


9th, 1398.) 
[Puates II-VII.] 
ConTENTS. 
Page 
TL. AmitrodMetion. 0 <cececanecete,cnecemspnesacens werdereea. sere 16 
DE. uO@alities: 5.06 -02225: nate oes octane enone ee ais Mee EE ie 
III. Stratigraphy of the Radiolarian Rocks .................. 18 
TV.. Chemical/Compostiion. | p...2.c20 351i saranses-ume eee eeaepeee 31 
V,, “Microscopie Ciarncters seecuscowaceonmcasonteseneesneeenst 33 
VE. Conclusioma’ Gelith Ag its sctte ose stants nemeneee tee eeene 36 


I. Inrropvuction, 


Tue discovery of casts of radiolaria in Devonian rocks in New 
South Wales was made by one of us in 1895.) It resulted from a 
systematic microscopic examination of some of the red Jaspers of 
New South Wales, in the belief that they were very possibly of 
deep-sea origin, and therefore likely to contain radiolaria, as was 
suggested by the field-evidence, as interpreted elsewhere by one of 
us.” At first only chalcedonic casts of radiolaria were observed in 
the jasper. 

Early in 1896 one of us (T. W. E. David), when on a visit to 
England, was shown, through the courtesy of Mr. J. J. H. Teall, 
F.R.S., a number of carefully-prepared micro-sections of the Ordo- 
vician (?) radiolarian cherts from Mullion Island, off the coast of 
Cornwall, and from the Culm of Devon, as well as from the red 
jaspers of the Antarctic Continent. A collection of radiolarian 
rocks was also contributed by Dr. Hinde, chiefly from the Culm of 
Devon and the Ordovician (?) of Mullion Island, for comparison with 
Australian rocks; and this collection subsequently proved of great 
value in identifying the radiolarian rocks about to be described 
from New South Wales. Work on these latter was resumed at the 
University of Sydney during 1896, with the result that the black 
cherts of Jenolan were found to yield better results than the red 
jaspers of the New England District of New South Wales. 

In September of the same year one of us (T. W. E. David) found 
that at Tamworth, in New South Wales, certain lenticular beds of 
siliceous limestone were not only composed chiefly of radiolarian 
tests, but also contained numerous forms with the original siliceous 
skeleton in a fair state of preservation, as was obvious from an 
examination of the weathered exterior with a pocket-lens. <A 
preliminary note on this discovery was published in the Proceedings 
of the Linnean Society of New South Wales. ? 


1 Proc. Linn. Soc. N.S.W. ser. 2, vol. xi (1896) p. 561. 
2 Thid. ser. 2, vol. viii (1893) p. 594. 
3 Ibid. ser. 2, vol. xi (1896) pp. 553-57 & pls. xxxvil—xxxviil. ’ 


Vol. 55. | ON PALHOZOIC RADIOLARIAN ROCKS IN N. S. WALES. Le 


A collection of specimens of the radiolarian limestone was 
forwarded to Dr. Hinde for specific description. The Second Coral- 
boring Expedition to Funafuti last year somewhat delayed the 
collecting of further evidence, though the discovery was made (by 
E. F. Pittman) that Lepidodendron australe occurred in situ in the 
radiolarian series. At the beginning of this year (1898), however, 
we were enabled to pay three short visits to the locality, and 
found that radiolaria were by no means restricted to the thin bands 
of lenticular siliceous limestone, but were distributed in numbers 
so vast throughout the jointed claystones (the prevalent sedimen- 
tary rock in the district) as to constitute perhaps half their bulk. 
The thickness of the whole Radiolarian Series was estimated at 
about 9260 feet, inclusive of the submarine tufts. The discovery 
that so enormous a thickness of Paleozoic rocks, previously con- 
sidered to be either unfossiliferous or to contain fossils only at wide 
intervals, has been built up very largely of tests of radiolaria, is 
obviously of considerable interest from the stratigraphical as well 
as from the paleontological point of view. 


II. Locatrrres. (See Map, Pl. IT.) 


(1) Bingara.—tThe farthest point north to which radiolarian 
rocks have as yet been traced in New South Wales is a spot on 
the Keira road, about 3 miles east of Bingara. These strata were 
examined by Mr. G. A. Stonier, F.G.S., and one of us in 1890, 
and the first radiolarian casts were observed in some thin sections 
of these rocks, prepared at the University of Sydney some years 
later. 

(2) Barraba.—This locality is about 30 miles south of the pre- 
ceding, and 60 miles north of Tamworth. 

Radiolarian casts have been observed in thin slices, prepared as 
above from specimens of jasper collected here by Mr. G. A. Stonier 
and one of us. 

(3) Tamworth.—The locality where the radiolarian rocks, in 
this neighbourhood, appear to be most abundant is near the southern 
extremity of Tamworth Temporary Common, at the quarry shown 
in Pl, VII. MRadiolarian rocks have, however, been traced by the 
authors from the point marked 10, in Pl. III, to the garnetiferous 
limestone in the same section, a distance of 3 miles, measured from 
west to east. They are also well shown in cuttings of the Great 
Northern Railway south-east and east of Tamworth, between the 
185- and 190-mile posts. Northward they have been traced con- 
tinuously to Moor Creek, a distance of 6 miles. There can be 
very little doubt, however, that the belt of radiolarian rocks is 
continuous from Tamworth through Barraba to at least as far north 
as Bingara, a distance of 85 miles. 

(4) Jenolan Caves.—This locality is situated about 67 miles 
due west of Sydney, and about 200 miles south by west of Tam- 
worth. The radiolarian casts occur there in vast numbers, chiefly 


Oe d.G. Si No. 217. c 


18 PROF, T..W. E. DAVID & MR. E, F. PITTMAN [Feb. 1899, 


on the western side of the cave-limestone. Obscure traces, however, 
of radiolarian casts may be observed in the shales east of the caves, 
and underlying the limestone. The radiolarian rocks have been 
traced for at least 7 mile west of the caves, the best sections being 
exposed in McKeown’s Creek, and for about 1 mile eastward to 
Inchman’s Creek. As it is still uncertain whether the Jenolan 
limestone is of Silurian or of Devonian age, it may be premature as 
yet to attempt its correlation with the Tamworth beds. If it be 
homotaxial with them, the radiolarian rocks will be proved to have 
a range of at least 285 miles, from Jenolan on the south to Bingara 
on the north. 


III. SrratigRAPHy OF THE RADIOLARIAN Rocks. 


(i) In the neighbourhood of Bingara and Barraba there is a 
remarkable similarity in the lithological character and mode of 
occurrence of the radiolarian rocks. They consist of jointed clay- 
stones, of a dark bluish-grey colour at some depth from the surface, 
weathering yellowish-brown, with very numerous interstratified beds 
of submarine tuff and thick bands of coral-limestone. 

So far as observed, the strata are all more or less fine-grained, 
the individual particles composing the rock being as a rule not more 
than 0:05 mm. in diameter, with the exception of the radiolaria, 
whose diameter ranges from about 0°125 up to about 0-41 mm. 

A conspicuous feature in the geology of this district is a belt of 
serpentine, from 7 to 4 mile wide, extending south-south-east from 
Bingara to the coast at Port Macquarie, a distance of 180 miles. 
A zone of red and dark-grey or greyish-white jasperoid rock, several 
hundred feet in thickness, runs parallel with the serpentine-dyke on 
its E.N.K. side. It is not yet certain that the jaspers owe their 
silicification or their red colour to contact-metamorphism induced by 
the serpentine-dyke. That the latter is intrusive is proved by the 
nature of its junction with the sedimentary rocks, as seen at Barraba 
and Bingara, where small veins and tongues of serpentine, offshoots 
of the main mass, may be observed intersecting and penetrating the 
sedimentary rocks. 

That this dyke has materially influenced the metalliferous 
character of the neighbouring sedimentary rocks is proved by the 
existence of numerous gold-bearing veins in close proximity to it, 
for a considerable distance along its course. The gold-veins have 
been worked at Bingara, Woodsreef, Ironbark, Crow Mountain, 
Ti Tree, Bowling Alley Point, Hanging Rock, near Nundle, etc. 
With regard to the red colour of some of the jaspers, the fact should 
be mentioned that near Ironbark, in the Barraba district, there are 
beds of hard red clay-shales, interstratified with the jasperoid 
series, which appear to owe their red colour to hematite formed 
contemporaneously with their deposition, and therefore prior to the 
intrusion of the serpentine-dyke. The serpentine appears to have 
resulted from the alteration of an ultrabasic rock, rich in olivine 


Vol 55-] ON PALHOZOIC RADIOLARIAN ROCKS IN N. 8S. WALES. 19 


and chromite, as described by Mr. W. Anderson, late of the Geo- 
logical Survey of New South Wales.’ 

In the Barraba and Bingara districts radiolaria are present in 
the form of chalcedonic casts in the red jaspers and in the dark- or 
light-grey jasperoid claystones. They are in the best state of pre- 
servation in the former, particularly in those varieties which are 
most opaque, and which have suffered least from secondary silicifica- 
tion. The thickness of some of the belts of red jasper amounts to 
about 100 feet, but the average thickness would perhaps be con- 
siderably less. The individual beds of which the jaspers are formed 
are apparently thin, but owing to much superinduced lamination, 
parallel to the bedding-planes, their original thickness is difficult to 
ascertain. 

The radiolarian jaspers and claystones of Bingara and Barraba 
are, as a rule, inclined at a high angle, with a prevalent strike of 
N. 20° to 30° W. In the neighbourhood of Ironbark, near Barraba, 
the dip is 80° to 90° north-north-east. The series near Barraba is 
not much folded. 

As regards the downward limit of the Barraba and Bingara 
series, no basal beds are at present known, but detailed geological 
mapping of this large and sparsely-populated area has not as yet 
been attempted. Neither has any definite upward limit hitherto 
been discovered, though it is probable that the series underlies the 
bulk of the Lepidodendron ausirale-beds. No physical break 
between the radiolarian and the Lepidodendron australe-beds, how- 
ever, has as yet been traced. | 

With regard to macroscopic fossils, it is doubtful whether any 
which have been described from these districts belong to the jasperoid 
series of Bingara and Barraba. Mr. G. A. Stonier has referred to 
the occurrence of fossils at Crow Mountain, near Barraba. These 
have been determined by Mr. W. 8. Dun, as follows * :— 

‘Crinoid stems; Phellipsia sp.; Henestella; Polypora or Phyllopora; 
Rhombopora (?); Spirifer; Syringothyris cf. cuspidata, Martin ; 
Strophomena ef. rhomboidalis, var. analoga, Phill.; Orthis resupi- 
mata, Martin (?); Orthotetes (?); Productus, several species.’ 

As, however, the rocks containing these fossils occur on the 
W.S.W. side of the serpentine-dyke, and differ somewhat in litho- 
logical character from the jaspers, which are so dominant a type 
on the E.N.E. side, there is reason for assuming that they may 
belong to a newer series, the dyke possibly marking the site of 
a fault, with a downthrow to the west-south-west. 


) (Gi) Near Tamworth the radiolarian rocks are developed on a 
grand scale. Their total thickness, including that of the inter- 
calated tuffs, as measured by us, amounts to perhaps 14,220 feet. 
There are good grounds, however, for supposing that the beds 
have been duplicated by a great fault; but even on this hypothesis 


t Ann. Rep. Dep. Mines N.S.W. for 1888 [1889] pp. 179-182; 7bid. 1889 
[1890] p. 230. 
2 Ibid. 1895 [1896] p. 168. 
c2 


20 PROF. T. W. E. DAVID & MR, E. F, PITTMAN [Feb. 1899, 


the thickness would still amount to about 9260 feet, and no upward 
or downward limit to the series has yet been discovered. The 
details are shown in the accompanying section (Pl. III). The height 
attained by the beds above sea-level varies from 1220 to 2570 feet. 

With the exception of some wide strips of post-Tertiary alluvium 
along the course of the Peel and Cockburn Rivers, the sedimentary 
rocks of this district are wholly Paleozoic. The series examined by 
us is bounded on the north-east by a large mass of intrusive granite. 
The granite is ternary, passing near its junction with the sedimentary 
rocks into an aplitic type. Sphene has lately been observed by 
Mr. G. W. Card, Mineralogist to the Geological Survey of New 
South Wales, in part of this granite on the Government Tobacco 
Farm, near Tamworth. It occurs in comparatively large crystals, and. 
frequently idiomorphic, in abundance as an accessory mineral. The 
rock also contains hornblende as well as biotite. Atthe boundary of 
the granite, as shown near the eastern end of the section (Pl. IIT) 
the sedimentary rocks dip underneath it, which is suggestive 
of the massif having the structure of a laccolite, or possibly that 
of a huge sill. In close proximity to its margin is a bed of 
limestone, varying from 50 to over 100 feet in thickness. Traced 
northward to Moor Creek its thickness increases considerably, and 
in places must be about 1000 feet. 

The limestone has been converted by contact-metamorphism into 
a coarsely crystalline, saccharoidal marble, with an abundant fibrous 
white mineral (tremolite?) and garnets. Nearly all traces of the 
structure of the organisms which have contributed to form this 
limestone have been obliterated through metamorphism, with the 
exception of some imperfectly-preserved specimens of corals refer- 
able to the Favositide, including Favosites, Alveolites alveolaris, 
an external cast of Diphyphyllum, some badly-preserved casts of 
what Mr. W. 8. Dun considers to be probably Pentamerus, and. 
abundant casts of crinoids. This limestone-bed has been folded into 
an anticline, the arch of which has subsequently been removed by 
denudation. On following the bed northward for a mile from its 
bold outcrop west of Carmichael’s homestead, we found that it 
gradually bent round in a curve towards the west and south until 
it ultimately assumed a reversed dip which was west-south-west 
at 55° where it crossed the line of section. The strata intervening 
between this limestone-bed and the thin bed of radiolarian lime- 
stone marked G (PI. ITI) consist chiefly of claystones, black cherts, 
radiolarian limestones, and tuffs, similar to those constituting the 
greater part of the sedimentary rocks in the section at Tamworth 
Common about to be described. The aggregate thickness of these 
strata amounts to about 4150 feet. 

The claystones are similar in lithological character to those 
above mentioned near Bingara and Barraba, but the radiolaria 
appear to be better preserved in the Tamworth rocks. Red jaspers 
are not represented. As a general rule, the radiolarian rocks 
are sufficiently soft to admit of being scratched by steel. The 
section above the limestone, if taken in ascending order, shows: 


Vole 55-| ON PALHOZOIC RADIOLARIAN ROCKS IN N. S. WALES. 21 


about thirteen beds of thin lenticular limestones, each from 6 to 
over 12 inches thick, the total thickness of the intermediate strata 
being approximately 1000 feet. Several of these limestones are 
largely formed of radiolarian tests, or their comminuted and altered 
remains, but some are so altered as to have had almost all traces 
of the radiolaria obliterated. That originally they were largely 
formed of radiolaria may be inferred from their close resemblance 
to similar beds in the same series, from obscure spherical casts 
contained in them of the same size as those of undoubted radio- 
larian casts in the adjoining rocks, and from the abundance of casts 
of radiolaria in the cherts and claystones with which the thin 
limestones are interstratified. 

The black cherts contain very numerous casts of radiolaria, at 
the rate, approximately, of about one million tothe cubicinch. As, 
however, this part of the section cannot be so satisfactorily worked 
out as in the area where, according to our interpretation of the 
section, the beds are repeated by the great fault which runs 
through Tamworth Common, further description may be reserved 
until the Tamworth Common section is discussed. The beds of 
radiolarian limestone are lettered H to T, inclusive, along the 
line of section (Pl. III). All these limestones agree in general 
characteristics. They are dark bluish-grey at some depth from the 
surface, but weather into a soft, brownish, earthy material re- 
sembling ‘ rotten-stone ’ or Bath brick, and can be readily crumbled 
between one’s fingers. With the aid of a pocket-lens radiolarian 
tests may be seen in abundance in some of the weathered crusts. 

The total thickness of strata represented from the top of the 
garnetiferous limestone to the radiolarian limestone-bed marked H 
is about 1400 feet. Between H and the next radiolarian limestone- 
bed, marked G, there is a thickness of about 2750 feet of cherty 
claystones and tuff. Every specimen so far examined shows that 
the claystones are largely formed of radiolaria. Possibly some 
lenticular beds of radiolarian limestone in this part of the section 
may have escaped our notice. The maximum thickness of G is 
about 1 foot. It is lenticular and intermittent, dipping 48° south- 
west. 

A thickness of about 50 feet of cherty claystones separates 
the limestone-bed G from that next above it, F. Indistinct plant- 
remains, together with Lepidodendron australe, were discovered 
by us in a bed 3 inches thick in the claystones. The bed F is 
similar in nature to G, and is from 6 to 12 inches thick. 

Next above F comes a thickness of 245 feet of claystones, 
succeeded by a bed of tuff, in which numerous well-preserved 
specimens of Lepidodendron australe can be seen in situ. These 
were first noticed by Mr. F. Blatchford (who assisted us in the 
examination of this district) in some talus formed of fallen 
fragments of the tuff. Such specimens are generally within an 
inch or so of fragments of the radiolarian claystone entangled in the 
tuff. In some cases impressions of ZL. australe can be seen in 
the entangled claystone-fragment ; in others the cast is completely 


“ities 


3 feet, and the length 4 feet. | 
adiolarian cherts. | 


d portions represent the r 


G, 34 ee ty > 
Yj 7 YUH 


Vj 


ght of the section figured here is 


The shade 


tYHy 
UY 
GY 


[The hei 


"sng ouiwnuiqns pup 
sp1ayo UDLIMOUpD. fo aLngHrULaQUe ay? HurDusnpe “(AL "GCAT) VOU YROMUD], 10 hspngy ua wonoag 


Vol. 55.] PALMOZOIC RADIOLARIAN ROCKS 1N NEW SOUTH WALES. 23 


surrounded by the tuff. Unweathered impressions of Lepidodendron 
australe retain some carbon, referable obviously to the material of 
the original plant. These casts are about 28 mm. wide, 150 to 
300 mm. long, and 3 to 25 mm. thick. A score or so were observed 
by us, as wellasa cast of a fluted stem, perhaps a calamite, 150 mm. 
long and 25 mm. wide. Several of these specimens were observed 
im situ in the undisturbed tuff, at its outcrop on the precipitous 
slope of the hill. 

The sedimentary claystones and the tuffs appear to be so inti- 
mately mingled together at this spot that it is difficult in places to 
define their original boundaries without the aid of thin micro-slides, 
a number of which have been prepared. A featuré which we 
would specially desire to emphasize is the occurrence of the radio- 
larian limestone E (see Pl. IIL) only 6 inches above the stratum 
which contains so many examples of ZL. australe, and moreover, in 
some examples from this horizon, chalcedonic casts of radiolaria 
abound in the same. rock as that which contains L. australe. 

The thin tuff-beds and intervening cherts with which the L. aus- 
trale is associated at the radiolarian limestone-bed E are about 
7 feet thick. Between E and the next limestone-bed, D, there is 
a thickness of about 1960 feet of the usual claystones, cherts, and 
tuffs, with probably a few lenticular bands of radiolarian limestone, 
which we in our traverses failed to strike. The radiolaria in some 
of these cherts are of comparatively large size, up to 0°36 mm. in 
diameter, as shown in micro-slides Nos. 274 & 628. 

An interesting feature in this part of the section is the occur- 
rence of fine conglomerates, with which is associated a curious dark 
greenish-brown tuff containing rounded blocks of eruptive rocks 
from a few inches up to over a foot in diameter. 

With regard to its occurrence in the field, this rock appears to 
occupy the uppermost position in the group of Paleozoic rocks near 
Tamworth. It occurs in considerable thickness, capping a hill which 
separates the mouth of Long Gully from that running through 
Cleary’s selection, about 1 mile north-east of Tamworth Railway- 
station. A good section is also exposed in the ridge about 7 mile 
east of the last-mentioned locality, and the same rock is visible as a 
thin capping on the range about 4 mile north. In the second locality 
there is evidence suggesting that what at first sight appear to be 
bedding-planes are really examples of well-developed and regular 
jointing, for crossing these lines nearly at right angles are some- 
what irregular but distinct pebble-beds in which the pebbles vary 
in diameter from 6 to 25 mm. The joint-planes dip 40° south- 
_ south-east, while the pebble-bands dip west 30° south to south-west 
at about 22°. Included in the matrix are the blocks of hornblendic 
quartz-felsite, over a foot in diameter, already mentioned. The 
pebble-beds cannot be broken or separated from the overlying and 
underlying rocks by any defined planes of deposition and, as above 
stated, their course is not absolutely regular. 

At Cleary’s Hill, more than } mile west of the spot just described, 
a similar rock of agglomeratic appearance dips south 20° west at 22°, 


24 PROF. T. W. E. DAVID & MR, E. F, PITTMAN [Feb. 1899, 


whereas the cherty claystones, immediately underlying it, dip south 
7° to 10° east at 23°. The matrix of this rock is dark greenish-grey 
to greenish-brown, and numerous, pebble-like, rounded to angular 
fragments are enclosed in it, the fragments ranging up to 9 inches 
in diameter. Pieces of radiolarian cherty claystone and limestone, 
mostly angular, and measuring about 7 inches by 5, with thin 
tuffs, are included in the matrix. In addition to these enclosures, 
there are numerous pebbles, round or oval, though not necessarily 
waterworn. Some of these are porphyritic andesites, such as the 
rock described in micro-slide No. 621 (p. 36), and one of them 
is distinctly amygdaloidal. The whole rock has very much the 
appearance of a volcanic agglomerate. Its matrix is very like 
that of the 22-yards tuff at Tamworth Common, but contains 
rather more augite, and in addition aggregates of calcite. A 
chemical analysis of this rock is tabulated on p. 32. Probably this 
agelomerate-like mass at Cleary’s Hill is part of the mass seen in 
the hill some 500 yards farther east, and it is closely related to, if 
not absolutely identical with, the similar rock capping the spur more 
than 4 mile north of Cleary’s Hill. 

At the easterly outcrop, there can be little doubt, in the opinion of 
one of us (T. W. E. David), that the small pebbles are of waterworn 
origin. Possibly they may represent the basal conglomerates of 
a newer formation, such as the Carboniferous. Whether the large 
blocks of quartz-felsite and the smaller fragments of porphyritic 
andesite owe their rounded surface to corrosion or erosion is doubtful. 
Equally spherical blocks, owing their roundness to corrosion in an 
eruptive magma, have been observed at the Pennant Hills Basalt 
Quarry, near Parramatta.’ Whatever may have been their mode of 
origin, we do not consider the pebbles and rounded blocks to belong 
to the radiolarian series. 

From the bed just described up to the outcrop of the massive lime- 
stone seen in Tamworth Temporary Common the strata are still 
cherty radiolarian shales, with one bed of lenticular radiolarian 
limestone marked D in Pl. III, and another marked C, in the 
same plate. There are besides a great many beds of tuff, one of 
the most conspicuous of which is shown at T(a)in Pl. III. The 
thickness of beds, including tuffs, from D to C is about 1480 feet ; 
the radiolarian limestone C is about 2 feet thick. The thickness 
of strata from C to the top bed seen east of the great fault, and 
adjoining the coral-limestone, is about 1450 feet. 

A third horizon for Lepidodendron australe occurs in this division 
of the beds: several well-preserved specimens being discovered by 
us in Porter’s Gully, a locality for these fossils which was pointed | 
out tous by Mr. Donald A. Porter, of Tamworth. At the quarries, 
west of the coral-limestone near B (Pl. ILI), radiolaria occur in 
abundance in soft clay-shales, in which they show clearly to the 
unaided eye as small round grains, and with a pocket-lens the 
reticulate structure of the tests can be distinctly seen on freshly- 
broken or on weathered surfaces. These beds are minutely lami- 

T See Journ. Roy. Soc. N.S.W. vol. xxvii (1893) pp. 401-406. 


Nol.5 5. ON PALHOZOIC RADIOLARIAN ROCKS IN N.S. WALES. 25 


nated, the lamine of deposition being about 1 mm. thick. The 
base in which the tests occur is very fine-grained, the particles 
being from 0:025 to 0:05 mm. in diameter, and -in places the 
cherts and clay-shales are streaked and spotted with finely-divided 
carbon. ‘That the base is not wholly siliceous, as it would be if 
entirely derived from the breaking-down of the radiolarian tests, is 
rendered probable by the chemical analysis of radiolarian shale 
collected by us near Tamworth Common, and apparently exactly 
similar to that now under consideration, which shows that the shale 
contains 15 per cent. of alumina. 

The massive coral-limestone crops out in Tamworth Temporary 
Common. A good section of this and of the overlying cherts, 
claystones, and radiolarian limestones may be studied in the quarry 
on the left bank of the small creek which flows through this part 
of the Common. A section of these and of some of the tuff-beds 
is shown in Pl. III. (Numerous smaller intervening beds have 
been omitted.) 

The limestone has a general westerly to west-south-westerly dip 
at 45° to 57°, and, so far as can be judged, is about 140 feet thick at 
this point. It thickens, however, considerably northward, being about 
1000 feet thick in the parish of Woolomol, some little distance to 
the north-north-west. The colour varies from white to bluish (dark) 
grey. It contains corals, hydrocorallines, and in places crinoids, in 
great abundance. Among the hydrocorallines Stromatoporella is 
very common, while among the corals the following predominate :— 
Pachypora and Alveolites alveolaris, both extremely abundant ; 
Heloolites, plentiful; as well as several species of Syringopora, 
Diphyphyllum Porteri, and Oystiphyllum. 

A comparison of the section here with that described at the 
eastern end, commencing with the garnetiferous limestone, has led 
us to the conclusion that the two sections are identical, and that 
consequently there must be a great fault throwing easterly towards 
the granite-massif. It is this fault which has caused a repetition 
of the beds, and its throw must amount to 9000 feet. The suppo- 
sition as to the existence of the fault is confirmed by the structure 
of the limestone-bed at the top of its outcrop, as it is sharply folded 
over, so as to dip steeply towards the east—that is, towards the 
fault-plane, as shown in Pl. III. 

The arguments in favour of this fault are chiefly as follows :— 

(1) The fact that the limestone on the eastern side of the anti- 
cline dips eastward and that a little farther east the strata dip 
persistently westward, and yet the limestone does not reappear at 
the spot where it should do so if the strata, ¢. g., of the anticline 
formed a trough. On the contrary, the strata east of the anticline, 
for a considerable distance, do not contain any thick bed of lime- 
stone, but consist chiefly of claystones, tuffs, with occasional thin 
bands of radiolarian limestone for about 22 miles eastward, where 
the garnetiferous limestone (a repetition, according to our view, of 
the coral-limestone) is rzached near the eastern extremity of the 
line of section. 


26 PROF. T. W. E. DAVID & MR. E, F, PITTMAN [Feb. 1899, ° 


(2) The occurrence of two very similar beds of limestone, con- 
taining the same species of fossils, at Moor Creek and in the parish 
of Woolomol. ‘As these two outcrops of what appears to be the 
same bed of limestone are now about 3 miles apart, and there is no 
evidence of the existence of a fold between them, the most reason- 
able explanation of the severance of these outcrops is that it has 
resulted from faulting. 

(3) The fact that the radiolarian limestones, and also the black 
cherts above the garnetiferous limestone at the eastern end of the 
section, appear to be repeated in that part of the section which lies 
west of the coral-limestone at Tamworth Common, would seem to 
require the existence of a fault for its explanation. 

(4) The fact that hitherto Lepidodendron australe has never been 
observed in beds stratigraphically as low as the horizon of the 
Burdekin Limestones (Middle Devonian), to which the Tamworth 
limestone probably belongs; and the fact that, unless the existence 
of this fault be admitted, it must follow that the Lepidodendron aus- 
trale between D and H, and also at E (PI. IIL), and that between 
F and G are stratigraphically tar below the horizon of the Tamworth 
coral-limestone. 

If, however, our interpretation of the section be correct, the 
original horizon of the Lepidodendron australe-beds was above, and 
not below that of the coral-limestone. 


Black chert is developed in the Tamworth Common section 
between Nos. 1 & 4 radiolarian limestone-beds: it merges above 
and below into cherty shales. A chemical analysis of this chert 
is tabulated on p. 32 (No. 1234). Although, as seen under the 
microscope, it appears to contain a number of minute carbonaceous. — 
streaks, the chemical analysis shows only ‘minute traces’ of 
organic matter, and a specimen of cherty shale taken from an 
adjoining spot yielded only °86 per cent. of organic matter. 7 

The radiolarian tests can be distinguished readily on the brown 
crust, a result of weathering, which coats the radiolarian limestone ;. 
and, on etching out the lime from unweathered portions of the 
limestone, the original siliceous tests of the radiolaria are exposed 
to view, frequently in a good state of preservation, especially as: 
regards the medullary test. 

The rest of the section westward does not call for special com- 
ment, being formed of typical radiolarian claystones and cherty 
shales, with three beds of radiolarian limestone. 

All these beds are a repetition, according to our view, of the 
strata described at the eastern end of the section. The total 
number of lenticular beds of radiolarian limestone observed by us 
east of the great fault amounts to eighteen, and it is probable, 
as the limestones are thin and lenticular, and the section some- 
what rubbled over in places, that several beds have escaped our 
observation. 


Vol. 55.| | ON PALAOZOIC RADIOLARIAN ROCKS IN N. 8. WALES. 27 


Sections on the Great Northern Railway near 
Tamworth. 


In cuttings of the Great Northern Railway, along the course of 
the valley of the Cockburn River, south-east and east of Tamworth, 
sections of the radiolarian shales and tuffs are well shown. The 
first cutting east of Tamworth, near the 188-mile post, is in laminated 
radiolarian shales dipping south 25° west at 50°; beyond this, other 
cuttings, with extended interspaces where the rocks are not shown, 
reach nearly to the 190-mile post, and at a short distance from 
this point the granite comes in. The position of the cuttings is 
shown in the accompanying map (Pl. II), and a section, drawn to 
scale, has been prepared, which illustrates the character of the beds 
passed through in the cuttings for a distance of 1 mile 20 chains 
(Pl. IV). The radiolarian rocks are almost wholly clay-shales and 
mudstones, varying in tint from brownish-grey and olive-brown to 
dark grey and black. They are usually soft and finely laminated, 
and for the most part they occur as thin bands from 2°5 to 15 
or even 30 em. thick, which alternate between beds of tuff of 
the same or greater thickness. The shales sometimes pass into 
chert in contact with the tuffs, and cherty masses occasionally occur, 
enclosed within the tuff-beds. The shales contain radiolaria in 
great abundance, and they can be distinguished even without a 
lens. 

On at least four horizons in the railway-cuttings, there are 
abundant plant-remains associated with radiolaria in the shales. 
On two horizons the plants are certainly Lepidodendron australe, on 
another the Knorria condition of the same plant, and on the fourth 
horizon probably Knorria also. These plant-remains are not 
merely isolated specimens, for they are fairly numerous on the 
horizons where they occur, from three to ten specimens appearing in 
every square foot of the bed. The occurrence of these plant-beds, on 
the hypothesis that they were due to occasional specimens drifted 
far out to sea and then waterlogged, does not therefore apply. In 
two places also along the line of railway we observed clear evidence 
of ripple-marks in the radiolarian rocks. 

' The submarine acidic tuffs exposed in the railway-cuttings are, 
as a rule, evenly bedded, and sometimes finely laminated. Some 
beds are of considerable thickness, others very thin. The tuffs are 
greenish-grey at a depth, while at the surface they weather into a 
reddish-brown rock with separation of white veins (of magnetite ?). 
In weathering also the tuffs not infrequently assume the form of 
rude spheroids. Pebbles of eruptive rock up to 7°5 cm. in diameter 
sometimes occur in these tuff-beds, and rarely also they contain 
impressions of plants. 

Though, as a rule, the tuff-beds are regularly and evenly inter- 
bedded with the radiolarian clay-shales, instances are not infrequent 
where these rocks are confusedly intermingled together. An example 
of this is seen in the accompanying reproduction of a photograph 


28 PROF, T. W. E. DAVID & MR. E. F. PITTMAN [ Feb. 1899, 


(Pl. VI), showing disturbed masses of radiolarian shale enclosed and 
entangled in a thick bed of submarine tuff. 


With regard to the geological age of the Radiolarian Series at 
Tamworth, as evidenced by fossils other than radiolaria, somei a 
may be formed from the following list, which has been prepared for 
us by the courtesy of Mr. R. Etheridge, jun.—the fossils all occurring 
in the thick coral-limestone. Mr. Etheridge considers that these 
corals represent the Middie Devonian age of the limestone, which 
corresponds with that of the Burdekin Beds of Queensland." 


List of Corals in the thick Limestone of the 
Tamworth District 


(determined by Mr. R. Erueripes, jun.). 


1. Amphipora ramosa, Phill. 


Highly silicified, but not to be distinguished macroscopically from British 
specimens. 


a. Moor Creek. 


2. Diphyphyllum Porteri, Kth. fil. 


An interesting form differing essentially from the known Carboniferous 
species. 
a. ‘Tamworth’ (D. A. Porter). 


3. Diphyphyllum, sp. nov. 


A large robust species, allied to D. arundinaceum, Billings, from the 
North American Corniferous Limestone. 
a. Moor Creek. 


4. Gen. et sp. nov. 


A very peculiar Zaphrentoid coral, in which all the corallites are united 
and surrounded at one and the same level, and in successive tiers, by a 
delicate, plate-like, thecal expansion. 

a. One mile north of Tamworth. 


5. Spongophyllwm, sp. nov. 


A much larger species than the allied Sp. bipartitum, Eth. fil., from the 
Yass district, and with nearly 24 times as many septa. 
a. Moor Creek. 


6. Microplasma, sp. nov. 


A fasciculate and well-marked species of a genus, chiefly Silurian, but 
also found in the Devonian of Germany. 
a. Moor Creek. 


1 Jack & Etheridge, jun., ‘Geol. & Paleont. of Queensland & New Guinea’ 
(1892) p. 47. 

? [It is expected that detailed descriptions of this and the other new forms 
in this list will be published by Mr. Etheridge in Rec. Geol. Sury. N.S.W.] 


Vol. 55.] ON PALAOZOIC RADIOLARIAN ROCKS IN N.S, WALES. 29 


7. Actinocystis (2), sp. nov. 


A large species, allied to A.? Terraregine, Eth. fil., of the Queensland 
Devonian, but possessing a central tabulate area. 
a. Seven miles N.W. by N. of Tamworth (D. A. Porter). 
6. Moor Creek. 


8. Syringopora auloporoides, De Kon. 


Originally described by De Koninck as Devonian, from ‘ Moara’ Creek, 
north of Tamworth, no doubt our Moor Creek. 
a. Moor Creek (D. A. Porter). 
6. Parish of Woolomol. 


9. Syringopora, sp. nov. 


An interesting Syringoporid, of the group of 8S. cespitosa, Goldf., from 
the German Devonian. 
a. Thirty miles north of Tamworth. 


10. Favosites gothlandica, Lam. (?). 


A septate form, which corresponds in every way with this widely- 
distributed coral. 
a. Moor Creek. 
6. Parish of Woolomol. 


11. Favosites basaltica, Goldf., var. nov. 


A variety of a form that otherwise corresponds with this old and well- 
known species. 
a. Parish of Woolomol. 


12. Fawosites basaltica, Goldf., var. nov. 


Another variety of the same, with very fine and delicate corallites. 
a. Beedle’s Freehold, Moonbi. 


13. Pachypora, sp. nov. 


A very large form of the genus, in fact the ine Pachypora known to 
me. To some extent it is, in the form of its calices, intermediate between 
Pachypora and Stridtopora. 

a. Beedle’s Freehold, Moonbi. 


14. Heliolites porosa, Goldf. 


A well-known and typical world-wide Devonian fossil. 
a. Moor Creek. 
6. Parish of Woolomol. 


15. Amplexopora Konincki, Eth. fil. & Foord. 


Identical with specimens from the Devonian of Queensland. 
a. Moor Creek. 
b. Manilla Road, 15 miles from Tamworth (W. Anderson). 


There does not appear to be any break in the sequence of strata 
between the coral-limestone and the Lepidodendron australe-beds, 
and, as already mentioned, radiolaria occur abundantly in the 
same strata as those which enclose Lepidodendron australe.” 


1 Regarding the geological range of L. australe in Hastern Australia, the 
following papers may be consulted :— 


‘Geol. & Phys. Geogr. of Victoria,’ R. A. F. Murray (1887), p. 67; Ree. 
Geol. Surv. N.S.W. vol. ii (1891) pp. 119-1384—‘ Lepidodendron australe, 


30 PROF. T. W. E. DAVID & MR. E. F. PITTMAN [Feb. 1899, 


The general conclusion formed at present is that in Eastern 
Australia Lepidodendron australe, being closely associated with 
Rhynchonella pleurodon, and almost immediately and quite conform- 
ably overlying quartzites containing an abundance of Sporifer 
disjunctus, descends in some cases into Devonian rocks. Its occur- 
rence in the Gympie rocks of Queensland, in association with a 
marine fauna of Carboniferous affinities, proves that it also ascends 
into strata of that age.’ 

The occurrence near Tamworth of JZ. australe in a series con- 
formably overlying a coral-limestone containing a typical Burdekin 
(Middle Devonian of Queensland) fauna is strongly in favour of 
its age being referable to some part of Devonian time, perhaps 
Upper Devonian. The evidence of the marine fossils, other than 
radiolaria, also suggests that the radiolarian rocks of this neighbour- 
hood were formed in Devonian time. If this provisional conclusion 
be correct, it is doubtful whether the Tamworth radiolarian beds 
can be considered homotaxial with those at the Jenolan Caves, 
about 200 miles south by west from Tamworth, already mentioned 
(pp. 17, 18). 


(iii) At the Jenolan Caves, radiolaria occur in the form of chalce- 
donic casts, chiefly in the black cherts and black clay-shales over- 
lying the coral cave-limestone. They may also be seen, though very 
obscurely, in great numbers in the greenish-grey shales which 
underlie the limestone. 

Mr. R. Etheridge, jun.,? has recorded the following fossils as 
occurring in the Jenolan Cave limestone :—Pentamerus Knightiz, 
J. Sow.; Paleoniso Brazieri, Eth. fil.; Lovonema antiqua, De Kon. ; 
a large Favosites; and Tryplasma wellingtonense.* Stromatoporella 
is also abundant. 

Mr. Etheridge considers that the large varieties of Pentamerus 
Knightii are suggestive of a geological age approximating to that of 
the Aymestry Limestone of England. At the same time, he points 
out that this fossil has not yet been identified in any rocks in New 
South Wales as old as Upper Silurian. The fact should also be 
mentioned that no typical Upper Silurian corals and no trilobites, so 
characteristic of the Upper Silurian of New South Wales, have as 
yet been found at Jenolan. No good ground, therefore, exists at 


M‘Coy: its Synonyms & Range in H. Australia,’ by R. Etheridge, jun.; Rep. 
Austr. Assoc. Adv. Sci. vol. iv (1892) pp. 332-337—‘ Occurrence of Lepido- 
dendron near Bathurst, by W. J. Clunies Ross; Proc. Linn. Soc. N.S.W. 
ser. 2, vol. viii (1893) pp. 121-125; Rec. Geol. Surv. N.S.W. vol. iii (1893) 
pp. 194-201 & pls. xvii-xix—‘ Occurrence of Lepidodendron australe (?) in_ the 
Devonian Rocks of N.S.W.,’ by T. W. E. David & EH. F. Pittman; Rep. 
Austr. Assoc. Ady. Sci. Adelaide, vol. v (1893) pp. 397-404 & pl. xv— 
‘Contrib. to Study of Vole. Action in E. Australia, by T. W. HE. David. ; 

1 «Geol. & Palxont. of Queensland & New Guinea’ (1892) pp. 179, 196, ete. 
R. L. Jack & R. Etheridge, jun. 

2 Rec. Geol. Sury. N.S.W. vol. iii (1892) p. 57, and Ann. Rep. Dep. Mines, 
N.S.W. 1892 [1893] p. 128. 

3 Rec. Geol. Surv. N.S.W. vol. iv (1895) pp. 160-162 & pl. xxi, fig. 5, 


Vol. 55.] ON PALHOZOIC RADIOLARIAN ROCKS IN N. 8S. WALES, 31 


present for assigning a greater antiquity to the Jenolan Cave 

radiolarian rocks than to those at Tamworth. At all events, both 

may very well fall within the limits of some part of the Devonian 

Period, though on the whole it is probable, in view of the abundance ° 

of large specimens of Pentamerus Knightw in the Jenolan Cave lime- 

stone, that that rock and its associated radiolarian shales are older 
than the radiolarian shales and limestones of Tamworth. 


With respect to the submarine tuff, Mr. G. W. Card has 
pointed out to us that a number of thin slices of this rock prepared 
under his supervision have exactly the aspect of a felsite-tuff, 
numerous fragments of cryptocrystalline felsite being entangled in 
the holocrystalline or microcrystalline groundmass. The latter is 
composed of broken and corroded crystals of plagioclase, orthoclase, 
quartz, and augite, with occasionally hornblende, and more rarely 
sphene. Small crystals of iron-pyrites are numerous, and grains of 
titaniferous iron sometimes occur; small and large enclosures of the 
radiolarian rocks abound. 

The thickness of the submarine tuff-beds varies from that of a 
mere thread up to about 100 feet or more. At some depth from 
the surface the colour of the tuff is greenish-grey, weathering to 
yellowish-brown or light grey at the surface, and thus contrasting 
strongly with the darker claystones. A chemical analysis of the 
tuff will be found on p. 32. | 

Reference has already been made to the occurrence of casts of 
Lepidodendron australe on three horizons in these tuffs (p. 27), and 
also to the fact that the bed developed at Cleary’s Hill and in the 
spurs to the east and north (pp. 23, 24) has all the appearance of a 
volcanic agglomerate, with large included fragments and pebbles. 


LY. Caemicat Composition. 


The following analyses (p. 32) of the radiolarian limestones, cherts, 
shales, tuffs, and volcanic agglomerate were made by Mr. J. C. 
H. Mingaye, F.C.S., Analyst and Assayer to the Geological Survey 
of New South Wales, from samples collected by us. 

With reference to these analyses, we would comment on the 
fact that although, so far as can be judged from the microscopic 
examination, the radiolarian shales are almost as rich in radiolarian 
remains as the black chert, the former contain only about 68 per 
cent. of silica, while the latter contains 91:06. This points, in our 
opinion, to the probability that the higher percentage of silica in 
the chert is due, not to the silica which it has received from the 
radiolarian tests, but rather to secondary silica derived from the 
siliceous tuffs. This supposition, however, is not proved, as, 
owing to the minuteness of the particles forming the base in 
which the radiolarian tests are embedded, it is almost impossible 
to determine whether that base was originally siliceous (formed 
perhaps of comminuted fragments of radiolaria) or partly aluminous. 
If, therefore, the cherts have been formed from the shales through 


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Vol. 55.] PALHOZOIC RADIOLARIAN ROCKS IN NEW SOUTH WALES. 33 


addition of the silica from the tuffs, it is evident that the silicifi- 
cation has been accompanied by a replacement of the bases. 

One of us (T. W. E. David) has already emphasized the fact that at 
the Jenolan Caves the black cherts, full of radiolarian casts, form a 
persistent selvage to the intrusive basic dykes of that neighbourhood.' 


VY. Microscopic CHARACTERS. 
(a) The Radiolarian Rocks. 


Slide No. 240 (1). Radiolarian limestone with tuff-fragments, 
Tamworth Common. A calcareous, dark bluish-grey rock weathering 
into a deep chocolate-brown pulverulent crust, with greenish patches 
about 12x 6mm. across. When etched with hydrochloric acid, the 
bulk of the rock is seen to be composed of insoluble material, some 
of which is silica. By reflected light the colour of this is pale 
citron-greenish-grey to very pale neutral tint or pale bluish-grey, 
resembling the opalescence of water with a few drops of milk in it. 

No primary quartz is present. The outlines of the particles are 
very irregular, with the exception of the radiolarian casts, which 
are spherical. 

The radiolarian tests mostly have their original substance pre- 
served, and are infilled with calcite. The medullary tests have 
suffered much less from decomposition than the cortical tests. 
These radiolaria are from 0°125 to 0-1 mm. in diameter. 

Slide No. 244 (2). A very homogeneous calcareous radiolarian 
rock, showing black dusty bands at intervals of about 3 to 6 mm. 
parallel to the planes of bedding (?). 

Under the microscope the black material is seen to belong to 
more or less perfect tests of radiolaria, the spaces between the 
meshes of the tests being filled in with translucent calcite. Most 
of the tests are so broken down as to have had almost all of their 
original structure obliterated, except their bare outline and the 
position of the largest of their spines. A few tests, however, are 
remarkably well preserved, but many are represented simply by 
translucent internal casts composed of calcite. In diameter these 
casts vary from about 0-1 to 0°15 mm. 

Slide No. 251 ().—Radiolarian limestone No. 5, Tamworth 
Common. Rock calcareous; a few fragments of a chiastolitic rock are 
present ; the fragments measure 0°5 mm. in diameter. The bulk of 
the rock is calcite, with a pale greenish mineral, weathered reddish- 
brown in places, and sometimes feebly dichroic and fibrous. This 
appears to have taken possession (in one case) of the interior of a 
radiolarian test. Small patches of chalcedonic quartz, forming casts 
of radiolaria, are scattered through the calcareous groundmass. It 
looks like an altered radiolarian rock, with chips of chiastolitic (?) 
claystone. 

Slide No. 563, Eth. (4789).—Tamworth, from clay-shales at the 
_ serpentine-quarry, about 30 chains north of Patterson’s house. 


Proce. Linn. Soc. N.S.W. ser. 2, vol, xi (1896) p, 565. 
W.J.G.8. No. 217, 7 D 


34 PROF. T. W. E. DAVID & MR. E. F. PITTMAN [Feb. 1899, 


An ochreous-brown soft rock containing radiolaria as casts and also 
with the test preserved. Some of these are translucent, others, 
occur as opaque ochreous casts in an ochreous base; while others 
have a distinct bluish-grey coloration. 

In size they vary from 0-083 to 031mm, Radiolaria are present 
at the rate of at least 50 to 60 in a field having a diameter of 
3°1mm. The particles composing the base are very fine-grained, 
about 0:05 to 0:063 mm. in diameter. 

Shde No. 623.—From a quarry west of the serpentine-dyke 
north of Patterson’s house, Tamworth. Rock somewhat similar to 
the preceding, but showing one very sharply- defined lamina of depo- 
sition 1 mm. thick, a dark grey layer with small radiolaria in the midst 
of a translucent yellowish-grey base crowded with radiolaria, mostly 
of larger size than those in the dark lamina. The greater number of 
the particles in the dark lamina are less than 0:025 mm. in diameter, 
Radiolaria are present at the rate of at least 100 in a field 3-1 mm. 
in diameter. Carbonaceous streaks and spots are scattered through- 
out the base. By transmitted light the radiolaria are either of a 
semi-opaque pale bluish-grey, or sub-translucent yellowish-grey. 
By reflected light the former appear opaque milk-white, and some 
of the latter ochreous. It may be noted that this rock is quite 
soft, and can be cut with a penknife despite the abundance of 
radiolaria in it, which are almost, if not quite, as numerous as 
those in the black cherts. | 

Slide No. 386 (9).—Tamworth Temporary Common. A eal- 
careous dark bluish-grey rock, with obscure casts of radiolaria. The 
base is chiefly calcareous, with numerous translucent bodies from 0:25 
to 0-5 mm. in length, and 0:05 to 0:025 mm. in width, showing a 
loose felted structure like the felspars in a basalt, though not so 
closely packed together. Most of these are calcareous, and some seem 
to be films filling irregular cracks in the groundmass. The base is 
stippled with brown dots and splashes due to limonite, probably 
pseudomorphous after pyrites. The whole rock, as regards structure, 
rather resembles a fine-grained basalt. 

Slide of black chert, Tamworth Common; taken from near 
radiolarian limestone No. 1. The base is very fine-grained and 
rather opaque, brownish-grey by reflected light, with numerous 
black streaks of carbon. Madiolaria are presént at the rate of 
about 100, more or less, in a field 3-1 mm. in diameter. They 
are preserved in chalcedonic quartz, and in a few cases an internal 
cast of the medullary test has been retained, showing as an opaque 
yellowish sphere surrounded by a wide zone of chalcedony, which 
in turn is enclosed by the broken-down remains of the cortical 
test. The base appears to be chiefly formed of the comminuted 
remains of radiolarian tests. 


(6) Tuff-rocks, ete. 


Slide No. 249 (A. 1).—The rock in this slide consists of a base 
chiefly made up of calcium carbonate, with numerous small fragments 


Vol. 55.] ON PALHOZOIC RADIOLARIAN ROCKS IN N.S. WALES. 35 


of felsitic rock and a few large angular fragments. The last- 
mentioned are from 19 to 25 mm. long, by about 1°5 mm. thick. 
They are respectively green and black radiolarian cherts. 

The matrix in which the fragments are embedded has the appear- 
ance of a dark bluish-grey to greenish-grey limestone, weathering 
superficially into a brown friable rock resembling Bath brick. It 
is chiefly formed of sub-translucent to opaque calcite, with small 
fragments of cryptocrystalline felsitic material containing small 
felspar-crystals about 0°36 mm. long by 0°125 mm. thick. (lt 
is improbable that the small crystals are chiastolite, as they show 
straight extinction.) The margins of these fragments are slightly 
more opaque than their inner portions. Pyrites is present in 
small crystals and crystalline aggregates, and so also are some 
dark streaks, apparently carbonaceous. In places there are patches 
of clear calcite, about 2°5 mm. in diameter, very much corroded 
at the edges, and shading off into the surrounding groundmass. 
A green mineral, feebly pleochroic, which seems of secondary 
origin, is associated with these patches of calcite, and also occurs 
interstitially in patches and streaks throughout the slide. It is of 
about the S&me hardness as serpentine. Small felspar-crystals 
measuring 0°5 mm. by 0°125 mm. are enclosed in some of these 
green patches. There are a few remains of indeterminable calcareous 
organisms present in the calcareous base. 

Slide No. 562, Hth. (4794).—The rock of this slide consists of 
alternating lamine of dark cherty claystone and tuff. The lamine 
are from 3°12 to 6°25 mm. thick. The tuff-rock is composed of 
angular corroded fragments of plagioclase and orthoclase, from 0:05 
to 0°36 mm. in diameter. Cryptocrystalline felsitic fragments are 
present, similar to those in slide No. 249 (p. 34), but not so con- 
spicuously developed. Quartz-grains with corroded edges are 
interspersed with the felspars, and measure from 0°25 to 0°36 mm. 
in diameter. The junction-line between the tuff and the radiolarian 
chert, in the case of the coarse-grained bands of tuff, is very sharp. 
In the case of the fine-grained tuff, the junction-line is less defined, 
and there are traces of a few felspar-crystals in the substance of 
the chert, but in close contiguity to the tuff. A little pyrites and 
a little magnetite are present in the tuff. The dark streaks in the 
chert are apparently carbonaceous. Several radiolaria may be 
recognized in the cherty claystone, represented by chalcedonic casts. 

Slide No. 611.—Agglomerate-matrix from Cleary’s Hill, near 
Tamworth. The base is a mixture of cryptocrystalline felsite, with 
phenocrysts of felspar, augite, and calcite, packed so closely together 
in it as to preclude the application of the term ‘ porphyritic’ 
to the structure of the rock. It has rather the appearance of an 
aggregate of much fractured and corroded macroscopic crystals, with 
interstitial felsitic material, and here and there small fragments 
of microcrystalline felsite almost blended at their margins with the 
base, and larger pebble-like lumps of the porphyritic andesite 
described in slide No. 621 (p. 36). 

A little pyrites and titaniferous iron (possibly some of this is 

D2 


36 PROF. T. W. E. DAVID & MR. E. F. PITTMAN [Feb. 1899, 


magnetite) are present. The felspars are chiefly plagioclase. A 
devitrified, spherical, yellowish glassy enclosure is present in the one 
quartz-grain visible in this slide. The augite is mostly granular or 
in angular fragments, and is pale greenish-grey to almost colourless. 
A yellowish-green decomposition-product, probably epidote, occurs 
interstitially and in minute veins. 

Slide No. 621.—Cut from an included rounded block or pebble 
of the Cleary’s Hill volcanic agglomerate. The rock is porphy- 
ritic, composed of -phenocrysts of plagioclase, some orthoclase, 
augite, and a few crystals of sphene: these are distributed through 
a rather opaque, whitish-grey, felsitic base. The phenocrysts are 
mostly idiomorphic, but a few have suffered somewhat from fracture 
and corrosion, though not nearly to the same extent as the pheno- 
crysts in the tuff proper surrounding the fragment. The phenocrysts 
are also fairly free from decomposition. ‘The sphene, which is 
idiomorphic, seems more pronounced in this section than in the 
22-yards tuff from Tamworth Common. One crystal of rather 
opaque calcite is visible. The rock may be described as an augite- 
diorite porphyry or porphyritic andesite. It appears to be closely 
allied to the tufts, but to be slightly more basic. 


VI. Conciustons. 


The following conclusions may be provisionally drawn from the 
observations recorded in this paper :— 


(1) That radiolaria were very important rock-forming organisms 
in the Paleozoic rocks of New South Wales, as (a) near 
Tamworth a thickness of strata exceeding 9000 feet, inclusive 
of submarine tuffs, is formed chiefly of tests of radiolaria; 
(6) these rocks extend for at least 85 miles northward 
to Bingara, and if the Jenolan Cave radiolarian rocks be 
on the same horizon, 200 miles southward, a total distance 
of at least 285 miles; (c) radiolaria are present in the bulk of 
these rocks at the rate of about one million to the cnbic inch. 

(2) That if the one bed of conglomerate observed near Tam- 
worth be not referable to the Radiolarian Series, as appears 
probable, the whole of the strata exposed are remarkably 
fine-grained, the fragments forming the base of the shales and 
cherts and red jaspers being not more than from 0-05 to 
0-025 mm. in diameter. 

(3) That the fact that a thick bed of coral-limestone and 
plant-beds, on three horizons, are interstratified with the 
Radiolarian Series, taken in conjunction with the previous 
conclusion, shows that the radiolaria were deposited in clear 
sea-water, which, though sufficiently far from land to be 
beyond the reach of any but the finest sediment, was 
nevertheless probably not of very considerable depth. 

(4) That the supposed absence of fossils from the Paleozoic 
sedimentary rocks over wide areas in the New England 


. Journ. Geol. Soc. Vol. LY, Pl. Il. 


Bar 


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151 152 153 


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Quart. Journ. Geol. Soc. Vol. LV, Pl. II. 


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(8577.28 olis— : ellis 
Cuitiny becinah raat i ess ibe Ns 
\NG 


Geological Sketch Map ea ae 5 in 
: == = Tina, Se 
2 AR s : = |_Menddbrea suas 


PARISH OF TAMWORTH 7 oe dtl 
COUNTY of INGLIS ginisesg etter 
EASTERN DIVISION N. S. W. Lies Ore 


° =@ on Section 


186 m.48/,Chs i 
Scale =H on Section - Pic J 
chainsO. 20 40 80 120 200 240 chaing RES fn 


oF ff 
Se ee a A gs Wollongong: 

i } . f) i ; 
miles Q) VW aT 1% o% 3 miles: te [pitiaicarrs Lake 


Recent & : M4 
Pleistocene(\kiii Alluvial Deposits a reiBoy 


Middle(?) fee iaalolariay cherts and claystones with thin bands of 
Devonian adiolarian limestone and very numerous beds of tuff 


Carbon Red hornblendic granite with sphene intruding into the 
a 


-iferous (?) adiolarian series 


memes Cuttings on the Great Northern Railway through Radiolarian shales & tuffs 


4 ty Note ibe eg Gon Gout the. 
The small arrows show the direction of dip localities where Radiolaria have 


been obseryed in New South Wales 


n the Palceozoic Rocks 
ht 152 1 It 


4% 


Quart. Journ. Geol. Soc. Vol. LY, Pl. III. 


: : ; Radiolarian Limestone 
‘ Radiolarian Limestone 3 to 4:Inches thick 
2 feet thick 


tone 
7 ft 


ustones with thi, 
Lepidodendrona 
essions of othe 


ana 
iferous Limestone 


ty claystones 


Travelling Stock 
x Route 


1000 feet above sea-level 


} ? 
CCURRENCE N AUSTRALE-BEDS. 


INDEX 
ey nu srone sare dark cherts with 
Radioluriagfthin bands of tuff 


CU Limestone 


Coral Limestone with Diphyphyllum 


a ae 


Quart. Journ. Geol. Soc. Vol. LY, Pl. III, 


Tamworth 
Temporary Common 


Radiolarian Limestone 


Radiolarian Limestone 3 to 4:Inches thick 


DEVONIAN : , ; 
Radiolarian Limestonein ; : z = s f " 
lenticular beds ,-—_-Radiolarian Limestone __ : Porteri Alveolites alveolaris,Heliolites, 
Fault,throws { DG jmcnesg SNES G to a He BS ea Stromatonurasirlngonores Cy stiehullin 2 feet thick 
SW, i ue | thick pe Af able Fault with throw to East 7 T © s 


[T4submarine tuffs 


CARBONIFEROUS RR] Granite 


Ww. 


7000 feet above sea-level 


Lydia 
u A 


n Stone 
A 


Radiolarian Limestone 
9 In 16 In.to 7 ft 


of perhaps 9000 feet 


guuty 1 


Tuff with abundant Fyiny \ , 
Lepidodendron masts Nace a Ss 
T Tit LT 11 --Claystones with thin beds of luff SS 
\ jul and Lepidodendron australe with SS H 
impressions of otherplant-remains x { 
es y 
= PGSt ee H Enlarged sketch 
Radiolarian Limestone 7 9" 4 09 
| lon can 
1 cale__, "Feet 
(@} i , , E 
1 Garnetiferous limestone = 
Y Claystones and tuffs c 18) oO tGarnetiferous Limestone 
F j \ 
examined, Probably chiefl y, MW  fiT 7, 58 
Y Not bably fly Wy Uy yy 1 |Cherty claystone Travelling Stock 
claystones and tuffs Wy, ty \ \\ hire Route 
/ MY, t xxx *K X 
Yj / VZZIN Ee Re Nae RUDE CREEK x 
7 AY / lays \ Kee K Xe Lae x x 
Scales yyy YY YN \ Aix Rk 8 OX er ee a Sa aera aii 
: i A Y ff, \ \ \ xx XxX x xx x 
Ut ' 16 32 Chains. Y yy HW YY Yuri XZx XK XARA MRK Re ye 
’ Horizontal-—— — Yi /14 / AMAA \\\\ NEES ir ean Tal Pe ax ee * x x x 
» Greate hE aes Sear hie 8 xx X x*x ®% 
800 7600 Feet. AS RR yg Ke Re Rw MRE ® 


Vertical = ae ye 


7000 feet above sea-level 


NEAR TAMWORTH (N.S.W.), 


SECTION 


SHOWING THE OccURRENCE oF THE Rapionartan Rocks, anp rHerk Reparion ro 148 Dryontan Corat-Limesronn AND to tHH LLEPIDODENDRON AUSTRALE-BEDS. 


SCTION 


1 A aie 


ate 4 Qik - 
DEY: 


« 


Wht 
/ ry A) 
TTI , Hi Hy ! 


SSNs 
PSEA 


NNSA 


SS 


- SSO 
LES SNS 


NS 


SS“ 


SSN 


| 
a 
ON S 


jets 
: 
ie i 
5 
. 
a2 AS ja 
r 
‘i 
# 
* ini 
” ee 
A a 
¥ 4 


dinfty \ Wa. Submarine Acidic Tuffs. 
iT [ah 


Devonian ° 5 6 
BM Radiolarian Shales and Mudstone 5 
( with some Cherts SPaE Finilht A 
Cc fli Mi i] 


785 Miles 64 chs. 


Gap of about 
713 che. about | 
Radiolarian Shales 


Alternating bands of Radiolarian 
Shales & tuffs 


Numerous Radiolarian Shale /nterlacing 
plant-impressions with plant-impressions Shales &tuffs 


= 


E.S.E. 


~ 


S 


Gap of about 29%chs. 
probably kadiolarian 
Shales 


186 Miles 49'Zchs. 


SSS 
SS 


SSS 


186 Miles 32 chs. 


Sa 


— 


= ~~~: 
SSS 


Horizontal Scalel inch= 30 yards 
80 0 


SS 


SECTION ON THE GREAT NORTHERN RAILWAY OF NEW SOUTH WALES, NEAR TAMWORTH, 


suowine Mippre (?) Deyonrin Raprouarian Snaves anp Supmarine Acipic Turrs. 


q 


Quart. Journ, Geol. Soc, Vol. LV, Pl. IV. 


re a a xe 
- 
a 
, ; ea 
» 
. i 
. 
» 
: 
; 
: 
3 
‘ 
‘ * 
- 
-_—- 


Oe yy oe *8 
SAN AEDS 
Sy kbet s 


Me 
es 


ay. 
; 
wy 
fe 
r 
pa 
i 
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" 
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3 
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r, 
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P 
* 
AS 
Bin 
cuit 
" 
So) 
Wat 
a 
4 
4 
ix 
tie 
_ 
i ea 
‘ 
By 18 Uae 
H 


Quart. Journ. Ceol. Soc. Vol. LY, Pl. Y. 


Mippze (?) Drvonsan Raprotarian Cxaystones, near Tamworru (N.S.W.). 


ee 
KS 
rd 
hs 
‘ 
¢ 
z 
+ 
ae 
if 
. 


Quart. Journ. Geol. Soc. Vol. LV, Pl. VI. 


LAMINATED AND Conrorrep RapioLARIAN CHERT IN SuBMARINE AcipIc Turr.—SEcTION ON THE 
Great Norruern Raitway, nEAR Tamworra (N.S.W.). 


re , 
+ Seah a " 4 ; ¢ nl é 
: a) sy i & Ne re y fi ater 
FM AND as ’ iy : ' _ 
‘ : 


+ y 
36 
a i 
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nde dy 
7 
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en i a R 
5 . 
“' ‘ ax 5) 
a vt "i 3 4 
Pas “ Me . 
Pains Went. nore 
An as ; 7 
L 4 by 
» Re x 5 , 
i ae ¢ 5 s 
‘i 3 Ais 
+ t . 
A , 
ae . 
is § “ 
eat - . 
a ; 4 : 
‘ vor » 
¥- 
os ‘ ‘ 
i as s 
4 
‘ a; es ! , 
ra 7 > ¥ " 
Y - . A ye? 
4 , x 
a . 5 
a 
? oa 
‘ 
{ ut r tte 
x 4 Pee ‘ ’ 
ye a. © = 
, = £ 
- § = 
‘ 7 a 
~ + ; 
x a . . , 
ie fF w+ ‘ = ‘ 
. a Det = “ 
Pe nic 
4 aw S F 
Ee o , : 
4 + 
Wi oer ft ne rie 
eee a = 
- z ¥ . 
" ? . nd ‘ ‘ % - 
. 4 « 
* wy ” ¥ 
4 vers ‘ . le 1 
Sie nae ney 
« y = A a 
* : a 
w 
+ . » f . 
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Bere I 4 dir 
: ~ a yee ‘whe 
: , 
y i 
, ‘ 
te 4 3 Ae - 2 
a ) f 
4 ‘ 
ty ee, 
“ ‘ z * 
. : 
> 


ee ees ee 


Quart. Journ. Geol. Soc. Vol. LV, Pl. VII, 


Raprowarian Cuerts, wirn SuBMARINE TUFFs CRUSHED INTO THEM.—QuARRY oN TamwortH Common (N.S.W.). 


° 
= 


y 1 a PA eS OP lag ( ne 
Dh) pe eee Ne ae eae 


Wols 55] ON PALHOZOIC RADIOLARIAN ROCKS IN N.S. WALES. 37 


District of New South Wales is now explained by the 
fact that they are almost wholly formed of marine micro- 
scopic organisms. 

(5) That the age of the rocks at Tamworth, judged from the 
macroscopic fossils, is probably either Middle or late De- 
vonian, or possibly even Lower Carboniferous. That the 
Barraba and Bingara radiolarian rocks of New South Wales 
are probably homotaxial, and that those of the Jenolan 
Caves may be somewhat older, perhaps Lower Devonian or 
Upper Silurian. 


Our thanks are especially due to Mr. Donald A. Porter, of Tam- 
worth, for much information regarding the geology of Tamworth, as 
well as for personal help and guidance; to Mr. G. W. Card, F.G.S., 
for petrological observations; and to Mr. W. 8S. Dun, Assistant 
Librarian and Paleontologist to the Geological Survey of New South 
Wales, for references to literature relating to the radiolaria. 


EXPLANATION OF PUATES JI-VII. 


Puate IT. 


Geological sketch-map of the parish of Tamworth (N.S.W.), on the scale of 
1 inch to the mile; with a key-map showing part of the Colony of New South 
Wales. 


Puate Iil. 


Section near Tamworth (N.S.W.). Showing the oceurrence of the radio- 
larian rocks and their relation to the Devonian coral-limestone and to the 
Lepidodendron australe-beds. 


PuaTeE LY. 

Section of submarine acidic tuffs and radiolarian shales of Middle (?) Devonian 
age, exposed in cuttings on the Great Northern Railway, near Tamworth 
(N.S.W.). Section approximately from west-north-west to east-south-east. 

Puate V. 


Radiolarian claystones, near Tamworth (N.S.W.), dipping west 20° south 
at 52°. Probably Middle Devonian. 


Puate VI. 


Laminated and contorted radiolarian chert in submarine acidic tuff, Section 
on the Great Northern Railway, near Tamworth (N.S.W.). 


Puate VII. 


Radiolarian cherts, with submarine tuffs crushed into them. Quarry on 
Tamworth Common (N.S.W.). 


[For Discussion, see p. 64. ] 


38 DR. G. J. HINDE ON THE RADIOLARIA INTHE  [Feb. 1899, 


4, On the Raptiorartia in the Devonian Rocks of New Sourn Wates. 
By Grorce Jennines Hinpz, Ph.D., F.R.S., F.G.S. (Read 
November 9th, 1898.) 


[Puarzs VIII & IX.] 
ConTENTS. 


TD. Dtroduction wcscpiencectesincicet stweneenueveewenciencinaatlnte Cheer ets dee weeE eeteee 38 
II, Character of the Rocks and Mode of Preservation of the Radiolaria. 38 
(a) The Chert-rocks with Radiolaria. 
(6) The Siliceous Limestones with Radiolaria. 
(c) The Siliceous Claystones and Shales with Radiolaria. 
(d) The Volcanic Tuffs with Radiolaria. 


a12 Description of the Radiolaria, .22f5.04 A015. nota Pacis eee eee 42 
IV. General Characters and Affinities of the Radiolaria .............se00- 58 

V. Fossils associated with the Radiolaria  ...........-ceccecsccccececscceences 60 
WL, SAAR Fe cictoe se. wats esti acticmjommivicanins at's a's ojctade@c seaman Sane ee er 61 


I. IntTRODUCTION. 


On the invitation of the authors of the foregoing paper, I very 
willingly consented to undertake an examination and description of 
the radiolaria occurring in the extensive series of Devonian rocks 
in New South Wales which they have recently brought to light, and 
accordingly they forwarded to me, in the spring of 1897, a box of 
hand-specimens of typical examples of the different kinds of radio- 
larian rocks, and these have been supplemented since by a few 
other specimens received during the present year. Microscopic 
sections have been prepared from them ; and from such as contained 
the radiolaria in good preservation (as, for example, the dark 
siliceous limestones and some of the volcanic tuffs from Tamworth), 
numerous slides were made, so as to obtain as large a variety of the 
organisms as possible. 

The rocks sent me were derived from the following four locali- 
ties :—(1) Bingara and (2) Barraba: red jaspery cherts ; (3) Jenolan 
Caves and vicinity: black chert; (4) Tamworth: black chert, dark 
siliceous limestone, siliceous claystone or shale, and volcanic tuff. 


TI. CHaracter oF tHE Rocks anp Mops or PRESERVATION OF 
THE RADIOLARIA. 


Before describing the radiolaria, it will be desirable to refer to 
the character of the rocks of which they form so important a part, 
and to their mode and condition of preservation. 


(a) The Chert-rocks with Radiolaria. 


The jaspery cherts of Bingara and Barraba are hard and flinty, 
of a brick-red tint, and fairly translucent in section. They are 
traversed in all directions by thin microscopic veins and strings of 
microcrystalline quartz. The rock is cryptocrystalline ; only a few 


Vol. 55.] DEVONIAN ROCKS OF NEW SOUTH WALES. 39 


casts of radiolaria can be distinguished in it; these are extremely 
shadowy and indistinct, and can scarcely be differentiated from the 
groundmass. I can see no evidence of metamorphism in the rock ; 
it closely resembles some jaspery radiolarian cherts from the Culm 
of Devon, and also some, of presumed Jurassic age, from California, 
in which there is no question of contact-alteration. The samples 
examined were :—No. 575, from Lower Bingara, and No. 573, 
from Oakey Creek. 

In only one of the chert-specimens from the Jenolan Cave district 
(No. 569, McKeown’s Creek) have I been able to recognize radio- 
laria. This rock is a black chert traversed by a close network of 
microscopic quartz-veins. The radiolaria are fairly abundant ; they 
are in the condition of casts of microcrystalline silica, without 
structure, and neither spines nor central tests are shown. The 
rock is a radiolarian chert without indications of metamorphism. 

The other specimens (Nos. 568, 570) from the same locality as 
the above are black, opaque, impure cherts, in which no organisms 
could be seen, and the same may be said of a specimen from Cave 
Creek (No. 571) in which there is an admixture of fragments of 
tuff. 

At Tamworth the chert associated with the dark siliceous lime- 
stones is a hard, black, compact rock, very finely laminated, as shown 
by lines of lighter and darker materials in the microscopic sections. 
The matrix is filled with dark, minutely granular, or flocculent 
material, considered as carbonaceous by Messrs. David & Pittman ; 
but some of it may possibly be ferruginous. This dark substance is 
either generally dispersed throughout the rock, or occurs in denser 
patches and streaks. In thin section under the microscope the 
rock is seen to be crowded with radiolaria, which appear as small, 
clear spots, for the most part circular in outline, without definite 
bounding-walls. Neither spines nor central tests are shown in the 
great majority of the forms. The radiolarian casts are usually 
infilled with cryptocrystalline silica, sometimes with fibrous chalce- 
donic silica, and in exceptional instances with crystalline quartz. 

The radiolaria preserved in this dark chert are distinguished 
from those in the intervening beds of dark siliceous limestone by the 
absence of the latticed structure of the cortical test, and the nearly 
complete disappearance of the radial spines and medullary test. It 
can hardly be doubted that the chert furms were originally of a 
similar character to those in the limestone interbedded with the chert, 
and that their present differences arise from the different conditions 
of fossilization in the chert and limestone respectively. Judging 
only from their present appearance, the simple, spineless forms in 1 the 
chert would be referred to groups quite distinct from those in the 
dark limestone, with which, there is good reason to believe, they 
were originally identical. 

In one specimen from Tamworth (No. 375, 4-5) a nodule of the 
black chert is enclosed in a bed of tuff. The chert appears to be 


' The numbers affixed to the specimens throughout this paper are those used 
by Messrs. David & Pittman. 


40 DR. G. J. HINDE ON THE RADIOLARIA INTHE ([Feb. 1899, 


but very slightly, if at all, altered; the casts of radiolaria are 
similar to those in the chert described above, and the groundmass 
has less of the dark carbonaceous(?) material and a somewhat 
larger number of very minute polarizing particles. 

In general characters the radiolarian chert from these Australian 
localities very closely resembles that from Mesozoic and Paleozoic 
formations in other parts of the world. The radiolaria in it are too 
poorly preserved for either generic or specific determination ; one 
can only say that the rock is filled with their casts, and that the 
silica of the chert has most probably been derived from their tests. 


(b) The Siliceous Limestones with Radiolaria. 


The examples of this rock which I have examined are all from 
Tamworth, and they bear the following numbers :—245 3, 247 3-4, 
248 4, 2568, 4-4 a. The rocks are dark to a dull black, fine- 
grained, compact, homogeneous. They weather on the outer 
surface to a porous brown crust, having much the appearance of 
rottenstone. In only one instance (248 4) is the rock traversed by 
minute veins, and these are partly filled with calcite and partly 
with microcrystalline silica. The rock readily effervesces in acid, 
and leaves a brown residue in which there may be seen fairly perfect 
radiolaria in whitish silica, with spines and central tests. Rarely, 
however, are the organisms completely freed from the porous brown 
matrix, and they are altogether too fragile to be manipulated for 
examination, so that for this recourse must be had to microscopic 
sections, 

In thin microscopic sections of this dark limestone, made in the 
usual manner, the radiolaria are very imperfectly shown; as a 
rule, only the outlines of circular and oval forms, without spines, 
are visible, and the tests and the interspaces of the groundmass are 
filled with somewhat dirty-looking calcite. On removing, however, 
the calcite by etching the thin section in position on the glass slide 
with dilute acetic acid for a short time, and after gently washing it 
and covering it cautiously with balsam and thin glass, the radiolaria 
are shown with remarkable distinctness. In many of the tests, which 
range between 0:06 and 0:2 mm. in diameter, the radial spines and 
the inner or medullary tests are perfectly preserved ; in these latter, 
as a rule, the delicate latticed structures are shown more clearly 
than in the outer or cortical tests. The tests and spines are, not 
infrequently, as transparent as in recent or Tertiary forms, and, 
like these, they retain the original amorphous condition of the silica. 
But more generally the original tests are now replaced by a dark 
substance, as if some compound of iron had united with the silica. 
Also many of the radiolaria are now represented only by hollow 
casts, their tests having been dissolved. 

In the best preserved of the etched sections, the rock—minus the 
calcite—appears to be wholly composed of the tests of radiolaria, 
crowded together and embedded in a confused mass of broken spines 
and fragments of lattice-work, the débris of forms which have gone 


Vol. 55.] DEVONIAN ROCKS OF NEW SOUTH WALES. 41 


to pieces when the radiolaria were being deposited at the sea- 
bottom. | 

In polarized light between crossed nicols, the etched sections for 
the most part remain dark, but occasionally the faint outlines of 
radiolaria in cryptocrystalline silica are visible, and also minute 
polarizing particles of uncertain character. Microscopic cubes of 
pyrites are not at all uncommon in the dark limestones, but I have 
not observed any clastic inorganic fragments. 

The calcareous constituent of this radiolarian siliceous limestone 
appears to be wholly in the form of crystalline calcite, and there are 
no indications in the specimens examined of foraminifera or other 
calcareous organisms which could have furnished the calcite. It is 
possible that originally they may have been in the rock and subse- 
quently obliterated, for in the coral-limestones which occur in part 
of the Tamworth series (258 B) the coral-structure is now replaced 
by calcite. However this may be, it seems clear that this siliceous 
limestone must have been originally a radiolarian ooze, and that the 
calcite which now infills the tests and interspaces of the organisms 
was subsequently introduced, giving solidity and density to the 
light, porous, siliceous aggregate. The rock when treated with acid 
remains of the same volume after the lime has been removed, and 
the porous residue, as we have seen, essentially consists of the 
siliceous remains of radiolaria. 

From the etched sections of this rock about half the forms described 
and figured in the following pages were obtained. 


(c) The Siliceous Claystones and Shales with Radiolaria. 


The only specimens of this description of radiolarian rock that I 
have examined are from Tamworth (590, 62525), where Messrs. 
David & Pittman’ have ascertained that it is some thousands of 
feet in thickness. The rock is greyish-brown, somewhat lighter- 
- tinted on the outer surface, compact, jointed, and traversed in 
places by narrow quartz-veins. It gives no reaction in acid. The 
weathered surface of the rock is covered with minute grey specks, 
barely visible to the naked eye; these with a lens are seen to be 
radiolaria, partially weathered out from the brownish matrix. 
In some instances the lattice-structure, and more frequently the 
radial spines of the organisms are preserved in position. A thin 
section of the rock under the microscope shows a translucent ground- 
mass of very minute, brownish, polarizing particles. The rock is 
crowded with radiolaria, which, however, in the section show 
neither structure nor spines; they are now infilled with a brownish 
material (whitish-grey by reflected light) of an uncertain character. 

As the authors of the foregoing paper remark, this claystone and 
shale apparently contain as many radiolaria as the black chert, 
while the chemical analysis shows a distinctly smaller proportion of 


1 These authors state that the claystones at Bingara and Barraba are litho- 
logically similar to those exposed at Tamworth. 


42 DR. G. J, HINDE ON THE RADIOLARIA INTHE  [Feb. 1899, 


silica in the rock. This seems to be accounted for by the greater 
quantity of very fine clay or silicate of alumina that has taken the 
place of the silica. The radiolaria in the rock, judging from the 
weathered-out forms, are fairly well preserved, but in the micro- 
scopic sections they are obscured by the aluminous groundmass, 
which cannot be eliminated as in the case of the calcium carbonate in 
the siliceous limestones. Hence their generic and specific characters 
cannot be determined with precision, but there is no reason to doubt 
their similarity to the forms in the intervening siliceous limestones. 


(d) The Volcanic Tuffs with Radiolaria. 


Some of the beds at Tamworth associated with the radiolarian 
siliceous limestones and claystones appear to be made up mainly of 
volcanic detritus, judging from the characters shown in microscopic 
sections. The specimens examined bear the numbers 240 1, 2432, 
249 a1, 257 a, 380 p-n, and 387 p. The rocks are mostly of a bluish 
tint ; they may be scratched with a penknife, and readily effervesce in 
acid. The outer surface weathers to a rusty brownish crust of fine 
and coarse granular materials. Under the microscope the rock is 
seen to consist of irregular fragments of tuff, lapilli, and ash of 
different degrees of fineness; in a coarse example the fragments 
range up to 2°5 mm. in diameter. Some fragments are vesicular, 
and the vesicles are regularly oval and often filled with a greenish 
mineral. As they are of about the same size as radiolarian casts, they 
might easily be mistaken for these organisms. The base or ground- 
mass of the tuff-rock is calcite, which cements the fragments together. 
Scattered sparsely between the tuff-fragments and, like them, 
embedded in the calcitic base there are a few radiolaria, which 
can hardly be seen until the calcite has been removed by acid, in the 
same way as in the radiolarian limestones. The forms in the tuff- 
rocks are generally well preserved ; the lattice-structure of the outer 
and inner tests and the radial spines can be distinguished, and they 
still retain the colloid silica of the test. In exceptional instances 
the interior of the test has been infilled with colloid silica, but more 
usually with calcite. Owing to their isolated occurrence, the syste- 
matic characters of these tuff radiolaria can be better ascertained 
than in the forms in the limestones, and a majority of those described 
and figured in the following pages are from a single hand-specimen 
of tuff (887 D), in which the fragments are coarser than the 
average. 


Ill. Description oF THE RADIOLARIA. 


The descriptions and figures which follow have in all cases been 
taken from the radiolaria seen by transmitted light, in the etched 
microscopic sections of the dark siliceous limestones and the volcanic 
tuffs of the Tamworth series. It has not been found practicable 
to figure the forms weathered out on the surface of the rocks, or 
partially set free by acid. In the etched sections the outer cortical 


Vol. 55. ] DEVONIAN ROCKS OF NEW SOUTH WALES, 43 


tests of the radiolaria are less frequently shown than the inner 
or medullary tests. The forms in the tuff are best preserved ; 
those in the limestones are usually so thickly mingled together 
that their characters are often hidden, while the chert forms, being 
casts merely without structure, are of no use for systematic de- 
scription. The classification of Haeckel, as given in his Challenger 
Report on the Radiolaria,! has been followed. 

The measurements given are in millimetres and decimal parts, 
and the figures in the plates are all drawn to the same scale of 
200 diameters. As the radiolaria are all from Tamworth and 
belong to the same series of Devonian rocks, the locality and 
formation are not repeated with each species, and only the numbers 
of the beds are given. The slides containing the figured specimens 
are in my own collection. 


Clas RADIOLARIA, Miller. 
Subclass SPUMELLARIA, Ehrenberg. 
Order BELOIDEA, Haeckel. 


Genus SpH#RozouM, Meyen. 


The skeleton consists of free siliceous spicular bodies of various 
forms. 


SpHzRozoum sp. (Pl. VIII, figs. 1 a—-1e.) 


The only spicules of this genus which have been observed are very 
minute, apparently three-rayed forms; the rays are short and have 
either rounded or truncate terminations, or they are club-shaped. 
They range between 0°03 and 0:04 mm. in diameter. They have the 
same glistening appearance as that already noticed in these spicules 
from other deposits. They occur detached and very sparingly, both 
in the dark siliceous limestones and in the volcanic tuffs. Nos. 4, 
245 3, 3887p. Similar forms have been found in nearly all radio- 
larian rocks from the Cretaceous downwards. 


Order SPH ZROIDEA, Haeckel. 


Genus CenospH#@RA, Ehrenberg. 
The test is a simple latticed sphere, without radial spines. 


CENOSPH#RA SCITULA, sp. nov. (Pl. VIII, fig. 2.) 


Test small, with delicate narrow lattice-bars ; the pores are some- 
what subangular and unequal; in the angles are very minute 
spines. Diameter of test, 0°09 mm.; of the pores,0-01 mm. Rare. 
In siliceous limestone. No. 2453. This form corresponds in size 
with C. minuta, Pantanelli, but according to Dr. Riist? the pores 
in this latter are only about half the size of those in C. scetula. 


1 Zoology, vol. xviii (1887). 
? Palzontographica, vol. xxxiv (1888) p. 190. 


44 DR. G. J. HINDE ON THE RADIOLARIA INTHE  [Feb. 1899, 


CrnosPHERA AFFINIS, Sp. nov. (Pl. VIII, fig. 3.) 


This form corresponds in size with the preceding, but the pores 
are more regular and nearly circular, and the surface-spines are 
more prominent. Diameter of test, 0°l to 0°13 mm.; of the pores, 
0-015 mm.; length of spines, 0:03 mm. In the siliceous limestones 
and in the volcanic tuff. Nos. 245 3, 387 p. 


Genus LiospH#RA, Haeckel. 


The test consists of two concentric latticed spheres, both extra- 
capsular. 


Liospomra(?) sp.ind. (Pl. VIII, fig. 4.) 


The specimen is only shown in section, and the pores are not 
distinguishable; the inner sphere is connected with the outer by 
numerous rods, which extend as small spines beyond the surface 
of the outer test. ‘The lower portion of a stouter spine is also 
present. Diameter of the outer sphere, 0°145 mm.; of the inner, 
0-09 mm. Rare. In siliceous limestone. No. 2453. 


Genus RuopospH@RA, Haeckel. 


The test is composed of three concentric spheres, one medullary 
and two cortical. 


ReopospHzRA Russti, sp.nov. (Pl. VII, fig. 5.) 


The cortical tests are only shown in section, and the outer one is 
but imperfectly preserved. Numerous rods or spokes connect the 
medullary with the cortical spheres, and some of these are extended 
into short spines. The medullary test has nearly circular pores, and 
there are indications of rods radiating from its centre. Diameter 
of outer test, 0°155 mm.; of the inner cortical, 0:13 mm.; and of the 
medullary, O-l mm. Rare. Found in dark siliceous limestone. 
No. 2453, The species is named in honour of Dr. H. Rust, of 
Hanover. 


Genus SponeopLeama, Haeckel. 


An outer cortical sphere of spongy framework, enclosing in the 
centre a single latticed sphere. 


SPONGOPLEGMA AUSTRALE, sp. nov. (Pl. VIII, fig. 6.) 


The cortical test consists of a minutely porous mesh, and the 
exterior surface is somewhat rough. ‘The medullary test is smooth, 
delicate, and with minute, somewhat subangular, pores ; it is con- 
nected with the porous test by numerous slender rods. Within the 
medullary test there are several very small, free, spicular bodies, 
having three or four rays, not unlike Spherozoum-spicules, but of 
a more slender character. Diameter, 0°12 mm.; thickness of spongy 
sphere, 0:02 mm.; diameter of the medullary test, 0°065 mm. Rare. 
Found in volcanic tuff. No. 387. 


Vol. 55. ] DEVONIAN ROCKS OF NEW SOUTH WALES. 45 


Genus DoryspH ZRA, Hinde. 


The test is a simple latticed sphere, with a single radial spine. 
Secondary smaller spines are also occasionally present. 


DorysPH=RA ECHINATA, Sp. noy. (Pl. VIII, fig. 7.) 


Test thin, the lattice-pores rounded or polygonal, unequal in size ; 
the radial spine now slender and styliform, probably much stouter 
originally ; the surface of the test is also covered with numerous 
minute secondary spines. Diameter of test, 0°1 mm.; width of larger 
pores, 0°01 mm. ; length of radial spine,0°1 mm. In siliceous lime- 
stone. No. 2453, This species differs from those of the same 
genus in the Ordovician chert of Scotland by its smaller size and | 
the secondary spines ;* while its size and irregular pores also dis- 
tinguish it from Dorysphera (Monostylus) hirsuta (Cayeux).” 


Genus X1PpHOSPH#RA, Haeckel. 


The test is a simple latticed sphere, with two free radial spines 
in the same axis. 


XIPHOSPH#HRA MINAX, sp. nov. (PI. VIII, fig. 8.) 


The test is relatively thick, the lattice-pores and bars are small 
and about equal in width, the spines long, stout, and with a central 
keel. They are now unequal in length, but this probably arises 
from their imperfect preservation. Diameter of test, 0-127 mm. ; 
thickness, 0°02 mm.; width of pores, about 0°007 mm.; length of 
longest spine, 0-3 mm., and thickness at base,0°045 mm. In siliceous 
limestone. No. 2453, This form approaches near to X. macrostyla, 
Rist, from the Upper Devonian of the Harz,’ but the pores are 
smaller and the spines longer. 


Genus StyLospuH RA, Ehrenberg. 


The test consists of two concentric latticed spheres, with two 
opposite radial spines. 


SryLosPH#RA opTusa, sp. nov. (Pl. VIII, fig. 9.) 


The cortical test has a thin wall and smooth surface. The lattice- 
pores are wider than the bars between them. The medullary sphere 
is only faintly shown; the pores in it are small and delicate. This 
inner test is connected with the outer by the basal portion of the 
spines, which are stout, keeled, gradually tapering and obtusely 
pointed. Diameter of test, 0-115 mm. ; thickness of wall, 0-01 mm.; 
width of pores, 0°0075 mm.; diameter of inner sphere, 0045 mm. ; 
length of spines, 0°22 mm., and thickness at base, 0°045 mm. 
In volcanic tuff. No. 387 p. 


1 Ann. & Mag. Nat. Hist. ser. 6, vol. vi (1890) pp. 52-53 & pls. iii & iy. 
2 ‘Etude microgr. des Terr. sédiment.’ 1897, p. 189 & pl. vii, fig. 12. 
3 Palzontographica, vol. xxxviii (1892) p. 141 & pl. ix, fig. 10. 


46 DR. &. J, HINDE ON THE RADIOLARIA INTHE [Feb, 1899, 


STYLOSPHZRA VETUSTA, sp. nov. (Pl. VIII, fig. 10.) 


The cortical sphere is only shown in section ; the wall is thin, and 
the pores are small; the medullary sphere is smooth, with delicate 
somewhat subangular pores. The spines very gradually taper. 
Diameter of cortical test, 0°11 mm.; of medullary test, 0-04 mm. ; 
length of spines, 0°105 mm., and shalieees at base, 0° 02mm. In 
volcanic tuff. No. 387. 


Genus STAUROSPH#RA, Haeckel. 


The test is a simple latticed sphere, with four equal radial spines 
disposed crosswise. 


STAUROSPHZERA (?) ORNATA, sp. nov. (Pl. VIII, fig. 11.) 


Surface of the test smooth, wall moderately thick, pores rounded, 
unequal, the lattice-bars about half the width of the pores. Only 
one of the four spines is now intact; this is tapering, keeled, and 
has, at its extremity, four minute rays or spines diverging at 
right angles. Of the other spines, two are only indicated by short 
stumps, and the termination of the fourth is concealed. Diameter 
of test, 0-095 mm. ; thickness, 0:01 mm. ; length of spine, 0°12 mm., 
and thickness at base, 0°022 mm. In volcanic tuff. No. 387. 


STAUROSPH HRA PUSILLA, sp. noy. (Pl. VIII, fig. 12.) 


Test small, wall thin, with irregular, large and small, subangular 
pores and slender lattice-bars; the radial spines are short, keeled, 
and acutely pointed. Only three are shown, the place of the fourth 
being concealed by matrix. ‘The interior of the test has six or more 
slender rods radiating from the ends of a short central bar of the 
same character as those in the genus Stigmosphera, Haeckel. 
Diameter of test, 0-065 mm.; width of largest pores, 0:015 mm. ; 
length of spine, 0°04 mm., and thickness at base, 0°02 mm. Rare. 
Found in volcanic tuff. No. 387p 


Genus StavrotoncHeE, Haeckel. 


The test consists of two concentric latticed spheres, with four 
simple, equal, radial spines disposed crosswise. 


SravrotoncHeE Davivt, sp. nov. (PI. VIII, fig. 13.) 


The cortical test has numerous small surface-spines and circular 
pores. ‘The radial spines are stout, keeled, and terminate obtusely. 
The inner sphere has minute rounded pores. Diameter of test, 
0-11 mm.; of the medullary sphere, 0°05 mm.; length of spines, 
0-15 mm., and thickness at base, 0°035 mm. This form appears to 
be very common in the dark siliceous limestones of Tamworth, but as 
a rule the spines are seldom preserved intact, and in the specimen 
figured only one is complete. Some of the forms figured by 
Prof.T. W. E. David! probably belong to this species. 


1 Proc. Linn. Soc. N.S.W. ser. 2, vol. xi (1896) pl. xxxviii, figs. 1, 4 & 8. 


Vols 5.) DEVONIAN ROCKS OF NEW SOUTH WALES. AT 


STAUROLONCHE TENELLA, sp. nov. (Pl. VIII, fig. 14.) 


The cortical test is only shown in section; the wall is slender, 
with rounded pores; the inner sphere is very delicate, and the pores 
are circular. The spines are keeled and slightly longer than the dia- 
meter of the test. Diameter, 0:09 mm.; of inner sphere, 0°04 mm. ; 
leneth of spines, 0-11 mm., and width at base, 0°022 mm. In 
siliceous limestone. No. 2453. 


STAUROLONCHE LATERNA, sp. nov. (PI. VIII, fig. 15.) 


The cortical test is only shown in section; the wall is moderately 
thick and minutely spined; the medullary test is somewhat octa- 
hedral in form; the pores are subangular, and very unequal in 
size. The spines are keeled or prismatic in section; their axes are 
not at right angles to each other. Diameter of the outer test, 
0-095 mm.; of the inner, 0°04 mm.; length of spine (beyond the 
test), 0-07 mm., and width at base, 0°015 mm. In volcanic tuff. 
No. 387 v. The structure of the medullary test readily characterizes 
this species. 


SrAUROLONCHE sciTuLa, sp. nov. (PI. VIII, fig. 16.) 


Cortical test with thick walls and small pores; the medullary 
sphere is very delicate, and the pores are subangular. Only two 
of the radial spines are preserved; they are slender, apparently 
circular in section, and very gradually taper to a point. Secondary 
surface-spines are also present. Diameter of test, 0-1 mm.; of the 
inner sphere, 0°042 mm.; length of spines, 0°11 mm., and thick- 
ness, 0°005 mm. Rare. Occurs in volcanic tuff. No. 387. 


Genus STAvUROLONCHIDIUM, Haeckel. 


Test of two concentric latticed spheres, with four radial spines in 
two different pairs. 


STAUROLONCHIDIUM OBLIQUUM, sp. nov. (PI. VIII, fig. 17.) 


The cortical test is thin, with small circular pores and surface- 
spines; the medullary test delicate, with polygonal pores. The 
spines are keeled ; those forming the transverse axis are imperfect, 
but they appear smaller than those of the vertical axis. Diameter 
of cortical test, 0-11 mm.; of medullary test, 0°06 mm.; width of 
pores, 0:009 mm.; length of vertical spine, 0°21 mm., and width at 
base, 0°035 mm. In siliceous limestone. No. 2453. 


Genus TRILoNcHE,! gen. nov. 


The test consists of two concentric latticed spheres, with three 
radial spines at equal or unequal distances apart. Secondary surface- 
spines are also sometimes present. The forms included in this 
genus are very numerous in the Tamworth radiolarian rocks. 


* Tpets Adyxar: three spears. 


48 DR. G. J. HINDE ON THE RADIOLARIA IN THE _[ Feb. 1899, 


TRILONCHE VETUSTA, Sp. nov. (Pl. VIII, fig. 18.) 

The cortical test, as seen in section, is thin, with small lattice- 
pores and surface-spines ; the inner test has minute circular pores 
enclosed by a polygonal framework ; the radial spines are moderately 
stout, keeled or prismatic, subequal in length, and at unequal distances 
apart: they appear to be in the same plane. The proximal end of 
the spines is stout, and connects the medullary with the cortical 
sphere. Diameter of outer test,0°095 mm.; of inner test,0°045 mm. ; 
length of spines, 0°09 mm., and thickness at base, 0°025 mm. In 
volcanic tuff. No. 387. 


TRILONCHE VETUSTA, var.a. (Pl. VIII, fig. 19.) 

This form is very similar to the preceding, but the surface 
appears to be smooth and the pores of the test somewhat finer. In 
addition to the three normal spines, which are unequal in length 
and in their distance apart, there is a small supernumerary radial 
spine. Diameter of cortical test, 0-1 mm.; of medullary test, 0-042 
mm.; length of spines, 0°06 to 0:09 mm., and thickness at base, 
0:025 mm. In volcanic tuff. No. 387p. 


TrinoncHE Pirrmani, sp. nov. (Pl. VIII, figs. 20 & 21.) 


Cortical test with small pores; medullary test very delicate; 
pores circular; radial spines stout, keeled, unequal in length, and 
at nearly equal distances from each other. Of the two specimens 
figured, fig. 20 measures 0°15 mm. in diameter, the medullary test 
being 0:055 mm. in diameter, the spines 0°19 to 0°26 mm. iong, 
and 0:035 mm. thick. In fig. 21 the cortical test is 0-115 mm. 
in diameter; the medullary test has not been preserved; the 
spines are 0-1 to 0-15 mm. long, and 0:035 mm. thick. The 
figured specimens are from volcanic tuff, No. 387); similar forms 
are also common in the dark siliceous limestones of the Temporary 
Common, Tamworth. No. 2453. 


TRILONCHE ELEGANS, sp. nov. (Pl. VIII, fig. 22.) 

The cortical test is only shown in section; the wall is thin, with 
small pores; the medullary test is about half the diameter of the 
cortical; the pores are subcircular, with a delicate polygonal frame- 
work. The radial spines are short, conical, nearly equal in length, 
but at unequal distances apart. Diameter of test, 0°09 mm.; of 
inner sphere, 0°047 mm.; length of radial spines, 0‘04 mm. In 
siliceous limestone. No. 2453. 


Genus ACANTHOSPHZHRA, Ehrenberg. 
The test is a simple latticed sphere, with eight or more radial 
spines of the same kind. 


ACANTHOSPHZRA AUSTRALIS, sp. nov. (PI. VIII, fig. 23.) 


Only sections of this form are shown ; the spines are short, robust, 
conical, and somewhat unequal in length, but of the same kind; 


Vol. 55.] DEVONIAN ROCKS OF NEW SOUTH WALES. 49 


there are nine exposed in the section; the pores are about as wide 
again as the lattice-bars between them. There are indications of 
siliceous rods, like those of Stigmosphera, within the test. Diameter 
of test, 0°135 mm.; thickness of wall, 0°01 mm.; width of pores, 
0-01 mm.; length of spines, 0-02 to 0°06 mm., and thickness at base, 
0-015 to 0:02 mm. Rare. In volcanic tuff. No. 387 p. 


AcCANTHOSPH#RA ETHERIDGEI, sp. nov. (Pl. VIII, fig. 24.) 


Test small, with delicate lattice-frame and circular pores; the spines 
are slender and elongate: nine are shown in the specimen. In 
the interior of the test there are six rods, three radiating from each 
end of a small central bar; they extend to the surface of the test, 
and apparently connect with the radial spines. Diameter of test, 
0-085 mm.; width of pores, 0°01 mm. ; longest spine, 0°14 by 0-01 
mm. at the base. In volcanic tuff. This species is closely related to 
A, laxa, Hinde & Fox, from the Culm of Devon,’ but it is considerably 
smaller. It is named in honour of Mr. Robert Etheridge, jun., of 
the Australian Museum, Sydney. 


Genus HetiosPpH=RA, Haeckel. 


The test is a simple latticed sphere, with large radial and inter- 
mediate smaller secondary spines. 


HeELIosPH@RA RoBuSTA, sp. nov. (Pl. VILI, fig. 25.) 


The test, as seen in section, has thick walls, with pores about 
half as wide again as the lattice-bars ; six primary radial spines, 
of varying length, are shown: they are prismatic in section. The 
secondary spines are very minute,and they seem to be present on each 
node of themesh. Portions of siliceous rods are seen within the test. 
Diameter of test, 0°14 mm. ; thickness, 0-015 mm.; width of pores, 
0-01 mm. ; length of spines, 0:025 to 0-1 mm., and thickness at base, 
0-02 to 0°03 mm. Rare. Occurs in volcanic tuff. No. 387 pd. 


HetiospHzRs TamMworruy, sp. nov. (PI. VIII, fig. 26.) 


The pores in the test are slightly wider than the lattice-bars ; the 
larger radial spines are conical, and evenly tapering: nine of them 
are shown in the section; the secondary spines differ only in size 
from the larger. Diameter of test, 0°14 mm.; thickness, 0-01 mm. ; 
length of primary spines, 0°06 to 0-1 mm.; thickness at base, 
0°02 mm. Differs from the preceding in its thinner walls, more 
tapering primary and larger secondary spines. In siliceous lime- 
stone. No. 2453. 


HELIOSPHZRA FENESTRATA, sp.nov. (Pl. VIII, fig. 27.) 


The test has rounded and oval pores of different sizes, with 
relatively wide lattice-bars. The larger spines are elongate-conical ; 
they are connected with the test by slender tripodal extensions 
of their bases. The secondary spines are numerous and minute. 


* Quart. Journ. Geol. Soc. vol. li (1895) p, 637 & pl. xxvi, fig. 6, 
Q.J.G.8. No, 217. | E 


50 DR. G. J. HINDE ON THE RADIOLARIA INTHE  [Feb. 1899, 


Diameter of test, 0-105 mm.; width of pores, 0-005 to 0-015 mm. ; 
length of radial spine, 0:1 mm.; of secondary spines, 0°01 mm. 
In the specimen figured the radial spines are broken away, and 
only their stumps remain; but a complete spine, in position on 
another specimen, is shown in the figure. In siliceous limestone. 
No. 245 3, 


HELIosPH@RA CLAVATA, sp. nov. (PI. VIII, fig. 28.) 


Framework of test delicate; the pores are rounded or polygonal, 
and unequal in size; there are four or five robust primary spines 
shown: these taper very gradually, and terminate obtusely ; the 
secondary spines are conical and pointed. Diameter, 0°075 mm. ; 
width of pores, 0°0075 mm.; length of primary spines, 0-1 mm. ; 
thickness, 0°022 mm. In siliceous limestone. No. 2453. | 


Genus Hetiosoma, Haeckel. 


The test consists of two latticed spheres (a cortical and a medul- 
lary), with large radial, and smaller and more numerous secondary 
spines. 


HELIOsOMA ECHINATUM, Sp. nov. (Pl. IX, figs. 1 & 2.) 


The cortical test has small lattice-pores; the medullary test is 
small, with very slender lattice-framework and polygonal pores; 
the larger radial spines are robust and gradually tapering, the 
smaller are very numerous, slender needle-shaped, and unequal in 
length. Diameter of cortical test, 0-16 to 0°22 mm.; thickness of 
wall, 0-015 mm.; diameter of medullary test, 0°05 mm. ; length of 
primary spine, 0°27 mm.; thickness at base, 0-03 mm. ; secondary 
spines, 0°02 to 0°1 mm. in length. Not uncommon. Occurs in 
volcanic tuff. No. 387 p. 

Only sections of this form are as yet known, and in the specimens 
figured one alone of the radial spines in each case is preserved, but 
there are indications of the broken-off bases of others. The radial 
spine of fig. 1 probably represents merely the central portion of 
the spine ; it may originally have been equally as stout as that in 
fig. 2. The medullary test is faintly shown in fig. 1, but cannot be 
distinguished in fig. 2, which is infilled with somewhat granular 
silica. Both the figured specimens occur in the same microscopic 
section of the rock. 


Hoetiosoma Paron”, sp. noy. (PI. IX, fig. 3.) 


In its main features this form resembles the preceding, but the 
pores of the outer test are circular; the medullary test has not been 
preserved ; the secondary spines are of a stout character, and there 
is the lower portion of an unusually thick radial spine. Diameter 
of test, 0°16 mm.; width of pores, 0°01 mm.; basal thickness of radial 
spine, 0°04 mm.; length of secondary spines, 0-ll mm. Rare. 
In siliceous limestone. No. 2453. Named in honour of Prof. 
C. F. Parona, of Turin. 


Vol. 55. | DEVONIAN ROCKS OF NEW SOUTH WALES. 51 


Order PRUNOIDEA, Haeckel. 


Genus E.iipsrptum, Haeckel. 


The test is a simple latticed ellipsoid, with radial spines on its 
surface. 


KLLIPSIDIUM CASTANEA, sp. nov. (Pl. IX, fig. 4.) 


Test small, with subequal rounded pores and lattice-bars about 
half the width of the pores; the spines are short and conical. 
Major axis of test, 0°095 mm.; minor, 0°075 mm.; width of pores, 
0-01 mm.; length of spines, 0:°015 mm. Rare. In siliceous lime- 
stone. No, 2453, 


Genus ELLIPSOSTIGMA, gen. noy. 


The test is a simple latticed ellipsoid, with four radial spines, 
which proceed from a central spot or a short bar in the centre of 
the test. Secondary spines are also present. 

The nearest genus with which this may be compared is Stigmo- 
spheerostylus, Rust, in which six radial bars extend from the centre 
of a spherical test.’ 


ELLIPSOsTIGMA AUSTRALE, sp. nov. (Pl. IX, fig. 5.) 


The test is oval, with minute rounded pores; in the centre four 
straight rods extend from a small bar in different directions to 
beyond the circumference of the test, so as to form short conical 
spines. Minute secondary spines arise from the nodes of the mesh. 
Major axis of test, 0:12 mm.; minor, 0:1 mm.; width of pores, 
0-006 mm.; radial spines, 0°03 mm. Rare. In siliceous lime- 
stone. No. 2453. 


Genus STAURODRUPPA,® gen. nov. 


The test consists of two concentric latticed ellipsoids, cortical 
and medullary, with four radial spines, disposed crosswise in two 
axes, but not always at right angles. The radial spines may all be 
similar, or those of the same axis may be similar; but, owing to the 
imperfect preservation in the fossil forms, this feature can seldom 
be ascertained with certainty. This genus corresponds with 
Staurolonche, Haeckel, and Stawrolonchidium, Haeckel, in the 
Spheeroidea. 


STAURODRUPPA PRHELONGA, Sp. noy. (PI. IX, fig. 6.) 


The cortical test has a smooth surface; the pores are about as 
wide as the lattice-bars. The medullary test is only shown in 
section. ‘The radial spines appear to be in pairs ; those of the major 
axis are prismatic, very long and stout, and those of the transverse 

1 "EAXer us, ellipse ; oriypa, spot. 
? Palzontographica, vol. xxxviti (1892) p. 142. 
* Zraupos, cross; dpimma, olive. 
B2 


52 DR. G. J. HINDE ON THE RADIOLARIA INTHE  [Fcb. 1899, 


short and slender. Major axis, 0°12 mm.; minor, 0-1 mm.; thickness 
of wall, 0°01 mm. ; width of pores, 0-007 mm.; longest polar spine, 
0-22 mm., and thickness at base, 0°045 mm. ; transverse spine, 0°06 
by 0:015 mm. The medullary test is 0:°055 by 0°04 mm. In 
siliceous limestone. No. 2453. The lower axial spine in the 
specimen figured is imperfect ; it seems to have been originally as 
thick as the spine opposite to it. 


STAURODRUPPA NUCULA, sp. nov. (Pl. IX, fig. 7.) 


The cortical test is regularly oval in outline; the lattice-frame 
of the oval medullary test is very delicate; the pores are minute 
and rounded or subangular. ‘The radial spines are keeled or 
prismatic, and nearly equal in length. Major axis of cortical test, 
0-105 mm., and minor, 0:085 mm.; major and minor axes of inner 
test, 0°05 and 0:035 mm. Length of spines, 0:09 to 0°11 mm. ; 
thickness at base, 0°03 mm. In siliceous limestone. No. 2453. 


STAURODRUPPA NANA, sp. nov. (PI. IX, fig. 8.) 


The cortical test small, short-oval, thin, with circular pores; the 
medullary regularly oval, very delicate, with subangular pores. 
The radial spines are short, slender, conical, probably imperfect. 
Outer test, 0:065 by 0°06 mm.; inner, 0:035 by 0:08 mm.; width of 
spines, 0:02 mm. Rare. In siliceous limestone. No. 2453, 


Genus Sponeoca@ rta,! gen. nov. 


The test is ellipsoidal, with an irregularly reticulate or spongy 
framework and central cavity, without medullary shell. There are 
two opposite radial spines, and within the test slender rods similar 
to those in Stegmosphera, Haeckel, or a central spicular body. 

This genus may be compared with Spongoprunum, Haeckel,? 
in which, however, the interior cavity of the test is filled with 
a reticulate or spongy structure. 


SPONGOC@LIA CITREUM, sp. nov. (Pl. IX, fig. 18.) 


The test is regularly oval in outline, with a minutely porous wall 
of reticulate tissue, and within it are delicate siliceous rods, now 
displaced. At either pole there is a short, stout, keeled, radial 
spine, probably similar originally. Length of test, 0°165 mm.; 
width, 0°15 mm.; length of radial spine, 0-09 mm., and thickness at 
base, 0°05 mm. In volcanic tuff. No. 387 p. 


SPoNGoc@L1a oLiIva, sp. nov. (Pl. IX, fig. 19.) 


The test is oval, with a minutely reticulate structure; in the 
centre there isa small three-rayed spicular body. At one pole is 
a slender elongate radial spine, and at the opposite a much shorter 
one. Length of test, 0-125 mm.; breadth, 0-1 mm.; principal spine, 
0:14 mm. in length. In siliceous limestone. No. 2453. 


1 Yréyyos, sponge ; cotXos, hollow. 
2 Challenger Report on the Radiolaria, Zool. vol. xviii, pt. i (1887) p. 347. 


Vol. 55.] DEVONIAN ROCKS OF NEW SOUTH WALES. 53 


Order DISCOIDEA, Haeckel. 


Genus ‘Turopiscus, Haeckel. 


The test isa simple latticed disc, with three marginal radial 
spines at equal or unequal distances apart. 


THEODISCUS HASTATUS, sp. nov. (PI. IX, fig. 9.) 


Test small, with rounded pores and slender, polygonal lattice- 
bars. Radial spines robust, keeled, and acutely pointed, at unequal 
distances apart. Diameter of test, 0:075 mm.; width of lattice-pores, 
0-005 mm.; length of spines, 0:08 to 0°15 mm.; thickness at base, 
0°025 mm. In volcanic tuff. No. 387. 


Genus TrocHopiscus, Haeckel. 


The test is a simple latticed disc, with ten or more marginal 
radial spines. 


TRocHODISCUS PLANATUS, sp. nov. (PI. LX, fig. 10.) 


Test compressed, with rounded subequal pores and bars about 
half the width of the pores. A number of stout, short, conical 
spines extend from the margins. In the centre of the test is a 
minute three-rayed spicule, closely resembling the detached forms 
which have been referred to Spherozoum. Diameter of test, 
0-17 mm. ; width of lattice-pores, 0:01 mm.; length of spines, 0°02 
to0-05mm. In siliceous limestone. No. 2453. 


Genus Trractiscus, Haeckel. 


The latticed disc has a simple medullary test, and three radial 
spines on the margin. 


TRIACTISCUS LANCEHOLA, sp. nov. (Pl. IX, fig. 11.) 


_ The cortical test has very minute rounded pores; the lattice-bars 
are nearly as wide as the pores, and are furnished with minute 
spines. The medullary test is only indicated by a fragment of the 
mesh, with pores larger than those of the cortical test. Of the radial 
spines only two are preserved, and one of these is imperfect; the 
other is lanceolate in form, with a strong longitudinal keel. 
Diameter of cortical test, 0°105 mm.; width of pores, 0:005 mm.; 
radial spine: length, 0°115 mm., and greatest width, 0°04mm. In 
volcanic tuff. No. 387 p. 


Genus Distriactis, Haeckel. 


The latticed disc has a simple medullary test, and six radial 
spines extending from the margin in the equatorial plane. 


DisTRIACTIS VETUSTA, sp. Noy. (Pl. IX, fig. 12.) 
Both the outer and inner tests are oval in outline; the pores of 


54 DR. G, J, HINDE ON THE RADIOLARIA IN THE  [Feb. 1899, 


the medullary test are rounded ; the radial spines are slender, conical, 
now unequal in length, probably due to imperfect preservation : the 
longest equals the radius of the test. The proximal ends of the 
spines extend for a short distance within the medullary test. 
Diameter of cortical test, 0°15 by 0°13 mm.; of medullary, 0-05 mm.; 
of pores, 0:008 mm.; longest spine (measured from margin of test) 
0-07 mm., and thickness, 0°01 mm. Rare. In siliceous limestone. 
No. 245 3. 


Genus Hetiosestrum, Haeckel. 


The test is similar to that of Distriactis, but the radial spines are 
eight in number; occasionally there are seven or nine. 


HELIOsESTRUM NIGRUM, sp. nov. (PI. IX, fig. 13.) 


The test is only shown in section; it is slightly oval in outline ; 
the medullary test is about one-third the diameter of the cortical ; 
there are eight radial spines, but only one of these is preserved com- 
plete ; it is about twice the diameter of the disc, and slightly curved 
near the end. Diameter of outer test, 0°135 by 0°11 mm.; of inner, 
0-038 mm.; length of spine, 0°24 mm., and thickness, 0°02mm. In 
siliceous limestone. No. 245 3. 


Genus Sponeopiscus, Haeckel. 


The test is a flattened disc, of irregularly reticulate or spongy 
structure throughout, without marginal appendages. 


SPONGODISCUS PUNCTUS, sp. nov. (Pl. IX, fig. 14.) 


The disc is nearly circular in outline, with very minute pores 
and irregularly reticulate framework without radial bars. Diameter, 
0:14 mm.; pores, about 0-003 mm. Rare. In volcanic tuff. 
No. 387 p. 


SPONGODISCUS ACINUS, sp. nov. (Pl. IX, fig. 15.) 


The test is oval in outline, depressed, the structure minutely 
reticulate, and the margin is roughened with small prickles. 
Diameter of test,0°09 mm. Closely allied to the preceding; it may 
be distinguished by its prickly surface and oval outline. Rare. In 
siliceous limestone. No. 2453. 


SPONGODISCUS CRIBRARIUS, sp. nov. (Pl. IX, fig. 16.) 


The test is nearly circular in outline, depressed ; the reticulate 
structure is minute, though less so than in the preceding species, 
and the pores are consequently larger. No radial bars. Diameter 
of test, 0°2 mm.; width of pores, 0°005 to 0°01 mm. _ Rare. 
In voleanic tuff. No. 387p. This form may be compared with 
Sp. expansus, Hinde, from the Cretaceous at Fanny Bay, Port 
Darwin, which has a finer structure.’ 


1 Quart. Journ. Geol. Soc. vol. xlix (1893) p. 224 & pl. v, fig. 6. 


Vol. 55.] DEVONIAN ROCKS OF NEW SOUTH WALES. sy3) 


SPoNGODISCUS SCUTULATUS, sp. nov. (Pl. IX, fig. 17.) 


The test is elongate-oval in outline, depressed ; the central area 
is nearly free from tissue, but there is no definite inner test; the 
structure is very minute and irregularly reticulate, with numerous 
radial bars, which are not extended beyond the margin. Length of 
test, 0-185 mm.; breadth, 0°12 mm.; width of pores, 0°005 mm. 
In siliceous limestone. No. 2453. 


Genus SponegotoncHeE, Haeckel. 


Test discoidal, of irregular reticulate or spongy structure, with 
two opposite radial spines. 


SPoNGOLONCHE LENS, sp. nov. (Pl. IX, fig. 20.) 


The test is elongate-oval ; the wall-structure is minutely porous ; 
the reticulate tissue is disposed in four or five concentric layers, 
and there are also traces of a radial arrangement as well. There 
is an oval space in the centre of the test, now partly filled with 
amorphous matrix. At either end of the main axis is a stout 
conical spine. Length of test, 0°22 mm.; breadth, 0:16 mm.; length 
of spines, 0:25 mm. and 0185 mm. LKare. In siliceous limestone. 
No. 245 3. 


Genus Sponeorripus, Haeckel. 


Test discoidal, of porous, reticulate or spongy framework, with 
three solid radial spines on the margin. 


SPoNGOTRIPUS PATELLA, sp. nov. (Pl. IX, fig. 21.) 


The test is depressed, rounded in outline ; the surface-structure is 
irregularly reticulate, but beneath this the framework has a radial 
arrangement, and looks as if numerous slender bars extended from 
the borders of a central area in which no structure is shown. Only 
two radial spines are preserved. Diameter of test, 0°25 mm.; 
longest spine, 0°16 mm. ; thickness at margin, 0-‘04mm. Rare. In 
voleanic tuff. No. 387. 


SPONGOTRIPUS FENESTRATUS, sp. nov. (Pl. IX, fig. 22.) 


The test is oval in outline, depressed; the surface-reticulation in 
the central portion of the test has circular and subangular pores ; 
nearer the margins the reticulations are finer, and a radial arrange- 
ment prevails. ‘Two stout, conical, radial spines are preserved, and 
the base of a third. Diameters of test, 0°175 by 0-14 mm.; length 
of spines, 0-1 to 0'115 mm., and thickness, 0°035 mm. In siliceous 
limestone. No. 2453. The upper part of the specimen figured 
is incomplete. 


56 DR. G. J. HINDE ON THE RADIOLARIA IN THE  [Feb. 1899, 


Subclass VASSHLLARIA, Ehrenberg. 
Order PLECTOIDEA, Haeckel. 


The rudimentary skeleton consists of simple or branched radial 
spines, arising from.a common central point or central rod. The 
branched spines may be connected together by a loose, open mesh- 
work, 


Genus PLagracantaHa, Claparéde. 


The skeleton is formed by three radial spines arising from a 
common central point, and corresponding to the edges of a three- 
sided pyramid. 


PLAGIACANTHA AUSTRALIS, sp. nov. (Pl. IX, fig. 23.) 

Only two of the spines and the basal portion of the third are 
shown; they are nearly straight, simple, unequal in length, circular 
in section, and gradually tapering. On their upper surfaces 
there are close-set, minute pustules or blunted spines. Length 
of spines, 0:215 to 0°18 mm.; thickness at centre, 0°02 mm. In 
siliceous limestone. No. 2453. 


Genus Praconiscus, Haeckel. 


The skeleton consists of four unequal radial spines arising from 
a common central point: one vertical or apical spine being opposed 
to three divergent or basal spines. 


PLAGONISCUS SIMPLEX, sp. nov. (PI. IX, fig. 24.) 


The three basal spines are simple, straight, conical, and in one 
plane ; the vertical spine slender and curved. Length of basal spines, 
0:06, 0°07, 0°08 mm.; thickness, 0°01 mm.; length of vertical, 
0085 mm. In siliceous limestone. No. 2453. 


PLAGONISCUS CRISTATUS, sp. nov. (Text-fig a, p. 57.) 


The basal spines, of which only two are shown, are simple, un- 
even, with minute prickles; the apical spine curved, compressed, 
with stout prickles on one edge. Length of basal spines, 0°18 and 
0-22 mm.; thickness, 0°012 mm.; length of apical spine, 0°18 mm. 
In siliceous limestone. No. 245 3, 


PLAGONISCUS COLLIGATUS, sp. nov. (Text-fig. b, p. 57.) 


The apical spine is fusiform, tapering to both ends and with 
very minute prickles near its point; the basal spines, of which 
only two are shown, are straight near their origin, they are then 
bent downwards and become furcate; the rays are unequal. The 
basal spines are connected with the apical by oblique siliceous 
beams. Length of apical spine, 0°185 mm.; thickness, 0°015 mm. ; 
length of basal spine to end of furcate ray, 0'185 mm. Rare. In 
siliceous limestone. No. 245 3. 


Vol. 55.] DEVONIAN ROCKS OF NEW SOUTH WALES. 57 


PrLagoniscus (?) veTUSTUS, sp. nov. (Text-fig. c, below.) 


The apical spine is elongate, with projecting lateral spines on either 
margin; the basal spines are straight or slightly curved: they are 
now imperfect. Beneath the centrai point is a short straight spine, 
which may either be an extension of the apical spine or an inde- 
pendent spine; in this latter case the form can ase be included 
in ges. Length of apical spine, 0-24 mm.; thickness, 
0015 mm.; the longest basal spine measures 0: 105 mm. In 
siliceous limestone. N 0, 245 3. 


['The figures are all magnified 200 diameters. ] 


a = Plagoniscus cristatus, sp. nov. e = Pl. (?) vetustus, sp. nov. 
b = Pl. colligatus, sp. nov. a PF (isp 


Praconiscus (?) sp. (Text-fig. d, above.) 


This form has, like the preceding, a short spine below the central 
point of the basal spines and the apical; both the apical and basal 
spines are furnished with stout marginal prickles projecting at 
right angles. Length of apical spine (imperfect), 0-2 mm.; thickness, 
0-015 mm. In the same rock with the preceding. 


08 DR. G. J. HINDE ON THE RADIOLARIA IN THE [TF eb. 1899, 


The following list shows the genera, and the numbers of species 
in each genus, of radiolaria, which have been recognized in the 
Devonian rocks at Tamworth (New South Wales) :— 


Order BrnorpEA. Species. Order Prunomna. Species. 
Sph@rozoum ...cecseeeee ig Hlbipsidium...ccdossconaes 
| Ellipsostigma ....0.0.0. 1 
Order SPH#ROIDEA. Staurodruppa  ...eseres 3 
Cemosphera  vscesssoeees 2 Spongocelia ......0.000- 2 
PQGS PREG |... eiecekueas 1 
Phodosph@ra ....1.1+00. ul Order DiscorpEA. 
Spongoplegma .......6 1 TRCOdiSCUS: 5.0m semecner 1 
DOrySPNner@ \wicccas 1 Trochodiscus ........ 1 
AXiphosphera ...sc.sseee if TTUOGISCUSs: secewedeen 1 
Stylosphera .......00008 2 DistriGevis sos cates-ee- 1 
STAUTOSPHETA..1. 0.000000 2 Heliosestrum ......... 1 
Stauroloncheé .....-+.+4. 4 Spongodiscus .......4+ 4 
Staurolonchidium ...... 1 Spongolonche ........- £ 
EP UWOMCRE ci. achinaense es 3 Spongotripus ......... 2 - 
Acanthosphera ........- 2 
FLCMOSPhETA ...000000-. 4 Order PLEcTOIDEA. 
FICUIOSOWG srax-ceacse nian 2 Plagiacantha ......... 1 
Plagoniscus ......... 5 
No. of No. of 
Order. Genera. Species. 
Below Gea:: asninsecngesmeer he 1 1 
Sphzeroidea «een -cwcrsi: 14 27 
PRUMOIGESD. iaiepesessaseeshee 4 7 
Darsieo tea taste sn ees. 8 12 
P¥eetordeal 555 et Ae 2 6 
29 53 


LV. GENERAL CHARACTERS AND AFFINITIES OF THE RADIOLARIA. 


From the preceding list it is seen that 53 species belonging to 
29 genera of radiolaria have heen determined from the Devonian . 
rocks of Tamworth. Jour genera and all the species are considered 
as new. ‘The apparent absence of known species in these deposits 
will appear less remarkable when we remember that our present 
knowledge of Paleozoic radiolaria is limited to those occurring in 
a few outcrops in Central and Northern Europe, and that those 
herein described are the first known from older rocks in the Southern 
Hemisphere. Considering the great thickness of the Tamworth 
radiolarian deposits, and the immense number of the organisms in 
them, one might have anticipated that a greater variety of forms 
would be found. It is probable indeed that the 53 species figured 
do not represent a moiety of those present in the rocks, for com- 
paratively few fragments of the beds have as yet been microscopically 
examined, and many of the organisms in these have had to be passed 
over as too fragmentary for description. 

The distinguishing feature of the Tamworth radiolaria is the 
very large proportion of forms with central or medullary latticed 
tests and radial spines. A glance atthe figures in the accompanying 


Vols55.) DEVONIAN ROCKS OF NEW SOUTH WALES. 59 


plates shows the great number of forms possessing these characters, 
but the proportion is even larger than the figures suggest, for the 
forms without radial spines are comparatively rare, while the 
spined forms are so abundant that in some thin sections no others 
are recognizable. This remark, however, applies only to the dark 
siliceous limestones which have had the calcite removed by acid; for 
the radiolaria, in sections of the chert and of the claystones, appear 
for the most part to be simple spherical or elliptical forms without 
central tests and without radial spines. It is not at all probable 
that such marked differences of character should occur in the forms 
preserved in the cherts and claystones interstratified with the 
siliceous limestones, and the apparent absence of the spines and 
inner tests in the former beds may be attributed to the less perfect 
condition of preservation of the radiolaria contained in them. 

_As regards size, the Tamworth radiolaria appear to be relatively 
small. The tests, in the large majority, range between 0°06 and 
0-25 mm. in diameter; exceptionally, larger forms occur: thus, for 
example, in a section of black chert (No. 274 ¢) a simple oval form 
measured 0°44 by 0°34 mm. 

The order Spheroidea is the most numerously represented in the 
Tamworth rocks; somewhat more than half the species are included 
in this division. With the exception of Trilonche, gen. noy., the 
species belong to genera previously recognized in Paleozoic rocks. 
With few exceptions these spheroidal radiolaria possess radial spines. 

Three of the 4 genera of Prunoidea are new; they are charac- 
terized mainly by the development of the radial spines in connexion 
with the ellipsoidal test. 

The 12 species of Discoidea belong to genera already known, but 
5 out of the 8 genera of this division had not previously been re- 
corded from Palzeozoic rocks. 

The only representatives of the subclass Nassellaria are spicular 
bodies included in the order Plectoidea. These simple forms might 
at first be mistaken for sponge-spicules, but neither in fossil nor in 
recent sponges are spicules, similar in detail to these, known to 
occur. 

As negative features of the Tamworth radiolarian fauna may be 
mentioned the absence of the Discoidal genera Lithocyclia, Poro- 
discus, Amphibrachium, and Rhopalastrum, common in nearly all 
Mesozoic and Paleozoic radiolarian deposits hitherto described, and 
the yet more notable deficiency of any representative form of the 
order Cyrtoidea. 

The corals in the limestones associated with the radiolarian rocks 
at Tamworth (which have been determined by Mr. R. Etheridge, 
jun.) indicate clearly the Devonian age of the latter. The only 
rocks of this period containing radiolaria hitherto known are those 
- described by Dr. H. Riist from the Ural Mountains and from Hesse, 
considered to be Lower Devonian in age, and from the Harz and 
near Goslar, which are believed to be Upper Devonian.' From these 


1 Palzontographica, vol. xxxviii (1892) pp. 1138, 114, 122. 


60 DR. G. J. HINDE ON THE RADIOLARIA IN THE _[Feb. 1899, 


rocks 64 species of radiolaria, belonging to 37 genera, were described, 
but only 7 of these genera are common with those at Tamworth, 
and no near relationship is apparent between the Devonian radio- 
laria of Central and Northern Europe and those of the same period 
in Australia. <A similar want of affinity is also shown, if a compari- 
son be made with the radiolaria of the Lower Culm or Carboniferous 
described by Rist from the Harz, Sicily, Russia, etc.,' and by Hinde 
& Fox from the South-west of England.’ 

The Tamworth radiolaria, however, show as a whole a genera 
correspondence with the radiolarian fauna from the phosphorites 
and siliceous shales of Ordovician (Lower Silurian) age occurring at 
Cabriéres in Languedoc, which have been described by Riist,’ and 
also with that in the cherts of the Southern Uplands of Scotland of 
a corresponding age.* In both these deposits the predominant 
radiolarian forms belong to the Spheroidea with radial spines and 
medullary tests. In the Scottish beds they appear to belong rather to 
the group with spongiform than to that with regularly-latticed tests, 
but some doubt is thrown on this feature from the poor preservation 
of the fossils. In the same beds there are also some of the peculiar 
spicular bodies referred to primitive forms of Plectoidea, of a similar 
character to those at Tamworth. And finally it may be mentioned 
that the radiolarian fauna of Cabriéres and Scotland resembles that 
of New South Wales in the absence of examples of the Cyrtoidea. 

The same features which distinguish the New South Wales 
Devonian radiolaria from those in the Paleozoic deposits of other 
areas serve still more strongly to mark them off from the radiolaria 
of Mesozoic and Tertiary rocks. In no respect is this difference 
more manifest than in the apparent absence of the Cyrtoidea, which 
are so numerously represented in the Jurassic, Cretaceous, and 
Tertiary rocks that Haeckel stated in the Challenger Report ° 
that the majority of all the fossil radiolaria then known belonged 
to this group. This observation was made at a time when the 
existence of Paleozoic radiolaria had been scarcely recognized, but 
the evidence since obtained from Scotland, France, Germany, and 
now from New South Wales, points to the conclusion that the 
predominant forms of the Paleozoic radiolaria belonged to the 
Spheroidea with medullary tests and radial spines, and that the 
Cyrtoidea were either not represented or formed but a small minority 
of these organisms in the earlier radiolarian rocks. 


V. Fossils ASSOCIATED WITH THE RADIOLARIA. 


Judging from the rock-specimens that I have examined, other 
fossils besides radiolaria are extremely rare in the same beds, and 


1 Palxontographica, vol. xxxviii (1892). 

2 Quart. Journ. Geol. Soc. vol. li (1895) pp. 609-668. 

3 Paleontographica, vol. xxxviii (1892) pp. 114, 122. 

4 Ann. & Mag. Nat. Hist. ser. 6, vol. vi (1890) pp. 40-59. 
5 Zool. vol. xviii, pt. ii ( 1887) p. 1126. 


Volos 5: | DEVONIAN ROCKS OF NEW SOUTH WALES. 61 


they are limited to a few spicules of siliceous sponges and some 
minute spined or dentate plates, probably of some invertebrate 
organism. The sponge-spicules are small, detached, fusiform acerates 
and cylinders, from 0:16 to 0°36 mm. in length, which pro- 
bably belong to monactinellid sponges. No trace of any diatoms 
has been observed among the radiolaria of the siliceous lime- 
stones; if any had been present originally, it is probable that they 
would have been preserved, seeing that the equally delicate lattice- 
structures of the radiolaria have, in numerous instances, remained 
practically unaffected by the fossilization. 

As mentioned by Messrs. David & Pittman, impressions of Lepido- 
dendron australe are present in the same rock with numerous 
chalcedonie casts of radiolaria, and specimens of the same plant also 
occur in beds of tuff on two or three horizons. It may be rash to 
express an opinion without having seen the facts in the field, but it 
does not seem improbable that both the plant-fragments and the 
tuff may have been carried by the wind and wave-currents to some 
distance from land and deposited in deep water, in the same manner 
as the masses of leaves, pieces of bamboo, sugar-cane, and other 
débris which Prof. A. Agassiz dredged up from a depth of over - 
1000 fathoms, and at a distance of 10 to 15 miles from land, off 
Caribbean Islands.’ 

It does not yet appear that radiolaria have been found in the 
bluish coral-limestone associated with the radiolarian series at 
Tamworth, which in places reaches a thickness of 1000 feet. In 
microscopic sections of this rock (No. 258 8) which I have examined 
there were only portions of corals which had been replaced by 
crystalline calcite. This rock has probably been formed under 
conditions, as to depth, different from those in which the radiolarian 
limestones and claystones were deposited. 


VI. Summary. 


In the important series of radiolarian rocks, some thousands of 
feet in thickness, which have been traced out by Messrs. David & 
Pittman in New South Wales at Bingara, Barraba, and Tamworth, 
these organisms occur in beds of chert, siliceous limestones, clay- 
stones and shales, and in sedimentary volcanic tufts. In the cherts 
the radiolaria are usually thickly grouped together, filling the rock; 
they are nearly entirely in the condition of casts infilled with clear 
silica and without structure, thus precisely similar to those in chert 
with radiolaria known in other parts of the world. In the siliceous 
limestones, on the other hand, the radiolaria not infrequently 
retain their delicate structures practically unaltered by fossilization ; 
they are now embedded in a groundmass of crystalline calcite which 
has infiltrated their hollow spaces, and when this is eliminated by 
weak acid the rock is seen to be composed of an entangled tissue 
of entire and fragmentary forms and fine débris. The claystones 


1 ‘Three Cruises of the Blake, 1877-1880, Bull. Mus. Comp. Zool. vol. xiv 
(1888) p. 291. 


62 DR. G, J. HINDE ON THE RADIOLARIA INTHE  [Feb. 1809, 


are similarly filled with radiolaria which have been infiltrated by 
very fine clayey sediment, which is not removable by acid, and they 
are therefore less recognizable in microscopic sections, though they 
are shown weathered out on the surface of the rock. In the tuff- 
rock the radiolaria occur singly, scattered in the calcite which 
cements them and the tuff-fragments together; they retain their 
structures equally as well as those in the siliceous limestones, and, 
not being crowded, the details of their forms can be more readily 
distinguished in microscopic sections. 

Fifty-three species, belonging to 29 genera, have been recognized ; 
4 genera and all the species are regarded as new, nearly all are 
included in the division of the Spumellaria, but a few primitive 
examples are referable to the Nassellaria. The predominant 
majority of the radiolaria are Spheroidal and Prunoidal forms with 
medullary tests and radial spines. There is a singular absence of 
many Discoidal genera common in other fossil radiolarian faunas, 
and likewise of forms of Cyrtoidea. 

The geological age of the radiolarian rocks is proved to be 
Devonian by the occurrence, in the lower part of the Tamworth 
series, of corals characteristic of this period. The radiolaria, 
however, do not show any close affinity with those which have been 
described from Devonian rocks in Europe, but in some positive and 
negative characters they agree with those of Ordovician age from 
the South of Scotland, Cornwall, and from Cabriéres in Languedoc. 

As a rule, no other organisms beyond a very few simple sponge- 
spicules and some minute dentate plates of uncertain character 
occur in the same rocks with the radiolaria, but on two or three 
limited horizons fragments of Lepidodendron australe are present in 
claystones and tuffs, together with radiolaria. 

In the coral-bearing limestones of the Tamworth section radio- 
laria have not as yet been found. On the other hand, in the 
radiolarian siliceous limestones no calcareous organisms have been 
recognized, and thus the source of the limestone in these rocks 
remains uncertain. 

The radiolarian deposits of New South Wales are by far the 
most extensive of any hitherto known. For the formation of so 
great a thickness of rock, composed principally of extremely fine 
calcareous or clayey materials filled with the remains of these 
microscopic organisms, an enormous period of quiet sedimentation 
must be conceded. The radiolarian claystones of Tamworth may 
be compared with the recent red clays with radiolaria of the 
Challenger Report, and the tuff-rocks with the same forms 
sparsely scattered in them also find their parallel in the volcanic 
fragmentary materials which were dredged up by the Challenger 
from the depths of the Southern Ocean. 


In conclusion I wish to express my great obligations to my 
friend, Mr. J. J. H. Teall, F.R.S., for his advice and assistance in 
ascertaining the character of the tuff-rocks containing radiolaria. 


Vol. 55.] DEVONIAN ROCKS OF NEW SOUTH WALES, 63 


EXPLANATION OF PLATES VIII & IX. 


[The specimens figured are all from the Devonian rocks at Tamworth (New 
South Wales), and they are all drawn to the same scale of 200 diameters. 
The slides containing these specimens are in my own collection. | 


Puate VIII. 


Figs. la-le. Spherozoum sp. Detached, apparently three-rayed, spicules. 
Fig. 2. Cenosphera scitula, sp. nov. 

3. a affinis, sp. nov. 

4, Liosphera, sp.ind. Seen in section. 

5. Rhodosphera Ruesti, sp. nov. Section. 

6. Spongoplegma australe, sp. nov. 

7. Dorysphera echinata, sp. nov. 

8. Xiphosphera minax, sp.nov. Section. 

9. Stylosphera obtusa, sp. nov. Section. 


10. yA vetusta, sp. nov. The outer test in section. 
11. Stawrosphera(?) ornata, sp. nov. 

1s i pusilla, sp. nov. 

13. Staurolonche Davidi, sp. nov. 

14. a tenella, sp. nov. The outer test in section. 
15. a laterna, sp. noy. 3 - nA 
16. ‘ scitula, sp. Nov. 


17. Staurolonchidium obliquum, sp. nov. The outer test in section. 
18. Trilonche vetusta, gen. et sp. nov. The outer test in section. 


19. ” oP) var, a. 2 ”? ” 
74D. ee Pittmani, sp. nov. us - By 
22. ms elegans, 8p. Nov. a “ 5 
23. Acanthosphera australis, sp.nov. In section. 
24. 5; Ltheridgei, sp. nov. 
25. Heliosphera robusta, sp. nov. In section. 
6. - Tumworthi, sp. nov. a 
PAT af Jenestrata, sp. nov. A specimen in which the spines are 
broken away ; also one of the spines detached. 
28. #1 clavata, sp. nov. ; 
Puate IX, 


Figs. 1, 2. Heliosoma echinatum, sp. nov. In section. 
Fig. 3. Heliosoma Parone, sp. nov. 
4. Hillipsidiwm castanea, sp. nov. 
5. Hilipsostigma australe, gen. et sp.nov. In section. 
6. Staurodruppa prelonga, gen. et sp. nov. Br 
Fi a nucula, sp. nov. 
8. nana, sp. Nov. 
9. Theodiscus hastatus, sp. nov. 
10. Trochodiscus planatus, sp. nov. 
11. Triactiscus lanceola, sp. nov. 
12. Distriactis vetusta, sp. nov. In section. 


13. Heliosestrum nigrum, sp. nov. R 
14. Spongediscus punctus, sp. nov. 

iS, a acinus, 8p. NOV. 

16. s cribrarius, sp. NOV. 

Ait. a scutulatus, sp. DOV. 

18. Spongocelia citreum, gen. et sp. nov. 
ge e oliva, sp. nov. 


20. Spongolonche lens, sp. nov. In section. 
21. Spongotripus patella, sp. nov. 

22. He Senestratus, sp nov. 

23, Plagiacantha australis, sp. nov. 

24, Plagoniscus simples, sp. nov. 


64 DEVONIAN RADIOLARIA FROM NEW SOUTH WALES. _[ Feb. 1899, 


Discussion (ON THE TWO FOREGOING PAPERs). 


Mr. G. A. Stonrer said that the paper was an important and 
very welcome contribution to the geology of the north-eastern 
portion of New South Wales, not only on account of the discovery 
of radiolaria, but also because Lepidodendron australe was shown to 
have had a greater range than had been previously supposed, and 
the position of the garnetiferous limestone had been ascertained. 
The tuffs were of particular interest to the speaker, as he had found 
that near the diamond-properties at Bingara tuffs and volcanic 
breccias were well developed; they contain fragmentary shells, 
and are interbedded with shales characterized by Lepidodendron 
australe, 

Prof. Sotzas, in complimenting the Authors on their work, 
commented on the shallow-water character of the deposits, and 
maintained that radiolarian cherts were by no means an infallible 
indication of abyssal conditions. The associated rocks in the 
Arenig Series, Culm Measures, and, as we now know, in the Devo- 
nian, were not of the nature of deep-sea deposits. 

Prof. Warts called attention to the great thickness of the radio- 
larian deposit, and remarked that the extraordinary point about 
this deposit and those in Devon, California, and Southern Scotland 
was the entire absence of terrigenous material. The thickness of 
the deposits indicated the lapse of a great interval of time. 

Dr. Hinpe, in reply, said that Prof. Sollas was under a mis- 
apprehension in supposing that several conglomerates were inter- - 
calated in the series of radiolarian rocks at Tamworth; the Authors 
referred to one conglomerate which occurred in the highest part of 
the section, and they doubted whether even this properly belonged 
to the beds below it. The speaker still considered that the radio- 
larian strata of New South Wales, also those of the South-west of 
England and California, indicated deposition at a distance from land 
and in deep water, though to Prof. Sollas this might seem an 
‘irrational conclusion.’ 

The PresrpEnt also spoke. 


¥ 


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Quart.Journ.Geol Soc Vol.LY.PL VIL. 


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eee DIOLARIA FROM THE DEVONIAN ROCKS OF NEW SOUTH WALES. 
AlLX 200 dxcaneters. 


Pz 


A.T.Hollick del.et hth 


Quart.Journ.Geol. Soc. Vol.LV.P1.IX. 


Mintern Bros.imp. 


RADIOLARIA FROM THE DEVONIAN ROCKS OF NEW SOUTH WALES. 
All 4 200 diameters. 


(op) 
Or 


Vol. 55.] GEOLOGY OF THE GREAT CENTRAL RAILWAY. 


2. Grotocy of the Great Centra Raitway (New LEvxiension to 
London of the Manchester, Sheffield, 5 Lincolnshire Railway) : 
Ruesy to Caressy. By Brnsy Tuomupson, Esq., F.G.S., F.C.S. 
(Read November 23rd, 1898.) 


CoNTENTS, 
Page 
HALO CORY. So. v1 Sto tnagtaett cet aceton saeeee cuteness oes < 65 
HCE escripitomion phe Seckione) + s.c5.192.0e ees eee 67 
er he: Glacial Deposits. lal. s04h.. cd auscets dessa Lome 79 
BY IGE On MO SSIIG) 5.30349 Bap eee ok Jase. actcw, aiatee enact aoe 83 


I, InrropvcrTory. 


In the Report of an Excursion of the Geologists’ Association to 
Catesby in July 1896,’ I have already given an account of the 
geology of 6 miles of the new extension to London of the Man- 
chester, Sheffield, & Lincolnshire Railway (since re-named the 
Great Central Railway), reaching from Catesby to a little beyond 
Woodford: that is, from the 62nd to the 68th mile. The sections 
exposed were chiefly in Middle and Upper Lias; but, at the northern 
end of the Catesby tunnel, the capricornus-zone of the Lower Lias 
was partly cut through, all the characteristic fossils of that zone 
being found. 

The portion of the line which it is now proposed to describe, from 
Rugby to Catesby, extends from the 52nd to the 62nd mile. Two 
papers have already dealt with parts of it,” but they necessarily 
left much detail to be filled in; indeed the new matter afforded by 
excavations made since the publication of those two papers would 
probably constitute a sufficient justification for a third. 

I had seen no part of the sections about to be described until 
August 1896, and the exceptionally wet autumn of that year 
prevented a thorough examination of the slopes themselves, such as 
I fully intended te make. On renewing my acquaintance with the 
line, in the spring of 1897, I found some of the more southerly 
cuttings finished and grassed over. Fortunately the more northerly 
cuttings, towards Rugby, were developing their most interesting 
parts. I am much indebted to Mr. A. W.. H. Casson, Resident 
Engineer, for permission to examine the sections, and for valuable 
information incorporated in the accompanying figures (1-5, pp. 66, 
70, 72, 74, & 76). 

In the section of the line from Woodford to Catesby the ground 
and the various geological formations composing it rise in a northerly 
direction. From Catesby to Rugby there is a considerable fall in the 
surface of the ground (295 feet from the highest level near Catesby 
to Clifton Brook), and as the geological formations continue to rise, 
fairly low beds of the Lower Lias are met with near Rugby. 


1 Proc. Geol. Assoc. vol. xiv (1896) pp. 421-430. 

2 ‘Geol. London Extens. Manch., Sheff., & Lincs. Railway, pt. i: Annesley to 
Rugby,’ by C. Fox-Strangways; and ‘ Pt. ii: Rugby to Quainton Road, near 
Aylesbury,’ by H. B. Woodward, Geol. Mag. 1897, pp. 49-59 & S7-105, 


(ede Gu Se Nog 217. F 


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Vol. 55.] GEOLOGY OF THE GREAT CENTRAL RAILWAY. 67 


II. DeEscorirtTIon OF THE SECTIONS. 


Considering the undulating character of the country passed through, 
the cuttings are of very moderate depth, the reason for which will 
be obvious on inspecting the sections (figs. 1-5); but they are all 
through Glacial deposits or Lower Lias. 

The longest, and that which we shall examine first, if we proceed 
from north to south, in order to follow the various strata, so far 
as possible, in chronological sequence, is the section near Rugby, 
extending from about 52 miles 40 chains to 54 miles 20 chains: 
that is, approximately 1? mile. In the deepest part, near where the 
Hillmorton & Dunchurch road crosses it, it is about 45 feet deep. 

From A to B (fig. 1, p. 66) is embankment ; B to C, a viaduct cross- 
ing the London & North Western Railway ; from D to H, the whole 
cutting is composed of Boulder Clay below and Drift-gravel above. 
The Lower Lias begins to come in about H (53 miles 30 chains), 
and it continues to thicken, at the expense of the Drift-beds, to a 
little beyond the 54th mile (M, fig. 2, p. 70). 

With regard to the fossils, I may here say that, in order to avoid 
needless repetition, after each description of a zone only those forms 
will be recorded on which the identification of the zone chiefly rests; 
the others will be found in tabular form at the end (§ IV, p. 83). 
Various letters are used, in that table, to indicate the relative 
abundance of the different species. 


(a) Zone of Ammonites Turneri & A. semicostatus (fig. 1). 


About the end of May 1897 an ammonite was shown to me, at 
the office of the Resident Engineer at Rugby, different from any 
that I had myself found previously, and it proved to be Ammonites 
Turneri, but the locality from which it came was not known. On 
afterwards walking along the line I was presented with another 
form then new to me, A. Bonnardi, and told that it came from the 
foundations of an accommodation-bridge a little farther on, at a depth 
of about 35 feet from the top of the cutting. Later on I found the 
excavation, at I (fig. 1), where also were obtained numerous broken 
specimens of A. semecostatus and A. Sauzeanus, together with other 
Lower Lias fossils, mixed with, if not indeed actually embedded in 
a blue Boulder Clay. In one place were large numbers of small 
dark (phosphatic) nodules of peculiar shapes, together with others 
lighter in colour, waterworn, and sometimes bored, also rolled frag- 
ments of shells. At this time the cutting here had not been made 
to its full depth, but as to the north of it only brown Boulder Clay 
was to be found (and this was on the whole remarkably free from 
erratics, and absolutely void of fossils, so far as I could ascertain), 
and as to the south the nearest workable face was a very unfossi- 
liferous Lower Lias clay, it was not easy to interpret the section 
at I. Some six weeks later the cutting was completed sufficiently 
to show the relation of the various beds much better, though not so 
clearly as could have been wished, because the sloping had very 


closely followed upon the cutting. 
F2 


68 MR. B. THOMPSON ON THE GEOLOGY OF THE [Feb. 1899, 


It now became evident that the blue Boulder Clay was a com- 
paratively thin intermediate layer between the brown Boulder Clay 
—where the latter was present— and true Lower Lias, being, in fact, 
little more than the disturbed upper portion of this latter. It was of 
almost exactly the same colour, and contained about the same fossils, 
equally abundant, and on the whole in an equally good state of 
preservation, though some of the larger specimens were smoothed 
and striated, as were also the larger included limestone-blocks. In 
many cases it was impossible to determine with certainty whether 
a fossil came from the blue Boulder Clay or from the Lower Lias ; 
but, for the reasons stated above, I think that no serious error occurs 
in my list on account of this ambiguity. 

As before observed, I consider that the undisturbed Lower Lias 
commences a little south of H (fig. 1, p. 66), at the very bottom 
of the excavation, and from this point southward for a short 
distance eines Turneri, or other ammonites of the same group, 
are fairly abundant. A. semicostatus and A. Sauzeanus come in at 
about the same place, but continue to occur abundantly for a much 
ereater distance southward. This seems to indicate that A. Turners 
characterizes only a portion of the A. semicostatus-zone, a conclusion 
at which I had previously arrived from evidence obtained elsewhere. 

The phosphatic nodules, already mentioned as coming from the 
excavation for the foundations of the bridge at I, were afterwards 
found between I and J (fig. 1, p. 66), as a thin, irregular, but fairly 
continuous bed at an average height of 4 feet from the bottom of the 
cutting, and close under the blue Boulder Clay for some distance. 
This layer of nodules seemed to rise towards the south—that is, in a 
' direction opposite to the dip of the beds; but the seeming rise might 
be due to the fall of the cutting in a southerly direction, or to the 
irregularity of the bed. In any case, I think that this layer may be 
taken as the boundary between the semicostatus and obtusus-zones. 

The semtcostatus-zone appears to finish at about J (63 miles 
48 chains), and simultaneously the blue Boulder Clay ceases to yield 
fossils, though towards and near this point both the blue and the 
brown Boulder Clays yield Ammonites semicostatus, ete. 

Among the fossils from this zone possibly quite half of the very 
common species came from the Boulder Clay, though comparatively 
few of these show any signs of the fact, the ribbing, in the case of 
the ammonites, being extremely sharp. 

The following, among other characteristic fossils, were obtained :— 
Ammonites semrcostatus, Y. & B.; A. Sauzeanus, d’Orb.; A. Turneri, 
Sow.; A. Brooki, Sow.; and A. Bonnardzi, d’Orb. 


(0) Zone of Ammonites obtusus (figs. 1-2, pp. 66 & 70). 


Extending from J to a little beyond M (53 miles 48 chains to 
54 miles 10 chains), the lower part of the cutting exposed a mass of 
clay or shale which was especially unfossiliferous. An examination 
of an exposure 200 to 300 yards long yielded practically nothing 
that could be identified. As it was obyious that this mass of clay 


Vol. 55:] GREAT CENTRAL RAILWAY: RUGBY TO CATESBY. 69 


was above the semicostatus-zone and below the oaynotus-zone, there 
could be little doubt that it represented the obtusus-zone, though for 
a long time no direct evidence was forthcoming in support of the 
proposition. At the Hillmorton & Dunchurch Road bridge, between 
K and L, about 7 feet of this clay was exposed, but its total thick- 
ness may be estimated at about 20 feet (see fig. 1, p. 66). 

Now, although the main mass of the bed was so very uninteresting, 
the lower part of it made some amends as the cutting was deepened 
in a northerly direction, for towards the place where fossils of the 
semicostatus-zone occurred, and where blue Boulder Clay rested 
directly upon it, several fossils characteristic of the obtusus-zone 
were found. 

In the lower part of the Boulder Clay hereabouts there was a 
line of large blocks of blue limestone, which extended almost as a 
continuous bed for some distance on each side of the bridge at I, 
though the large blocks composing it were at very different angles 
with the horizon and each other, and many were smoothed and 
scratched. Some of these blocks immediately north of I, and 
nowhere else, contained enormous specimens of Ammonites obtusus, 
others A. semicostatus, A. Sauzeanus, Gryphea spp., Lima gigantea, 
etc.; and this is just about the place where the northward-dipping 
Boulder Clay would naturally truncate both the obtusus- and semi- 
costatus-zones (see fig. 1, p. 66). 

The following, among other characteristic fossils, were obtained :— 
Ammonites Birchui, Sow. ; A. obesulus, Blake ; A. lacunatus, Buckm. ; 
A. obtusus, Sow. ; and A. stellaris, Sow. 


(c) Zone of Ammonites oxynotus (figs. 1-2, pp. 66 & 70). 


The oaynotus-zone is exceedingly well developed, and was clearly 
exposed on either side of the line, both north and south of the 
Hillmorton & Dunchurch Road bridge, between 53 miles 55 chains 
and 54 miles 20 chains. There was no essential difference between 
the clay of this zone and that of the zone below, nor could any 
lithological boundary be made out, yet fossils become almost sud- 
denly quite numerous. Ammonites, belemnites, Gryphea cymbium, 
and Aippopodium ponderosum are very abundant. ‘The section near 
the bridge is approximately as below :— 


Feet 
Camel ore ete te io el a 8 
Zone of Ammonites arMmatus ......cecceceeeeee 5 
AGHA VORYMOGUS: | s,s dao acssnecd eat oaee oo 25 
ORCTOR: AL GOI ISTIS) 2. O's canvas poeeeemee uta 7 
45 


There is a nearly continuous band of limestone extending along 
the cutting in the midst of the oawynotus-zone, and at the same 
inclination ; it is very largely made up of Gryphoa (cymbium ?). 

The clay of this zone is blue, and by no means highly charged 
with iron-pyrites or iron-peroxide, as it appears to be in some 


Fig. 2. 


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Vol. 55.] GEOLOGY OF THE GREAT CENTRAL RAILWAY. (gs: 


other parts of the country. Nevertheless, many of the ammonites, 
and as a rule only the ammonites, have a thin yellow coating of iron- 
pyrites. Seme of the larger organisms are covered with Serpula, 
Anomia, etc., and others are much worn or decomposed, or pierced 
by boring-molluses. 

Most ef the fossils recorded from this zone were obtained from 
the banks of the cutting after they had been sloped, but a few of 
the interesting small specimens came from two or three heaps of 
clay near the bridge, the residue of trial-holes. 

The ammonites especially characteristic of this zone that I 
obtained were :—Ammonetes oxynotus, Quenst. (large and small); A. 
Guibalianus, d’Orb. (all small); A. Greenoughi, Sow. ; A. Simpson, 
Bean; A. globosus, Quenst.; A. trivialis, Simps.; A. polymorphus, 
Quenst. (not A. trivialis, Simps.) ; A. bifer, Quenst.; A. planicosta, 
Sow. (or between A. planicosta and A. bifer); A. raricostatus, Ziet. ; 
and A. tardecrescens, von Hauer. 


(d) Zone of Ammonites raricostatus. 


There can be no doubt, I think, that the zone of Ammonites 
ravricostatus occurs in the district with which: we are dealing, 
although it has not previously been recognized in the Midland 
Counties. 

At the top of the oaynotus-zone, near the Hillmorton & 
Dunchurch Road bridge, were found a number of. small ammonites 
very finely and distinctly ribbed. At first I thought that they were 
all the young of A. tardecrescens, of which species larger specimens 
were also found; but, on careful examination, it was seen that the 
sutures of some were much farther apart than the sutures of 
others ; those with widely-separated sutures I have referred to 
A. raricestatus. 

It was not: possible to separate this zone distinctly from the 
exynotus-zone delow ; it would also appear that it merges into the 
armatus-zone above (see list of fossils from the armatus-zone, p. 73). 
The fossils which I consider justify me in the identification of this 
zone are :— 


Ammonites raricostatus, Ziet. A. densinodus, Quenst. 

A. tardecrescens, von Hauer. Gryphea cymbium, Lam. 

A. nodotianus, d’Orb. Cardinia Listeri, Sow. 

A. subplanicosta, Oppel (carusensis, Hippopodium ponderosum, Sow. 
d’Orb.). Rhynchonella variabilis, Schl. 

A. trivialis, Simps. Spiriferina Walcotti, Sow. 


The part of the section within which A. raricostatus was found 
did net, I should think, exceed 3 or 4 feet (7 or 8 feet on a slope 
of 20°). Small nodules seemed to be especially numerous in this 
7 or 8 feet. 


(e) Zone of Ammonites armatus (figs. 1-2, pp. 66 & 70). 


The armatus-zone occupies the higher parts of the cutting 
immediately below the Drift-gravel where any is present, from just 
north of the Hillmorton & Dunchurch Road bridge to about N 


WARWICKSHIRE. 


NoRTHAMPTONSHIRE. 


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56 miles 


Volts 5. | GEOLOGY OF THE GREAT CENTRAL RAILWAY. 73 


in fig. 2, p. 70: that is, from about 53 miles 72 chains to 54 miles 
15 chains. There is a considerable difference between this zone 
and those below. ‘The clay is less homogeneous, and weathers to a 
lighter colour ; nodules are smaller and more numerous, and almost 
always of a reddish hue when they contain a fossil; in other cases 
they may be of the normal colour of the unweathered clay, though 
when broken across they are generally seen to have a peculiar con- 
centric colouring. Iron-pyrites is also very common, in small moss- 
like masses. 

Ammonites are abundant, but the great majority are small, and 
partially enclosed in nodules, only the outer rim, or a part of it, 
being seen; and, where not yellow from a coating of iron-pyrites, 
the specimens are reddened by its oxidation. 

Among other characteristic fossils I obtained :—Ammonites sub- 
planicosta, Oppel (A. carusensis, d’Orb.); A. densinodus, Quenst. 
(there may be several species or varieties here); A. muticus, d’Orb.; 
A. submuticus, Oppel; A. Guibalianus, d’Orb.; A. sprratissimus, 
Quenst. ; Pentacrinus tuberculatus, Mill. (very abundant) ; and Mont 
livaltia rugosa, Wright. 


(f) Beds between the armatus- and Jamesoni-zones 
(figs. 3-5, pp. 72, 74, & 76). 

About 2 miles south of the Hillmorton cutting, a little north of 
Willoughby, and extending for about 70 chains (56 miles 20 chains 
to 57 miles 10 chains) are some cuttings through a grey marly 
clay. The chief cutting is about 20 feet deep in its deepest part, 
at 56 miles 40 chains, and this is the only exposure that I have 
found to yield any fossils. 

The clay itself is extremely irregular in constitution and colour ; 
it is greenish in places, and very ferruginous in layers, more espe- 
cially the lower part; also it contains many hard argillo-calcareous 
nodules of very irregular or even fantastic shapes, quite different 
from such as are found in other parts of the Lower Lias of the 
neighbourhood. A few reddish ferruginous nodules of more regular 
form showed concretionary structure. The larger fossils were all 
yellowish, and in this respect readily distinguishable from those 
found in most of the other cuttings along the railway. 

So far as I know, these beds have yielded no ammonite what- 
ever, and there are no other distinctive fossils in them. Never- 
theless, there is scarcely a doubt that they lie between the true 
armatus- and Jamesoni-beds of the district; hence they are placed 
here by themselves. 

The fossils found were :— 


Belemnites sp. Pholadomya ambigua, Sow. (common). 
Pecten sp. (H. B. W.)* Rhynchonella sp. (H. B. W.) 
Gryphea cymbium, Lam. Waldheimia numismalis, Lam. 

Gr. cymbium, var. depressa, Phil. Montlivaltia mucronata, Dunc. 

Leda subovalis, Goldf. Coral? (A rather large spreading 
Plicatula spinosa, Sow. (H. B. W.) form.) 


' These initials indicate the fossils recorded from this locality by Mr. H. B. 
Woodward, Geol. Mag. 1897, p. 97. 


Fig. 4. 


WARWICKSHIRE. 


Warwick. NorrHants. 


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60 m> 


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Vol. 55.| GEOLOGY OF THE GREAT CENTRAL RAILWAY. 79 


There was a little Drift on the top of the chief cutting, yielding 
fossils: A. capricornus, for instance. 

At several places much farther south, but more particularly 
between 59 miles 60 chains and 60 miles 10 chains, east of Flecknoe, 
‘were found numerous fossils identical in condition with, though 
somewhat different in kind from those referred to above. I thought 
that they came from a thin mass of Boulder Clay overlying the 
Lower Lias, and probably they did; but, since all the specimens 
were so uniform in condition, it seemed likely that they had a near 
and definite source. Cardinia Lister was especially abundant, some 
of the slabs of stone indeed were almost made up of it; Phola- 
domya ambiqua was rather common, as it was also near Willoughby ; 
Hippopodiim ponderosum and Gryphea were also found. 

In my endeavour to trace a fault which occurs near here (60 miles 
9 chains, fig. 5, p. 76), I found an exposure of this Cardinia-bed 
in the bank of a brook a little east of the railway at 60 miles 
20 chains, and in such a position as to render it almost certain 
that it is at least below the middle part of the Jamesoni-beds of the 
district, and that it would be cut through in making the foun- 
dations of the bridge at about 60 miles 27 chains. 

The section was approximately as follows :— 


Feet. 

escitand ferruginouselay (no WDrift)) 2922: 22208) seewceec dak. 2 to 3 

2. Yellowish argillaceous limestone, shaly, inconstant, 1 
passing intomarl. Crowded with Cardinia in places... 


3. Light-coloured marly clay, with reddish streaks in it, and 5 
here and there roundish nodules ...............cceessseeees } 


It seems highly probable that these beds represent the strata met 
with north of Willoughby, their abnormal position here being due 
to the fault (see fig. 5, p. 76). 


(g) Zone of Ammonites pettos (middle Jamesoni-zone?). 


At the place where the fault occurs the cutting is some 20 feet 
deep, and the fault hades northward at an angle of about 15° 
(measured on the slope from the opposite bank). On the southern 
or downthrow side of this was an extremely interesting deposit, 
in several respects unlike any that I had found elsewhere, or seen 
described. 

For the reasons stated at the commencement of this paper, I was 
never able to examine the cutting itself well; but, as the very 
numerous nodules from it were unlike any found in other cuttings, 
and as the clay itself was equally unmistakable, I have found it 
possible to give a somewhat detailed account of the beds, though 
the material examined was mostly from embankments between 58 
miles 10 chains and 58 miles 55 chains; also between 58 miles 70 
chains and 59 miles 25 chains (see fig. 4). 

The dry clay is light blue, and abounds in Rhynchonella ; 
thousands were to be found on its washed surface, though they 
were nearly ‘all crushed flat. 


NortHAMPTONSHIRE. 


ep 
oe 
Fy 

2 

Lal 

| 

mM 

= 

Y 

re 

= 

a 

= 


wen -eenaennssennee-=------- Wolfhamcote Parish -------------------------->+<¢-- Upper Shuckburgh -- ><--------------------- Catesby Parish-------—-—-—- ——> 


N 
80 


70 


= about ) feet 


as) eee 
vey JOALY--454endh 
= ° 
Ay = i<o) 
“ik 8 
= 
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Loy 
Spug---- iS 
osplig---- Slo 
S 
Ss 
oO 
ise) 
aia 
2 
3 
& WPIIIS___..---- 
> 


10 CHAINS 20 


proy ory 


WBII}S --------- 
espug 
ANON Gess5s a ae a 
is) 
™ 
= 
= 
= YIo 
= = < 
S = 
= ~ 
S l 
= S 
3 Slo 
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o3piig = 
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o3plig -----~ =a S) 
S = 
~~ 


60 miles 


Vol. 55. | GEOLOGY OF THE GREAT CENTRAL RAILWAY. ra 


The nodules, although exceedingly abundant, are on the whole 
small, or of only moderate size, and mostly very smooth except for 
the fossils sticking out of them. They are light-coloured like the 
clay (never red as in the beds above), and in and upon some of these 
specimens of Rhynchonella were nearly as abundant as, and in better 
condition than, in the clay. Practically all the fossils recorded 
came from the nodules. 

No doubt these beds belong to what is usually known as the 
Jameésoni-zone ; but since there are apparently three very distinct 
deposits between the armatus-zone and the ztbex-zone, of which 
this is the middle one, and it does not yield A. Jamesoni, I have 
ventured to indicate it by the name of its characteristic ammonite, 
‘pettos-zone. The other specially characteristic fossils which I 
obtained were :—Ammonites striatus, Rein. (a small specimen on 
the same nodule with A. pettos); A. Oppeli, Schl.; and Amberleya 
- fidia, d’Orb. 

Besides the fossils, peculiar elongated—rod-like or branching— 
pieces of iron-pyrites were very abundant; there was also some 
specular iron in the nodules. Some of the nodules were bored. 


(h) Zone of Ammonites Jamesoni (Upper Part). 


Rather less than 1? mile south of the Willoughby cuttings, at 
58 miles 55 chains, immediately after crossing the Oxford Canal, a 
small cutting begins, and extends for about 12 chains (see fig. 4, p. 74). 
Its greatest depth is about 15 feet, and the material is a brownish 
clay with ferruginous nodules and much selenite, which appears 
to be absent in all the other sections. 

I found nothing here by which the zone could be identified, 
though since the next cutting southward is at a higher level, and 
consists of the ibe and Henley/-zones, one would naturally expect 
the beds to belong to the Jamesoni-zone. Mr. H. B. Woodward 
says ':—‘ Succeeding deposits comprise clays with ferruginous bands 
and selenite, with small, flat, ferruginous cement-stones. Crossing 
the Oxford Canal at Wolfhamcote these clays are found to yield 
Ammonites Jamesoni, Belemnites, Plicatula spinosa.’ 

The presence of Ammonites Jameson of course identifies the zone, 
and the great dissimilarity between the beds and those of the zone 
described in the foregoing section (g) of this paper affords an 
additional reason for giving the latter a distinctive name. 


(2) Zone of Ammonites ibex (fig. 4, p. 74). 


In the deep cutting east of Flecknoe and south-east of Nethercote, 
extending from 59 miles 25 chains to 59 miles 52 chains, there 
may be parts of three zones—ibew, Henleyt, and capricornus, though 
personally I deteeted only the two former. 

The cutting has a maximum depth of 40 feet, and when nearing 
completion, in the lowest part towards the southern end, and for 


? Geol. Mag. 1897, p. 98. 


78 MR, B. THOMPSON ON THE GEOLOGY or THE ~~ [ Feb. 1899, 


about 6 feet in depth only, I found Ammonites thew and A. Valdani 
fairly abundant, whereas no part of the slope higher up yielded 
any. Some of this material had recently been tipped between 
60 miles 52 chains and 61 miles 4 chains, and from this I obtained 
other fossils recorded as belonging to the zbex-zone. 

Mr. H. B. Woodward says ’:—‘ The late Prof. A. H. Green, who 
had previously examined the cuttings from Nethercote to Charwelton, 
sent to the Museum of Practical Geology a number of fossils which 
he had obtained from an excavation in the low ground south-east of 
Nethercote. These were identified by Mr. G. Sharman & Mr. H. T. 
Newton, as follows :— 


Ammonites Maugenestt, d’Orb. Lima Hermanni, V oltz. 
Belemnites. Ostrea. 

Avicula inequivalvis, Sow. Pecten equalis, Quenst. 
Cardinia concinna, Stutchb. P. equivalvis, Sow. 

C. Listeri, Sow. P. lunularis, Roem. 
Gryphea cymbium, Lam. Plicatula spinosa, Sow. 


The assemblage is interesting as indicative of the zone of Ammo- 
nites tbex, which is rarely to be recognized in this country.’ 

It may be noted that the ibew-zone has for a long time been well 
exposed at Braunston. 

It would thus appear that the ibev-zone is mostly below the 
cutting for the railway. 


(k) Zone of Ammonites Henleyi (figs. 4 & 5, pp. 74 & 76). 


A large portion of the cutting just described, above the lowest 
12 to 6 feet, according to the position north or south, in all 
probability belongs to the Henleyi-zone. It consists of a stiff blue 
clay not appreciably different from that of the zbew-zone below. 
Here and there were nodules, some very large, a few ferruginous or 
ochreous, and as a rule very unfossiliferous, like the clay. The 
only fossils found on the sloped bank, and these rather low down, 
were Ammonites striatus and Inoceramus ventricosus, but I did not 
examine the section well. A few other fossils were found where 
the material was tipped. 

The cutting from 59 miles 57 chains to the fault, 60 miles 9 chains 
(fig. 5, p. 76), is almost all Henleyi-zone, with the exception of a 
little Boulder Clay. The only fossils that I collected from here were 
two young specimens of Ammonites Henleyi, Sow. (=A. latecosta, 
Sow., according to Wright ”), showing remarkably well the gradual 
evolution of A. Henley: from a capricornus-like form. 

Another cutting, extending from 61 miles 30 chains to about 
61 miles 54 chains, appears to expose the Henleyi-zone. The upper 
part of this cutting is Boulder Clay and Drift| Sand-and-Gravel, 
but the lower consists of a light-blue clay with ironstone-concretions, 
and no fossils that I could discover ; it is therefore almost certainly 
not capricornus-zone, nor rbeax-zone. 


' Geol. Mag. 1897, p. 98. 
? «Lias Ammonites,’ Paleont. Soc. Monogr. (1878-1886) pp. 365-268. 


Vol. 55.] GREAT CENTRAL RAILWAY: RUGBY TO CATESBY. 79 


The whole of the fossils from what I consider to be the 
Henleyi-zone make a small list: the most characteristic being 
Ammonites Henleyi, Sow. (=A. latecosta, Sow.), and Inoceramus 
ventricosus, Sow. (numerous, and some very large). 


(2) Zone of Ammonites capricornus. 


The upper part of the deep cutting east of Flecknoe may, as 
stated on p. 77, possibly belong to the capricornus-zone; Mr. H. B. 
Woodward thinks that it does,’ and he obtained from it Inoceramus 
ventricosus, Modiola scalprum, Unicardium cardioides, and some 
gasteropoda. The depth was then (1895) 20 feet. From a general 
consideration of the dip of the beds and the inclination of the 
line, it would appear improbable that there can be much of the 
capricornus-zone present, unless it be through the influence of the 
fault a little farther south. 

In order to render the present paper a more complete record of 
the Lower Lias fauna of the district, I have included in the list 
of fossils at the end (p. 83) those obtained from the capricornus-zone 
at Catesby tunnel, farther south, quoted from Proc. Geol. Assoc. 
vol. xiv (1896) p. 428. 


III. Tae Guactat Deposits. 


The glacial deposits along that part of the Great Central Railway 
which we are here considering are very variable and interesting, 
and it is possible that some which differ from each other in 
appearance may be of contemporaneous formation. 


(i) The Blue Boulder Clay or Local Boulder Clay. 


In nearly all cases along this line of railway where Boulder Clay 
can be found resting upon undisturbed Lias, the lower portion of 
it, or the whole, as the case may be, if it is thin, is of the same 
colour as the rock below, and moreover contains the same fossils 
in about equal abundance. In fact, it consists almost entirely of 
the same kind of material as that found in the beds immediately 
below. The ice which disturbed these superficial Lias deposits left 
only a small number of erratics behind. 

This local Boulder Clay is first met with near H (53 miles 
27 chains) and extends to about J, say to 53 miles 50 chains (see 
fig. 1, p. 66). For some little distance north and south of the bridge 
at I it contains numerous, large, cubical Lower Lias limestone-blocks, 
so regular in occurrence as to look like a continuous bed when seen 
from a distance; a nearer inspection, however, shows that they are 
true boulders, for they are tilted at various angles, and they have 
rounded edges and scratched sides (see p. 69), also the blue clay 
for 2 or 3 feet below contains fragments of chalk, flints, quartz and 
quartzite-pebbles, etc., mixed with the Lower Lias fossils. 


1 Geol. Mag. 1897, p. 98. 


80 MR. B. THOMPSON ON THE GHOLOGY OF THE ___ [{ Feb. 1899, 


The large nodules are found in diminishing numbers at about the 
junction of the blue clay with the brown Boulder Clay, rising with 
the latter, to about 53 miles 56 chains: that is, to the point where 
the Boulder Clay ceases entirely. 

In connexion with this I may again refer to a description of 
some Drift-beds near Woodford, south of the 67th mile.! I decided 
to examine these again, in the light of the conditions more critically 
investigated near Rugby. Between Rand S (op. cit. pl. xiv), the 
Great Central Railway branches, one part continuing the main 
line, and the other forming a connexion with the East & West 
Junction Railway. In the branch-cutting nearly the whole section 
appears to be undisturbed Upper Lias: east of this, on the main 
line, however, and only a short distance away, where a bridge 
crosses it, the following section is seen :— 

Feet. 
1. Soil, witha dittleserayel <1. tens ucconeencse eee eeene eee ee 
2. Mixture of sand and clay; very red, looking at a distance abouelo 
as though almost a sandstone; blue clay observed, which 
on a closer inspection is seen to contain a varietv of stones 
3, Blue clay with numerous Upper Lias fossils, Leda ovwm 
being especially abundant. A close inspection shows that 15 
it also contains pieces of red sandstone (Northampton 
Sand ?), chalk, pebbles, ete...... “ss Sra Siawinal i eined a See eee 
4. Upper Lias Clay, real undisturbed blue clay showing a 3 to 4 
ierecular junction WathNO. od an. <sceccaseseeteecaeenes saceene eee 


Where No. 3 joins on to No. 4 it can be noticed that the former 
is distinctly of a browner tinge. It appears to me that No. 2 
represents the brown Boulder Clay, and No. 3 the blue local 
Boulder Clay of Rugby. 


(ii) Brown and grey contorted Boulder Clay. 
(Lower Boulder Clay.) 


In some places resting on the Lower Lias, in some on the blue 
Boulder Clay, and elsewhere on an intermediate sandy or chalky 
layer, and always below the gravel-beds, there was found near 
Rugby a brown or grey Boulder Clay or Loam. The colour varied 
much, according to whether it was wet or dry, as also did its physical 
characters. When wet it mostly looked like and cut like.a stiff 
clay, in mass; but really it was most irregular in composition, 
ranging from a tolerably pure clay through loam to nearly pure 
sand. Very considerable portions of the mass consisted of an 
irregular mixture of sand and clay, the sandy layers being sandwiched 
in with the clay, and these parts, without exception, seemed to be 
highly contorted, the contortions being beautifully shown when the 
material was half dry, owing to the different hygroscopic capacities 
of the sand and clay. A better idea of this deposit will be gained, 
probably, from the following reproduction of my notes made on 
various occasions in 1897, 


1 See Proc, Geol. Assoc, vol. xiv (1896) p. 427, 


Volk: 55: | GREAT CENTRAL RAILWAY : RUGBY TO CATESBY. 81 


D to E(fig. 1, p. 66). Brown and bluish clay, irregular junction 
with the gravel, not a trace of afossil. A few small lumps of chalk 
occur here and there, and a few pebbles near the point where the clay 
joins the gravel. Thickness 4 to 8 feet. 

E to F. Upper part inclining to brown ; lower part, where deep, 
bluish-grey when wet, very light-coloured when dry, similar in 
colour to the micaceous loams of the Middle Lias at Catesby, but 
contains no mica. Not a single fossil, but at one place where a 
stream of water had been running (from it?) were found a few 
pebbles, angular fragments of flint, and numerous well-rounded 
chalk-fragments. 

F to H. Brown to grey or bluish-grey, colour depending upon 
the variation in proportions of sand and clay, and wetness. Highly 
contorted, plastic when wet; rubbed with a toothbrush when dry, 
it leaves an irregular corrugated surface due to the sandwiching of 
clay and sand (more sandy than nearer Rugby ?). . Not one fossil 
seen, and scarcely a trace of chalk." 


Gi) Chalky Lower Boulder Clay. 


At about 53 miles 27 chains (fig. 1, p. 66) there is a sudden 
change in the contorted Boulder Clay. While north of this point 
the clay is remarkably free from all inclusions, south of it the clay 
is extremely chalky, so much so that it looked almost white when 
seen from the opposite side of the line. On the western side of the 
railway the two clays were sharply separated, by an inclined wedge 
of sand yielding a considerable amount of water. On the eastern 
side the sand was not present, but still the junction between the 
two Boulder Clays could be seen to be inclined at somewhat the 
same angle, although the junction was not so sharp. Between this 
place and where it thins out towards I, the clay is very streaky, and 
there are elongated and twisted patches of gravel in it, containing 
Gryphea and other fossils ranging up to the Oolites, and a good 
variety of pebbles. These inclusions make it porous enough to yield 
water. 

The Boulder Clay which extends from about 53 miles 45 chains to 
53 miles 58 chains, although regaining very much the brown 
coloration of the main mass farther north, still contains a large 
amount of chalk. At 53 miles 51 chains, for instance, it was very 
white-looking, and sandy layers in it yielded water. At 53 miles 
43 chains the bed is particularly sandy, and of a good red colour. 


1 There can be no doubt that this brown contorted Boulder Clay is of 
contemporary age and continuous with the extensive sand-beds of Hillmorton. 
These reach a depth of 170 feet not far from the highly-inclined bank of 
Lower Lias clay, against which the upper part may be seen to rest. This 
matter is briefly discussed in the Report of an Excursion of the Geologists’ 
Association to Rugby in May 1898 ; see Proc. Geol. Assoc. vol. xv (1898) p. 430, 


QJ. GS. No. 217, & 


82 MR. B. THOMPSON ON THE GEOLOGY OF THE [ Feb. 1899, 


(iv) Sands and Gravels (Mid-Glacial). 


The gravel-beds on this railway in the neighbourhood of Rugby 
are a part of the great plateaux of sand and gravel upon which 
Rugby stands. The maximum thickness is about 25 feet, but, as 
will be seen from the section of the line, the thickness varies 
greatly, owing more to the irregularity of the junction of the sand- 
and-gravel with the underlying Boulder Clay or other beds than to 
a difference in level of the ground. 

Commencing at the beginning of the cutting, at D, 52 miles 
AO chains (fig. 1, p. 66), the gravel terminates on the top of the 
steep bank of the Hillmorton cutting, overlooking the Lower Lias 
valley to the south at M, 54 miles 7 chains (fig. 2, p. 70). 

The gravel does not differ much in composition from D to I; it is 
very irregularly bedded, rather coarse and dirty, of a reddish colour, 
and sandy in places. From I to M it seems rather cleaner and 
of a richer red, and between K and L more sandy and coherent. 

I found no fossils whatever in this gravel, though it is true that 
I did not devote very close attention to it. It contained much 
chalk in small pieces; flint, mostly rather angular ; and numerous 
well-rolled pebbles of quartzite, quartz, gritstone, etc. It will be 
noticed that, at about 53 miles 42 chains, the Boulder Clays are cut 
through from top to bottom by a pocket of the gravel (fig. 1, p. 66). 


For the next 7 miles there is, on the whole, a singular absence 
of Drift of any kind, at least in quantity deserving of particular 
record. A thin capping to the cuttings between 56 miles 20 chains 
and 57 miles (fig. 3, p. 72) yielded: Ammonites capricornus, 
Grypheea, limestone, quartz, and pebbles of various kinds. 

In the cutting, between 61 miles 30 chains and 61 miles 53 chains 
(fig. 5, p. 76), there are some sands and gravels interposed between 
a red Boulder Clay and the Lower Lias Clay. The deposit is very 
complicated, consisting of a red breccia or conglomerate with some 
ironstone-fragments not much rounded, fine sand varying in colour, 
and whitish layers of calcareous matter, all much intermingled, 
varying in thickness up to 5 feet or more. A distinct white layer 
of calcareous matter is interposed between the conglomerate and 
the red marl above it. 


(v) Red Boulder Clay (Upper Boulder Clay). 


The cutting in the parish of Catesby mentioned in the foregoing 
paragraph has, resting on the sands and gravels, a mass of red 
Boulder Marl; it is of a red different from that of the gravels, and 
contains green inclusions; indeed everything points to its direct 
derivation from the New Red Marl. No doubt it represents in 
time the Upper Chalky Boulder Clay of other parts of the railway 
farther south. In thickness it varies up to 10 feet. No actual 
boulders were found in this marl; it breaks into roughly cubical 
blocks on drying, and falls were rather frequent. 


Vol. 55.] GREAT CENTRAL RAILWAY: RUGBY TO CATESBY. 83 


IY. Last or Fossrzs. 


[In the following table, A. stands for abundant, V.A. for very abundant, 
R. for rare, and V.R. for very rare. | 


ES ag g 
N f ; Sel eieeie les aS 
ame of Species. = 3\ S/S 5-8 |as ‘s | $ 
2.8) 21S e818 3). 24s 
S8)S SEY AS|S PRLS 
Ammonites (Arietites) semicostatus, Y. & B. ...|V.A. 
Peet) LU TMCTE, SOWs  svaivses--aeneeaosecssecers- A. 
EMME OOKI, SOW. .ccpesteecceveessssvcecsce ss Ax. 
eaten) Bonnardd, @ Ord, .2:....0-... 0010.08.08. R. 
cae) Sauzeanus, MOrDd. ........0.00.02.0080- esl Mond? 
BEAD) OUCUSUS, SOW. inten ie nsdscuacectes eosacieaie sits po ple 
PEE T) SLEDIGTIS SOW «, 2 acciseaiscweeosseedasnecess anc) | 2B 
A, (Ar.) obesulus, Tate & Blake ...............06 aoe he 
aeaeAigoceras) Birehit, SOW. ....00..s0csceseeesee wah oals 
Pane) ticuwarus; Buckm.  ... sc.ceiescesesers sete fede 
eee.) PULNECOSLD, SOW «. op o- <0 0+ vans oeiseansddexe wee |Meat Ab. dy Ee 
A. (Z:.) subplanicosta, Oppel .............+2s00-++ rasa aeeeeelie eee. 1A 
Dame Ofer, GCSE... ...-.06.sn000secndseneeedde ee Be 6 Be ee 
A. (Z1.) polymorphus, Quenst.  ...,......2eseeee Bo Va 
Rene.) curvicornis, Schl: 2.22. scr0scassancese- . |V.R 
eee) (Pauli, Dumort.?)  ........2.210000s056- . |V.B 
A. (Amaltheus) oxynotus, Quenst. .............45 2 gee 
Hae(-A071.) Globosus, QUENSL., ....0000e..0seesecceeee- R. 
A. (Am.) Simpsoni, Bean ......... eek dtmadcacasd ott 
A, (Am.) Greenoughi, Sow. .....sssccevecceeeees ae ee 
A. (Am.) Guibalianus, VOrb.  .........eceeee-- rh ee Cy Se 
Peri.) rvialis, SUUPS.  ...-.-+--.--.sesecesseee A. |V_R. 
A, (Arietites) raricostatus, Ziet. ..........0ccc0c0s 5 slice 
A, (Ar.) tardecrescens, Von Hauer............... eh Ae 
mentear.) Nodotianus, Cd OLd. .....s00cee--2escasesse0 . |V.R 
mia@ar.\mpendens, V. & Be... ccccccossceccasess wae | vee | Viadkbe 
A. (Ar.) spiratissimus, Quenst. ..........0...000: east Iwtaet 1a less ahead 
A, (Aigoceras) armatus, Sow.? ....2...ceceeceeee wise |) snes fy oct lf Visca 
A ( A.) densinodus, Quenst. ...4:.....s0+--+05004 one |. casaivt nme Ae 
Es) URCUISDINA, SOW. — vasecosnenanssssencsaces sities Pore dapeee tee 
Pa tT) MOULICIUS, A OLD.. ..2.02 «iesnewe ans oes cacee oe: dae [evotre if» eon OE. 
a(eee.) subinuticus, Oppel ...2.c.0.0560.césees- vee [one | vee [VER. 
ame.) Peri0s, QUCHBL... 00.0. s.ciecceensesenese se: oan fly citer >|» BROAN me coet pel 
EM) IGMLCSONZ, SOW. .2-.2s0000. careetensseeee: R. 
pene) (Gumprechti, Schl.?)  .......0c00000s00- V.R. 
BMPS SIGLUS, REIN,  .2.01+<nsc0mecd aditerccece- R. | A. | BR. 
A. (Amaltheus) Oppeli, Schl. .........cccc000ece0e V.R. 
J N78 0 TOYS Cs oc Pe 
A. (Phylloceras) Loscombi, Sow.  .es.e.eee.ceeee R. R. 
A. (Lytoceras) fimbriatus, Sow. .........0.20000s R. R. 
A. (Aigoceras) Maugenesti, VOrb. ..........0..4. R. 
PMD EPCH EL SOW. .icesclesaéanvess ceeds Jeecses R. 
SCG OR 6d re ee re ad ee 
A, (Z1.) Henleyi, Sow.= R 
A. (41.) latecosta, Sow. | ee ey bt} DOS Le wile coe dd ° 
EE POE AEG ood oval snc sonccedue xe b- 9} Gp 164 LO | Sep Tepe Bed 
3 | 


84 MR. B. THOMPSON ON THE GEOLOGY of THE [ Feb. 1899, 


List oF Fossrts (continued). 


ete Ee 
SES es ee ee S 
Name of Species. ‘esl 6 [SS] 8 isk oe le 
Ss/2i£¢| 8 132). hea 
SS|S [PE] SSS) § | 81 & 
SslS SES S/S | RIS 
Brought forward ........... Die ae eteacia D9.) 6 P16 | 10) o |. 7 Tee 
Ammonites (Atgoceras) capricornus, Schl. ...... ihe ae VAG 
WEXCUCIRMILES ACULUS, ITIL, > ch deewicce samendeabucesnanese VAR.| cou Weel Vedio ane 
B. Cnjpunoroulcm, PW Py. .cchesnecsecctrs taeeme bossy slic el eee 
BD. (Pen CTH aUUS, SOWL2) lien scsbseeer te eocs. eal toeenal ree gil anew 
B. Orem porinis,: VW Ota 8) Bien betes seas ences patito) ZA gee a aoe 
B. (apicicurvatius, Blainy.'?)) ws..tes totes eomeors onay | base. eae GV AA Sache wine 
IB. OPES: WANING 4.0 eons hain Reece Keakeee iho til cased wee cae 
B. potler, SIMs.) <ae.ccsce shan: Bot See ee som ch gene dh entins ots ise IRE 
IB ClAMALIS, SATU Va le Occores cee cere wee ck eae kee 8s ane, Puen Ieee eee Ae ape A. 
Bs GAT OSUOLUS, TEALEMUL NY eseseecopesnies eer c east R A. 
BS. gene | Mela sheet Db: cern Bale Oe ear ee eee | ieee A. 
INGULTISSULIGUUS, SOW sceacisucbern ganect ss cnwse eke TFS oes call neat 
ISUAG Scho Sh eRamiaees, ALIGN NM Jiao pe Sean meee aA ah R. 
ACICONUMGIBION, Echesoa- tee cemr heer e waters sicenipe tie. R. 
A. Margimata, SMIPS."..9.).Bast-pasebaee she eeeas ae Leal Mee Wome A, 
Acteéon oxynott, Wilson, MB. .........0.0+es0+000 Selick hl BAS 
Amberleya elegans, Miimst. wo. f...oncacasneeseeenes R. 
A, Chapuist, Torq, do Piette! 2... sie. sc6c.s-me<op eal ene Wee 
GE Co on ce nine Ye oney Se encase Palau ee tuce nic al cezecal cles 
A.\( Droctnis) fidid. 0 Orb. oe .n..cereeasnue sone Cotoyl 227 all came] see eae 
A. GID TECALIS, DOW) ae bee vaneaes histae cates veers ns Res = eee a ieee A. 
COPULTUUIOSD. Taian 3 Seat scien s cedieue sad vane desea R. 
Chemnitzia Berthaudi, Dum. «.....0....10.000+00 R. 
OD \SQUTHEGLG:, UAE cero eickee Ben decane cies Sones ana R. A. 
Ch. (aranspersa, Make? tec oe atcsise ates cmenmanens Li ee ss =] geass 
CHAS? Sec doa name aaehescn nee Beceasie cetacean sale Rs | eR. 
Chia Siesst AS tollin): Sicteh kareot escae te teehee Be. Niko adkee 
Oh KaNcolnd. UAL yee ae e Nch ect wetetees -eeeEce ca Aw | RB, 
Crypienia solarioides, SOW. | .......+.s1s0+see0s A Micon al debe 
Om rareiieroriis, Dum, Ve iencasgencne nt ees anencuise wos cao; High en ttl eet Nee 
COMPOSE: SOW. Shih: debussiwaneterctsseeeeeeanen os. Rbidieaal see ss 4] CoRR Una R. 
ierrnelia wuprerd, Tere | ai Weewed «swank se eeeet- Vea. a R. 
Bl tien a itl stab ieie~ nics os olebiaid nivis atop serch oineebp aia vin Ch eeey | te Al seseetial: Aas 
Cylindrites Whitfieldi, Moore ..0...0:0.-.2-0000 see, | VisdRicl civ sie ml Voting 
Phasianella (Bourguetia) Morencyana, Piette . VR. 
Pleurotomaria anglica, Sow. .......sscse-sseeeee- be R. 
BEE SRN MRC ES ARO RE eich ME ins Pawenuche Sackccnks R. 
Trochus Thetis, Minst. (or near to) ............ a ete ees. 
Bourguetia turbinata, Stoll _......s0-rose0-0cos- Lids. A oes ee al gabege All eee al eee 
Dentalium etalense, Terg. & Piette ............ <u it deine AN 
DD MUU, nate oniecisc tebe singe sinates neces was, | sone dll ee 
D. (CHONGGIUT, NUGEESD) deccscvnvesseesesasese conse ra Af acct ee aioe dla ae 
Asiarte Oppel WVOOre. (i. ce.msccerens deca seb snes Aa seas : 
A, obsoleta TOME, eieciede nas 0 Te Oh ed aa ae icy, A S's ae 
A, GFT a disc ove buc muni enees sete anS Ui dee Gopehei eae a A) est cia etal ante Wo te 
LAF COULD Spe weattrees 0 tesa basin tdetiass a nian cea Pelach Sra he! pe gas | 
A, LONG tC, TRO. f.losteeemenaernleans eva rsss's sieve SORy | hee cl eeendl ewan Vea 
A, "(Concinng SLA) Acetate tke ache» Doles me. inize bs ll ele caller cee 
Carried Tomyard | Py vsaensteorkaeeaenevenste 18; 8 | 38) 14/17) 9 ) Ze 


Vol. 55.] GREAT CENTRAL RAILWAY: RUGBY TO CATESBY. 85 


List oF Fossrts (continued). 


ae} E 3 
g S S g S 
Name of Species. 2 el ae Shs as a = 
SB) 8 |S 3/8 les =| 8 
2S] << |S SS Ss a» ess = 
28/8 |@§)§ BSS |S |S 
S 
HS(OS Ss SN AS Ss |e ]S 
ROUBHGHOLWAEG (22...) veel sile cesses 18.) Sa) PA ea Gklk 2° | Ls 
Anomia (alpina, Winkler ?)  .......s..sesceseenes secon flo wera alia 
PPE SUTURE, OCA) oodden cede ss ss scacesaevecenees Bee Men \ sl is 
EEN anna wok eo tacavan-dasagdcewbese¥s ne Sool Paton tits ae | oe ae 
PA TIEHUSTIOOLIS. GUONSE. 52. ..cccseaeocecccncerceee Le ACI oes hse Ree A. 
Avicula inequivalvis, SOW. ......s0s.ses0cecseeeees See Tse 16 5 Ae Ay V.A. 
PBBGHIILIDCSS Now Oi To. | glpeian cide 7eideceanass tee eeet 1 Dip as R. 
Pele) SEN ICKIGMOL, “LAGE. 10 y/.56<deeensses0ddeacsece% . A. 
PARCIPUGOLG, AIMCKID |) 2.082... seccscocessenten nails vas 7A, 
hn BUDS My aS oe Oe eR ne R. 
Gait LASCETL, SOW. 520 dccsacdccs dencnvedss coders. wok fsctow | hOAGe ibe een hee 
Calisiert, var. lyortda, SOW. 2.<..+..<0s<0s-+-0+s RS pce, |e Rees 
ME MCMINEIEds POEs) ie oa aeet ceiciaeg z da nSecs caste seeds 8. Wd. Ne 
CRrCUTIC, SEMEN: 2. 2212, 2.<cae<ccweceacsesees ses : AS Weal, 
CE MCATCILUG SEULCNDS 3.2 os cas scecxsubageves sees a wats eckwe 
Cardia MaStana, NOOTE JJ..cc.cc0ssreesscsessesess V.R. A 
CEHICICOSCULO SETI 5.8. ..3s5cae nen ate Sener A Dis A 
CE ACOUSUUNISS WAGE, -52..de<\cancceddvescectecsecscaces Jebel spay Mee 
OMeuee Mipsterd, Zits) \ scdédnaesesecsnsccs vss Bical ce a eae 
AC PSUGIGIL JCUMCUBE: 0) sccecetcaescoensseeanaceces cnet tb tN 
Cypricardia cucullata, Miinst. ...............06. Jchlbccoe lt aoe ue i) Verne 
Gervillia (Hagenovi, Dunk. ?)  ...........-000ss. R. 
Ge (uetacaicis, Quenst, 2) 2. ....s<cccsesesccecseeeess wigs Wteaae of) Waawe 
ICES, MC KMNU) Y .. cisesessoddesenonsasavenccese siccg.alle Saeed ators [ia scenes 
SEES YD MG CLOLCO ONO, | oi cesendccwaerivedeatneasnt R. 
Gryphea cymbium, Lam.  .........sesneceeeceeees Ace fe Sera |Get Wea INT ASV) oes 
Gr. cymbium, var. depressa, Phill. ............ ‘och <A Lape aa tee eae | Aen? Ale lio, "Ae 
Gr. cymbium, var. obliquata, Sow. ..........06-+- eas: Riven Weve |e eeen PAS 
Ee CUMLU IAIN 22 Sse aed dads aves dsawnseces Lands ly sy Ee V.R. 
Goniomya heteroplewra, Ag. .....e.eececeeceeeeee Ps R. 
RUC, WIM E ond eee oie Seninte sacra nd ces ses R. 
ISDS ICH OY CORBI ge DV 0 es oat ee en ee so Vee seevily ches 
Hippopodium ponderosum, Sow. — .........seeees ogi (Voth MG Rel eg ee... Wee R. 
Inoceramus (pinneformis, Dunk.?)  ............ shells & cual ese 
EUG UCOSUS SOW «5 cicin was dweice. chk ad wAeicie dviveeinrcieie cre ett Ales fo Ata iW Amen EG 
WE SUUSURCOUUS, IWLMMISER, | ©. etd cones adedstu.cr siere'eraeeee BiesAG b AR i ALuINe. Bi. 
wc Biba ley per LAR AS oh Ree SS sy leer a ae R. 
PUB PIG ANLEL, SOW os 3.5 4ace weenie ouicdeekiecexeceds WAS A: | BR: 
WR PCCHIOULES SOW «: 255 asc ced ~) ace rdactothiel oaws'e soe R. A 
ES PUUCSOLE SOW a) © ocsse ead dgsssadsetlead sv ae-ness Bix | cases |) Ste 
Jie SUEDE te TA Oe Oe eee ee oe tact | canna eee 
ACT RULIVI NOWL 255k 5 oop sa ce ee ucs acnniee vane Jace FSSA meee Psst Ee 
a Bieharis: GORD. 2) 4 obec scp ecetenecne nace. Jose's i ae) | Male: 
NEEM AEULICOSEA MIMMISL es | stent ccosicine des dcinwavens Re} PAIRS. [We Ae . |V.A 
DA uond. DwmOrts?)! saachcac8eacaaceexcs eck visi |ib atebapl tole seh Wane 
Lucina limbata, Terg. & Piette. .............0000 A. 
doy Bip Tste SUR ea Nai RC a cach nae 
EMP ROTEVIETT, MODE OF ci ee nas tacddeecicietacn waco coal} Ale Aer Ie 
DE CALCU C OTS | ncn idhe ae dale MWe ec ehewenidenes Bap te ee AS 


a | | | | | | 


Gireried MOE WATE) The vesetegsites een sice senses 29.1 .L1.), 66 |t22e(1a8: 18: )) 4 | 28 


[ Feb. 1899, 


86 MR. B. THOMPSON ON THE GEOLOGY OF THE 
List or Fosstts (continued). 
= t 
TH w as a 
N f Speci a 3 : 2 $ le is s 
ame of Species. e2S| ¢ $8 8 188 | 8s 
Ss) 8/88) sig? | S12 
IS §| 3 \@§| = B§i § | 8 | 
R8S PsN SIR | RIS 
ipromemt horward) | Ae... Rent. eke tecicesene 29 | 11 | 66 | 22 | 338| 18 | 4 } 28 
DE UINOT. SUN DE. 5. «doth e tern nda dense fovdnees ee He Asoil cee A. 
WasVooaalés. Coldi. i.cdthe Ree dea ee es A. | AG ae 
RONSON E EP tok. Heine 4 one ee akpere eae Orval Mae bs R. R. 
Ry sgmapiicd, Waite! ii. .nsces tener teeatedege salves ae ; es. A. 
MM eddoldn leurs, MSOww: 2) | Ws. haewateseh cet seketesecs A. 
M. Hillanoides, Chap. & Dew. ..........00.0008 2 V.R. 
IM: (aumismadlis; Oppel 2). besciteeiccessctsasdes i; Boe it eka es 
ET SCHIST UME PS OW 4. quate ped MAE Ne see eGR eas as, | Bo) Awl) Aes Ae 
Macrodon (intermedius, Simps.?) ............06 a A. -os | evel gee 
Myoconcha oxynoti, Quenst, .....-...secessesee: ; V.R. 
Nicula variabilis, Qutenst.  cicccccessckbedescss-ce- a. A, 
Ostrea ungula, Minst. (and other forms?) ...| .. A. 
O:\(Goldifiisst, Brown ?)) sscctssencctesscsdesseceee: i: Te.) sehen oie 
QO) Gus pantie fersceot- aceon teste eis aecdead as: sive R. | cea) voc} Rae 
Peetenicgualis, Guenst.) .Aacdewacmedance decks csans R. wes cwere i]! Asse SoS 
IP’ Warraarbarpisy MGR sce wi Bues 8 Sacks oR hoa ds A A. | Ri | A. | Wega Views 
PP MpPgsSGUSNelull. © ie Oe. Mees bircctaeaehs SEO As |... kynalt "tea ame 
PLODLOROUS, SC MMih ee Moke yt an Cae ie My ce R. 
P. \acuboradidtits, Winst. 8. caeeke 6 iesd och ccs cs Pe aa R. 
IP AGTISCGLEN WUUNTINE Binten cee deg hese. eae ee ote R. 
PB (CGUCUMOISP SOW: nes She Beco ne ntsbbledsasact ees re A. | Ay dena 
Pholadomya ambigua, SOW.  .....csseseceecaeceee| coe R. A. |ossc | Mey) ae 
SPEEDY. Bi soe Beek ais wc By cariscka seee abet outa ves R. 
Pe BEUTIGHTE SEM ic A sceh absinthe nwntea ts vase ate PS eres ast R. 
IE VCO CUMONSIN Puts A bicbiad Bctedbsoob bs tino kieoSaisde nes oe - » | VeR: 
PU; SDINOSI SOW. estes shed ee Saved ile Cage cet ee R. | R. |V.A.| Aa A. 
IPT, sarcinulas Wigaiist tx ecg eacasee iv eetes oa ae ee R. 
Pleuromya (siriatila, Ag. ?) ccseccerseesssessocen| eee A. 
EU ICOSLOLG Ne OLED. Vacs dues cunt eucees otk Rie ae on ft | Wedel Anil ts A. 
Protocardium oaxynoti, Quenst. ..........cceeceee| coe As 
PEARS ECHR IDR. IONE» 4... Wen be bidia en Soa RG eee - sep | deeeel Ree R. 
inmaeolanne, No ®t 33, i, bi dks Oeheash feuekieess tad ansiitease ll wile pele 
MSN Bete eda ree wSedethe A tccarseeceeecseeueeace Sisk oe] cin | caer | 0s 
CR ODN Me ces Pais ox nis gua ober cueiaee nee teem eeaeee re won, sa (use eee 
Unicardium cardioides, Phill. ...............000- R. R.'| Ag Vases A. 
MOT ULOMS PPD vials ceo x ele odensuc-bxduekanebebataesteeceh UR, 
Rhynchonella calcicosta, Quenst.  ...........008- A. Be A. 
dD MOD TEAUOLS SCs, oy cabs is cavese cath. beassosck. VWeAs Vie; 
Bh (rimnosd, woulbuch ?),)) 80.026. Besiaseces cde V.R. 
TMA) eames Meee ee te epoca <iais cee ans «Ub byes cg aks sie R. 
Spiriferint: Walcotti, Sow:: ......0c.e00csseecsese0s : VA, 
Sp. -Waleottis, WAR, WOEG, SOW. sense sascctessdveoes oe R. 
Waldheimia numismalis, Lam. .............000.- a & A. 
W, Per forme, VAWR. | Je ccaiciks diem dtcsawebicessete. ape | R, 
W. (Daewina, MADesh. 2B) ties caansdentshesesies sa R. 
Lerebratula punctaid, SOW. ~ yesnccepeoesescraeaes ie sey BS R. 
DP. (pstlonel2 VQ Wenge) cir ese dts tcteupetssucwe ess i V.R. 
Crustacea) cs nc. can tee basmcateeeecos ots baeeeaen V.R. R. 
Catriel forward’ Gbk.t. dah. dates cueesas cee 33 | 11 | 94 | 28 | 56 | 28 | 10 | 43 


Vol.55.] | GREAT CENTRAL RAILWAY: RUGBY TO CATESBY. 


List or Fossits (continued). 


87 


ee : 
vame of Species. Sites! Sas ets 
SUS SS ee SS ee 
aT emlaty LOR WAT soo cp 2. cn nceddnce- sos s<tes 33 | 11 | 94 } 28 ; 56 | 28; 10 | 40 
arom. (LEVIS PARE PY) cen ineosennonnadeeeneseaet sis) fee aH racial ciate | V okt: 
Bairdia liassica, Brodie .............0.seeseeeeeeee my iP fs hea | Re A. 
Ditrupa (capitata, PWill.?)  .....2....002-e0ee eee V.R. 
Weerecoucin Witte A 0. Pees Soe ieee. is AY Ae 
D. quinquesulcata, Miinst. ...........22...eee eee A. 
Mpmerala sts: Pictba: . cpccidsc, wucurlececevesdieeteenie- os es ls 
Po ee ie, Be EER ele eee eeseh | cece Weenie 
Cidaris (Hdwardsi, Wright?) ............0-.00s |V.R. | 
EL SUD yells MORSE SD Rs Recaro ee PSL AE TE aaa ieee eae | ae (Ete 
Pentacrinus tuberculatus, Mill. ...........0..265- ieith te) pa! 
SCAM SINT ONDE Ys dash onions «dai ion sseecseeenes sapi-ouact |. =eeeliecete lL ASE i coe ec ke ates 
ere are Re on e| — conk | = ay ficacmagl ek 
Extracrinus subangularis, Mill. ............22226.| + : A. 
oe EEL ET OT A SEAS lll coe a ty ae A. 
ILD TUROLLLA TOTS OR) Aa an ee [ies V.R. 
| SUMEROEW MOSIE ANN ITAC IMG cB susapcie.anle tds daa -opsisiees. A. 
NE cp tay OTe, DUC. esd ctncnensevtcavecsatassen- Wes? A. 
Samal. beh ieee he Selanne aia mr ennan ee 22 Seal Wiclise 
Stomatopora (antiqua, Terqg. & Piette?) ...... -s« |V.R. 
ISIC OGUE Doo aesgcswisuads0hsdack seaisde tack wae Sa leaes a 
| OR ATCRIGTLO IS). od aisiaaiablne ann sender sane oeieanses' A. 
| Dentalind sp. vevevceveecevree vec eetieeeeise A. 
| Total number of species and varieties ...... ao | Pies Gore 162 28:7 11 | 52 


Discussion. 


Mr. H. B. Woopwarp remarked that the Author had added 
largely to the information obtained by Mr. Fox-Strangways and 
himself. The recognition of the zone of Ammonites ibex was 


interesting, as it had so rarely been identified elsewhere in 


England; but it may be admitted that the non-discovery of 
particular fossils is no proof of the absence of any zone, or 
of the non-representation of any hemera. 

Referring to the occurrence of certain limestone-nodules of 
fantastic shapes in the armatus-beds, he suggested that they 
had been formed in sediment which had been slowly deposited 
and wherein segregation was comparatively free, whereas the 
smooth lenticular nodules found in a succeeding mass of clays 
might have been formed under slightly greater pressure in sediment 
which had been more rapidly accumulated. 

The Boulder Clay which he had seen in the cuttings south of 
Willoughby belonged in every case to the main Chalky Boulder Clay. 

The Rev. J. F. Brake remarked on the interest of this paper, as 
showing the development of the Lias midway between the north 


88 GEOLOGY OF THE GREAT CENTRAL RAILWAY. _[ Feb. 1899, 


and south of its range. The Author’s results showed that it was 
much more like the Lias as seen in Yorkshire than as seen at 
Cheltenham. He also drew attention to the collections of small 
ammonites referred to by the Author as occurring on certain 
horizons: such collections were not always on the same horizons, 
or of the same species. They were the fry of larger ammonites, 
known or unknown, and were scarcely worthy of a name. Speaking 
generally, he did not think that one in ten of all the ammonites 
that had ever been collected anywhere were full-grown. 

Mr. A. E. Satter said that four distinct Boulder Clays are 
mentioned, all of which seem to be characterized by the absence of 
boulders. In recently traversing the district covered by the paper, 
he had been struck by the different character of the Drift-deposits 
as regarded their relation to older drifts, their contained erratics, 
and their height above Ordnance datum, when compared with those 
found south of the Chalk escarpment. He would be glad of further 
information as to the mode of origin of the contortions in the brown 
clays, and the source of derivation of the chalk in the chalky clay ; 
also as to whether there were other and related drifts at higher 
levels, and whether there was any great difference in the derived 
fossils or erratics contained in the various clays. 

Prof. Warts referred to the existence of ‘infant-mortality beds’ 
in rocks at several other horizons, as well as in the Lias. Thus 
in the Bala Beds there is a zone characterized by minute trilobites, 
and the Wenlock Shales and Tarannon Shales are marked by minute 
brachiopods. 

Mr. R. S. Herriss stated that he had had the advantage of 
going over most of the ground with the Author, and congratulated 
him on his paper. He wished to know whether the Author had 
any views as to the source of origin of the chalk which went to 
form the Chalky Boulder Clay of the district described. 

The PrusipEnt also spoke. 

The AvrHor, in reply to Mr. H. B. Woodward, said that 
whereas the great Chalky Boulder Clay of the districts that he knew 
occurred above the so-called ‘ Mid-Glacial’ gravels, the brown 
contorted Boulder Clay near Rugby certainly occurred below these 
gravels, although it contained chalk in abundance in places. 

The Author agreed with the Rev. J. F. Blake in his suggestion that 
the fauna of the Lower Lias of Northamptonshire and Warwickshire 
agreed rather better with that of Yorkshire than with those of 
districts to the south-west, but he did not think that the specimens 
of Ammonites polymorphus, A. trivialis, and A. bufer were immature. 

In reply to Mr. Salter, he said that the subject of the probable 
origin of the contortions in the brown Boulder Clay had been discussed 
elsewhere (Proc. Geol. Assoc. vol. xv, p. 430), and that he had never 
yet been able to form a clear idea of the conditions capable of pro- 
ducing in these districts Glacial deposits, made up in one place 
chiefly of Oxford Clay, in another of Kimeridge Clay, in another to 
a considerable extent of Carboniferous and other old rocks, but 
always associated with chalk and flints. 


Wools 55-| A MEGALOSAUROID JAW FROM BRIDGEND. 89 


6. On a Mreatosavrotn Jaw from Rumtic Beps near BripeEND 
(GuaMorGANSHIRE). By E, T. Newron, Esq., F.R.S., F.GS. 
(Read December 2ist, 1898.) 


[Communicated by permission of the Director-General of 
H.M. Geological Survey. | 


[Puate X.] 


THE specimen which forms the subject of the present communica- 
tion was obtained by Mr. John David, of Porthcawl (Glamorganshire), 
from a mason, who was engaged in preparing stone for building a 
wall, at Stormy Down, near Bridgend. It isa block of hard whitish 
sandstone, which, having been split open, revealed the impression of 
a reptilian jaw nearly 11 inches long. This fossil was shown to my 
colleague, Mr. R. H. Tiddeman, who, appreciating the value and 
interest of so unique a specimen, asked that it might be sent to the 
Geological Survey Museum for examination. Mr. David not only 
acceded to this request, but most generously presented the specimen 
to the Museum, in order that it might be preserved in a national 
collection. 

The block of sandstone was one of many which lie on the surface, 
and undoubtedly represent a bed which has weathered away in the 
immediate vicinity. Stormy Down is within the boundary of the 
Penarth or Rhetic Beds on the old edition of the Geological Survey 
map; but whether the bed which yielded the fossil lies above or 
below the Avicula contorta-shales is a point still under investigation. 

A number of internal casts of small lamellibranchs may be seen 
on the specimen, but they are too imperfect for identification : 
one of them is an oval shell with the umbo near the anterior third, 
and is in all probability Pullastra arenicola ; while another, rather 
larger and of triangular form, may be a Myophoria. 

I have received much valued assistance, in the comparison of this 
reptilian jaw with specimens in the British Museum (Nat. Hist.), 
from Mr. A. Smith Woodward and Mr. C. W. Andrews; and I take 
this opportunity of tendering to those gentlemen my warmest thanks. 


The bony matter of the fossil has disappeared, and thus what 
remains is a beautifully-preserved mould of the dentary bone of a 
Megalosauroid reptile with several teeth in place. The impression 
of the whole of the inner surface and the anterior half of the 
outer surface have been recovered, but the portion of stone con- 
taining the mould of the outer surface of the hinder half is wanting. 
The bone had evidently been much cracked by pressure while still 
included in the rock, and these cracks are well seen in the casts 
which have been prepared from the natural moulds. It is upon 
‘these casts that the figures and descriptions have been based. 

This dentary bone (Pl. X, fig. 1) measures 10:8 inches (275 mm.) 
in length, 2°6 inches (65 mm.) in depth at the hindermost part of 


90 MR. E, T. NEWION ON A MEGALOSAUROID Jaw [ Feb. 1899, 


the alveolar margin, 1°45 inch (37 mm.) immediately behind the 
anterior largest tooth, and a little less about 2 inches farther back. 
The entire bone is naturally narrow, but this narrowness has 
probably been exaggerated by the pressure which it has undergone 
in the rock. The lower margin, which is remarkably straight for 
the greater part of its length, has its anterior sixth curved upward 
till it reaches the alveolar margin. The lower edge of the bone is 
rounded and not more than °3 inch (8 mm.) thick at its widest 
part, which is about the middle of the bone, and thence it decreases 
regularly to the hindermost angle, where it is merely the lower 
edge of the thin vertical bone forming the outer plate of this 
part of the jaw. The outer portion of this bone stands about 
z inch higher than the inner part, thus forming a parapet, 
within which 16 or perhaps 17 alveoli may be counted. ‘The 
osseous divisions between the alveoli form triangular masses, as 
seen on the inner aspect, the broad bases of which are marked off 
from the inner margin of the jaw by a longitudinal groove. In 
this groove, and opposite the middle of each alveolus, there is a 
small pit, in which the successional teeth make their appearance, 
as may be seen at the bases of the fourth and of the hindermost 
large teeth (Pl. X, figs. la-b & 4). The front half of the inner 
aspect of this jaw is so like that of Megalosaurus, except for size, 
that the description of the latter given by Buckland’ would apply 
very well to the present specimen. 

Between 4 and 5 inches of the hinder part of the inner side 
of this dentary bone is occupied by a large triangular cavity, such 
as is common in reptilian jaws; the upper margin of this cavity is 
sharply defined by the inner alveolar plate, which forms a wide 
band below the alveolar margin, and, extending forward, becomes 
somewhat broader in the region of the symphysis. Posteriorly and 
inferiorly this alveolar plate is separated from the outer plate of the 
bone, by an extension of the triangular cavity upward between 
them; but, passing forward, this separation lessens, and then 
becomes a groove which extends forward to the symphysis. Near 
its anterior extremity a large foramen opens into this groove. 
Inferiorly the triangular cavity has a less distinct boundary; it 
is formed by a thickening of the lower edge of the outer plate, 
which increases in depth as it passes forward, and at the place 
where it approaches the alveolar plate to form the anterior point of 
the triangle there is a foramen penetrating the substance of the 
bone. This triangular cavity is similar to what is found in the 
crocodile, and doubtless, as in that creature, was covered by a splenial 
bone extending far forward, thus converting the groove into a 
covered canal for Meckel’s cartilage. There is a slight flattening 
of the front part of the inner surface, but it does not give one the 
impression that the two dentary bones met in a definite symphysis. 

The cast of the anterior half of the outer surface (Pl. X, fig. 2) 
presents some peculiarities which it will be well to notice ; it is com- 
paratively flat, and probably was never much more convex than it 


* Trans. Geol. Soc. ser. 2, vol. i, pt. ii (1824) p. 395, pls, xl & xli. 


Wal. 553i FROM RHZTIC BEDS NEAR BRIDGEND. 91 


now is. There is no ornamentation other than a slight streaking of 
the surface. A small part of the.bone is wanting in front, as may 
be seen if this portion (Pl. X, fig. 2) be compared with the corre- 
sponding part of fig. 1. Anteriorly a row of five foramina may 
be seen below the alveolar border, and these are followed by a 
shallow groove, which, descending a little, is continued to the 
hinder end of the cast, almost parallel with the alveolar border, 
and at about 4 inch from it; along this groove there are elongated 
depressions at irregular intervals, but these are not foramina, 
as might be supposed. Near the lower margin also there is a row 
of six or seven smaller foramina, and after an interval a groove 
continues the line to the end of the specimen. 

The lessening of the depth of the jaw between the third and 
fourth of the larger teeth (Pl. X, fig. 2) is due to the way in 
which the jaw was divided in the splitting open of the stone ; 
nothing of this is seen on the inner half (Pl. X, fig. 1). 

The teeth were lodged in deep sockets; six of them, fully de- 
veloped, are still in place (Pl. X, fig. 1). The anterior tooth is the 
largest, being 29 mm. above the outer margin, 12 mm. from before 
backward, and about 6 mm. thick. The hindermost of these six 
teeth stands only 14 mm. above the jaw. Five other teeth may 
be seen projecting, more or less, from their alveoli; and on the 
inner side, at the bases of the fourth and of the hindermost large 
teeth, the points of two successional teeth may be seen in the pits 
which have already been mentioned (Pl. X, figs. la—b & 4). Six 
of the alveoli are empty. 

The teeth are strongly curved; their posterior concave margins 
are serrated to within a short distance of the jaw, while the 
anterior convex margins are only serrated for about two-thirds of 
their length. The second of the large teeth shows the serration most 
perfectly (Pl. X, fig. 3): its concave margin stands 23 mm. above 
the jaw, and 20 mm. of this are sharp and serrated; the front 
convex margin measures 25 mm., of which the upper 16 mm. are 
sharp and serrated, while the lower part is rounded and not serrated. 
This proportion of serration on the anterior margin is practically 
the same on all the teeth. 

From the foregoing remarks the mode of succession’ of the 
teeth may be clearly understood. The new teeth are developed in 
or close to the little pits seen on the inner sides of the functional 
teeth, where their points first appear, as shown at the bases of 
the fourth and sixth large teeth (Pl. X, fig. 1,a & 6). Doubtless, 
as in some well-known reptiles, the pressure of the new and 
growing tooth upon the inner side of the old one caused its 
absorption, until at length the young tooth would occupy the 
inside of the fang of the old tooth. This stage is not shown in 
the present specimen. The continued growth of the new tooth 
causes the absorption of the old one, until it is so weakened that 
it is broken off or falls out, and then the new tooth is found occu- 
pying the middle of the alveolus. Several such young teeth may 
be seen protruding more or less from their alveoli in this specimen. 


92 MR. E. T. NEWTON ON A MEGALOSAUROID JAW [ Feb. 1899, 


The resemblance which this jaw bears to the corresponding 
parts of Megalosaurus is so striking that the reference of the fossil 
to the same genus appears, at first sight, to be justifiable. <A 
nearer comparison, however, shows that the teeth of the present 
specimen are less compressed and more curved than in Megalo- 
sawrus, besides being smaller than in any known species of that 
genus. ‘The vascular apertures of the outer surface appear to be 
differently placed. Moreover Megalosaurus is essentially a Jurassic 
genus, and although representative species have been found in 
newer formations, even to the top of the Chalk, yet it has not been 
recognized in beds older than the Inferior Oolite. The nearly-allied 
North American genus Ceratosaurus is likewise of Jurassic age. 

Similarly serrated and compressed teeth have been found in 
beds of Liassic, Rhetic, and Triassic age, but these have been 
referred to other genera. 

It was Huxley,’ in his classical paper, who first definitely 
established the occurrence of Dinosaurian reptiles in British Triassic — 
rocks; but he was careful to point out that Riley & Stutchbury ” 
had already noticed the resemblance which a large femur from 
the Bristol Magnesian Conglomerate bore to that of Megalosaurus, 
and that Owen* had subsequently referred this femur to the 
Dinosauria. 

The genera Thecodontosaurus and Palewosaurus, so named by 
Riley & Stutchbury from fossils found in Triassic conglomerate and 
preserved in the British Museum (Nat. Hist.), were shown by Huxley 
to be true Dinosaurs. The teeth of the former genus are leaf-shaped 
and serrated, while those of the second are curved and lanceolate, 
with the serrations of the anterior edge extending only ashort distance 
from the apex. The teeth of Palcwosaurus resemble somewhat those 
of Megalosaurus, but differ from them in being more cylindrical. 

Certain teeth from the Warwickshire Trias, now in the Museum 
of Practical Geology, were also referred to Palewosaurus by Huxley, 
and a larger tooth, much compressed and serrated throughout the 
anterior and posterior margins, was placed in the genus Terato- 
saurus.’ This tooth is scarcely distinguishable from one belonging to 
Megalosaurus superbus of the Gault,’ in which the serration of both 
margins is coextensive with the tooth-crown. 

The characters by which Megalosaurus is distinguished from 
Teratosaurus are seen in the vertebre and limb-bones, and as these 
parts of the skeleton were not found with the Warwickshire tooth, 
Huxley was justified in referring it to the latter genus. Moreover, 
Megalosaurian remains have not been recognized in Triassic beds. 

Mr. R. Lydekker* has pointed out the identity of Plieninger’s 
genus Zanclodon (1846) and Von Meyer’s genus Teratosaurus (1861), 


1 Quart. Journ. Geol. Soc. vol. xxvi (1870) pp. 32-50 & pl. iii. 

2 Trans. Geol. Soc. ser. 2, vol. v, pt. ii (1836) p. 349. 

3 ¢ Paleontology,’ 2nd ed. p. 278. 

4 Huxley, op. cit. pl. iii, fig. 11. 

5 Gaudry, ‘Enchainem. du Monde Anim.: Foss. Second.’ 1890, p. 222. 
6 Cat. Foss. Rept. Brit. Mus. pt. i (1888) p. 172. 


Vol. 55.] FROM RHZTIC BEDS NEAR BRIDGEND. 93 


and he has in the same place expressed the opinion that the 
Warwickshire tooth described by Huxley may belong to Zanclodon 
suevicus of Von Meyer. Another but smaller tooth in the British 
Museum (Nat. Hist.), referred doubtfully by Mr. Lydekker to 
Zanclodon, is from the Lias of Lyme Regis. 

Owen’ gave the name of Cladyodon Lloydii to a similarly 
compressed, but apparently much more slender tooth, from the 
Keuper of Coton End, Warwick. 

A few Dinosaurian bones have been recorded from beds of Rheetic 
age. So long ago as the year 1849 Stutchbury ? called attention to 
a big bone from the Rheetic Bone-bed of Aust Cliff, which measured 
2 feetin length, although wanting both extremities; but, with this 
exception, anything like Dinosaurian remains was unknown from 
beds of this age until the year 1894, when Mr. W. A. Sanford? made 
known the discovery of some large bones and teeth, of an animal 
resembling Megalosaurus, in Rhetic beds at Wedmore, near 
Glastonbury. 

These remains have since been described more in detail by 
Prof. Seeley, who has proposed two new genera and two new 
species for their reception, namely, Avalonia Sanfordi and Picrodon 
Herveyi. The specimens included in the first of these genera are a 
much-worn tooth of Megalosaurian or Zanclodon type, a femur, a 
dorsal vertebra, and two phalanges. The tooth has the posterior 
edge sharp and serrated; the anterior side is rounded and, in its 
present condition, devoid cf serrations; but the tooth is very much 
worn, and it is probable that when perfect the anterior margin was 
serrated near the apex. Notwithstanding the restricted serration 
of this tooth, its affinity is rather with Zanclodon than with Megalo- 
saurus. The peculiarities of the femur and vertebra which, with 
those of the tooth, are relied upon for their generic separation from 
Zanclodon are seemingly but small, and one cannot feel convinced 
that the genus Avalonia rests upon a sure foundation. 

With regard to the tooth and bones named Picrodon, there is a 
greater difficulty, for it seems probable that they are parts of the 
same skeleton as the remains named Avalonia. All the bones 
were found together at the same place; and, besides this, the chief 
character said to be distinctive of the tooth_—namely, the obliquity 
of its serrations—is so slight as to be scarcely perceptible. 

In comparing the Bridgend Dinosaur with the nearly-related 
forms above noticed, we are practically limited to the form of the 
teeth, for, with the exception of Megalosaurus, the jaw of which 
has already been mentioned, and the little Ornithosuchus from 
Elgin, no lower jaws are available for comparison. This is 
unfortunate, for the distinctive characters of these Dinosaurian 
genera are to be sought in the vertebree, pelvis, and limbs. The 


1 Rep. Brit. Assoc. 1841 (Plymouth) p. 155, and ‘ Odontography’ (1840-45) 
Dp. 268, pl. lx", fig. 4. 

2 Rep. Brit. Assoc. 1849 (Birmingham) p. 

3 Proc. Somerset. Arch. Nat, Hist. Soc. Fe “i (1894) p. 227. 

4 Geol. Mag. 1898, p. 1. 


94 MR. E. T. NEWTON ON A MEGALOSAUROID JAW [Feb. 1899, 


extent of the serration on the auterior border of the teeth has 
been thought to be some guide to their generic affinities; but the 
variations in this respect to be seen among the species included in 
the genus Megalosaurus show that this character can hardly be 
relied upon for more than specific distinction. Megalosaurus Buck- 
landi, from the Lower Oolites, has the serration of the anterior 
border of the teeth limited to the apical third of the enamelled 
crown; in MW. insignis, from the Upper Oolites, it extends for two- 
thirds the length of the crown; and in M. superbus, from the 
Cretaceous rocks of France, it is apparently coextensive with the 
crown. 

A similar variation is found among the Megalosauroid teeth 
occurring in Triassic rocks; but specimens from those strata have 
been placed in several genera, as already mentioned. Of these only 
Zanclodon, Palewosaurus, Cladyodon, Avalomia, and Picrodon need 
be again discussed, and some at least of these might with advantage 
be included in the genus Zanclodon. The teeth of Zanclodon 
suevicus, with which may be included the Warwickshire tooth 
described by Huxley under the name of Teratosaurus, are more 
compressed, and have the anterior serration extending farther down 
the crown than in our Bridgend specimen. Palcosaurus cylin- 
drodon has the teeth more cylindrical than in the present fossil, 
although the serration may have been much the same. ‘The tooth 
named Avalonia Sanfordi (with which I should include Pierodon 
Herveyi) has a close resemblance to those of the Bridgend reptile, 
but the imperfection of the Wedmore specimens prevents a satis- 
factory comparison of their serration, and these teeth are less curved 
than are those of the Bridgend jaw. 

Inasmuch as it does not appear to me that the generic distinct- 
ness of Avalonia is well established, I am constrained to refer the 
Bridgend reptile to the genus Zanclodon ; and as it differs from any 
recorded species, this Welsh Dinosaur may appropriately be named 
Zanclodon cambrensis. 


EXPLANATION OF PLATE X. 
Zanclodon cambrensis, sp. Nov. 


[From Penarth Beds (Rhztic?), Stormy Down, Bridgend, Glamorganshire ; 
obtained by Mr. John David, of Porthcawl, and presented to the Museum of 
Practical Geology, Jermyn Street. The specimen being merely a hollow mould, 
the figures have been drawa from casts made in gutta percha. | 


Fig. 1. Inner side of the left dentary bone. About 2 nat. size. The points of 
young teeth are shown at the bases of a & 6. 
2. Outer surface of the anterior portion of the same dentary bone. 
3. Portion of bone with two teeth, seen from the inner side. Nat. size. 
T'o show the serration of the teeth. 
4. Tooth a of fig. 1. Nat. size. To show the new tooth appearing in a pit 
at the base. 


Vol. 55.| FROM RUZ TIC BEDS NEAR BRIDGEND. 95 


Discussion. 


Prof. SrrLey said that he had examined all the known remains of 
fossil reptiles from the Trias, and had been impressed by their diversity 
in the limb-bones and pelvis. This led him to a detailed examination 
of the teeth, which among the Megalosauroid forms show two con- 
ditions, defined by crenulation of the margins. First, in Dimodo- 
saurus, Thecodontosaurus, and Picrodon the crenulations had a 
serrated character, with the denticles not at right angles to the 
margin of the tooth but more or less directed upward, differing in 

egree, as well as in the form of the crown. Secondly, in Palao- 
saurus, Zanclodon, Avalonia, and Huskclosaurus, the denticles more or 
less resembled Megalosaurus in being at right angles to the cutting- 
margin of the tooth; but in each genus they differ in shape and size, 
and the character of the crown is different. These modifications, 
which were once regarded as indicating species of Megalosaurus, are 
known to be associated with various types of skeleton, no one of 
which has much in common with that genus. When it was pro- 
posed to refer Mr. Newton’s fossil to Zanclodon, there was the 
difficulty that no dentary bone of that genus is known. The 
reference is therefore hypothetical. A tooth of Zanclodon had been 
figured, but it shows striking differences from the teeth in this jaw 
from South Wales. It is highly probable that the maxillary bone 
with teeth, named Teratosaurus, may be the skull of Zanclodon, but 
the inflated teeth of that genus are unlike the impressions from 
Mr. Newton’s specimens. He found no ground for placing this 
fossil with Zanclodon, which is an unknown type so far as its jaw is 
concerned. ‘The resemblance, however, is remarkably close with the 
tooth of Avalonza, and in no other genus was he aware of comparable 
generic characters. Moreover the femur and other bones of Ava- 
lonia are in the British Museum, and the femur and corresponding 
bones of Zanclodon are in the Royal Museum at Stuttgart; and 
comparison shows that the differences between them are generic. 
The femur differs in proportions, in depth of the distal end, in 
position of the lateral trochanter, and in form of the proximal end. 
Avalonia and Zanclodon were very distinct genera. He approxi- 
mated the South Wales fossil to the British genus Avalonia. On 
whichever side the weight of evidence in interpretation is found to 
incline, he congratulated the Author on having made a beautiful 
addition to our knowledge of the Zanclodontide. 

Mr. H. B. Woopwarp said that, in the opinion of Mr. Strahan 
(who regretted his inability to be present), the horizon of this fossil 
might eventually prove to be either Rhetic or Upper Keuper. The 
ground was still under examination by Mr. Tiddeman. It was, 
however, a matter of no great importance whether these passage-beds 
were called Rhetic or Keuper. Near Wedmore, in Somerset, where 
similar Saurian remains had been found, there were sandy strata, 
with Pullastra arenicola, beneath the black Avicula contorta-shales, 
The passage-beds, in the areas mentioned, were most closely allied 
to the Rheetic formation. 


96 A MEGALOSAUROID JAW FROM BRIDGEND. [Feb. 1899, 


Prof. Sozzas pointed out that Palewosaurus and Thecodontosaurus 
had priority over Zanclodon by at least 12 years, and consequently 
species rightly referred to these genera should retain the names 
originally given to them. 

Dr. Woopwarp said that, as one of those who was present, with 
Dr. Hinde, at the exploiting of the Wedmore Dinosaur, he confessed 
to a feeling of doubt as to the existence of two genera (Avalonia 
and Picrodon) founded on a few detached bones and two teeth, which, 
according to the present Author’s showing, might have been derived 
from the jaw of one animal; indeed, he ventured to think that the 
weight of evidence was in favour of this view. For if, as the 
Author had pointed out, the slight variation in the serration of 
Megalosaurian teeth could be shown to exist in individual teeth in 
the same jaw, this character was insufficient for generic separation ; 
and if the Author had erred, he had done so on the side of caution, 
in refraining from adding a new generic appellation to those already 

iven. 
¥ Mr. C. W. Anprews and the Rev. H. H. Winwoop also spoke. 

The AurHor, in reply, said that he agreed with Prof. Seeley as to 
the close resemblance between the teeth of the Bridgend specimen 
and that which had been named Avalonia, but differed in preferring 
to place the former fossil in the genus Zanclodon, which he under- 
stood to include Teratosaurus. The serrations observable on the tooth 
referred to Picrodon by Prof. Seeley did not appear to him to be of 
the type found in Thecodontosaurus to which allusion had been made, 
nor did he think it sufficiently different from Avalonia to justify its 
separation from that form, or indeed from Zanclodon., 


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Vol. 55.] PERMIAN CONGLOMERATES OF THE LOWER SEVERN BASIN. 97 


7. The Perwian Conetomerates of the Lower Szvern Basin. By 
W. Wicxuam Kine, Esq., F.G.S. (Read December 7th, 1898.) 


[Puarus XI & XII—Maps. ] 


ConTENTs. 
Page 
Me EOE ELOTE Be aioe es tio aac 3 cao « onde ee etna Aetna oe ob 97 
IT. Distribution of the Middle and Upper Permian .................. 100 
III. General Features of the Middle Permian ...................eeeeeeee 101 
IV. General Features of the Upper Permian ....................000e008 102 
V. Relationship of the Upper Permian to the Trias .................. 102 
VI. Stratigraphy of the Middle and Upper Permian in 
(1) South-east Shropshire, 1 a eee ‘ge 102 
16 Warshill 
(2) South Staffordshire, 2a Clent Hills 
26 Stour Valley | pecans 111 
2c Warley-Barr 
VII. Conclusions based on the Variation in the Coarseness of the 
LVS Pere EWS Na SN Os OSE PR fo ont Ae OF OR R= Seen Ce, Se eee on 118 
VIII. The Pebbles of the Middle Permian Conglomerates ............... 118 
PACER et) (SO GMOS ae cota 3 i nda own ome emnsiie <a -Beepicin sin Anee cence 123 


I. Intropuction. 


BeEtweeEn the River Severn and the village of Enville in South-east 
Shropshire, and again round the southern half of the South Staf- 
fordshire Coalfield, there are certain bands of rocks cemented and 
hardened by calcareous matter—namely, calcareous conglomerates, 
cornstones, and calcareous gsandstones—which constitute parts of 
the group classified by the officers of the Geological Survey as 
Middle Permian. The object of this paper is to trace the materials 
composing these calcareous rocks to their sources. 
The typical Permian sequence of the Shropshire type is, according 
to Prof. Hull, as follows, in descending order *:— 
(1) Upper Permian. Red and purple sandstones and marls (300 feet). 
(2) Middle Permian (130 to 500 feet). 
(a) Trappoid breccia. 
(6) Sandstone and marl. 
(c) Calcareous conglomerate. 
(d) Sandstone and marl. 


(2) Calcareous conglomerate. 
(3) Lower Permian. Purple sandstones, often calcareous, interstratified 


with red marls (850 feet). 


Murchison? stated that at Coton and Bowhills the calcareous 
horizons of the Middle Permian consist of ‘ (a) coarse conglomerate, 
composed chiefly of fragments of Carboniferous Limestone, generally 
rounded; .... some of them are of an oolitic structure .... (6) con- 
glomerate, with fewer fragments of limestone, but pebbles of quartz, 


1 Mem. Geol. Surv. 1869, ‘Triassic & Permian Rocks of the Midlands,’ 
pp- 13 e¢ segg., & descr. of Horiz. Sect. 2, Sheet 53, p. 6. 
? <Silur. System,’ 1839, p. 48. 


GJ. Gos. No: 217. H 


98 MR. W. WICKHAM KING ON THE PERMIAN’ [Feb. 1899, 


Old Red Sandstone, etc. .... and minute fragments of jasper. He 
pointed out that ‘the nearest known masses of similar [Carboni- 
ferous]| rock are in the Carboniferous Limestone of the Clee Hills.’ 

Ramsay' collected from conglomerates, included by him in the 
Middle Permian, at Gatacre Hall? and Four Ashes, near Enville, 
pebbles of 


Red sandy marl. Quartz. 


Red sandstone. Black slate. 
Carboniferous Limestone. Hornstone. 
Chert. Red jasper. 
Silurian limestone, of doubtful age. * Red granite. 
Sandstone. Greenstone. 

3 Quartz-rock. * Felspathic trap. 


* Banded felspathic ash. 


He states that ‘the Carboniferous Limestone pebbles by far 
predominate,’ and that ‘the nearest Carboniferous Limestone is 
that of the Titterstone Clee Hills.... The Coalbrookdale lime- 
stone contains chert .... and in the same district occur igneous and 
quartz-rocks not dissimilar to those found in the Conglomerates. 
Some of the other pebbles may have come from the Welsh Border 
near the Longmynd; but all of them may have been drifted by 
ordinary marine action.’ 

Jukes* described shortly the outcrops of these calcareous bands 
in the South Staffordshire region, but offered no opinion as to 
their origin. 

Prof. Hull* dealt with the different localities where these calcareous 
bands occur in the Midland Counties, and gave it as his opinion 
that ‘they are the fragmentary representations of an old shingle- 
beach, which once stretched at intervals over a large part of Salop 
and the adjoining parts of England.’ 

Mr. G. E. Roberts’ stated that ‘ rolled fragments of a yellow clayey 
rock may be met with in these calcareous bands [| of South-east Shrop- 
shire], and the same rock is am situ in the Old Red Sandstone area 
of Trimpley, close by.’ 

[Mr. Howell® states that the Middle Permian in the Warwick- 
shire Coalfield, an area outside the region now described, contains 
Carboniferous Limestone-pebbles, and Leicestershire is the nearest 
locality where that limestone is in place, but they may have been 
derived from other masses concealed beneath the Trias. | 


1 Quart. Journ. Geol. Soc. vol. xi (1855) p. 189. 

2 The only quarries, either new or old, at or near Gatacre Hall are in the 
Permian breccia. In my opinion, those rocks marked in the list with an asterisk 
were from Gatacre Hall, and should be struck out. The quarry at Four 
Ashes is in the caleareous conglomerate. Ramsay’s specimens are now in the 
Museum of Practical Geology, Jermyn Street. 

3 Mem. Geol. Surv. 1859, ‘South Staffs Coalfield,’ 2nd ed. pp. 13-15, 177, 
183 & 184. 

4 Mem. Geol. Sury. 1869, ‘Triassic & Permian Rocks of the Midlands, 
p. 14, ete. ; & descr. of Horiz. Sect. 2, Sheet 53. 

> «Rocks of Worcestershire,’ 1860, p. 116. 

6 Mem. Geol. Surv. 1859, ‘ Geol. of Warwickshire Coalfield,’ p. 30. 


Vol. 55.] CONGLOMERATES OF THE LOWER SEVERN BASIN. 99 


Mr. Cantrill' discovered ‘the presence in these [calcareous | con- 
glomerates [of South-east Shropshire] of rounded masses of Spzrorbis- 
limestone.’ 

[The foregoing references are all the original observations 
hitherto published on these Permian conglomerates; but the 
Permian breccia literature is more or less closely connected with 
their origin. 

Buckland? thought that the materials composing the Permian 
breccias near the Lickey came from hill-ranges to the south. 
Murchison® considered that some of the patches of Permian breccia 
consisted ouly of, and rested upon, solid trappean rocks, but that 
others near Malvern were the basal conglomerate of his New Red 
system, and were locally derived. Phillips* stated that ‘the origin 
of the fragments was a not-far-removed metamorphic range now 
invisible.’ Ramsay”° claimed that the Welsh Border was the source, 
and alleged that there was a Permian glacial period. The proofs of 
the latter conclusion have been subjected to much criticism by 
Phillips,’ Bonney,” Prestwich,’ Hughes,” Sir A. Geikie," and others. 
Jukes gave it as his opinion’ that ‘ the fragments might be derived 
from adjacent rocks now concealed under the Permian and New 
Red Sandstone of the neighbourhood.’ Prof. Hull” quoted Ram- 
say’s and Jukes’s views, and stated that ‘the southern margin of 
the Permian basin....was probably formed at no great distance to 
the southward of the Permian areas of South Staffordshire and 
Warwickshire by the upraising of the old Silurian rocks.’ 

When Prof. Lapworth made known in 1882™ the Cambrian and 
pre-Cambrian age of the old ridges of the Lickey and Nuneaton, 
the local derivation of these materials that he has ever since advo- 
cated became more plausible. Mr. H. T. Brown,” in his brilliant 
paper on the Permian rocks of Leicestershire, demonstrated that the 


1 *Contrib. to Geol. of Wyre Forest Coalfield, p. 34 (Kidderminster, 
1895), 

2 Trans. Geol. Soc. ser. 1, vol. v (1819) p. 506. 

° «Silur. System,’ 1839, pp. 138, 419, 493, & 496 ; see also pp. 50-53. 

* Mem. Geol. Surv. vol. ii, pt. i (1848) p. 162; see also Trans. Malvern 
Nat. F.C. pt. i (1855) pp. 38 & 39, 

° Up to 1855 the Permian brescias were included in the Lower New Red 
Sandstone. 

6 Rep. Brit. Assoc. 1854 (L’pool), pp. 93, 94; Quart. Journ. Geol. Soc, vol. xi 
41855) p. 185; and lecture to Roy. Inst. , April 24th, 1857. 

7 Trans. Malvern Nat. F. C. pt. i (1855) pp. 38 & 39. 

8 Rep. Brit. Assoc. 1886 (Birmingham) p. 10; ‘Midland Nat.’ vol. ix (1886) p.1. 

® * Geology,’ vol. ii (1888) p. 133. 

10 Proc. Cambridge Phil. ae vol. vili, pt. ili (1893) p. 111, 

11 ¢Memoir of Sir A. C. Ramsay, 1895, p 62. 

12 Mem. Geol. Surv. 1859, ‘ South Staffs ‘Coalfield, 2nd ed. p. 15. 

13 Mem. Geol. Surv. 1869, ‘Triassic & Permian Rocks of the Midlands, 

. 15-19, 28 & 29; see also ‘Coalfields of Great Britain,’ 4th ed. (1881) pp. 132, 
: i, & 521-528, 

14 See Birm. Phil. Soc. Proce. vol. iii (1882) pp. 237, 238; Geol. Mag. 1882, 

p. 565, 566; Brit. Assoc. Handbook (Birmingham, 1886) ; and Proce. Geol. 
hesbe vol. xv (1898) pp. 872-377. 
1 Quart. Journ. Geol. Soc, vol. xlv (1889) p. 1; see also T. G. Bonney, 
“ Midland Nat.’ vol, xv (1892) pp. 25 & 49. 
HZ 


100 MR. W. WICKHAM KING ON THE PERMIAN ___[ Feb. 1899,. 


materials, both angular and rounded, were derived from local 
ridges now partly buried beneath the Trias. Mr. A. J. Jukes- 
Browne supports the local derivation,’ and suggests that reason 
may be found for uniting the Dyas and Trias into one system under 
some such name as Mercian.” My conclusions? that the Clent Hills. 
breccias are locally derived and accumulated, like beds in Persia 
described by Dr. W. T. Blanford,* have already been announced. 
Mr. R. D. Oldham’ thinks that some of the fragments are glacially 
striated, and acknowledges the proofs of southern derivation ascer- 
tained by Midland geologists. The foregoing concise summary is. 
not exhaustive. | 


Il. Disrrrpution oF THE MippLE anD Uprrer Permian. 


The Permian, in the regions under description, is divisible into 
three lithological groups :— 


(1) A lower group of marls and sandstones. 

(2) A middle group of calcareous sandstones, locally conglomeratic, inter- 
bedded with marls and sandstones. 

(3) An upper group of marls, with included breccias. 


The only difference between this classification and that of 
Prof. Hull is that the trappoid breccias are now classed with the 
Upper Permian instead of the Middle. 

Some of the local outcrops of these Middle Permian calcareous 
bands are marked on the Geological Survey maps. The whole of 
the outcrops in South-east Shropshire, as I have worked them out in 
the field, are shown in the map accompanying this paper (Pl. XI). 

These beds occur in two main regions, namely (1) the region of 
South-east Shropshire between the River Severn and the village 
of Enville; and (2) the region of South Staffordshire, around the 
margin of the southern half of that coalfield. 


(1) The South-east Shropshire Region. (Pl. XI.) 


la. In the Bowhills-Enyille district these bands are exposed at 
Bowhills, ranging to Ridney Hill. The strike is S.S.E. and 
N.N.W. In places they dip about 5° E.N.E., but are usually 
flat. A fault bounds these exposures on the E.N.E. From 
1 to 2 miles beyond the fault the same beds again crop out 
between Compton, near Enville, and Gatacre, near Bridgnorth. 
The strike is 8.8.E. and N.N.W., with dips varying from 3° to 6°, 
16. The Warshill district is situated on the south-eastern edge of the 
Trimpley Oid Red Sandstone anticlinal, while the Bowhills-to- 
Ridney-Hill outcrops occur on its north-western side. At 
Warshill one band is exposed. The strike is 8.W. and N.E., 
and the dip is south-easterly. The district is bounded by faults. 
1 «Building of the Brit. Is.” 2nd ed. (1892) pp. 152-170. 
2 «Handbook of Historical Geol.’ 1886, p. 282. 
3 ‘Midland Nat.’ vol. xvi (1893) p. 25. 


4 Quart. Journ. Geol. Soc. vol. xxix (1878)-pp. 496-501; see also W. K. 
Loftus, ibid. vol. xi (1855) p. 252. ° Lbid. vol. 1 (1894) p- 465. 


Vol. 55.] CONGLOMERATES OF THE LOWER SEVERN BASIN. 101 


(2) The South Staffordshire Region. (Pl. XII.) 


2a. In the Clent Hills district these Middle Permian calcareous 
bands crop out, more or less continually, in the low ground at 
the southern end of the South Staffordshire Coalfield. 

26. In the Stour Valley district they reappear, north-west of the 
Clent Hills district, on the western side of the same coalfield, 
between Stourbridge and Kingswinford, and again at Baggeridge 
Woods and Sedgley Hall. 

2c. In the Warley-Barr district they are fairly well developed— 
north-east of the Clent Hills district, on the eastern side 
of the coalfield between Brand Hall and Langley (= Warley 
area), and again at Handsworth and Great Barr. 


III. Generat Features oF THE MippLE PERMIAN. 


The entire Middle Permian series is thickest and most complete 
in the Bowhills-Enville district. Three calcareous zones are present, 
divided by marls and sandstones, the whole resting conformably on 
the Lower Permian. The series appears to be thinnest at Warshill, 
where only one calcareous band is visible, resting upon mazrls. 
Four miles to the south, at Stagbury Hill on the Severn, these 
Middle Permian calcareous zones are wholly wanting. Still farther 
south, at Abberley, the local trappoid breccia rests on the Silurian. 
This Abberley breccia? and those occurring to the south at Alfrick, 
etc., and indeed ascending into the Keuper Marls at Tortworth, 
form a group of breccias which are of post-Permian age, and there- 
fore any further mention of them will be deferred. 

When these Middle Permian calcareous beds are carefully studied 
in the various districts, it is found that they present as a group the 
following peculiarities :— 


(i) They change, when followed for fairly long distances, from 
conglomerates to sandstones; but they usually retain their more or 
less calcareous character throughout, and thus can be followed 
in the field as prominent ridges between the lower grounds, eroded 
out of the softer sandstones and marls. 

(11) The component materials of any given calcareous zone decrease 
in size in definite directions when followed across country: the 
pebbles of the conglomerates becoming smaller and more rounded, and 
gradually dying out altogether as the rock passes into a sandstone. 

(iii) In definite directions, the beds between the lowest two 
ealecareous zones change from marls to sandstones. 

(iv) As a general rule, in proportion as the pebbly or marly 
materials of any band are replaced by sandstone, the band itself 
increases in thickness. 

(v) The pebbles forming these conglomerates vary, stage by stage, 
from about 21 inches in length down to rounded sand-grains. 

(vi) The pebbly materials are chiefly limestones, intermixed with 


1 For a short account of the Alpine structure of ue Abberley Hills, see 
Proc. Geol. Assoc. vol. xv (1898) pp. 425, 426.» 


102 MR. W. WICKHAM KING ON THE PERMIAN _—_[Feb. 1899, 


which are fragments of hard sandstone, of quartzite, and of vein- 
quartz. In some districts many pyroclastic rocks occur, but in most 
areas fragments of these are rare and very small. 

(vii) The age of many of the pebbles in the conglomerate-bands 
can be determined satisfactorily by the fossils which they contain. 

(viii) Many of the pebbles, both fossiliferous and unfossiliferous, 
belong to special lithological types still existing in place as rock- 
masses in the Lower Severn basin. 


LV. GENERAL FEATUREs OF THE Upper PERMIAN, 


Overlying this calcareous group is a series of breccias, sandstones, 
and marls. The lowest of this series is the well-known trappoid 
breccia, which has hitherto been included in the Middle Permian. 
I find, however, that there are other bands of breccia, in the series, 
interstratified with marls and sandstones; and theretore I have classed 
this trappoid breccia, together with all the Permian rocks above its 
base, in the Upper Permian of the Lower Severn basin. As these 
Upper Permian breccias and associated marls and sandstones show 
a marked horizontal decrease in coarseness, similar to and parallel 
with that of the calcareous bands of the Enville Middle Permian, 
they will also be discussed briefly in the present paper. 


VY. RELATIONSHIP oF THE Upprr PERMIAN TO THE TRIAS. 


The true Permian rocks are always surmounted unconformably 
by strata of Bunter age. In the South-east Shropshire region, the 
basal bed of the Bunter is the Red Sandstone Series of the Lower 
Bunter or the Lower Variegated Sandstones. In the South Stafford- 
shire region the base is usually formed by the Middle or Bunter 
Pebble-bed. 


VI. SrraticRaPHY oF THE MIDDLE AND eee PERMIAN. 
(1) The South-eas: Shropshire Region. (Pl. XI.) 
la. The Enville District. (Section & Table I, pp. 106-107.) 


This is unquestionably the typical district for the succession of 
the Permian deposits of the Lower Severn basin. The Middle 
and Upper Permian area itself is 4 miles long and 23 miles broad, 
and is almost a parallelogram in shape. The Permian strata, 
which dip to the east-north-east, crop out in parallel bands along its 
greater length from south-south-east to north-north-west. The 
oldest Middle Permian band forms its south-western boundary. 

The successive zones of the Middle and Upper Permian follow in 
regular order, as the area is traversed from west-south-west to 
east-north-east, and the highest visible zones are followed uncon- 
formably along the north-eastern border of the parallelogram by the 
basement-beds of the Lower Bunter. The north-western and south- 
eastern boundaries of the area are fault-lines. 


Wols55.| CONGLOMERATES OF THE LOWER SEVERN BASIN. 103 


_ In the Enville district the whole of the Middle Permian sequence 
18 exposed from base to summit, and also the whole of the Upper 
Permian so far as known. 

The Middle Permian is made up of three persistent calcareous 
bands, each capped by aseries of sandstones (usually non-calcareous) 
and marls. These three calcareous bands may be distinguished as 
A", B', & C' respectively in ascending order, and the softer beds 
overlying each as A’, B’, & C’ respectively. 

The Upper Permian of the Enville district commences with a 
massive breccia, the so-called trappoid breccia, which will be 
distinguished as D'. This is succeeded by a considerable thickness 
of marls with one persistent band of breccia, and others of a more 
or less inconstant character: these marls and intercalated breccias 
will be collectively distinguished as D?. 


The Middle Permian of the Enville District. 


Band A'.—The basal band of the Middle Permian is best exposed 
immediately south-west of Tuckhill, at Boathole, and is marked 
by a low ridge along the whole of its course. It is more or less a 
calcareous sandstone throughout, and at Boathole is developed as a 
cornstone. Itis 10 feet thick in the south-eastern part of the district 
near No Man’s Green, retains the same thickness to beyond Tuckhill, 
two-thirds of its length, but increases to 20 feet near Broad Oak Hill 
at the north-western termination of the area. 

Band A*.—The overlying marls and sandstones are first seen at 
No Man’s Green, where they are 50 feet thick. They maintain 
about the same thickness (50 to 75 feet) throughout, but become 
collectively more sandy towards the N.N.W. At the north-western 
extremity of the area the greater part of this zone is a sandstone. 

Band B'.—The middle calcareous band is first seen at Compton. 
Here it is a massive conglomerate, 75 feet thick, intensely hard and 
compact. The largest pebble that I have found in it is 6 inches 
long, and many are4 inches. Half amile to the westward (at Birch 
Wood) the calcareous conglomerate splits into two bands, divided by 
sandstones (well seen at No Man’s Green), and the pebbles are far 
less frequent and smaller. A mile beyond Birch Wood, near 
Chidley’s Farm, the two bands become three, separated by sand- 
stones and some marl, and the collective thickness has grown from 
75 to 155 feet, or it has more than doubled. The highest band is 
most conglomeratic. The pebbles near Chidley’s Farm are more 
abundant and larger than at No Man’s Green, while they are of 
about the same size as at Compton to the south, but less abundant. 
Half a mile north of Chidley’s Farm there is a fault, and in all 
the area to the north-north-west of this fault pebbles are rare in 
band Bb’. Half a mile north of the fault the three bands have 
come together again near Tuckhill, and form a magnificent ridge. 
The fine exposures which exist at and near Tuckhill exhibit 
about 10 feet of cornstone at the base, 60 feet of red calcareous 
sandstone, and an upper zone (say 5 feet) of conglomerate. The 


104 MR. W. WICKHAM KING ON THE PERMIAN [ Feb. 1899, 


pebbles are small, the longest that I have found measuring only 
2 inches. Less than 3 mile to the northward, at Broad Oak Hill, 
this zone is a massive calcareous sandstone devoid of pebbles. It 
retains this character up to the north-western end of the district, 
and is reduced to the thickness first noted, of 75 feet. 

Band B?.—The overlying strata are red marls and sand for about 
the first mile of their course, with a thickness of only 20 feet. 
They then become gradually more sandy, eventually passing into 
red and mottled sandstones with some marly seams, and as such 
are well exposed in and near the road from Tuckhill to Six Ashes, 
where they are 90 feet thick. They retain this character for 
the remainder of their course, but increase in thickness to about 
110 feet. 

Band C’, for about the first 2 miles of its course—namely, 
from Compton to near Four Ashes—is a calcareous sandstone, and 
increases in thickness from only 10 feet at Compton to 30 feet 
near Four Ashes. At the Green, Four Ashes, it becomes in its 
central part a 10-foot conglomerate, which with the underlying 
and overlying calcareous sandstones forms a prominent rib, 30 feet 
thick at the Green, but measuring at least 40 feet at Four Ashes 
Hall, close by. The largest pebbles here are about 5 inches long, and 
many measure 3 inches: they are all rounded fragments. At Six 
Ashes, 1 mile north-west of the Green, Four Ashes, the basal parts 
have gradually become a conglomerate, 20 feet thick, with inter- 
calated sandy bands. The change can be seen on the ground in several 
intermediate sections. ‘This conglomerate is succeeded by a band 
of loose sandstone (10 feet thick), and then by a second conglomerate, 
about 15 feet, making a collective thickness of 45 feet. The pebbles 
at Six Ashes are much the same size as at Four Ashes. For the 
next 3 mile the surface-indications and one quarry show that the 
pebbles are gradually disappearing, and at the end of this distance 
the whole band has become a massive calcareous sandstone, 50 feet 
thick, forming, at and near Gatacre, for the last mile of the north- 
western extremity of the area, a very prominent physical feature 
in the landscape. 

Band OC? is very indifferently exposed, the best section being 
seen in a pool east of Four Ashes. The beds are red marls 
throughout, from 25 to 35 feet thick, the greater thickness being 
to the south. Their geographical position is fixed on the ground, 
by the width of the platform between the two steps formed by C* 
and D’, but it is somewhat difficult to follow. 


The Upper Permian of the Enville District. 


The Upper Permian of the Enville district commences at the 
southern end as coarse breccia (D'), with angular fragments of 
pyroclastic rocks and of sundry sandstones—some of them more 
than 12, and very many 6 inches long, thickly set in a marly 
paste. The thickness of this breccia at and near Compton, near the 
‘south-eastern boundary, is about 225 feet. At the north-western 


Nol-t55, | CONGLOMERATES OF THE LOWER SEVERN BASIN. 105 


extremity of the area, 4 miles distant, there is only 25 feet of actual 
breccia that can be paralleled with the breccia at Compton and the 
Sheepwalks, Enville, and the materials are more rounded than in 
the south. 

At Compton and the Sheepwalks, as we pass up through the 
225 feet from the base to the summit, the fragments for the first 
50 feet increase gradually in size, but at 150 feet above the base 
become smaller again, while more marly material is intermixed with 
the layers of breccia-fragments, until at last the rock-fragments 
practically disappear and we find ourselves in the overlying zone 
Classified as D’. At Gilbert’s Cross the upper portion of D' is typically 
shown: here the breccia 1s intermixed with much marl, and definite 
layers of consolidated sandstione occur, containing some small 
breccia-fragments (not exceeding as a rule 2 inches in length), 
which I term breccia-sandstone. At Gatacre, near the north- 
western extremity of the area, the lower zone D' is still a typical 
breccia (25 feet) containing subangular fragments rarely exceeding 
6 inches in length, but this j iS overlain by a mass of marls and of 
breccia-sandstone ( 35 feet thick). The breccia is exposed at Gatacre 
Castle, and the breccia-sandstone in a lane by Gatacre Park Farm 
and on the road from Six Ashes to Bobbington: some of it is slightly 
calcareous. 

The derived sandstone-blocks (Llandovery sandstone, etc.), so 
commonly found in the Sheepwalks breccia in the south, are 
extremely rare at Gatacre in the north. These Llandovery sand- 
stones can be identified from point to point by their fossils, and are 
the most prevalent of the more destructible fragments found in the 
trappoid breccias north of the Abberley and Lickey Hills. 


D’*, regarded as a whole, is a marly series, but it contains one 
definite and nearly continuous breccia-band, which to the south- 
south-east is about 50 feet thick, and occurs near the middle of the 
division. It forms a very prominent ridge, extending for 23 miles 
from Enville to Bobbington. The maximum thickness of D’, from the 
point where it rests upon the trappoid breccia to the north-eastern 
boundary, where it is overlain by the Lower Bunter, is about 150 feet. 

In the south-east, near Enville, where they are seen best, the 
lower marls, forming part of D?, are about 50 feet thick. Farther 
north-west they are exposed at Bobbington Hall, about a mile from 
the north-western boundary of the Permian, where they cover a 
wide expanse of ground, owing more or less to the gentle dip, and 
are seen to contain some intercalated beds of fine breccia. These 
intercalated breccias seem wholly to disappear north-north-west of 
Bobbington Hall. 

The middle and most persistent breccia-band of D? is more con- 
tinuous in the southern portion of the area. The rock-fragments here 
are abundant, and sometimes attain a length of 6 inches. They 
gradually decrease in size and abundance, and, when followed in a 
north-westerly direction to Bobbington, they have become so small 
and infrequent, while the amount of sandy and marly material is so 


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108 CONGLOMERATES OF THE LOWER SEVERN BASIN. _ [ Feb. 1899. 


preponderant, that this zone cannot be separated from the marls 
above and below. 

The highest exposed zone of marls can be seen east of Church 
Gorse, near Enville, where they contain a bed of sandstone. The 
band D? is broadest about a mile south of Bobbington village, where 
the Lower Bunter Sandstones rest upon it. 

A bore-hole put down 4 mile north-east of Bobbington showed 
that the Permian (D) passed through there agrees with the fore- 
going descriptions. Therefore, in the Enville district :— 


(i) The calcareous bands A’, B, & C! retain their calcareous 
character throughout. 

(ii) The calcareous band B' changes from conglomerate to thick 
calcareous sandstone, when followed to the north-north- 
west. 

(ii1) The sandstones and marls, A? & B?, change correspondingly 
in the same direction, from beds partly composed of marl 
to thick layers almost wholly consisting of sandstone. 

(iv) The Middle Permian at the south-eastern end of the 
district is comparatively thin. Possibly the upper part of 
C* has been denuded, and has contributed the rolled frag- 
ments of limestone occasionally found in the Upper Permian 
breccias hereabouts. 

(v) Bands A’, B*, & C! become thicker in a northerly direction, 
while A* & B? attain their greatest development about the 
centre of the district, but at the two extremities they are 
of equal thickness. 

(vi) The marls, C’, become thinner in the same direction as that 
in which the sandy beds below become thicker. 

(vii) The trappoid breccia D' decreases very considerably in 
coarseness and thickness, when followed in a north-westerly 
direction. The sandstones and marls (D*) which overlie 
these breccias, and are also interstratified with them, corre- 
spondingly increase in thickness to the north-north- 
west; but the whole group D, considered collectively, in 
this direction becomes much thinner. | 

(viii) The trappoid breccia also decreases in coarseness in a 

~ vertical direction at any given locality, and insensibly 
passes upward into sandstones and marls. : 


The accompanying table (1) and the restored section (p 
107) illustrate the varying thickness and general characters of the 
Middle and Upper Permian Series of the Enville district. 


la. The Bowhills District. (Pl. XI & Table II, p. 109.) 


Band A! is, for the first mile to the south, a calcareous and 
slightly pebbly sandstone. Near Dodd’s Barn (see Map, Pl. XI) 
7 feet of it is sandstone and 13 feet conglomerate. In the latter I saw 
99 pebbles between 3 and 4 inches long, and one measuring 7 inches. 


1899. ] | [Lo face p. 108. 

| I.—Tue Uri 

fF Beps IN FEET, A, 

Oye at S.S.E. _ | to Between Gatacre and Bob- 
e Sheepwalks, MN, bington, near the north- 
Envitle. Be western end of the district. 
ee ee Relea ot 25 50 

nd Fas 50 Bi 30 

50 70 Ma Sie spose en ee 110 
— 125 — 150 
ee 
20 Marls, breccia, and 
Bi 30 sandstone ......... 35 
—  60'| Brecctal sc .0.cconscu. 20 
225 — 60 

350 200 170 

——— 55555 = SS —————————————— 

35 25 25 

ee Se a eee ese 

» sandstone 10 | Ca 

15 
10 
Calcareous sandstone 50 
20 
— 45 

2 a BE eee 
sandstone, Sd 
equal pro- 90 | Sandstones ............ 110 
Sho co aE Bea 20 

Cy Calcareous sandstone 75 
10 
60 
Sd 
5 
Ce— 75 
BUC es. .cacses 75 
a 
e 
Sandstones and very 
little marl ~{.....0. 50 
Sandstone ............ 20 
330 
500 


> 


Quart. Journ. Geol. Soc. Vol. LV, Feb. 1899.] 


TABLE I.—Tue Upper anp Mippie Peruran or tHe ENviILuE Disrricr. 


Turexness Or Bups IN FEET, ALONG SECTIONS TAKHN PROM Wasr-sourd-wrst To HAst-NoRTH-FAST, 


[Lo face p. 108. 


Zone General Section at S.S.B. From Chidley's Farm Between Lindridge and From Tuckhill to Between Gatacre and Bob- 
Letter. Description by the Sheepwatks, to Gilbert's Cross, Philley Brook, Broadfield Farm, bington, near the north- 
of Beds. Enviile. 1 mile to the N.N.W. % mile to the N.N.W. 3 mile to the N.N.W. western end of the district. 
yz, { Marls, with intercalated | Marls ................ MERU) cosucnyseone 25 Manls Maris ... 
a breccia-bands made up of Breccia-band Breccia-band . 60 Breccia Breccia 
D* |s small material. Marsters trratssceene Mars . 50 Marls Marls ... Warlse esac eee 110 
FE — 125 — 125 
PY ooo, | —. oa —————___., — ——— 
D | Trappoid breccia and breccia- , Marls_ and _breccia- Breccia-sandstone ... 20 Marls, breccia, and 
i sandstone. IBEEO Miariososascas bounce 200} sandstone Breccia . 30 sandstone ......... 3D 
Is ; Breccia — 60/ Breccia ............... 25 
D L Breccia 225) - — 60 
Total thickness of Upper Permian. 350 325 200 170 
Maris. 35 55 aa, 25 25 
Cc ee — ee Se ————— 
re Calcareous sandstone 10 | Caleaveous sandstone 30 | Calcareous sand- Caleareous conglo- 
I stone» jee 10 merate............... 15 
on Caleareous conglo- Soft sandstone .....- 10 
(e Calcareous zone, merate Caleareous _conglo- Calcareous sandstone 50 
Caleareous merate .............04 20 
stone — 45 
a = 380) 
a Soft red and mottled sand- Marls and sandstone, | Sandstones, and some | Sandstones and Sandstones and very 
me stones and marls. in about equal pro- marl at the top ... 20 marls, in about little marl ......... 90 | Sandstones ............ 110 
B \a POMUIONS eee ees 20 equal proportions . 75 
J —— | i SS —— >| 
A Caleareous congilo- Marls and calcareous Calcareous corn- Calcareous sandstone 75 
B fay merate and sand- sandstone ......... 25 stone peteereneet LO, 
SUONE sce weastece 35 | Marls and (more or Calcareous sandstone 60 
Soft sandstone and less) calcareous Fine calcareous 
13) [5 marl sandstone .. 40 conglomerate ....., 5 
A Calcareous g Calcareous sand- — 
A area Lb oe merate and sand- stone and. corn- 
a Calcareous zone. | Conglomerate ......... 75 Ris eraeine ait 40 le stone 50 
H Soft sandstone and | — 1s 
iS WINALL As acetceces 10 | | 
Caleareous conglo- | 
merate and sand- | 
| RON costars aosess a0 | 
== ils 
= — ee 
A? Marls and soft red sandstones. | Sandy marls and | Sandy marls ......... 50 | Marls and sandstone 60 | Marls and sandstone 75 | Sandstones and very 
A SOILS: popsqieccobor 50 | | little marl ......... 50 
AY Caleareous zone. Sandstone ............ 10 | Sandstone ............ 10 | Sandstone 10} Cornstone ............ 10 | Sandstone ............ 20 
Total thickness of Middle Permian. 200 | 300 | 825 320 | 330 
aw | | —e => 
Total thickness of Upper} | 
and Middle Permian, 550 25) 600 520 500 


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499} UL Spoq 944 Jo ssouyo1yy 04} SUIJVI4SNT[] 
“LOIMISIG] STIIHMOG GHL {0 NVINUGG WIddI_ GNV Uadd(~) FBT — TT ATAVL 


110 MR. W. WICKHAM KING ON THE PERMIAN [Feb. 1899, 


For the remaining 24 miles to the north-west the band becomes 
less calcareous, and is devoid of pebbles. 

In Band A’ marls predominate to the south and sandstones to 
the north. 3 

Band B}, fer the first mile to the south, is a calcareous sandstone 
with a few small pebbles. For about 2 miles in the centre of the 
district it is often a massive conglomerate 20 to 25 feet thick 
(Bowhills Barn and Astley Bank), containing many pebbles 3 inches 
long and some measuring 5 inches. For the last mile to the 
northward it is a calcareous sandstone, without pebbles. 

Band B* consists chiefly of sandy marls at the southern end 
of the district, and of sandstones for 3 miles at the northern end. It 
increases in thickness in a northerly direction. 

Band C'.—At and south of Romsley, and at Astley Bank, only 
the basal calcareous sandstone is left. At Bowhills Farm and at, and 
1 mile north-west of, Coton Hall the band is a massive conglomerate, 
20 to 30 feet thick. At Bowhills Farm some of the pebbles are 
84 inches long, many 4 to 5 inches, and some are nearly subangular. 
At Coton Hall the material is finer, but I found one pebble 8 inches 
inlength. For the remaining 3 mile to the north the band is a sand- 
stone, and is less calcareous than at the southern extremity. 

Band C? consists of marls. 

The trappoid breccia D* is left only near Romsley and Coton 
Hall. It contains fragments usually less than 6 inches long. 

The Bowhills Middle Permian is less variable than in the Enville 
district, but the conglomerates are coarser and more prevalent. The 
peculiarities of this district are as follows :— 


(i) The amount of calcareous matrix decreases in a northerly 
direction. , 

(ii) Bands A* & B? are chiefly marls at the southern end, and 
sandstones at the northern. - 

(iii) The materials composing A' decrease in coarseness from 
south to north, while those of B’ & C' are coarsest in the 
centre and finest at their northern extremities. 

(iv) The materials are coarser in the higher calcareous zones. 


16. Warshill and Castle Hill. (Pl. XI.) 


On the side of the Trimpley anticlinal opposite to that on which 
the Bowhills district is situate, and at distances varying from over 
3 miles south-east and 2 miles east from the southern extremity of 
the Bowhills district, there are narrow strips of Lower, Middle, 
and Upper Permian beds at Warshill, and of Upper Permian at 
Castle Hill. 

The Warshill area is small (about 1 mile long and 4 mile wide), 
faulted against Coal Measures, and locally overlain by Lower Bunter 
beds. The lowest Permian rocks visible are red marls, too thick to 
belong to the Middle Permian. ‘These are followed by a calcareous 
Middle Permian band, about 40 to 50 feet thick: it is chiefly a 


- —~ ge Bdee 


Vol. 55.] CONGLOMERATES OF THE LOWER SEVERN BASIN, 111 


calcareous sandstone. At one point, however, near Warshill Top 
Farm, a thickness of 74 feet of conglomerate is exposed, which is 
certainly a portion of this bed: in this section the matrix is less 
calcareous than it is in the other districts. Some fragments in the 
conglomerate-zone are 6 inches long, and fairly angular. This 
calcareous band is succeeded by 25 feet of marls. 

Next follows the Upper Permian (D’), which is represented by 
a trappoid breccia, containing angular fragments, one of which is 
18 inches long, and many at least 6 inches. 

Between Warshill and the Enville district, along the line of the 
Bewdley-to-Enville fault, there are two outlying masses of trappoid 
breccia (D') underlain by marls, but passing upward in one section 
into breccia-sandstone similar to that at Gilbert’s Cross, Enville 
(p. 105). Some of the rock-fragments in this breccia are 9 inches 
long, and many measure 4 inches. The best section is at Castle 
Hill, where the breccia is faulted against Coal Measures to the west, 
and is overlain by Lower Bunter sandstones on the east. 


(2) The South Staffordshire Region (Pl. XII.) 


This region includes those disconnected Permian districts which 
fringe the southern half of the South Staffordshire Coalfield on the 
south, west, and east. The chief of these is the well-known Clent 
Hills district. 


2a. The Clent Hills District. 


Here the Middle Permian covers a tract of country 6 miles long, 
much broken by faults. The Middle Permian strata themselves 
occupy the low ground at the southern margin of the coalfield. 
This low ground is followed to the south by the range of the Clent 
Hills, where the trappoid breccia is grandly developed. 

At Clent Hill the sequence is :— 


Feet. 
Tie 8. Unconformable Bunter conglomerate. 
ee \ pee ites Leip ORAMETEE CID fc aiyi wea. anv cue slaadaeeeennemaeer ent 450 
C?. 6. Marls, and one thin band of sandstone ............ 50 
GE Pade Cornsbomemer neck cseset cede vies cuenta eee ere seeeee oos 10 
Mippue } B*. 4. Marls, and 3 to 4 feet of brown sandstone ...... 100 
EESMANS Para Meda? COPMBLORM OM gets 1.00.20 54.0.3 o~cbce anus ence deadetacsecs 10 
eo a: NEAT ISR RHE Sots 2 sac dete PROIEEO SR wy Se ae ae. 100 
, A’. 1. Cornstone, and more or less Galeaneous red 
on | ee ee 25 
(Lower Permian Red Marls.) 
Total thickness of the Middle Permian ............ 295 


Total thickness of the Middle and Upper Permian '745 


The Middle Permian of the Clent Hills. 


Jukes noticed the Middle Permian of this district, and mentioned 
the existence of cornstones, but no conglomerate. I also have 


112 MR. W. WICKHAM KING ON THE PERMIAN [Feb. 1899, 


failed to find any evidence of the existence of Middle Permian, 
conglomerate here. The three calcareous zones are well shown at 
very many places, and can be followed as distinct ribs. They are 
often crowded with small, rather angular chips and pebbles of pyro- 
clastic rocks, with occasional limestone-pebbles. The fragments, 
rarely, however, exceed 1 or 2 inches in length, the largest that 
I have found being one from Band A’, 4 inches long (Newtown). 
In contradistinction to what takes place in the Enville district, 
A’ is the thickest of the three bands. A’, B’, & C’, following the 
calcareous zones, are mainly composed of marls, but there are a few 
local sandstones, which are, however, relatively insignificant when 
compared with the corresponding bands of the Bowhills-Enville 
district. | : 


The Upper Permian of the Clent Hills 


is made up of the trappoid breccia alone (D'). It occupies two 
sub-districts: (i) that of the Clent Hills proper; and (ii) that of 
Ley Hill, Northfield. The latter will be considered when the 

Warley-Barr district is described (p. 116). , 

(i) The Clent Hills breccia extends from the Lower Lickey 
Cambrian and pre-Cambrian rocks, and ranges north-westward 
along the Clent Hills to Wychbury (see Pl. XI1). The outcrop is 
6 miles long, and at its maximum more than a mile wide. 

This trappoid breccia is coarsest and thickest (450 feet) at 
Walton Hill and Clent Hill. Here the basement-beds are made up 
of a mixture of fine sandy and marly material, and of many small 
fragments of angular breccia, varying in length up to about 
9 inches. About 300 feet above the base there are many angular 
blocks set in a marly paste: some more than 2 feet in length, many 
more than 1 foot, and thousands from 5 to 6 inches. The highest 
en are finer than these, yet some fragments in them are 9 inches. 
ong. 

The breccia of Clent Hill contains many large angular pieces of 
Llandovery sandstone, some of which attain a length of 15 inches. 


26. The Stour Valley District. (Pl. XII.) 


Less than a mile from the north-western extremity of the Clent 
Hills district, the Permian reappears at Chawnhill, near Stourbridge. 
Its outcrop here forms a more or less continuous narrow (4 mile) 
strip, 4 miles long, extending to the vicinity of Kingswinford. 
These beds are faulted against the Carboniferous on the east and 
the Trias on the west, and the strip may be termed (i) the 
Stourbridge-Kingswinford area. The Permian disappears 
for 2 miles at, and north of, Kingswinford along the fault, but it 
reappears between Baggeridge and Sedgley, where its outcrop covers 
a tract between 1 and 2 miles square. This may be termed (ii) the 
Baggeridge-Sedgley area. 


Vol.55.] CONGLOMERATES OF THE LOWER SEVERN BASIN. 113 


The Middle Permian of the Stour Valley District. 


(i) The Stourbridge-Kingswinford area.—About 13 mile 
north of Chawnhill a calcareous cornstone was exposed in a trench 
made some 3 years ago, and in an adjacent field a single band of more 
or less calcareous sandstone is fairly well seen at the present day : 
which band of the three it is cannot be stated. A calcareous band 
again crops out a mile farther north, at Buckpool, and can be 
followed for less than 3 mile: it is a distinct conglomerate, 
between 15 and 20 feet thick. The pebbles are rounded, but some 
are very nearly subangular: they attain a length of 5 inches, 
and are set in a hard, calcareous, sandy base which constitutes 
about half the material of the band. There is not sufficient evidence 
to show whether it is A’, B’, or C. 

After an interval of 4 mile there is a prominent rib, + mile long, 
in the Permian ground. This is made by the outcrop of a calcareous 
band, 35 feet thick, composed of red sandstone, with a few inter- 
calated layers of conglomerate near the base, containing pebbles 
up to 1 inch in length. This band was pierced in the new Bromley 
Colliery. The sinking was commenced on a platform of marls 
which immediately underlies a trappoid breccia (D'), and passed 
through the following strata } :— 


Feet 
Soulesnolyeraivel (OMG ye seete te-acacsscensossnnunncsteemseksseeeneaeee: 23 
Red marl 51 
BR Red rock PPP eee eee HOSES TEHESSEERESSESHEEEH SHEESH E DEE EETEHHE SHES ETEEEESTESE 
Cat-brain Rock (calcareous conglomerate) ..............ceceeeeeee 10 
PRMMIPRC ESA OK Is ons ns ee MEME Hs ciciawed sie teres dein dean MOREE MeReOMAeS « 40 
PICO OE GER AMA PelQO Pepa ins esc nnn avbinn denmspiccbaigagemian cedeuaye i 12 
Red marls, with irregular, slightly rounded nodules of sand- 
GOES je seis cig naa Oe eas clas nee ctr n oie a dea sein calender a 90 


The sinking then passed through a fault from Permian into Coal 
Measures. 

This section is of especial interest in regard to the present enquiry. 
Basing my remarks on field-work here and elsewhere, I consider that 
the 90 feet of red marl is Lower Permian, as so great a thickness 
of marl is not known to occur in the Middle Permian districts 
where conglomerate-zones occur. Again, calcareous sandstone is 
commonly called by miners ‘ Peldon,’ and therefore this 12-foot 
Peldon is probably Band A’ of the Middle Permian. The overlying 
red rock is of the ordinary thickness of A’, with which I am inclined 
to identify it. The conglomeratic horizon may be about 10 feet thick, 
as given in the section, but this at the outcrop is surmounted by about 
25 feet of calcareous red sandstone, and thus the Red Rock and Cat- 
brain Rock together probably constitute B’. There is no third 


1 Geol. Surv. Vert. Sect. No. 49. 


@rs..G. Se Nov 217. r 


114 MR. W. WICKHAM KING ON THE PERMIAN [Feb. 1899, 


caleareous band between B! and the trappoid breccia. Therefore, 
in all probability, Ct has been eroded. 


(11) The BaggeridgeSedgley area.—In this wide Permian 
tract outcrops of the Middle Permian calcareous bands occur. 

A lower band consists of a calcareous sandstone 10 to 15 feet thick, 
with occasional thin intercalated layers of pebbles, of which a few 
are 5 inches long, but as a rule they measure less than 2 inches. 

An upper band is well developed as a massive conglomerate, 
30 feet thick, containing rounded and subangular pebbles, many of 
which are 4 inches long and some 8 inches. This conglomerate 
is coarsest and thickest at the quarry, 28 feet high, on the 
western side of Baggeridge Woods. Though often a conglomerate, 
this upper calcareous zone is sometimes a sandstone, containing 
thin intercalated layers of pebbles which do not, as a rule, exceed 
1 or 2 inches in length. 

That three zones exist in this area is proved by the borehole put 
down many years ago at Goidthorn Hill, near Wolverhampton, 
2 miles north of Baggeridge, which went through the following 
beds * :— 


Feet. 
Soil, marl, and clay (probably Drift)  ...............66- 18 
LightpsamelanacGhee. tv. cate dueiacen lee tees oekl Bee eee 16 
C! ‘Bibley’ (pebbly) or puddingstone-rock ............... 14 
Cl or B { Sott med) feamelen.G dies spexlecunwsensees - ves eee vem eeeee ee 4 
| White, hard (calcareous ?) rock ...........-.0000-00s. 0000s 7 


B? Red, white, yellow, and brown sandstones, etc., with 

thin bands of marl, the latter aggregating 51 feet . 179 

2 Gr BB! * Redinoeke iieeiecaync.c-seesnaccsen- sckese see oaeeeee ee eeeee 6 
BL White ibley” (oebbly) tock “\.5/5.0-...2 ence eee 
A? Red rock and marl (in the proportion of 25 feet of 


samdetonerto 20 feet Ol Marl yl.. s+ 1 cn.etac oes o eee. meee 
A} Light, hard (calcareous?) brown rock .............0+00 22 
Marls,etex(uower Permiam)) was sc-teaccnccsonaceon-tecceen 304 


These beds generally correspond with the Enville Middle Permian. 
The only marked difference is that B' and C’ are thinner than in 
that district, but fuller details as to the calcareous nature of the 
sandstones might have explained this. Band B’ is very thick, as in 
the north-western part of the Enville district (p. 104). 


The Upper Permian of the Stour Valley District 


occurs in the south, at Chawnhill, near Stourbridge. Here is 
found the trappoid breccia (D*), containing angular and subangular 
fragments (some of which are 7 inches long, and many 4 inches), 
and also several pieces of Llandovery sandstone measuring up to 
7 inches in length. The breccia is again exposed in the Stour- 
bridge & Halesowen road. It here consists of small material: the 


1 The details are summarized from the Geoi. Surv. Vert. Sect. No. 50. 


Vol. 55.] CONGLOMERATES OF THE LOWER SEVERN BASIN. lls 


fragments, though still fairly angular, as a rule de not exceed 
2 inches in length, and there is very much marl. 

North and south of Buckpool are good sections of the breccia 
in stream-courses, where 90 per cent. of the material is less 
than 1 inch square. The proportion of marl is very large. The 
largest rock-fragment that I have seen is 9 inches long, and very 
much rounded. Pieces more than 3 or 4 inches long, however, are 
exceptional, and are generally much worn. Several bands of breccia-~ 
sandstone are interstratified with the breccia. 

At Buckpool the exposed thickness of the breccia and intercalated 
sandstones is about 150 feet. The marls C* crep out, and thus the 
thickness can be measured. 

At Clent Hill, as already stated (p. 112), the Llandovery sandstone- 
fragments, embedded in the breccia, are very common, large (up 
to 15 inches long) and angular, while fragments of the same rock 
arein that part of the Stour Valley district which lies north of 
Chawnhill exceedingly rare, small (2 inches long) and rounded. 

In the Baggeridge-Sedgley area there is a little hill, + mile sonth- 
west of Sandyfields, the top of which is an outlier, 1 x 4 furlong 
in extent, of breccia-sandstone (20 to 30 feet thick), like that 
in the north-west of the Enville district. The trappoid breccia has 
ceased to exist. Therefore, when the coarse Clent Hiils breccia is 
followed northward for 8 miles, it is seen to become gradually 
finer, ultimately passing into sandstone. 


2c. The Warley-Barr District. (Pl. XII.) 


It now remains to deal with the north-eastern branch of the 
Middle and Upper Permian rocks that occur on the eastern side 
of the coalfield. This district, from south to north, is 8 miles long, 
ranging from Quinton to Great Barr. It may be regarded as made 
up of three areas :— 

(i) The Warley area at the southern end, commencing at 
Quinton, about 2 miles north of the breccia at Ley Hill, Northfield, 
and extending for more than 2 miles to beyond Langley. It is 
nearly a mile broad, from east to west. The Middle and Upper 
Permian rocks of this area are faulted against the Carboniferous on 
the west, and the Bunter conglomerate rests unconformably upon 
them on the east. 

(ii) The Handsworth area lies north of this, and is situated 
about the centre of the district as a whole. 

(iii) The Barr area is at the extreme north of the main 


district. 


The Middle Permian of the Warley-Barr District. 


(i) The Warley area.—Two calcareous zones may be followed 
in this area, continuously from Brand Hall to Langley, a distance of 


13 mile. The lower and westernmost zone, which I provisionally 
. nen 


116 MR. W. WICKHAM KING ON THE PERMIAN [Feb. 1899, 


identify with B', varies in thickness from 10 to 25 feet. It is 
well developed as a conglomerate, but is sometimes a calcareous 
sandstone. Many of the pebbles are 3 to 4 inches long, and some 
measure 54 inches. The succeeding beds (B*) are mostly marls. 

The second calcareous bed (C') is from 20 to 25 feet thick, is ex- 
ceedingly well developed as a conglomerate, and contains the largest 
fragments known to occur in Middle Permian calcareous zones of 
the Lower Severn basin. One—a subangular block—is 21 inches 
long, pebbles from 6 to 8 inches in length are common, and very many 
measure 5 inches. They are thickly interspersed in an cxtremely 
hard calcareous matrix. 

The marls and sandstones (C*) make no conspicuous show upon 


the ground. Sandstones are well developed in this band at Brand 
Hall. 


Gi) The Handsworth aréa.—The Great Western Railway 
Company are now widening a deep cutting 7 mile west of Hands- 
worth station. This work has laid bare the Upper Permian, with the 
following Permian strata below it: 


Feet. 
Fine calcareous conglomerate ..........esseccscercssseon ees + 
11 Slightly caleareous red sandstone .00........cecsseesecees 15 
oe _ | Fine calcareous conglomerate ......sserrerrereeereeree D 
Puantan? 2, Red sandstone ...........0.... iievages tape ane seu ek ee 20 
B! Massive calcareous conglomerate ..........ceccececeneeee 12 

A? Soft red sandstone, with some marl intermixed ...... 100? 
{Al More or less calcareous sandstone ..............02-2+eeeee 10 
Thickness of Middle Permian ............ - 166 


(Lower Permian marls, with one thin bed of sandstone.) 


The thickness of A’ is doubtful, as there may be a small fault 
between A! and A’: the actual thickness of A’ exposed is 20 feet. 
In B' I found one pebble 8 inches long, and many 3 inches: they 
are far larger than in C'. In the lower layer of conglomerate 
belonging to C! one pebble is 3 inches long, and many 1 inch. 
The upper layer of conglomerate belonging to C* is a very fine 
gravel, the fragments seldom attaining a length of 1 inch. | 

In Sandwell Park, Handsworth, there is a thick calcareous sand- 
stone with a cornstone at the base, containing a few very small 
(1 inch) fragments. It may be seen in the rifle-pits there. 


(iii) In the Barr area a calcareous conglomerate about 15 feet 
thick crops out. The pebbles here are more rounded and much 
smaller (7 inches long being the maximum, and as a rule they do not 
exceed 3 inches) than in the Warley area. 


The Upper Permian, Northfield.—Strictly speaking, it may 
be said that the Northfield breccia is in the Clent Hills district, but 
it lies east of the central area of the South Staffordshire coalfield, 
and I therefore regard it as properly belonging to the north-easterly 


Vol. 55.] CONGLOMERATES OF THE LOWER SEVERN BASIN. 117 


extension of the Upper Permian from the Lower Lickey into the 
Warley-Barr district: for this reason it is described now. 

The breccia (D*) occurs at Ley Hill, and is exposed over a third 
of a square mile. Excellent road-sections occur, showing that 
the basement-beds are made up of fine breccia and maizl, the centre 
of the coarsest fragments, while the upper measures partly consist of 
layers of sandstone and marl. The fragments in the breccia are 
ordinarily very angular: one seen was 21 inches long, a fair number 
12, and many 9 inches long. I have found in this breccia blocks 
of fossiliferous Llandovery rocks, one of which is 21 inches long, a 
few are over 12, and many are 6 to 9 inches long: they are extremely 
angular, and very common. ‘The total thickness of the Northtield 
breccia is about 350 feet. 


Warley.—No Permian breccias are marked on the Geological 
Survey maps in this area. Their existence, however, must have 
been known to the officers of the Survey, for Jukes’ referred to 
‘the angular breccia of the Permian rocks’ at Perry Hill, and 
they have in recent years been traced by Birmingham geologists 
to beyond Langley. 

The Warley breccias commence, at the southern end of the area 
at Perry Hill, as a trappoid breccia interstratified with thick breccia- 
sandstones andsome marls. Here the breccia-group is about 75 feet 
thick, and the breccia-layers lie between sandstones. The fragments 
are sometimes subangular and sometimes rounded, but as a rule 
they do not exceed 2 or 3 inches in length: a piece 6 inches long 
is quite exceptional. Fragments of Llandovery sandstone are rare: 
the few pieces that have been found do not exceed 3 inches in 
length, and the edges are very much worn. Zones of breccia also 
crop out near Brand Hall, which are probably the equivalent of 
the Perry Hill breccia. 

The lowest beds of the series are exposed farther north, in the two 
roads from Bristnall Fields to Langley and Birmingham, where the 
fragmental material is still smaller, and the sand and marl are 
more largely predominant. These lowest beds may be classed as D’, 
on the ground that they form the base of the Upper Permian. 

The succeeding beds are marls, with which thin breccia-sand- 
stones are occasionally interstratified, and they terminate against the 
boundary of the Bunter conglomerate. For the sake of convenience, 
these marls and intercalated breccia-sandstones may be classed as D’. 
There are indifferent exposures of these breccia-sandstones at the 
base of Perry Hill, and a short distance west of Warley. The breccia- 
bands are inconstant, and pass vertically and horizontally into 
marls. The breccias and breccia-sandstones predominate in the 
lower parts of D*, and the marls in the upper beds. The total 
thickness of D} is approximately 200 feet. 


1 Mem. Geol. Surv. 1859, ‘South Staffs Coalfield, 2nd ed. p. 177, & 
also p. J1. 


118 MR. W. WICKHAM KING ON THE PERMIAN [Feb. 1899, 


At Handsworth railway-cutting, still farther north, the trappoid 
zone is only 20 feet thick, and the materials are very fine. It is 
overlain by Permian sandstones (D*). Therefore the coarse breccias 
of Northfield also change gradually to breccia-sandstones and marls 
in a northerly direction. 


VIE. ConcLUsIONS BASED ON THE VARIATION IN THE COARSENESS OF 
THE MATERIALS. 


Having now completed the description of the changes in the 
Middle and Upper Permian rocks, it remains to compare South-east 
Shropshire and South Staffordshire, as follows :— 


(i) In both regions there is a middle series of calcareous zones 
interstratified with sandstones and marls, preceded by thick 
marls, and succeeded by breccias. ‘This triple series suggests 
the probability that the calcareous zones of the two regions 
correspond in age. 

(11) In both regions, A? & B? are chiefly marls in the southern 
parts of the regions described, and sandstones in the northern. 

Gi) In South Staffordshire b' & C’ are coarsest and thickest in the 
centre (from south to west). But in these central portions 
they are most conglomeratic, thickest, and the pebbles largest 
towards the E.S.E., a direction that differs but slightly 
from the 8.8... source indicated by the South-east Shropshire 
region. ‘The materials of the Middle Permian in other areas 
towards the north-west (Alberbury), however, may come from 
a different direction. we 

(iv) The trappoid breccias of both regions (@) are coarsest and 
thickest at their southern extremities, and (6) show an 
upward transition into marls. 


VIII. Tue PEBsres oF THE Miporz Permian ConeéLoMERATES. 
(Tables IIT & IV-) 


At all the localities cited in the. foregoing pages, where the con- 
glomerates of the Middle Permian occur in place in the calcareous 
zones, | have made a careful examination of the pebbles in the 
conglomerates, and have endeavoured to fix the geological horizon 
of the rocks of which the several pebbles are composed. Many 
ot these fragments are fossiliferous, and their age can be estab- 
lished with more or less approximation to certainty. Others are 
unfossiliferous, but the age of many, if not all, of these may be 
determined by comparison with rock-types that occur in place and 
the age of which is already known. 

The rocks so far found in these Middle Permian calcareous 
zones are aS follows :— 

(1) Arncuman. These comprise the following :— 

Finely laminated hornstones, or halleflintas (green, 


Vol. 55.] CONGLOMERATES OF THE LOWER SEVERN BASIN. 119 


black, or red).—The hornstones occur generally in the Middle 
Permian conglomerates and cornstones, in greater or less quantity, 
as very small chips and pebbles. They are abundant in the 
Clent Hills district and common in the Warshill area, while 
they seldom occur in these conglomerates in the other districts 
described. 

Grey and purple-banded felspathic grits are common 
in the cornstones of the Clent Hills district, and in the conglo- 
merates of the Warshill area, but seldom occur in the conglomerates 
of the other districts. 

Coarse and fine volcanic tuffs and agglomerates are 
very rarely found in these conglomerates in any of the districts 
described, except Clent Hills and Warshill. 

These Archean fragments embedded in the Middle Permian cal- 
careous zones constitute in the Clent Hills district the bulk of the 
material, in the Warshill district 40 per cent., and in the remaining 
areas rarely more than 5 per cent. 

The hornstones, grits, tuffs, and agglomerates can be paralleled 
more or iess certainly with similar Archean or Uriconian rock- 
types, which occur in place as rock-masses at Barnt Green, the Lower 
Lickey Hills, and Nuneaton on the south and east, and at the 
Wrekin and Cardington Hills of Shropshire on the north and 
west. 

Vein-quartz pebbles commonly occur in the Middle Permian 
cornstones of the Clent Hills district, and are also found in small 
quantities in the same conglomerates in other districts. 

Conglomerates of doubtful age, in the form of pebbles, have 
been rarely found in these Middle Permian conglomerates. These 
conglomerate-pebbles are hard and compact, and chiefly made up 
of vein-quartz and pyroclastic rocks. 

(2) Camprran.—Rounded pebbles of greyish-white quartzite are 
fairly abundant in the Clent Hills district, but are not common in the 
other districts. These quartzites are comparable with the Cambrian 
quartzites which occur in place as rock-masses at Nuneaton and the 
Lower Lickey on the south-east, and at the Wrekin on the north- 
west. 

(3) Orpovictan pebbles have not been found hitherto in these 
Permian conglomerates. 

(4) Luanpovery Sanpstones.—I have found, in Band C' of the 
Bowhills district, a piece of fossiliferous brown sandstone containing 
fthynchonella nucula, Rh. defleca, and Mytilus mytilimeris. This 
sandstone is chiefly made up of washings from white quartzite. 
Another yellow and fossiliferous piece of sandstone from the same 
band and locality is also made up of washings from quartzite and 
quartz, and contains Mytilus mytilimeris. A piece from the top part 
of Band B', at Enville, is a brown, micaceous, fossiliferous sandstone 
containing Tentaculites annulatus. Several unfossiliferous fragments 
of the foregoing lithological types have been found in Band C’ of the 
Enville district. Llandovery sandstones are, however, extremely 


20 MR. W. WICKHAM KING ON THE PERMIAN [Feb. 1899, 


rare. These pebbles agree precisely in lithological character with 
the Llandovery sandstones seen in place at the Lower Lickey and 
Great Barr, and the fossils mentioned have been found at the 
Lower Lickey. 

(5) Wootnorr Limestone.—A piece of bluish-grey limestone from 
Band C’ of the Warley area contains a Woolhope fossil, Stropho- 
mena arenacea, and lithologically resembles part of the Lower Lickey 
Woolhope Limestone (5 miles away). In Band C’ of the Bowhills- 
Enville district a few pebbles occur of a similar bluish-grey lime- 
stone, one of which contains that fossil of wide range Strophomena 
rhomboidalis, and another contains Euomphalus sculptus. There are 
moreover in the Bowhills-Enville, Stour Valley, and Warley-Barr 
districts a few coarsely crystalline yellow limestone-pebbles, one 
of which (from Bowhills) again contains Strophomena rhomboidalis. 
Part of the Woolhope Limestone in place at the Lower Lickey is a 
precisely similar, coarsely crystalline, yellow limestone. Pebbles of 
Woolhope Limestone are, however, rare in these conglomerates. 

(6) Wentock Limestone.—T wo distinct types of Wenlock Lime- 
stone occur in these conglomerates: (a) the dolomitic limestones ; 
(6) the non-dolomitic limestones. 

(a) The Dolomitic Limestones.—Some of these limestone- 
pebbles are firm, compact, and finely crystalline, and in colour red, 
reddish-brown, pink, or yellow. Others are coarsely crystalline, 
and are usually red or pink. 

In the coarsely crystalline varieties the amount of red coloration 
varies so considerably, that sometimes, unless closely examined, 
they may be mistaken for the ordinary grey Wenlock Limestone. 

These dolomitic limestones contain (among other fossils) Strecklan- 
dinia Uirata, Orthis Bouchardu, Rhynchonella cuneata, Glassia com- 
' pressa, and Pterinea planulata, 

The dolomitic limestones, as Murchison observed, occur in greatest 
abundance in Bands B' & C' in the Bowhills district, in ©! in 
the Enville district, and in the calcareous band of the Warshill 
area. In these bands in the South-east Shropshire region the 
dolomitic limestones constitute at least half of the pebbles, while 
in the Stour Valley and Warley-Barr districts they rarely amount 
to one-tenth. 

Dolomitic limestones of the same age as, and of rock-types strikingly 
similar to those of these pebbles in the calcareous conglomerates, crop 
out at Abberley Hall,’ and in many parts of the Abberley-Malvern- 
May Hill range. Phillips called them the Magnesiferous, and on 
other pages the Dolomitic Wenlock Limestones. Mr. T. H. Waller 
kindly analysed for me a specimen found im situ at Woodbury Hill, 
and it contains 3°12 per cent. of magnesia. He analysed another 
from farther south, at Collins Green, between Abberley and Malvern, 
which contained 18°31 per cent. of magnesia; while a third from 

1 The exposure referred to is the broad band marked, on the Geol. Surv. 


maps, evidently by a clerical error, as Aymestry Limestone. In the Memoirs 
it is correctly designated Wenlock. 


Vol. 55. ] CONGLOMERATES OF THE LOWER SEVERN BASIN. ie 


Wenlock Edge, in Shropshire, yields only 0°31 per cent. of magnesia. 
Specimens more recently found in the Abberley Hall grounds are 
apparently more magnesiferous than that from Woodbury Hill 
which has been analysed. The specimens from May Hill contain 
28°3 per cent. of magnesia. . 

These Abberley Hall dolomitic Wenlock Limestones (in place) 
are nearest to the Bowhills district (8 miles), where pebbles of 
similar dolomitic limestones occur in the Permian conglomerates in 
great abundance (50 per cent.). On the other hand, the Abberley 
Hills are 16 to 25 miles distant from the South Staffordshire region, 
where the dolomitic limestones constitute less than 10 per cent. of the 
pebbles found in the Permian conglomerates. 

(6) The Non-dolomitic Limestones.—These are the ordi- 
nary type of Wenlock Limestone, coarsely crystalline, grey, passing 
through finely crystalline greyish-white to compact non-crystalline 
types. Up to the present no satisfactory fossils have been found in 
these, partly because the fragments are so small; but lithologically 
they are the same rock-types as the Wenlock Limestones now ex- 
posed in the centre of the South Staffordshire Coalfield at Dudley. 
These non-dolomitic limestones constitute from 20 to 30 per cent. 
of the pebbles in the Stour Valley and Warley-Barr districts, while 
in South-east Shropshire they are comparatively scarce. 

We are thus confronted with the striking fact that the dolomitic 
Wenlock Limestone-pebbles in these Permian conglomerates prevail 
in the South-east Shropshire region, and the non-dolomitic Wenlock 
Limestones abound in the Stour Valley and Warley-Barr districts ; 
and that, close to the aforesaid Shropshire region, dolomitic Wenlock 
Limestones are in place, while in the Stour Valley and Warley-Barr 
districts the non-dolomitic Wenlock Limestones of Dudley are in 
place. 

(7) Downton Sandstone occurs as a greenish coarse-grained rock, 
in place, at Abberley. A pebble of the same type, containing un- 
identifiable fossils, has been found in the calcareous conglomerates 
of Bowhills, 8 miles to the north. 

(8) Passage-BED To Otp Rep Sanvstone.—At Abberley and Trimp- 
ley a peculiar yellow claystone occurs in place, near the junction of 
the Downton Sandstone and Old Red Sandstone; and precisely the 
same lithological type occurs in the conglomerates of the Bowhills 
district, 8 miles north-west of Abberley and 2 miles north-west 
of Trimpley. This is evidently the rock to which Mr. G. E. Roberts 
alluded in the same terms as I have done (see p. 98). 

(9) Orv Rep Sanpstonz.—This formation has a wide outcrop on the 
Trimpley anticlinal, and is partly composed of a close, fine-grained, 
evenly-bedded, purplish, hard and compact sandstone. Precisely 
similar pebbles occur in the calcareous conglomerate of Warshill, 
which is close to the edge of this anticlinal, and in the calcareous 
conglomerate of Bowhills. JI have not found Old Red Sandstone 
anywhere else. This apparent absence of Old Red Sandstone 
pebbles is consistent with the evidence obtained from two borings 


122 MR. W. WICKHAM KING ON THE PERMIAN [Feb. 1899, 


near the Clent Hills, which proved that the Coal Measures rest 
directly upon the Silurian passage-beds and that at the Lickey 
the Carboniferous beds rest upon the Woolhope. 

(10) Carzontrerovus Limesronts.—Pebbles of dolomitic Carboni- 
ferous Limestone occur generally in the Permian calcareous conglo- 
merates of both regions. Many are silicified, and some are more or 
less cherty. They are firm, close-grained and compact, and of 
various colours—black, white, yellow, and dark greenish-grey. It 
is extremely difficult to find any identifiable fossils in these pebbles, 
but they are full of crinoid-stems. I can, however, state that they 
contain (among others) Streptorhynchus crenistria, Chonetes har- 
drensis, Productus Deshayesianus, Pr. costatus, Athyris gregaria, 
| A, planosulcata, A. Royssii, and Codonaster trilobatus. 

These pebbles of Carboniferous Limestone are rarest in the 
Bowhills and Warshill districts. They commonly occur in Band Bt 
of the Enville district, but are rarer in Band C’ of that district. 
In the Stour Valley and Warley-Barr districts they are more 
abundant than elsewhere, constituting at least 60 per cent. of the 
pebbles in the Permian conglomerates. The cornstones of the 
Clent Hills district contain only a small proportion of Carboniferous 
Limestone-pebbles. 

The discussion of the probable source of the Carboniferous Lime- 
stone-pebbles will be deferred, until all the rocks found in these 
Permian conglomerates have been mentioned. 

(11) Carzonirerous Sanpstones.— Yellow sandstones occur in 
place in various parts of the Wyre Forest (as, for example, 
Bewdley and Tenbury railway-cutting) and South Staffordshire (as 
near Chawnhill). Fragments of them are found more or less in 
the Permian conglomerates in both regions, especially in Band A’ 
of the Bowhills district, and in the conglomerates at Warshill and 
in the Stour Valley and Warley-Barr districts. 

(jreen micaceous sandstones occur in place, near Bewdley, in the 
Wyre Forest coalfield, and I have found pebbles of a similar green | 
micaceous sandstone in the conglomerates of the Bowhills district, 
4 miles to the north-west. These Carboniferous sandstones are, 
however, comparatively rare. 

I also found, in the Warshill Permian conglomerate, a pebble 
derived from an older, very compact conglomerate. ‘The component 
materials are chiefly white (Silurian?) limestone. The compact 
Carboniferous conglomerates of the Wyre Forest coalfield also 
contain fragments of limestone. 

(12) Lower Permian Sanvsrones.—Red coarse sandstones, which 
can be distinguished from the Old Red Sandstones by their peculiar 
tint (for they sometimes contain a certain amount of yellowish- 
white material), and by their softer and looser texture, occur in 
place within 14 mile of the Bowhills district at Alveley, and in the 
South Staffordshire region near Hunnington. Pebbles of red 
sandstones, comparable with these, occur generally in the Middle 


[To face p. 122. 


OSITION OF THE PEBBlig, 


c = common, 


‘abp 
migqnop fo sagvseuopbuop 


‘saqvuaumopbbn pun sffng 
I2UDIIOR BUY PUD ASLMOK) 


‘s70ub agdand pun hat 


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ea | | 


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“OU0ISPUDY PIX PIO 


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"SOU0ISPUBY UNIUdaAT “anoT 


NM 


r 


r 


MN 


as well as Carboniferous Limestones, 


oy 


Quart. Journ. Geol. Soc. Vol. LV, Feb. 1899.) 


TABLE ILI.—Composrtion 


[ a= abundant. 


OF THE PEBBLES 


© = common, 


Rzcron. 


———$——____| 


SourH-rAsT 
SHROPSHIRE. 


SourH 
STAPFORDSHIRE. 


THE MIppLE PrrMIAN CoNGLOMERATES. 


[To face p. 122. 


* Silurian, as well as Carboniferous Limestones, are sometimes finely crystalline yellow or white. 


r = fairly rare. s = are. | 
a LIMESTONES. 
a 
8 R 
s $ = A = 
z = s Doromrric Won-Dorourrie ‘ S — | Seis 
S < z t S SILURIAN. SrLURIAN. x 3 iS $ s3s|°s 
S = Ss 8 > S S$ 2 = Ses || Ss 
= 2 Se, Ss 5 R&R Ss 
Disrrzer. Locanrres. a S S § 2 g = Ss 5) 3 & 8 SS tS |S 
S yn $ = So: & S&S me |] nh feta s S S ~ 28 S 
BY SOUS oa lees Ses |= (S818 18 188 S s = S| ss] 2 
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Set eee es | & |S | 8S] S$) 58] 38 eile] sig SS 
a | 2 is | ek So] 8% /8.)/ 28 | as] es] Fs S18 i S| Sei 8 TSsis 
5 x $s S SS) || = Ses RS || ASS 2) 2 = e 
aa See PSSST ERE TSE Soy 2 8 | 8 See] & boo) cs 
S Sy Ss SSS SAN Ss 3 S| 85 $ 8 ss 3s Ss] 8 
ails |S |S | & | § | 88] 82) 88/ 88188] ss8]s8)] § | Ss |e] s &=| & | ee] ss 
» SoS ATs Is ie (Ss IS 1S" 18 Sy St |S is SS Ss 
( Compton ...... ee Bt s sP ‘ a a a r | c s s s s s s 
| |: _——— |_| | a 
Hnville ......... 1 | 
| {| Four Ashes .........| C c ¢ r ca) an : s c s S s s 
| (| Six Ashes ............| ©? s s ; ¢ c Y a G s s s s s 
| 
Dee | ee 
( | 
| Dodd’s Barn... At i Y s ae c c r ¢ ¢ s r 5 s s s 
4 al — _— 
! 
Astley Bank... B s Ss Yr Ss c C ¢ Q a c s s 8 s s s s 
Blows hush eyes 4 _ — — — 
| Bowhills Farm...... OF r Ss ¢ ¢c ¢ a a s s s Ss s Ss s s s 8 
| Coton............... (oh “ c c c c a Ss a Ss Ss 
Warshill ...... P m 8 ¢c 8 Yr Ss a a es Y a © a 8 
(|Clent Hills... Hunnington and -’ . " 5 s c c c ¢ c 
St. Kenelm’s ... a 
( Wordesley ......... iP ae a a a s s a Y S Ss s 
| Stour Wraibllay 2 Baggeridge ......... Ce Y $ a a a s A a a S s Ss 8 8 
| SIAL BIEN ooo coconnonan: on a ae a a a s s s aes 8 8 S 
: ° s 5 8 
| iNVarleyannesnes ree B} s 5 a B) a i Ss r c Sf Ss s s Ss 
: sP Ss Ss s 
| Warley .. (Oy r s a a a r aH s a a 
Warley-Barr... 4 _——— ——_ —_ =r —— 
. Ss Ss s s 
| Handsworth ......... B s a a wf 8 ” 
‘ a s s 
( Great Barr ......... ? s 8 a s Y Q 8 s Y 
X 


Voles5.| CONGLOMERATES OF THE LOWER SEVERN BASIN. 123 


Permian calcareous conglomerates of both regions, save only the 
Clent Hills district. They are found in greatest abundance in 
Band <A! of the Bowhills district, and in Bands B' & C' of the 
Stour Valley and Warley-Barr districts, but are never very 
common. 


Table III (facing p. 122) illustrates the general distribution and 
comparative abundance of the chief lithological varieties of the rocks 
which occur in these Middle Permian conglomerates. 

The fossils so far found in the limestone-pebbles described are 
enumerated in Table IV (pp. 124,125). Davidson’s monograph on 
the British Fossil Brachiopoda has been used in identifying them, 
unless otherwise stated. 


LX. Generat Conclusions. 


All the rocks that have been mentioned occur in place in the 
Midlands, within a reasonable distance of these Middle Permian 
conglomerates, with one exception. This is the Carboniferous 
Limestone, a geological formation which hitherto has not been met 
with in the immediate neighbourhood of the Middle Permian areas 
that have been described. 

The nearest point where the Carboniferous Limestone occurs is at 
the Titterstone Clee Hills, 7 miles south-west of the Bowhills district. 
But, so far as I have examined that limestone, there are few pebbles 
in the Middle Permian that could be safely referred to it; for, while 
the latter are mainly dolomitic, all the rock of the Clee that I have 
seen is apparently non-dolomitic. Carboniferous Limestone also 
occurs in place at the Wrekin, 15 miles north-west of the Enville 
district and 30 north-west of Warley. The Wrekin limestones in 
at least a few localities are dolomitic, contain locally abundance of 
chert, and in some respects they agree with the rock-fragments in 
the Permian conglomerates. The drift, however, of all the material 
composing the Permian calcareous conglomerates, except the Car- 
boniferous Limestones, has been from the south and east; whereas 
the Carboniferous Limestones at the Clees and the Wrekin are to the 
north and west. But the intermixture of the Carboniferous Lime- 
stone-pebbles with the other material suggests a common source for 
the two. Is it not possible that these pebbles also were derived 
from the south and east, from a sheet of Carboniferous Limestone ? 
Curiously enough, at the opposite ends of a line running north-east 
and south-west through the regions described, from Ashby de la 
Zouch into South Wales, we find the Carboniferous Limestone in 
place—namely, at Grace Dieu on the north-east, and at the edge of 
the South Wales coalfield about the same distance to the south-west. 
In both these localities the Carboniferous Limestone is dolomitic. 
If patches of this dolomitic limestone were in place at other points 


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126 MR. W. WICKHAM KING ON THE PERMIAN [Feb. 1899, 


along this line at the time when the Middle Permian rocks were 
being laid down, then all the pebbles in the Permian conglomerates 
might have come from this common source.’ 

The source from which the fragments composing the trappoid 
breccia were derived may not have been the same as that from which 
these Middle Permian conglomerates were brought, and, so far as I 
know, no one has attempted to prove the contrary. But, on the 
other hand, if the direction of travel of material was approximately 
the same in both cases, the two sets of deposits would mutually 
interpret each other and afford a strong confirmation of any theory 
which would supply a reasonable explanation of both. It has been 
seen that the trappoid breccias are thickest and coarsest in the 
southern parts, and thin away to the north. With the exception of 
the Carboniferous Limestone-pebbles, no fragments occur, in either 
the Permian calcareous conglomerates or the trappoid breccias 
described, of any rocks that are not in place in the Midlands, and 
these rocks all lie to the south and east. If the source of this 
material be sought west and north-west of the South-east Shropshire 
and South Staffordshire regions, it is true that the Welsh Border 
(Wrekin, etc.) will supply the Carboniferous Limestone-pebbles, but 
not the characteristic lithological types of the dolomitic Wenlock 
Limestones of Abberiey nor the peculiar yellow Woolhope Lime- 
stones of the Lickey type. 

Furthermore, the Ordovician is well developed along the Welsh 
Border. But the Ordovician has afforded no fragments to the 
Middle Permian conglomerates or to the trappoid breccias of the 
regions described, and the larger fragments of Llandovery sand- 
stones found in the trappoid breccias are composed of materials 
identical with those in place at the Lower Lickey, namely, Cam- 
brian quartzite and Archean grits and hornstones, showing that 
they were laid down on a Cambrian and pre-Cambrian floor. 

It is a remarkable fact that these Permian calcareous con- 
glomerates consist practically of pebbles derived from the pre- 
Permian down to the Woolhope Limestone; they are, except near 
the Lickey, ‘ limestone-conglomerates.’ On the other hand, the 
later trappoid breccias of the Upper Permian are composed chiefly 
of Archean materials, especially near the Lickey, with, in certain 
localities, many fragments of highly fossiliferous Llandovery 
sandstones and beach-rocks, and small quantities of Woolhope 
Limestone. The presence of the rocks down to the Woolhope. in 
the Middle Permian limestone-conglomerates, and of the rocks 
at and below the Woolhope in the Upper Permian trappoid breccias, 
could be explained easily if the area which furnished the material to 
these Permian limestone-conglomerates had been eroded down as a 
whole through the Carboniferous Limestone to the Woolhope during 
Middle Permian time, while in the succeeding trappoid-breccia 


} Compare Mr, H.'T. Brown’s conclusions, Quart. Journ. Geol. Soc. vol. xlvy 
(1889) p. 27. 


Vol. 55. CONGLOMERATES OF THE LOWER SEVERN BASIN. 127 
period subaerial denudation cut through the Woolhope Limestone 
and Llandovery sandstones deep down into the Archean Series. 

If the ridges ranging along the east and south of the regions 
herein described afforded this material, the special association of 
pebbles and breccia could be explained; for the sequence of the 
rock-materials, with the doubtful exception of the Carboniferous 
Limestone, is that which would be afforded by these ridges as 
shown by the Nuneaton, Lickey, and Abberley successions. The 
occasional intermixture of fragments older than the Woolhope 
(especially close to the Lickey) would be accounted for easily if, while 
the ridges as a whole were arranged in a tine from north-east to 
south-west, each individual member had its greatest length from 
south-east to north-west, and if some of them were locally denuded 
during an earlier period down to a lower plane than the Woolhope.? 

I hold that the Middle and Upper Permian materials have been 
derived from the ‘ Mercian Highlands,’ now more or less buried under 
the Trias of the Midlands, south and east of the regions described. 

This special line of research was originally suggested to me by 
Prof. Lapworth, and I thank him for continued encouragement and 
assistance. 


EXPLANATION OF PLATES XI & XII, 


Prats XI, 


Map of the Upper and Middle Permian of the South-east Shropshire Region, 
on the scale of 1 mile to the inch. 


Prats XII. 
Map of the Permian Areas in the Lower Severn Basin, on the scale of 4 miles 
to the inch. 
Discussion. 


The PrestpEnT, in congratulating the Author, read the following 
extract from Geikie’s ‘Memoir of Sir A. C. Ramsay,’ p. 228, which 
had been pointed out to him by Mr. Teall and seemed to have con- 
siderable bearing on the paper. It refers to remarks made by 
De la Beche in 1855 on Ramsay’s Permian Glacier :—‘ As to 
the scratching of breccia-fragments,—'tis their nature to—a 
tumble-down house will give plenty of them; and then as to old 
localities for the fragments, independently of not having cakes 
which have been eaten, who the dickens, in such places, can say 
what rocks are beneath the sprawl of New Reds?’ 

Prof. Sottas recalled the interest with which in earlier days 
geologists listened to Ramsay’s eloquent expositions on a Permian 
ice-age, and, witheut committing himself to any opinion, pointed 
out the line of argument which a supporter of Ramsay’s views 

1 See paper on the Halesowen Upper Coal Measure conglomerates, claimed 


to be derived from ridges at the Lickey, then eroded down to the Archzxan, 
in Birm. Nat. Hist, & Phil. Soc. Journ. vol. ii, p. 118. 


128 CONGLOMERATES OF THE LOWER SEVERN BASIN. [Feb. 1899. 


might fairly follow. The Author had proved that the breccias thicken 
out and become coarser towards the south-south-east, and though, if 
water had been the agent in their deposition, this would be the direc- 
tion in which their source lay, the exact opposite might be the case 
if they had been brought by ice, which frequently deposits its coarser 
material in thicker masses towards its termination. Given an origin 
towards the north and west, then the source of the Carboniferous 
limestone-fragments, which outweigh those of Silurian age, became 
clear. 

Prof. Hutt and Prof. Lapworts also spoke. 

The AvtHor stated, in reply to Prot. Hull, that he had been 
engaged in the investigation of the Permian rocks for 9 years, and 
had dealt with the literature. It is inconsistent with Ramsay’s 
north-western theory that the materials are coarsest to the south- 
east and.east. The pre-Cambrian fragments in the Permian breccia 
do correspond with those on the Welsh Border, but in recent years 
similar rocks have been found at the Lickey and Nuneaton, ete. to the 
south and east. The post-Cambrian fragments agree wonderfully 
well with those locally an situ, but differ from those that occur on 
the Welsh Border. 

Prof. Hull had also referred to the alleged ‘glacially’ striated 
fragments. Previous writers have stated that they are slickensides. 
The Author had found that these slickensides occur inside and out- 
side the fragments, and also on the matrix. Furthermore, the 
rarity or abundance of these slickensides varies proportionately with 
the amount of earth-movement to which each part of the breccia 
has been subjected. amsay’s own specimens actually support the 
last-mentioned observation. 


Geol. Soc, Vol. LV, Pl. XI. 


} 


MAP OF 


OF 


UPPER & MIDDLE PERMIAN 


S.E. SHROPSHIRE REGION. 


<4 
aN 
@ Yer 
py SN 
Zk 
Wea. 
AYES ONS 
Ks 


: 2, f [Paste “S\N 
—— EXPLANATION — By Be ao Gathare\: 
ZX Beal) Newbasira hae, Re ae 
Foul Sevan esti eee ee see yell I TINS 
Upper { me where it is Marl....--------- aa 7) * ' Boe Os ‘ 
Saas TE STAN 5 
re KY CANS 
F < » i o\\9} 
Z District-* 7X cay yo 
rae) a, Annan 
E -7 Dodds 
a Barn ea 
Ce) \ 
a ‘| ven 
‘A - ee 
a) f: \\ * 
7 \ 
oo t 
7 
<, » 
, 
fa ? 
7 


X\\Bepbington 
‘\\e 


& PO eat \ 
x ht .35/Castle Hill 


— 


Quart. Journ. Geol. Soc, Vol. LV, Pl, XI. 


MAP OF 


UPPER & MIDDLE PERMIAN 
OF 


S.E.SHROPSHIRE REGION. 


—— EXPLANATION — 


VEU, hemse teen ease = 
Upper W?2 where it is Marl... 


Permian | W\where itis Breccia 
A! B!« C! where they are 
Calcareous Conglomerate. 
A! B14 C! where they are 
Caleareous Sandstones. 
Permian } 52 ¥%%« ©? Sandstones & 
Marls between the Calcar 
eous zones 


Cee 
N 
“N 


Middle 


RG 


Arrows show dips 


Za if 
Sheonwaika | DiSMRICH 


. <x 


ie i \ : = Compton 


7 
District-~ 
ca 


/ 

“I / 
ped 9 7 
/ 
oY 0 
UpperArley YS if /Horscley 
4 j,/ Farm 
| AS if & 
gs 9 Y 
= 


Scale: 1 tnch = 1 niile. 


Warshill 
District 


Quart. Journ. Geol. Soc. Vol. LV, Pl. XII. 


Dudley 


1 
v\ ; 
mm Coaltield 
Vey 
Ne 
VEEA 
Buckpool \::\ 
vn 
Xa 
“A 
ot 
Stourbri 
Pedmore'= 
? 
R { A 
4 I 
\ 
\ 
\ 
N 
X 
XN 
Scale: 4 miles = inch. 
Extracted from Prof. Lapworth’s 
ia, Geological Sketch-Map of the Birmingham district, 
Bs with additions. 


AREAS IN THE LOWER SEVERN BASIN. 


Quart. Journ, Geol. Soc. Vol. LV, Pl. XII. 


Dudley 


Coattield 


Wyre Forest 


44 
Coalfield £7 Wassuill 


r 


/ 
U 


“Bewdley 


Scale: 4 miles — 1 inch. 


[3 Permian areas Extracted from Prof. Lapworth's 
CayAbberley trappoid breeefa. Geological Sketch-Map of the Birmingham district, 
E= Silurian and older rocks. with additions. 


MAP OF THE PERMIAN AREAS IN THE LOWER SEVERN BASIN. 


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Vol. 55.] GEOLOGICAL STRUCTURE OF THE SOUTHERN MALVERNS, 129 


8. The GuotocicaL Srructure of the SourHern Matverns, and of 
the Apsacent District to the Wust. By Prof. T. T. Groom, 
M.A., D.Se., F.G.S. (Read December 7th, 1898.) 


[Puates XITI-XV.] 


Contents. 
Page 
ellis) OF (CaS SPOINAA GY 2 ono s:n'n oo, «nn aeein ele janet debe erecta easene tues 129 
MPR GLEHEMa SELUCLUG OF PMO AVOCA ......ccceconescvecuscuscseransussoecese+ocnes 130 
abba eN aly Ort ANE O...c...62 c+ soassasoenscenicedesneedecupheany seeacesooeerce 131 


(1) Raggedstone Hill. 
(2) Midsuinmer and Hollybush Hills. 
(3) The Central Depressions in the Hills of the Southern Part of 
the Range. 
(4) The Hollybush Pass. 
(5) The Gullet Pass. 
(6) Chase End Hill. 
(7) Confirmatory Evidence from the more Northerly Portions of 
the Range. 
(8) Theoretical Explanation of the Structure of the Southern 
Portion of the Malvern Range. 
MTG Cnt CRUE AC oe yin. oexch- due vince enaisnaayeetavastaddeaues cba nonce: 157 
(1) The District of White-leaved Oak, ete. 
(2) The District around Fowlet Farm. 
(3) The District around Bronsil. 
Vo the May Hill Sandstone Escarpment  ......c0..icccsccoeednccsascersuness 166 


I. HistoricaAL SUMMARY. 


Fastity accessible, situated in a charmingly picturesque country, and 
marking some of the most interesting phases in the evolution of 
the British Isles, the Malvern Hills have now for nearly 80 years 
formed the subject of geological investigations, and have ever yielded 
new facts of interest and importance. 

Leonard Horner! described the Malverns as a granitic mass in- 
truded into the associated strata. Murchison’ regarded the chain 
as essentially of igneous origin, though including ‘Silurian’ beds 
altered by the intrusion. Phillips, in his masterly work on the 
district,> maintained that the Lower Paleozoic strata associated 
with the range had been deposited against the crystalline rocks. 
Holl,* regarding the range as probably composed of pre-Cambrian 
metamorphosed sedimentary and igneous rocks, described the Cam- 
brian and Silurian beds as overlapping the metamorphic series. 

Mr. Rutley ° considers that the gneissic and schistose rocks of the 
Malverns are a series of altered tuffs, grits, sandstones, and volcanic 


* Trans. Geol. Soc. ser. 1, vol. i (1811) p. 281. 

2 «The Silurian System,’ 1839, pp. 417 e¢ segg. ; ‘ Siluria,’ 1854, pp. 92 et segg. 

3 Mag. & Journ. of Sci. vol. xxi (1842) ; Mem. Geol, Surv. vol. ii (1848) pt. i, 
pp. 66 ez segg. & pp. 125-126. 

* Quart. Journ. Geol. Soc. vol. xxi (1865) pp. 89, 92, 97 et sega. 

° Ibid. vol. xliii (1887) p. 508. 


Q.J.G.8. No. 218. K 


130 PROF. T. T. GROOM ON THE GEOLOGICAL [May 1899, 


and other igneous rocks. Dr. Callaway,’ on the other hand, regards 
the former series as metamorphosed plutonic rocks, chiefly granite 
and diorite, and compares them with the Archzan Series of Primrose 
Hill in Shropshire. Thesame author ? recognized the volcanic series 
of the Herefordshire Beacon, and correlated it with the Uriconian 
rocks of Lilleshall Hill in Shropshire. The Herefordshire Beacon 
rocks have subsequently been studied by Green,’ and by Messrs. 
Rutley,*’ Harker,’ and Acland.° 

During the past year the present writer’ has maintained that 
the Malvern and Abberley Hills are the basal wrecks of an old 
mountain-range which arose during Coal Measure times. 


Il. GENERAL STRUCTURE OF THE ARBA.® 


The area which constitutes the subject of the present communi- 
cation includes the southern end of the Malvern Range, as formed 
by Midsummer, Hollybush, Raggedstone, and Chase End Hills, 
together with the districts of Coal Hill, Pendock’s Grove, White- 
leaved Oak, Fowlet Farm, and Bronsill, which lie immediately west 
of the range. This area is one of the most interesting in the 
Malvern district, because here the upheaval of the Paleozoic strata 
has been greater than elsewhere, and thus the Cambrian beds have 
been brought within the sphere of denudation: whereas, along the 
rest of the range, the Silurian are the lowest Paleozoic rocks that 
come to the surface. 

The main axis of the joint mass of Midsummer and Hollybush 
Hills, like that of Swinyard Hill (from which it is separated by the 
Gullet Pass), runs about north and south ; that of Raggedstone Hill, 
which is bounded on the north by the Hollybush Pass, and on the 
south by the lower part of the ‘ Valley of White-leaved Oak,’ runs 
about north-west and south-east ; while Chase End Hill runs from 
north-east to south-west. On the east, these hills are bounded 
abruptly by the Trias, along an undulating line of fault. On the 
west, the lower parts of the slopes are formed almost exclusively by 
a flanking series of highly-inclined and much-dislocated Cambrian 
strata. 

At a short distance to the west of this southern part of the 
range is a half-lyre-shaped escarpment, well-marked for the greater 
part of its course, and formed by the May Hill conglomerates and 
sandstones. 

Between this escarpment and the Malvern Range is a partially- 
enclosed basin, or tract of generally lower ground, largely occupied 

1 Quart. Journ. Geol. Soc. vol. xxxvi (1880), vol. xliii (1887), vol. xlv (1889), 
& vol. xlix (1893). 

2 Ibid, vol. xxxvi (1880) pp. 5386 et segg. * Ibid. vol. li (1895) pp. 1-8. 

4 Tbid. vol. xliv (1888) pp. 740 ed segg. 

5 « Petrology for Students,’ 1895, pp. 55, 148, etc. 

6 Quart. Journ. Geol. Soe. vol. liv (1898) pp. 556-562. 

7 Rep. Brit. Assoc. 1898 (Bristol), p. 873. 

8 Throughout this paper the signs M100, M 108, ete. refer to localities 


corresponding to numbers in the map (Pl. XIII), and to specimens collected 
at those localities. 


Vol. 55.-] STRUCIURE OF THE SOUTHERN MALVERNS. Let 


by the Cambrian shales. For descriptive purposes this may be 
spoken of as the ‘ Western Tract.’ Its surface is greatly diversified, 
owing to the presence of a number of intercalated bands and in- . 
trusive bosses of andesitic basalt and diabase, as well as by the 
inclusion of several faulted blocks of May Hill Sandstone. These 
masses form a series of continuous or interrupted ridges or eleva- 
tions, standing out more or less clearly from the surrounding lower 
ground. Some of the gentler elevations are capped or flanked by a 
stratified Drift of local origin. The district is, moreover, brokev up 
by two small valleys, one running from the Hollybush Pass west- 
south-westward, and the other from the village of White-leaved 
Oak south-westward. 

The tract is partly under cultivation, and partly used as pasture- 
land; much of it towards the south, however, is occupied by 
woodland. The soil, in accordance with the varied petrographical 
character of the rocks, varies greatly in character, but is for the 
most part of rather poor quality. 


Ill. Tae Matvern Raner. 
(1) Raggedstone Hill. (Figs. 1-7.) 


It is proposed to examine first the structure of Raggedstone Hill, 
because it is here that the mutual relations of the various rock- 
masses are best shown. 

The hill is approximately triangular in outline, and is divided 
throughout its length by a curved depression running from north to 
south right across its centre, two distinct summits being thus formed, 
each of which attains a height of over 800 feet (see Pl. XIV). 
North of the summits the depression broadens out north-north- 
eastward, and forms a hollow known as Winter Combe. On the 
south, too, the depression widens, as it curves south-eastward. 

This depression marks a line of dislocation, as already shown for 
part of its course by Holl,’ and by Mr. Rutley.* The former points 
out that the character of the rocks and the strike of the schists 
differ in the two halves of the hill. In Mr. Rutley’s map this 
fault is represented as terminated by a transverse fault on the south ; 
but I shall in the sequel give evidence to show that it probably 
runs the whole length of the depression. 

That portion of Raggedstone Hill which lies east of the depression 
is formed by a mass of Archean rocks: this, according to the two 
authors named, is divided by faults into three main blocks. I 
think it probable that a fault cuts off a fourth component block, 
forming that part of the eastern side of the hill nearest the large 
quarry on the Hollybush Pass. I have not attempted, however, to 
represent these faults on the map (Pl. XIII), believing that the 
structure of the Archean mass can be satisfactorily ascertained only 
after detailed mapping and petrographical study of the complex, 


* Quart. Journ. Geol. Soc. vol. xxi (1865) p. 75. 
 Tbid. vol. xliii (1887) p. 488. 
K2 


132 PROF. T. T. GROOM ON THE GEOLOGICAL [May 1899, 


such as is not attempted here. I have, therefore, contented myself 
with representing on the map (PI. XIII) the observed strikes and 
- dips of the gneissic series, 

These dips, as indicated Fig. 1.—Diagrammatic plan of the strue- 
in the map, frequently ture of the north-western corner of 
show a marked relation Raggedstone Hill, and of the south- 


to the direction of the western part of Midsummer Hill. 
axial fault, the schists 


generally dipping away HGS E 

at a considerable angle ie tio Rem 
towards the eastern side, hy f Le it oe hae 
and the strike conform- xsl UM 1 M Etieve “Sch 
ing more or less closely Meee 


to that of the curving 
fault. 

The exact position of 
the line of junction with 
the Trias is difficult to 
determine, as no expo- 
sures of the latter are 
seen close to the hill. 
It must, accordingly, be 
fixed chiefly by the cha- 
racter of the slope; for 
here, as elsewhere along 
the range, the steep slope 
formed by the Archean 
rocks gives place lower 
~ down to the much gentler 
slope of the Triassic 
area. The character of 
the soil occasionally af- 
fords assistance. 

The western half of 
the hill is more complex 
in structure. The higher ie 

ortions are formed, for ee 
the most part, of a strip : a/ hs 
of gneissic, schistose, and [Bedlein|6 inches f aaa 


massive rocks, whichmay B.Sh. = Black Shale. Q.=Quartzite 


: Hb.S. = Hollybush Sand- (black). 
Ee eee te road stone (outcrops). | Sceh.= Archean. 


in the Hollybush Pass to Hb.S'.= Grey Hollybush | FF.=Faults. 
that in the ‘ Valley of Sandstone. 


White-leaved Oak.’ The Hollybush Sandstone and Black Shales are 
North of the contour- traversed by igneous rocks (Jgn., cross-hatched). 

line of 800 feet the 

gneissic series is not exposed, and its presence is revealed only by 

débris and by excavations, but schists and gneisses appear to have 

been observed along the line by Holl.’ The series can, however, be 


1 Quart. Journ. Geol. Soc. vol. xxi (1865) p. 75. 


hee a (17a) 


finn 


Vol. 55.] STRUCTURE OF THE SOUTHERN MALVERNS. 133 


readily traced south-south-eastward from the summit of the hill, 
and may be seen on the roadside near the bottom of the ‘ Valley 
of White-leaved Oak’ (across which these rocks appear to pass) to 
terminate against the gneissic and schistose series of Chase End Hill. 
The Archean rocks are, accordingly, not completely cut out in 
the manner supposed by Phillips,‘ but are reduced to a narrow 
isthmus. 

At the top of the hill the strike of the series is generally from 
north-east to south-west, but elsewhere it shows a clear relation to 
the boundaries of the strip, the prevailing dip being easterly, as on 
the eastern side of the hill (see map, Pl. XIII). 


The western slope and the north-western corner of Raggedstone 
Hill are formed almost exclusively by the Hollybush Sandstone, 
together with an associated series of igneous rocks. The junction 
of the sandstone with the gneissic series can be determined with 
fair accuracy fora considerable part of its course. On the northern 
slope of the hill it is difficult to follow, since, unlike the majority of 
important junctions in the district, it is indicated by no depression, 
_ or marked change in the angle of slope of the surface ; but south of 
the summit its position may be determined within narrow limits, 
although it is actually visible only in the large quarry near White- 
leaved Oak. The relations of the two series on Raggedstone Hill 
have been regarded by Holl? and Symonds *® as proving uncon- 
formable superposition of the sandstone upon the older series ; but 
careful examination indicates that the junction is a fault, both in 
the northern and southern portions of the hill. 

The Hollybush Sandstone in the former locality appears to dip, 
on the whole, uniformly west-north-westward, at an angle varying 
from 40° to 43°; the outcrops (see fig. 2, p. 134), plotted out ac- 
cording to the character of the slope, indicate that the beds abut 
against the gneissic series; while the long dyke is abruptly cut off 
towards the south-east in a way which is best explained by a fault. 

Here the sandstone shows a broken anticline, the summit of 
which forms a small sharp ridge running parallel to the junction. 
The axis of the anticline rises south-south-eastward. ‘This fold 
was seen and figured by Murchison,’ though he gave it a cone of 
erystalline rock, for the existence of which, however, I have seen 
no evidence. At the southern end of the quarry the fault is nearly 
vertical (see fig. 4, p. 136). 

On the east, a series of glossy sericite-schists dip on the whole 
east-north-eastward ; near the junction they are thrown into a series 
of small folds, pushed over towards the south-west, and with axes 
rising towards the south or south-south-east. The sandstone is 
separated from the schists by a few feet of brown, greyish-white, 
or green sandy limestone, dipping, like the adjacent sandstone, at a 


Mem. Geol. Surv. vol. ii (1848) pt. 1, p. 25. 

Quart. Journ. Geol. Soc. vol. xxi (1865) pp. 89, 92, 97 et segg. 
‘ Records of the Rocks,’ 1872, p. 34. 

‘Silurian System,’ 1839, p- 418. 


Pr OW 


Fig. 2.—Sketch-map of the neighbourhood of the large quarry at 
White-leaved Oak, showing the relations of the Hollybush Sand- 
stone and the gnerssic serves. 


Fig. 7. 


Scale: 19% inches =1 mile, 


N 
Arrows show direction of dip. 


tS 
AOS 
HAN SUR 


=) 


rs 


wil 


IS: 
NY 4 
aN 


<3 
Se 


wv 
ter 
os 


; 


o% 

IN 

San 
rs 


oh 


‘BSUEe 


Z— 


= ~ 
| ease 


[The shaded portion is theoretical ; the strike of the schists is represented 
by the strong rippled lines. ] 


— 


Vol. 55.] GEOLOGICAL STRUCTURE OF THE SOUTHERN MALVERNS. 135 


high angle south-westward. Farther away from the schists, at the 
top of the quarry, the flaggy beds bend over, so as to dip eastward. 

North of this point, and about halfway down the slope of the 
quarry, the sandstone and schists, together with their plane of 
Junction, all dip west-south-westward at an angle of 25°. 

Still farther north-westward (figs 6;%p: 136) the sandstones at 
the top of the quarry dip west-south- westward. At an angle of 30°, 
but halfway down the slope, the beds suddenly turn over, and become 
nearly vertical. These are separated from the Archean rocks by a 
thin faulted block of impure brown limestone, followed by a few 
feet of the flaggy sandstone. The plane of junction of the latter 
with the schists dips west-north-westward at an angle of 30°. The 
schists are vertical, striking towards the west-north-west. 


Fig. 3.—Section across the junction of the schists and Hollybush 
Sandstone, at a point south-south-east of the large quarry at 
W hite-leaved Oak. 


Bee TSS 
S W ea . 
e . ¢ es okve 
‘ ——— * 
‘ 7 ~ 
7 ’ 


See, 
~~. 
. 
- ~ 
s-.8 = 
- 


agg - sn 
Hollybush Sandstone Schists 


e 
° e. 
2 me ee 2 
ne 
Rosa oe oe 


Massive 
Hollybush Sandstone 


[Scales: horizontal, 26 inches = 1 mile; vertical, perhaps rather less. | 


Combining the relations seen in these three sections (figs. 4—6, 
p. 136), the facts may, I think, be explained by supposing the 
existence of another anticlinal fold of sandstone, faulted against the 
Archean massif, and against the more southerly-situated anticline, | 
and overthrown ds the north- east, as indicated by the dotted 
lines in the sections. 

At the extreme northern end of the quarry (fig. 7, p. 136) the 
sandstone again dips west-south-westward at an average angle of 25°; 
while the schists dip irregularly, in a nearly opposite direction, at a 
very steep angle. 

About halfway between the points at which sections 6 & 7 were 
taken, more massive and darker beds of sandstone at the top of the 
quarry dip east-north-eastward at an angle of 60°. These beds are 
probably the same as those exposed in the two small quarries in the 
sketch-map (fig. 2), and are separated by one or more faults from 


Fig. 4.—Section across the south-western part of Raggedstone Hill. 
S.W. 


N.E. 
uarry 
F ' 
t 
’ 
\ 
cae : 
ee ees ee eee See Es p 
Black Shales F Hollybush Sandstone, Schists 


with Limestone (L) 


Fig. 5.—Section across the south-western part of Raggedstone Hill, 
a short distance north-west of that shown in fig. 4. 


S.W. 
Quarry 


i FN (fa) FT ial (2 
thet oltfofopedit- 
PP ath piste as 


A 
Black\ 


Schists 
Shales F Hollybush Sandstone 


Fig. 6.—Section across the south-western part of Raggedstone Hill, 
rather to the north-west of that shown im fig. 5. 


S.W. 


Is NE. 
t 
ee 
F we 
1 be QV 
oye eee ze 
ot aE Decent SS 
lack ® Hollybush Sandsten ’ Schists 


Shales f. F F 
[Scale of figs. 4-6: 38 inches = 1 mile.] 


Fig. 7.—Section of the northern part of the large quarry at 
White-leaved Oak. 


w.s.w. at \ 
iW 


Schists ; Schists 


[Scale: 76 inches = 1 furlong.] 


‘Vol. 55.] GEOLOGICAL STRUCTURE OF THE SOUTHERN MALVERNS. 137 


the more thinly-bedded flaggy and shaly series seen in the sections 
hitherto described. 

Summarizing the relations of the schists and peadeeones seen in 
the large quarry, it may be stated that the plane of junction is a 
fault, showing a close but variable relation, on the one “hand, to the 
strike of the schists, and on the other to that of the sandstone. 
Prof. Lapworth informs me that the schists are of the nature of 
mylonites. 

The dips of the sandstone beyond the limits of the quarry are 
shown by arrows in the sketch-map (fig. 2, p. 134). 


To the south the Hollybush Sandstone appears to be entirely cut 
out by faulting, and the Black Shales brought into direct contact 
with the gneissic series. Almost everywhere else along the line of 
fault the sandstone itself seems to be in direct contact with the 
gneissic series, but on the slope due west of the summit (see fig. 1, 
p. 132) débris of a quartzite and conglomerate may be found. In 
these I have obtained numerous specimens of Kutorgina cingulata 
and other fossils. This fossiliferous rock is not now exposed in 
place, but Symonds’ states that it was formerly quarried, and could 
be seen to dip at a high angle beneath the Holiybush Sandstone. 
At a point not far from the summit, and about 35 yards south of 
the outcrop of the diorite in the gneissic series, is a shattered 
quartzose rock, forming a tump near the end of a line of bushes 
and trees running up the slope. I have little doubt that this is the 
Hollybush Quartzite modified in the vicinity of the fault, but no 
fossils were obtained from it. 

The general relations which have been indicated between the 
gneissic series and the flanking Cambrian deposits are, I think, 
incompatible with the idea, suggested by Holl, of an unconformity 
combined with rapid overlap, and can be adequately explained only 
by a fault. This is in harmony with the opinion expressed by 
Dr. Callaway,” though no evidence in favour of this view was adduced 
by him. 

The practically straight course of both the northern and siaeheths 
parts of this fault, as they cross the contour-lines, suggests that the 
fault is on the whole nearly vertical, although, as seen in the large 
quarry to the south, it has by no means everywhere a plane 
surface. 


The relations of the sandstones forming the north-western corner 
of Raggedstone Hill, to those constituting the narrow strip on the 
south-western flank of the hill, are not clear. The dip in the former 
locality, as already indicated, is at a moderate angle towards the 
west-north-west, while in the latter case it is usually south-westerly 
or west-south-westerly, at a higher angle, and is occasionally 
reversed. Judging from the occurrence of quartzite at several 
points along a line running down the slope (fig. 1, p. 1382) and from 


1 «Old Stones,’ 2nd e1. (1884) p. 24. 
2 Geol. Mag. 1879, p. 219. 


138 PROF, T. T. GROOM ON THE GEOLOGICAL [May 1899, 


the broken character of the more southerly strip, it is highly probable 
that a transyerse fault separates the two series, and this view fits in 
better with the theoretical explanation of the structure of the hill 
given on p. 153. 

The pentagonal block forming the north-western corner of 
Raggedstone Hill is crossed by a thick dyke of andesitic basalt. 
This, being a durable rock, stands out, and forms the western face of 
a prominent rib running down from near the summit of the hill to 
cross the road in the Hollybush Pass. It is not an interbedded 
lava, as supposed by Holl,’ but is clearly intrusive, for it crosses the 
outcrop of the sandstone-beds in a marked manner, as shown in 
fig. 1 (p. 132). Where it is intersected by the road, it is seen to 
dip westward at an angle of about 30°. 

Along its western boundary, the Hollybush Sandstone is succeeded. 
for most of the length of the hill by the Black Shales. The junction 
with these also is a fault; for, although at one spot the Hollybush 
Sandstone has a reversed north-easterly dip, elsewhere along the 
line of junction the dip is south-westerly, while that of the Black 
Shales, wherever they are clearly exposed, is north-easterly. 


(2) Midsummer and Hollybush Hills. (Figs. 8-10.) 


The portion of the range formed by these twin hills shows, in 
some respects, a structure similar to that of the Raggedstone. The 
joint mass is quadrangular in shape, and the two hills are separated 
on the south by a deep depression in which were formerly situated 
an old British town and what were apparently three old British 
reservoirs (Pl. XV). The northern portion of the mass is divided 
into three parts by two depressions, one of which, running east- 
north-eastward, forms the northern boundary of Hollybush Hill ; 
the other runs northward. 

The bulk of the two hills is composed of a mass of gneissic, 
schistose, and massive rocks, probably traversed by a number of 
faults, as indicated by sudden variations in the strike of the folia. 
On the whole, the mass exhibits a markedly plagioclinal structure, 
the foliation usually showing no relation to the boundaries, a 
feature in which these hills differ from Raggedstone and Chase 
End Hills. But in the large quarry at the southern end of Holly- 
bush Hill the schists dip east-south-eastward at a high angle. 

The Archean Series is bounded on the east by the Trias, along 
a line of fault. The breccia marking this fault-line, and consisting 
of fragments of Archean rocks and Triassic sandstone, is exposed in 
an old quarry on the roadside (M 191). To the north a transverse 
fault brings the gneissic series against that of Swinyard Hill, with 
its flanking deposits of May Hill Sandstone. The lower part of 
the western slope of Midsummer Hill, for the greater portion of its 


' Quart. Journ. Geol. Soc. vol. xxi (1865) p 
? [Omitted unintentionally from the map, Par "sm I.) 


Vol. 55. ] STRUCTURE OF THE SOUTHERN MALVERNS. 139 


length, is composed of Hollybush Sandstone, but the north-western 
corner of the hill consists of May Hill Sandstone. 

The Hollybush Sandstone is separated from the Archean Series 
by a northerly prolongation of the fault that runs down the north- 
western corner of Raggedstone Hill. This fault forms no feature in 
the landscape, and its apparently straight course across the contour- 
lines indicates that it is practically vertical. That the junction is 
really a fault follows from the dip of the sandstone behind the 
cottage on the northern side of the Hollybush Pass; the beds here 
strike directly towards the gneissic series. The Hollybush Quartzite, 
moreover, as on the western slope of Raggedstone Hill, appears to 
be absent along by far the greater part of the line of junction, but 
at one point a brecciated quartzite (M 173 a),! in places impregnated 
with heavyspar, is exposed. This has, so far, yielded no fossils, but 
its close lithological resemblance to the Hollybush Quartzite, as seen 
in hand-specimens and under the microscope, shows that it belongs to 
the Hollybush Series. Ata distance of 1 or 2 feet from this rock 
the Hollybush Sandstone is exposed, apparently dipping at an angle 
of 20° west-north-westward, and abutting against the quartzite, 
from which it must, accordingly, be separated by a fault. 

The May Hill Sandstone at the north-western corner of the hill 
was evidently noted by Phillips, who remarks that there are traces 
of ‘Caradoc’ Sandstone between the Obelisk and Midsummer Hill.” 
Débris from this patch are abundant, and furnished a variety of 
fossils, among which the following were recognized :—Stricklandinia 
lens, Sow., Str. lirata, Sow., Pentamerus oblongus, Sow., P. glo- 
bosus, Sow. (?), ‘ Petraia,’ crinoid-stems, corals, etc. 

The beds are exposed in place, only at the extreme north- 
western corner of the patch, where the dip is 45° eastward. 

These May Hill Beds are separated from the gneissic series by a 
well-marked band of hard conglomerate and quartzite, which I 
would propose to call the Holiybush Conglomerate and 
Quartzite. It can be traced from the bed of the stream flowing 
down the Gullet Pass, in 2 south-south-westerly direction, along the 
western slope of the ridge of gneissic rocks forming the northern 
extremity of Midsummer Hill. Its junction with this series is not 
marked by any depression or change of slope, but can be indistinctly 
seen in the road, where, though somewhat irregular, it dips on the 
whole east-south-eastward at 80°: the fault is, therefore, reversed. 
Both series can also be seen in the bed of the stream. The junction 
with the May Hill Sandstone is not exposed, but is indicated by 
a small depression, along which runs a footpath from the road. 
The conglomerate and quartzite are well seen in a small quarry 
(M 170) near the roadside, where the beds dip north by west at 
32°; some of the layers here are crowded with fragments or whole 
shells of Kutorgina, etc. At a point farther south the dip is 
apparently north 30° west at about 15°; still farther south (M 366) 


1 (‘73 a’ on the map, Pl. XIIT.] 
2 Mem. Geol. Surv. vol. ii (1848) pt. i, p. 54. 


140 ‘PROF. T. T. GROOM ON THE GEOLOGICAL [May 1899, 


the dip appears to be east-south-easterly at from 60° to 72°, while 
in the bed of the stream it is north-westerly at 25°. The strip 
is accordingly composed of beds which, in the south striking appa- 
rently parallel to the line of outcrop, in the north strike on the 
one hand against the gneissic series, and on the other against the 
May Hill Sandstone; it must, therefore, be bounded by two 
approximately parallel faults. 


Fig. 8.—Section across the northern slope of Midsummer Hiil. 
W. Midsummer Hill E. 


Fa 


1F 


[Scale: 3 inches = 1 mile.] 


FF= Faults. c=Lower beds of May Hill Sand- 
pete Ni aniG stone, with Ctenodonta, Lin- 
Rip { gula, ete. 
d=Beds of May Hill Sandstone, b=Hollybush Quartzite and Con- 
with Stricklandinia. glomerate. 


a= Archean. 


Towards the south the conglomerate cannot be traced as far as 
the northern limit of the Hollybush Sandstone; it is probably cut 
out by the meeting of the two faults which bound it. Moreover, 
a continuation of one of these faults probably truncates the Holly- 
bush Sandstone and the Black Shale which occur on the western side 
of Midsummer Hill. To the north, both the gneissic series and the 
conglomerate are cut off by a transverse fault running east and west 
down the Gullet Pass. 


Fig. 9.—Section of dyke on the northern side of Hollybush Pass. 
W. ENG : x 


Bayer 7. = E, 


Basalt Dyke ae ' Hollybush Sandstone 
[Approximate scale: 1 inch = 11 yards.] 


The extent and disposition of the Hollybush Sandstone on the 
western slope of the hill are difficult to make out, as exposures are 
few, but careful examination makes it evident that the sandstone 
forms a somewhat narrow strip, bounded on the west by a fault 
which is approximately parallel to that on the eastern side of the 
strip. The position and direction of the fault can be determined 
by the junction along the middle of its length with the Black Shales 
on the west, and by the abrupt change in the strike and dip of the 
sandstone along the road from Hollybush to Upper House Farm. 
The fault is marked here by a slight depression running down a 


Vol. 55.] STRUCTURE OF THE SOUTHERN MALVERNS. 14] 


cottage-orchard. The dip behind the cottage is to the west of south 
at 75°, while immediately to the west the dip is west-south-westerly 
at 33°. It may be noted that the strike of the beds of the southern 
portion of the strip is almost straight across the length of the latter ; 
while close to the quartzite (M 173 a) the sandstone dips at 20° west- 
north-westward, and strikes obliquely across the strip. In all proba- 
bility a transverse fault cuts off the southern portion of the strip. 

The south-western corner of Midsummer Hill is formed by a 
quadrangular patch of Hollybush Sandstone, invaded by a number of 
small intrusive masses of andesitic basalt. It stands out as a well- 
defined small hill, on the northern bank of the stream running 
down the Hollybush Pass. It is bounded on all sides by faults ; of 
these (four in number) that on the west, which separates it from a 


Fig. 10.—Section across Midsummer and Hollybush Hills. 


Mid- 
summer Hollybush 
Hill. 


ae h 


[Scale: 43 inches = 1-mile.| 


FF= Faults. d=Black Shales (Cambrian). 
h=Trias. ¢ =Hollybush Sandstone. 
g=May Hill Sandstone. b=Hollybush Quartzite. 
f=Grey Shales (Cambrian). a= Archean. 


e=Igneous rocks in Black Shales. 


faulted block of May Hill Sandstone, is difficult to trace. The dip 
of the Hollybush Sandstone in this varies from 33° west-south- 
westward to 40° west-north-westward, and thus approaches closely 
that noted on the other side of the Hollybush Pass. 

That intrusive mass of which the relations are seen most clearly, 
is well exposed in a small quarry on the road from Hollybush to 
Upper House Farm. ‘The dyke is there observed to dip eastward, 
at an angle of 45° (see fig. 9). The intrusive character of this 
dyke was recognized by Phillips." 

Four of the faults to which reference has been made enclose 
another quadrangular area (see map, Pl. XIII), the southern part 
of which at least, and, as I believe, the whole, is occupied by Black 
Shales, here, for the most part, baked grey by an associated series 
of andesitic basalts. The dip of these shales at the south-western 
corner of the patch is 25° to west by south; while near the 
south-eastern corner it is about west 37° north at 56°. One of 
the intrusive masses forms a well-marked, rounded boss, but the 
majority appear to be small sills. 


1 Mem, Geol. Surv. vol. ii (1848) pt. i, p. 53. 


142 PROF, T. T. GROOM ON THE GEOLOGICAL [May 1899, 


The general relations of the Archzan rocks of Raggedstone, 
Hollybush, and Midsummer Hills to their flanking deposits, and the 
mutual relations of the latter one to another on the slope of the 
hills, have now been considered; and it has been shown that these 
hills consist of a number of faulted blocks. Since the rocks of 
the formations concerned are everywhere separated by faults, 
it follows that no proof of the relative order of superposition 
of these formations can be given from the area considered. 
Nevertheless the axial position of the gneissic series, and the 
prevalent order of proximity of the remaining formations, clearly 
suggest the generally received order of superposition in the district. 
The conglomerate and quartzite are found only in contact with the 
eneissic series; the Black Shales are generally more remote from 
the axis; while the Hollybush Sandstone occupies an intermediate 
position, and the superposition of the May Hill Sandstone on the 
shale series is fixed by evidence from other parts of the area described 
in these pages. 


(3) The Central Depressions in the Hills of the Southern 
Part of the Range. (Figs. 11-15.) 


It was long ago observed by Phillips* that the Malvern range 
was on the whole a single chain of hills, but that certain hills, 
such as Raggedstone Hill and the joint mass formed by Mid- 
summer and Hollybush Hills, showed two summits placed side by 
side. Holl pointed out later’ that in the case of Raggedstone Hill 
the eastern and western sides differed in structure and lithology, 
and he recognized the existence of a fault running down a part 
of the depression between the two halves. This deduction was 
confirmed by Mr. Rutley.? Apart from these, ] am unaware of any 
observations bearing on longitudinal structural differentiation of the 
Archean axis. 

Now, the magnitude of the depressions which occur along the centre 
of Raggedstone Hill, and between Midsummer and Hollybush Hills, 
appeared to me too great to be explained by a simple fault. I 
therefore suspected the existence of softer or more easily denuded 
masses in the middle of the gneissic series, introduced, possibly, by 
earth-movements. A careful examination of the hollows showed 
that this conjecture was correct. 

The hollow on the southern side of Midsummer Hill (see Pl. XV) 
is bounded by two steep slopes, and has a somewhat sharply-defined, 
rather flat bottom, sloping down towards the south-south-west. 
The gneissic rocks descend to the level of this floor. The floor 
itself is covered with turf, and no rock is exposed in place: but 
excavations made in former days, during the construction of the 
three old British reservoirs, and of the trench of the camp at the 


1 Mem. Geol. Surv. vol. ii (1848) pt. i, pp. 9, 11, 26. 
2 Quart. Journ. Geol. Soc. vol. xxi (1865) p. 74. 
® Ibid. vol. xliii (1887) p. 488, figs. 1 & 2. 


Vor 55. STRUCTURE OF THE SOUTHERN MALVERNS. 143 


top, resulted in the throwing out of some of the rocky bed of 
the floor. The débris from the middle reservoir consist chiefly, 
or solely, of fine-grained quartzite and conglomerate (M 169), 
which can be unmistakably recognized as belonging to the Holly- 
bush Quartzite series. Immediately above the reservoir, frag- 
ments of purple Llandovery Sandstone and Grit were numerous 
(M 168): these occurred as far up the hollow as the uppermost 
reservoir, where the fragments were most numerous (M 167). 
Typical purple Llandovery Sandstone was also found close to the 
trench at the top of the hollow (M 166). 

Pieces of Llandovery Sandstone (M 174), including a large block 
with Stricklandima l- 
rata, Atrypa reticularis, Fig. 11.—Diagrammatic section, showing 
Pentamerus (2), Orthis, the junction of Archean and Llandovery 
Leptena (?), and Tentacu- strata in the Hollybush Pass. 
lites anglicus, were found 
at the top of the hollow W. ffx FE. 
at the northern end of 4 
Hollybush Hill, and 
other fossiliferous frag- 
ments were obtained in 
the trench immediately 
above it. Phillips re- 


x 
x) 


Xx 
marks* with reference oe 
fomethis’ hill :—-“It is ae 
somewhat singular to x x 
find pieces of fossilifer- XA 
ous Caradoc sandstones ; _ 
amongst the loose masses ae 
of the camp-mounds.’ ‘ x 

Now, there are no ve 
rocks on the higher parts x x 
of the hill from which  --.. sf op efolal|yx © * 
fese fragments could e “ ° TICS 9 Gay AY Ok ees 
have been derived by Ce eek. 
gravitation, and it is ee ae 
hard to believe that their 
position can be due to a FF=Fault b=Green and yellow 
do lower levels, more Pecompone pur- | sandy haley, 

) ple sandy rock. with traces of 
particularly as there is, d= Yellowsandstone; crinoids; 18 
so far as I know, no proof it Bee ee guches ao 
of the existence of glacial nds Hae a meh Ys ke 


conditions over the Mal- 
vern Range. The only possible explanation is, I think, that slips 
of the Hollybush Conglomerate and May Hill Sandstone occur 
beneath the turf and debris; and that the hollow, in part at any 
rate, owes its existence to the excavation of the easily-denuded 
materials of these formations (see fig. 10, p. 141). 


* Mem. Geol. Surv. vol. ii (1848) pt. i, p. 28. 


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Vol. 55.] GHOLOGICAL STRUCTURE OF THE SOUTHERN MALYERNS. 145 


This conclusion was confirmed by the discovery, made later, of 
a patch of May Hill Sandstone in place, embedded in the heart of 
the Malvernian gneissic series, at the extreme southern end of the 
hill, and along what is evidently the same line of dislocation. 

Along the northern side of the road in the Hollybush Pass, 
exactly opposite the 4th milestone from Ledbury, may be seen the 
junction of this strip with the gneissic series. ‘The May Hill Beds 
of the patch apparently consist chiefly of a purple grit, which 
is exposed only in a weathered condition, but may be reached by 
excavation. The width of the zone along the road is perhaps as 
much as 50 yards. A little more than this distance west of the 
milestone, rocks of the gneissic series were again reached by 
excavation. Jig. 11 (p. 143) represents the relations seen opposite 
the milestone. The dip of the sandstones is predominantly west- 
north-westward at 60°. The junction is clearly a fault, with an 
undulatory surface, which runs about north and south, and, for the 
most part, dips eastward at an angle of about 80°. 

The evidence from the hollow on the southern side of Ragged- 
stone Hill is of a similar nature, but less obtrusive, fragments other 
than those of the gneissic series being rare. Immediately above the 
road I found a large block of Hollybush Conglomerate (M 177), 
and at the level of the north-western margin of the two small 
copses in the hollow (M178) another piece of Hollybush Con- 
glomerate, together with large fragments of purple Llandovery grit, 
were obtained. At an intermediate point fragments of Hollybush 
Sandstone were found; these, however, possibly came from the 
ridge bounding the western side of the hollow a little higher up, 
the crest of which is formed by the sandstone, but no such origin 
can be assigned to the other two kinds of rock. In the upper part 
of the hollow no fragments can be found, except débris from the 
Archean rocks of the slopes, and in all likelihood no Paleozoic 
rocks are present at this point, the strips which occur lower down 
having probably a lenticular shape. An important feature of this 
hollow is the practical certainty that a line of dislocation runs 
down it, as first shown by Holl.’ 

In the large hollow on the northern side of Raggedstone Hill, 
known as Winter Combe (see Pl. XV), the proofs of the inclusion 
of Paleeozoic rocks in the Archean Series are more satisfactory. 
Along the western slope of the hollow there is a distinct outcrop, 
for some distance, of Hollybush Conglomerate (M 164), which dips 
between west and west by north at 40°; that is, straight towards 
the gneissic series, from which it is, accordingly, in all probability, 
separated by a fault. This band of conglomerate forms a low 
rounded ridge. Fig. 14 (p. 146) represents a section drawn across 
it to scale, with a length down the slope measured in yards. 

The Archzan rocks are not exposed at this point, and the position 
assigned to them is inferred from the mapping. Immediately north 


1 Quart. Journ. Geol. Soc. vol. xxi (1865) p. 74. 
@23.G.S. No. 218: L 


146 PROF. T. T. GROOM ON THE GEOLOGICAL [May 1899, 


of the chief exposure of conglomerate an apparent continuation of 
the ridge, to which allusion has been made, is formed by a small block 
of Archean rock, reached by excavations. This appears to join the 
main zone of the gneissic series which runs down the northern 
slope of the western side of Raggedstone Hill, for excavations made 
to the north of the observed outcrop of the conglomerate indicate 
that the latter is absent, presumably by faulting out. In conse- 
quence of the lack of exposures along the line of contact of the 
conglomerate and this small block, Iam unable to say whether the 
case is one of superposition of the conglomerate on the gneissic 
series, or whether the junction is merely a fault. An oblique fault 
running north by west would explain the phenomena observed. 


Fig. 14.—Section in Winter Combe (north side of Raggedstone Hull). 
F 
E, 


(ab is about 52 yards in length.) 


ghia Bs Te 
x 
x 
x 
PS x 


‘ 


x & 
DEE. 


x 
x i ™ 


x x 
x 5e eKS x< X32 Seis 


Hollyhush Conglomerate 


x< 


East of the conglomerate and gneissic rocks, and forming con- 
siderable portions of the bottom and of the eastern and western 
slopes of the hollow, is a great mass of Hollybush Sandstone. 
This, it is true, is nowhere exposed in place, but its existence is 
proved by the very considerable stretches of wood covered with 
débris of nothing but the sandstone. The débris extend up toa 
height of over 700 feet on the western side of the wood, and in 
the lower part of the wood the sandstone-area covers a considerable 
breadth. The western boundary of the mass is indicated by a slight 
depression just within the wood; this probably marks a faulted 
line of junction with the conglomerate, for otherwise the conglo- 
merate would appear to overlie the sandstone, which there is every 
reason to doubt. 

This junction appears to continue the curving line of dislocation 
which traverses Raggedstone Hill, for Archzean rock oceurs not only 
in the little ridge to which reference has been made, but also in place 
on the southern side of the road, immediately opposite the entrance 
to the large quarry. It was reached, I am informed by Mr. Summers, 
in laying “the foundation of the Mission Chapel, and in excavations 

made in the gardens for some little distance to the east. It is 
probable, accordingly, that the Hollybush Sandstone extends down 


Vol. 55.] STRUCTURE OF THE SOUTHERN MALVERNS. 147 


to about the level of the road, where it must be cut out by the 
meeting of the two faults which bound it: but it does not pass 
beyond the road, for north of this Archean rocks are everywhere 
present. 

Winter Combe is, then, a hollow excavated in a shattered com- 
plex of more or less lenticular masses of Hollybush Sandstone, 
Hollybush Conglomerate, and rocks of the gneissic series. 


Fig. 15.—Section across the northern part of Raggedstone Hill. 
F F Fee as 


139 


4 

' 

t 
ee 
' 1 
' 


SS eee SS om me 


o o 
Sresaale aia 


[Seale : 43 inches = 1 mile.] 


d=Dyke in Hollybush Sandstone. 
e=Hollybush Sandstone. 
b=Hollybush Conglomerate. 

a= Archean. 


FF= Faults. 
g=Trias. 
f=May Hill Sandstone. 
e=Grey Shales (Cambrian). 


Comparing the foregoing observations, attention may be drawn 
to the fact that the included patches of Paleozoic rock all occur 
along a continuous line of depression which, starting at the south- 
eastern end of Raggedstone Hill, runs first in a north-westerly, and 
then successively in a north-north-westerly, northerly, north-north- 
easterly, and north-easterly direction, finally turning eastward. 
Its course is practically a semi-ellipse. This hollow marks a complex 
line of powerful disturbance, along which differential movements, 
to the extent of 2000 feet or more, have taken place. 


(4) The Hollybush Pass. 


This district has already been described in speaking of the 
adjacent slopes of the hills on each side, and one point alcne 
remains for consideration. 

The existence of a deep transverse depression extending right 
across the range is remarkable, but the student of the Malvern 
district soon learns that many of the faults of the area are marked 
by lines of depression at the surface. Holl, indeed, long ago! 
expressed his belief that some of the passes between the hills have 
been determined by lines of fault. It is not easy to prove the 
existence of an important fault running the whole length of the 
Pass, but there are several distinct pieces of evidence which point 
to this conclusion. 

On the west, the boundaries of the Hollybush Sandstone appear 
to be continueus across the Pass, and the general dip of the beds 
is similar in both direction and amount; but the behaviour of 


? Quart. Journ. Geol. Soc. vol. xxi (1865) p. 95. 
L 2 


148 PROF. T. T. GROOM ON THE GEOLOGICAL [May 1899, 


the intrusive masses is best explained by a fault. The two main 
dykes running down the adjacent slopes are not continuous across 
the depression, as was apparently supposed by Phillips,’ for mapping 
shows that neither passes beyond the bed of the stream. The 
very different dip and strike of the two necessitates the conclusion 
that the dykes do not even meet one another, and that in fact 
the ends of two different dykes are brought into proximity along a 
transverse line of faulting. 

The same fault would appear to form the southern boundary of 
the strip of sandstone east of that which contains the igneous rocks 
at the south-western corner of Midsummer Hill, for the dip of the 
sandstone here is different from that on the southern side of the 
stream. A continuation of the same line of faulting towards the 
west-south-west would coincide with the northern boundary of the 
patch of May Hill rocks near Fowlet Farm, to which allusion 
will be made later, and also with that of the Black Shales on the 
west of this patch. 

It is difficult to say whether the great axial line of dislocation 
has been displaced by this fault or not; but, judging by the probable 
distribution of the rocks concerned, as indicated by the relief of the 
surface, a certain amount of displacement has occurred. I could 
detect no traces of the May Hill Beds on the northern slope of 
Raggedstone Hill: the position that they might be expected to 
occupy, were there no transverse faults, would, indeed, seem to be 
taken up on the southern side of the Pass by a small mass of 
Archean rocks. 

The fault is probably one along which varied differential move- 
ments of the blocks concerned have taken place, for no simple 
movement would appear to be capable of bringing about the 
observed relations of the rock-masses. 


(5) The Gullet Pass. 


The Gullet, or line of depression between Midsummer and Swin- 
yard Hiils, as already pointed out (p. 140), is a line of dislocation. 
Against this fault end the four faults bounding the Archean blocks 
on the north and south. It isin part, at any rate, of post-Triassic 
age, for it has dislocated the great fault by which the Triassic 
rocks have been thrown down on the eastern side of the range (see 
map, Pl. XIII). 


(6) Chase End Hill. (Fig. 16.) 


The structure of this southernmost portion of the Malvern range 
is simpler than that of the hills already considéred. The hill is 
somewhat lanceolate in plan, and its axis meets that of the southern 
part of Raggedstone Hill at about a right-angle. 

The greater part of Chase End Hill is formed by an elongated 
elliptical mass of schistose and gneissic rocks. Near the north- 


1 Mem. Geol. Surv. vol. ii (1848) pt. i, p. 53. 


Vols. | STRUCTURE OF THE SOUTHERN MALVERNS. 149 


eastern end of this mass the hill sends a spur towards the north- 
west. This is represented in the Survey maps as a continuation 
of the gneissic series, but in Holl’s map* it is correctly marked as 
part of the Malvern Shale Series. 

A smaller, more northerly spur runs north-westward from the 
extreme northern end of the hill. This is formed by a slip of 
Hollybush Sandstone, together with Black Shale and basalt. The 
structure of these spurs may be conveniently considered together 
with that of the district of White-leaved Oak (p. 159). 

The schistose and gneissic rocks of the hill appear to be bounded 
everywhere by faults: on the south-east and east, by the great 
fault which brings down the Trias; on the north-west, by a fault 
which intersects the surface in a curved line, against which strike 
the successive zones of the Malvern Shales. 


Fig. 16.—Section across Chase End Hill, on the scale of 
6 inches to the mile, 


' 
eG A 


c 


} 


[The above figure represents the probable relations of the rocks of the hill ; 
the section is not drawn parallel to the dip of the shales, nor to that of 
the fault, and thus both dips appear to be lower than they really are. | 


F'F'=Fault between Trias and b=Grey Shales, with interbedded 
Archean. diabase (Coal Hill igneous 
FF= Fault. band). 
d=Trias. a= Archean. 


c= Upper Grey Shales. 


The Triassic rocks are exposed along the drive to Bromsberrow 
Place, in the form of a red sandstone with occasional pebbles of 
pink quartz. The dip is south-westerly at about 20°. 

The fault running along the north-western slope of the hill 
curves round on the north-east towards the east, and on the south- 
west towards the south-east, as it descends to lower ground in 
each case. The actual junction is nowhere exposed, but a plane 
fault dipping south-eastward at an angle of 30° would give an 
outcrop closely agreeing with that observed (fig. 16). 

The Upper Grey Shales, wherever seen close to the ridge, have a 
reversed dip towards the east-north-east, while the lower strata 
of the same series, with interbanded basalts, seen in the spur 
farther north-eastward, dip east by north. 


1 Quart. Journ. Geol. Soc. vol. xxi (1865) facing p. 72. 


150 PROF. T. T. GROOM ON THE GEOLOGICAL [May 1899, 


(7) Confirmatory Evidence from the more Northerly 
Portions of the Range. (Fig. 17.) 


The boundaries of the Archean complex in the central and 
northern portions of the range have been carefully mapped, and the 
conclusion has been reached that, as in the south, the western 
boundary is always a fault, sometimes vertical, and sometimes 
reversed. A deseription of these portions of the range is reserved 
for a future communication, but in view of the scarcity of exposures 
of the junction with the Paleozoic Series in the south, I have 
thought 1t well to give an example from the middle portion of the 
range, which proves that, on the one hand, the Archean Series has 
been intensely folded, and that, on the other, it has undergone 
powerful overthrust on to the Silurian rocks. 


Fig. 17.—Section of the range along the line of the Malvern Tunnel. 


FY Ps 
Av SS , 
\ 3 7 mae Oa Fy 
S.66 E ee 1 as 
REN vat cena x 
A tate A 
r e d c \a DN a ce 


[Seale: 43 inches=1 mile. ] 


e = Wenlock Shale. 
d = Woolhope Limestone. 


rr = Railway-level. 
F'F'=Fault between Trias 


and Archean. ¢ = Tarannon Shales. 
FF= Faults. | 6 = May Hill Sandstone. 
g = Breccia. a = Archean. 
f= Tnas: | 


The above figure represents a section drawn to scale across the 
range, along the line of the Malvern Tunnel. The succession 
of strata in the tunnel is taken from Symonds & Lambert’s 
description,’ in which measurements are given. The junction 
of the Archean with the May Hill and Triassic strata on the slope 
of the hill has been fixed by careful mapping. 

It is clear from this section that the fault separating the Archean 
rocks from the May Hill Series has a very considerable hade 
towards the eastern side of the hill. The angle of apparent dip 
indicated by the line joining the point of outcrop at the surface 
with that of intersection by the railway is about 57°. Making 
allowance for the angle at which the railway cuts the dip of the 
plane of junction, as deduced from its outcrop, I estimate the true 
dip as being about 65° east, 7° south. That the junction really dips 
eastward was noted by Symonds & Lambert,’ who state that the 


1 Quart. Journ. Geol. Soc. vol. xvii (1861) p. 152. 2 Ibid. pp. 155, 157. 


Vol. 55.] STRUCTURE OF THE SOUTHERN MALVERNS. 151 


vertical Llandovery Beds, which show indications of great pressure 
and crushing, rest against the overhanging ‘ syenite.’ 

An important feature in this section is the occurrence of a‘ vein’ 
of Llandovery rock included in the ‘ syenite,’ and consisting of two 
thin bands of limestone (each ?) about 6 inches thick, with an 
intervening bed of‘ marl,’ 2 feet thick. These beds, according to 
Symonds, furnished Stricklandinia.’ It is unfortunately very diffi- 
cult to make out the disposition of this ‘vein’ from Symonds & 
Lambert's description,” but on comparing the figure and the context 
it seems to follow that it has a low easterly dip. 

The same or another strip of beds containing Stricklandinia was 
also described by Phillips * as occurring in the crystalline rock of 
the Wyche Pass, a short distance north of the line of the tunnel. 

Symonds explains these facts by supposing that the fossiliferous 
rocks were dropped into an open fissure traversing the crystalline 
floor of the Llandovery seas ; but, now that the great effects accom- 
panying the process of mountain-building are known, no one will, 
I think, seriously maintain this view, and I would apply the same 
explanation here as in the case of the included Cambrian and 
Silurian strips in the southern part of the Malvern chain, namely, 
that of profound infolding, combined with faulting. 


(8) Theoretical Explanation of the Structure of the 
Southern Portion of the Malvern Range. (Figs. 18-20.) 


The broken and dislocated condition of the gneissic complex of 
the Malvern Hills was realized many years ago by Phillips, who 
in this connexion drew special attention to the occurrence of 
crush-breccias. These breccias have been noted subsequently by 
Holl, Rutley, and Hughes, the latter of whom has given an ex- 
planation of their origin* The two former have also indicated 
the occurrence of faults traversing the gneissic series. Now, the 
faults occurring in the range are by no means always of the simple 
character of those to which allusion has just been made. It has 
been shown above (p. 137) that Midsummer and Raggedstone Hills 
are traversed by a complex line of dislocation, along which strips of 
Cambrian and Silurian rocks, presumably often of lenticular shape, 
have become included in the Archean Series. The inclusion of 
these narrow strips is difficult, and I think impossible, to explain on 
the- hypothesis that they are portions of an overlying series let into 
the gneissic series by ordinary faulting. At the only spot (fig. 11, 
p- 143) where the actual junction of the included rocks with the 
Archean Series is exposed, the fault is seen to be a reversed one, 
but with a relatively smali hade. The circumstance, moreover, 
that the outcrop of the line of disturbance curves round towards 
the east, as it descends both the northern and southern slopes of 


? «Old Stones’ 2nd ed. (1884) p. 47. 

2 Quart. Journ. Geol. Soe. vol. xvii (1861) p. 157. 
3 Mem. Geol. Surv. vol. ii (1848) pt. i, p. 64. 

* Geol. Mag. 1887, p. 500. 


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Vol. 55.] GEOLOGICAL STRUCTURE OF THE SOUTHERN MALVERNS. 153 


Raggedstone Hill, suggests that it has on the whole a distinct 
easterly dip, and therefore passes underneath the gneissic rocks of 
the eastern side of the hill. Further, it wil! be shown on a future 
occasion that, in the more northerly portion of the range, the 
eastern fault bounding similar included Silurian strips is either 
vertical, or has a very marked hade towards the east. 

There is, then, evidence to show that the gneissic rocks on the 
eastern side have been thrust up vertically, or at an angle, over 
the more westerly Cambrian and Silurian rocks. This hypothesis 
necessitates, further, the presence of folds sufficiently deep to bring 
the Palzozoic strata down to the level at which they are found. 
I have endeavoured to represent this view in the entirely diagram- 
matic figure facing this page. We must suppose that a deep fold 
of Cambrian and Silurian rocks, including on the one hand the 
Hollybush Conglomerate, and on the other beds of the May Hill 
Series, became included in the gneissic complex, the middle limbs 
being drawn out by the great tension into a series of shreds, or in 
places entirely obliterated. 

A fact worthy of note in this connexion is that, though the 
Hollybush Conglomerate and Sandstone, and the May Hill Sand- 
stone are represented in this squeezed and dislocated zone, the 
Malvern Shales, the position of which is intermediate between the 
two last-mentioned formations, appear to be entirely unrepresented. 
There is, as I shall endeavour to show later, reason to believe that 
these beds, like the other Cambrian and the Silurian strata, formerly 
passed over the range, and I would suggest that during the intense 
folding and crushing which took place these softer beds were 
completely squeezed out, in the manner indicated in fig. 18. The 
enormous crushing which some of the beds have undergone is shown 
by the greatly shattered and brecciated condition of the pieces 
of Hollybush Conglomerate found in the hollows at the southern 
ends of Midsummer and Raggedstone Hills respectively. Very 
significant In connexion with these folds and thrust-planes are 
the definite relations which obtain, between the strike and dip of 
the schists of Raggedstone Hill and the course of the axial dislo- 
cation as shown in the map (Pl. XIII). The schists nearly every- 
where on the eastern side of the hill dip away from the line, their 
strike curving round with a fair amount of regularity; the 
schistose rocks on the western side of the hill show a similar but 
less marked relation, the folia dipping towards the axial line in 
this case. It can hardly be doubted that the production of the 
schistosity and that of the zone of dislocation are closely related. 

Further evidence tending in the same direction is seen in the 
western slopes of Raggedstone Hill. It has already been pointed 
out (p. 137) that there is commonly a distinct relation between 
the dip and strike of the Cambrian rocks and of the schists, on 
the one hand, and that of the fault-plane separating them on the 


? I do not, however, feel perfectly satisfied with this explanation, for some 
traces of the igneous rocks abundant in parts of the shale series might be 
expected to occur. Future research may remove this difficulty. 


154 PROF, T. T. GROOM ON THE GEOLOGICAL [May 1899, 


other. The schists commonly dip towards the axis of the hill, as 
also do the inverted Black Shales, and sometimes the Hollybush 
Sandstone. The schists in the large quarry at White-leaved Oak 
show clearly a series of small folds overthrown to the west, and 
it may be seen that they are traversed by a small reversed fault. 
Taking into consideration this disposition of the schists, together 
with the inversion of the Black Shales, I would suggest that evidence 
here exists of an overfold towards the west, the Archzan strata 
having been thrust over the Cambrian Series, with the result that 


Fig. 19.—Diagrammatic view of the structure of Midsummer Hill. 


‘ 
‘ 


XN 
‘ 
‘ 


Wires fy. 
Ts YU 
ine CY 
Yy, Wy boa My Y , i 


= 


—~ 


\' 
\ 


SS 


Y) 


LZ 


ASS 
NSES 
Sack : 
By 

Ss 


SoS 
< 


SS 
AN 


SS 
SS 


Ui lg 


yy Hee 
YY 


VK 
MM) 
Meg pay Vy Ly YG, 
F 


Uy 
il AON, a.’ Z Uy 
i 2 “ge iy 


M ES, 
a 1 
; Bur F 
FF=Faults. d= Black and Grey Shales (Cambrian). 
F' F'=:Fault between Trias and c= Hollybush Sandstone. 
Archzan. b=Hollybush Quartzite and Con- 
g=Trias. glomerate. 
f=Haffield Breccia, a= Archean. 
e=May Hill Beds. xx = Present surface. 


new planes of schistosity were introduced in the former. The fold 
was finally ruptured by a fault, which probably was nearly vertical. 

The disposition and relations of the Hollybush Sandstone, how- 
ever, need further elucidation. This, as already shown, is probably 
thrown into a small overfold, the axis of which dips towards the 
west, as also does in some cases the fault-plane between it and the 
schists. Figs. 4, 5, 6, & 7 (p. 136) illustrate this arrangement, I 


Vol. 55.] STRUCTURE OF THE SOUTHERN MALVERNS. 155 


would suggest that originally the schists and sandstone and the 
fault separating them dipped eastward, but that movements, a 
little later than those which produced this thrust, resulted in the 
formation of a small overfold towards the east. 


The structure of Midsummer Hill and of the north-western 
corner of Raggedstone Hill presents points of difference from that 
seen in the greater part of the last-named hill. There is an 
axial thrust-plane, the gneissic and schistose beds above which, 
at the southern end of Hollybush Hill, dip eastward. Débris of 
fossiliferous May Hill Sandstone found in the trench at the extreme 
northern end of the camp, at a height of about 750 feet, may 
possibly indicate another thrust-plane: but the foliation of the 
schists and gneisses in general does not appear to show any relation 
to the axial thrust-plane, nor to the boundaries of the gneissic 
complex. The hill, indeed, shows in a marked way the structure 
termed plagioclinal by Dr. Callaway. The dip of the Cambrian 
beds, moreover, is prevailingly towards the west, no signs of 
inversion being seen, except in the case of the conglomerate near 
the northern end of Midsummer Hill (M 366). 

The structure may be explained in much the same way as that 
of the greater part of Raggedstone Hill, if we suppose the move- 
ment not to have been generally great enough on the one hand to 
produce overfolding on the western side, or, on the other, to induce 
new planes of foliation on a large scale (see fig. 19). Secondary 
foliation appears, however, to have taken place at the southern 
end of Hollybush Hill above the axial thrust-plane. 

The plagioclinal structure seen in Midsummer Hill and in many 
other parts of the Malvern range is perhaps best explained by the 
hypotheses of Dr. Callaway,’ who suggests that the Cambrian 
beds rest unconformably upon the Archean. ‘The latter series had 
in pre-Cambrian times undergone an extensive process of folding 
before being denuded, the axes of the folds crossing the direction 
of the range obliquely. 

Little need be said about the structure of Chase End Hill. If 
the explanation given on p. 149 be true, this hill constitutes a case 
of extensive overthrust, the overridden shales being inverted by 
the movement, and a new foliation having been probably developed 
in the Archean rocks. That such extensive overthrust has occurred 
in parts of the Malvern range the evidence given on p. 150 is 
sufficient to show: there,is proof of intense folding, accompanied 
by the formation of thrust-planes. Fig. 20 (p. 156) is an attempt to 
explain the structure of the western part of the range at the point 
at which the section in fig. 17 (p. 150) is drawn. 

To summarize, I would suzgest that the Southern Malverns are 
a portion of an intensely folded and faulted complex of Archean, 
Cambrian, and Silurian rocks, showing the characteristic features 
of a folded mountain-range, with its overfolds and thrust-planes. 


1 Geol. Mag. 1879, pp. 219-221. 


156 PROF, T. T. GROOM ON THE GEOLOGICAL [May 1899, 


One interesting point of resemblance to certain typical mountain- 
ranges is the occurrence of transverse faults, such as that which 
runs down the Gullet Pass, between Midsummer and Swinyard 
Hills. It follows, moreover, from Phillips’s description of the 
Silurian rocks west of the Malverns,’ that the strata are thrown 
into a series of normal folds, which run in a direction generally 
parallel to that of the Malverns themselves ; the anticlines of this 
system have a steep westerly, and a more gentle easterly dip, so 
that the axes dip east- 
ward. This series of folds 


(fig. 18, p. 152)is a good Fig. 20.—Theoretical restoration of the 


section of the Malvern Hills along the 


example of the Austo- line of the Malvern Tunnel (p. 150). 
nungszone commonly 

assoclated with moun- 

tain-ranges. A further b 

apparent resemblance to Fy 

such ranges consists in Fo ie 

the depressed block of \ iy aw. 

country east of the Mal- ‘ Nh | ihiarinananiae 

verns: this, at first sight, \ 

may be held to constitute \ 


the Abgesunkenes 
Riuckland of Conti- 
nental geologists ; but it 
must be noted that the 
movement which took 
place along the line of 
fault between the Mal- 
vern range and the Trias 
of the Vale of Gloucester 
is, In part at any rate, 
necessarily of post-Tri- 
assic age, and hence 
long subsequent to the 
movements which pro- 
duced the old Malvern 
range. “YU Yy 
Beneath the ‘ Permian’ 
and Triassic rocks east of 


the hills, there is every inp Yj 
MMM 


Yj Vy 

Yyy 

/ ; BA Uy 
reason to believe that Y YY / We pty, 


relics of the easterly ex- ‘, a * 


tension of the old range 


survive. Suchformations zr=Present surface. | b=Lower Paleozoic. 
have long been known to FF=Faults. a= Archean. 

rest. directly upon the 

older series in the Malvern and Abberley districts. The fault on 
the eastern side of the Malvern range has depressed the Archean 


* Mem. Geol. Surv. vol. ii (1848) pt. i, p. 134. 


Vakig5-] STRUCTURE OF THE SOUTHERN MALYERNS. 157 


and Lower Paleozoic mass with its covering of ‘ Permian ’ and Trias, 
while denudation has largely removed this covering on the western 
side of the fault. 

The Southern Malverns may, then, be regarded as a portion of 
the front of an old mountain-range, more or less of the Jura-type, 
the folds of which have been overthrown and overthrust westward. 
I have already maintained ' that this range first arose during late 
Carboniferous times, and I hope to submit detailed evidence in 
support of this hypothesis on a future occasion. 

It finally follows that, if the views set forth in the foregoing 
pages be correct, we shall have to recognize in the crystalline rocks 
of the Malverns, not only an unmodified pre-Cambrian series of 
gneisses and schists, but also a newer series of schists formed 
from the old material, and comparable in their secondary origin 
with those produced in Northern Scotland by the post-Cambrian 
movements. 


IV. Tae Wesrern Tract. 


The tract bounded on the east by Midsummer, Raggedstone, 
and Chase End Hills, and on the west by the May Hill Sandstone 
escarpment, falls naturally into three districts, which show certain 
physiographical and geological differences :— 


(1) The district of White-leaved Oak, Pendock’s Grove, and Coal 
Hill, which extends southward as far as Hayes Copse, at 
the south-western end of Chase End Hill. 

(2) The district between Pendock’s Grove and the gentle ridge on 
which Fowlet Farm and Martins are situated. 

(3) The district around Bronsil. 


(1) The District of White-leaved Oak, Pendock’s Grove, 
and Coal Hill. 


It is in this area that the geological structure is best shown. 
The strata have undergone comparatively little displacement, and 
exhibit a generally simple arrangement, well revealed in several 
picturesque glens which diversify the district. 

The only strata present in this district are the Malvern Black and 
Grey Shales, with which are associated series of igneous rocks, and a 
small patch of May Hill Sandstone. The Cambrian shales were 
termed ‘ Black Shales’ by Phillips,’ but Holl*® afterwards divided 
them into a lower series of Black Shales and an upper series of 
Grey Shales. Careful mapping shows that the Grey Shales occupy 
a much larger area than would be inferred from the current 
descriptions.* 


1 Rep. Brit. Assoc. 1898 (Bristol) p. 873. 

* Mem. Geol. Surv. vol. ii (1848) pt. i, p. 54. 

3 Quart. Journ. Geol. Soc. vol. xxi (1865) pp. 89 eé segg. 

* Holl, op. cit. p. 92; Symonds, ‘ Records of the Rocks,’ 1872, p. 72, & 
‘Old Stones,’ 2nd ed. (1884) p. 31. 


158 PROF, T. T. GROOM ON THE GEOLOGICAL [May 1899, 


In the locality now under consideration the Black and Grey 
Shales together form part of a fold the axis of which is directed 
north-westward, and the north-eastern limit of which is overthrown 
and faulted against the Hollybush Sandstone and Archean (figs. 4-6 
& 13, pp. 136, 144), while on the south-east the series is overridden 
by the schists of Chase End Hill, and, at any rate in the southern 
part of the district, inverted (fig. 16, p. 149). 

The best section in the district is that taken from the village 
of White-leaved Oak, south-westward down a little valley running 
between Pendock’s Grove and Coal Hill (fig. 13, p. 144). 

The Hollybush Sandstone at White-leaved Oak forms a steep slope 
on which many cottages of the village are situated (Pl. XIV): the 
beds dip west-south-westward at a high angle. At the foot of the 
slope the Black Shales are seen, often much disturbed and generally 
inverted, so as to dip at an angle of 60° or more in a north- 
easterly direction. The mutual dip of the sandstone and shales 
towards one another can be explained only on the supposition that 
the junction is a fault. 

A well-marked band of basalts interstratified with shales passes 
through the village, forming a round-backed ridge, the central line 
of which crosses the road immediately south-west of the village. 
This band is tripartite, there being three minor bands chiefly com- 
posed of basalts, separated by two thinner bands made up essentially 
of Black Shales. 

The Black Shales on the north-eastern side of this igneous band 
have an inverted north-easterly dip, as seen in the fields north 
of the village. Those interstratified with the basalts are almost 
vertical, and those overlying the igneous band have a very high 
south-westerly dip. Traced south-westward, the Black Shales are 
last seen at the northern corner of Pendock’s Grove. Beyond this 
point the Grey Shales commence, and at their base are interstratified 
with basalt. This band, accordingly, forms a second well-marked 
ridge, separated from the first by a considerable depression occupied 
by black Shales with little or no igneous material. | 

Igneous materials seem to occur almost everywhere in the Grey 
Shales along the rest of the line of section, but are specially developed 
only along a third ridge, passing through the middle of Pendock 
Grove, and forming Coal Hill on the other side of the glen. Basalts 
occur in the lower part of this band, but the chief igneous rocks 
are ophitic diabases ; these are well-exposed in the garden of-the 
cottage at the north-western end of Coal Hill. The interstratified 
shales and diabases here dip south-westward at an angle of 35°. 

Between the western foot of the Coal Hill ridge and the May Hill- 
Sandstone escarpment the Grey Shales can be traced along the 
line of section by abundant débris only, and the determination of 
the exact position of the junction of the shales with the Llandovery 
Beds was a matter of difficulty, but was effected, I think, with 
some approach to accuracy by the aid of excavations, and by noting 
the upper level to which the shale-débris extended. 

In the extreme eastern corner of the district traces of another 


Vol. 55.] STRUCTURE OF THE SOUTHERN MALVERNS. 159 


igneous band may be recognized forming, together with a strip of 
Hollybush Sandstone and the lowest Black Shales seen, the small 
spur running north-westward from the north-eastern extremity of 
Chase End Hill (see p. 149). 


It will be seen from the foregoing description that, between the 
Malvern range and the May Hill Sandstone escarpment, there is a 
great shale series, in which bands of igneous rock are intercalated 
at several horizons; and that, while near the Malvern range the 
beds are inverted so as to dip at angles of 60° or less into the hills, 
a short distance away they become vertical, and then dip at a high 
angle in the opposite direction, and that still farther from the axis 
they assume a somewhat low normal dip. The shales accordingly 
form part of a fold, the north-eastern limb of which is overthrown. 

We may, from an examination of the district, distinguish the 
following horizons in the Malvern Shales :— 


Upper Grey Shales. 


Coal Hill igneous band. 
Grey SHALES ....... S Grey Shales. 


Middle igneous band. 
Upper Black Shales. 
ee eatiik Upper White-leaved Oak igneous band. 
tee Lower Black Shales. 
Lower White-leaved Oak igneous band. 


Of these eight bands the upper seven can be traced more or less 
clearly over the whole of the sub-district, the three chief igneous 
bands forming well-marked ridges, which run uniformly from south- 
east to north-west, and the intervening shales forming equally well- 
defined but small strike-valleys. The course of the two upper 
igneous bands is interrupted, first by the valley along which the 
section in fig. 13 (p. 144) is drawn, and secondly by a less marked 
depression which, running about north and south, separates Coal 
Hill from the north-western slopes of Chase End Hill. 

The upper White-leaved Oak band (Pl. XIV) forms the highest 
and most continuous of these ridges. It extends from the northern 
corner of Pendock’s Grove for a distance of 4 mile south-eastward, 
where it abuts against the schists of Chase End Hill, forming the 
northern part of the main spur of this hill. The surface formed by 
the Lower Black Shales slopes down somewhat steeply on the flank 
of Raggedstone Hill, but south-east of White-leaved Oak a deep 
hollow—the Valley of White-leaved Oak—is excavated largely in 
these shales. 

The Upper Black Shales west of White-leaved Oak form a rather 
deep depression along the eastern border of Pendock’s Grove, while 
south of the village a slight depression only is observable. 

The middle igneous band forms a pronounced ridge extending 
along the northern portion of Pendock’s Grove, and, after a partial 
interruption by the main transverse glen, continues its course to a 
point immediately beneath the summit of Chase End Hill, the main 
spur of which it largely forms. 


160 PROF. T. T, GROOM ON THE GEOLOGICAL [May 1899, 


The Coal Hill igneous band forms a sharp ridge extending right 
across Pendock’s Grove, a second shorter ridge known as Coal Hill, 
and an ill-marked tract of hummocky ground, constituting part of 
the north-western slope of Chase End Hill. 

At Coal Hill Cottage, as already stated, the dip is 35° to the 
south-west. At the south-eastern end of Coal Hill the beds are 
vertical, and at the foot of Chase End Hill the uppermost beds of 
the series are inverted, so as to dip east-north-eastward at 45°. In 
the south-western part of the band, accordingly, the inversion of 
the beds may be traced as they approach the schists of Chase End 
Hill. 

The Upper Grey Shales form a broad band of greater Jength than 
the three last-mentioned zones. This extends from thenorth-western 
margin of Pendock’s Grove to Hayes Copse on the south, a distance 
of about 3 mile. The surface of the median portion of the band is 
depressed, and the ground rises on the one hand towards the Coal Hill 
band, and on the other towards the May Hill Sandstone escarpment 
(fig. 13, p. 149). The only actual exposure of the shales is seen 
in the southern part of the district, near Hayes Copse, where the 
inverted beds dip east-north-eastward at 27°: no igneous rocks 
occur here. A solitary semicircular boss of basalt constitutes the 
only prominent igneous mass seen in the Upper Grey Shales of 
this sub-district. 

The northern corner of Pendock’s Grove is occupied by a 
quadrangular block of May Hili Sandstone (M 355) and Grit 
(coarse sandstcne), bounded on all sides by faults, which are more 
or less clearly defined by depressions of the surface. On its eastern 
side the sandstone is faulted against both Black and Grey Shales, 
several of the zones of which strike up against it (see fig. 21). The 


Fig. 21.—Section of Cambrian and Silurian rocks, between White- 
leaved Oak and Fowlet Farm. 


[Scale: 6 inches=1 mile. ] 


FF= Faults. a= Black Shales and basalts 
b=May Hill Sandstone. (Cambrian). 


rocks are exposed only at the extreme north-western corner of the 
patch. The fossils found among the débris include Lindsiremia 
subduplicata, Tentaculites, Orthis, and crinoids. A small patch of 
Black Shales, with associated igneous rocks (M 223), occurs on the 
southern boundary of the block. 


— 


Wolk 55-1] STRUCTURE OF THE SOUTHERN MALVERNS, 161 


(2) The District between Pendock’s Grove, Martins, and 
Fowlet Farm. 


The district lying between Pendock’s Grove and the gentle ridge 
extending from Rowick to the north-western corner of Raggedstone 
Hill is of complex structure, and at the same time of very imperfect 
exposure. It is almost exclusively covered with undulating pastures 
and arable land, in which practically the only rock-exposures are 
those seen on the top of certain tumps and small ridges formed by 
basalts and diabases intrusive in the Malvern Shales. These, witha 
number of small excavations made by the writer, and a few actual 
exposures of Malvern Shale, Llandovery rock, and Drift, together 
with the distribution of the débris of various kinds scattered over 
the surface, show that the district is a faulted complex of Black 
Shales, Grey Shales, May Hill Sandstone, and igneous rocks, covered 
in places by a stratified Drift. 

In the south-western part of the area the Upper Grey Shales 
are continued north-westward. Igneous rocks associated with them 
are seen in two small but conspicuous bosses (M101 & 101a) 
near the farm known as Martins, and a smaller one (M 102) near 
Pendock’s Grove. ‘This latter is shown by excavations to be con- 
nected with the small hill (M 101a) along a gentle ridge running 
north-west and south-east: that is, in a direction agreeing with the 
strike of the beds in the Pendock’s Grove district. 

The Coal Hill igneous band also appears to be continued for some 
distance into this district. An old quarry (M103) is situated on 
one of the chief diabase-sills of this zone. 

The northern corner of the district is occupied by a patch of May 
Hill Sandstone and Grit, no exposures of which occur, but the 
presence of which is shown by excavations and by abundant débris. 
The patch is apparently bounded on all sides by faults, which 
separate the sandstone on the north-west from the Grey Shales, and 
from another block of May Hill Sandstone; on the north-east, from 
the Hollybush Sandstone; on the east and south, from the Black 
Shales and associated igneous rocks. 

The Black Shales and igneous rocks on the eastern side of the 
block are apparently a continuation of the upper White-leaved Oak 
igneous band and Lower Black Shales. The igneous rock is exposed 
only at one point (M 157a), and the Black Shales are not exposed 
at all north of the road from Fowlet Farm to White-ieaved Oak, 
but their presence was indicated by some débris at one spot north 
of this road, and more, together with basalt, was reached in an 
excavation made near the hedge north-east of M 157a. Basalt 
(M 175)* was reached, in excavations made for drain-pipes, in 
the northern angle between the sandstone-patches of Pendock’s 
Grove and Fowlet Farm ; but it is uncertain whether this basalt is 
in place. 

The May Hill Sandstone patch east of Fowlet Farm includes 
yellowish micaceous sandstone (M 153), purple grit (M 150), and 


1 [Omitted from the map, Pl. XIII. ] 
Q7d.G.5. No. 218. M 


162 PROF. T. T. GROOM ON THE GEOLOGICAL [May 1899, 


blue loam (M 151),! evidently resulting from the decomposition of 
fine argillaceous sandstone. ‘The best section seen of the May Hill 
Beds was exposed in making a cistern (M 151 & 152) near the 
Fowlet Farm cowshed. In this 2 feet of reddish-yellow soil passed 
down into 3 feet of blue clay, the upper part of which contained 
derived fragments of Hollybush Sandstone; the lower fragments were 
of argillaceous sandstone only, showing all stages of decomposition 
into blue clay: below this, a thickness of 3 teet of disintegrated 
purple sandstone was seen. The junction of the clay and purple 
sandstone was an undulatory surface dipping mainly northward, but. 
sometimes north-eastward, at an angle of 10° or less. Both beds 
furnished fossils ; among these I recognized the following :— 


Lindstremia subduplicata, M‘Coy. Atrypa reticularis, Linn. 

L. s, var. crenulata. Pentamerus sp. 

Favosites asper (2) d’Orb. Stricklandinia lens (?) Sow. 
Leptocelia hemispherica, Sow. Pterinea sp. 

Strophomena antiquata, Sow. Gasteropods. 

Orthis calligramma, Dalm. Tentaculites anglicus, Salt. 
Orthis sp. Orthoceras sp. 

Spirifera elevata, Dalm. Enerinurus punctatus, Brann. 
Spirifera crispa, His. Crinoids. 


The existence of Llandovery rocks in the neighbourhood of Fowlet 
Farm was known to Phillips, Holl, and Symonds. Phillips? said: 
‘There are beds of true Caradoc sandstone (No. 6), with fossils in 
tolerable plenty, near Fowlet Farm, thrown down by some obscure 
but powerful displacement, or deposited unconformably.’ Holl? and 
Symonds * regarded the patches here, and to the north, as outliers 
resting unconformably upon the Cambrian rocks. 

That these patches are in reality blocks faulted into the Cambrian 
is evident, first, because not only do the basaltic ridges and inter- 
stratified shales strike directly towards the sandstone in such a 
way that it cannot be supposed that the latter overlies the shales 
(fig. 21, p. 160), but the sandstone itself appears to strike up against 
the shales ; secondly, the rectilinear boundaries point towards the 
same conclusion; and finally, to all appearance, the Llandovery Beds 
in the escarpment to the west dip in approximately the same 
direction, and probably at nearly the same angle, as the underlying 
Grey Shales (see p. 167), wherefore the basal beds of the escarpment 
would pass far above the sandstone of the patches (fig. 13, p. 144). 

The geological structure of that part of the district which lies 
between the igneous bands of the Grey Shales and the May Hill- 
Sandstone patches of Fowlet Farm and Pendock’s Grove is by no 
means clear. The chief exposures consist of igneous rock. A well- 
marked circular boss of basalt (M 104) occupies the angle between 
the two patches of sandstone, and a smaller boss (M 124 & 125) is 
seen west-north-west of this, In the road, 30 yards south-south-east 


* [Marked 157 on the map, Pl. XIII. ] 

* Mem. Geol. Surv. vol. ii (1848) pt. i, p. 54. 

* Quart. Journ. Geol. Soe. vol. xxi (1865) p. 94. 
* Proc. Geol. Assoc, vol. iii (1873) p. 269. 


Vol. 55.| STRUCTURE OF THE SOUTHERN MALVERNS. 163 


of the cottage immediately west of Fowlet Farm, a porphyritic 
basalt (M 356) is exposed in the hedge-bank; and Fowlet Farm 
itself is situated on similar basalt (M 451). A considerable hump of 
an oval shape (M 224 & 198) is situated south of M104. The 
rock itself is not exposed here, but the débris abounding on the 
surface of the ploughed field which covers it indicate the presence 
of much basalt. 

Diabase (M 447)? is exposed on the road between Fowlet Farm 
and the cowshed south-east of this, and the cottage immediately west 
of Fowlet Farm is situated on another patch of diabase (M 372), well 


shown 1n the road. 


The shales with which these igneous rocks are associated are very 
imperfectly exposed; the area north of the igneous bosses near 
Martins is covered by a thick deposit of Drift, and excavation in the 
lower ground failed to reach the rock. 

Much indurated shale of a ight colour, such as is found in con- 
nexion with the igneous rocks in both the Black and Grey Shales, 
occurs with the basalt of M 224 & 198, but no unaltered Black 
or Grey Shale was seen here in sufficient abundance to enable me to 
determine whether the basalts belong to the Black or to the Grey 
Shales. In a little hollow, however, immediately west of M 224, 
generally occupied by a pool, Black Shales are seen dipping west by 
south at 30°. These appear to be faulted against the Coal Hill 
igneous band, which is seen immediately to the westward. This 
suggests that the basalts on the north-east are also in Black Shale. 

Black Shale occurs associated with the basalt at M356. 

A well sunk many years ago, toa depth of 84 feet in the orchard of 
the cottage west of Fowlet Farm, and immediately south of the dia- 
base M 372, showed, as I am informed by the cottager, nothing but 
Black Shale and ‘yellow stuff’ (perhaps weathered basalt or diabase); 
and in a trench cut across the orchard a short time ago I observed 
a great quantity of disturbed Black-Shale débris, almost certainly 
thrown out from this well. An excavation (M 194) made many 
years ago south-west of the well, apparently in search of coal, shows 
abundant débris of Black Shale, and similar fragments seen in the 
hedgerow seem to connect this patch with that of the well. 

These occurrences indicate the existence of one or more faulted 
blocks of Black Shale in the district. Possibly, all the igneous masses 
enumerated above belong to two or three such patches, and as such 
I have provisionally mapped them, though it must be clearly under- 
stood that this point is by no means certain. 

The northern slope of the ridge between Fowlet Farm and Martins 
is largely formed by the Grey Shales. These are exposed in the 
main road north of Fowlet Farm, where the beds dip irregularly in 
a northerly direction at a low angle. West of this point, and 
directly along the line of strike of the Coal Hill igneous band, is a 
quarry in a mass of diabase (M 106) crossing the road. Debris of 
the same rock associated with indurated shale may be traced up the 


1 [Omitted from the map, Pl. XIIT.] 
m2 


164 PROF, T. T. GROOM ON THE GEOLOGICAL [May 1899, 


slope to the south-east. On the top of the ridge, immediately 
south of the road between Fowlet Farm and Martins, an excavation 
revealed Grey Shales dipping south-westward at alow angle. The: 
diabase and indurated shale-débris seen in the neighbourhood 
doubtless represent the north-western continuation of the Coal Hill 
band. 


The excavation at M 194 which furnished Black Shales contains 
a remarkable breccia, of which many fragments may be collected 
from beneath the turf, but neither shales nor breccia can be now 
seen in place. A very similar breccia with red sandstone (M 176) 
was reached in making a trench for pipes to the cistern (M 151, 
152), and may also be seen in place close to the hedgerow near the 
cowshed. The breccia is made up of alternating layers of fine 
and coarse material: the dip of these layers is difficult to deter- 
mine, as very little of the rock is exposed, but I suspect that the: 
beds are approximately horizontal. Immediately north of this 
breccia were turned out the blocks of basalt (M 175) to which 
reference has already been made (p. 161). 

The breccia is quite different from anything else that I have seen 
in the Malvern district, and I have so far been unable to determine 
with certainty whether it is a sedimentary rock at all. It consists 
chiefly of angular fragments of rocks, all of which can be matched 
in the neighbourhood ; many of the fragments are subangular, and 
a few well-rounded. The sandy matrix is thoroughly impregnated 
with an abundant cement of limonite. This rock will be more 
fully considered in a future communication, containing an account 
of the lithology of the Malvern range. At present, I see no reason 
for placing it among the Palzozoic rocks of the district. 

A description of the horizontal beds of Drift which cover most 
of the low ridge between Fowlet Farm and Martins is likewise 
deferred. 


(3) The District around Bronsil. 


The Bronsil district appears to be composed exclusively of 
Cambrian Grey Shales, with the associated igneous rocks, May Hill 
Sandstone, and Drift; but most of the area forms pasture-land, with 
very few rock-exposures. 

The Grey Shales occupy the greater part of the district, as shown 
by exposures, excavations, and shale-débris. Points at which there 
is a reasonable certainty that the Grey Shales occur are indicated 
by a symbol (x) in the map (Pl. XIII), or by an arrow showing 
the amount and direction of dip, where these could be taken. 

The exposures of igneous rock in this district are few. They 
consist, first, of a rather thick band of diabase that crosses the 
main road between Hollybush Pass and Eastnor (M 106); this is 
apparently continued as far north as Beacon Farm, close to which 
a small exposure of diabase (M 171) is seen. Another small patch 
of diabase (M 454), associated with much indurated Grey Shale, was. 


Vol. 55.] STRUCTURE OF THE SOUTHERN MALVERNS. 165 


reached in excavations kindly made for me by Mr. Summers in a 
field south-east of Beacon Farm. 

There are, secondly, a series of bosses of basalt forming tumps 
numbered M 159a, M 108, M 249, M 248, & M 247. These 
tumps have an elongated form. The axes of M159a & M 108 
are directed about north and south; that of M 249, north-east and 
south-west ; that of M 248, north-west and south-east ; and that 
of M. 247, east-north-east and west-south-west. These bosses 
were supposed by Phillips to occur between the Malvern Shales 
and the May Hill Beds, but mapping shows clearly that they are 
situated in the Grey Shale; for beds belonging to the latter series 
occur between the bosses and the escarpment, as clearly seen to the 
west of M159a; and, in the case of M 247, the basalt is actually 
seen to be overlain by Grey Shale. 

It can hardly be doubted, from the analogy of the basalts farther 
south and from the few dips seen in the northern district (for 
instance, at M 159), that the direction of these short ridges of basalt 
marks that of the strike of the beds. The separate exposures, 
moreover, appear to be all approximately on the same horizon, with 
the possible exception of M 247, which may mark a higher 
horizon. 

In this northern district, then, a curved igneous band, consisting 
of basalts (and diabase) extends from Beacon Farm almost as far 
as Castle Coppice, and, judging from the configuration of the ground, 
it is connected with the diabase in the main road (M 106) by a 
concealed mass of similar rock. This band is undoubtedly a 
northern prolongation of the Coal Hill igneous band, which it 
resembles in being overlain and underlain by Grey Shales con- 
taming Dictyonema sociale. 


The eastern part of the Bronsil district is occupied by May 
Hull Sandstone, allusions to which may be found in the works of 
Phillips and Holl. The May Hill Beds at the north-eastern corner 
of the area are apparently a south-easterly continuation of those 
which form the north-western corner of Midsummer Hill. The 
sandstone in this locality, like that elsewhere in the Bronsil 
district, is nowhere actually exposed, and can be reached only by 
excavations. 

This sandstone is evidently separated from that forming the 
escarpment by a fault, which probably runs along the bottom of 
the valley traversing Castle Coppice; for the beds exposed in the 
escarpment on the western side of the valley are the basal beds of 
the series, and dip at a considerable angle west-north-westward, 
while those under consideration are grey beds belonging to a higher 
part of the formation. 

A second faulted patch of May Hill Sandstone occurs to the 
south. An excavation (M 192) close to a spring revealed Llan- 
dovery rock with Stricklandinia sp., and a second excavation 
{M 113) made a little to the north-west of the first furnished 


166 PROF. T. T. GROOM ON THE GEOLOGICAL [May 1899, 


Pentamerus (or Stricklandinia) sp., Leptocelia hemispherica (2), 
crinoids, and a trilobite. 

From débris a little south of Castle Coppice (M 114) I obtained 
the following fossils :—Leptocelia hemispherica, Dinobolus sp., Pen- 
tamerus sp., Beyrichia complicata, Favosites (?), and crinoids. The 
dip of the sandstone could not be determined. 

A third, much smaller, patch of May Hill Sandstone was revealed 
by an excavation made between Bronsil and Upper House Farm. 
The dip here was north-westerly at a low angle. 

The Grey Shale forming the rising ground east of Beacon Farm 
is covered by a Drift similar to that mentioned on pp. 161, 163. 


In considering the Bronsil area, it remains to be pointed out. 
that, though the observed facts agree fairly well with the view that 
the strike of the Grey Shales, when traced from south to north, 
gradually curves round from north-west through north to north- 
east and south-east, the area occupied by the shales must be 
traversed by some fault or faults (other than those indicated in the 
map, Pl. XIII) cutting out the Black Shales; for, supposing the 
latter to form a similar curve, they ought to appear both south, 
west, and north of Upper House Farm, whereas in reality Grey 
Shales are found everywhere in places not occupied by May Hill 
Beds. It is not sufficient to suppose that the blocks of May Hill 
Sandstone are simply let down into the otherwise undisturbed 
Malvern Shales ; some faulting-down of the Grey Shales themselves. 
in the eastern part of the area must have occurred. 

It may, lastly, be observed that igneous rocks appear to be much 
less developed in the Bronsil area than in the two districts to 
the south. No traces are visible of the middle igneous band, and. 
there seems to be little reason to believe that this is present, but 
not exposed, for the basalts make a very distinct physiographical 
feature in the Pendock’s Grove area; whereas smooth low ground 
appears in the Bronsil district in places where these rocks might 
be expected to occur. This igneous band seems either to have 
died out towards the north, or to have been faulted out, together 
with the Black Shales. The relative insignificance of the Coal Hill 
band rather favours the former hypothesis. 


V. Tae May Hitt Sanpstone Escarpment. 


The escarpment forming the western boundary of the Cambrian- 
shale district extends from Castle Coppice on the north to near 
Hayes Copse on the south. For most of its length it rises sharply 
from the adjoining lower ground, but between Martins and Hanging. 
Lift, and again south of High Wood, the slope is gentler. It is 
interrupted at two points by small transverse valleys which give 
passage to streams: first between Bronsil Lodge and Wain Street, 
and secondly south of Rowick. 

The dips (as shown on the map, Pl. XIII) and the strikes of the 
beds correspond approximately, so far as they are visible, with the 


Quart. Journ. Geol. Soc. Vol. LV, Pl. XIII. 


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Vol. 55.] STRUCTURE OF THE SOUTHERN MALVERNS. 167 


semilyrate form of the escarpment. The actual junction of the 
Llandovery Beds with the older series is nowhere shown, but its 
position can, in most places, be fixed within narrow limits. 

The beds immediately underlying the Llandovery Sandstone and 
Conglomerate along the whole length of the escarpment are the 
Grey Shales, or possibly, south of Martins, igneous rocks associated 
with them. Only in Castle Coppice is this natural junction 
replaced by a faulted one; a block of Llandovery Sandstone is 
here brought down against the basal Llandovery Beds of the 
escarpment. 

It is important to note that the strike of the Grey Shales is 
generally about parallel to that of the May Hill Beds above, the 
former evidently turning round through all the marked curves 
shown by the latter. In the absence of any exposures of the 
junction, it is impossible to say to what extent the amount of dip of 
the two series differs. The complete absence of the Ordovician 
formations from the district would prepare one to find a marked 
difference in this respect. The dip of the Grey Shales, however, in 
the Bronsil district (where the sandstones are best exposed) varies 
generally from 15° to 48°; that of the adjacent Llandovery Beds. 
ranges from about 17° to 60°. South of Bronsil the shales dip at 
an angle of 40°, while the sandstone not far away dips at an angle 
of 48°. These facts would seem to indicate that the dips in both 
series are of the same order, and that, were actual junctions exposed, 
the discordance between the two might not be perceptible in a 
single section. Moreover, the behaviour of the line of junction as 
it crosses the contour-lines (see map, Pl. XIII) can hardly be 
explained otherwise than by supposing that the plane of junction 
of the sandstone with the shales dips everywhere into the escarp- 
ment, at an angle approximately equal to that of the dip of the 
May Hill Series; or, in other words, that the Llandovery Beds 
overlie the older series, with probably apparent conformity. 

In this connexion it must, however, be noted that, if (as is 
practically certain) the main igneous belt in the Bronsil district 
corresponds with the Coal Hill band of the districts on the south- 
east, the beds of this horizon are appreciably nearer the 
escarpment in the northern than in the southern part of the 
‘ Western Tract.’ The line of igneous bosses in the Upper Grey 
Shales (M 101, 101 a, & 102) approaches very near the escarpment 
south of Martins, while on the north there seem to be no indi- 
cations of its existence, unless M 247 denotes its reappearance 
towards the east. This zone has probably passed underneath 
the May Hill Beds north of Martins. Moreover, the area occupied 
by the Upper Grey Shales broadens out towards the south, as seen 
south of Coal Hill. These facts probably indicate that, as the 
unconformable junction is followed from north to south, newer beds 
belonging to the Grey Shales gradually make their appearance, 
the Llandovery Beds slowly overstepping the zones of the Grey 
Shale when traced northward. 

On the other hand, there is no evidence of an overlap of the 


Quart, Journ. Geol. Soc. Vol. LY, Pl. XIII. 


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168 PROF, T. T. GROOM ON THE GEOLOGICAL [May 1899, 


Llandovery Beds when traced towards the Malvern range itself 
(that is, towards the east), for near the southern end of Chase End 
Hill, and near Castle Coppice, close to Midsummer Hill, the Llan- 
dovery Beds rest on zones of the shale as high as, or higher in the 
series than, the shales beneath the escarpment near Bronsil. 

The current statement that the Llandovery Beds transgress across 
all the Cambrian zones into the Archean must, therefore, in my 
opinion, be modified. 


It is proposed to supplement the present communication by 
further papers dealing with other portions of the Malvern and 
Abberley ranges, and with the stratigraphy, paleontology, and 
lithology of the rocks considered. 


EXPLANATION OF PLATES XIII-XV. 


Prats XIII. 


Geological Map of the Southern Part of the Malvern Hills, on the scale of 
4 inches to the mile. 


Puatse XIV. 


View of Raggedstone Hill from the south. 

The observer is supposed to be standing onaspur of Chase End Hill (at 
the spot marked 269 in the map). The village of White-leaved Oak is per- 
ceived near the middle of the view, situated partly on an igneous band 
which forms the series of gentle swellings running south and north-west 
of the houses seen. The western edge of this ridge is seen to the left of 
the haystack, and in the distance is marked by a large tree at the northern 
corner of Pendock’s Grove. The eastern limit of the Black Shales is marked 
approximately by the trees at the top of the field on the western slope of 
Raggedstone Hill. The Hollybush Sandstone forms most of this slope, 
the upper limit being indicated approximately by the top of the sharp 
ridge above the village, and by the trees farther north-west. The depres- 
sion marking the axial thrust-plane is well seen beyond this line, passing 
between the two summits of the hill. 


PLATE XV. 


View of the Hollybush Pass and Midsummer Hill, from the hollow known as 
Winter Combe, on the northern slope of Raggedstone Hill. The axial 
depression forming this hollow is continued beyond the pass to the left of 
the quarry (schists) between Hollybush Hill on the right and Midsummer 
Hill on the left. The observer is standing on the small quartzite-ridge, 
the chief rock-exposure of which occurs by a small hollybush seen in the 
bracken. ‘To the left of the houses, near the centre of the view, is seen 
the bank in which the May Hill Sandstones are faulted against the Archzan 
diorite. 


Discussion. 


Dr. Hicks said that the faulted conditions at the margins of the 
erystalline rocks in the Malvern Hills agreed in a marked manner 
with those along the borders of the pre-Cambrian crystalline rocks 
at St. David’s and in other areas in Wales. Before Holl showed 
that these rocks in the Malvern Hills were of pre-Cambrian age, 
they were supposed to be metamorphosed Cambrian sediments. 
Similar rocks in Wales were stated to be either metamorphosed 


Quart. Journ. Geol. Soc. Vol. LV, Pl. XIV. 


Tt CRO OCO 82 PROCTOR OPED ERE I ON? eRe TRRRRET ee RORCRRTORRT eee hem renee 


VIEW OF RAGGEDSTONE HILL FROM THE SOUTH (see Explanation). 


Quart. Journ. Geol. Soc. Vol. LV, Pl. XV. 


VIEW OF MIDSUMMER HILL FROM THE RAGGEDSTONE, LOOKING NORTH (see Explenation). 


Vol. 55.] STRUCIURE OF THE SOUTHERN MALVERNS. 169 


deposits of Cambrian or Silurian age, or intrusive masses invading 
Cambrian or Silurian rocks. In each case, the mistake seems to 
have been mainly due to the fact that the observers had failed to 
recognize the remarkable results produced by faults and crushing, 
not only on the sedimentary beds in the immediate neighbourhood 
of the pre-Cambrian crystalline rocks, but also on the latter, during 
intense movements in the earth’s crust. 

Prof. Sottas remarked that ever since Phillips had made the 
Malverns the base of the district described in his ‘Geology of 
Oxford & the Valley of the Thames,’ those mountains had been a 
source of peculiar interest in Oxford, and the Author’s work had 
been looked forward to with great expectations, which the paper of 
that evening had more than satisfied. It presented them with 
an epitome of mountain-structure, logically worked out, even 
the transverse fractures, which must necessarily result in crust- 
folding, receiving the attention which they merited, but rarely 
obtained. ‘The examples of ‘ basalt’ exhibited did not appear to be 
typical examples of that rock; and since nearly every petrographer 
used the term ‘diabase’ in a different sense, the speaker thought 
that this name should not be employed without some qualification. 
With regard to the nodes and internodes of the West English chain, 
it was possible that the two systems of crossing folds which produced 
them might have been simultaneous, and not successive. 

Prof. Warts referred to the igneous rocks associated with the 
Cambrian rocks of the Malvern Hills, and noted their resemblance 
to those originally described by Allport as diorite in Warwickshire. 
Similar rocks occur in association with Cambrian strata at Nuneaton, 
the Longmynd, the Wrekin, and in the Northern Highlands. 

The Presipent, Prof. Larpwortu, Prof. Bonney, and Prof. Hurt 
also spoke. | 

The AvtHor said, in answer to Prof. Sollas and Prof. Watts, that 
the terms ‘ basalt’ and ‘ diabase * were employed in the sense used 
in Mr. Harker’s ‘ Petrology for Students.’ To Prof. Lapworth he 
replied that he hoped to deal in a later communication with the 
movements which the Malvern chain had undergone. 


170 MR. F. RUTLEY ON FELSITIC LAVAS [May 1899, 


9. On a Smauu Sxctrion of Frrstric Lavas and Turrs near Conway 
(CAERNARVONSHIRE). By FRranx Ruruzy, Esq., F.G.S. (Read 
January 18th, 1899.) 


[Map on p. 172, and section on p. 174.] 


Tue felsites of Conway Mountain were described by Prof. Bonney 
more than 16 years ago." Among specimens which I collected in 
North Wales in 1877, but from which sections have only recently 
been prepared, there are a few which may be of interest, since they 
were procured at short intervals from a point at the mouth of the 
River Conway, and may be regarded as representing the southern 
portion of the felsite near the fault which, on the Geological Survey 
map, is shown to separate the felsites of Conway Mountain from 
those of Diganwy, throwing the latter a considerable distance to 
the north. 

The spot at which the specimens were collected is marked Bod- 
londeb on the Ordnance Survey map. A path runs round this point, 
bounded on the west by an exposure of rock which has been dressed 
back so as to form a low natural wall, while a lower wall has been 
built between the eastern side of the path and the estuary (see 
map, p. 172). The specimens, or small chips, were consecutively 
numbered in the order in which they were collected, from south to 
north. On the south the felsite is succeeded by Bala Beds, which 
about amile to the west are marked on the Geological Survey map: 
as dipping 60° southward, but at Bodlondeb the felsites appeared to 
dip at a higher angle. 


No. 1 is a pale pinkish-grey rock, somewhat resembling the 
yellowish felsite which occurs to the west below Castell Caer Seion. 
The fluxion-structure is, however, more delicate and better defined. 
The bands are not continuous, but extend only for short distances, 
thinning away towards their extremities. They are cryptocrystalline, 
and are more translucent than the rest of the rock, which has, as a 
rule, a microcrystalline character, and is rendered turbid by diminu- 
tive grains and flecks of opaque white matter, the latter apparently 
due to the kaolinization of the felspathic constituents. The structure 
may be defined as an impersistently banded, wavy fluxion. 


No. 2, taken some 10 or 15 feet farther north than the pre- 
ceding specimen, is a pale bluish-grey rock, consisting of felsitic 
matter, sufficiently coarse in texture to permit the investigation of 
individual grains in convergent polarized light. Some of the grains 
show a positive uniaxial interference-figure: these are quartz. 
Other grains, also colourless, show the emergence of a bisectrix or 
else a dark brush which sweeps obliquely across the field during 
rotation: these are grains of felspar, and they seem to be more 
numerous than those of quartz. In transmitted light, the section 
shows an irregular, hazily-defined fluxion-structure ; while, between 


1¢QOn some Nodular Felsites in the Bala Group of North Wales,’ Quart. 
Journ, Geol. Soc. vol. xxxvili (1882) p. 289. 


Wols5 | AND TUFFS NEAR CONWAY. ae 


crossed nicols, this is barely if at all apparent, being obliterated by 
the mosaic formed by the coarse grains of the felsitic matter. 
Pseudomorphs of cryptocrystalline matter after felspars, white 
opaque particles which appear to be kaolin and limonite, with a few 
small specks of unaltered pyrites, may also be seen in this section. 


No. 3 is a pale pinkish to yellowish-grey nodular felsite. 
Only one specimen was collected, containing a single nodule about 
17 inch in diameter and of a plano-convex form, somewhat re- 
sembling the head of a mushroom. ' A section was made through 
the centre of this nodule in a vertical direction, but in the process 
of grinding the nodule became separated from the surrounding 
felsite. The latter is characterized by an extremely beautiful 
damascened fluxion-structure, the bands being corrugated and pro- 
ducing a mottle like that on a gun-barrel or a Damascus blade. 
It contains granular patches of a pink or white opaque substance, 
about the nature of which I do not venture to speculate. The 
nodule is solid throughout, and possesses an irregular, undulating, 
banded fluxion-structure: the bands, although, in places, more or 
less folded, passing in a comparatively straight, general direction 
through the nodule, and exhibiting far less plication than the 
banding in the surrounding rock. From this the nodule differs in 
translucency, a circumstance which seems to be mainly due to an 
impregnation of chlorite in extremely small scales. Numerous clear 
spots, mostly oval or circular, occur in the section of this nodule. 
In most cases they consist of small aggregates of crystal-grains 
with, usually, scales of chlorite, and afford no satisfactory inter- 
ference-figures ; but in one or two instances they show a positive 
uniaxial figure in convergent light, and are probably quartz. A 
hazily-defined, nearly semicircular band can be seen in the section 
on viewing it with the naked eye against the light, but this, 
under the microscope, shows no definite boundaries and merely seems 
to differ from other parts of the nodule in containing less chlorite. 
A few minute cracks, now sealed, either traverse the nodule or pene- 
trate for short distances from its surface. Being a solid nodule, 
it seems to have originated by contraction on cooling, but whether 
the segregation of matter now represented by chlorite had anything 
to do with the formation of the crack which separated this nodule 
from the surrounding lava is a question which I am unable to 
answer. ‘There appears to be no distinct evidence of the divergent 
fibrous structure which so frequently characterizes spherulites. 
Prof. Bonney has already described lithophyses both from Conway 
Mountain and from Diganwy. ‘Some of the nodules described by 
the same author as occurring above the Conway Falls Inn are 
stated by him to be ‘solid to the core,’* as in this example. There 
seems no evidence that the small clear patches in this nodule are 
or ever were vesicles. The rock isa devitrified obsidian. 


No. 4 isa rather dark, purplish-grey rock. This is seen under 
the microscope to be a felsite, with barely perceptible fluxion- 


1 Op. cit. pp. 298, 294. 


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Woll 55. | FELSITIC LAVAS AND TUFFS NEAR CONWAY. 173) 


structure. It is charged with a considerable amount of limonite 
and chlorite, the latter mineral often forming fan-shaped groups 
of crystals filling irregularly-shaped vesicles. It contains nume- 
rous crystals and fragments of an opaque white mineral which 
appears to be leucoxene, and, if so, represents, in most cases, 
the complete alteration of ilmenite. The white patches are seen 
in reflected light to be traversed by well-defined cleavages, which 
sometimes intersect at 60°, and may indicate the rhombohedral 
character of the original mineral. The limonite is pseudomorphous 
after magnetite, or perhaps in some cases after pyrites. A few 
fragments, possibly of porphyritic felspars, are now represented 
partly by chlorite and partly by microcrystalline felsitic matter. 
Microlites are numerous in the rock. They do not appear to 
have any definite linear arrangement, and they mostly give 
approximately straight extinction, but others show inclined 
extinction: some of them are probably oligoclase. There also 
appears to be a small amount of brown devitrified glass present 
in the section. The rock seems to have a tufaceous character, and 
should be called a tufaceous rhyolite, not a rhyolite-tuff. 


No. 5 is a deep purplish-grey felsite, somewhat similar to the 
preceding rock. On examining the section under the microscope the 
rock, like No. 4, is seentobe a tufaceous rhyolite. The frag- 
ments are to a large extent derived from rhyolites or devitrified 
obsidian, but they vary, some being colourless, while others are of a 
coffee-brown tint, occasionally showing delicate fluxion-banding.. 
There are also fragments of opaque rock, some pale, others dark 
brown, but their precise nature is difficult to determine. The rock 
may be regarded as a rhyolite which, prior to its solidification, 
has enveloped fragments of rock, some vitreous, others lithoidal. 
Among the fragments is a rounded piece of quartz composed of 
four or five individual crystals differing in orientation, and one of 
them is cut nearly at right angles to the optic axis. This aggregate 
of quartz contains many liquid inclusions with bubbles: some of 
the latter show spontaneous motion under a high power. 


No. 6. A deep greenish-grey to reddish-brown rock. This is a 
remarkably fine example of a devitrified obsidian with corru- 
gated fluxion-structure, emphasized by a banding of dark-brown with 
colourless glass. Obsidians of comparatively recent date, consisting 
of bands of glass which differ in colour, are well known, notably in 
the Yellowstone district, where there are brownish-red obsidians 
which, in thin section, are seen to consist of bands and threads of 
orange-red alternating with colourless glass. Concerning these 
obsidians, Prof. Iddings remarks :—‘ The transition of the yellow 
and orange bands into black grains, the larger of which are recog- 
nizable as magnetite, indicates that the former are made up of 


Note.—The lines B, C, and D on the map (p. 172) are merely intended to 
suggest a possibility, and are mainly based upon inference. All the other 
geological lines are copied from the 1-inch Geological Survey map (78 N.E.), 
published in 1852. Owing to the small scale of that map, it was scarcely 
possible that it could represent the felsitic lavas in greater detail. 


174 MR. F. RUTLEY ON FELSITIC LAVAS [May 1899, 


finely divided particles of iron more highly 
oxidized, which is confirmed by the chemical 
analyses of the red and black obsidian. The 
iron in the red variety is almost wholly sesqui- 
oxide, while in the black obsidian there is a 
slight excess of protoxide over that required to 
form magnetite in combination with the sesqui- 
oxide.’* Ina paper published many years ago ? 
one of the reddish-brown obsidians from the 
Yellowstone district was described, and it was 
there mentioned that rocks of a similar nature 
were to be met with in North Wales. This 
devitrified obsidian from Bodlondeb is a good 
example, what were possibly once red bands 


Rhyolitic Tuff 


GS 

26 being now represented by devitrified brown 
&3 glass. Such a change in colour would naturally 
26 result from the action of water upon the ferric 


oxide which originally gave its colour to the 
glass, converting it into hmonite. The section 
contains porphyritic crystals of orthoclase 
(sanidine), twinned on the Carlsbad type, but 
much altered and kaolinized, and in some cases 
containing brown devitrified glass. I am in- 
clined to believe that in this section there is an 
extremely small quantity of unaltered glass, an 
observation which, if correct, taliies with that 
of Prof. Bonney in the case of another rock in 
the same neighbourhood.® 


acre 


No. 7 is a deep greenish-grey rock con- 
taining reddish-brown fragments, one of them ° 
which projected from the surface of the specimen 
having measured over 4 inch in length before 
cutting. Under the microscope the section is 
seen to consist to a great extent, if not almost 
wholly, of fragments, the majority of them 
being devitrified obsidian. or rhyolite, some 
colourless, others reddish-brown. Some opaque 
‘white crystals and fragments, which in some 
instances may be kaolin, in others leucoxene, 
are present in this section. It is difficult to 
decide whether the fragments are embedded in 
a rhyolitic lava or whether the entire rock 
consists of fragments. If the latter be the 
case, the rock is essentially a rhyolite-tuff. 
The devitrification of some of the fragments 
is globulitic, and occasionally the globulites are 


Tufaceous Rhyolite 
[Approximate horizontal scale: 3 inches = 100 yards. ] 


Diagrammatic section of the rhyolite serves at Bodlonded. 


Nodular 
Devit.Obsid. 


Rhyolite 


1 «Obsidian Cliff” U.S. Geol. Surv. 7th Ann. Rep. 1885-86 [1888] p. 274. 

2 «The Microscopic Characters of the Vitreous Rocks of Montana,’ Quart. 
Journ. Geol. Soc. vol. xxxvii (1881) p. 392. 

3 Quart. Journ. Geol. Soc. vol. xxxvili (1882) pp. 294-95. 


Vol. 55.] , AND TUFFS NEAR CONWAY. 175 


segregated into cumulites. In other fragments the devitrification 
is partly microlitic and partly globulitic. There are also a few very 
obscure indications of a small spherulitic structure, but in no 
instance is there any trace of perlicity. 


Using the more recent nomenclature, the lavas described in — 
this paper would be termed eorhyolites by some petrologisis, 
aporhyolites by others. I have, however, simply employed the 
name rhyolite for such lithoidal rocks as may originally have had 
either a lithoidal or vitreous character. Since they are now hithoidal, 
they differ in no respect from recent rhyolites or lithoidites, but in 
cases where the rock was once an apparent obsidian I have called it 
a devitrified obsidian. All of these rocks are embraced under 
the general term felsitic lavas. 

Between the two nodular beds, noted by Prof. Bonney, it is at 
present impossible to say how many similar beds, if any, occur, 
but a more minute investigation of this intermediate area might 
yield interesting results. 

The foregoing paper must be regarded merely as a small appendix 
to Prof. Bonney’s work in the vicinity of Conway, but I trust that 
it may serve to confirm some of his statements. The observations 
which he has made upon the felsites of Diganwy and their relation 
to those of Conway Mountain open up questions which can only be 
solved by mapping those portions of the district on a larger scale 
than that of the l-inch map. 


Discussion. 


Prof. Bonney expressed his gratification at the Author’s return 
to work, and was glad to find that he did not differ materialiy 
from the results which the speaker had obtained several years ago. 
He quite agreed that it was sometimes very difficult to distinguish 
between fragmental acid volcanics and acid lavas with flow- 
brecciation. He distinctly remembered the occurrence of nodular 
felsites at Diganwy, but had not attempted to work out the strati- 
graphy, because he was investigating a special question, namely, 
the origin of the nodular structure. The Author had evidently 
studied a set of rocks closely resembling those examined by the 
speaker, and the latter thought it possible that he might have 
touched one end of the Author’s section. 

Lieut.-Gen. McManon congratulated the Author on his lucid and 
interesting paper. He agreed with him that it was sometimes 
extremely difficult to distinguish between a lava that had caught up 
numerous fragments of an ash, and an ash-bed the fine matrix 
of which had been much altered by aqueous infiltration or contact- 
metamorphism. In such cases a large series of specimens was 
necessary, to enable the petrologist to ascertain with any confidence 
the true character of the rock. 

The Presipent, Mr. Harker, and Mr. Srrawan also spoke. 

The AvrHor, in reply, said he was glad to find that Prof. Bonney 
was able to confirm many of his statements. It was to his 


176 FELSITIC LAVAS AND TUFFS NEAR CONWAY. [May 1899, 


admirable paper on nodular felsites that the Author was so largely 
indebted. The cutting at Bodlondeb was possibly not made when 
the district was originally mapped by the officers of the Geological 
Survey. With Gen. McMahon’s observation, as to the resemblance 
of sections of highly-altered tuffs with those of lavas which had taken 
up rock-fragments, he fully agreed. Inreply to Mr. Harker’s query, 
whether those rocks which were described in the paper as having 
been originally obsidians were really devitrified glass, he explained 
that such a conclusion was possible, although difficult of demon- 
stration, since very slight alteration often sufficed to impart a 
thoroughly lithoidal character, and such alteration might supervene 
very soon after the solidification of an obsidian. Mr. Strahan’s 
remark that lava-flows accompanied by tuffs occurred south of the 
general mass of felsite constituting Conway Mountain was very 
interesting, as the occurrence had seemingly been overlooked 
hitherto. 

In conclusion, he thanked the President and the Fellows for 
their cordial reception of his paper. 


a 
/ 


Vol 55.1 THE OCEANIC DEPOSITS OF TRINIDAD. 17 


10. The Oczantc Deposits of Trintpap (Britiss West Inprzs). 
By Prof. J. B. Harrison, M.A., F.G.S., F.C.S., & A. J. JuKEs- 
Browne, Esq., B.A., F.G.8. (Read January 4th, 1899.) 


I. Histortcat Inrropuction. 


[By A. J. Juxzs-Browye. | 


Tue object of this communication is to present some observations 
on the succession and geological relations of the beds which have 
long been known in Trinidad as the Naparima Marls. This 
name was given to these beds by Wall & Sawkins in 1860,’ on 
account of their occupying a large part of the Naparima district, 
east and south-east of San Fernando (see map, fig. 1, p. 182). 

The beds so named formed one of the five series which were 
described by these authors under the head of the ‘ Newer Parian 
Group.’ The names given to these five series were (a) Nariva 
Series, (6) Naparima Marls, (c) Tamana Series, (d) Caroni Series, and 
(e) Moruga Series; but it was explained on a subsequent page * that 
these subdivisions do not form a definite succession. The Nariva 
Series occupies a central or axial position, and this Wall & Sawkins 
considered to be the oldest. The Tamana and the Caroni Series 
occur only to the north of it, while the Nariva and the Moruga lie 
on the southern side, and they thought that these two sets of 
deposits might be correlative one with another, the Nariva corre- 
sponding to the Tamana and the Moruga to the Caroni Series. 

In their general section across the island from north to south, 
Wall & Sawkins show the Nariva Beds dipping southward below 
the Naparima Marls, and the latter passing in the same direction 
beneath the Moruga sands; while still farther south they indicate 
a syncline occupied by Naparima Marls which rest directly and 
unconformably upon the ‘ Older Parian rocks’ (Neocomian). Thus, 
in the opinion of the above-mentioned authors, the sequence within 
their Newer Parian Group was as follows :— 

(3) Caroni—Moruga Series. 
(2) Tamana—Naparima Series. 
(1) Nariva Series. 


They describe the Naparima Marl as ‘a series... composed of 
marls, conglomerates, and calcareous sand.’ They speak of the 
marls as fine-grained deposits varying from argillaceous marls to a 
deposit with ‘a basis of siliceous substance, consisting of the shields 
of infusoria’ with about 20 per cent. of carbonate of lime. They 
state further that ‘ the best agricultural variety is the white marl 
of South Naparima, which is very light, softer than chalk, and of an 
extremely white colour.’* It is therefore perfectly certain that what 
are now known to be radiolarian and diatomaceous marls constitute 
an essential part of the Naparima Marls. 

The position of the conglomerates is not indicated, except that 

' Mem. Geol. Surv. ‘ Report on the Geology of Trinidad,’ p .35. 
2 Ibid. p. 59. obs pe 3. 
Q.J.G.8. No. 218. N 


178 MESSRS. J. B. HARRISON & A. J. JUKES-BROwWNE [May 1899, 


they were seen in a gravel-pit on the Fairfield Estate, and, as they 
have never since been recognized, they can hardly be a conspicuous 
member of the series. It is stated that ‘the cliffs of marl for some 
distance north and south of San Fernando contain pure asphalt in 
the fissures or joints’’*; and the extent of the Naparima Marls is 
shown in the geological map which accompanies the Report. 

In 1866 Mr. R. J. L. Guppy, in a paper on ‘The Relations of the 
Tertiary Formations of the West Indies,’ referred to the five groups 
above mentioned, and wrote :—‘ Of these the strata exposed at San 
Fernando, which were probably included in the Naparima Marls, 
and those classified as the Tamana Series, seem to me to be the 
oldest.’* He gives details of the cliff-section south of San Fernando 
and a small diagram-section, to show the general succession of rock- 
eroups. It is noticeable that in this section the Nariva Series does 
not appear, and that the San Fernando Beds seem to take its place. 

In 1872 Mr. Guppy announced that some of his San Fernando 
Beds were really foraminiferal marls?; these he regarded as a 
continuation of the beds in which he had found Nucula Schomburgki, 
and he proposed to call them the Nodosarza-beds, believing the 
whole series to be of Lower Miocene age. In 1874, however, other 
evidence made him regard them as Hocene. 

From a still later paper * it would seem that Mr. Guppy really 
intended to separate the San Fernando Beds from the Naparima 
Marls, for he refers the former to the Eocene and the latter to the 
Miocene, and considers the probable order of succession to be as 
follows :— 

MOnUG A SCTICS 4. f.e. a-n <n sbeaapeese nce = Pliocene. 

Caroni, Nartva, & 
Naparima Beds 

Tamasa & San Fernando Beds ...... = Hocene. 


It is to be noted that, up to 1892, Mr. Guppy had described only 
the coast-section (in which the radiolarian rocks are not seen), and 
had never discussed the geological relations of the beds existing in 
the typical Naparima district. In the meantime Prof. Harrison 
had visited this district, and had been impressed with the similarity 
of the deposits to those which he had examined in Barbados, the 
white marls of Naparima corresponding to the radiolarian marls of 
Barbados and seeming to rest unconformably upon a series of clays 
and sandstones which were comparable with the Scotland Beds of 
the other region. This view of their relative position was published 
in a joint paper by Prof. Harrison and myself on the Oceanic Series 
of Barbados.’ 

In the same year Mr. Guppy communicated a paper to this 
Society ° in which he stated the conclusions at which he had then 
arrived with regard to ‘ the stratigraphy of the Naparima Beds.’ In 
this paper he entirely abandons the name of San Fernando Beds, 

1 Mem. Geol. Surv. 1860, ‘ Report on the Geology of Trinidad,’ p. 37. 
2 Quart. Journ. Geol. Soe. vol. xxii. p. 571. 

5 Geol. Mag. 1873, p. 362. 

4 Proc. Sci. Assoc. Trinidad, pt. xi (1877) p. 113. 

° Quart. Journ. Geol. Soc. vol. xlviii (1892) p. 218. 8 Ibid. p. 519. 


iianee as ee = Miocene. 


Wolsis5e| ON THE OCEANIC DEPOSITS OF TRINIDAD. 179 


and uses the name Naparima Beds for the whole series seen in 
the cliffs, from a little south of the Taruba Creek to the Oropuche 
Lagoon, south of San Fernando. As he refers to the statement 
made by Wall & Sawkins that marls belonging to their Naparima 
Series are exposed in the cliffs both north and south of San Fernando, 
and as he evidently thinks that the beds are parts of one continuous 
series and are all of Eocene age, one must suppose that he con- 
sidered the older name to have the priority. 

In his diagrammatic section of the beds seen in the cliffs he 
numbers separate portions from 1 to 18 (op. cit. p. 522). Of 
Nos. 1 & 2, which adjoin Taruba Creek, he says that they ‘appear 
to belong to the Nariva Series of the Geological Report, supposed 
to be inferior in position to the Naparima Marls of that Report.’ 
He, however, inclines to regard them as superior to the ‘ Eocene 
Naparima Marls’ and refers them to the Miocene. From a later 
sentence, and from remarks in a previous paper, it would appear 
that he does not limit this opinion to the clays of Taruba Creek, 
but regards the whole Nariva Series as superior to the Naparima, 
and as (partly) the equivalent of the Caroni Series, which lies on 
the northern side of the central ridge. 

Returning to the series which in the paper that we have just 
quoted Mr. Guppy calls ‘ the Naparima Beds,’ including therein the 
San Fernando Beds of his previous papers, we find that it comprises 
a number of different rock-groups, clays, marls, shales, and lime- 
stones of various colours. They are tilted up at high angles and 
are broken by numerous faults, and thus from a mere inspection of 
them it is impossible to be sure that they belong to one series or 
group of beds. Their community of age could be proved only by 
a community of fossils, and Mr. Guppy makes no endeavour to show 
that such is the case. 

Moreover, taking Mr. Guppy’s own description, the beds seem 
to separate themselves naturally into two groups. Thus, he de- 
scribes Nos. 3 & 4 as ‘a series of red, black, and variegated marls 
[? clays]... which contain bands of limestone . . . with fossil mollusca 
similar to those in No. 7.’ He considers these beds to be repeated 
farther south at Bontour Point, where they are brought up by a 
fault and are numbered 6,7, & 8. ‘These beds are succeeded by 
No. 9, called ‘the Nucula-beds,’ aud elsewhere described as hard 
marls and blue clays. These numbers form one group, and they 
include all the beds which yielded the fossils previously found 
by Mr. Guppy and for which he claims an Kocene age. 

The other group includes Nos. 5,10, 11, 12, 16, & 17; these 
are all Globigerina-marls, containing a large foraminiferal fauna, 
which, however, does not include the Nummultes and Orbitoides 
found in the first group. The fauna is essentially a deep-water one, 
and has no connexion with the fauna of the true San Fernando Beds. 

Nos. 13 & 14 arespaces where no beds are seen. No. 15 isa shell- 
bed, the relations of which are doubtful; but it certainly belongs 
to a shallow-water formation. No. 18 indicates the supposed 
position of the radiolarian earths beneath the Oropuche Lagoon. 

N 2 


180  MBSSRS. J. B, HARRISON & A. J. JUKES-BROWNE [May 1899, 


He gives some account of Naparima Hill, which is close to 
San Fernando, but says very little of the Naparima district, where 
the radiolarian marls are found." He mentions some exposures of 
them in South Naparima, but none which showed their junction 
with the foraminiferal beds. In his tabular arrangement, however 
(op. cit. p. 538), he places the radiolarian beds at the top, as part of 
the Miocene, and connects the Globigerima-marls with the Eocene 
beds of San Fernando, while the argiline of Naparima Hill is put 
still lower, as the top of the Cretaceous. Thus these three sets of 
beds are regarded as belonging to three separate formations, widely 
different in age. 

Mr. Guppy has contributed largely to our knowledge of the rocks 
of Trinidad, and has furnished us with valuable lists of their fossil 
contents, but from the foregoing résumé it will be seen that his 
writings leave both the nomenclature and the succession of the 
Trinidad Tertiaries in a very uncertain state. 

First, with regard to the nomenclature. When, in 1866, 
Mr. Guppy described the San Fernando section, he was quite 
justified in separating the beds in which he then found fossils from 
the rest of the Naparima Marls, and in giving them a separate 
name. Again, when at a later date he found a different set of 
fossils in certain other beds, he very properly proposed to give them 
also a special name, the Nodosaria-beds. In 1892, however, 
he seems to have assumed that these two sets of beds were parts 
of one continuous series, and.that they formed part of the Naparima 
Series of the Geological Surveyors. Hence he abandoned his own 
names, and reverted to that given by Wall & Sawkins. 

The question now, however, is not whether those authors meant 
to include certain beds at San Fernando in their Naparima Marls, 
but whether these particular beds really belong to the same for- 
mation as the typical marls of Naparima. If they do not, and if 
there is an unconformity between the two sets of deposits, then it 
is obvious that the name Naparima Marls must be restricted 
to the Globigerina-marl|s and radiolarian beds alone, and that the 
San Fernando Beds must retain their name as part of a much older 
formation. 

Next, with regard tothe general succession, Mr. Guppy considers 
the Nariva Series to be newer than any part of the Naparima Beds ; 
but the dark clays which occur in the Naparima district were 
mapped as Nariva Beds by Wall & Sawkins, and were regarded 
by them as underlying the ‘ infusorial earths.’ 

Three definite issues are thus raised—(1) Are the Nariva Beds 
above or below the Naparima Marls? (2) Do Globigerina-marls 
occur in the Naparima district ; and, if so, are they connected with 
the radiolarian marls, or are they part of a separate formation ? 
(3) What is the relation between the San Fernando Beds and the 
other groups ? 

Prof. Harrison’s observations were made in May 1895, but he 

1 Two samples of radiolarian earths are, however, described in an appendix 


by Dr. J. W. Gregory, from specimens sent to him by Mr. Guppy, Quart. 
Journ. Geol. Soc. vol. xlviii (1892) pp. 538-539. 


Vol. 55.] ON THE OCEANIC DEPOSITS OF TRINIDAD. 181 


postponed their publication in deference to Mr. Guppy’s request, 
that gentleman having then recently become aware of sections in 
South Naparima which showed a passage between the Gilobigerina- 
beds and the radiolarian earths, and desiring to publish the fact 
himself. It was not, however, till May 1897 that a note on the 
subject was read to the Victoria Institute of Trinidad, and not till 
August 1898 that this was published. In it Mr. Guppy briefly 
mentions that certain exposures show a gradual transition from the 
Globigerina-marls (which he calls the Foraminifera-beds) to 
the radiolarian beds, but he does not in any way discuss their other 
stratigraphical relations. He remarks that the junction-beds are 
intermediate in character as well as in position, and he gives a 
list of some of the foraminifera which they contain, noting that 
‘the abundance of Lagena is remarkable,’ * 

Thus Mr. Guppy and Prof. Harrison agree in giving the same 
answer to the second of the questions above mentioned, but, as 
will be seen in the sequel, with regard to the Nariva Beds, 
Prof. Harrison differs entirely from Mr. Guppy and agrees with 
Messrs. Wall & Sawkins; lastly, he has formed the opinion that 
the San Fernando Beds are closely connected with, and are probably 
an upward continuation of, the Nariva Series. He is thus able to 
present us with a clearer view of the succession in Trinidad, and to 
correlate the several groups with those in Barbados. 


Il. Tae Grotocicat Succession In THE NapParimMA District. 
[By J. B. Harrison. | 


Tux existence of radiolarian beds in Trinidad has been known for 
some time, and with respect to their geological position the 
observations made by Mr. G. F. Franks and by myself? were in 
accordance with those of Wall & Sawkins, as expressed in their 
‘Report on the Geology of Trinidad’ (1860). They regarded the 
radiolarian beds as overlying the Nariva Series, and we took the 
same view, with the further opinion that the one series was un- 
conformable to the other. Mr. Guppy, on the other hand, could not 
find any evidence of superposition, and expressed the opinion that 
‘this Nariva Series is not inferior to the Eocene marls of Naparima, 
but superior to them .. . and partly the equivalent (on the southern 
side) of . . . the Caroni Series on the northern.’ ® 

lf Mr. Guppy’s opinion were correct, the succession in Trinidad 
would be so different from that in Barbados that no comparison 
could be made between them. I therefore availed myself of an 
opportunity which occurred early in 1895, and spent several days 
in examining the exposures in the Naparima district. The geology 
did not appear to be at all complex, the beds seen being (1) red 
and blue clays referable to the Nariva Series of Wall & Sawkins, 
(2) grey Globigerina-marls acknowledged by Mr. Guppy to be of 

1 Proc. Victoria Inst. Trinidad for 1897 [1898] p. 171. 


2 See Quart. Journ. Geol. Soc. vol. xlviii (1892) p. 218. 
S Ibid. p: 521. 


182 MESSRS. J. B. HARRISON & A. J. JUKES-BROWNE [May 1899, 


the same age as those of the coast-section, and (3) radiolarian beds 
similar to those of Barbados. To avoid misconception, I shall 
speak of the latter two as Oceanic Beds and of the first as the 
Nariva Beds. 

No sections were seen showing the junction of the two formations, 
but there appeared to me to be abundant evidence that the two 
series occupied the relative positions assigned to them by the 
Geological Surveyors. This is especially clear in the many railway- 
cuttings through the Ste. Madeleine Estates of the New Colonial 
Company and also near Princestown (see map, fig.1). The cuttings 


Fig. 1.—Map of the Naparima District. 


i , L/, 7 
7 


-.-....______ Prof. Harrison’s routes in 1888 and 1895. 
Alluvium Oceanic Deposits 


SS Nariva Series 


[Scale : 1 inch=about 5 miles.] 


The geology is taken direct from Wall & Sawkins’s map; the topography is 
traced (by permission) from a new map in the possession of the Colonial 
flice. 


and the deeper valleys traverse the clays and variegated marls of 
the Nariva Series, while the hills are capped with the light- 
coloured Oceanic marls. 

Towards the east, between the Ste. Madeleine Usine and Princes- 
town, the marls contain rather more argillaceous than calcareous 
maliter, while towards the south-west, from Ste. Madeleine to 
Hermitage Estate, more calcareous beds are seen passing gradually 
and laterally into calcareo-siliceous marls ; and, finally, near the 
outcrop of the deposit above the Oropuche Lagoon, in the neighbour- 
hood of Cedar Grove and Hermitage, into siliceo-calcareous beds. 

At Princestown, the lower beds, judging from specimens collected 


I a 


le I SO 


Wolk: 55. ON THE OCEANIC DEPOSITS OF TRINIDAD. 183 


in the graveyard and from a roadside-trench, consisted of a buff- 
coloured, very friable Globigerina-limestone, overlain by a cream- 
coloured Globsgertna-marl. The exposures on the road from 
Princestown to Ste. Madeleine (mostly only in the roadside 
drainage-trenches) were of ochreous-yellow, cream-coloured, and 
light-grey Globigerina-marls. 

At Ste. Madeleine Usine, at the time of my visit, a fine section 
was exposed at the side of the factory below the Hstate-house, 
showing the lower beds of the foraminiferal deposits, while a few 
yards off, and 30 feet lower on the opposite side of the works, was 
a small exposure showing the clays of the Nariva Series. The lower 
beds of the foraminiferal deposits do not consist, as in Barbados, of 
a pure white or almost white chalk, but of a greyish-blue marl, 
through which abundance of almost white spheres of Globigerina 
are clearly visible to the naked eye. These marls are overlain by 
cream-coloured beds of Globigerina-marl, weathering to a lighter 
hue. 

Many exposures of the underlying clays of the Nariva Series 
were examined on the various lines of railway running through the 
Ste. Madeleine Estates; these generally showed red, blue, and 
mottled clays containing selenite in great quantity, and not 
unofrequently in large crystals. These clays have, on many 
occasions, unpleasantly reminded the Estate authorities of their 
existence, for the coherence of their particles is not strong, and 
frequent landslips have taken piace on slopes and banks, so that 
much expense has been incurred to guard against such slips in the 
numerous cuttings of the Estate railways. 


After I had examined the district near Ste. Madeleine, I had the 
advantage of the company of Mr. Guppy in my visit to the western 
portion of the area. We visited the quarries and road-cuttings 
in the upper parts of the marls on Philippine, Hermitage, and 
Cedar Grove Estates, and examined the numerous exposures in the 
roadside-trenches. In this part of the district the relationship of 
the Oceanic Beds to the lower strata is far less apparent than in the 
neighbourhood of Ste. Madeleine, but what I noticed served to 
confirm my earlier observations. The road from San Fernando to 
Hermitage gradually crosses the area of the Oceanic Beds at an 
angle to the strike, and thus their sequence can be made out. 

Mr. Guppy, before our visit, told me that he had reason to believe 
that the sequence from the Globigerina-beds to the radiolarian 
marls was continuous. This we were able to confirm; the 
calcareous buff and cream-coloured Globigerina-marls gradually 
and almost imperceptibly change into more calcareous, heavy, white, 
chalky beds, and from these into more and more siliceous beds, 
becoming lighter in density and in colour until they assume 
characters practically identical with those of the great mass of the 
calcareo-siliceous radiolarian earths of Barbados. 

The Oceanic Beds appeared, as a rule, to dip at comparatively low 
angles to the north, and to east and west of north, although in 


184 MESSRS. J. B. HARRISON & A. J. JUKES-BROWNE [May 1899; 


places, as at Cedar Grove and at Hermitage, the rocks dip at some- 
what high angles, this being apparently caused by local faulting. 


The Oceanic Series of Naparima differs greatly, in the relative 
development of its various members, from the typical series seen in 
Barbados. In the latter island the series is ushered in by white 
and greyish-white chalks, containing from 60 to over 80 per cent. 
of calcium carbonate, which in the course of about 20 to 30 feet 
pass through calcareo-siliceous beds into the siliceo-calcareous and 
siliceous earths forming the main mass of the deposit with a 
thickness of about 170 feet. I was not able to obtain any exact 
measurements in Trinidad, but the Globigerina-marl appeared to be 
approximately from 120 to 140 feet thick in the localities where I 
examined it; while the radiolarian beds did not appear to exceed 
40 or 50 feet in thickness. I did not observe any layers of volcanic 
ashes like those so frequently interbedded throughout the Barbados 
series, but Dr. Gregory has described a pumiceous earth from this 
district which was sent to him by Mr. Guppy.’ 

Samples were collected from the beds examined, and were analysed 
by the methods described in the paper on the geology of Barbados.” 
For comparison, the analyses of samples of the middle and higher 
beds, which were tabulated in the above-mentioned paper, are 
reproduced in the following table. The analyses recently made 
are numbered 1 to 3, those previously made being Nos. 4 to 6 :— 


Globigerina-beds.| Passage-beds. | Radiolarian beds. 
if 2 3 4, 5 6 
( Loss on ignition ...... 4-97 6-21 317 2°38 4-62 2-11 
| Calcium carbonate ...| 33°23 | 35°81 | 4883 | 4050 | 2946 | 31°82 
A { Calcium phosphate... 30 02 "28 ae trace | trace 
| Magnesium carbonate} 1:14 nt 119 ee et he 
\ Colloid silica, ......... 5°73 722, | 10-29 | 19°66. | 41:15) aia 
(Iron peroxide and 
DEM et Ses one c= Tal "28 1-23 5°64 ool 4°10 
| Manganese peroxide. . 32 trace trace “32 “44 "82 
BS bain He Seracech eatin case aa: 1:33 rr 1-22 Lad 1:50 
(MAE TESTE). foniceaw we. "05 “56 ‘04 2°34 ‘41 1:18 
CT Bip. toncaci eer 49°44 | 88°93 | 29°13 | 26°38 15°36 | 15°16 
| Alkalies and loss ...... trace ‘20 ‘29 trace trace trace 
Ge We marta ee. oe. ce 3°31 8:67 es) 1:38 4-05 1°47 
D. Calcium sulphate... .. ‘78 ai | 16 18 ‘09 “28 
100°04 |100:00 | 100-00 | 100-00 | 100:00 | 100-00 


[The bracket A includes the organic constituents, the bracket B the argil- 
laceous and earthy constituents, and D is regarded as an adherent salt. | 


? Quart. Journ. Geol. Soc. vol. xlviii (1892) p. 539. 
+ Ihid. p. 182. 


Vol. 55. | ON THE OCEANIC DEPOSITS OF TRINIDAD. 185 

For comparison with the foregoing analyses, it will be useful to 
state the average composition of the corresponding beds in Barbados ; 
this is as follows :-— 


Globigerina-| Passage- | Radiolarian 

chalks. beds. beds. 

(Loss on ignition ............ par glk 2°64 4-38 

| Calcium carbonate ......... 70-40 60°49 16°65 

A.4 Calcium phosphate ......... ‘OT ai 4 
| Magnesium carbsnate ....... it os 

MColloidyoilica: 2. .0..c600-2a0 062 10°52 18-05 46°70 

{ [ron peroxide and alumina 2°89 3°09 6°69 

| Manganese peroxide ......... 48 “93 18 

B 4 ATMEM Crater See e ene eseasnee (es 1:10 2°20 

Pa ESI Fi lenden de tan en's “02 “2 1-09 

| Clay and silicates ............ 10°28 11:80 19:31 

\ Alkalies and less ............ "22 “29 37 

OE ee re ‘26 “19 ‘95 

D. Calcium sulphate ............ 21 23 1-07 

100-00 100-00 100-00 


The resemblances and differences between the two series will be 
more apparent, if the two sets of analyses are summarized as 
follows :— 


Globigerina-beds.| Passage-beds. | Radiolarian beds. 
Trin. Barb. Wrest Barb Trin Barb. 
Organic constituents} 47°32 | 84-00 63°15 81°65 | 75°36 68:14 
Earthy constituents | 45°89 15°53 33°29 17-98 21°70 29°84 
PU GANEZ,  pmrosmno tens «= « 6:02 "26 3°39 "19 2°76 "95 
Adherent salts ...... 17 ‘21 “Lh ‘23 18 1:07 
10000 | 100:00 | 100-00 | 100:00 | 100-00 | 100-00 


From the foregoing table it is seen that considerable differences 
exist between the Oceanic deposits of Trinidad and Barbados, and 
this is more particularly the case with the lower members of the 
series. The higher proportions of quartz and of argillaceous matter 
in the Globigerina-marls of Trinidad point to their having been 
deposited rather nearer land than those of Barbados. The calcareo- 
siliceous beds show the same differences, but with regard to the 
purer radiolarian earths the case seems at first sight otherwise, 
for, though the proportion of quartz is higher in Trinidad, that 


186 MESSRS. J. B. HARRISON & A. J. JUKES-BROWNE [May 1899, 


entered as argillaceous matter is higher in Barbados. This, how- 
ever, is probably due to the larger quantity of pumiceous and 
volcanic dust present in the Barbadian earths. 

Mr. Guppy has described the Globigerina-marls of Naparima as 
containing from 80 to 90 per cent. of calcareous matter ;* but 1 am 
inclined to view this estimate with some distrust, for he afterwards 
states that, upon washing, about half the material passes off as fine 
mud, and that half of the remainder consists of indeterminable and 


Fig. 2.—Comparison of the rock-succession in Trinidad 
and Barbados. 


BARBADOS. 


\ 


Volcanic mudstones. 


ay Upp <7 me 
fe ier Yin 
ee 
> <7 
FS 


MGM 
eee ya Red clays. 
eee Yi, 
UTTER 
=r : 
To ln Upper chalks. - 


TRINIDAD. 


Calcareo-siliceous 


Top not seen beds. 


Radioiarian earths. 


os SS Se 


Passage-beds ......... S525 


Pure radiolarian 


earths. 
Globigerina-marls ... 
ee SSS] Calcareous earths 
ie T ae and Chalks. 


—<————— 
1 


Se 


(eae 


WNariva Series .......-- Scotland Beds. 


[Scale: 100 feet = 1 inch. ] 


amorphous particles, bits of pumice, iron-pyrites, etc. I question 
whether any of the Trinidad Globigerina-marls contain as much as 
60 per cent. of calcareous matter. 

In describing the radiolarian marls, he mentions that half of 
the rock is made up of ‘small scales and lumps of a pearly grey 
colour and iridescent surface.’* In the specimen examined by me 
these are present to a certain extent, but do not form more than 


1 Quart. Journ. Geol. Soc. vol. xlviii (1892) p. 528. 2 Ibid. loc. cit. 


Vole 55.] ON THE OCEANIC DEPOSITS OF TRINIDAD. 187 


20 per cent. of the rock. Similar iridescent scales occur in many 
of the Barbadian earths, but in smaller quantity. When examined 
with a high power (2 inch) under the microscope, they are seen to 
be fragments of the frustules of a diatom, the iridescence being 
caused by the minute delicate markings of its valves. The frag- 
ments appear to have belonged to the genus Hthmodiscus, which, 
according to Sir John Murray, is ‘ quite characteristic of some of the 
deepest tropical red clays and radiolarian oozes far from land.’ ' 


The results of the observations madé in the field, and of the 
analyses made in the laboratory, combine to show that there is a 
succession of Oceanic deposits in Trinidad comparable in all respects 
with that which is found in Barbados. In both islands there is an 
upward gradation from calcareous marls or chalks, through caleareo- 
siliceous beds, to purely siliceous material made up of the tests and 
frustules of radiolaria and diatoms. 

In Trinidad, however, there is a much greater development of 
the calcareous deposit than in Barbados, while the radiolarian beds 
are not so thick. ‘These differences are brought out more clearly 
by the accompanying comparison of the rock-succession in the two 
islands (fig. 2). Such differences are what might be expected if, as 
already suggested, one series was accumulated nearer to continental 
land than the other; but both are such deposits as are now found in 
ocean-depths at some distance from land, and the quartz which they 
contain is in so fine a state of division, and in such small quantity, 
that its existence is disclosed only by chemical analysis. 


I was not able to make a detailed examination of the so-called 
argiline-beds of the hill near San Fernando, but I had previously 
visited the quarries, and from observations on the spot, and from 
examination of slices cut from the rocks of the hill, I incline to 
believe that the argiline has been formed by the alteration of 
the lower Globigerina-marls. Under favourable circumstances, per- 
colating water might remove all the calcareous matter, leaving ouly 
the clay and siliceous material; subsequently some of the silica 
may have been dissolved and redeposited as a siliceous cement. 
1 agree with Mr. Guppy in regarding the argiline as originally 
a deep-water deposit similar to the Naparima Marls; but I can see 
no reason for looking upon it as of earlier date, or as belonging to 
a different formation. In all probability it is part of the same 
series, only in an altered condition. 


There remain for consideration the Nariva Series and its re- 
lation to those beds near San Fernando which have yielded an 
Kocene or Oligocene fauna, and for which the name San Fernando 
Beds may conveniently be retained. My opinion that the Nariva 
Clays of the inland area underlie the Naparima (Oceanic) Marls 


* Challenger Rep. 1891, ‘Deep-sea Deposits,’ p. 31. [It appears, however, 
that this form has been found in the Arafura Sea and other localities not very 
far from land; see the discussion on this paper, p. 189.} 


185 MESSRS. J. B. HARRISON & A. J, JUKES-BROWNE [May 1899, 


has already been expressed. Now, although no conclusion can be 
drawn from the juxtaposition of the beds seen in the cliff-section, 
yet the road above it passes in places through Globigerina-marls, 
suggesting the idea that patches of such marl overlie the San 
Fernando Beds unconformably. Moreover, Mr. Guppy’s description 
of what is presumably the lowest part of the San Fernando Beds, 
namely, his group 3, would apply equally to the Nariva Beds of 
the inland valleys. 

Seeing, therefore, that both the Nariva Series and the San 
Fernando Beds are shallow-water deposits of like character, and 
that they appear to occupy the same position with respect to the 
Oceanic Series, there is a reasonable presumption that they are 
closely connected in age, and form parts of one continuous series of 
beds. Thus, if the San Fernando Beds are of Oligocene age, it is 
possible that the Nariva Beds are of Eocene date. As to the beds 
exposed in the cliffs near Taruba Creek, I have not seen them and can 
express no opinion. If they are faulted down, as represented by 
Mr. Guppy, their age can only be guessed at from their resemblances 
to some one of the other formations. 

Regarded in combination, the Nariva-Fernando Series offers many 
points of resemblance to the Scotland Beds of Barbados, not only in 
lithological characters, but in fossil contents. Now, just as the 
Nucula-beds are apparently the highest part of the Trinidad Series, 
so also the fossils from which the Oligocene age of the Scotland 
Beds has been inferred all come from beds which are relatively high 
in the series. Hence, it is quite possible that the lower portions of 
the Scotland Beds are of Eocene age. 

In conclusion, I venture to propose the following correlation of 
the several rock-groups which have been discussed :— 


BARBADOS. TRINIDAD. 
Coral-rocks. Riomeniceees Pleistocene & 
Bissex Beds. ES : Pliocene. 
Oceanic Beds. Naparima Marls. Miocene. 


Scotland Beds, J Upper: | San Fernando Beds. Oligocene & 
Lower. | Nariva Series. Eocene. 


Discussion. 


Dr. Grreory expressed his pleasure at hearing the Secretary say 
that the paper was long, as a detailed account of these Trinidad 
oozes would be most useful. He had described samples of the 
three principal members of the deep-sea series in an appendix to 
Mr. Guppy’s last paper, and was glad to find the results confirmed. 
In the discussion on that paper he had objected to the reference of 
the oozes to the Eocene or Oligocene, and of any part of the series 
to the Cretaceous. He thought that the correlation adopted in the 
present paper would meet with universal approval. As coccospheres 
had been found by Mr. G. Murray, on the recent expedition of the 


Vok. 55-1] ON THE OCEANIC DEPOSITS OF TRINIDAD. 189 


Oceana, living in the Thames estuary in 8 fathoms of muddy water, 
conditions not precisely pelagic, he thought that the occurrence of 
Ethmodiscus was hardly sufficient to prove that the Trinidad deposits 
were formed far from land, in face of opposite geological evidence. 

Prof. Sortas remarked that, in a previous paper read before the 
Society on the Barbadian deposits, the Authors had presented 
convincing testimony as to the deep-sea conditions under which those 
deposits were formed. In the present communication the argument 
was not strengthened by the citation of Hthmodiscus. Out of a total of 
15 species described by Count Castracane in the Challenger Report, 
five were from the Arafura Sea, neither deep nor far from land, and 
one from the Antarctic Ocean, at a depth of only 350 fathoms. 
These diatoms, like others, were surface-organisms, and it was 
difficult to understand how the depth of the sea could determine the 
nature of the genera which inhabited its upper layers. 

Dr. G. J. Hype and Prof. Warts also spoke. 


t 
Btn ees 


190 JOSEPH THOMSON ON THE GEOLOGY OF [May 1899, 


11. The Guotocy of SournerN Morocco and the Attas Mountatns. 
By the late Josspu Tomson, Esq. (Communicated by the 
Presipent. Read January 18th, 1899.) 


ConTENTS. Page 

1s Introductory, Reniatks i.:5..1c.5eceehe eae eee nee eee 190 
II. Geographical Sketch of Southern Morocco and the Atlas...... 191 
TED. The Coastal Wowlands'" :2-.-.0-.0cn-2:"-tecse teat ee eee een 194 
IV: Phe Platead vA Mek a 196 
V. The Attias ‘Mountains 4.2222 ss¢iat de ckevins Sod. ee cee ee 198 


(1) The Wad Demnat. 

(2) The Wad Gadat. 

(3) The Mountains in Glauwa and Misfiwa. 
(4) The Wad Urika. 

(5) The Wad Reraya. 

(6) From Amsmiz across Gindafy to Sus. 
(7) The Asif el Mel. 

(8) From Imintanut to Sus. 


I. Inrropuctory REMARKS. 


Among the curious facts of the 19th century there are few things 
more notable than our comparative ignorance of the geography and 
geology of the Empire of Morocco. Here is an extensive country 
within sight of Europe, and even within sound of the guns of a 
British garrison-town, about which we in many respects know less 
than about many districts in the remotest depths of the African Con- 
tinent. Within recent years something has been done to dispel our 
ignorance of the geography of Morocco, but geologically our knowledge 
of it remains almost at a standstill. 

Previous to the expedition of Sir Joseph Hooker to the Great 
Atlas in 1871, hardly a single ray of light had been thrown upon 
the stratigraphical constitution of Southern Morocco, and since that 
time barely one trustworthy fact has been added to the sum total. 
Practically the geological literature of Southern Morocco consists of 
a paper by Mr. Maw, who accompanied Sir Joseph, entitled ‘ Notes 
on the Geology of the Plain of Marocco & the Great Atlas,’ and 
published as an appendix to Hooker & Bali’s ‘Tour in Marocco & 
the Great Atlas.’ * | 

In the beginning of 1888 I conceived the idea of attempting the 
exploration of the less known parts of the Moorish Empire, and 
especially of the Atlas Mountains. In pursuit of this enterprise I 
left England on March 9th, returning home towards the end of 
October, successful beyond my expectations so far as the Atlas 
and Southern Morocco are concerned. I was enabled to cross the 
range in several new directions, and ascend heights never before 
achieved, with the result that a clearer and more accurate notion of 
the geography of the Atlas has been secured. 

But while geographical exploration was my special object, and 
largely absorbed my attention and time, I was not unmindful of 
the claims of geology, nor forgetful of its intimate connexion with 
geography. In venturing now to bring together my geological 


1 [London, 1878. Appendix H, pp. 446-467, with 6 figs. in the text, & 
horiz. sect. | 


Vol. 55.] SOUTHERN MOROCCO AND THE ATLAS MOUNTAINS. 191 


gleanings in the form of a paper, it is necessary to remember two 
things: first, that I do not write with the authority of a geologist, 
but only as a geographical explorer with a certain amount of geo- 
logical training. Equally important is it to remember that the 
conditions of travel in Morocco are not such as will permit of any- 
thing but the most cursory examination of the strata which may 
crop up before the traveller. I very cordially agree with Sir 
Joseph Hooker’s conclusion that Morocco is the most difficult of all 
countries in which to travel with advantage, so soon as the great 
highways are left behind. The traveller is looked upon as a spy 
examining the riches of the country. Hverything that he does is 
seen through the medium of this belief, and twisted accordingly. 
His servants and escort are not only spies, but obstructionists of the 
most maddening type. It is sufficient to be seen doing or collecting 
something that the natives do not understand, to be turned back 
at an important point or plunged into a world of trouble. That 
traveller has the most chance of going farthest who appears to do 
and see least, and who seldom ventures from the beaten track. 

Of all scientific pursuits in that country, botanizing is the least 
dangerous, for the Moors have the greatest faith in the medicinal 
virtues of plants and interpret the collector’s movements accordingly. 
With geologizing, however, it is far different. To be seen examining 
rocks, chipping off specimens, or picking up pebbles is sufficient to 
raise a frightful hue and cry throughout a whole neighbourhood. 
Such proceedings can bear but one interpretation—that the Christian 
is seeking for valuable minerals, which the natives firmly believe 
abound everywhere, and that the discovery of such mineral wealth 
will only tempt the Europeans to seize their country. 

Under any circumstances this restriction would be bad enough, 
but it was doubly so in my own case, as I had to force my way into 
the Atlas Mountains in face of the express prohibition of the 
Government, and in spite of unwilling servants who did all in their 
power to thwart me, and were ever ready to turn the slightest 
action on my part as a weapon against me. My own men formed 
my greatest danger and obstruction, and more than once, when 
success in some feat or other seemed assured, I was defeated by 
their treacherous underhand plots and misrepresentations. The 
following notes then, be it understood, are almost entirely gleaned 
by passing glances from the pathway, unaided by careful examina- 
tion or gathered specimens for after-study. Hence their sketchiness, 
and, if they can claim to have any value at all, it is because the 
Atlas Mountains form virgin ground to the geologist, where he 
could fail to note something new only by absolutely shutting his 
eyes to everything around him. 


Il. GroGRAPHICAL SKETCH OF SOUTHERN Morocco AnD THE ATLAS. 


The country to which the following notes apply is that tri- 
angular part of Southern Morocco * whose base is the Atlantic Ocean, 


1 |Most, if not all, of the localities mentioned in the present paper will be 
found in tue author’s map of South-western Morocco, Proc, Roy. Geogr. Soc. 


192 JOSEPH THOMSON ON THE GEOLOGY OF [May 1899, 


between Saffi in the north and Agadir in the south, the apex being 
the district of Demnat, on the northern slopes of the Atlas Moun- 
tains, and some 60 miles east of the city of Morocco. 

Regarded geographically, this area may be described as consisting 
of three sections :—(1) A comparatively small tract of coastal low- 
lands rising to a height of 700 feet, and forming the province of Abda. 
(2) A larger area of plateau-land occupying the greater portion of 
the triangle and consisting of two platforms, the northern rising in 
altitude from 1000 to 2000 feet, forming the provinces of Bled 
Hummel, Shiedma, Rahamna, and the minor Kaidships into which 
the plain of Morocco is divided; while the southern platform 
consists of more irregular highlands, ranging from 3500 to nearly 
5000 feet above sea-level, and comprising the important provinces 
of Haha and Mtuga. (38) The third great feature in this part of 
Southern Morocco is the Atlas itself. Formerly this magnificent 
range of mountains was described as beginning at the coast, but 
as the result of my observations I have come to the conclusion that 
geologically and geographically it commences in reality as a range 
nearly 30 miles inland, where the glen of the Asif Ig forms a sharp 
line of demarcation between the plateau and the mountain-chain. 

Assuming, then, that the Atlas range commences at the Asif Ig, 
we find that it trends east by north, rapidly rising to heights 
varying between 8000 and 10,000 feet, and forming a massive range 
which towers up from a broad pediment 2000 to 4000 feet lower. 
Farther east, or some 60 miles from its western end, the range 
attains a general altitude of nearly 11,500 feet, the highest summit 
at this part being Jebel Ogdimt, which I ascended and found to be 
more than 12,700 feet high. 

From Jebel Ogdimt eastward for a distance of 60 miles, the 
Atlas displays its highest summits, reaching an altitude which 
I estimated at 14,500 feet, in the culminating mass of the 
Tizi-n-Tamjurt. At the Tizi Likumpt, on its eastern shoulder, I 
reached a height of 13,150 feet, and was therefore in a position to 
form an approximate estimate of the height of the Tizi-n-Tamjurt. 
Along this central part of the range, the trend of the main axis is north- 
easterly, a direction which it maintains for a considerable distance. 

Though thus attaining exceptionally high altitudes, the Atlas 
exhibits scarcely any conspicuous peaks or mountain-masses. Now 
and again, a part of the range seems to promise such a feature, but 
in almost every case an alteration of the point of view shows it to 
be more illusory than real. Seen from the city of Morocco, the 
only peaks that can be easily identified are Jebel Erduz, Jebel 
Tezah, Jebel Sig—the Miltsin of Adm. Washington '—and Jebel 
Glauwa; and even these, as compared with the general altitude and 
imposing mass of the range, are but small protuberances. 

On the whole, the general appearance of the Atlas is disappointing, 


vol. xi (1889), facing p. 64. Views of the mountain and glen scenery, repro- 
duced from the author’s photographs, appear in his popular account of 
g Travels | in the Atlas & Southern Morocco,’ London, 1889.— Ep]. 

' (‘Geographical Notice of the Apis of Marocco,’ Journ. Roy. Geogr. Soe. 
vol, i (1832) p. 140.] 


Vol. 55.] SOUTHERN MOROCCO AND THE ATLAS MOUNTAINS. 193 


especially when near at hand. It is too uniform in height, too 
little broken in outline, and it rises to its culminating crest by too 
many steps, to produce that effect on the observer’s mind which one 
naturally associates with mountain-masses rising to an altitude of 
13,000 feet. Only in early spring, when partially covered with 
snow, and when seen at a distance of 50 or 60 miles, does it 
present a really picturesque and imposing appearance, for then the 
lower steps are blended into the one great range and it looks the 
magnificent mass that it really is; while the snow brings into relief 
such prominences as there are, and shows up the glens and depres- 
sions with picturesque effect. 

With mountains of such height and extent one naturally expects 
to find numerous rivers draining their rain and snowfall to the 
plains: these, of course, are not wanting. From near Demnat to 
Mtuga, at the western end of the range, the northern slopes are 
drained by the various tributaries of the Wads Tensift and Um-er- 
Rebia. Of the latter, the most important affluents in the district 
of which I speak are the Demnat and the Tessaout, neither of which 
penetrates quite into the heart of the range, though draining right 
up to the base of the central crest. 

It is different with the chief tributaries of the Tensift. Taking 
them in their order from east to west, the first is the Wad Gadat, 
which not only penetrates all the lower range but nearly cuts across 
the centre of the chain, thus forming the Tizi-n-Teluet or Pass to 
Teluet, and the basin of the Wad Draa. . 

A few miles west of the Gadat flows the Wad Misfiwa, which 
cuts less deeply into the central mass. A little farther west again 
comes the Wad Urika, which after penetrating right into the heart 
of the main chain splits into two: one branch gathering its waters 
from the Jebel Asif Sig, and forming a pass to the southern slopes, 
while the other branch, turning westward, has carved for itself a deep 
impassable glen along the central crest, which it thus cuts in two 
for a distance of nearly 30 miles. The next important stream that 
one meets is the Wad Reraya, which, after cutting through the 
lowest of the outer Atlas steps, separates into two branches, both 
of which reach the central crest without cutting much into it. 
Most important of all, however, is the Wad Nyfis, which, after 
penetrating into the very heart of the range, divides into two, the 
larger branch (as in the case of the Urika) turning westward and 
draining a great glen called Gindafy, which it has excavated for 
itself right up to Jebel Ogdimt, thus slicing longitudinally the back- 
bone of the chain. The other branch, the Wad Agandice, has cut 
for itself a veritable canon through the southern section of the 
divided crest, and practically gathers its waters from the southern 
slopes. Still going westward, the Asif el Mel is the only stream of 
any size which penetrates to the base of the main range, and then 
divides. The Wad Imintanut, though but a small stream, is of 
importance as the excavator of a glen through the outer slopes, 
along which runs the chief road from Morocco proper to Sus. This 
glen, with the Wad Ida Uziki and the Asif Ig, serves to mark off 
the western extension of the Atlasrange. With the single exception 


Q.J.G.8. No. 218. 0 


194 JOSEPH THOMSON ON THE GEOLOGY OF [May 1899, 


of the Wad Misfiwa, I penetrated the glens of the streams described, 
and was thus able, thanks to the sections displayed in their precipices 
and bare rocky slopes, to form a very fair idea of the internal 
structure and constitution of the range, despite the difficulties which 
beset me on every hand. 

As regards the southern slopes, I need say but little: from Agadir 
to the borders of the province of Glauwa the Wad Sus collects all the 
drainage, while farther east the Draa performs that function. 

In possession of these general notions regarding the geography of 
Southern Morocco and its great mountain-chain, one may now more 
intelligibly proceed to consider the internal structure of the region. 


Iii. Tae Coastat Lowianns. 


Commencing this survey with the coastal lowlands, I may re- 
mark that they are practically conterminous with the Tertiary 
deposits, which here attain a very considerable development. 

At Casablanea they form a vast plain, but little raised above the 
level of the sea, and consisting of grey and puce-coloured shales, 
which probably, judging from lithological resemblances, belong to 
the same series as the Cretaceous rocks around Tangier. 

Travelling southward, the country rapidly rises to a height of 
100 or more feet, and stretches out in undulating treeless monotony. 
Here one remarks flaggy sandstone, which farther on disappears. 
At Azimur the cliff-sections of the Um-er-Rebia show a series of 
reddish friable rocks and porous conglomerate, with shell-rock at 
the top. The lower of these have been regarded as HKocene, and 
the upper as Miocene—from the occurrence of Teredina personata 
in the one, and Balanus sulcatus, Pecten Beudanti, Arca, Buccinum 
prismaticum, and Conus in the other." 

From Mazagan to the south of Azimur my route led inland 
through the provinces of Dukalla and Abda, and as there were 
neither watercourses nor cliffs it was impossible to form any idea 
of the geology, except of such rocks as cropped out at the surface. 

Nothing more was to be seen of the flaggy sandstones and shales 
of Cretaceous age, or of the conglomerates. and marls noted at 
Azimur. The whole country appeared to be covered to a consider- 
able depth with a compact shell-sand, full of fragments of Pecten 
and Conus, all belonging, I judge, to Pliocene times. These deposits 
are found at an ever-increasing elevation as one goes southward— 
occurring as high as 700 feet above sea-level to the east of Safi. 
This is undoubtedly due to their inclusion within the area affected 
by the upheaval of the Atlas—the district nearest the focus of 
elevation having undergone the greatest upheaval. 

In travelling over these Tertiary lowlands it becomes very clear 
to the explorer that the surface-features of the country are not such 
as would result from subaerial denudation. On all sides, one sees 
curious hummocky mounds and ridges with no determinate or general 
trend, as well as cup-shaped and irregular hollows, which could 


1 [Maw, App. H to Hooker & Ball’s ‘Marocco & the Great Atlas’ (1878) 
p. 453. ] 


Vol. 55.] | SOUrHERN MOROCCO AND THE ATLAS MOUNTAINS. 195 


in no wise be formed by the ordinary action of surface-streams. 
These lowland areas, in fact, represent a Tertiary sea-bottom, 
raised above the water exactly as it was formed. It might have 
been supposed that all its characteristic features would have been 
obliterated during the long ages which have elapsed between its 
first appearance above water and the present day. The survival of 
these features, without a doubt, is due to the porous character of the 
shell-sands, permitting the absorption of the rainfall, and preventing 
the formation of streams and rivulets. Over large districts, however, 


the subaerial denudation of the country has been prevented in a 


totally different manner—namely, by the formation of a slag-like 
calcareous crust of extreme hardness, which practically seals up 
the ground and defies equally the operations of the husbandman 
and the weathering agencies of nature. 

The natives take advantage of the occurrence of this slaggy crust 
over an easily-excavated rock to dig their underground granaries 
and reservoirs. Its origin is ascribed by Maw,’ and I believe 
correctly, to the rapid evaporation of waters charged with soluble 
carbonate of lime by the intense heat of the sun. ‘The residual 
arbonate is deposited layer by layer on the surface. He speaks 
of it forming accumulations in this manner several feet thick; but 
on that point I am disposed to think that he must be mistaken, 
and that he has confounded the surface-soil and upper layers of 
rock cemented into a more compact mass by the precipitated car- 
bonate with the actual deposit of calcareous crust itself. In any 
case, I have never seen any such deposit thicker than a couple of 
inches, while I have frequently observed the surface-layers of a 
porous rock as well as sand cemented by the deposition of new 
matter into a marble-like compactness. 

It would be difficult to say what thickness these Tertiary shell- 
sands reach, but itis probably in places 200 or 300 feet. At one 
locality, south of Saffi, our Vice-Consul, Mr. Hunot, sank a well 
for a depth of more than 100 feet, before reaching a white 
lithographic stone; and a section exceeding 200 feet in thickness 
is shown at the Jews’ Cliff, a few miles south of Saffi. At the 
last-named locality, Miocene beds are seen cropping out from beneath 
others of Pliocene date, and dipping at a considerable angle north- 
westward. Underneath, at the base of the cliff, are Cretaceous red 
and grey marls, and a white sandstone. 

Among the most interesting phenomena, however, observable 
in the Tertiary deposits near Saffi are several quarry-like holes in 
the shell-rock. One of these may be found close to Mr. Hunot’s 
farm, and another immediately behind the Jews’ Cliff. At a 
cursory glance, one would naturally assume them to be what they 
seem, namely, quarries, until a more careful examination shows that 
the rock is not such as is used for building, and that if they have 
been used as quarries they have been worked in a very unusual 
and peculiar manner. 

On the other hand, the inhabitants themselves look upon these 


D (Op: cit. pe 450. 


02 


196 JOSEPH THOMSON ON THE GEOLOGY OF [May 1899,. 


holes as something beyond their knowledge. The cayity near 
Mr. Hunot’s farm is a circular pit, 30 or 40 feet in diameter and 
from 20 to 30 feet deep. On one side rises a pillar of pure white 
calcium carbonate, strangely unlike the reddish-yellow shell-rock 
which surrounds it. This white carbonate spreads out, mushroom-- 
like, at the top, and forms a considerable deposit on the surface. 

The only theory by which I can account for this curious pit, 
with its white pillar, is that at one time a hot spring, charged 
with carbonate of lime, rose to the surface where now stands the 
pillar, depositing its calcareous burden at its mouth. In time, the: 
pipe by which it found its way to the open air became choked by 
encrustations of carbonate of lime, and then an explosion of steam 
drilled a broader passage through the superincumbent rock, forming” 
the quarry-like cavity that now exists. ‘The formation of the other 
cavities may be reasonably ascribed to a similar cause. 


IV. THe Puareav. 


On quitting the lowlands for the plateau the traveller practically 
leaves behind the Tertiary area, and enters upon a region charac- 
terized by metamorphic rocks and Cretaceous grey “and eream- 
coloured limestones, red sandstones, and red and purple clays. I 
am aware that Maw suggests the possibility that some of the strata 
in the plain of Morocco and on the flanks of the Atlas may yet 
prove to be of Miocene age, but this supposition appears to me to 
be founded on insufficient evidence. Certainly, as yet, no paleon-- 
tological data have been brought forward to support this idea, and 
the lithological evidence is of the most slender nature. In my 
own opinion, the whole of the plateau of Southern Morocco has 
been above water since the earliest Tertiary times. 


The metamorphic rocks cover the whole of Rahamna and 
most of the great plain of Morocco, formed by the various tribu- 
taries of the Tensift descending from the Atlas. In Rahamna and 
Srarna they attain a considerable development; forming a very 
broken and irregular series of mountains, termed Jebelet or Little 
Mountain—-the Atlas being the Jebel or Mountain proper. 

The Jebelet consists of much smashed and contorted clay-slates, 
mostly lying vertical, with a general north-north-east and south- 
south-westerly strike. These rocks, owing to their friability and 
to the ease with which they split up, owing also to the prevalence 
of more compact bosses and veins, form an extremely chaotic com- 
plex of barren peaks and jagged ridges, having a general trend 
parallel with the strike. Possibly these metamorphic mountains 
represent the western, outcropping ends of a great syncline of 
clay-slates, the plain of Morocco occupying tke hollow; while the 
opposite or eastern end forms the core of the central axis of the 
Atlas itself. The southern limit of outcrop is not yet ascertained,,. 
but the series is seen close to Amsmiz, and thence it probably 
runs north-westward or north-north-westward to the Wad Tensift. 


Vol. 55.] SOUTHERN MOROCCO AND THE ATLAS MOUNTAINS. 197 


The rest of the plateau is entirely occupied by the Cretaceous 
rocks, which may be divided into two groups: (1) the Lower, or 
red shales and sandstones ; and (2) the Upper, or grey and cream- 
coloured limestones. 

(1) The red shales and sandstones are chiefly exposed, 
owing to the comparative absence of the Upper beds, in the pro- 
vince of Bled Hummel, which has received its name of Hummel, or 
Red, from the prevalent colour of the strata and soil. 

Passing eastward from Saffi over the Tertiary shell-sands of 
Abda, the red shales are seen to rise in an abrupt escarpment several 
hundred feet high, having a capping of white limestone of no 
great thickness, and continue thence to the metamorphic area of 
Rahamna. South of the Wad Tensift the Lower Cretaceous rocks 
are almost entirely masked by the limestone, except where dis- 
turbances of the strata have brought them to the surface. Such 
disturbances have taken place at Jebel Hadid, south of the Wad 
Tensift, and at the Ida Issa Mountains, south of Mogador; but 
elsewhere they are little seen. 

There is one feature of these red shales which is worth noting, 
namely, the prevalence of salt-springs. Wherever the shales are 
found, there also brine-springs occur. In Bled Hummel the brine- - 
springs are so abundant as to give rise to the small saliferous lake 
of Zima, whence in the summer a considerable quantity of salt is 
obtained by evaporation from the shallows and backwaters. Close 
to Jebel Hadid are brine-springs, which are led into shallow pans, 
where the water is evaporated. Among the shales of the Ida Issa 
Mountains similar springs are found. Leaving, for a moment, 
the plateau for the Atlas, one notes the same occurrence. At 
Demnat, not only brine-springs, but extensive salt-deposits occur. 
In the basin of the Wad Gadat there is a salt-stream; at Asni in 
Reraya brine-springs well out, which supply all that section of the 
range with salt. Other localities might be mentioned where brine- 
springs are associated with the red shales, but these will suffice for 
our purpose. | 


(2) The Upper Cretaceous or Limestone group of Southern 
Morocco attains an enormous development. Setting aside the 
Atlas, these rocks are found rising to a height of over 5000 feet 
above sea-level; they are largely composed of limestones with white 
marls and shales, and at places yellowish sandstones—the whole 
resting on the red and purple shales and sandstones. 

Considered as a whole, they seem to have been but slightly dis- 
turbed, despite their elevation to the extent mentioned, which would 
seem to show that they were raised by some gradual movement, 
rather than by any violent and sudden action. As might be expected, 
however, there is more evidence of violent disturbance of the strata 
as one approaches the principal focus of upheaval—that is, the line 
along which the Atlas range has been squeezed or ridged up to its 
present position. There can, of course, be no doubt that the forces 


198 JOSEPH THOMSON ON THE GEOLOGY OF [May 1899, 


which produced the mountain-chain are the same as those which 
formed the plateau. 

Allusion has already been made to two districts where local 
disturbances of the strata have occurred. Of these, the most 
interesting is Jebel Hadid, or Iron Mountain. Here the massive 
compact limestones are thrust up from their horizontal position, till 
they stand on end, forming a narrow range nearly 20 miles long, 
recalling in its jagged skyline the dorsal fin of a fish. The internal. 
force, however, which was sufficient to form a mountain-range 
2500 feet high was not expended in the effort, and assumed a 
volcanic character in drilling a way for itself through the heart of 
the mountains, forming a huge pit, now nearly filled with the fallen 
debris. Springs, probably hot and charged with hydrated oxides 
of iron, succeeded what was doubtless a primary explosion of steam, 
and deposited their mineral burden among the shattered rocks and 
volcanic ejectamenta. In process of time, these springs either dried 
up or found exits in other parts of the district; and within the 
historic period the natives of the country have found it worth their 
while to extract the ore left behind in the famous iron-mines, which: 
have been worked from time immemorial, though totally disused at 
the present day. It is not improbable that there is some connexion 
between the Hadid disturbance and the curious pits in the Tertiary 
rocks near Saffi (see p. 195), as also the hot springs on the Kaib, 
close to Mogador: they are all situated along the same line. 

Over the greater part of this Cretaceous area no fossils are found. 
This is specially the case in the province of Shiedma and the greater 

art of Haha. In Mtuga, however, and in the mountainous district 
of the Ida-Utanein, fossiliferous beds are numerous and will certainly 
yield a valuable harvest to the paleontologist who can devote some 
time to their examination. Unfortunately I myself was unable to 
do much collecting, as I was in a manner flying for my life when 
I crossed the fossiliferous district and dared not increase the danger 
which we ran, by wasting time or adding to our impedimenta. The 
few fossils that I was able to pick up, however, included charac- 
teristic Cretaceous forms. 


V. Tue Arias Mountains. 


Turning now to the Atlas Mountains, the third section into which 
I have divided Southern Morocco, it should be clearly understood 
that, in speaking generally of the Atlas, include simply that section 
of the range which came under my own observation : namely, from 
Demnat to the western end. 

Stated briefly, the Atlas exhibits an approximate repetition of the 
geology of the plateau. There is, first, a core or backbone of meta- 
morphic rock, more or less disturbed by the intrusion of diorite, 
porphyrite, and other igneous rocks, and rising to the highest 
elevation of the range. Secondly, there is an enormous development 
of the Lower Cretaceous Series, flanking the metamorphic rocks om 


Vol. 55.] SOUTHERN MOROCCO AND THE ATLAS MOUNTAINS, 199 


both sides of the range, and, north of Jebel Glauwa, completely 
masking them. This series may be found at a height of over 
11,000 feet above sea-level on either side of the Tizi-n-Teluet. 
Thirdly, there is a less conspicuous development of the Limestone 
Series, flanking only the outer and lower elevations of the range, and 
probably never rising to a greater elevation than 5500 feet. This 
series (In the mountains) is characterized by the numerous basalt- 
dykes which break through it, with a general trend parallel to the 
main axis of the chain. In the fourth place, though no clear proof 
is forthcoming that any of the coastal Tertiary rocks are repre- 
sented, there is undoubted evidence of a Glacial period in the later 
history of the mountains, in the shape of moraine-heaps and ice- 
worn rocks and boulders in their glens and valleys. 

Where so little is known, every observation has a certain value ; 
and therefore, instead of considering each formation separately, I 
think that the best plan will be to act as guide to each glen, and take 
such note of the section exposed therein as the circumstances of 
the case will permit. The diagrammatic sections which | have 
prepared (figs. 1-6) will aid in the elucidation of my remarks. 

I propose to commence at Demnat, taking the glens in their 
order westward :— 


(1) The Wad Demnat. (Fig. 1, p. 200.) 


The Wad Demnat leaves the Atlas Mountains near the eastern 
termination of the great plain of Morocco. The entrance to the glen 
is through an open gorge cut out of a series of vertical limestones 
with intercalated beds of shale. The glen speedily begins to open 
out, the widening being due to a great dyke or boss of easily 
weathered basalt, the cccurrence of which provides a clue to the 
origin of the vertical position of the limestones and the unusual 
fertility of the soil, The town of Demnat stands in the hollow 
formed by the denudation of the basalt, the limestone-rocks sur- 
rounding it in an irregular amphitheatre of mountains and hills. 
Proceeding up the beautiful, fertile, terraced valley, the mountains 
close in, as the traveller passes once more from the basalt to the 
compact Limestone Series. This is not, however, thrust up verti- 
cally, but dips south or towards the mountains at an angle of 
some 30°. From this point the sides of the glen rapidly close in 
till, about 3 miles south of the town, they meet, seemingly blocking 
the valley by a precipice between 150 and 200 feet high, from the 
top of which the mountains again spring to a further height of 
500 to 1000 feet. 

At first the Wad Demnat appears to well from the living rock at 
the base of the limestones, but further observation reveals the 
existence of a narrow, broken gorge, arched over by a natural 
bridge of travertine, which joins the walls of the gorge at an 
altitude of over 1U0 feet. More remarkable still, it soon appears 
that this natural bridge fulfils the function of an aqueduct, by 
which a considerable stream is conveyed from one side of the glen 


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Vol. 55.] GEOLOGY OF SOUTHERN MOROCCO AND THE ATLAS, 201 


to the other, where it escapes in a waterfall, while it also forms an 
invaluable means of communication for the inhabitants of the 
opposing slopes. 

Above Iminifiri, as this singular natural bridge is called, the 
limestones are seen to form a comparatively shallow valley or 
mountain-step, broken somewhat by a series of ridges which are 
seen to coincide with synclines, off which the red shales and 
sandstones that occupy the hollows have been denuded. 

Beyond this middle section of the course of the Wad Demnat, the 
Irghalnsor mountain towers abruptly to a height of 5500 feet, its 
steep face coinciding with the northerly dip of the limestones. 
Between Irghalnsor and the main mass of the mountains lies the 
deep glen of the upper course of the Wad Demnat, carved out of 
the friable red shales and sandstones. 

Standing on this coign of vantage, it is not difficult for the observer 
to perceive that the massive, almost unbroken wall, which rises so 
majestically before him to a height of 10,000 feet, forming the 
central crest of the Atlas, is composed of sedimentary rocks similar 
to those upon which he stands, a conclusion verified farther west 
when the mountains are crossed from north to south. 

An excursion farther west, to Tasemset, and the excavations of 
the Wad Tessaout reveal a similar succession: the outer flanking 
limestones, in vertical or highly contorted beds, folded into V’s 
and W’s; an enormous basalt-dyke parallel with the axis of the 
mountains ; and a middle zone of limestones and shales, rising in 
broken scarped folds in ever-increasing magnitude, till they sweep 
skyward in one grand culminating mass. 

It is along this section that the Upper Cretaceous rocks attain 
their greatest development, masking indeed, so far as the secondary 
ranges are concerned, the lower shales and sandstones. 


(2) The Wad Gadat. (Fig. 2, p. 200.) 


We may pass now to the section which, following the Wad Gadat, 
crosses to the valley of Teluet, on the southern flank of the range. 
Starting from Tezert, about 4 miles east of the Gadat, the traveller’s 
route takes him over some low hills chiefly made up of friable basalt, 
which possibly may be a continuation of the Demnat dyke, occupying 
as it does the same position at the base of the mountains. From 
the basalt-hills one descends into the small gien of the Wad Lar, 
where the limestones occur, much altered by the intruded igneous 
rock, At this point the traveller leaves the Upper Series and enters 
upon the area of the Lower Beds, which here consist almost exclu- 
sively of friable red and purple shales with numerous brine-springs. 
The same formation continues as far as Enzel on the Wad Gadat, 
where the mountains rise abruptly to a height of over 8000 feet, and 
largely composes these mountains. 

In following the course of the Gadat a great narrow glen is 
entered, with clay-cliffs rising almost perpendicularly several 
thousand feet above the river. Owing to the decomposed condition 
of these clays, it is almost impossible to trace their bedding, but they 


202 JOSEPH THOMSON ON THE GEOLOGY OF [May 1899, 


seem to have been much folded and now dip at a variety of high 
angles. With each mile that the traveller penetrates into the heart 
of the range the scenery develops in savage picturesyueness, owing to 
the appearance of sandstones, which break the glen into more varied 
irregularities. Gradually the sandstones increase in thickness, until 
at last the shales practically disappear, and the glen narrows into 
a forbidding gorge, dangerous and painful to traverse, alike for 
man and beast. 

At length, after many hours of toilsome travelling, one reaches 
the neighbourhood of Zarktan, there confronting the central mass 
of the Atlas, opened up to view by the division of the Gadat 
gorge into a series of radiating glens which spread themselves over 
the face of the mountains. This sudden opening-up is evidently 
due to a great fault running parallel with the mountains, by which 
displacement of the rocks has taken place on a vast scale. On the 
north side of this fault, and dipping in that direction, the above- 
mentioned sandstones recur, while on the south lies a great series of 
much-weathered red and purple shales dipping in a direction opposite 
to that of the sandstones. In these have been excavated the glens- 
and valleys around Zarktan. 

Across these shales the traveller threads his way, finding it im- 
possible to trace the sequence of the beds, until, reaching the base 
of the central and highest mountain-range, he is confronted by 
another great fault and another abrupt change in the character of 
the rocks. Before reaching the last mountain-barrier the red shales 
had passed into grey, and now at the fault are seen black shales- 
with a capping of quartzites. In remarking that the hollow, of 
which Zarktan is the centre, is marked off north and south by 
faults, [am irresistibly impelled to the conclusion that primarily the 
hollow is due to a subsidence, and only secondarily to denudation. 

From this point onward, the Asif Adrar-n-Iri has carved a great 
gorge or narrow glen, not merely deep into the heart of the main. 
chain, but practically right through it, wherefore the final pass by 
which the traveller crosses lies at a comparatively low level on the 
southern side. 


Near the end of the course of the Asif Adrar-n-Iri, at a locality 
known as Titula, the glen opens out into a pear-shaped expansion,. 
and presents one of the most desolate views imaginable, in its 
absence of vegetation and its gloomy colouring, due to the black 
and grey shales and rusty quartzites. 

It is at Titula that one may first note undoubted evidence of the 
former action of glaciers in the Atlas. On all sides masses of 
débris, including huge angular blocks of quartzite, etc., meet the 
eye in such conditions and positions as admit of no other explanation 
of their existence than that of ice-action. 

At Titula also commences the final ascent of the Tizi-n-Teluet, 
by which the southern slopes are gained, and the drainage-basin of 
the Wad Draa is entered. The final barrier between the Wad Gadat 
and the valley of Teluet consists of the narrowest of mountain- 


Vol. 55.] | SOUTHERN MOROCCO AND THE ATLAS MOUNTAINS. 203 


strips. Indeed, but for a geological phenomenon, that barrier would 
not now exist, and the valley of Teluet would be drained into the 
Gadat instead of into the Draa. ‘The preservation of this barrier 
is due to the abrupt bending over of the massive quartzite which 
caps the friable shales of the central mass of the Atlas. From 
being a horizontal cap resting on shales, and therefore easily under- 
mined, it now stands as a vertical wall running across the pass, 
and subject only to the slow erosive processes of ordinary weathering. 
As it is, these processes have succeeded in cutting it down from its 
original level of over 11,000 feet to that of 8400, the height of 
the notch which forms the Pass of Teluet. 

On crossing this pass, a great sheet of basalt is seen to have 
been intruded between the sandstone-beds, as if to stiffen and 
strengthen the rocky barrier of the pass. The southern slope of 
the mountain is found to coincide approximately with the dip 
of the rocks. 

The rapid descent from the pass brings one to the interesting 
little valley of Teluet, the seat of the great mountain Kaidship or 
province of Glauwa. The rocks in which it has been excavated 
are red shales and marls, similar to those exposed around Zarktan 
and Enzel. They are seen to be much folded, and rise southward, 
to form the plateau of the Anti-Atlas. An examination of the 
valley seems to point to glaciers as the chief excavating agent. Its 
floor is now strewn with moraine-heaps and large blocks of rock, 
many of them weighing several tons. | 


Such are the chief geological characteristics of the Atlas along 
the Gadat to Teluet. We have seen that the limestones are here 
somewhat poorly developed on the outermost flanks of the mountains, 
and marked, as at Demnat, by the intrusion of a great basalt-dyke. 
Proceeding southward, these limestones are observed to give place 
to a great series of red and purple shales at Enzel, and then to a 
sandstone series. Again, the red shales at Zarktan are followed by 
an enormous development of grey and black shales, rising to an 
altitude of 12,000 feet. The latter, as mentioned above, are capped 
by a massive quartzite which, bending over, has resisted the denu- 
dation of the southern slope and the inclusion of Teluet in the 
drainage-system of the Gadat. In Teluet and the plateau to the 
south, the red and purple shales once more reappear. How far the 
three outcrops of red shales may be simply repetitions of the same 
series by folding, or are different deposits, cannot yet be determined 
with confidence; and similarly, one can only form suppositions as 
to the relations of the grey and black shales to the red and purple 
shales. At all events, they may be included provisionally in the 
Lower Cretaceous Series. Thus much, however, we know, that 
metamorphic rocks do not exist in this section, and, with the 
exception of the basalts already named, no igneous rocks either. 
Here also I first discovered evidence of undoubted glacial action, in 
the débris at the head of the Gadat glen, and the moraine-heaps and 
huge boulders of the valley of Telnet. 


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Vol. 55.] GEOLOGY OF SOUTHERN MOROCCO AND THE ATLAS. 205 


(3) The Mountains in Glauwa and Misfiwa. 


In passing westward to the next glen to be explored, the traveller’s 
route takes him across the lower and outer ranges of the provinces 
of Glauwa and Misfiwa. Leaving the Wad Gadat above Enzel, 
he crosses first a series of red shales backed by an outcrop of basalt. 
The traveller finds himself on an undulating surface, with scarped 
hills on the west, formed by a capping of limestone over the shales. 
Irregular folds bring these beds to the surface in different directions. 
One of these folds has been fractured along the anticline, and forms 
a small valley, from which the rocks dip on either side. 

An intrusion of a more northerly boss or dyke of basalt seems 
to have had something to do with these folds. At one place may be 
seen a circular depression through which runs the Wad Misfiwa, 
and in which a boss of basalt crops up, while all around the lime- 
stones dip towards the various points of the compass. 

It isin this province of Misfiwa that the boulder-beds described 
by Maw,’ aud to which he ascribes a glacial origin, are found. It 
might fairly be assumed, I think, that a glacial deposit several 
thousand feet thick could hardly be formed in any very restricted 
area. What evidence then, one may ask, is there of the con- 
tinuation of these boulder-beds eastward or westward of the locality 

where Maw examined them? I can only answer that there is 
none. <A couple of miles east of Maw’s boulder-bed, the sole 
evidence of glacial action that came under my notice was a clearly- 
defined, railway-embankment-like moraine, of no great breadth or 
thickness, extending, from behind the Zarktan Mountains, for a 
distance of 5 or 6 miles towards the plain. This moraine, with the 
exception of the glacial drift of Teluet, was by far the most im- 
portant evidence of ice-action that I ever saw in the Atlas. This 
fact makes me extremely sceptical of Maw’s theory: all the more so, 
as the situation of these boulder-beds is precisely where one would 
least expect to find such an accumulation, namely, between two 
great glens, running into the heart of the mountains, which would 
be the natural channels of the ice from the heights beyond. As 
I have not myself seen these deposits, | cannot venture any opinion 
as to their origin. 

As yet the glen of the Wad Misfiwa has not been penetrated, 
but the glimpses which the traveller obtains, on his way to Urika, 
of the mountains beyond suggest a change in the geological forma- 
tion. The bolder and more irregular outlines are eloquent of other 
rocks than shales and sandstones, and it needs but a glance at 
the débris mm the river-channel to ascertain that grauwacké and 
diorite form part of the inner framework of the great masses into 
the core of which the Wad Misfiwa cuts its way. 


i te H to Hooker & Ball’s ‘Marocco & the Great Atlas’ (1878) pp. 45&- 


206 JOSEPH THOMSON ON THE GEOLOGY OF [May 1899, 


(4) The Wad Urika. (Fig. 3, p. 204.) 


We now come to the Wad Urika, the glen of which, despite 
Sir Joseph Hooker’s and my own efforts, remains only partially 
explored. 

As in the case of the entrances to the glens of the Wads Demnat 
and Gadat, that of Urika is marked by a series of limestones thrown 
into a vertical position by an intrusion of basalt. The limestone- 
beds have but a slight development here, and are replaced on the 
opposite side of the basalt-dyke by purple shales and sandstones, 
with beds of what appears to be volcanic breccia dipping at a low 
angle northward. 

These shales and sandstones form a series of comparatively low 
hills, till some 3 miles from the plain a fault occurs, and a series 
of fine-grained red sandstones rise abruptly to a height of several 
thousand feet. Close to the fault is an outcrop of crumpled 
dark shales, which may belong to the same series as those observed 
on the Wad Gadat. Near the same point, the eastern side of the 
glen is marked by a narrow platform of débris, 200 or 300 feet 
thick, and rising to that extent in a bold precipice above the river. 
The size and shape of the contained boulders and the general 
characteristics of the deposit point to a glacial origin, but on this 
point I should not care to express any very decided opinion. 

As hitherto no traveller has been able to penetrate farther than 
the fault, one can but theorize as to the composition of the 
mountains beyond; but, to judge from the river-débris, it seems 
evident that the central mass is composed of metamorphic and 
igneous rocks. 


(5) The Wad Reraya. (Fig. 4, p. 204.) 


We now come to the important glen of the Wad Reraya, which 
penetrates to the very heart of the Atlas. It has been examined, 
not only by myself, but by Sir Joseph Hooker, the latter having 
followed the Ait Mesan or western division of its upper course, 
while I explored the Iminnen or eastern branch. 

At Taghnowt the glen is comparatively open, displaying in its 
sides outcrops of white limestone and red shale which form a small 
anticline. A mile farther up, the glen suddenly narrows, the con- 
traction being due to an cutcrop of metamorphic rocks, whose 
junction with the shales is marked by a fault. For a couple of 
miles the river winds in a narrow gorge through these rocks, till 
once more the Cretaceous Series reappears, dipping at a low angle 
southward. So far, a southerly course has been followed, but now 
the traveller turns suddenly westward, to find that he is following 
the outcrop of a basalt-dyke, from which an open valley has been 
excavated. On either hand, heaps of travelled débris are seen to 
cluster on the mountain-sides, and owe their position and origin 
probably to ice-action. 


ss = 


Vol. 55.] | SOUTHERN MOROCCO AND THE ATLAS MOUNTAINS. 207 


The westerly trend of the route followed continues as far as Asni, 
where once more the traveller turns southward into the mountains. 
A mile beyond Asni these rise abruptly, and on entering them 
the Wad Reraya divides, as before mentioned, into two branches, 
the Wad Ait Mesan and the Wad Iminnen. 

At first the traveller picks his way through a narrow gorge, cut 
out of a series of variegated sandstones, shales, and limestones, 
dipping at a low angle northward and rising to a height of over 
7000 feet above the sea. A mile or more farther up, the gorge 
widens out into a glen, when an intrusion of porphyrite alters the 
dip of the sandstones from a low northerly to a high southerly dip, 
rising to the vertical where they abut, as they do a little farther 
on, against a series of metamorphic rocks broken into by 
diorites, porphyries, etc. Once more the glen contracts into a wild 
and picturesque gorge simultaneously with the geological change. 
Gradually, as one penetrates farther into the mountains, intrusive 
masses of diorite and porphyries become more frequent, until they 
form the greater bulk of the rocks. At length, when right in front 
and at the base of the culminating heights, the Wad Iminnen turns 
eastward at a spot coincident with the reappearance of a series of 
metamorphic rocks, whose strike is parallel to the trend of the 
glen, the much-shattered slates being more easily weathered than 
the massive and compact igneous bosses. From the summit of the 
Tizi Likumpt, at a height of over 13,000 feet, it is possible to 
follow, by tracing the surface-features, the course of the combined 
core of metamorphic and igneous rocks as far as the Jebel Asif Sig 
(or Miltsin of Adm. Washington), and to assure one’s self that the 
mass of Tizi-n-Tamjurt is of similar composition. 


(6) From Amsmiz across Gindafy to Sus. (Fig. 5, p. 208.) 


Further insight into the structure of the Atlas is afforded by the 
glen of the Wad Amsmiz in the flanking mountains, and the glens 
of the Wads Nyfis and Agandice in the central massif and on the 
southern slope. 

On entering the glen of the Wad Amsmiz, the first rocks traversed 
are a thin series of white limestones and cream-coloured sandstones 
lying in vertical beds against metamorphic schists, and forming the 
northern slope of the mountains. On the traveller’s left, going 
southward, he finds the whole massif composed of much bedded and 
jointed metamorphic rocks, seamed with veins of flesh-coloured 
porphyry; while on his right similar rocks are capped by a great 
series of fine cream-coloured sandstones and limestones dipping 
slightly southward, and ending in a great fault where the mountains 
rise in another giant step. A couple of miles farther on the 
Wad Amsmiz divides, one branch spreading itself over Jebel Tezah, 
the other cutting deep into the mountains. Crossing, at an altitude 
of over 10,000 feet, the slates and grauwackés of which Jebel 
Tezah is composed, the traveller descends into the deep glen or 
valley of Gindafy, the middle mountain-course of the Wad Nyfis. 


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Vol. 55.] | GEOLOGY OF SOUTHERN MOROCCO AND THE ATLAS. 209 


Gindafy forms a cleft in the very heart of the Atlas, the central 
mass being excavated till its sides alone remain, like the lips of an 
oval cup, forming on the north the mountain-ridge of Jebel Tezah, 
and on the south that of Wishdan, both reaching a height of 10,000 
feet above sea-level. The outlet of this glen is the deep gorge of 
the Wad Nyfis. 

Geologically, however, the most remarkable feature of this 
mountain fastness is the occurrence of red flaggy sandstones with 
numerous angular pebbles scattered throughout them. These cling 
to the northern side of the valley, at an angle corresponding with 
the slope of the mountains, and seemingly bend round in a sharp 
syncline, to occupy a similar position on the opposite side of the 
valley. 

It would be difficult to account for the occurrence of this curious 
sandstone-pocket in the very heart of the mountains. Can it be 
that it was deposited in a small lake or tarn, say thrice or four 
times as large as the present area of Gindafy, in which floated masses. 
of ice laden with angular pebbles from the mountain-sides? if so, 
one must also be prepared to admit that a lateral movement of the 
opposing mountains followed the deposition of the sandstones, 
whereby they approached each other, contracting the valley of 
Gindafy to its present width and forming the syncline in which 
the sandstones lie. 

Descending into the valley, the traveller finds, near the entrance 
of the gorge which cuts through the northern mountain- barrier, a 
deposit of huge boulders and shingle more than 100 feet thick, 
due, I believe, to glacial action ; though it may have arisen by an 
accumulation of river-drift, caused by a temporary block in the 
gorge. The latter may be the real origin of the deposit, although, 
judging from the cursory examination that I was able to make of it, 
J am disposed to adopt the former theory. Crossing to the southern 
side of the small valley, one obtains a splendid insight into its 
geological constitution, thanks to the canon-like gorge of the Wad 
Agandice, one of the chief tributaries of the Nyfis, which it joins in 
the valley of Gindafy, close to the gorge which drains that valley. 

In the immediate vicinity of the entrance to the Agandice cafion 
a trachyte-dyke breaks through the red sandstones, which, as on 
the northern side of the valley, may be seen resting upon the meta- 
morphic rocks. The latter are largely composed of crystalline 
limestones, much crumpled and foliated, but chiefly ridged up in 
vertical beds. The limestones extend for more than a mile up 
the Wad Agandice, forming the northern half of Jebel Wishdan. 
Then, almost at the centre of the mountain, an abrupt change takes. 
place: the traveller leaves the metamorphic area, to find himself 
once more among the Cretaceous rocks, here dipping northward at 
angles of 25° to 30°, in great massive beds of yellowish sandstone 
and purple or blue shales intercalated with thick beds of lime stone 
At the point of junction of the two widely different formations, the 
Wad Agandice has cut a section several thousand feet deep, right. 
across the mountains. A mile or more farther up the cafion, a 


@ 7.G.S8: No. 218. P 


210 JOSEPH THOMSON ON THE GEOLOGY OF [May 1899, 


considerable thickness of diorite is seen to have been intruded 
between the Cretaceous strata. Farther up still occurs a con- 
formable bed of volcanic breccia; and then, at the point where 
the Wad Agandice branches into two, is a great intercalated sheet 
of basalt. Whether this is a contemporaneous lava-sheet, or sub- 
sequently intruded between the beds, I cannot say, but incline to the 
former view. In any case, it can be traced in a conformable sheet 
right up to the top of the mountain which overlooks the Wad Sus, 
on the south side of the Atlas range. 


In returning to the plain, the way lies down the Wad Nyfis, 
instead of across the mountains. On leaving Gindaty, the traveller 


passes at first through a narrow gorge cut out of the sandstones, - 


here hardened and altered. From the sandstones he quickly passes 
to the friable, much-jointed, and thinly-bedded schists of the meta- 
morphic area, with a corresponding broadening of the gorge into a 
tortuous glen, its many windings being due to the occurrence at 
places of more compact rocks. These schists and grauwackés mark 
the whole course of the Nyfis, till near the mouth of the glen, where 
some red sandstones and shales reappear. 

. The chief point of geological interest that calls for attention in 
the glen of the Wad Nyfis is the undoubted evidence of glacial 
action which may be remarked at several localities. Heaps of 
moraine-débris are to be seen at various elevations above the river- 
channel, and among the boulders 1 met with several well-striated 
specimens. Further evidence of glaciation is to be found in the 
smoothed and polished rock-surfaces, which have been preserved from 
_ the destructive effects of frost and rain by a covering of glacial 
débris. | 


(7) The Asif el Mel. (Fig. 6, p. 208.) 


In the section across the small province of Marossa and Jebel 
Ogdimt to Sus one finds a comparatively much greater development 
of the metamorphic area than in the section that has just been 
considered. In its main features it resembles the section displayed 
in the glen of the Wad Demnat (p. 199). Thus, a thin series of 
yellowish limestones and sandstones are seen clinging in vertical 
beds to the outer flank of the Atlas range, and resting against the 
metamorphic schists, which rise into low, broken mountain-masses, 
A few miles up the glen, a capping of Cretaceous rocks of con- 
siderable thickness appears, dipping very slightly southward and 
ending abruptly against the western continuation of the fault already 
remarked in the Amsmiz glen (p. 207). Here also the metamorphic 
rocks shoot up from beneath the sandstones, and rise into picturesque 
mountain-masses with stern, precipitous faces. There is one point to 
be noted in our examination of this fault—namely, the clear evidence 
which it presents that the upheaval of the Atlas range has not 
been solely due to the mere folding of the earth’s crust, but that 
the main force or chief line of weakness lay along the central axis 
of the mountains; and that, in consequence, the internal parts 


~— 


Vol. 55.] SOUTHERN MOROCCO AND THE ATLAS MOUNTAINS. 211 


were pushed up without always carrying the adjacent beds with 
them. To some such movement as this must be due the step-like 
arrangement of the flanking-ranges, the series of faults at the base 
of these steps, and the crumpling and crushing of the rocks at such 
faults. The last-named phenomenon is well seen at the junction of 
the Cretaceous with the metamorphic rocks in the Marossa district. 
Here the sandstones and limestones, which cap the lower ranges 
on the north and lie almost horizontally, are contorted in the most 
remarkable manner along the line of fault, where the metamorphic 
rocks have been forcibly thrust up to a height of several thousand 
feet. 

The same feature may be seen all along the fault to the Amsmiz 
glen. A tributary of the Asif el Mel has excavated a consider- 
able gorge along this line of fault, showing the result of the 
upheaval. At one place, the Cretaceous beds are crumpled into 
sharp curves, in another the beds are ridged up vertically, while 
50 yards from the fault the same rocks are seemingly undisturbed. 
In passing, we may note that in this gorge a very good example 
of a terminal moraine can be seen, made up of great polished 
subangular blocks in a matrix of fine material. At one time, this 
moraine dammed back the streams and formed a small tarn, now 
drained off. 

From Marossa, right across to the Sus Valley, one finds nothing 
but metamorphic schists, grauwackés, quartzites, and crystalline 
limestones, and, if the Cretaceous rocks are anywhere represented on 
the southern slope of the range, they must occur at a very low 
altitude. Standing on the peak of Jebel Ogdimt, overlooking the 
Sus plain, I could perceive no feature in the scenery which even 
suggested their existence. 


(8) From Imintanut to Sus. 


We now come to the last section, no longer, however, across the 
Atlas range, but along its western end, where it merges into the 
plateau-land of Mtuga and Haha. 

On leaving the district of Imintanut, the mountains are entered 
by a narrow gorge, which immediately widens out into a glen. 
This narrowing is the result of the greater power of resistance to 
denuding agencies presented by a thick, hard,.cream-coloured lime- 
stone, dipping at an angle of about 60° northward, coincident with 
the outer slope of the mountains, and presenting a scarped face on 
the opposite side, capping at the same time the more friable shales 
and sandstones. A rich fossiliferous bed appears here, a circum- 
stance of which unfortunately I was not able to avail myself. 

Immediately beyond the gorge the glen divides into three. Ifthe 
traveller follows the western branch, it is found to be excavated along 
the line of junction of the Cretaceous and metamorphicrocks. At the 
head of the glen we again turn southward, still skirting, however, the 
line of junction of the two formations; but the Cretaceous is now 
represented by the red sandstones and shales of the Lower Series. In 

P2 


212 JOSEPH THOMSON ON THE GEOLOGY OF [May 1899, 


this way the traveller crosses the glen of the Wad Msira, and then 
finds himself, after ascending a little, at the commencement of a 
long shallow valley trending southward and draining into the Wad 
Sus. Again are the valley and the junction of the two formations. 
coincident, and moreover the junction marks a line of fault where the 
metamorphic rocks have been thrust up, to the disturbance of the 
Cretaceous Series along the line of upheaval. The last-named rocks 
have been tilted at various angles, while a short distance from the 
fault the beds are scarcely disturbed from their horizontal position. 

South-west of the village of Ida Uziki the Atlas begins to tail 
off very rapidly, but here again recurs the same characteristic 
upheaval of the metamorphic rocks without disturbance of the 
general horizontality of the red sandstones and shales—except along 
the immediate line of uplift, where, of course, the Cretaceous rocks 
have been much disturbed and carried up on the flanks of the 
upheaved metamorphic series. 

The glen of the Asif Ig marks the end of the Atlas range, for here 
that range not only merges into the general level of the plateau, 
but the metamorphic rocks finally disappear beneath the Cretaceous... 


Discussion. 


The PrestpEnt explained that the manuscript of the foregoing 
communication was found, in 1898, among some of the papers of 
the late Mr. Topley, and was handed over by his son to the speaker. 
The name of the author did not appear to be marked on it, but the 
initials ‘J. T’ were inserted below some faint pencil-marks on a 
wrapper. He thought that it must have been written by that able 
observer, the late Joseph Thomson, and, on its being shown to 
Dr. Scott Keltie, Secretary of the Royal Geographical Society, 
he at once identified the handwriting. 

On comparing the manuscript with Thomson’s book and paper, 
Proc. Roy. Geogr. Soc. vol. xi (1889) pp. 1-16, it was found that 
though various geological notes were scattered through these, the 
present communication contained much more than these notes, and 
it also has the advantage of putting all together. He thought 
therefore that it should be read before the Geological Society, espe- 
cially as Morocco is a country of which so little is known. 

Mr. Gipson said that, as a student of African geology, he 
felt impelled to bear testimony to the Author’s excellent geo- 
logical work in Africa. His notes on the geology of the routes 
traversed by him in the Great Atlas and Southern Morocco were an 
acceptable addition to the knowledge ot these Jittle-known regions. 
The absence, so far as yet shown, of older or younger Paleozoic 
formations on the flanks of the Atlas is noteworthy, as these deposits 
are well represented south of that chain. The east-and-west faults 
mentioned in the paper are parallel to the main lines of dislocation 
in Algeria. 

Prof. Hurx felt grateful to the President for rescuing this 
important paper from oblivion and bringing it before the Society. 


Vol. 55.] | SOUTHERN MOROCCO AND THE ATLAS MOUNTAINS. 213 


In consequence of the extreme difficulty attending exploration 
in Morocco, any addition to our knowledge of the geology of the 
Atlas range was of especial interest and reflected high honour 
on the courageous explorer. The structure of the Moroccan Atlas 
appeared to the speaker to be in harmony with that of Northern 
Africa generally, where very ancient crystalline and metamorphic 
rocks were immediately succeeded by Cretaceous strata. As the 
Author observed, there was an entire absence of Palzozoic rocks, 
and we might add, of Triassic and Jurassic. Such was also the case 
in the Nile Valley and Arabia Petra, with the exception, in the 
latter country, of a slight representation of Lower Carboniferous 
limestones (first recognized by Mr. H. Bauerman) at distant intervals. 
The speaker considered that the Atlas range formed the margin 
towards the north of the great Cretaceous basin which was spread 
over the Desert of Sahara, and stretched across the Nile Valley ; 
and later, that of the Eocene Nummulitic sea. 
Prof. Warts also spoke. 


214 DR. G. J. HINDE ON RADIOLARIA IN CHERT {May 1899, 


12. On Rapionaria in CuERt from Caypons Farm, Muuiion Parise 
(Cornwatt). By Grorer Jennines Hinps, Ph.D., F.BS., 
F.G.S. (Read February 1st, 1899.) 


[Prats XVI] 


I, InrRopuctory REMARKS. 


Avr the time of the discovery of the Radiolarian Chert-beds on Mullion 
Tsland in 1893, described by Messrs. Fox & Teall,' the extension of 
the beds to the neighbouring mainland was suspected, but no traces: 
of them could be found. Mr. Howard Fox, however, continued his 
search for them, and in the early part of 1897 he discovered a small 
exposure of chert in situ, in a road-cutting near the base of the 
hill leading north from Chypons and about 1 mile north by east 
of Mullion Church. The chert appears as several bands interbedded 
with the clay-slates of the district. Detached blocks of chert had 
previously been noticed on the surface of the fields and built into 
the hedges in the neighbourhood, but up to Mr. Fox’s discovery the 
rock had not been recognized or recorded in place. Mr. Fox caused 
microscopic sections to be prepared from different portions of the 
chert-bands, and these showed the presence of radiolaria in 
considerable numbers, resembling in general appearance the forms 
present in the chert from Mullion Island. In some portions of the 
chert, however, the radiolaria were preserved in an unusually 
perfect condition, showing their latticed structure and spines very 
distinctly, and Mr. Fox forwarded to me the specimens, and some 
careful drawings by Miss Lister of the organisms, in order to see 
whether any fresh knowledge respecting the character of the radio- 
laria could be obtained. As some of the forms appear to be new, 
and as they are more favourably preserved than any previously 
described from the Paleozoic rocks of this country, I have ventured 
to bring them before the Society. 

- The Chypons cherts which yield the radiolaria are massive, dark to 
black rocks, traversed in all directions by microscopic quartz-veins,. 
so numerous that the original dark portion of the rock is now 
divided up into small irregular patches, having a_ brecciated 
appearance. In some of the microscopic sections, the areas: 
oceupied by the veins are as large as those of the dark chert. The 
groundmass of the chert is composed of cryptocrystalline silica, with 
much dark material, probably some compound of iron. This dark 
substance is either evenly distributed in the rock, or it has an im- 
perfect laminate or wavy arrangement, which seems to follow lines 
of cleavage-pressure. The radiolaria, for the most part, are casts. 
only, without any definite bounding-walls, their outlines being 


? Quart, Journ. Geol. Soe. vol. xlix (1893) p. 211. 


Vol. 55.] FROM CHYPONS FARM, MULLION PARISH. 215 


indicated by the dark material of the groundmass, while the 
interior of the tests has been infilled with clear silica, sometimes 
eryptocrystalline, at others of fibrouschalcedony. Not infrequently, 
the opaque material in the groundmass has taken the place of the 
clear silica in the hollow of the test, and the organism then 
appears as a small circular or oval blot in the section. In the 
forms showing the structural details, these alone have been replaced 
by the opaque substance and are thus clearly defined against the 
clear silica infilling the test. The radiolaria so favourably 
preserved are, unfortunately, restricted to very small portions of 
the rock, and in a microscopic section of the chert we may find a 
group of the organisms in one corner of the slide with spines and 
lattice-mesh nearly complete, while the rest of the slide contains 
only structureless forms. 


IL. Descrrprion oF THE RADIOLARIA. 


Class RADIOLARIA, Miiller. 
Subclass SPUMELLARIA, Ehrenberg. 
Order SPH AAROIDEA, Haeckel. 


Genus SriegmospH @RA, Haeckel. 


The test is a simple hollow latticed sphere, with radial rods ex- 
tending from the centre to the inner surface of the wall. 


SrIGMosPH@RA ECHINATA, sp. nov. (PI. XVI, fig. 1.) 

Test small, with a very delicate lattice-mesh and minute sub- 
equal rounded pores. Here and there are small conical surface- 
spines. The interior rods are now partially broken and displaced. 
Diameter of test, 0-1 mm.; of the pores, 0°005 mm.; length of 
surface-spines, 0°015 mm. Rare. 


Genus CarrospuH RA, Haeckel. 


The test consists of two concentric latticed spheres connected by 
radial bars. 


CARPOSPHHRA NANA, Sp. nov. (Pl. XVI, fig. 2.) 


Test small, with delicate mesh and minute rounded pores. Only 
the outline of the inner sphere is shown; it is connected with the 
cortical test by five or six short bars. Diameter of test, 0°065 mm. ; 
of the inner sphere, 0°03 mm. A somewhat larger, but otherwise 
very similar form, occurs in the chert from Mullion Island, which 
might be included in this species.' 


1 Quart. Journ. Geol. Soc. vol. xlix (1893) p. 217 & pl. iv, fig. 3. 


216 DR. G. J. HINDE ON RADIOLARIA IN CHERT [May 1899, 


Genus STIGMOSPHZROSTYLUS, Riist. 


The test is a simple latticed sphere, with radial rods in the 
interior and two opposite radial spines. 


STIGMOSPH ZROSTYLUS INHQUALIS, Sp. nov. (Pl. XVI, fig. 3.) 

The pores of the mesh are circular or oval, and very unequal in 
size ; only the bases of the radial spines are preserved. The 
internal radii are apparently six in number; they are now displaced 
in the specimen. Diameter of test, 0°125 mm.; width of pores, 
0-006 to 0°02 mm. Rare. 


Order PRUNOIDEA, Haeckel. 
Genus CenELuipsis, Haeckel. 
The test is a simple latticed ellipse, without radial spines. 


CENELLIPSIS SETOSA, sp. nov. (PI. XVI, fig. 7.) 


Test a regular oval, with minute subequal rounded pores and 
small surface-spines. The width of the mesh is somewhat less than 
that of the pores, There is considerable difference in the size of 
the forms referable to this species. A large specimen measures 
0°27 mm. by 0°21 mm., and the pores are 0°01 mm. in width; 
an average example, such as that figured, is 0-185 by 0°15 mm. in 
length and breadth, and the pores are about 0-007 mm. wide. 


CENELLIPSIS FAVoOSA, sp. nov. (Pl. XVI, fig. 8.) 

Test oval, surface without spines, the pores rounded or oval, very 
unequal in size, the smaller interspersed among the larger. 
Length, 0:195 mm.; breadth, 0°15 mm.; pores, from 0:015 to 0-025 
mm. in width. The form from Mullion Island, referred to as sp. a’ 
but not named, is probably identical with this species. 


CENELLIPSIS scITuLA, sp. nov. (Pl. XVI, fig. 6.) 


The pores of the test are circular or oval, unequal in size; the 
surface is furnished with small spines. Length, 0°16 mm.; breadth, 
0-12 mm.; pores, 0-006 to 0:02 mm.in width. The smaller dimen- 
sions of the pores and the surface-spines distinguish this from the 
preceding species. 


Genus StavuRopRuPPA, Hinde. 


The test consists of two concentric elliptical latticed shells, with 
four radial spines disposed crosswise in two axes, but not always 
at right angles. 


SravropRupea NucuLA, Hinde. (Pl. XVI, figs. 9 & 10).’ 

Both the cortical and medullary tests are regularly oval ; the pores 
are very small, rounded or occasionally subangular, and apparently 
of the same size in the inner as in the outer test ; in some examples 
they are arranged in oblique rows. ‘The spines are stout and 


* Quart. Journ. Geol. Soe. vol. xlix (1893) p. 217 & pl. iv, fig. 4. 
2 Ibid. vol. lv (1899) p. 52 & pl. ix, fig. 7. 


Vol. 55.] FROM CHYPONS FARM, MULLION PARISH. 217 


elongate, but they are very rarely preserved complete. In a small 
specimen the cortical test measures 0°08 by 0:065 mm. in length and 
breadth, and the medullary 0°04 mm. in length, while a large form 
measures 0-12 by 0085 mm., with the inner test 0-04 by 0-035 mm. 
The pores are about 0:005 mm. in width. The longest spine is 
0-11 mm. in length, and 0-03 mm. in thickness at the base. This 
species is very common; the examples vary in size, but the mesh- 
pores are of a similar character in all. The type of the species occurs 
in the Devonian rocks of New South Wales. 


SravropRruppa Foxir, sp. nov. (Pl. XVI, figs. 11, 12 & 13.) 


The test is oval, the pores circular or oval and apparently similar 
in both cortical and medullary shells; the radial spines are very 
stout; those of the longer axis are for the most part in the same 
line as the axis, but the transverse spines are markedly oblique in 
direction. An average specimen is 0:2 by 0°14 mm. in length and 
breadth; the medullary shell is 0-06 by 0:045 mm.; and the longest 
spine 0-14 mm. in length by 0:035 mm. in basal thickness. The 
pores measure 0-006 to 0°008 mm. in width. This form is less 
common than St. nucula, from which it differs mainly in its larger 
size, thicker walls, and the pronounced oblique direction of the 
transverse spines. 

One example (fig. 11) is referred with some doubt to the present 
species on account of its smaller size, which brings it near to the 
preceding species, St. nucula. The outer shell measures 0°15 by 
0-1 mm., and the inner 0-05 by 0:035 mm. Only the bases of the 
radial spines are shown, while the delicate mesh of the inner shell is 
beautifully preserved. 

This species is named in honour of my friend Mr. Howard Fox, 
F.G.8., who has so perseveringly worked at the radiolarian and 
other rocks of Cornwall and Devon. 


Genus DRUPPALONCHE, ! gen. nov. 


The test consists of two concentric, elliptical, latticed shells, with 
three radial spines. 


DRUPPALONCHE CLAVIGERA, sp. nov. (Pl. XVI, fig. 14.) 


The test is regularly ovai; the medullary shell is about one third 
the diameter of the cortical, andthe pores are minute. In the centre 
of the medullary shell is a small spicular body with three rays, 
round which there is a small group of pores. The radial spines 
are relatively thick and terminate obtusely, but probably they are 
incomplete. They are disposed at unequal distances apart. The 
cortical shell measures 0°13 by 0-1 mm. in length and breadth; the 
medullary, 0°05 by 0°04 mm.; the longest spine is 0-1 mm., 
with basal thickness 0°04 mm. The space between the shells, in 
the specimen figured, is in part filled with the opaque material of 
the matrix. Rare. 


1 Druppalonche=Olive with spines: dpta7a, \oyx7n. 


218 DR. G. J. HINDE ON RADIOLARIA IN CHERT [May 1899, 


DRUPPALONCHE OvATA, sp. nov. (Pl. XVI, fig. 15.) 


Test evenly oval, the medullary shell about one-fourth the diameter 
of the cortical, the pores minute and apparently similar in both 
outer and inner shells; the spines are somewhat slender, tapering, 
and at unequal distances apart. Cortical shell, 0°13 by 0-1 mm. in 
length and breadth; medullary, 0-035 by 0-03 mm. ; longest spine, 
0-1 mm., and thickness at base, 0°015 mm.; pores, 0:005 mm. in 
width. Rare. 


Order DISCOIDEA, Haeckel. 


Genus TrocHopiscus, Haeckel. 


The test is a simple, lenticular, latticed shell, with a variable 
number (ten to twenty or more) of radial spines extending from the 
equatorial margin. 


Trocnopiscus (?) pusrus, sp. nov. (Pl. XVI, figs. 4 & 5.) 


Test small, round or oval in outline; pores few, circular or oval, 
very unequal in size, the smaller interspersed among the larger. 
There are four or five stout conical radial spines, at unequal distances 
apart, and apparently not all in the same plane. Diameter of test, 
0:07 mm.; pores, 0°005 to 0:02 mm. in width; length of spines, 
0:05 mm. Radial rods are present in the interior of the disc. In 
the irregular character of the pores this species resembles TJ'rocho- 
discus proavus, Rust, from the Carboniferous rocks,’ referred to by 
Riist as representing the simplest form of the genus. The spines in 
the form here described are fewer in number than in the type of 
the genus, and it is doubtful whether it can properly be included. 
therein. 


The following is a list of the forms described in the foregoing 
pages :-— 
SPHZROIDEA. 
Stigmosphera echinata, sp. nov. 
Carposphera nana, sp. nov. 
Stigmospherostylus inequalis, sp. nov. 
PRUNOIDEA. 
Cenellipsis setosa, sp. Nov. 
C. favosa, sp. nov. 
C. scitula, sp. nov. 
Staurodruppa nucula, Hinde. 
St. Forti, sp. nov. 
Druppalonche clavigera, gen. et sp. nov. 
Dr. ovata, sp. nov. 
DiscomEA. 
Trochodiscus (2?) dubius, sp. nov. 


Though all the foregoing forms are here regarded as new, two of 
the eleven species, Carposphera nana and Cenellipsis favosa, were 
recognized in the Mullion Island chert, but not named. 

The genus Cenellipsis is the most numerously represented in 
the Chypons chert, just as in that of Mullion Island. Next to 
Cenellipsis, forms of Staurodruppa are the most abundant. This: 


1 ¢ Paleontographica,’ vol. xxxviii (1892) p. 164 & pl. xxi, fig. 1. 


Quart. Journ.Geol.Soc.Vol.LV. P1.XVI. 


mo 


SN caer: 


Mintern Bros imp. 


A.T. Hollick delet lth. 


RADIOLARIA FROM MULLION PARISH (CORNWALL). 


; Xi 


AW X 200 


ee 


Vol. 55.] FROM CHYPONS FARM, MULLION PARISH. 219 


genus has only recently been constituted for some radiolaria in 
the Devonian rocks of New South Wales,’ and it is interesting 
to note that one of the Australian species is also represented at 
Chypons, where it occurs probably on a lower geological horizon. 

No Cyrtoidal radiolaria have been recognized in the Cornwall 
chert, and other organisms than radiolaria are apparently absent 
in this rock. | 


EXPLANATION OF PLATE XVI. 


[The specimens are from the chert, of presumed Ordovician age, at Chypons: 
Farm, Mullion Parish (Cornwall). The slides containing the specimens belong 
to Mr. Howard Fox, F.G.S., who intends to present them to the British 
Museum (Natural History). All the figures are enlarged to the same scale of 
200 diameters. | 

Fig. 1. Stigmosphera echinata, sp. nov. Only the bases of the radial spines 
are preserved. 

2. Carposphera nana, sp. nov. - 
3. Stigmospherostylus inequalis, sp. nov. The radial spines are im- 
perfect. 

Figs. 4 & 5. Trochodiscus (?) dubius, sp. nov. 

Fig. 6. Cenellipsis scttula, sp. nov. 

- 7. Cenellipsis setosa, sp. wov. 
8. Cenellipsis favosa, sp. nov. 

Figs. 9 & 10. Staurodruppa nucula, sp.nov. The radial spines are imperfect. 

Hig. 11. Stawrodruppa Foxit, sp.nov. The radial spines are all broken away ; 
the form is seen in section. 

Figs. 12 & 13. Stawrodruppa Foxii. The specimens are seen in section; the 
radial spines are imperfect, and the fourth spine is wanting 
in both examples. 

Fig. 14. Druppalonche clavigera, gen. et sp. nov. Seen in section. 

15. Druppalonche ovata, sp. nov. Seen in section ; the radial spines are 
imperfect. 


Discussion. 


Dr. Hicks said that the additional evidence brought forward in 
this paper was most interesting, in its bearing on the physical 
conditions under which these chert-rocks were deposited. ‘There 
seemed to be no doubt that the area at the time was an oceanic one, 
and that the radiolaria lived there and were not drifted specimens. 
He thought that the rocks were not older than of Arenig age; but 
it was unfortunate that other fossils, by which the age might be 
satisfactorily determined, had not as yet been found. 

Mr. C. Rei pointed out the exceptional importance of these 
floating oceanic organisms for the correlation of rocks over widely 
separated areas. He was glad to find that good specimens frum 
Mullion could now be described and figured. 

Dr. H. Woopwarp also spoke. 

The Avrnor, in reply to Dr. Hicks, said that he had not touched 
upon the question of age of the rock, since the evidence from the 
radiolaria does not lead to any definite conclusions. There could 
be no doubt that the radiolaria were im situ, for they would not 
have retained their delicate structures if they had been exposed to 
drifting at the sea-bottom. He thanked the Fellows for their 
reception of his paper. 


1 Quart. Journ. Geol. Soc. vol. ly (1899) p. 51. 


220 - GRAVEL AT MORETON-IN-THE-MARSH. [May 1899, 


13. Graver at Moreron-1n-1HE-Marsu (GLOUCESTERSHIRE). 
By 8S. 8. Buckman, Esq., F.G.S. (Read February 1st, 1899.) 


[ Abstract. | 


Tuer Author describes certain gravels of Triassic débris and flints 
at Moreton-in-the-Marsh, with special reference to an upper bed 
wherein the fragments are mostly in a vertical position, some of 
them having their heavier ends uppermost. He theorizes that the 
vertical materials were the droppings from melting ice floating 
down a large river. This river, formed out of one or more of the 
original consequents of the Thames system, existed before the valley 
of the Warwickshire Avon had been excavated. By one branch, 
possibly the upper Trent, it drained the Pennine range; by another, 
possibly the upper Severn, the Welsh hills. Ice formed in the 
upper waters—in these highlands—enclosing débris, and when a 
thaw occurred, it floated down to the lower parts of the river. 

The Author notices certain flirts obtained from the gravels. 
Those from the upper bed are sharply angular, even most finely 
pointed, and are quite unabraded. They strengthen the theory of 
ice-transport, and it is evident that they have not been moved by 
stream-action since their deposition, otherwise they would show 
signs of wear. The flints from the lower bed do seem to point to 
some such condition of subsequent removal: they have their edges 
worn, and are in some cases battered, and peculiarly flaked as if 
artificially worked. 

The Author surmises that the date of the gravel, if formed by 
a river-system as supposed, is Pliocene. 


14. On the Occurrence of Pessius of ScHort-Rock from the Souru- 
west of Enetanp in the Drirt-prposirs of SourHERN and 
Eastern Eneranp. By A. E. Sazrer, Esq., B.Sc., F.G.S. 
(Read February Ist, 1899.) 


[ Abstract. ] 


A ser of twelve representative specimens, consisting essentially of 
quartz and tourmaline, have been examined by Prof. Bonney, who 
informs the Author that they consist mainly of felspathie grits, 
schorl-rock, etc., similar rocks to which occur in the South-west 
of England. The most westerly point at which the pebbles have 
been detected is on Great and Little Haldon Hills, 800 feet above 
Ordnance datum, where they are of larger size, more abundant, and 
coarser-grained than elsewhere. Thence they are traced to the 
north and south sides of the Thames Basin, and into East Anglia at 
Walton-on-the-Naze, Aldeburgh, etc. There is a general decrease 
in height in the deposit in which the pebbles occur, in passing from 
west to east, and the pebbles appear to have taken two main 


Mol? 55. | PEBBLES OF SCHORL-ROCK IN DRIFT-DEPOSITS. 223 


courses—one along a peneplain west to east from Dartmoor, the 
other from south-west to north-east across England. ‘The pebbles 
are absent from the Weald and from the district around Bagshot, 
from the Hampshire Basin and its bounding hills (with the ex- 
ception of the extreme south), and from the highest and presumably 
oldest gravels north of the Thames. 


Discussion (ON THE TWO FOREGOING PApERs). 


Mr. C. Rui pointed out that irregular decalcification or settle- 
ment in gravels tends to cause the longer axes of the stones to 
become vertical, and that this vertical position, therefore, must not 
be taken as evidence of glacial action. With regard to Mr. Salter’s 
specimens of schorl-rock, he was sorry to see that the Author still 
insisted on confounding gravels of Eocene age, at Haldon, Hardy’s 
Monument, and Dorchester, with much later Drift-deposits of other 
areas. 

Mr. Marner considered Mr. Salter’s record of tie distribution of 
schorl-rock pebbles more valuable than the theory put forward to 
account for that distribution. Schorlaceous pebbles occurred not 
uncommonly in the Birmingham Drift, as shown by some specimens: 
which the speaker exhibited, but it did not need a peneplain from 
the South-west of England to bring them to the Midlands, for they 
were clearly derived from the Bunter Conglomerate. Mr. Waller had 
described (and his microscopic slides were on the table) the petrology 
of tourmaline-bearing pebbles both from the Bunter and the Midland 
Drift. Similarly, the pebbles farther south, instead of proving a 
north-eastern peneplain, were Bunter pebbles, which may have ori- 
ginally come from Cornwall but had not seen their parent-rocks since 
Triassic times. The Author’s own statement bore this out, when he 
said that, while schorl-rock pebbles were absent in the Wealden 
area, they occurred, associated with northern rocks, at Kingston 
Hill, Dartford Heath, and Crayford. 

Mr. H. W. Moncrron, referring to the paper by Mr. Salter, first 
expressed a doubt as to the relationship between the gravel at the 
Hockett, 350 feet above the sea, and the valley or gap at Goring. 
Secondly, if he understood aright, the Author accounted for the 
presence of the schorl-rock pebbles in Suffolk and Essex as follows: 
1st. They had been carried by river-action from the far south-west 
to, say, the Bedford district ; 2nd. They had been subsequently re- 
drifted through gaps in the Chalk into Suffolk, ete. If that were so, 
the speaker thought that there should be remains of the deposit 
near Bedford, formed during the first of these stages, and he asked 
whether any such remains had been found. Thirdly, the speaker 
had himself found schorl-rock in the Bunter of Nottinghamshire ; 
and he asked whether the Author could point to any distinction 
between the schorl-rock pebbles of the Suffolk, etc. gravels and those 
of the Bunter Beds. 

Mr. R. 8. Herries thought that, before Mr. Salter’s theory could 
be accepted, he ought to show that the specimens of tourmaline-rock 


222 GRAVEL AT MORETON-IN-THE-MARSH. [May 1899, 


could not have come from any other quarter except the south- 
west. 

Mr. E. A. Marri referred to a paper read in 1887 by the 
Rey. A. W. Rowe, in which he stated that he had found quartz- 
tourmalines, containing schorl in abundance, in the neighbourhood 
of Felsted in Essex. He alluded to the wide range over which 
Mr. Salter’s researches had taken him, and from which specimens 
had been gathered, and complimented him upon the work that he 
had accomplished. 

Dr. Hicks said that the evidence produced by Mr. Salter seemed 
to show that the pebbles of schorl-rock in the Drift on and near the 
shore of the English Channel had come from the south-west; but he 
could not agree with his conclusions that the pebbles of schorl-rock in 
the Drifts of Hertfordshire and North Middlesex had also come from 
the same direction. The associated pebbles in the latter areas were 
of northern derivation ; therefore it was more reasonable to suppose 
that the schorl-rock had also come from some northern source. 

Mr. O. A. Surussore said that the gravel at Moreton-in-the- 
Marsh was interesting, but its level was comparatively low. He 
had obtained from it one flint-flake which might be regarded as 
a ‘scraper. He did not, however, recognize signs of chipping in 
any of the specimens exhibited. 

Prof. W. W. Warts also spoke. 

The CHarrman (Prof. Bonney) said that, before calling upon 
Mr. Salter to reply, it was only just to him to say that he (the 
speaker) happened to be fairly well acquainted with the Bunter 
pebbles of the Midlands and with the tourmaline-bearing rocks, 
both of igneous and of sedimentary origin, in Devon and Cornwall, 
in the latter of which, so far as he knew, they were more abundant. 
In the Midland Bunter tourmaline occurred in pebbles, which might 
be called felstones, and in sundry dark, rather compact, quartzose 
sedimentaries. These, however, so far as he knew, were rather 
markedly different from the tourmalinized sedimentaries of the 
south-west, which also occurred as pebbles in the Budleigh Salterton 
conglomerate. The pebbles described by Mr. Salter, as a rule, 
resembled the latter and not the former type. 

Mr. Satrer thought that the chief points in Mr. Buckman’s paper 
were not new. He agreed with the Author in regarding the 
deposit as fluviatile, probably of Pliocene age. The presence of 
Triassic débris and flint, coupled with the absence of Drift composed 
of Jurassic rocks, was due, in his opinion, to the fact that the 
Jurassic rocks were covered up by Cretaceous strata, which have 
since been denuded. The action of floating ice and the indications 
of a cold period, noted by the Author, were in accord with the 
speaker’s experiences in Southern England. He did not see any 
trace of man’s work in the flints exhibited. 

Replying to the remarks on his own paper, he said that he did 
not agree with Mr. Reid in assigning an Eocene age to the 
high-level Drifts of Dorset and Devon. If that were so, the 
Chalk escarpment would, he thought, have been cut back much 


Vol. 55.] PEBBLES OF SCHORL-ROCK IN DRIFI-DEPOSITS. 223 


farther. In reply to Mr. Matley, he did not deny the presence 
of Bunter pebbles from the Midlands in the Drift. They occur 
plentifully in the Lea valley, but differ from those described in 
the paper. The peneplain required by his argument existed in 
Pliocene or earlier times, and was probably much broken up during 
the Glacial period. In reply to Mr. Monckton, he said that the 
gravels at the Hockett were deposited when the escarpment was 
not cut so far back, and when the Thames flowed at a higher 
level, where the Goring gap now is. Similarly there are no 
remains of the old peneplain and its associated gravels in the 
Midlands, because the cutting-back of the Chalk escarpment has 
destroyed them. The finding of these pebbles over so wide an 
area could not be called negative evidence. He thanked the 
Fellows for their reception of his paper. 


224 MR. ARNOLD-BEMROSE ON THE GEOLOGY OF [ May 1899, 


15. Grotocy of the AsHBovurne g Buxton Branca of the Lonpon 
g Norra Western Rartway :—Asupourne to Crake Low. 
By H. H. Arwoxp-Bemroszp, Esq., M.A., F.G.S. (Read. 
January 4th, 1899.) 


[Puates XVII & XVIII—Sections]. 
Con rents. 


AL, PEmibrod WehiOM: 2% cits... deesnfesicis selnole ce tad unten ep sake eee ea eee eee 224 
TL, Deseription. of the Cuttings ./)......s¢-..222seecs sree: eee 225 
(1) Sandybrooke. 
(2) Alders Farm, 
(3) Ashes Farm. 
(4) Bentley Hall. 
(5) Washbrook. 
(6) Tissington. 
(7) Highway Close Barn. 
(8) Crake Low. 
Nit. Orake daow Quarry go.se<sced sche coadeateemirescemer scene case ee eee 231 
LV... Petroetaphy of, the Rocks, ccicc.onneo reese none ateesenenr antes eee eee 233: 
(1) The thick Ash-bed. 
(2) The Hjected Blocks in the thick Ash. 
(3) The thin Tuffs and Tufaceous Limestones above the 
thick Ash. 
(4) The Limestones. 


Ll. InrRopuUctTion, 


Tue railway from Ashbourne to Buxton, when completed, will 
cover a distance of about 20 miles. It runs nearly due north, 
passing near the villages of Fenny Bentley, Thorpe, Tissington, 
Parwich, and Alsop-en-le-Dale, and will enable visitors from the 
north to reach conveniently some interesting parts of the limestone- 
district, besides rendering the beauties of Dovedale more accessible to 
the tourist. 

For the first 6 miles the railway runs on the Bunter Beds, Boulder 
Clay, and Yoredale rocks, and for the remaining 14 miles on the 
Mountain Limestone. The northern section, from Buxton to Parsley 
Hay, was completed several years ago, and I believe that no geolo- 
gical description of it was published. The southern section is now 
in progress of construction. The cuttings as far as Crake Low, about 
6 miles from Ashbourne, are practically completed, but farther 
north there are several through which a passage has not yet been 
made. For this reason, I confine myself in the present paper to 
a description of the geology of the line from Ashbourne to Crake 
Low. 

Undoubtedly the most interesting portions are the three cuttings 
near Tissington, Highway Close Barn, and Crake Low. Sir A. Geikie,' 
speaking of the latest traces of volcanic activity in Derbyshire, 
points out that ‘though no contemporaneous tuffs have yet been 


Ancient Volcanoes of Great Britain,’ vol. ii (1897) p. 18. 


Vol. 55-1 THE ASHBOURNE AND BUXTON RAILWAY. 225 


found among the Yoredale rocks, coarse agglomerates do traverse 
the Yoredale group at Kniveton.’ A careful examination of these 
cuttings has enabled me to fill this gap in our geological know- 
ledge. The railway-excavations bring to view no less than four 
exposures of bedded ash, the existence of which in the Yoredale 
rocks of this district had not been previously known. They also 
show a fine series of contorted limestones and shales, which occupy 
a horizon above the ash. ‘This series of rocks contains numerous 
intercalations or thin beds of tuff, and many of the limestone-beds 
in it have voleanic lapilli disseminated through them. Thus they 
afford a proof of the existence of a vigorous, followed by an inter- 
mittent, volcanic activity, contemporaneous with the deposition of 
the Lower Yoredale Beds. 

After crossmg under Church Street, Ashbourne, the railway 
passes through the Bunter Beds in a tunnel, 370 yards long. 
Unfortunately, I was unable to visit the tunnel before it was 
bricked in, and, therefore, cannot give any details regarding the 
structure of the rocks through which it is cut. 


Il. DEscriprion oF THE CurrtINes. 


(1) Sandybrooke. 


The first cutting opposite Sandybrooke is about 730 yards long, 
and shows a tbick deposit of Boulder Clay. It contains pieces of 
sandstone, grit, and Mountain Limestone, the last often having a 
well-polished and striated surface. The greater part had been sloped 
down before I saw it, but the boulders are numerous and project 
above the surface of the Clay. 


(2) Alders Farm. 


The second cutting, opposite Alders Farm, about 250 yards long, 
is in Boulder Clay. It contains numerous boulders of Mountain 
Limestone, grit, sandstone, shales, chert, and igneous rocks foreign 
to the county. 


(3) Ashes Farm. 


The third cutting, opposite Ashes Farm, Fenny Bentley, about 
330 yards long, is in Boulder Clay, which in one place is seen to 
rest upon a bed ofsand. A large number of foreign igneous rocks 
were found here, in addition to boulders from the Carboniferous 
sedimentary rocks. 

These three cuttings were visited by me after they had been 
practically finished; but the others as far as Parsley Hay, where 
the new railway joins the previous extension from Buxton, were 
frequently examined during the course of excavation. By this 
means, much information was gained about the stratigraphy of 
the beds, which would have been missed had the cuttings only been 
seen when finished. 


Qed. G.S. No. 218. Q 


226 MR. H. H. ARNOLD-BEMROSE ON THE GEOLOGY oF [May 1899, 


(4) Bentley Hall. 


The fourth cutting, opposite Bentley Hall, about 690 yards long, 
is in a tough Boulder Clay which contains many well-polished and 
grooved Jimestone-boulders. At the end nearer Tissington the Clay 
rests upon shales. Immediately north of the cutting, in an old 
quarry near the point where the railway crosses the Buxton road, is 
an exposure of shales and limestones dipping in an easterly direction. 
The limestones are black in the interior, but covered by a weathered 
erust, which gives them the appearance of sandstone: they contain 
bands of chert in which foraminifera occur. 


(5) Washbrook. 


The fifth cutting, east of Washbrook Cottage, about 290 yards 
long, is in Boulder-Clay at either end, underneath which shales and 
thin limestones are seen for'a short distance in the centre. 

The railway now makes a curve to the east, and describes nearly a 
semicircle round the eastern part of the village of Tissington. After 
leaving the cutting in Boulder Clay, it crosses a small valley in the 
soft ash, and enters the sixth cutting. 


In the three cuttings to which the remainder of this paper is 
devoted, four exposures of thick ash may be seen, each overlain by 
shales and limestones, with intercalations of tuff. For the sake of 
distinction only, and not implying thereby any difference in compo- 
sition, the term ash will be restricted to these four exposures, while 
the thinner intercalations of volcanic detritus will be called tuffs. 


(6) Tissington. (Pls. XVII & XVIII.) 


This cutting is about 1060 yards long, and may be naturally 
divided into three nearly equal portions—the northern, central, and 
southern. <A bed of ash about 144 feet thick, below which is seen 
a few feet of cherty limestone on the eastern bank of the cutting, 
occupies the whole of the central portion, and dips beneath the 
contorted shales and limestones in the two other parts of the cutting, 
The cherty limestones below the ash are now only visible on the 
eastern side, where they are bent into an anticline: they were 
formerly to be seen across the railway. During the excavation they 
were seen dipping at an angle of 40° across the cutting, and thus only 
2 feet of the uppermost beds appeared at the bottom of the eastern 
bank under the ash, which dipped with and overlay them. After 
a short time they were hidden by débris. The line at this point 
passes through a dome, composed either of the upper cherty beds 
of the Mountain Limestone, or of the basement-beds of the Yoredale 
Series. The ash is exposed for a much greater distance north of the 
dome than south of it, and there are indications that this part of the 
voleanic deposit has been bent into a long syncline and anticline 
before it dips under the shales in the northern portion of the cutting. 


Vol. 55.] THE ASHBOURNE AND BUXTON RAILWAY. 227 


It has, in fact, been subjected to the same foldings as the beds 
above and below it. 

The ash is generally of a rather coarse texture, has in many places 
a distinct lamination, and contains numerous blocks of a dark blue or 
grey amygdaloidal rock, distributed irregularly throughout its mass. 

A thick bed of volcanic ash also occurs at the southern end of the 
cutting. It is much decomposed, and only the upper 36 feet of it 
is seen. It is overlain by a succession of shales and thin lime- 
stones (some of which are tufaceous) with thin partings of tuff. 
The limestones often contain chert, Productus, and encrinite-stems, 
and in places are dolomitized. The beds at first dip in a north- 
easterly direction and then become bent into a number of troughs 
and arches. The railway turns northward, the beds dip south-west- 
ward, and under the shales one again finds the bedded ash. ~ 

The occurrence of four exposures of ash in this and in the next 
two cuttings led me to try and ascertain whether they ail belonged 
to the same deposit, or were due to several eruptions. They all 
occur within a mile of Tissington, and one would hardly expect to 
find, within so short a distauce in this district, evidence of several 
great outbursts, each followed by a succession of more feeble 
eruptions. 

The structure of the ground, the numerous folds into which the beds 
have been thrown, and the fact that the country is largely covered by 
Drift, render it difficult, if not impossible, to connect directly the four 
outcrops of ash by tracing their relations in the field. I have already 
mapped a large area of ground covered by the second exposure of 
ash, through which the central portion of Tissington cutting passes, 
in order to trace it, if possible, to its source. But it would be beyond 
the scope of the present paper to enter into any further details 
regarding the surrounding country, and that part of the subject 
must be left until I have more fully worked out the rocks of the 
district. I have been able, however, to trace this ash in a northerly 
direction, up to within a short distance of the third exposure of ash, 
which is seen in the Highway Close Barn cutting (p. 229). 

In order to ascertain whether the two beds of ash in the Tissing- 
ton cutting belonged to the same deposit, | made careful measure- 
ments of the thickness of the beds, at right angles to the bedding- 
planes, from one end of the cutting to the other. I measured from 
the southern ash up to the top of the first syncline, then down to 
the base of the adjacent anticline, and so on, to the second exposure 
of ash: the total up-and-down measurement differed by 6 feet. I 
then plotted ten vertical sections to scale, and found that the ash at 
the second exposure was 6 feet lower in the series than that at the 
first. The measurements were then checked in several ways in 
the field, and the difference of 6 feet was found to hold good. 

A comparison of the sections showed that there were several well- 
defined beds of limestone, one of which appeared six times, and 
another three times in this part of the cutting above the ash. The 
lower of these two beds is denoted by the letter A, and the upper bed 
by the letter B, in Pl. XVII, fig. 1, and in Pl, XVIII, figs. 1 & 2. 

a2 


228 MR. H. H. ARNOLD-BEMROSE ON THE GEOLOGY oF [May 18coQ, 


The distance of A above the ash was 222 feet at the southern end. 
The bed A was easily traced through this part of the cutting, and at 
its last appearance was found to be 287 feet above the second 
exposure of ash. It varies in thickness, thinning out from 33 feet 
at the southern end to 1 foot at the northern. It contains chert, 
and in many places volcanic lapilli occur disseminated in it. 

The upper beds, marked B, are easily distinguished by the fact 
that they are thicker than the other limestones in the series. They 
are first found near the southern end, at a height of 593 feet above 
the ash. They are seen again in the middle limb of the first fold, 
and then at the top of the cutting immediately beyond the tem- 
porary bridge over which the road to Matlock passes. They 
contain encrinite-stems, Productus, and sometimes lapilli. Like 
the bed A, they vary in thickness: in a distance of about 43 yards, 
measured parallel to the original bedding-plane, they thin out 
from 92 to 6 feet, and when seen for the third time are 74 feet 
thick. 

There is, therefore, no doubt that the first and second exposures 
of ash in this cutting are of one and the same bed, the shales and 
thin limestones above it having been bent into a number of small 
folds which amount in effect to a syncline. 

The total thickness of these beds above the ash in the first part of 
the cutting amounts to 94 feet; and the intermittent showers of 
lapilli were continued, until beds at least 66 feet above the main 
body of ash had been deposited. It will be noticed from vertical 
section No. 1 (Pl. XVIII) that the limestone becomes thicker and 
the shales decrease in quantity towards the top of the series. Chert 
is found in lenticles and in bands in many of the limestones, some 
of which are dolomitized, and others of which are dark and fine- 
grained. Dr. Wheelton Hind found fish-teeth in the thicker beds 
of limestone.’ 

The beds in the northern part of the cutting above the second 
exposure of ash consist of shales and thin limestones, often ashy, 
folded into two troughs and crests. A thickness of 97 feet of strata 
is seen above the thick ash-bed, and the intercalated tuffs were found 
up to a height of 61 feet in the series. 

It is impossible to correlate the thin limestones in the northern 
and southern portions of the cutting. They vary in thickness, and 
are probably not persistent for so great a distance, wherefore some 
of them thin out and disappear while fresh limestones make their 
appearance. There is, however, one band of limestone in the northern 
part, which may be the same as that seen six times in the southern 
part. Itis 13 feet higher in the series, namely, 30 feet above the 
ash-bed, and is marked C in Pl. XVII, fig. 1, andin Pl. XVIIL, fig. 3; 
it is seen twice in this part of the cutting. 

An ashy limestone, marked D in the above-mentioned sections, 54 
feet above the ash, is seen three times, and a well-marked group of 
cherty limestones (in which galena was found) near the top of the series 


1 ¢Deser. of Section in Carb. Limest. Shales at Tissington, N. Staffs Field- 
Club, Noy, 17th, 1897, 3 pp. 


Vol. 5c. THE ASHBOURNE AND BUXTON RAILWAY. 229 


appears once in this part of the cutting. At the northern end, the 
railway runs through beds about 54 feet above theash. After I had 
plotted the vertical and horizontal sections, and arrived at the fore- 
going conclusions, I received from Dr. Wheelton Hind his description, 
which deals with the section in Tissington cutting only. He states 
that the Toadstones seen at the south and centre of the cutting 
belong to ‘the same bed, so that the whole of the first part is one 
complete synclinal basin, itself thrown into many minor folds by 
contortions,’ and concludes that ‘the beds immediately overlying 
the Toadstone’ are not ‘ identical with those which rest onit in the 
first part of the section.’ 

The line passes along a small embankment, and soon enters the 
Highway Close Barn cutting. Between these two cuttings the beds 
probably form a syncline. 


(7) Highway Close Barn. (Pls. XVII-XVIII 
& text-figs. 2-3, p. 230.) 


This and the next cutting pass through ground which was mapped 
as Mountain Limestone by the officers of the Geological Survey. The 
beds consist of limestones and shales, which lie above the third 
exposure of ash at the northern end of the cutting. They have been 
folded into an anticline and syncline. A thick group of ashy lime- 
stones, which occupies the middle of the seriesin the cutting, is seen 
three times. The limestones at first dip south-eastward, then bend 
sharply over, dipping north-westward, and are brought up again on 
the other side of the syncline. A reference to Pl. XVII, fig. 2, and 
Pl. XVIII, fig. 4, will explain the position and sequence of the beds. 
Above the ash 86 feet of strata may be seen. ‘The limestones are 
_ thicker, lie more closely together, and have thinner partings of shale 
than is the case in the Tissington cutting. There are, however, 
several thick beds of shale with a few thin limestone-bands. Thin 
beds of tuff are also intercalated with the shales, and lapilli are 
numerous in some of the limestones, up to a height of 80 feet above 
the thick ash-bed. The limestones are often cherty, and contain 
Productus. The upper part of the ash-bed is seen at the northern 
end of the cutting, below the shales and limestones. Some portions 
of it are finely laminated, others are of a coarser texture, and a few 
ejected blocks are found init. After crossing the valley which runs 
down to Shaws Farm, the railway enters the next cutting. 


(8) Crake Low. (Pls. XVII-XVIII & text-fig. 1, p. 230.) 


About the first half of this cutting isin Mountain Limestone, 40 
feet of which is seen. The upper beds are thin and cherty, and 
there is an absence of shale. They dip 15° southward, and probably 
lie conformably beneath the thick ash in the last cutting; they may 
belong to the same series of beds, the top of which is seen below 
the thick ash in the Tissington cutting. Productus abounds, and 


230 MR. H, H. ARNOLD-BEMROSE ON THE GEOLOGY OF [May 1899, 


lead-ore was found in the lower and more massive beds. . The lowest 
visible beds of these limestones are faulted against the fourth expo- 
sure of thick ash. The limestones end abruptly, and abut against a 
clay containing several large pieces of limestone. ‘The clay is soon 
succeeded by bedded ash dipping north-westward on the western 
bank, and north-eastward on the eastern bank of the cutting. The 


Fig. 1.—Diagrammatic section across the northern end of Crake Low 
cutting, showing an anticline in the limestones above the ash. 


Fig. 2.—Diagrammatic section across the northern end of Highway 
Close Barn cutting: shales and limestone above the ash. 


Fig. 3.—Diagrammatic section across the southern end of 
Highway Close Barn cutting. 


E, 


a=shales. 6=limestones. 


ash and the beds above it must have been thrown down at least 40 
feet. ‘This ash was blue when freshly exposed, and some silicified 
beds in it were very hard; like that in the other cuttings, it soon 
weathers to arusty red. It is succeeded by tufaceous limestones, 
with very thin clay- or shale- or tuff-partings. No thick shale-beds 
were seen. The thin beds immediately above the ash are much 
contorted, and some of the thin layers of tuff very soon thin out, 


Vol. 55. | THE ASHBOURNE AND BUXTON RAILWAY. 231 


their place being taken by limestone, which is often tufazeous; and 
thus sections across the beds, only a few yards apart, would vary 
much in detail. 


III. Craxe Low Quarry. (PI. XVIII, fig. 6.) 


Two fields west of the last cutting, and about 100 feet above it, are 
two old quarries on the south-eastern slops of Crake Low. Though 
at first sight they seem to be beyond the limits of the ground 
covered by the present paper, a short description of them may be 
fittingly introduced, since they throw some light on the sequence of 
the beds in the last two cuttings. 

The smaller quarry has not been worked for a long time, but the 
beds in it are similar to those in the larger one. ‘The limestones from 
the latter were formerly burnt for lime, but now are broken up for 
road-metal. Forty feet of a very interesting succession of beds is 
seen. A reference to Pl. XVIII, fig. 6, shows them to. consist of 
limestones, many of which contain volcanic material, separated by 
thin beds of tuff: they generally contain Productus and encrinite- 
stems. A limestone is seen to be free from lapilli in one place, 
while a foot away the same bed is crowded with them; or a lime- 
stone free from volcanic sediment in its centre often contains. 
lapilli near its bottom and top surfaces. ‘This is especially the case 
if there be a layer of tuff or tufaceous limestone above and below it. 

A little more than halfway down the face of the quarry is a bed 
of coarse tuff, 2 feet thick, with tufaceous limestone above and 
below it. From this tuff I obtained numerous Productus-shells and 
a block of igneous rock. The block was very vesicular, and of the 
Kniveton type. Some of the layers of tuff intercalated with the 
limestones and shales in the three cuttings already described contain 
Productus-shells and fragments of large encrinite-stems, and are 
very similar to the bed of tuff in this quarry. 

Some of the tuff-partings thin out very quickly. In one place a 
bed of tuff and tufaceous limestone, together about 9 inches thick, 
thin out in a distance of 6 feet, aud are replaced by limestone free 
from volcanic ejectamenta. The beds at the bottom of the quarry 
where the section was measured are of a massive bluish-grey 
limestone containing foraminifera, and are free from ash. A few 
yards away they pass into thinner beds, and contain lapilli. No chert 
was found, and very few partings of shale were noticed. It was an 
examination of this quarry which led me to search carefully for 
intercalations of tuff in the limestones and shales above the four 
exposures of ash in the cuttings. The beds dip in a westerly 
direction into Crake Low, and le stratigraphically above the 
Mountain Limestone in the Crake Low cutting. 


We are now in a position to discuss briefly the relations of these 
beds to those in the two adjacent cuttings. The thick ash in the 
Highway Close Barn cutting can be traced for a short distance in 
the fields towards the quarry, and there is little doubt that it is 


232 MR. H. H. ARNOLD-BEMROSE ON THE GEOLOGY OF [May 1899, 


continued and lies between the quarry and the Mountain Limestone 
in the Crake Low cutting, though I have not been able yet to find 
it in situ on the slope of the hill. On the eastern side of the line 
the ash can be traced only for a short distance from the Highway 
Close Barn cutting, because the limestones above it dip rapidly down 
towards the east and cover it up. 


The rocks through which the Highway Close Barn and Crake Low 
cuttings have been made form on the whole a long narrow dome, 
with minor basins in it, through the long axis of which the railway 
runs. Fig. 1, p. 230, gives a section across the railway, seen in the 
limestones above the ash at the northern end of Crake Low cutting, 
before the rocks were cut through. 

Fig. 2 (p. 230) is a similar section across the northern end of 
Highway Close Barn cutting in the shales and limestones above the 
ash, and fig. 3 (p. 230) a section across the same cutting at the 
southern end. This dome brings up the small inlier of Mountain 
Limestone seen in Crake Low cutting. 

The tufaceous limestone and shales in the Highway Close Barn 
cutting are apparently carried up by the dip to Crake Low Quarry, 
and then brought down by the fault which passes near the farm of 
the same name. It would seem, therefore, that the deposits of ash 
in the two cuttings, which are the third and fourth exposures of ash, 
belong to the same bed. I have shown that the two beds of ash in 
the Tissington cutting, which are the first and second exposures, are 
really one bed, and so far as the evidence obtained by mapping 
goes, it points to the conclusion that the second and third exposures 
are also of the same bed. We are, therefore, compelled to conclude 
that there is only one thick deposit of ash in the three cuttings, 
succeeded by limestones and shales with intercalations of tuff. 

A comparison of the vertical sections (Pl. X VIII) shows a difference 
in the beds above the ash in the three cuttings. The limestones 
become thicker, and the shales decrease as one goes northward from 
sections 1 to 5; in one place shale and thin limestones have been 
deposited above the thick ash, and in another numerous beds of lime- 
stone with thin shale-partings: in the former is a preponderance 
of shallow-water deposits, and in the latter a preponderance of rocks 
formed in deeper water. If my contention that only one thick ash- 
bed is present be correct, there was deposited immediately after the 
great outburst in one place what would be called Lower Yoredale 
Beds and what were mapped as such by the officers of the Geological 
Survey; andin another place, not far distant, what are lithologically 
more like the upper beds of the Mountain Limestone Series and 
lave been mapped as such by the officers of the Survey. These beds, 
though totally unlike in character and apparently belonging to 
different series, are really of the same age. 

In only one place is the ash-bed exposed to view from top to 
bottom, namely, in the middle of the Tissington cutting. Here 
it is about 144 feet thick. In the three other places in which it 
appears, only the upper portions are seen; a thickness of about 


Volk 55.1 THE ASHBOURNE AND BUXTON RAILWAY. 233 


36 feet is exposed at the southern end of Tissington cutting, about 
A2 feet in Highway Close Barn cutting, and about 96 feet in Crake 
Low cutting. 

According to the Geological Survey Memoir ‘a fault ranges 
along the south-west side of the valley of Parwich Leys, the lime- 
stone rising in a bold cliff and dipping away from the shales.’' 
The evidence given by the last two cuttings described removes any 
necessity for the fault by Highway Close Barn and Crake Low, which 
is marked on the Geological Survey map, Sheet 72 N.E. Though the 
beds do indeed dip into the hill at Crake Low Quarry, they soon 
bend over in an anticline, and dip eastward under the shales in the 
Parwich Leys Valley. 


TY. Prerroeraruy or tHE Rocks. 


(1) The thick Ash-bed. 


When freshly cut into, the ash is light-blue or grey, a colour due 
to the presence of pyrites, but after a short exposure to the air it 
changes to a rusty red, and later to a greenish-brown. 

The ash is distinctly bedded, and the different beds vary much in 
texture. The lapilli consist of fragments of a pumiceous rock, from 
microscopic dimensions up to an inch or so in diameter. The 
outlines of the lapilli are very irregular, some being more or less 
rounded, while others, in the more finely laminated portions of the 
deposit, are elongated in a direction parallel to the bedding, and the 
vesicles in them are often drawn out in the same direction. The 
outer surface of the lapillus generally cuts across the vesicles. When 
fresh, the lapilli are either isotropic or exert only a feeble action on 
polarized light, and are, therefore, glassy or a devitrified glass. 
Sometimes they are altered to calcite or dolomite, or to a palagonitic 
substance, and in one cutting are very much silicified. They are 
never crystalline. (1 have found only one lapillus in which felspar- 
microlites are present.) There are no small fragments of basalt or 
dolerite among them, and their structure has no counterpart among 
the lavas of Derbyshire. 

The vesicles are filled with crystalline calcite, iron-oxide, a light- 
green fibrous material which exerts only a feeble action on polarized 
light, and sometimes with an isotropic substance. 

In some cases, as in the ash at the southern end, and in the 
greater part of that at the centre of Tissington cutting, the lapilli 
are crowded closely together, and only separated by what is probably 
a volcanic dust. In others, as in the Highway Close Barn and 
Crake Low cuttings, where it was possible to obtain less weathered 
specimens, they are cemented by crystalline calcite. 

Pyrites is largely distributed throughout the ash. The latter has 
generally a specific gravity of about 2°5 when fresh, but in one 
specimen of ash which contains an unusually large amount of 
pyrites the specific gravity is 2°9. 


1 North Derbyshire, 2nd ed. (1887) p. 32. 


234 MR. H. H. ARNOLD-BEMROSE ON THE GEOLOGY OF [May 1899, 


The lower part of the thick ash-bed is seen only in Tissington 
cutting. It is made up of small pieces of a vesicular rock about 
1 inch in diameter, closely packed together. These are spherical or 
discoidal in shape, and when weathered are spotted with carbonate 
of lime, which at a short distance gives the rock the appearance 
of an amygdaloidal lava. They are not bombs, but large lapilli, 
which have probably derived their present shape from having been 
rubbed together in the volcanic vent, prior to their final ejection. 

A thin slice from one of these spheroids, ? inch in diameter, was 
examined under the microscope. During the process of grinding it 
was broken up into small pieces, which looked like separate lapilli ; 
but on further examination it was seen that the outlines of any two 
in juxtaposition correspond in such wise that if placed close together 
they would fit exactly. The structure is very similar to that of the 
minute lapilli described above. Some of the vesicles are circular in 
section. Others are very much elongated, but their longer axes bear 
no relation to the outer boundary of the fragment. On the contrary, 
the boundary breaks across the vesicles, as in the case of the smaller 
lapili, and also in that of the larger included blocks described 
below. 

In Crake Low cutting some parts of the ash-bed are very hard. 
Both lapilli and matrix have been altered to silica, calcite, and 
pyrites: the various stages in this alteration can be traced. A 
fairly fresh specimen is composed of isotropic lapilli in a calcitic 
matrix. Cryptocrystalline silica then appears in small patches 
the lapilli are next altered to calcite, and embedded in calcite and 
eryptocrystalline silica with pyrites; and, in the final stage of 
alteration, the rock is entirely composed of the above-mentioned 
minerals, the outlines and vesicular structure of the lapilli being 
visible in ordinary light. 

In the upper part of the thick ash, at the northern end of 
Highway Close Barn cutting, several beds of a fine-grained and 
laminated mudstone were seen. The specific gravity of two 
specimens was 2°32 and 2°4, which is less than that of the ash. 
One had the appearance of a dull, fine-grained basalt, though it was 
not crystalline: the other was softer and less coherent. Under the 
microscope they are almost structureless, and contain iron-oxide, 
with a small quantity of crystalline calcite, but no traces of lapilli. 
There is no microscopic evidence of their volcanic origin. 


(2) The Ejected Blocks in the thick Ash. 


The ejected blocks found im the ash are generally rounded or 
subangular in shape, and either vesicular or amygdaloidal. When 
the vesicles are filled with a dark material, the rock looks (on a 
freshly-fractured surface) very much like limestone. ‘The blocks vary 
in size from several inches up to about a foot in diameter, and are not 
arranged in beds, but scattered irregularly through the finer ash. 
They differ from the small fragments in the ash by being finely 


Vol. 55. | THE ASHBOURNE AND BUXTON RAILWAY. 239 


crystalline, and not so glassy. They are similar to the biocks in the 
‘Kniveton vent, the structure of which was described by me ina 
former paper read before this Society,’ but the felspars are much 
smaller, and there are very few traces of olivine. Their specific 
gravity varies from 2°53 to 2°62. 

Two blocks found in Highway Close Barn cutting are probably 
ejected fragments of the older ash which solidified in the vent, and 
were blown out by subsequent eruptions. They consist of isotropic 
and well-preserved lapilli in a cement of cloudy calcite. 


(3) The thin Tuffs and Tufaceous Limestones above 
the thick Ash. 


Among the thin limestones and shales which lie above the thick 
ash-bed are numerous intercalations of tuff, varying in thickness 
from about 7 inch to 2 feet. They are very similar to the thick 
ash just described, but differ from it in containing Productus and 
large encrinite-stems: they weather rapidly, and are generally too 
incoherent for slicing. 

A bed of coarse tuff (2 feet thick) in Crake Low Quarry, and 
containing Productus semireticulatus and an ejected block, proved 
sufficiently hard for a thin slice to be prepared. It is light-brown, 
with light-grey patches, in a hand-specimen. Under the micro- 
scope, 1t consists of numerous lapilli, altered to crystalline calcite, 
unevenly distributed throughout the slice, and mingled with small 
pieces of previously consolidated limestone, which often contain a 
foraminifer or a portion of one, or of some other organism. All 
these fragments are cemented together with crystalline calcite. 
The vesicular block, several inches in diameter, found in this bed is 
similar to those from the thick ash in the cuttings. 

In the thick ash-bed there appears to be an absence of ordinary 
mechanical sediment, while in the limestones and thin partings of 
tuff above this bed there is a commingling of volcanic and ordinary 
sediment in rapidly varying degrees, even on the same horizon, 
within a short distance. Some of the limestone-beds are free from 
tuff, and others contain varying proportions of volcanic ejectamenta ; 
and thus what is a limestone free from volcanic sediment in one 
place will pass into a tufaceous limestone or a shelly tuff in another. 
Some beds, which in a hand-specimen resemble a hard tuff, when 
examined under the microscope are seen to contain so many fossils 
that they may be considered as a tufaceous limestone. 

The lapilli distributed through the limestones are almost invariably 
altered to crystalline calcite or dolomite and oxide of iron. Only 
one small lapillus, in a limestone 20 feet above the ash in the 
northern part of Tissington cutting, contained felspar-microlites. 
When altered to calcite or dolomite they are hard to distinguish 


1 “Microsc. Struct. of Carb. Dolerites & Tuffs of Derbyshire,’ Quart. Journ, 
Geol. Soc. vol. 1 (1894) pp. 638, 639. 


236 MR. H, H. ARNOLD-BEMROSE ON THE GEOLOGY OF [May 1899, 


in polarized light, and their vesicular structure is seen with such 
difficulty in ordinary light that they might be easily overlooked. 

The limestones in which they are embedded generally contain 
foraminifera, shell-fragments, and small encrinite-stems. In many 
cases the tufaceous limestones consist (in addition to volcanic 
material) of worn shell-fragments and small pieces of a previously 
consolidated limestone, which sometimes contain a few quartz- 
crystals. Patches of cryptocrystalline silica are present in some 
specimens. Parts of a limestone-bed are often dolomitized. 

In a few cases the lapilli are isotropic, as, for example, in a 
tufaceous limestone resting upon the top of the ash at the centre of 
Tissington cutting, in a tuff (10 inches thick) immediately above 
it, and also in a tuff-parting (6 to 8 inches thick) 2 feet above the 
thick ash in Highway Close Barn cutting and separated from it by 
shales. 

The tufaceous limestones in Crake Low Quarry are similar in every 
respect to those in the cuttings. About 28 feet from the top of the 
quarry is an interesting bed of banded limestone, which shows a 
series of rapid alternations of ordinary and volcanic sediment. 
Above and below it are 2 and 3 inches of tuff respectively, which 
die out in a distance of 6 feet to the south, and are replaced by 
limestone. 

In a hand-specimen nine black bands occur in a space of less 
than 1 inch, then follows 2.inch of limestone free from bands, and 
lastly seven more bands in the space of an inch. Under the 
microscope the bands consist of elongated lapilli, coloured with 
iron-oxide: these are isotropic, and often are penetrated by and 
contain small rhombohedra of dolomite. 


(4) The Limestones. 


The limestones interbedded with the shales vary considerably in 
structure and texture, and often contain layers of chert. Some of 
them are coarse in texture and composed mainly of encrinite-stems 
and Productus; others are dark, fine-grained, and free from fossils. 
Many of them contain foraminifera. The coarse and fine-grained 
varieties are often found in different layers of thesame bed. Many of 
the limestone-beds are partly or wholly dolomitized, and in extreme 
cases all traces of fossils are obliterated. When the dolomitized 
beds are weathered they have a sandy feel and appearance, and on 
a cursory examination might be mistaken for a sandstone. They 
sometimes contain cryptocrystalline silica. 

Two thin slices of the compact limestone below the ash-bed in 
the centre of Tissington cutting were examined. The rock is 
a very close-grained and partly crystalline limestone, with a few 
small encrinite-stems. 


Altogether, forty-six thin slices were examined from the rocks in 
the three cuttings and Crake Low Quarry. 


2 
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ee 


Quart. Journ, Geol. Soc. Vol. LV, Pl. XVII. 


Fig. 1.—Section through Tissington Cutting. 


=—~ 


<== 


RS ~. 


LIMESTONE 


LIMESTONE-the beds above the Ash are often tufaceous. 


Horizontal Scale 
BEDDED ASH, 0 10 2030 40 50 60 70 80 90 {00yards 
— 


SHALE and thin Limestones. with Tuff partings, 


a a TIS 5 ee Da iE WP tinea 


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Vol. 55.] THE ASHBOURNE AND BUXTON RAILWAY. 237 


EXPLANATION OF PLATES XVII & XVIII. 


Puate XVII. 


Figs. 1-3. Horizontal sections through Tissington, Highway Close Barn, and 
Crake Low cuttings, on the scale of 40 yards to the inch. 


Puate XVIII. 


Figs. 1-6. Vertical sections of the beds above the thick ash, between Tissington 
and Crake Low, on the scale of 12 feet to the inch. 


Discussion. 


Prof. Huxt said that he had listened with interest to the paper, 
knowing the district of Derbyshire to which it referred. He 
reminded the Fellows that on the Geological Survey maps and 
sections there were two outpourings of lava intercalated among 
the Carboniferous Limestones—the upper lava being near the top 
of the limestone-series. These had been originally traced by the 
late Sir Warington Smyth. e was not quite clear, from the 
Author’s account of the ash-beds, whether or not these represented 
the uppermost of the two lava-flows mapped by the officers of the 
Survey, or whether they were the products of a third and later 
eruption. One of the finest examples of submarine volcanic energy 
at the close of the Carboniferous Limestone period in the British 
Isles was to be found in County Limerick, at Cahirconlish, where 
no fewer than ten successive eruptions.of lava and ash-beds were 
interposed between the limestone and the overlying ‘ Yoredale’ 
shale. These beds appeared to be representative of those described 
by the Author. 

Prof. Sortas remarked that an examination of the specimens on 
the table recalled the association of calcareous sands and volcanic 
detritus now frequently presented by islands in the Pacific. He 
had seen precisely similar ball-like lapilli in Oahu, where in some 
cases they formed beds deceptively resembling lava-streams. Similar 
basaltic glass, passing into palagonite, occurred in association with 
detrital limestones in some of the islands of Torres Straits. In one 
of the slides of limestone exhibited by the Author structures were 
to be seen superficially resembling sponge-spicules. The speaker 
also called attention to a series of contemporaneous basaltic rocks 
associated with the Carboniferous Limestone of Limerick: these 
had been studied in detail by Prof. Watts. 

Mr. LamerucH commented on the strongly-marked difference 
between the character of the Glacial Drift in the sections described 
by the Author and that of the country a few miles farther south, 
and on the importance of this difference as an indication of the 
direction of ice-flow. He asked what other Boulders besides local 
rocks were found in this Drift. 

Mr. Srrawan thought that the Author had ede two important 
points. In the first “place, he had proved the contemporaneous age 
of the igneous series by the existence of limestones containing ashy 
material. Contemporaneous igneous rocks were now known in so 


- 238 THE ASHBOURNE AND BUXTON RAILWAY. [May 1899, 


many parts of England, in the Carboniferous Limestone, that they 
evidently could not all have proceeded from one source. There 
seem to have been a number of small vents scattered over an area 
that was undergoing prolonged subsidence. In the second place, 
the Author had shown that this outburst occurred in the so-called 
Yoredale Series, and therefore at a later date than any known in 
the Isle of Man,in other parts of Derbyshire, or in Somerset: in all 
these districts the contemporaneous igneous rocks lay some distance 
dewn in the limestone. 

Prof. Warts pointed out that the volcanic rocks of Limerick 
appear to occur on about the same horizon as those of Derbyshire. 
The Limerick basin is surrounded by a series of small volcanic 
necks, and thus the point mentioned by the previous speaker is 
also paralleled in Ireland. 

The Prestpenr, Mr. Barrow, Mr. TEatt, and Dr. Hinpe also 
spoke. 

E The Aurnor thanked the Fellows for the kind way in which they 
had received his paper. In reply to Mr. Barrow, he said that what he 
(the Author) had described as a thickly-bedded ash was undoubtedly, 
from its occurrence in the field and behaviour under the microscope, 
a fragmental rock and not a lava. In reply to Prof. Hull, he said 
that the old idea of the restriction of the term toadstone to two 
beds of lava no longer applies; that the term includes rocks from 
volcanic necks of the puy type, from lava-flows, from volcanic ashes, 
and from intrusive sills. 

In answer to Mr. Lamplugh, he said that similar Drift was found 
in other parts of the county. The foreign igueous rocks were 
probably derived from the Lake District. He had not gone more 
fully into the subject of the Drift in the cuttings, as Mr. Deeley 
was working out various problems connected with the direction of 
travel of the Drift. 


Vol. 55.] A SILL AND FAULTED INLIER IN TIDESWELL DALE. 239 


16. On a Stu and Favuxrrep Inter in Trpeswert Date (Dersy- 
SHIRE). By H. H. Arwnoztp-Brmrosr, Esq., M.A., F.G.S. 
(Read March 8th, 1899.) 


[Puares XIX & XX.] 


ConrTENTS. 
Page 
EMME OGIMCTOT: |. 2.) saan, {bec atrertee Sy sates emma ebsites emia le 239 
II. Description of the Area and its Geological Structure... 241 
III. The Lavas and Intrusive Dolerite of the Inlier............ 242 
PPE REOSPA PIN sscciinalcs ie utes cana snas sow anuup ase aits sre woweesaey 245 
(a) The Intrusive Dolerite or Sill. 
(6) The Vesicular Lava above and below the Sill. 
(¢) The Columnar Clay. 
(d) The Limestone below the Igneous Rocks. 
(e) The Tuff near the Northern Fault. 
(7) The Laya-flows south of the Inlier. 
Weasnnimary and Comclusions:.....sctasscyecsseseccasss rots an 249 


I, Iyrropvucrion. 


Tue object of this paper is to describe an interesting series of 
igneous rocks, about 4 mile south of Tideswell, and between that 
village and the valley of the Wye (Geol. Surv. 1-inch map, 81 S.E.). 

The old marble-quarry in Tideswell Dale has been known to 
geologists for many years, on account of the baked columnar clay 
underlying the toadstone, which was at one time well exposed. 
Numerous excursions have been made to the quarry, and several 
papers have been written on it, but no detailed work appears to 
have been done with the view of ascertaining the relation of the 
toadstone to the clay and the limestone-beds. The quarry was 
worked about 50 years ago for its fine coralline marble, but was 
abandoned because of the unavoidable expense of removing a great 
thickness of toadstone, in order to get at the limestone below it. 

In 1870 a paper was read before this Society by the Rev. J. M. 
Mello, describing the section exposed in the quarry.’ In the same 
year Mr. Edward Wilson? and Mr. Edwin Brown ? each contri- 
buted a paper on the same subject to the Geological Magazine. 
According to these observers, a bed of clay, which was often 
columnar, rested on the coralline marble. It varied in thickness 
from 5 to 12 feet, and the columns in it sometimes attained a length 
of 8 or 9 feet, and a breadth of 6 inches. Above the clay was a 


1 «On an Altered Clay-bed & Section in Tideswell Dale,’ Quart. Journ. 
Geol. Soe. vol. xxvi (1870) pp. 701-704. 

2 «Altered Clay-bed & Sections in Tideswell Dale,’ Geol. Mag. 1870, 
pp. 520-523. 

3 «On a Columnar Clay-bed in Tideswell Dale; etc, ibid. pp. 585-586. 


240 MR. H. H. ARNOLD-BEMROSE ON A SILL AND ={ May 1899, 


band of vesicular and amygdaloidal toadstone from 1 to 2 feet 
thick. This was succeeded by about 20 feet of large blocks of hard 
dolerite or amorphous basalt with spheroidal structure in places. 

Both Mr. Wilson and Mr. Brown mention a thin bed of ash 
below the clay; the former writer considered that the clay was due 
to an overflow of volcanic mud, and that it was coextensive with 
the toadstone in this part of the valley. I have been unable, how- 
ever, to find any trace of the ash-bed. According to Mr. Brown, the 
clay-bed varied in thickness in different parts of the quarry. This 
is substantiated by a man who worked at the marble-quarry more 
than 30 years ago, and who told me that the clay varied greatly 
in thickness, and was entirely absent in some parts of the quarry. 
Further evidences of this variation in thickness are to be seen in 
other parts of the Dale. 

t is important to notice that the greater portion of the toadstone 
then seen was described as a hard, compact dolerite or basalt, with 
only about 1 foot of vesicular rock or amygdaloidal rock below it. 
The vesicular rock above the hard mass higher up the hillside does 
not appear to have been examined. 

Mr. G. Fletcher described the toadstone in the quarry and also 
some slabs of finely laminated limestone, the upper surfaces of 
which were traversed by a network of fine cracks. He considered 
that the cracks were sun-cracks in a coral-mud.} 

Mr. J. Ward called attention to the spheroidal blocks of dolerite, 
which he considered mainly owed their shape to a chemical change 
in the rock, due to weathering.’ 

The first four observers attributed the induration of the clay to 
a lava-flow, but do not appear to have noticed the great extent to 
which the subjacent limestone has been marmorized. Though 
Mr. Brown speaks of it as a coral-reef converted into a bed of hard, 
massive limestone marble, it is uncertain whether he a!luded to the 
metamorphic effects of the igneous rock upon it, or whether he 
merely used the word in the local sense for a hard limestone 
employed for the same purpose as marble. He considered that, from 
the varying depths to which the column descended in the clay, 
important deductions might be made as to the persistency of the 
heat of the superincumbent lava-bed at the time of deposit. 

Mr. H. B. Woodward speaks of it as a highly crystalline 
limestone.’ 

In 1894 I had the privilege of visiting Tideswell Dale with 
Sir A. Geikie, and pointing out to him the vesicular rock above 
and below the more compact rock seen in the quarry. He then 
discussed the probability of part of this toadstone being a sill, 
and pointed out two faults, the southernmost of which cuts off this 
toadstone and the subjacent limestones from the limestones which 
are higher in the series and contain two small lava-flows. In his 


1 «Tideswell Dale Quarries, Journ. Derby Arch, & Nat. Hist. Soc. vol. x 
(1888) pp. 1-8. 

2 «Further Notes on Tideswell Dale Quarry,’ bid. pp. 9-15. 

3 «Geol. of Eng]. & Wales,’ 2nd ed. (1887) p. 159. 


Vol. 55.| © +‘FAULTED INLIER IN TIDESWELL DALE. 241 


‘Ancient Volcanoes of Great Britain,’ vol. ii (1897) p. 22, he 
writes :—‘ It appeared to me that the dark, compact, crystalline 
dolerite, which was formerly quarried in the middle of Tideswell 
Dale, may be separated from the vesicular toadstone of that valley, 
which is undoubtedly a true lava-flow, and that it does not always 
occupy the same horizon there, being sometimes below and sometimes 
above the amygdaloid. Where it rests on a band of red clay, the 
latter rock has been made columnar to a depth of 9 feet. Alteration 
of this kind is very rare among the Carboniferous bedded lavas, but 
is by no means infrequent in the case of sills.’ This expression of 
opinion led me to investigate the question carefully, and, though 
I was at first sceptical, further work has convinced me that 
Sir A, Geikie’s explanation is the only correct one. 


II. Description oF THE AREA AND ITS GEOLOGICAL STRUCTURE. 


The area described in the present paper is about a square mile 
in extent. It will be seen from the accompanying map (PI. XIX), 
which was drawn up on the scale of 6 inches to a mile, that the 
greater portion of this area consists of a faulted inlier of Carboni- 
ferous Limestone, with its associated toadstones. North and south 
of this inlier are one or two lava-flows, intercalated with the later 
beds of limestone which lie stratigraphically below the Hammerton 
Hill lava. A distinction has been made on the map between the 
compact dolerite of the inher (the sill or intrusive dolerite) and the 
vesicular lavas above and below it. 

A vesicular toadstone, about 600 feet east of the quarry and 
separated from it by a limestone-escarpment, has not been marked 
on the map. I was able to trace it for only a short distance. 

The evidence for the two faults north and south of the inlier is 
clear. The southern fault crosses the middle road to Tideswell, 
near the point where it makes a sharp bend in order to avoid a 
small gully which runs down into Tideswell Dale. The fault 
passes down the gully, crosses the lower road, and runs up a small 
depression between Hammerton Hill and the marble-quarry. South 
of the gully the limestone-beds dip down the dale towards the 
Wye, and intercalated with them are two small lava-flows, each 
about 15 to 20 feet thick, and separated by 15 feet of limestone. 
A few yards away, north of the gully, are massive limestones 
with disturbed bedding. A ridge of limestone marks the southern 
boundary of the fault, as it is followed in a westerly direction 
towards the uppermost road. Following the fault in an easterly 
direction, the toadstone of Hammerton Hill is brought against the 
beds of limestone, which are on a higher horizon than the toadstone 
of the quarry. ‘The beds in the immediate neighbourhood show 
signs of disturbance. 

The northern fault is distant about 4 mile from the southern. 
On both sides of the valley the igneous rock abuts against the 
limestone-beds higher in the series, and is seen within a few feet 
of them. ‘The limestone north of the fault contains at least one 


Odi. 95, NO. 218, R 


242 MR. H. H. ARNOLD-BEMROSE ON A SILL AND [ May 1899, 


small lava-flow, which may be on the same horizon as one of those 
near the southern fault. 

Minor faults trending roughly east and west are seen in the 
limestone along the middle road nearly opposite the marble-quarry. 
They have a small throw of 3 feet and less, and ye walls of the 
joints have sometimes a slickenside surface. 

The limestone between the middle and lower hcl immediately 
north of the southern fault is broken by fissures. 


Ill. Tur Lavas ann IntrustvE DoLeRitE oF THE LNLIER, 


It will be seen from the map (Pl. XIX) and horizontal section 
(fig. 1, p. 244) that the compact dolerite is sometimes found resting 
on the limestone, and at others is separated from it by clay (not 
shown in the map) or by a varying thickness of vesicular lava. 
This lava is seen resting on the limestone in the gully leading up 
to Meadow Farm, and probably attains its greatest thickness 
there, or a short distance north on the upper portion of the hill on 
the western side of the dale. It is not seen at this point on the 
opposite side, being carried down under the road by a south-easterly 
dip. In the quarry, about 2 feet of it was seen at the base of the 
compact dolerite by the Rev. J. M. Mello and the late Mr. Wilson ;* 
though this I have not seen, owing to its having been covered up 
for several years by débris, from the quarry-workings. Resting 
upon the compact dolerite is a vesicular lava, which can be traced on 
the eastern side of the valley from the northern to the southern 
. fault. 

The lower road to Tideswell passes along the bottom of Tideswell 
Dale. Although the beds near the southern fault show signs of 
disturbance, the limestones seen below the compact dolerite of the 
quarry soon dip nearly due north. As the road ascends the valley, it 
passes successively through higher beds of limestone, enters the 
compact dolerite above them, and continues in it as far as the 
northern fault. The horizontal section (fig. 1, p. 244) was made in 
a direction nearly at right angles to the strike of the beds at the 
western and eastern extremities, close to, and nearly parallel with, 
the small valley which runs up to Meadow Farm. At the western 
end of the section the limestone is seen dipping under the vesicular 
toadstone on the southern slope of the small valley. The compact 
dolerite above it is seen in this valley, and also on the hillside along 
which the section was made. The section crosses the middle and 
lower Tideswell roads at a point about 800 feet north of the 
quarry: the limestone below the dolerite is seen in both roads. It 
dips nearly due north, and the beds in the direction of the line of 
section are almost horizontal. Below the compact dolerite, about 
50 feet of limestone is seen, the upper portion on the eastern side 
of Tideswell Dale being marmorized. The limestones below the 


1 Quart. Journ, Geol. Soe. vol. xxvi (1870) pp. 701-702; Geol. Mag. 1870, 
p. 522. 


Vol. 55. ] FAULTED INLIER IN TIDESWELL DALE. 243 


vesicular toadstone at the eastern end of the section dip nearly due 
east. 

The mass of compact dolerite, therefore, occupies different horizons 
in the java-flow, and must be intrusive. Further evidence of 
intrusion has been obtained by an examination of the limestone- 
beds immediately below the toadstone, on both sides of the valley. 

Some 7 feet below the clay is a well-marked bed of finely- 
laminated limestone, several inches thick. ‘This is easily traced on 
the western side of the valley for a distance of nearly 300 yards 
along the middle road to Tideswell, and is also seen in the marble- 
quarry on the opposite side of the valley. This bed was taken 
as a datum-line, and at various points (marked A to M on the 
section, fig. 2, p. 244) measurements were made of the thickness of 
the limestone and clay above it, and the depth to which marmori- 
zation of the limestone extended. The results were plotted to 
scale on a diagrammatic section, in which all effects of the minor 
faults and of the undulations of the beds were eliminated by 
making the datum-line horizontal. The length along the horizontal 
line gives the position of any place in the section, while the vertical 
distances indicate the thickness of the beds and the extent of 
marmorization. 

The marmorized limestone is generally white, has a translucent 
surface when wet, breaks with a saccharoidal fracture, and is 
easily crushed into a white crystalline powder. 

(1) The thickness of the limestone above the datum-line is 
practically constant, varying from 7 to 73 feet, except for a short 
distance at the southern end (where the rocks are covered with 
soil); and consequently the compact dolerite does not cut across the 
beds of limestone. 

(2) The clay varies in thickness from 7 feet downward, and in 
places is absent altogether. 

(3) Where the non-vesicular and compact dolerite rests upon the 
clay, or upon the limestone, the clay is rendered columnar and the 
limestone is marmorized to a depth down to or below the datum- 
bed. 

(4) Where the toadstone resting upon the limestone or clay is 
vesicular or slaggy, and attains a sufficient thickness, the clay and 
the limestone are not altered. 

(5) The bases of the compact dolerite and of the marmorized 
limestone are approximately parallel. 

These deductions point to the conclusion that the metamorphic 
effect is due to the compact dolerite, and not to the vesicular rock. 

This varying amount of metamorphism, due to varying proximity 
of the intrusive rock to the limestone below it, is seen in other 
parts of the dale. On the southern side of the quarry the limestone 
is unaltered, while on the northern side it is marmorized to a depth 
of several feet, and the compact dolerite is found resting upon it. 
The marmorization may be traced from the quarry on the eastern 
slope as far as the cottages north of the quarry. Near Meadow 
Farm, where there is a great thickness of the vesicular rock beneath 

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Vol. 55.] A SILL AND FAULTED INLIER IN TIDESWELL DALE. 245 


the intrusive dolerite, the limestone under it is not marmorized, 
and there is no deposit of clay. 

I have been unable to find any alteration in the limestone which 
lies above these igneous rocks. ‘his is probably due to the fact 
that the intrusive rock made its way among the lower portions of 
the lava, and that the superincumbent limestones were protected 
by the greater thickness of lava between them and the sill. The 
vesicular rock resting upon the intrusive dolerite is seen on the hill- 
side some distance above the quarry, and can be traced from near the 
southern fault, where it is at least 10 to 20 feet thick, to the northern 
fault, where it attains a still greater thickness. 

The vesicular rocks immediately above and below the sill are 
sometimes very hard: this may be due to the heating effects of 
the intrusive dolerite. 


Near the northern fault, on the western side of the valley, is a 
small patch of tuff. It can be traced for a vertical distance of about 
20 feet, and about the same distance horizontally. It is not a 
banded tuff, but in places there are signs of a very rough bedding 
dipping 50° northward. It may be traced to within a few feet of 
the limestone-escarpment which bounds the fault on the north, 
being separated from it by a slight depression in the ground, about 
2 feet deep. It is much harder than the bedded ashes of the district, 
and may either represent a small deposit of tuff bedded with the 
upper part of the lava-flow, and indurated by the sill; or it may be 
a portion of a small neck of agglomerate, which has been faulted 
against the limestone. At present, the evidence seems to me in-° 
sufficient for arriving at a definite conclusion. 


IV. PrerrogrRapuHy. 


(a) The Intrusive Dolerite or Sill. 


The compact dolerite in the quarry was described by Mr. Teall 
as ‘an olivine-dolerite which shows in certain parts the ophitic type 
of structure, in others the type with granular augites. Indications 
of fluxion-structure may be seen in the latter.’! 

Eighteen thin slices of the compact dolerite from various parts of 
the mass were examined by me. In addition to the types described 
by Mr. Teall, is one in which the felspars largely predominate over 
the other minerals: they are present in two generations, and attain 
a length of 2°5 mm. 

Specimens were obtained from the quarry-face at different heights 
in an almost vertical line, so as to ascertain what variation of structure 
occurred :— 


No. 710.—In a specimen a few feet above the top of the 
quarry (sp. gr. 2°80) the felspars form by far the greater 
portion of the rock. They occur in two generations, the 


* «Brit. Petrogr.’ 1888, p. 210 & pl. ix, figs. 1 & 2. 


246 MR. H. H. ARNOLD-BEMROSE ON A SILL AND [ May 1899, 


largest crystals attaining a length of 2mm. The augite is 
in grains. The olivine is altered to the Potluck pseudo- 
morph, sections at right angles to the optic axis giving a 
black cross and negative double refraction in convergent 
light. Rods of magnetite are present. 

No. 8SS.—A specimen from the top of the quarry (sp. gr. 2°83) 
is a typical ophitic olivine-dolerite, in which the felspars are 
generally small. The pseudomorphs of olivine are serpen- 
tinous or of the Peak Forest type.” The magnetite sometimes 
is penetrated by one or more felspars. (Pl. XX, fig. 1.) 

No. 8S9.—A few feet farther down (sp. gr. 2°80) the augite- 
plates, which are sometimes twinned, become smaller, and 
the felspars larger. Potluck pseudomorphs of olivine are 
present. 

No. 587.—About 14 feet below the top of the quarry (sp. gr. 
2°84). The augite is in small grains, or in nests or groups of 
large interlocking grains, and penetrated by felspars only in 
very few instances. The felspars sometimes attain a length of 
2 mm., and predominate over the other minerals. The olivine 
is altered to the Potluck pseudomorph. (Pl. XX, fig. 2.) 

No. 596.—17 feet below the top (sp. gr. 2°88). The augite-grains 
and felspars are smaller, and the olivine is altered to ser- 
pentine. 

Nos. 897 & 900.—20 feet below the top (sp. gr. 2°30). The augite 
is in grains and small prisms, is Jess transparent, and has a 
faint reddish-brown colour in ordinary light. The olivine is 
altered to iron-oxide. 

No. &98.—29 feet below the top (sp. gr. 2°83). The rock is 
similar to the preceding. 

No. 899.—31 feet below the top, and probably about 10 feet 
above the limestone. The rock is a fine-grained dolerite 
(sp. gr. 2°86). The felspars are small, and the olivine is 
altered to serpentine and iron-oxide. 


The fine-grained dolerite immediately above the limestone on the 
opposite side of the valley, No. 34 (sp, gr. 2°86), is similar, but the 
olivine, partly altered to serpentine, has often a fresh nucleus, 
(PEXX, fig. 3.) 

Nearly every thin slice of the coarse and fine-grained types of 
this dolerite contained small quantities of a faint blue or yellow 
material, which is blue or brown in polarized light, with vermicular 
stracture; it probably represents altered patches of interstitial 
matter. 

It is impossible to examine the upper part of the sill with the 
same minuteness as the lower portion, which is so well exposed 
in the quarry. The only evidence to be obtained is from the isolated 
blocks which project above the soil, on the hill-slope. Hand- 
specimens from these were compared with those just described. 
The rock becomes less coarse in structure as its upper surface is 


1 Quart. Journ. Geol. Soc. vol. 1 (1894) p. 613. ® bid. p. 614. 


Wolk 55.] FAULTED INLIER IN TIDESWELL DALE. 247 


approached: some feet below its junction with the overlying lavas 
it is similar to the fine-grained dolerite at the bottom of the sill, 
and cannot be distinguished from it in a hand-specimen. 

This part of the sill in which the quarry is worked is about 
60 feet thick. It is covered by 20 to 30 feet of vesicular lava, 
and rests on the 2 feet of vesicular rock seen in the year 1870 
by Mr. Mello, but now covered by débris. The microscopical 
details given above not only show that the rock is coarsely crys- 
talline in the centre, and becomes fine-grained near its upper and 
lower surfaces, but also that the sill may be divided into five bands 
or zones. ‘The central portion near the top of the quarry consists of 
a band of coarsely crystalline, ophitic dolerite at least 6 feet thick, 
and having a specific gravity of 2°80 to 2°83; above and below it are 
bands of the type with granular augites and large felspars, having 
a specific gravity of 2°80 to 2°84. The lower of these bands attains 
a thickness of about 11 feet. Below this is a band of fine-grained 
dolerite about 14 feet thick, and having when fresh a specific 
gravity of 2°85 to 2°88. The uppermost band is a fine-grained 
dolerite, similar to that which constitutes the lowermost band. 

The rock in the quarry is traversed by numerous small veins of 
a mineral which is probably chrysotile. It is of a golden yellow, 
and consists of prisms or bundles of parallel fibres arranged per- 
pendicularly to the walls of the cracks in which it occurs. While 
wet it is soft and easily rubbed into a waxy material between the 
fingers, but when dried becomes tougher and slightly brittle. It 
has a rough cleavage parallel to the longitudinal axes of the fibres. 
Under the microscope it is dichroic, has straight extinction, and the 
minor axis of depolarization coincides with the direction of the fibres. 


(6) The Vesicular Lava above and below the Sill. 


The vesicular rock (sp. gr. 2:24) above and below the intrusive 
dolerite differs from it in microscropic structure and specific gravity. 
None of the minerals are in so fresh a state of preservation. The 
olivines are smaller, and are replaced by various decomposition- 
products. The felspars are turbid and much altered. Sometimes 
there are traces of augite in small, more or less altered grains. 

A specimen from the upper portion on the eastern slope of the 
valley, above the cottages (sp. gr. 2°72), has the appearance of a 
fragmental rock. One part of the slice is made up of separate 
fragments of a highly vesicular rock, containing felspar-laths and 
microlites in a base which has little reaction on polarized light. A 
secondary felspar-like mineral, which is biaxial and sometimes 
twinned, fills the cracks and larger vesicles. This specimen may be 
from the broken upper surface of a lava-flow. (Pl. XX, fig. 4.) 


(c) The Columnar Clay. 


Several thin slices of the columnar clay were examined, and, as 
might be expected, they exhibit no very definite structure under the 
microscope. They are of an uneven reddish-brown colour, with 


248 MR. H. H. ARNOLD-BEMROSE ON A SILL AND _[{ May 1899, 


darker spots scattered throughout, and contain very thin veins, 
strings, and patches of a greenish material which is grey in polarized 
light. A few minute fragments of quartz or felspar are also present, 
but are too small for testing in convergent light. 


(d) The Limestone below the Igneous Rocks. 


The limestone below the dolerite varies in character. In places 
it is mainly composed of bunches of corals; in others it is fine- 
grained and laminated, and in yet others it appears to be an 
aggregate of nodules. 

A specimen of the nodular limestone below the lava opposite the 
quarry is a clastic rock made up of fragments of shells, encrinite- 
stems, and other organisms, and also of irregularly-shaped pieces of 
a dark, previously-consolidated limestone containing encrinite-stems. 
A few small fragments of tuff are probably present in it. A similar 
rock, partially indurated, is found beneath the clay. It is composed 
of more or less rounded fragments of a very fine-grained brown 
limestone without fossils, and of a limestone with shell-fragments 
considerably altered, mingled with small patches or shreds of a 
green material which are isotropic, and probably tuft-fragments. 
The various portions are cemented by crystalline calcite. 

The laminated limestone 6 feet below the clay, which was taken 
for a datum-line (see p. 243), contains foraminifera and a few shell- 
fragments in a matrix consisting partly of finely-crystalline calcite, 
and partly structureless. It is traversed by veins of iron-oxide. 
The same bed, where marmorized, is composed entirely of crystalline 
calcite in minute grains, with no traces of fossils. It is remarkably 
free from impurities, and the lamin of which it is made up average 
about =, inch in thickness. 


(e) The Tuff near the Northern Fault, 


The tuff near the northern fault (see p. 245) consists of lapilliin a 
cement of calcite. The majority of them are crystalline, and many 
are vesicular. ‘The crystalline fragments contain felspar, pseudo- 
morphs of olivine, and probably of augite, ina groundmass, which is 
sometimes opaque with iron-oxide. The larger felspars are twinned, 
and have a fairly sharp outline. The felspars in those fragments 
which have a lighter-coloured groundmass are often skeleton-crystals 
and microlites, and the lath-shaped sections frequently have jagged 
ends passing into microlites. The rock is in a much fresher state of 
preservation than that in which the bedded tufis of the district are 
generally found, and is hard enough for an agglomerate. (Pl. XX, 
fig. 6.) 


(f) The Lava-flows south of the Inlier. 


A specimen from the upper of the two lava-flows, south of the 
inlier, consists of felspars in a base of iron-oxide; they occur in 
lJath-shaped sections, in bundles and plumes of microlites, and in 
skeleton-crystals. Pseudomorphs of olivine and possibly of augite 
are present. (See Pl. XX, fig. 5.) 


coe 


Quart. Journ. Geol. Soc. Vol. LV, 


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Quart. Journ. Geol. Soc. Vol. LY, Pl, XIX, 


Geotocrcat Mav ov Tipeswein Dany AND PHY NEIGHBOURING AREA. 


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QUART. JOURN. GEOL. SOC. VOL. LV, PL. Xx. 


H. A. B., photomicr - Bemrose & Sons, collotyp. 


INTRUSIVE DOLERITE, LAVAS, AND TUFF, FROM TIDESWELL 
DALE (DERBYSHIRE). 


Vol. 55.] FAULTED INLIER IN TIDESWELL DALE. 249 


Specimens from the lower lava-flow contain two generations of 
felspars, small pseudomorphs of olivine, and small crystals of a 
slightly dichroic mineral which may be a pseudomorph of olivine. 


V. SummMARY AND CoNnCLUSIONS. 


The toadstone of Tideswell Dale consists of lava-flows, between 
which a sill has been intruded. This sill, which is from 60 to 70 
feet thick, cuts across the lower portions of the lava, and sometimes 
reaches the limestone below, but never approaches near enough to 
the limestones above the lava to metamorphose them. The extent 
of alteration of the subjacent limestone and the clay in any place 
depends mainly upon the proximity of the sill to them. 

The alternative explanation, namely, that the whole mass is a 
lava-flow, has for many years been accepted as correct. Against this, 
it has been urged by Sir A. Geikie that such alteration of the 
underlying rocks is rare in the case of lava-streams, but frequent in 
the case of sills, and I may add that in no case of an undoubted 
lava-stream in the county have I been able to find any marmorization 
of the underlying limestone. The structure of the compact dolerite 
or sill is essentially different from that of the lava above and below 
it, and it has a greater specific gravity. Its hardness, absence of 
vesicles, and coarse ophitic structure, passing gradually into almost 
a basaltic rock, are characteristic of an intrusive mass. In a lava- 
flow, however compact the central portions might be, we should 
expect to find the slaggy under-surface continuous, but not inter- 
rupted suddenly, and its place taken by the compact portion, as is 
the case in Tideswell Dale. 

At some time posterior to the intrusion of the dolerite among 
the lavas, the area between the two faults has been uplifted, and 
later still the valley of Tideswell Dale has been eroded through the 
igneous rocks, and through the limestones above and below them. 


EXPLANATION OF PLATES XIX & XX. 
Puate XIX. 


Geological map of Tideswell Dale and the neighbouring area, on the scale 
of 6 inches to the mile. 


PuaTE XX. 


[The figures were photographed by the author under the microscope in 
ordinary light, and enlarged 50 diameters. | 


Fig. 1. Ophitic olivine-dolerite from the top of the marble-quarry which is 
about the centre of the sill. Slide No. 888. (See p. 246.) 
2. Olivine-dolerite, with large felspars and granular augite, 14 feet below 

the top of the quarry. Slide No. 887. (See p. 246.) 

. Fine grained olivine-dolerite near the bottom of the sill. Slide No. 34. 
(See p. 246.) 

. Olivine-dolerite from the lava-flow at the top of the sill. (See p. 247.) 

. Olivine-dolerite from the uppermost of the two lava-flows south of the 
inlier. (See p. 248.) , 

. Tuff near the northern fault. (See p. 248.) 


Oo oF & 


250 A SILL AND FAULTED INLIER IN TIDESWELL DALE. [May 1899, 


DiscussIon. 


Mr. Srrawan regretted that he had never himself visited the spot. 
He enquired whether this was not the first recorded instance of an 
intrusive igneous rock in Derbyshire, and congratulated the Author 
on this addition to his valuable work in that county. The alteration 
of the rocks below the intrusive sill was such as might have been 
effected by a contemporaneous lava-flow ; he had not clearly under- 
stood to what extent alteration had been observed in the overlying 
strata also. It was curious that the dolerite had so closely con- 
cealed itself between sheets of toadstone, and he hoped that further 
search on the part of the Author might reveal other occurrences. 

Mr. R.S. Hurriss also spoke. 

The AvtHor replied to Mr. Strahan that the first recorded sill 
in Derbyshire was. mentioned by Sir A. Geikie in his ‘ Ancient 
Volcanoes of Great Britain.’ The limestone above the sill at Peak 
Forest is marmorized, but not to so great a distance as the lme- 
stone lying below the sill in Tideswell Dale. In the latter place, 
the bed of lava above the sill has probably prevented the lime- 
stones on the top of it from being altered. 


Vol. 55.] ECTOMARIA AND HORMOTOMA. 251 


17. Remarxs on the Gennra Hcromwarra, Koxen, and Horuorom, 
Satter, with Descriptions of British Sencies. By Miss Jaye 
Donatp. (Communicated by J. G. Gooncurip, Esq., F.GS. 
Read February 22nd, 1899.) 


[Puares XXI & XXIT_] 


INTRODUCTION. 


In my previous papers on the Carboniferous Murchisonie I have 
‘given some account of most of the different genera or sections into 
which the family Murchisoniide has been divided. It is not, 
therefore, necessary to refer to many of these again, as I am here 
only describing the British members of one of these established 
genera, namely Hormotoma, Salter,’ and also of the new genus 
Ectomaria, Koken.* 

These two genera contain some of the oldest known species of 
elongated gasteropoda. They are both distinguished from the typical 
Murchisonie by merely possessing a sinus in the outer lip, instead 
of having a deep narrow slit with parallel edges; also the lines of 
growth retreat towards, and advance from, the sinus more obliquely. 
The protoconch, which throws so important a light upon the 
affinities of the gasteropoda, is so far unknown in Ectomaria and 
Hormotoima, neither has it been found out whether these shells have 
opercula. 

In the present state of our knowledge it is doubtful in what 
degree these genera are related either one to another, or to the typical 
Murchisonie.  Hormotoma agrees with Murchisonia therein that 
the sinus gives rise to a band, though it is generally somewhat 
indistinctly limited; whereas Hcetomaria can hardly be said to possess 
a band, the greatest sinuosity of the lines of growth being merely 
situated between two keels. Koken does not place Kctomaria in 
the Murchisoniide, and it is not clear to which family he would 
refer it; apparently it stands in the Raphistomide,*? though he 
states that it, Wurchisonea, and Lowonema are closely allied, and he 
also says that Hctomaria reminds one of certain Glauconie and 
Turritellide. Ulrich & Scofield consider that Solenospira (which 
is most prebably identical with Hctomaria) may be an early repre- 
sentative of the Turritellide, and it certainly bears a strong 
resemblance to some members of that family. They inelude it, 
however, in the Pleurotomariidz, in which family they also place 
many other elongated forms that have a sinus or slit in the outer lip. 
I prefer to follow Koken in separating the elongated shells from 
the shorter Pleurotomarie, and letting them constitute the family 


1 Geol. Surv. Can. ‘Canad. Organ. Rem.’ dec. i (1859) p. 18. 

2 «Die Leitfossilien,’ 1896, p. 395. 

3 «Die Gastrop. des Balt. Untersilurs,’ Bull. Acad. Imp. Sci. St. Petersb. 
ser. 5, vol. vii (1897) no. 2, p. 201. 


252 MISS JANE DONALD ON THE GENERA (May 1899, 


Murchisoniide. In the meantime, I would place both Hormotoma 
and Ectomaria provisionally in this family, awaiting the results of 
further research which may throw more definite light both upon 
the affinities and limits of these groups. 

I desire here to offer my most sincere thanks to all who have 
rendered me assistance. For the loan of specimens I am deeply 
indebted to Mrs. Gray (Edinburgh), the Council of the Geological 
Society, the Geological Survey of Scotland, Prof. Hughes, Prof. 
Sollas, Prof. Lindstrom, M. and Mme. Céhlert, and Mr. Whiteaves ; 
while Messrs. R. Etheridge, E. T. Newton, R. B. Newton, A. 8. Wood- 
ward, H. A. Allen, Fortey (Ludlow), and Madeley (Dudley), and 
Herr Rau (Assistant to Prof. Koken) have helped me either by 
drawing my attention to collections, or by giving me every facility 
for studying those under their charge. I am greatly obliged to 
Mr. McHenry for information concerning Irish localities and hori- 
zons, and to Mr. Goodchild for revising this paper. 


Family Murchisoniide, Koken. 


Genus Ecromarta, Koken. 


Ectomaria, EK. Koken, 1896, ‘ Die Leitfossilien,’ p. 395; 1897, ‘ Die Gastrop. des 
Balt. Untersilurs,’ Bull. Acad. Imp. Sci. St. Petersb. ser. 5, vol. vii, no. 2, p. 201. 

Solenospira, KE. O. Ulrich & W. H. Scofield, 1897, Final Rep. Geol. & Nat. Hist. 
Surv. Minn. vol. iti, pt. ii (Paleont.) p. 959; J. F. Whiteaves, 1897, Geol. Surv. Can. 
‘Pal. Foss.’ vol. iti, pt. iii, p. 193. 


Murchisonia (pars) F. Schmidt, 1858, Archiv Naturk. Liv-, Ehst- u. Kurlands, 
ser. 1, vol. 11, p. 202. 

EHunema? (pars) J. W. Salter, 1859, Geol. Surv. Can. ‘Canad. Organic Rem.’ 
dec. i, p. 30; KH. Billings, 1859, Can. Nat. & Geol. vol. iv, p. 360. 


ea (pars) HK. Billings, 1865, Geol. Surv. Can. ‘ Pal. Foss.’ vol. i, pp. 231 


EHunema (?) J. J. Bigsby, 1868, ‘Thes. Sil.’ p. 153; (pars) S. A. Miller, 1889, 
‘N. Amer. Geol. & Palexont.’ p. 403. 


Murchisonia ? (Hunema ?) R. P. Whitfield, 1882, ‘Geol. Wisconsin,’ vol. iv, pt. iii 
(Paleont.) p. 218. 


Description.—Shell elongated, turreted. Whorls numerous, 
ornamented by spiral keels. ‘The lines of growth slope obliquely 
backward and then forward, forming a broad but shallow tongue- 
shaped sinus, situate between two keels near or below the middle 
of the whorl. Aperture broadly channelled below. 

Dimensions.—The length ranges from about 30 up to 75, or 
even to 100 mm. if MW. Missisquoz, Billings, belong to this genus. 

Remarks.—This genus was first defined by Koken in ‘ Die 
Leitfossilien,’ p. 395, and was afterwards more fully described by 
him in ‘ Die Gastropoden des Baltischen Untersilurs,’ p. 201. He 
gives Murchisonia MNieszkowskii, Schmidt, as the type. I can 
discern no essential difference between the characters of this genus 
and those of the genus Solenospira, founded by Ulrich & Scofield 
for the reception of Hunema(?) pagoda, Salter. I have examined 
Koken’s type-specimens, and have also seen examples which appear 
to be identical with #. (?) pagoda, Salt., in the British Museum (Nat. 
Hist.) from Allumette Island. The lines of growth on the latter 


~ 


Tol. 25 53] ECTOMARIA AND HORMOTOMA. 253 


are very indistinct, but on one individual they may be discerned on 
the lower part of a whorl, where they agree with those of Ulrich 
& Scofield’s figure, op. supra cit. pl. Ixx, fig. 56, which evidently 
is more perfectly preserved. 

E. Nieszkowsku greatly resembles E. (?) pagoda in general form, 
ornamentation, and in the lines of growth; but the latter species 
is smaller and more slender. As Koken’s name has the priority, it 
must stand. The only other species which he describes is Z. kir- 
naensis: it has more evenly convex whorls and less prominent 
ornamentation than the type. 

Resemblances.—HEctomaria may be distinguished from Hormo- 
toma by its possession of a shallower sinus which does not give rise 
to a distinct band, and by the circumstance that its whorls are 
ornamented by more prominent keels. It comes nearest to Hyper- 
gonia, but in that section the sinus is situated above, instead of 
on the widest part of the whorl. In Aclisoides the sinus is deeper, 
and the whorls are more evenly convex. 

Range.—In the British Isles at present I only know of four 
forms which probably belong to this genus: namely, EL. pagoda 
vars. Peachii and orientalis, E. girvanensis, and EH. exigua. 

M‘Coy (‘ Brit. Pal. Foss.’ p. 292) refers a shell from the Lower 
Bala of Knockdollian, near Ballantrae, to Murchisonia angustata, 
Hall. The fossil is much worn and too imperfect for accurate 
‘determination ; but, so far as can be judged, it appears to have more 
in common with members of this genus than with Hormotoma 
angustata, Hall, which Ulrich & Scofield consider to be a variety 
of H. gracilis, Hall. M‘Coy’s specimen gives evidence of two 
rather strong keels on the lower half of each whorl. 

These are all from the Cambrian and Ordovician rocks of Scotland. 
So far, I have not met with any well-authenticated species from a 
higher horizon. 

As already mentioned, Zctomaria occurs in the Ordovician rocks 
of the Baltic Provinces, where it is represented by two species, 
according to Koken. 

In Canada there are Hunema prisca, Billings, from the Calci- 
ferous Group,’ and Hunema (7?) pagoda, Salter, from the Black River 
Limestone, both of which have also been described by Ulrich & 
Scofield from the Stones River Group; the former at Minneapolis 
(Minn.), Dixon (Ill.), and Murfreesboro (Tenn.); the latter near 
Cannon Falls (Minn.), and near Beloit (Wisc.). Whitfield refers 
a shell from the Trenton Group of Wisconsin to Z#. (?) pagoda, 
but Ulrich & Scofield consider it identical with LZ. prisca. 
Whiteaves describes a form from the Galena and Trenton formation 
of Lake Winnipeg, which he states is a variety of Solenospira 
pagoda, Salt., and designates it occidentalis. Murchisonia Adelina, 
Billings, from the Quebec Group of Canada, also probably belongs 


1 The Calciferous Group is by some regarded as Upper Cambrian, and by 
others as Lower Ordovician; the Stones River, Black River, Trenton, and 
Quebec Groups belong to the Ordovician, the Hamilton to the Middle Devonian, 
and the St. Louis to the Lower Carboniferous System. 


254 MISS JANE DONALD ON THE GENERA [May 1899, » 


to this genus; and, as Billings says that M. Misstsquoi from 
the same formation greatly resembles it, perhaps it should be 
referred here. But the species is not figured, and neither it nor 
M, Adelina shows the lines of growth; therefore we can only be 
guided by the general form of the shell, which appears to agree with 
that of members of Hctomarta. Ulrich & Scofield refer several 
species to Solenospira from the Hamilton and St. Louis Groups of 
America, and also from the Devonian and Carboniferous of Europe. 
Some of the latter, they state, having more than four revolving 
keels, may belong to Aclisina. In this surmise they are certainly 
correct in one instance (MW. tenuis, De Kon.), but the other Carboni- 
ferous species mentioned belong to different genera. 


Ecromarta PAGopA (Salt.) var. Peacuir nov. (Pl. XXI, figs. 1 & 2.) 


Description.—Shell elongated and turreted. Whorls angular, 
more than eight in number, wide in proportion to the height. Orna- 
mentation consisting of a strong keel near the middle of the whorl, 
with another equally strong about midway between it and the suture ; 
there is also a slighter keel above, immediately below the suture, 
and an additional keel below on the body-whorl. The uppermost 
space is the widest, and the other two spaces are nearly equal, the 
lowest being but slightly narrower than that next above. Lines of 
growth indistinct, apparently sloping backward to the middle space 
and forward again below. Aperture imperfectly knowu. 

Remarks and Resemblances.—Some shells in the Geological 
Survey Collection, Edinburgh Museum, resemble Hunema (?) pagoda, 
Salt. so closely that I consider it better to regard them as a variety 
of that species, rather than as constituting a distinct species. I 
designate this variety Peachw after its discoverer. It agrees with 
the type in having angular whorls, ornamented by the same number 
of keels, but it differs in having the lowest space narrower than 
that of Salter’s figure, and the whorls are also rather wider in 
proportion to the height. 

In the British Museum (Nat. Hist.) there is a piece of rock 
(No. G. 11489) from Allumette Island, River Ottawa, on which 
there is one fairly good specimen of a keeled shell, and also frag- 
ments of two others which accord very nearly with NSalter’s figure 
and description of H. pagoda. Associated with them there is also 
a smooth shell similar to Hormotoma gracilis, Salt. ‘These fossils 
were originally presented to the Museum of Fractical Geology, 
London, by Sir W. Logan, but were transferred to the British 
Museum in 1880. The type-specimens described by Salter as 
E. pagoda and H. gracilis were collected by Sir W. Logan at Pau- 
quettes Rapids, at the eastern end of Allumette Island. The keeled 
shells in the Museum vary slightly from Salter’s type, as figured, in 
having the lowest space about equal with, mstead of wider than 
that above; in this character they are intermediate between the 
type and the Scottish examples. They, the typical £. pagoda, and 


1 Geol. Surv. Can. ‘Canad. Organ. Rem.’ dec. 1 (1859) p. 30 & pl. vi, fig. 5, 


Wol. 55. | ECTOMARIA AND HORMOTOMA. 255 


the varieties Peachii, orientalis, and occidentalis, are probably merely 
variations of one common form. Lunema prisca of Billings,’ as 
described by him and also by Ulrich & Scofield, appears to be 
another but more slender variety of the same type in which the 
uppermost keel is absent. The variety Peachii greatly resembles 
M. Adelina, Billings,’ in the style of the ornamentation, but that 
species attains a much greater size and has a smaller spiral angle. 
The lines of growth are not well preserved, but where seen on the 
varieties Peachii, orientalis, and the form in the British Museum, 
they accord with those characteristic of the genus Hctomaria. 

Dimensions.—There are four examples of this variety in the 
Edinburgh Museum, which are all more or less imperfect and 
weathered. That figured (Pl. XXI, fig. 1) is distorted obliquely, 
the apex is broken, and only five and a quarter whorls remain, 
whose length =13 mm., width =64 mm. A fragment of a larger 
specimen consists of three whorls, measuring 93 mm. in length, and 
74 mm. in width (Pl. XXI, fig. 2). 

Locality and Horizon.—Durness Limestone, Sutherland, 
which is regarded as either Upper Cambrian wholly or in part, or 
else Lower Ordovician. 


Ecromarra pacopa (Salt.) var. onIENTALIS noy. (Pl. XXI, figs. 3 & 4.) 


Description.—Shell very elongated, turreted. Whorls numbering 
more than nine, increasing gradually, wide. Ornamentation consist- 
ing of two strong, slightly crenulated keels, the strongest of which 
is situated near the middle of the whorls of the spire, and slightly 
above the middle of the body-whorl, the other is a little distance 
below, and is not quite so prominent; there is a very fine thread 
immediately below the suture, and also an additional strong keel on 
the body-whorl. The spaces between the keels are somewhat con- 
cave ; the uppermost is the widest, and the lowermost the narrowest. 
Lines of growth indistinct, apparently sloping backward to and 
forward from the space between the two strong keels. Sutures deep. 
Aperture subquadrate, slightly channelled below. 

Remarks and Resemblances.—This appears to be an even 
more decided variety of H. pagoda than the var. Peachit. The form 
is more slender, the whorls are rather higher, the central keel stron ger, 
the space between it and the keel below wider, and the lowest space 
narrower. It comes very near the variety called occidentalis by 
Whiteaves,* as he states that his shell has a proportionately broader 
slit-band, but his specimen is of much greater size than any of the 
Scottish examples that I have seen, and, as he does not figure the 
shell, it is impossible to ascertain whether it agrees in other 
particulars. 

Dimensions.—There are about ten specimens of this form in 
the Geological Survey Collection, Edinburgh Museum. That figured 
in Pl. XXI, fig. 3, has the apex broken, and only six whorls remain, 


1 Can. Nat. & Geol. vol. iv (1859) p. 360 & fig. 87. 
2 Geol. Surv. Can. ‘ Pal. Foss.’ vol. i (1865) p. 231 & fig. 217. 
3 bid. vol. iii, pt. ii (1897) p. 193. 


256 MISS JANE DONALD ON THE GENERA [May 1899, 


whose length =253 mm., width=9} mm. A larger but more 

weathered specimen, which also has the apex broken, leaving nine 

whorls, measures 33 mm. in length and 10 mm. in width. 
Locality and Horizon.—Durness Limestone, Sutherland. 


EcroMARIA GIRVANENSIS, Sp. nov. (Pl. XXI, fig. 5.) 


Description.—Shell elongated, turreted, composed of more than 
seven gradually increasing whorls. Ornamentation consisting of 
two strong keels, the uppermost of which is situated near the middle 
of the whorl and the other below, a short distance above the suture. 
On the body-whorl there is an additional keel below, and there is 
also a fine thread above at the suture. The two middle keels are 
about equal in strength; the space above them is the widest, and 
that below is the narrowest. Lines of growth very indistinct, 
apparently sloping backward above the strong keels. Aperture 
unknown. 

Remarks.—In Mrs. Gray’s collection, Edinburgh, there is one 
large specimen of this species and a fragment of a smaller specimen 
which is most probably identical with it. The surface of the former 
is much worn, and the latter is merely an internal mould. 

Resemblances.—This species resembles H. pagoda and its 
varieties, but 1s distinguished from them all by being a larger and 
more solid-looking shell. From the type of £. pagoda it further 
differs in the spaces between the keels, being of more unequal 
width, though it agrees with this form in the keels being about 
equal in strength, whereas in the var. orientalis the central keel is 
much the strongest. The character of the ornamentation approaches 
most nearly that of Murchisona Adelina, Billings, but that shell 
increases more slowly and is of greater size. 

Dimensions.—Ihe specimen figured here (Pl. XXT, fig. 5) 
is embedded in the matrix, and shows only the seven lower whorls ; 
these measure 30 mm. in length and 10 mm. in width. 

Locality and Horizon.—In rocks of Llandeilo [Lapworth] 
age at Minuntion (Ayrshire). 


Ecromarta (?) ExiIeva, sp. nov. (Pl. XXI, fig. 6.) 


Description.—Shell small, slender, turreted. Whorls more than 
four, high in proportion to the width, increasing very gradually. 
Ornamentation consisting of two strong keels, the uppermost of 
which is situated near the middle of the whorl, and the other alittle 
below ; there is also a fine thread on the body-whorl which is visible 
immediately above the lower suture on the penultimate whorl. The 
surface of the whorl is slightly adpressed at the suture. Lines of 
growth and aperture unknown. 

Remarks.—There is but one specimen of this species in the 
collection of Mrs. Gray, and itis very imperfect. I therefore refer it 
with some hesitation to this genus, to members of which it bears 
considerable resemblance ; nevertheless, better preserved examples 
may prove it to havea slit in the outer lip, in which case it would 
have to be referred to Murchisonia. 


eVol. 55. | ECTOMARIA AND HORMOTOMA. 257 


Resemblances.—It most nearly resembles Z. prisca, Billings, 
but is much smaller; the whorls are higher, and the two strong 
keels are nearer the middle of the whorl. From £. pagoda, the 
British varieties Peachit and orientalis, and #. girvanensis, it is 
distinguished at once by its much smaller size and by its more slender 
form. 

Dimensions.—The fragment, consisting of about four whorls, 
is embedded in the matrix, and measures 64 mm. in length, the 
_ width of the penultimate whorl being 24 mm. 

Locality and Horizon.—In rocks of Llandeilo [Lapworth] 
age at Minuntion (Ayrshire). 


Genus Hormoroma, Salter, emend. 


Hormotoma, J. W. Salter, 1859, Geol. Surv. Can. ‘Canad. Organ. Rem.’ dee. i, 
p. 18 (Section 2 of Murchisonia). 

[The full synonymy is given separately with the descriptions of the different 
species. | 

Description.—thell elongated, composed of numerous bead-like, 
convex or subangular whorls, which are more or less smooth, being 
devoid of prominent ornamentation. Aperture subovate, narrow 
and produced below. Outer lip having a deep V-shaped sinus, which 
gives rise to a band on all the whorls. This band is flat or slightly 
concave, rarely somewhat raised, being generally more or less level 
with the surface of the whorl, and is margined by a slight thread on 
each side, or else it is merely defined by the lines of growth, its 
limitation being frequently indistinct. The lines of growth curve 
very obliquely back to the band above, and still more strongly for- 
ward below. Inner lip reflected on the body-whorl, and sometimes 
covering a minute umbilicus. 

Dimensions.—The length varies from about 20 up to 200 mm. 

Remarks.—this group of shells was separated from the typical 
Murchisonie by Salter, on account of its having convex bead-like 
whorls, and he gives M. gracilis, Hall, from Pauquettes Rapids, as 
the type. Ulrich & Scofield* have since shown that Salter’s shell 
is distinct from that of Hall, and they designate it H. Salter. Salter 
states that the aperture is rounded, instead of being produced and 
effuse below as in Murchisonia ; but this is not really the case, as 
may be seen by referring to Ulrich & Scofield’s description and 
figures * (op. cit. p. 1016 & pl. lxx, figs. 44-51) or to some specimens 
(G. 11490) from Allumette Island, in the British Museum (Nat. 
Hist.), which in other respects agree with the description and figure 
of H. Saltert (gracilis) as given by Salter. His specimen was 
evidently imperfect, and does not show the prolongation of the aper- 
ture, though the reflection of the inner lip is preserved. The most 
distinctive features of Hormotoma, besides the bead-like whorls, are 
the very oblique direction of the lines of growth, which indicate that 


1 Final Rep. Geol. & Nat. Hist. Surv. Minn. vol. iii, pt. ii (1897) p. 1016. 

? The figures of some of the varieties of H. gracilis, Hall, as represented by 
Ulrich & Scofield (op. cit. pl. Ixx, figs. 20, 26, 31 & 36) show the characteristic 
elongation of the aperture better than the figures of H. Salteri. 


@. J.G.S8. No. 218: ae 


258 MISS JANE DONALD ON THE GENERA [May 1899, 


the outer lp retreated greatly towards and advanced still more 
strongly from the sinus, and also the possession of a sinus shallower 
than that of the typical Murchisonie, which have a slit bordered 
by parallel edges, ‘The surface of the whorls is smooth or merely 
ornamented by fine threads, with the exception of the frequent 
occurrence of a very strong thread or swelling immediately below 
the suture. The position of the band varies in different species, 
being near the middle of the whorl in the type, but considerably 
below it in H. antiqua and H, cingulata, His., while in others it is 
intermediate in situation. 

Ulrich & Scofield consider the characteristics so distinctive as to 
mark out Hurmotoma as a separate genus, instead of merely a section 
of Murchisonia, and I think it advisable to follow them in this 
matter. 

Resemblances.—In general appearance this genus most nearly 
approaches Celocaulus, Cihl.,* from which it is distinguished by 
its less elongated form, more convex whorls, deeper sinus, more 
strongly retreating and advancing lines of growth, and aperture of 
different shape. It also bears some resemblance to A clisordes, Don.,” but 
differs in having more oblique lines of growth, a very slightly defined 
band, and in the ornamentation, when pr esent, not consisting of such 
strong raised threads and keels. Ulrich & Scofield believe ‘that the 
relationship of Hormotoma lies between Plethospira, U.& Se. (type Ho- 
lopea cassina Whitf.), and Turritospira, U.& Se. (? Turritoma, U.&8e.). 
On p. 1018 (op. cit.) Ulrich & Scofield speak of Hormotoma being 
related to Turritospira, Ulr., though they do not appear to describe a 
genus under that name, but under Turritoma (p. 959), which genus 
they also state is related to Hormotoma. Are the two names intended 
to designate the same genus? and if so, which is to stand? 
M. acrea, Billings, is given as the type of Yurritoma, and it 
certainly seems unfortunate that the above-mentioned authors have 
chosen as type of a new genus a species in which none of the surface- 
markings are represented or described. From Plethospira it is 
distinguished by having a deeper sinus in the outer lip, and in being 
more elongated. In Yurritoma the contour of the whorl is different, 
being flatter or slightly convexo-concave above and prominent below, 
where the band is situated ; the character of the lines of growth is 
not indicated. 

Range.—lIn the British Isles this genus is known first to occur in 
strata referred either to the Upper Cambrian, or else to rocks near 
the base of the Ordovician, and it continues from this horizon upwards 
throughout the Silurian. The earliest British forms occur in the 
Durness Limestone, and the latest in the Upper Ludlow Rocks. I 
am not acquainted with any Devorian or Carboniferous representa- 
tives in the British Isles. Salter, in his ‘ Catal. Cambr. & Silur. 


1 Tam greatly indebted to M. and Mme. Géthlert for lending me C Davidsoni 
(figured in Bull. Soc. Etudes sci. Angers, 1887, p. 20 & pl. vii, figs. 4—4d), 
the type of the genus, and I was thus enabled to compare it with members of 
Hormotoma. 


2 Quart. Journ. Geol. Soc. vol. liv (1898) p. 66. 


Vol. 55.] ECTOMARIA AND HORMOTOMA. 259 


Foss. Cambridge Museum,’ records eight species of Hormotoma, 
namely, M. articulata, Sow., M. angustata, Hall, MW. cingulata, His., 
M. torquata, M‘Coy, and four forms which he does not name. 
Of these M. articulata and M. cingulata are the only species 
which can be placed in this genus. The specimen referred to as 
M. angustata is a very poor cast, which,if one may judge by the 
available evidence, appears to have more affinity with the genus 
Ketomaria. In M. torquata the lines of growth are not so oblique, 
and it bears the characters of the true Murchisonice, so far as can be 
discerned. It occurs merely as external moulds, and the wax 
impressions taken from them do not show the band very distinctly. 
The others, given on pp. 97 & 155 (op. cit.), are merely casts, only 
one of which exhibits the lines of growth on a portion of the surface, 
and these prove it to have more in common with Loxonema than 
with Hormotoma, as the tongue-shaped sinus is absent. 

Besides the two individuals mentioned above, there are eight 
British Camprian, Ordovician, and Silurian species known to us at 
present, namely, H. Salterr, Ulr. & Sco., A. (2) gracillima, Salt., 
H. (?) dubia, sp. nov., H. (?) Piperi, sp. nov., H. Griffithi, sp. nov., 


AZ, sumilis, sp. nov., H. antiqua, sp. nov., and H. Grayzana, sp. nov., 


making a totaloften. Three, however, are too imperfectly preserved 
to admit of absolute certainty as to the correctness of their reference 
to this genus. 

On the Continent species have been recorded from France, 
Scandinavia, and Russia. In the first-named country D. & P. Gthlert? 
have described two species from the Devonian of Mayenne, namely, 
HI, Lebesconter, Hhl., and H. clavicula, Géhl., and they were so good 
as to send me the former to examine. It differs from the type of 
Hormotoma in having more regularly convex whorls, which are less 
closely coiled and have deeper sutures ; the lines of growth do not 
retreat and advance so strongly, and there are traces of a spiral 
thread in the middle of the band. The other species also has very 
convex whorls which are detached one from the other, and according 
to the figure the lines of growth are much the same as in H. 
Lebesconter. The foregoing considerations show that these species 
can hardly be regarded as members of the genus Hormotomua. 

The latest work on the Scandinavian Silurian gasteropoda is that 
of Lindstrom,’ in which (pp. 126-127) he divides the Murchisonie 


into two groups, namely, Simplices and Ornate. The former group 


contains four species which belong to this genus ; they are MV. cingu- 
lata, His., M. cava, Lind., M. moniliformis, Lind., and MW. subplicata, 
Lind., which all agree in having smooth beaded whorls, with shghtly 
margined band and very oblique lines of growth. The other species 
associated with them by Lindstrom are M. obtusangulata, Lind., 
M. compressa, Lind., M. attenuata, His., and M. paradowa, Lind. 
Ulrich & Scofield include the first-named in Hormotoma, but the 


1 “Deser. qq. Esp. dévon. de la Mayenne,’ Bull. Soc. Etudes sci. Angers, 


1887, pp. 18-19 & pl. vii, figs. 3-3b & 7-7e. 


> *Silur. Gastrop. & Pterup. of Gotland,’ Kongl. Svensk. Vet.-Akad. Handl. 
vol. xix (1884) no. 6. 
s 2 


260 MISS JANE DONALD ON THE GENERA [May 1899, 


whorls appear more angular and the form of the band is different. 
The three latter species are distinguished from Hormotoma by having 
a prominent band, but are evidently closely allied, as the lines of 
growth agree in curving backward and forward very obliquely ; and 
in adult specimens of JZ. attenuata, near the aperture, the lines of 
growth may be traced from suture to suture, passing over the band 
where they are strongly arched, but there is no break as in the typical 
Murchison. It may here be mentioned that Pleurotomaria insignis, 
EKichw.,! though of much greater size than the type of Hormotoma, 
agrees with it in all essential characteristics. The band is usually 
level with, or but slightly depressed below, the surface of the whorl, 
though sometimes in the adult it becomes rather elevated ; the lines of 
srowth, however, continue from suture to suture, as on the rest of 
the shell. There is thus a connecting link between the members of 
Hormotoma that have a flat, slightly margined band, and those forms 
where the band is solid and elevated throughout all the whorls. 
This latter group occurs also in America, and is represented by 
M. Artemisia, Billings,” from the Calciferous Formation. It would 
perhaps be more advisable to class it as a sub-genus of Hormotoma, 
rather than include it in that genus, or regard it as representing a 
distinct genus itself. 

Eichwald records Pleurotomaria insignis, Kichw., Pl. exilis, Kichw., 
Pi. bellicincta, Hall, and Pl. cingulata, His., from the Ordovician and 
Silurian of the Baltic Provinces and the Urals. The first has since 
been more fully described and figured by Koken, who kindly allowed 
me to examine his specimens at 'l'ubingen, and for reasons pee 
given I refer it to the genus under discussion. Koken! considers 
that Pl. evils may possibly be a young example of this species. He 
also states that EKichwald has described several distinct forms as 
Pl. bellicincta, Hall, one of which from Hohenholm is more slender, 
and Koken‘ designates it Evtomaria kirnaensis, while others he 
believes to be allied to Murchisonia Milleri, Hall. One specimen is 
compared with Turbo cirrosus, Sow., by Hichwald. Schmidt’ says 
that the shell from Wesenberg called PL: bellicincta, Hall, by Kichwald 
is perhaps identical with Pl. insignis, Kichw.; Hichwald, however, 
states that it is one half smaller than that. species. He records 
Pl. cingulata, His., from both the Upper Stage of the Urals and the 
Lower Stage of Esthonia. This species is essentially an (Upper) 
Silurian form ; it is, therefore, doubtful whether the shells from the 
latter locality arereally Hisinger’s species. Koken considers them 
distinct and names them M/. Hichwaldi.6 The examples from the 
Urals are much larger: that figured is evidently different from 


= 


‘Leth. Ross.’ vol. i, pt. i1 (1860) p. 1164 & pl. xliii, fig. 1. 
Geol. Surv. Can. ‘ Pal. Foss.’ vol. i (1865) p. 345 & fig. 332. 
3 «Die Gastrop. des Balt. Untersilurs,’ Bull. Acad. Imp. Sci. St. Petersb. 
ser. 5, vol. vii (1897) no. 2, p. 207. 4 Ibid. p. 208. 
‘Untersuch. tiber die Silur. Form. v. Ehstland, Nord-Livland u. Csel,’ 
Aveun Naturk. Liv-, Ehst- u. Kurlands, ser. 1, vol. ii (1858) p. 202. 
b# Weber mdie Entwickelung der Gastropoden vom Cambrium bis zur Trias,’ 
Neues Jahrb. Beilage-Band vi (1889) p. 371. 


to 


Oo 


Wols 55. ECTOMARIA AND HORMOTOMA. 261 


it, and I am uncertain of its having any claim to inclusion in 
Hormotoma. The specimen figured in ‘The Geology of Russia’ 
by Murchison, De Verneuil, & Von Keyserling, vol. 1, p. 339 & 
pl. xxi, fig. 7, from the (Upper) Silurian is also different: the 
authors themselves doubt its identity with the Scandinavian species, 
both on account of its much greater size and its prominent central 
band, and if it should prove distinct they suggest the specific name 
Demidorfi. The form of the band and the less oblique lines of 
growth distinguish it from Hormotoma. Schmidt also gives MM. cin- 
yulata, His., from the Obere Cisel’sche Gruppe (Upper Silurian). 
The Pl. ensigns, Pl. exilis, and Pl. bellicincta of Eichwald are all 
from the Lower Stage (Ordovician ?). Pl. bijugata, Kichw., from 
the Middle Stage, may perhaps belong to Hormotoma, but the figure 
and description are insufficient to determine this point. 

From Offley Island, in the Arctic Regions, a large species has been 
recorded by Mr. R. Etheridge,’ which he has named WM. latifasciata. 
An examination of the type-specimen convinces me that it should be 
referred to Hormotoma, as it has the very oblique lines of growth 
and characteristic band of that species. 

Two species of Hormotoma were given by Bigsby in ‘ Thes. Sul.’ 
p. 156, from the Gordon Isles (Tasmania,) namely, H. ne "1nea, Salt., 
and H. usitata, Salt. The names are only in MS., and the original 
specimens are probably in the Tasmanian Museum, Hobart. They 
were afterwards included in the ‘Catal. Austral. & Tasman. Foss.’ 
by R. Etheridge, Jun., in 1878, and were also given in the lists 
ot Lower Silurian (Ordovician) fossils in the ‘System. Acc. Geol. 
Tasmania, by R. Johnston, in 1888, but Tey were neither described 
nor figured. 

In the United States and Canada there are numerous species of this 
genus. Ulrich & Scofield? refer the following to it:—V/. Anna, Bill., 
M. simulatriv, Bill., M. Vesta, Bill., and M. gracilens, Whitf., from 
the Caleiferous Group ; ; MW. Procri is, Bill., from the Black River Group ; : 
M., gracilis, Hall, H, subangulata, Ulr. eer Salter’, Ulr., M. bellicincta, 
Hall, H. trentonensis, Ulr., and ? M. major, Hall (not M. major, 
Whitt, which they sales identical with H. trentonensis), from the 
Trenton and Cincinnati Groups; and M. Hebe, Bill., from Gaspé. 
They judge it best to place MW. egregia, Bill., from the Gaspé Sandstone, 
here, although they say the band is too low for it to be regarded as a 
typical member of the genus. A consideration of the species described 
in this paper will, however, show that the band varies in position. 
M. agilis, Bill., from the Quebec Group, they also state may belong 
here, but it is insufficiently known. Of MW. teretiformis, Whiteaves, 
they remark that it has all the characters of Hormotoma despite 
its great size, and they believe it to be distinct from the species of 
Billings described under that name. They regard M. anqustata, 
Hall, as a variety of MW. gracilis. 

To the foregoing list must be added H. winnipegensis, Whiteaves,’ 

1 Quart. Journ. Geol. Soc. vol. xxxiv (1878) p. 600 & pl. xxvii, fig. 1. 


2 Final Rep. Geol. & Nat. Hist. Surv. Minn. vol. iii, pt. ii (1897) p. 1014. 
3 Geol. Surv. Can. ‘ Pal. Foss.’ vol. iii; pt. iii (1897) p. 192 & pl. xxi, fig. 1. 


262 MISS JANE DONALD ON THE GENERA [May 1899, 


from the Galena, Trenton, and Black River Formations of Lake 
Winnipeg; it is a very large shell, greatly resembling the European 
Hf. insignis, Kichw. M. melaniaformis, Shumard,' from the Calciferous 
Group, and M. Boydii, Hall,’ from the Guelph Formation, may possibly 
also be referred here, but they are both too imperfect for certainty. 
Ulrich & Scofield place M. Loganzi, Hall, from the Guelph Formation, in 
the genus Calocaulus, but it is not well enough represented to say to 
which genus it should be referred. As figured in ‘ Pal. New York,’ 
vol. 11 (1852) pl. Ixxxiii, fig. 46, by Hall, and in Quart. Journ. 
Geol. Soc. vol. xxxi (1875) pl. xxvi, fig. 8, by Nicholson, it closely 
resembles H. cingulata, His., but fig. 4a of Hall has a greater spiral 
angle. 


Hormoroma Satrert, Ulrich & Scofield. (Pl. XXTI, figs. 7-11.) 


Hormotoma Salteri, E.O. Ulrich & W. H. Scofield, 1897, Final Rep. Geol. & Nat. 
Hist. Surv. Minn. vol. iii, pt. ii (Paleont.) p. 1016 & pl. Ixx, figs. 44-51. 

Murchisonia (Hormotoma) gracilis, J. W. Salter, 1859, Geol. Surv. Can. ‘Canad. 
Organ. Rem.’ dec. i, p. 22 & pl. v, fig. 1 (non MW. gracilis, Hall). 

Description.—Shell elongated, conical, composed of more than 
ten whorls. Whorls increasing at a moderate rate, smooth, flat above, 
convex below, with a slight swelling immediately beneath the 
‘suture. Sinual band situated near the middle of the whorl, flat or 
rather concave, margined by a faint raised thread or obscure keel 
on each side. The lines of growth curve obliquely backward to the 
band above, and still more strongly forward below, indicating a V- 
shaped sinus of moderate depth in the position of the band. Sutures 
deep. Aperture subovoid, produced below and slightly channelled, 
Inner hp reflected on the body-whorl, and possibly covering a minute 
umbilical chink. Columella somewhat thickened and arched for- 
ward. Base convex. 

Remarks.—This species was first described by Salter, and iden- 
tified by him with Murchisonia gracilis, Hall. Ulrich & Scofield 
have since pointed out that it is a larger shell with a greater spiral 
angle, and they therefore separate it from the typical M. gracilis 
under the specific name Salteri. There are two specimens in the 
Geological Survey Collection, Edinburgh Museum, which appear to 
agree with this species. As they are merely casts, one cannot, 
however, be quite certain of their identity. They are sufficiently 
preserved to show some of the distinctive characters, namely, the 
smooth, convex, and subangular whorls with slightly thickened 
sutural margin, subovoid aperture, reflected inner lip, and indica- 
_ tions of the flat submedian band. In the British Museum (Nat. 
Hist.) there are seven specimens of this species from the Trenton 
Group, Allumette Island (G. 11489 and G. 11490), with which I 
have compared the Scottish shells, and I find that they agree with the 
smaller examples. The lines of growth, sinual band, and aperture 
are best preserved on a fragment of the largest Canadian shell, which 
is probably the var. nitida, Ulr.& Sco. It consists of three whorls, 


1 Rep. Geol. Surv. Missouri, 1855, p. 208 & pl. C, fig. 13. 
* «Pal. New York,’ vol. ii (1852) p. 346 & pl. Ixxxiii, fig. 3. 


Vol. 55.1] ECTOMARIA AND HORMOTOMA. 263 


and is figured in Pl. XXJ, figs. 10 & 11; it measures 28 mm. in length 
and 17 mm. in width. 

Dimensions.—tThe largest British specimen has about five 
whorls, the apex being broken; its length =19° mm., width of 
penultimate whorl =87 mm. ‘The smaller shell on the same slab 
consists of little more than four whorls, which measure 143 mm. in 
length and 74 mm. in width. 

Locality and Horizon.—Durness Limestone, Sutherland. 
Salter gives Pauquettes Rapids, River Ottawa; Ulrich & Scofield 
also state the occurrence of the var. canadensis’ in the Black River 
Rocks at the same locality, and say that it is found (more rarely) 
together with the var. tennessensis” in equivalent orsomewhat younger 
strata between Nashville and Lebanon (Tenn.). The typical form 
was obtained in abundance, and the var. nitida® rarely, in the upper 
part of the Trenton Group between Burgin and Danville (Kentucky), 


Hormotoma (?) eracittima (Salter). (Pl. XXI, fig. 12.) 


Murchisonia gracilis, var. gracillima, J. W. Salter, 1859, Quart. Journ. Geol. 
Soc. vol. xv, p. 379 & pl. xiii, figs. 7-8; (pars) R. Etheridge, 1888, ‘ Foss. Brit. Is.’ 
vol. i (Paleozoic) p. 1138. 

Description.—Shell very elongated, composed of more than 
twelve gradually increasing whorls, which are convex, but slightly 
angular near the middle. Surface-ornamentation, band, and aper- 
ture unknown. Imperforate. 

Remarks.—These shells were referred somewhat doubtfully by 
Salter to Murchisonia gracilis, Hall; he observes that they have a 
smaller spiral angle and more numerous whorls, and he suggests the 
name gracillima if these differences should be considered of specific 
value. The only known examples are embedded in the matrix, and 
are so imperfect that it is impossible to make a satisfactory com- 
parison with other species; but, as they certainly appear more 
slender than Hall’s species, I consider it advisable to regard Salter’s 
name as specific instead of merely varietal. 

Dimensions.—There are two specimens in the Museum of Prac- 
tical Geology, London, the largest of which consists of about twelve 
whorls, and is refigured in Pl. XXI, fig. 12. It measures 37 mm. in 
length and 94 mm. in width. The smaller shell has about ten whorls, 
whose lengthis 18 mm. Another example is in the British Museum 
(Nat. Hist.), but it also is merely a section and is not so well | 
preserved as the others; it measures 363 mm. in length. 

Locality and Horizon.—Durness Limestone, Sutherland. 


Hormortoma (?) pusta, sp. nov. (Pl. XXI, fig. 13.) 

Murchisonia bellicincta (?), J. W. Salter, 1859, Quart. Journ. Geol. Soc. vol. xv, 
p. 380 & pl. xiui, fig. 11. 

Description.—Shell elongated, composed of more than three 
whorls. Whorls flattened, and but slightly convex. Band, orna- 
mentation, and aperture unknown. 


1 This variety has the band on the middle of the whorl. 
2 Band a little above the middle of the whorl. 
° This is of larger size, relatively plump form, and has a wider spiral angle. 


264 MISS JANE DONALD ON THE GENERA [May 1899, 


Remarks and Resemblances.—A much weathered fragment 
of a shell, consisting of portions of three whorls, was referred with a 
query by Salter to Murchisoma bellicincta, Hall. So far as can be 
judged, however, the spiral angle is smaller than that of Hall’s 
species, also the whorls are less convex. Therefore I provisionally 
separate it under the specific name of dubia, and place it in the 
genus Hormotoma until better specimens are discovered, enabling its 
true affinities to be discerned. | 

Dimensions.—The length is 26 mm. and the width 24 mm. 

Locality and Horizon.—Durness Limestone, Sutherland, 


Hormoroma crINeULATA (His.), (Pl. XXT, figs. 14-17.) 


*? Turbinites levis major etc., Bromell, 1738, ‘ Lithogr. Suec.’ in Acta Lit. Suecia, 
vol. iti, p. 37. 

Turritella cingulata, W. Hisinger, 1829, ‘Esquisse d’un Tabl. des Pétr. de la 
Suéde,’ 1st ed. p. 11; 1831, ‘ Anteckn.’ vol. v, p. 115 & pl. ii, fig. 1; ‘Esquisse d’un 
Tabl. des Pétr. de la Suéde,’ 2nd ed. p. 9; 1837, ‘ Leth. Suec.’ p. 39 & pl. xii, fig. 6a. 

Non Pleurotomaria cingulata, L. von Buch, 1840, ‘ Beitr. zur Bestimm. d. Gebirgs- 
form. v. Russland,’ p. 116; *? W. Hisinger, 1841, ‘ Fortekning,’ p. 56. 

Murchisonia cingulata, A. VArchiac & EH. de Verneuil, 1841, Bull. Soc. géol. 
France, vol. xii, p. 159; non Murchison, De Verneuil & Von Keyserling, 1845, 
‘Russia & the Ural Mts.’ vol. ii, p. 339 & pl. xxii, figs. 7a & b; non F. M‘Coy, 1846, 
‘Syn. Silur. Foss. Irel.’ p. 16 & pl. i, fig. 18. 

Terebra (?) sinuosa, J. W. Salter, 1848, Mem. Geol. Surv. vol. 11, pt. i, p. 357 & 
pl. xiv, fig. 2 (non Sowerby, 1839, ‘Sil. Syst.’ p. 619 & pl. viii, fig. 15, wee Phillips, 
1841, ‘ Pal. Foss. Cornw., Dev., & W. Som.’ p. 99 & pl. xxxviii, fig. 182). 

Murchisonia cingulata (pars), H. G. Bronn, 1848, ‘ Index Paleont.’ p. 747; (pars) 
A. d’Orbigny, 1850, ‘ Prodr. Paléont. strat.’ vol. 1, p.381; J. Morris, 1854, Cat. Brit. 
Foss. p. 259; F. M‘Coy, 1855, ‘ Brit. Pal. Foss.’ p. 293; ? F. Schmidt, 1858, Archiv 
Naturk. Liv-, Ehst- u. Kurlands, ser. 1, vol. ii, p. 202. 

Non Pleurotomaria cingulata, Eichwald, 1860, ‘ Leth. Ross.’ vol. 1, pt. ii, p. 1166 & 
pl. xliui, fig. 6. 

Murchisonia cingulata (pars), J. J. Bigsby, 1868, ‘ Thes. Sil.’ p. 158; J. W. Salter, 
1873, Cat. Cambr. & Silur. Foss. p. 172; non F. Roemer, 1876, ‘ Leth. Geogn.’ 
pl. xiv, fig. 11; non A. Krause, 1877, Zeitschr. deutsch. geol. Gesellsch. vol. xxix, 
p- 22; *non Kiesow, 1884, ‘ Ueber Sil. u. Dev. Geschiebe Westpreussens,’ p.. 58; 
G. Lindstrém, 1884, ‘Silur. Gastr. & Pter. Gotland,’ Kong]. Svensk. Vet.-Akad. Handl. 
vol. xix, no. 6, p. 127 & pl. xii, figs. 9-10; (pars) R. Etheridge, 1888, ‘ Foss. Brit. Is.’ 
vol. i (Palzozoic) p. 118. 


Description.—Shell large, very elongated, composed of more 
than eleven gradually increasing whorls. Whorls compactly coiled, 
broad and flat, being very slightly convex. Ornamentation con- 
sisting of numerous fine spiral strie. Sutures shallow. Sinual 
band situated low down on the whorl, level with the surface, or 
rather depressed, defined on each side by a fine raised thread or merely 
by the lines of growth. Lines of growth distinct, strong, irregular in 
strength, curving very obliquely backward to and forward from the 
band. Aperture imperfectly known. Inner lip reflected on the 
body-whorl. Base slightly flattened, having a short distance below 
the band a subangularity, which occasionally shows above the suture 
on some of the higher whorls. ‘Test thin. 

Remarks.—tThe British shell which has been referred to this 
species, though agreeing with Hisinger’s figure and description * in 
other respects, appeared to differ in having a smaller spiral angle; 

* These references are taken from Prof. Lindstrém’s work on the Silur. 
Gastropoda & Pteropoda of Gotland, for I have not been able to see the works 
myself, 


1 «Leth. Suec.’ 1837, p. 39 & pl. xii, fig. 6a. 


Vol. 55.] ECTOMARIA AND HORMOTOMA. 265 


therefore I was not quite satisfied with the correctness of the identi- 
fication. Through the kindness of Prof. Lindstrom, however, I have 
been able to compare the British with Swedish specimens. He lent 
me examples from three different localities in Gotland, namely, 
Gothem, Botvaldavik, and Horsne, which resemble the British shells, 
more especially the example from Gothem, which appears to have a 
slightly smaller spiral angle than those from the other places. 
Hisinger’s original, Prof. Lindstrom states, was ‘found by him ina 
detached stone near the church of Gothem. The rock isa variety of 
oolite peculiar to a quarry at the base of Barabacke, and consequently 
there cannot be any doubt of its being derived from that place” * In 
his letter, when sending me the examples, he writes, ‘There may be 
slight variations as to the dimensions of the whorls, but on comparing 
them with Hisinger’s type I am convinced that they are of the same 
species.’ Thus I have no hesitation in referring the British shell to 
this species. The first notice of its occurrence in England is that 
of Salter,? who mistook it for Terebra(?) sinuosa, Sow., not having 
observed its identity with Hisinger’s species. 7. (?) sinuosa, Sow., 
‘however, is a much smaller shell and its structure is quite distinct, 
there being no sinual band, and the lines of growth are sigmoidal 
as characteristic of Loxonema. M‘Coy was the first to refer an 
example of this form as well as Salter’s specimen to Murchisonia 
cingulata (His.).? But he is at fault in considering an Irish shell 
as a variety of this species,* for it has narrower whorls and the 
sinual band is situated higher up. 

Resemblances.—This species differs from the other members of 
the genus Hormotoma in having less convex whorls, the band situated 
lower down on the whorl, a subangularity on the base, and in having 
the surface covered with fine spiral striz which are reticulated by 
the lines of growth. These spiral striz are visible only on well- 
preserved examples, and the surface of but one of those sent 
from Sweden (that from Botvaldavik) is good enough to show 
traces of them. This shell also shows the lines of growth on the 
sinual band, which I have not observed so clearly on any British 
specimen. In spite of the differences in structure from the type, 
I consider it advisable to place this species in the genus Hormotoma 
for the present, especially as I know of no other genus with which 
it more nearly agrees. In contour it resembles members of Ca@lo- 
caulus, CEhl., but there the sinus in the outer lip is shallower, the 
lines of growth do not sweep backward and forward so obliquely, 
and the umbilicus is deeper. The British species to which it bears 
most likeness is Hormotoma Pipert, but it is distinguished by its 
smaller spiral angle, less convex whorls, and shallower sutures. It 
also resembles H. antiqua in the low position of the band and 
slightly convex whorls, but in that shell the whorls are lower and 
the lines of growth more oblique. Among American species it is 


i] 


‘Silur, Gastr. & Pter. of Gotland, Kongl. Svensk. Vet.-Akad. Handl. 
vol. xix (1884) No. 6, p. 128. 

2 Mem. Geol. Surv. vol. ii, pt. i (1848) p. 857, 

3 ¢ Brit. Pal. Foss.’ 1855, p. 293. 

4 «Syn. Silur. Foss. Irel.’ 1846, p. 16. 


266 MISS JANE DONALD ON THE GENERA [May 1899, 


very like Af. Loganii, Hall, especially as represented in ‘ Pal. New 
York,’ vol. 11 (1852), pl. lxxxiu, fig. 4, and by Nicholson, in Quart. 
Journ. Geol. Soc. vol. xxxi (1875) pl. xxvi, fig. 3: fig. 4a, Hall, 
appears to have a greater spiral angle. None of these figures, 
however, are sufficiently distinct for satisfactory comparison. 
‘Locality and Horizon.—tThis species is fairly abundant in the 
Silurian rocks, but is rarely well preserved. Salter’s type (Pl. XXI, 
fig. 15) was in the collection of the Rev. T. T. Lewis, and is now in 
the British Museum (Nat. Hist.); it comes from the Aymestry Lime- 
stone of Mocktree (Herefordshire). About three and a half whorls 
are preserved, which measure 52 mm. in length and 25 mm. in width. 
The specimen mentioned by M‘Coy is in the Woodwardian Museum, 
Cambridge, and comes from the Aymestry Limestone of Leint- 
wardine (Shropshire). Besides these there are four examples in the 
Piper Collection, British Museum (Nat. Hist.), from the Aymestry 
Limestone of Knapp Lane, Ledbury ; three in the Museum of 
Practical Geology, London, which are all casts and badly preserved, 
from the Lower Jiudlow near Ledbury, and the Aymestry Lime- 
stone of Llanbadock and N.E. Leintwardine respectively; and four 
much-weathered casts in the Ludlow Museum from the Aymestry 
Limestone, for which no locality is given. There are about ten speci- 
mens in the Grindrod Collection, Oxford University Museum, from the 
Lower Ludlow and one from the Upper Ludlow; no localities are 
given, and few of the shells are particularly well preserved ; one 
(Pl. XXI, fig. 16) has the lines of growth very distinct, and another 
shows the spiral striz all over the surface. An individual in the 
Museum of the Geological Society of London, from Aymestry, has the 
surface well preserved, and is figured in Pl. XXI, fig. 14. It consists 
of seven whorls ; both the apex and base are imperfect ; its length 
is 52 mm.,and width 20 mm. Lindstroém gives 63 mm. as the length, 
and 28 mm. as the width. The specimen which he sent me from 
Gothem is the largest; it consists of about eight and a half whorls, and 
has the apex broken. It measures 84 mm.in length, and 28 mm. in 
width. Some of the British examples, if entire, would quite equal 
these in size. The Swedish forms, according to Prof. Lindstrom, 
occur rather high up in the geological series, in the uppermost lime- 
stone, about homotaxial with the Upper Ludlow of Great Britain. 


Hormotoma (?) Preeri, sp. nov. (Pl. XXII, figs. 1 & 2.) 


Description.—Shell elongated, turreted. Whorls more than 
five, increasing at a moderate rate, convex and smooth. Sutures 
deep. Band probably situated below the middle of the whorl. 
Aperture imperfectly known. Umbilicus closed. 

Remarks.—There are four specimens of this species in the 
Piper Collection in the British Museum (Nat. Hist.) ; they are all 
casts, and show no traces of ornamentation or lines of growth. 
One shell bears indications of the sinual band on the body-whorl. 
I place it in Hormotoma, on account of its general resemblance to 
other members of the genus. 

Resemblances.—tThis species resembles most nearly H. cingu- 


Vol. 55.] ECTOMARTIA AND HORMOTOMA, 267 


lata (His.), from which it is distinguished by its more convex whorls, 
greater spiral angle, and also the position of the band, which is 
apparently rather higher. Better preserved specimens may perhaps 
prove it to be a variety of that species, for it is difficult to make a 
satisfactory comparison from casts. All the internal moulds of 
H. cingulata (His.), however, that I have seen have the whorls still 
flatter than in the shell itself. 

Locality and Horizon.—The specimens are all from the 
Aymestry Limestone of Knapp Lane, Ledbury. The largest example 
(Pl. XXII, fig. 2) is slightly compressed; it measures 61 mm. in 
length, and 30 mm. in width. 


Hormoroma GrirritHi, sp.nov. (Pl. XXII, figs. 3-5.) 


nee ona cingulata, ? var., F. M‘Coy, 1846, ‘Syn. Silur. Foss. Irel.’ p. 16 & 
i Na baivetin cingulata, W. Hisinger, 1837, ‘ Leth. Suec.’ p. 39 & pl. xij, fig. 6. 

Non Murchisonia cingulata, F. M‘Coy, 1855, ‘ Brit. Pal. Foss.’ p. 293; (pars) 
J.J. Bigsby, 1868, ‘Thes. Sil.’ p. 158; (pars) R. Etheridge, 1888, ‘ Foss. Brit. Is.’ 
vol. i (Paleozoic) p. 113. 

Description.—Shell elongated, conical, composed of more than 
four whorls. Whorls increasing gradually, high, smooth, slightly 
convex. Sutures of moderate depth, rather oblique. Sinual band 
situated slightly above the middle of the body-whorl, and near the 
middle of the higher whorls, flat, very little depressed, bounded by 
a groove on each side. Lines of growth strong, sharp, retreating 
very obliquely backward to the band and forward again below, 
invisible on the band itself. Aperture subovoid. Columella slightly 
thickened and arched forward. Base produced. 

Remarks and Resemblances.—This species was described 
by M‘Coy as a variety of M. cingulata (His.), from which it is dis- 
tinguished by its narrower whorls, the higher position of the band, 
and more produced base. In M‘Coy’s figure a keel is represented 
below the suture, but I cannot discern any distinct traces of it, there 
being merely part of the matrix left in some of the sutures, What 
appear to be grooves limiting the band may be the result of wea- 
thering, and originally there may have been a raised thread on each 
side, as is usually the case in Hormotoma, but these threads are 
generally so slight as to be easily obliterated. The specimens are 
greatly compressed, so much so that it is impossible to make a just 
comparison with other species. H. Griffitht bears some likeness to 
H., articulata, but is of much greater size; there are no signs of 
lines of growth on the band, and the whorls are apparently not so 
convex. HH. similis resembles it more in size, but the position of 
the band is much lower. 

Dimensions and Locality.—There are only two specimens 
in the Museum of Science and Art, Dublin, both fragmentary, greatly 
compressed, and partially embedded in the matrix. That figured 
in Pl. XXII, fig. 3, consists of four whorls which measure 44 mm. in 
length. It is from Cappacorcogue, Cong (Co. Galway). The other 
(Pl. XXII, figs. 4 & 5) alone shows the lines of growth, but has only 
two and a half whorls preserved, which measure 44 mm. in length, 


268 MISS JANE DONALD ON THE GENERA [May 1899, 


and 23mm. in width. It occurs in grey calcareous slates at 
Kilbride, Cong. M‘Coy states that this species is not uncommon 
at the former locality, but is rare at the latter. 

Horizon.—In rocks of Wenlock age. 


HoRMOTOMA SIMILIS, sp. nov. (Pl. XXII, fig. 6.) 


Description.—Shell elongated, turreted, composed of more than 
three whorls. Whorls slightly convex, smooth, with the exception 
of a thread at the suture. Band level with, or rather depressed 
below the surface, situated below the middle of the whorls of the 
spire, and near the middle of the body-whorl, but slightly defined 
by an indistinct thread on each side. The lines of growth curve 
very obliquely forward from it below, and are not well seen above. 
Aperture imperfectly known, apparently longer than wide. 

Resemblances.—This species appears to be intermediate 
between HA. Griffitht and H. articulata. It resembles the first in 
general form, so far as can be judged, considering that the specimens 
of both species are greatly compressed ; but it is rather smaller, and 
the band is situated much lower down on the whorl. From the 
latter it 1s distinguished by its greater size, the lower position of 
the band, and its less convex whorls. 

Locality and Horizon.—There is only one specimen 
(Pl. XXII, fig. 6)in the Fletcher Collection in the Woodwardian 
Museum, Cambridge, from the Lower Ludlow of Dudley. It is 
broken and much flattened by pressure. The fragment consists 
of only the three lower whorls, which measure 29 mm. in length 
and 154 mm. in width. 


Hormoroma articunata (Sow.). (Pl. XXII, figs. 7 & 8.) 

Pleurotoma articulata, J. Sowerby, 1839, ‘Sil. Syst.’ p. 612 & pl. v, fig. 25. 

Murchisonia articulata, A. d@’Archiac & E. de Verneuil, 1841, Bull. Soc. géol. 
France, vol. xii, p. 160; F. M‘Coy, 1846, ‘Syn. Silur. Foss. Irel.’ p. 16; H. G. Bronn, 
1848, ‘Index Paleont.’ p. 747. 

Pleurotoma articulata, T. Brown, 1849, ‘ Ilustr. Foss. Conch. Gr. Brit. & Irel.’ 
p. 253 & pl. xxxvii*, fig. 20. 

Murchisonia articulata, A. d’Orbigny, 1850, ‘ Prodr. Paléont. strat.’ vol. 1, p. 31; 
J. Morris, 1854, Cat. Brit. Foss. p. 258; J. Sowerby, 1867, ‘Siluria,’ 4th ed. pl. xxiv, 
fig. 2; J. J. Bigsby, 1868, ‘ Thes. Sil.’ p. 157. 

Hormotoma articulata, J. W. Salter, 1873, Cat. Cambr. & Silur. Foss. p. 172. 

Murchisonia articulata, J. D. La Touche, 1884, ‘Geol. of Shropshire,’ p. 80 & 
pl. xviii, fig. 635; F. Roemer, 1885, Pal. Abhandl. vol. ii, pt. v, p. 125 & pl. ix, 
fig. 18; R. Etheridge, 1888, ‘ Foss. Brit. Is.’ vol. 1 (Paleozoic) p. 113. 


Description.—Shell very elongated, turreted, composed of more 
than ten whorls. Whorls increasing gradually, high, convex, 
smooth. Sutures deep, moderately inclined. Sinual band situated 
near the middle of the whorl, level with the surface or but slightly 
depressed, defined either by a very fine thread on each side, or 
merely by the lines of growth. Lines of growth retreating very 
obliquely backward above the band, and forward below, strongly 
arched on the band itself, indicating a deep sinus in the outer lip. 
Aperture subovoid. Columella rather inclined, arched forward, 
slightly thickened. Base produced. Umbilicus closed. 


Volb.ss. | ECTOMARIA AND HORMOTOMA. 269 


Remarks and Resemblances.—This species was first de- 
scribed by Sowerby in ‘ The Silurian System’ as Pleurotoma articulata. 
Succeeding paleontologists referred it to Murchisonia, but Salter 
(‘Cat. Cambr. & Silur. Foss.’ p. 172) was the first to place it in 
Hormotoma, which he regarded as a section of Murchisonia. It is 
remarkable for the height of the whorls and the great obliquity of the 
lines of growth above the band. In this latter character it resembles 
HT. Griffiths and H. antiqua. It is also like the former in having 
high whorls and a submedian band, but the whorls are more convex, 
and the shell is much smaller and more slender. The broad, very 
slightly convex whorls and low position of the band distinguish 
 H. antiqua from it. 

Locality and Horizon.—The type-specimen (Pl. XXII, fig. 7), 
which isin the Museum of the Geological Society of London, is from 
the Upper Ludlow of Dog Hill, Ledbury ; it is compressed, and the 
apex is broken, leaving five whorls, which measure 22 mm. in length 
and 64 mm.in width. In the Woodwardian Museum examples of this 
species are recorded from three different localities, namely, Lambrigg 
Fell and Benson Knott, Kendal, and Dudley. The specimens from 
the two first-named localities are too imperfect for identification. 
That from Dudley is probably this species, but it is partly an internal 
and partly an external mould, consisting of about nine whorls, which 
measure 39 mm. in length (Pl. XXII, fig. 8). The Museum of 
Practical Geology, London, contains two specimens from the Lower 
Ludlow of Ledbury, which are neither of them entire; one is 
undoubtedly this species; the bad condition of the other prevents 

‘certainty in its identification. There are also some casts from 
Underbarrow, Kendal, marked WM. articulata, which are not well 
enough preserved to make out what they are. An example in the 
Piper Collection in the British Museum (Nat. Hist.), from the 
Lower Ludlow at Colston’s Corner, Ledbury Dome, is probably this 
species, but it is so much weathered that it is impossible to be quite 
sure. Mr. Madeley (Stourbridge) has a specimen in his collection 
from the railway-tunnel shale of Sedgley. This shale is situated 
above the Wenlock Limestone and below strata of Lower Ludlow 
age. In the Science and Art Museum, Dublin, there is an internal 
and also an external mould in rock of Wenlock age from Tonlegee, 
Cong; these are marked M. articulata, but their poor state of 
preservation makes it impossible to determine the species. Ludlow 
is given as another locality in ‘The Silurian System,’ but I have not 
seen any well-authenticated specimens from there. Some casts 
embedded in matrix in the Ludlow Museum, from the Upper 
Ludlow of Whitcliffe, are labelled articulata, but the surface is 
absent, and the traces of the band which remain make it appear 
narrower aud more deeply grooved than in the type. Phillips! gives 
the following localities for this species :—Frith Farm, Malvern; 
Welsh Court, Bodenham, and Shucknall in the Woolhope District ; 
Llangibby in the Usk district; Golden Grove in the Llandeilo 
District ; and Marloes Bay. I have not, however, seen any 


1 Mem. Geol. Surv, vol. ii, pt. i (1848) p. 258. 


270 MISS JANE DONALD ON THE GENERA [May 1899, 


examples from these places. Roemer refers a cast from the Upper 
Silurian of Rostock, Nieder-Kunzendorf, and Lerchenborn somewhat 
doubtfully to this species. A. von Alth? and F. Schmidt * record it 
from the Silurian of Podolia; and the last-named author?’ also 
mentions its occurrence, under the name of Pleurotomaria articu- 
lata, in the Island of Gotland; Lindstrom, however, thinks that the 
shell referred to may be the species named by him Murchisonia 
moniliformis. 


HorMoToMa ANTIQUA, sp. nov. (Pl. XXII, fig. 9.) 


Description.—Shell very elongated, turreted. Whorls more 
than twelve, increasing gradually, smooth, slightly convex, wide in 
proportion to the height. Sutures deep. Sinual band situated on the 
lower half of the whorl, near the anterior suture, slightly depressed, 
limited on each side by a raised thread. Lines of growth strong, 
sweeping very obliquely backward to the band above, and forward 
below, indistinct on the band itself. Aperture rounded, rather 
produced below, inner lip reflected on the body-whorl. Columella 
nearly straight. 

Remarks and Resemblances.—tThis species is remarkable 
for the great obliquity of the lines of growth above the band, and for 
the low position of the band; the whorls are also flatter than in the 
type of the genus. In the former characteristic it resembles 
H. articulata, and to some extent H. Griffithi, but from both it is 
distinguished by the much lower situation of the band and the great 
width of the whorls. The position of the band resembles that of 
H. cingulata, but there the lines of growth above are not so oblique, 
- and the whorls are still less convex. It is most lke H. Anna, 
Billings, but the band is narrower and rather higher in that species, 
the lines of growth less oblique, and the whorls not quite so wide. 
he width of the whorls in H. antiqua is about twice the height. 
In general form it greatly resembles Ectomaria Nieszkowskwi, but 
has not its prominent ornamenting keels ; and the lines of growth, 
though not distinct on the band, as seen above and below, appear 
to indicate the deep sinus characteristic of Hormotoma. 

Dimensions.—l have seen only one really good specimen of this 
species; it is in the Geological Survey Collection, Edinburgh Museum, 
but there are ten worn fragments associated with it, from the 
same locality, which are possibly identical. The length of the 
example figured (Pl. XXII, fig. 9) is 56 mm., and the width is 
about 138 mm. 

Horizon and Locality.—Durness Limestone, Sutherland. 


Hormoroma GRAYIANA, sp. nov. (Pl. XXII, fig. 10.) 
Description.—Shell very elongated, conical, composed of more 


1 « Palaoz. Gebilde Podoliens u. deren Verstein.’ Abh. k. k. geol. Reichsanst. 
vol. vii (1874) p. 31. 

2 ‘Bemerk. uber die Podolisch-Galizische Silurformation u. deren Petref.’ 
Verh. russ. k. mineral. Gesellsch. ser. 2, vol. x (1876) p. 16. 

3 «Beitrag zur Geol. der Insel Gotland,’ Archiv Naturk. Liy-, Ehst- u. 
Kurlands, ser. 1, vol. 11 (1861) p. 441. 


JDonald del. 
F.H. Michael lth. 


BC POMARTA, é HCE MO TO MEAS” 


by 


Woliss: | ECIOMARIA AND HORMOTOMA. 271 


than eight whorls. Whorls increasing gradually, convex, smooth, 
with the exception ofa raised thread just below the suture. Sinual 
band situated below the middle of the whorl, level with the surface 
or but slightly depressed, limited by a raised thread on each side. 
Lines of growth fine, sharp, curving strongly backward to the band 
above, and still more obliquely forward below, not visible on the 
band itself. Aperture imperfectly known, probably subovoid. 

Resemblances.—This species may be distinguished from LH. 
Saltert by its greater size, apparently higher whorls, the lower 
position of the sinual band, and by having a strong raised thread 
below the suture instead of merely a swelling. It resembles that 
species, however, in the structure of the band, the smoothness of 
the whorls, and the character of the lines of growth. 

Dimensions.—The best-preserved specimen is figured in 
Pl. XXII, fig. 10; it is crushed and imperfect, both apex and 
base being broken; the eight existing whorls measure 40 mm. in 
length, and the penultimate whorl measures 10 mm. in width. 
Three other individuals are associated with this, but they are mere 
casts, and are too imperfect to be identified with certainty. 

Locality and Horizon.—All the examples are in Mrs. Gray’s 
collection, and occur in rocks of Middle Llandovery age [{ Lapworth] 
at Woodland Point. 


EXPLANATION OF PLATES XXI & XXII. 
Beane: 


Figs. 1 & 2. Hctomaria pagoda (Salt.) var. Peachii nov. Fig. 1. Laterally 
compressed, X2. Fig. 2. Fragment of another specimen, X 2. 
Durness. Geol. Surv. Coll., Edinburgh Museum. 

3&4. EH. pagoda (Salt.) var. orientalis nov. Fig. 38, x2. Fig. 4. 
Aperture of another specimen, X2. Durness. Geol. Surv. Coll., 
Edinburgh Museum. 

Fig. 5. EL. girvanensis, sp. noy. Specimen partially embedded in matrix, x 14. 
Minuntion. Gray Coll., Edinburgh. 

6. E£. (4) exigua, sp. nov., X4. Minuntion. Gray Ooll., Edinburgh. 

Figs. 7-11. Hormotoma Salteri, Ulr. & Sco. Fig. 7, x2. Fig. 7a. View 
of base, x2. Fig. 7 6. Side view of body-whorl, x2. Fig. 8. 
Another specimen on the same piece of rock, X2. Durness. Geol. 
Surv. Coll., Edinburgh Museum, Fig. 9. Front view of specimen, x 2. 
Fig. 10. Back view of another, nat. size. Fig. 11. View of aperture 
of same, nat. size (probably the var. nitida, Ulr. & Sco.), for com- 
parison, from tlie Trenton formation, Allumette Island. British 
Museum (Nat. Hist.). 

Fig. 12. H.(?) gracillima (Salt.). Nat. size. Durness. Museum of Pract. 
Geol., London. 

13. H. (?) dubia, sp. nov. Nat. size. Durness. Museum of Pract. Geol., 
London. 

Figs. 14-17. A. cingulata (His.). Fig. 14. View of specimen partially embedded, 
nat. siz2. Aymestry. Museum of Geol. Soc., London. Fig. 15. Front 
view of type of Zerebra (?) sinuosa, Salt., nat. size. Mocktree. Lewis 
Coll., British Museum (Nat. Hist.). Fig. 16. Portion of whorl of 
specimen showing lines of growth, slight angularity above the suture, 
and apparent depth of sinus, X 2. Grindrod Coll., Oxford University 
Museum. Fig. 17. Portion of whorl of another specimen, showirg 
lines of growth and some of the spiral ornamenting threads, x2, 


Knapp Lane, Ledbury. Piper Coll., British Museum (Nat. Hist.), 


272 ECTOMARIA AND HORMOTOMA. [May 1899, 


Puate XXII. 


Figs. 1 & 2. Hormotoma Piperi. sp. nov. Fig. 1. Front view, nat. size. 
Fig. 2. Back view of another specimen which is slightly compressed, 
nat. size. Knapp Lane, Ledbury. Piper Coll., British Museum (Nat. 
Hist.). 

3-5. H. Griffithi, sp. nov. Fig. 3. Specimen partially embedded in 
matrix, nat. size. Cappacorcogue, Cong. Fig. 4. Back view of 
another specimen, nat. size. Fig. 5. Front view of the same, nat. 
size. Kilbride, Cong. Museum of Science & Art, Dublin. 

Fig. 6. H. similis, sp. nov. Back view, nat. size. Dudley. Woodwardian 
Museum, Cambridge. 

Figs. 7 & 8. H. articulata (Sow.). Fig. 7. Front view of type, X2. Fig. 7a. 
Penultimate whorl, x 6, showing the lines of growth. Dog Hill, 
Ledbury. Museum of Geol. Soc., London. Fig. 8. Front view of 
another specimen, X13. Dudley. Woodwardian Museum, Cambridge. 

Fig. 9. H. antiqua, sp.nov. Front view, nat. size. Fig. 9a. Back view of 
body-whorl, X13. Durness. Geol. Surv. Coll., Edinburgh Museum. 

10. H. Grayiana, sp. nov., X13. Woodland Point. Gray Coll., 
Edinburgh. 


Discussion, 


Prof. Sertey and Prof. Soxtas spoke. 


Quart. Journ.Geol.Soc.Vol.LV,P1. XXII. 


J.Donald del . 
FH Michael lth. 


Mint ern. Bros.imp. 


HORMOTOMA. 


oe oe 


y * 


A 


, 
q 


Vol. 55.] AGE OF TYRONE AND LONDONDERRY GRANITES. 273 


18. On the Ace of certain Granites in the Counties of Tyrone 
and Lonponpverry.’ By Prof. Grenvitte A. J. Curr, F.G.S. 
(Read March 22nd, 1899.) 


In a recent paper’ on the geology of Sheve Gallion, in the County 
of Londonderry, I had occasion to discuss the age of the granite 
which forms so large a part of the basal mass of that mountain. 
Repeated visits to the moorland farther west have convinced me as 
to the identity of the granite of Eastern Tyrone with that of Slieve 
Gallion itself; and thus any section elucidating the relations of 
the former rock to its surroundings is of interest, on account of its 
bearing on a very considcrable area. 

Mr. Joseph Nolan * in 1878, during his survey of this obscure 
and difficult district, found no satisfactory sections in the granite- 
area north of Beragh. The rock is here surrounded by Lower Old 
Red Sandstone, and is exposed sparingly in the floor of a broad 
valley. The Camowen River at present flows in the middle of a 
strip of cultivated alluvium, with only a few boulders to indicate 
the granite in its bed. In his paper published in 1879, Mr. Nolan 
refers to an induration of the sandstone at Drumduff Bridge as 
probably due to the action of the granite. He cites, however, the 
section at Aghnagreggan Bridge, west of Carrickmore, as affording 
far clearer evidence. 

The best discussion of this section occurs in the Survey memoir 
of 1878, for it is there pointed out that the granite, regarded as 
intrusive in the Old Red Sandstone, is still pre-Carboniferous. 
The Lower Carboniferous beds near Moneymore are thus full of 
débris from the granite of Slieve Gallion. The evidence in the 
townland of Aghnagreggan, upon which reliance is placed, is that 
Devonian grits, in contact with the granite, are ‘vitrified and 
converted into quartzite. The unaltered sandstones nearer the 
main road are, of course, duly noted. 

When Mr. Nolan wrote, the views held by Portlock as to the 
metamorphic origin of the granite of this area were still prevalent 
in the writings of his successors, and Mr. Nolan was departing 
from traditional lines in regarding any part of the granite as 
intrusive. His reference to the ‘yellowish quartzite, * however, 
makes it possible that he regarded a fine-grained yellowish granite 
near the junction as an altered grit, and was consequently misled 
in his reading of the section. 

_ After my paper on Sleve Gallion had been published, Mr. J. 
St. John Phillips and myself examined the rocks west of Pomeroy ; 
and Mr. Phillips opened up a junction of granite and sandstone in 
Aghnagreggan, a little south of the boundary shown upon the 


1 [This paper was read under the title of ‘A Critical Junction in the County 
of Tyrone. | 
' * Trans. R. Dublin Soe. vol. vi (1897) p. 243. 
*® Geol. Surv. Irel. Expl. Mem. Sheet 34 (1878) p. 15, and ‘On the Meta- 
morphic & Intrusive Rocks of Tyrone, Geol. Mag. 1879, p. 159. 
- + Geol. Mag. 1879, p. 159. - 


Q.J.G. 8. No. 218. , r 


274 PROF. G. A. J. COLE ON THE AGE OF CERTAIN [ May 1899, 


Geological Survey Map, Sheet 34. While we could detect in the 
field no alteration in the soft red sandstones, yet the curious inter- 
mingling of granite and sedimentary rock seemed fair evidence of 
intrusion. 

The specimens collected were examined microscopically ; but no 
evidence of metamorphism was even then procurable from the 
sandstone. This is a fine-grained reddish-brown rock, consisting of 
angular quartz-grains and abundant pale mica; the mica is bent 
against the quartz and is clearly detrital. The tufted patches of 
muscovite that also occur probably represent altered potash-felspar. 
which was converted into muscovite before it was washed into the 
sandstone. The felspar of the adjacent granite is frequently in this 
condition. One or two broken prisms of tourmaline, and clear 
grains of triclinic felspar, also lie in the thin sections of the sand- 
stone. The opaque cement is limonitic. 

There is no material in this Devonian sandstone which could not 
be derived from the underlying granite; the grains, moreover, are 
but little waterworn. The granite, both at the contact and in the 
grit-like mass exposed above Aghnagreggan tuck-mill, is finer in 
erain than much of the local granite; that of the new exposure at 
ore for instance, in Mullaghslin Glebe, 2 miles to the west, 
is far more typical and coarse. This fact may show that we are 
near the surface of cooling of the original granite-dome, but it is 
not in itself evidence of intrusion. The Aghnagreggan granite, 
moreover, shows many signs of alteration. The felspars are full of 
minute tufty muscovite; and rusty brown granules, which I regard 
as ferriferous epidote, abound throughout them. Similar granules 
occur in the felspar of the curious granite of Limehill Upper, north 
of Pomeroy. which is rich in calcite; and in the aplite of Carndaisy 
Glen, on Slieve Gallion, where the brown particies have arisen, 
together with rutile, freely in the altered biotite, and less freely 
in the felspars. Calcite occurs also in this latter rock, and 
lime may have been imported from without. Whatever its nature, 
the ferruginons brown alteration-product in the Aghnagreggan 
granite wonld impart ample colouring-matter to anv sediment 
formed in the vicinity. The granite at the tuck-mill is thus stained 
and flecked with orange, the decane felspars giving it a further 
resemblance to the adjacent sandstone-series. 

It became necessary, then, to revisit this critical section, and to 
obtain a larger exposure along the bank of the little Granagh Burn, 
in which it had been originally unearthed. The result is to prove 
the derivation of the sandstone in Jarge part from the granite, and 
to destroy the theory of intrusion of the granite into the sandstone. 
Along ‘a slightly varying level in the sandstones, irregular lum] s 
of granite, sometimes bounded by joints, sometimes subangular, are 
found abundantly, and form more than half the bulk of certain 
specimens brought away. Large quartz-grains, and flecks of granite 
partially broken up, occur in the groundwork of this junction-rock. 
Vertically below it, larger masses of granite come in, which may 
be only great boulders on the pre-Devonian land- surface. Fnough 
is seen, however, to show that here the granite occurs practically in 


i 
7 


Vol. 55.] ° GRANITES IN TYRONE AND LONDONDERRY, io 
mass, giving off its detritus on its irregularly weathered sur- 
faces; 500 feet away, the fine-grained decomposing granite 18 seen 
definitely 2m situ at the tuck-mill. | 


Sandstone containing fragments of granite, Aghnagreggan(Co.Tyrone). 


[About 2 nat. size. ] 


In the paper on Slieve Gallion already quoted,’ I compared the 
granite with that of Crossdoney, near Cavan, which is post-Silurian 
but pre-Devonian, like so many masses throughout Ireland. There 
is now no difficulty in regarding the intrusive rocks of Beragh, 
Pomeroy, and Lissan as connected with the great ‘ Caledonian’ 
epoch of mountain-building. The axis along which they appear 
has, moreover, the characteristic north-easterly and south-westerly 
trend. Except for its association with somewhat dubious cherts,” 
which may be of Arenig age, the volcanic series penetrated at various 
points by the granite lends no stratigraphical assistance. Some of 
the strikingly fossiliferous beds, referred to the Bala Series, near 
Pomeroy, contain much secondary mica, developed over the surfaces 
of the fossils. But they are not in any sense metamorphosed, 
and are mapped as merely faulted down against the hornblende- 
granite of Bardahessiagh. ‘The determination of the age of the 
voleanic series of Sheve Gallion and Eastern Tyrone would limit the 
possible antiquity of the granite; the critical section in Aghna- 
greggan, above described, tells us only one end of the story. 

1 Trans. R. Dublin Soe. vol. vi (1897) pp. 243-245. 

* Ibid. p. 239, & Sir A. Geikie, ‘ Ancient Volcanoes of Great Britain,’ vol. i 
(1897) pp. 239-241. 

tT2 


276 PROF. T. G. BONNEY AND MISS C. A. RAISIN ON [May 1899, 


19. On Varteriss of Serpentine and AssocrateD Rocks in ANGLESEY. 
By Prof. T. G. Bonny, D.Se., LL.D: V.P.B.S., 1 .Giseaee 
Miss C, A. Raisin, D.Sc. (Read February 22nd, 1899.) 


[Puate XXTIT.] 


ConrTeEnTs, 
Page 
I. General, Deseripirom iy. 6 U4 dian cnn -oe See ere 276 
(1) Mainland of Anglesey—south of Valley Station. 
(2) - - near the Lakes. 


(3) south of Llanfair-yn-neubwil Inlet. 
(4) Holyhead Island—Rhoscolyn Parish. 
II. Serpentine. 

(a) Macroscopic Characters ~ .....-0cssne, svc .-cs sees eeen eee 280 

(1) Normal Varieties. 
' (2) Banded Serpentine. 

(3) Variolitic Serpentine. 

(8) Microscopie Characters)“. c2cvraacmncdscsasds+maeeee eee 284 
(1) Normal Varieties. 
(2) Variolitic Serpentine. 


TT! *@phicalenes. Cee cr eee Cee i 289 
EV ..<Other Intrusive Woks) Wi. 0o 5. c5 loinc ok nossa acacn oaeene ake eee eee 290 


(1) Pyroxenites, Enstatite-rock, ete. 
(2) Gabbro. 

(3) Porphyrite (?). 

(4) Greenstones. 


V- Actinolite-tults in Roeks near Junctions. ...-........<.s00-0+ essen 294 
Vim~eChloritesock and (Tale=s@histinlenc. ees saanasetew cued cos ccee eee 297 
Nip viittects of, Pressure; Ageot the Docks 2. isc. .c.t<..0q1-) eee eee - 800 - 


I. Generat Descriprion.} 


(1) Mainland of Anglesey—south of Valley Station. 


On the eastern side of the ‘strait’* is the gabbro at Graig-fawr 
described in a former paper by one of the present authors? A 
serpentine, there indicated as ‘ about 70 yards to the north’ of this 
mass, has been quarried further,’ and parts of the rock exhibit a 
slightly variolitic character. The junction of schist with serpentine 
or ‘ ophicalcite’ noticed and figured (op. cit. p. 41, fig. 1) is in a 
low cliff by the shore almost due south of Graig-fawr and near a 
-boss of variolitic serpeutine, described on p. 281. This junction 
is not easy to interpret; but further study of the rocks atfurds some 


1 IT am bound to state that, though I have been once or twice on the ground 
since 1880 (when my paper was written), the whole of the laborious field-work 
for the present communication has been done by Miss Raisin, but that we are 
jointly responsible for the examination of specimens and the interpretation of 
results.—T’. G. B. 

2 We apply this term to the water separating Holyhead Island from 
Anglesey. In the district it is called the ‘river.’ 

3-1. G. Bonney, Quart. Journ. Geol. Soc. vol. xxxvii (1881) p The 
gabbro is there described as ‘ near Ty-newydd’ (as shown on the i deh map). 
‘he names in the present description are taken from the 6-inch Ordnance 
Survey nap. 

4 The mas still more recently has been quarried, and carted away. 


Vol. 55.] SERPENTINE AND ASSOCIATED ROCKS 1N ANGLESEY. 277 


evidence favourable to the hypothesis of a fault. The green schists 
have a squeezed appearance, but the brecciation and crushing of 
the rock adjoining them are still more marked. In it are angular 
fragments coloured by hematite, the whole being permeated by 
carbonates!; hence the rock is one of the so-called ‘ ophicalcites.’ 
Near by are foliated masses, including a squeezed diallage-enstatite- 
rock associated with serpentine and gabbro. Lenticles of the rock 
have escaped, while surrounding parts have been crushed. 

Bosses of gabbro occur in the fields between here and Tyddyn-y-cob” 
Inlet, where the rock becomes schistose. The gabbro reappears inland 
beyond the sluice, and extends as far as the outcrops of schist near 
Glan-rhyd-uchaf and east of the railway, but is interrupted south 
of Cruglas by serpentine and ‘ophicalcite,’* the latter rock being 
brecciated and in places reddened by hematite. 


(2) Mainland of Anglesey—near the Lakes. 


Large bosses or mounds of gabbro occur in the fields along the 
northern border of Llyn Dinam,* two of them rising abruptly from 
the water. Between these are bosses of serpentine, one of which 1s 
quarried, and others occur close to Dinam Fawr. The serpentine is 
mostly schistose, occasional ‘eyes’ only being left, but a small 
boss of uncrushed rock shows an interesting and rapid change in an 
enstatite-serpentine. 

Numerous boulders’ of various rocks occur in some of the fields 
north-east of the lake, as well as bosses of schist; while, farther 
south, between the two lakes, many of the latter are conspicuously 
ice-worn. Gabbro extends from south of Llyn Dinam and some 
islet-hke masses in the marsh to the island in Llyn Penrhyn: it 
is cut by dykes varying from diabase to not very fresh basalt. 

The serpentine, which here again borders the gabbro and separates 
it from schists on the west and south, is interesting from the way in 
which it weathers. It is generally much crushed, and the surface 
of the bosses exhibits thin lamine, often with crumpled edges, 
varying in colour from dark pistachio-green to a greyish-blue,. 
Frequently ‘eyes’ of serpentine have escaped the crushing; one 
of these, a dull slaty-blue compact rock, measuring roughly 3 feet 
-in length, contrasted so strikingly with the crushed serpentine 
around, that it might have been taken for an intrusion or an 
included lenticle. In some places angular fragments of white 
dolomitic veins,’ often schistose, are conspicuous in the dark serpen- 
tine and resemble enclosures. This seems to show brecciation in a 
rock already veined by a carbonate, and the much-crushed rock 
adjoining was probably similar, In one mound (mainly of ser- 


1 As proved by its effervescence when treated with hydrochloric acid. 
2 «Tyddyn Gob’ on the l-inch Survey map. 
% Described in Quart. Journ. Geol. Soc. vol. xxxvii (1881) p. 42. 
‘Llyn Trefias ’ on the |-inch Survey map. 
eee is a picrite, many are dolerite. Boulders have been only incidentally 
studied. 
° Hardness about 4; effervesces with hydrochloric acid somewhat slowly. 


cs 


4 


278 PROF. T. G. BONNEY AND MIss C, A. RAISIN ON [May 1899, 


pentine*) some dull greyish-green rocks appear to include a compact 
diabase and a streaky, probably crushed, gabbro (see p. 293). 

South of the streamlet and west of Llyn Penrhyn, several large 
bosses occur, some composed of serpentine, some including other 
rocks (chlorite-schist, gabbro, etc.) ;* but from this place all the 
ground southward to the railway, and westward towards 'Treflesg, 
is mainly occupied by dull pale-green ‘schists,’ sometimes with 
crumpled laminz, sometimes with lustrous sheen-surfaces, occa- 
sionally quarried. 

Gabbro forms abrupt masses (where Yr-ynys is built), while east 
of Caeglas some serpentine and ‘ophicalcite’ occur, with a little 
chlorite-schist. The gabbro and the green schists can be traced 
across the railway, and the serpentine may also extend to the field 
beyond, where it is quarried. Craglets, at first of schist, afterwards 
of gabbro, project above the low meadows, and lead to the lirge 
mass of gabbro which rises abruptly with a plateau-like summit 
towards Felin-carnan. 


(3) Mainland of Anglesey—south of Llanfair-ya-neubwll 
Inlet. 


A small patch of serpentine (much crushed) forms a low cliff and 
the rock on the teach south-west of Felin-wen.’? North of it a 
modified diallage-rock (containing some enstatite) occurs, which is 
probably a dyke; while a brecciated dolomitic limestone is found a 
little farther southward along the shore, and at the western end of 
the causeway near Penryn-hwled. A small boss of serpentine and 
limestone, or ‘ ophicalcite,’ is quarried in a field east of the road 
south of Plas.’ 


(4) Holyhead Island—Rhoscolyn Parish. 
(a) General Description, and Boundary-line. 


On the west of the ‘ strait’ is the larger district of serpentine and 
associated rocks which form a somewhat tongue-shaped area, about 
2 miles from east to west and 4 mile from north to south. The 
boundary is irregular, and the rocks in places, especially on the 
south, rise abruptly from marshy land. To the north, the schists 
are well exposed in large bosses, but among them, one small piece 
of serpentine is quarried immediately north of the Holyhead road 
(north of Plas-rhyd-bont). The serpentine and other rocks often 
show, towards the boundary, a breeciatcd and even a smashed cha- 
racter, and the schistose planes (like the lamine of the schists) 
generally dip northward at a moderate angle. ‘Thus the boundary 
may correspond, partially at least, with a thrust-plane. 


1 This rock, like many masses, especially of serpentine or of chlorite-schist, 
affords good examples of surfaces polished by sheep rubbing against thein. 
_.? One junction is discussed on p. 295. 

3 Described as near Ty-ucha (on the l-inch map) in Quart. Journ. Geol. 
Soe. vol. xxxvii (1881) p. 41. 

4 Prob.bly that ‘near Gwrthya,’ ibid. p. 42. 


Vol. 55-] | SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. 279 


(6) The Coast west of the Strait. 


On the coast, south of the muddy shore extending from Four- 
mile-Bridge, are small reefs of schist or of schistose rocks. The low 
cliffs on the north of the first small inlet include variolitic rock (pale 
green, and associated with a carbonate), a much-crushed, probably 
diallage-rock, gabbro, and serpentine. A series of ‘schists’ below 
the gabbro-crag have suffered great crushing, which probably acted 
along a thrust-plane. 

Southward, at intervals, occurs serpentine with interspersed 
varieties of enstatite-serpentine and diallage-serpentine ; and ensta- 
tite-rock is found in the low point to the south, in the outlying islet, 
and as a small dyke along the northern shore of the next large 
inlet. Here a diullage-rock is still better exposed as a dyke with 
branching veins. Farther along this shore (south of Rhyd-bont) is 
a serpentine with very large crystals of lustre-mottled diallage and 
eustatite (see pp. 250, 285). 

South of the inlet, serpentine is soon followed by gabbro, which 
forms couspicuous masses. On the shore below Dinas-bach a dyke 
of gabbro,’ running roughly from west to east, cuts the ser- 
pentine. The outlying rock in the sand is a green ‘schist,’ which 
may be partly, if not wholly, a modified-gabbro or diabase. Rock, 
probably similar, occurs at intervals in the peninsula to the eastward. 
An ophicalcite is found in the field near Dinas-bach, while serpentine, 
gabbro, and associated rocks occur near to and east of Fadog. 


(c) Serpentine. 


In the interior of the district, bosses and crags of serpentine 
exhibit variations chiefly due to accessory minerals. An example 
with lustre-mottled crystals, mainly of diallage, occurs south of 
Cerig-moelion Farm. 

The serpentine includes many variolitic patches, which occur 
rather towards the northern boundary, as if they might continue 
the line of the Graig-fawr outcrops. A variolitic structure is some- 
times suggested rather than clearly indicated (as in the fields around 
and south of Rhyd-bont), but the patches of well-developed varioles 
are small, the largest being not more than 10 to 20 feet across. 


(d) Chief Gabbro-Masses. 


Large masses of gabbro are found at several places, generally 
forming steep-sided plateau-like rocks. Thus one smaller boss 
occurs north of the head of the large inlet, south of Penrhyn-Fadog ; 
while south-east of this, clese to the mud, rises a cliff of gabbro, 
almost joining the serpentine which is quarried near at hand.” 
Farther down the inlet is the Graig-Dinas mass (one of the finest 
in this district), and other bosses are close by, including many in 
two fields north-west of Gareg-wen covert. These are roughly oval 
in shape, and the schistose planes or lamin are generally parallel 


* Apparently enstatite-gabbro ; see p. 293. 
* This junciion is described on p. 29d. 


280 PROF. T. G. BONNEY AND MISS C. A. RAISIN ON. [May 1899, 


with the longer axes of the ellipsoids. Some patches occur in the 
fields east of Fadog. West of the road a few small patches, much 
squeezed, are scattered among the serpentine.’ Then important 
masses are found immediately north of the track leading to Cerig- 
moelion. 


Ii. SerpPenrine. 
(a) Macroscopic Characters. 


(1) Normal Varieties. 


Hand-specimens of the serpentine generally do not show very 
marked differences. ‘The rock is of a dark, dull green colour, some- 
times with a tinge of purple, mottled with a rather bright green 
translucent substance resembling ‘ noble serpentine,’ which occa- 
sionally dominates, especially if the specimen shows marked signs 
of pressure. Sometimes it 1s compact and rings under the hammer, 
sometimes it is pitchy in aspect and is rather ‘ crackled,’ possibly 
indicating the approach to a junction. 

Some smali bosses, however, in the fields east of Plas-céch afford 
a fairly distinct variety. This has a glittering appearance, as if it 
abounded in minute crystalline flakes or grains with cleavage- 
surfaces, and the rock feels more gritty than ordinary serpentines 
(hardness about 3°75 to 4). It resembles an impure variety of a 
serpentine, but is etched by hydrochloric acid as readily as normal 
specimens of that rock. More marked varieties are due to the 
conspicuous occurrence of accessory minerals, of which enstatite 
and diallage are the commoner. A cleavage-surface of one or the 
other can often be seen here and there in the serpentine, and where 
this evidence is wanting, their presence is proved by microscopic 
examination. ‘These accessory minerals appear to be sporadic in 
distribution, and not limited to any locality. The most remarkable 
examples are those in which the included crystals are lustre-mottled, 
as in a crag south of Cerig-moelion, and in a cliff south of 
Rhyd-bont (see pp. 279, 285). At the last-named locality the crystals 
are exceptionally large, sometimes apparently 5 inches long, and the 
exposed cleavage-surfaces flash brilliantly in sunlight. They are 
scattered over a roughly vertical cliff-face, which extends for about 
12 yards along the northern shore of the inlet. 

Jron-oxide occurs, but, as can be seen even in hand-specimens, it 
is very variable in distribution. Sometimes it is scattered uniformly 
in small erystalline grains, sometimes it forms nests or clusters 
closely massed over a few inches.?, We proved some to be magnetite, 
but some of the grains are apparently a less opaque spinellid; while 
other grains, which with reflected light are somewhat copper-coloured, 
are possibly awaruite. 


1 The ‘ green schists’ south of the serpentine form considerable masses, many 
of which have an aspect resembling that of a gabbro. 
* As, for example, on one rock near Rhyd-bont. 


Vol. 55.] SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. 281 


(2) Banded Serpentine. 


The serpentine has in places a banded structure, perhaps best 
shown in connexion with some of the varivlitic rock described in the 
next paragraph. In other examples, and even in some of the variolitic 
forms, the rock is characterized rather by an irregular streaking than 
by a definite banding, both however being probably due to fluxion. 
In one example from behind Cerig-moelion Quarry the structure 1s 
partly schistose, but here probably pressure acted on a rock already 
banded.” 


(3) Variolitic Serpentine, 


Small spheroidal bodies are usually weathered out on exposed 
surfaces of this rock, varying from about 3 to about 3 inch across (or 
from the size of a millet-seed to that of a pea). In many spherules 
the centre is of paler colour, or even whitish, and sometimes it is 
replaced by a somewhat irregular cavity. Microscopic examination 
suggests that a carbonate has been rather abundantly present, but 
in these examples has weathered out. The spherules fcrm patches, 
in which they are irregularly grouped: though here and there 
distinct, they are generally crowded, and the crowding some- 
times becomes greater, until they form a confused aggregate 
in which no distinct spherules can be detected? In some 
bosses where no spherules can be recognized clearly, a confused 
structure suggests the incipient stage of a similar formation.* The 
spherules in a patch may be small or large; and usually different 
sizes are adjacent, or are closely associated and even mixed. 
Very frequently the patches take the form of streaks or bands, as 
in a spherulitic obsidian. ‘The rock in such cases usually shows 
a streaking in the intermediate parts, and thus a fluxion-structure 
is distinctly suggested. 

The colour and appearance of the rock differ somewhat in the 
different examples :— 

(a) South cf Graig-fawr.—The boss on the beach is roughly 
about 20 feet in length, and is prolonged by small knobs. The 
rock is of a rather bright green with a little dark mottling. It 
includes paler green spherules, commonly of the size of a millet- . 
seed. These sometimes form irregular patches, but often lenticular 
streaks or bands. The rock is very brittle, its fracture in places 
almost resembling that of obsidian, and having, when fresh, a 
glassy lustre; it is translucent, and resembles noble serpentine. 
On the weathered duller surfaces the spherules are very pale or 
whitish, and the patches of them sometimes project as slightly 
mamuillated knobs. The broken spherule often consists only of a 


' The microscope-slice shows some streaky serpentine yielding bluish polari- 
zation-tints resembling that sometimes derived from enstatite. See Quart. 
Journ. Geol. Soe. vol. xxxvii (1881) p. 45. 

* This recalls a similar transition often seen in variolitic diabase. Seo 
G. A. J. Cole & J. W. Gregory, Quart. Journ, Geol. Soc. vol. xlvi (1880) 

. 813; J. W. Gregory, ibid. vol. xlvii (1€91) p. 48; CO. A. Raisin, ibid. 
vol. xlix (1898) pp. 154, 155 & pl. i, fig. 5. 

* Sometimes they can be recognized macroscopically, where microscopic 

exauiination reveals only a confused aggregate, 


Fig. 1.—Vuriolitie serpentine, south of the ‘ School,’ and 
south-west of Ihyd-bont. . 


[Reproduced from a photograph, nat. size. ] 


The rock shows a few scattered spherulites, and streaky bands 
formed of spherulites. he lines crossing obliquely from 
right to left are veins of serpentine. The rock contains 


wwuch carbonate. 


Fig. 2.— Variolitic serpentine, east of Pwll-pillo. 


[Reproduced from a photograrh, nat. size. ] 


Varivles shown on cut surface of rock. 


Vol. 55.] SERPENTINE AND ASSOCIATED’ ROCKS IN ANGLESEY. 283 


rim or crust recalling a bubble (doubtless owing to the weathering- 
out of a carbonate). All the rock is much jointed and ‘crackled,’ 
but parts of it are more squeezed, and projecting knobs (cften 
spherulitic) seem to represent harder ‘ eyes’ in the crushed mass. 

(6) North of Graig-fawr.—It is difficult to describe the relations 
of the spherulitic parts of this rock, since they are recognizable 
only bere and there in hand-specimens. Much of the rock in the 
quarry is dark and compact; the more clearly spherulitic parts 
resemble somewhat the glassy-lovking serpentine of a, but appa- 
rently a carbonate is more generally disseminated and gives a whitish 
tint to the small spherules. 

(c) East of Penrhyn-Fadog, at the northern point of the small 
inlet.—A few square feet of rock, scattered on the beach over about 
15 yards, exhibit spherules which vary in size, being about that of a 
small pea in one boss and much less in another. In weathering, the 
dark green rock becomes a pale greyish-green, the spkerules being 
lighter in colour and projecting on exposed surfaces. ‘The whole 
mass, including the non-spherulitic parts, is usually permeated by 
a carbonate. The rock is closely associated with a much crushed 
variety containing diallage; and the low cliffs, where they project to 
the east, include a gabbro, a serpentine, and apparently ‘ schists,’ all 
crashed. 

(7) Immediately east of the Rhoscolyn road, one fieid-length south 
of the ‘ School.’-—The richly spherulitic part of this mass measures 
roughly about 10 feet each way; the remaining portion (sometimes 
of compact rock) shows little else than slickensided joint-surfaces. 
Another boss in the field contains a few spherules. The spherulitic 
rock is dark, sometimes reddish-purple, including spherules (roughly 
3 to 3 inch in diameter) varying from greyish to pale green. These 
are sometimes isolated but often in strings, almost axiolitic, and 
sometimes are massed into a small patch. The ground is crossed 
in various directions by numerous very thin chrysotile-veins, which 
traverse or surround the spherules. lather irregular joints also 
occur, sometimes filled by serpentine, occasionally 4 inch thick. 
An old surface sometimes darkens, showing greater contrast with 
the pale spherules, but a faint purplish tinge may be acquired by 
further weathering. The pale spherules are clustered closely in 
patches, some of which form bands or narrow tracts around non- 
spherulitic islets, suggesting a brecciation, which however may 
perhaps be due to flow. (See fig. 1.) 

(¢) East of Pwll-pillo.—On a grassy knoll in a field near the 
farm, spherules (mostly of the size of hemp-seed, sometimes that of 
millet-seed) are to be seen on a partly moss-covered stone (about 
5 feet across). Spherules of uniform size have a tendency to occur 
in groups, but the different sizes are often mixed. They form bands 
or vein-like parts (perhaps 13 inch wide) which themselves are a 
little depressed below the weathered surface of the intervening rock. 
This rock when fresh is dark green, compact, with an almost 
flinty fracture, but parts of the pale brown weathered face suggest 
_ spherules clotted together. (See fig. 2.) 

(f) North-west of Cerig-moelion Quarry (about one field away).— 


284 PROF. T, G. BONNEY AND MISS C. A. RAISIN ON [ May 1899, 


A boss of serpentine shows a few spherules at one part; at another 
it contains some fair-sized crystals of rather altered enstatite, and 
an appreciable quantity of a carbonate. It is very similar to the 
rock next described. 

(g) North of Cerig-moelion Farm.—On a surface (about 2x2 
feet) greenish or whitish spherules are well shown. Sometimes 
they are developed in strings or isolated in a dark ground as 
in the mass d, Adjoining this part is a dark pitchy serpentine 
coutaining narrow spherulitic veims. Beyond a sharp boundary, a 
greyish-green rock with much carbonate occurs, and in it small 
spherules are thickly clustered. This mass, like other spherulitic 
masses, probably has been affected by faulting and brecciation ; but it 
possessed previously flow-structure, as well as a brecciation, possibly 
also due to the same cause. 


(8) Microseopic Characters. 
(1) Normal Varieties. 


Thin slices of the serpentine, when examined under the micro- 
scope, frequently exhibit the well-known meshwork-structure de- 
noting derivation from olivine, or sometimes the parallel close-set 
streaks indicative of enstatite.| Other purts show with crossed 
nicols an irregujar speckling of colours. A third variety of the 
serpentine is formed of parallel close-set, almost vein-like bands. 
In a fouith the slice exhibits with crossed nicols a matted mass of 
rather narrow mica-like plates often tapering so much that the 
sections are like spines.” A fifth has the uniform character and 
bluish polarization-tints, noticed in the boulder from Cruglas, and 
attributed to alteration from enstatite (p. 281). All these forms of 
serpentine have been already described from this district by one of us.? 
A specimen may show a tendency to one or other of these variations, 
although this may have been confused by suhsequent disturbance; but 
a mixed character is frequently seen. The ‘spine’-structure is 
most marked in the rather glittering variety described from east of 
the road by Plas-céch (p. 280). 

The microscopic parallel banding suggests a possible fluxional 
character." Even within lustre-mottled crystals it often extends 
through neighbouring grains, and marks probably some original 
orientation, either in the form and direction of the grains or 
in the development of their dominant structure-planes. The 
iron-oxide is sometimes accumulated along streaks or lines,’ or it 


1 We fail to understand Mr. Blake’s remark :—‘ In only one place is the 
serpentine of crystalline aspect, as in the Lizard, Quart. Journ. Gecl. Soe, 
vol. xliv (1888) p. 481. In several places the texture and aspect of the ser- 
pentine, allowing for colour-differences, is very similar to that of the Lizard, 
and, as there, bastite-crystals are not infrequent. We have not ourselves 
observed original olivine remaining. 

2 See Quart. Journ. Geol. Soc. vol. xxxvii (1881) p. 46. 

3 Ibid. pp. 44-46. 

4 Ibid. vol. xxxiii (1877) p. 920 & vol. xxxix (1883) p. 22. 

> bid. vol. xxxili (1877) p. 919. 


—— 2 < ~ 


> SS = Come 


Vol. Ba. | SERPENTINE AND ASSOCIATED ROCKS IN ANGLSSEY. 285 


may form irregular and sporadic patches. In other specimens, it is 
apparently deposited mainly within one mineral constituent. While 
this may be olivine, in several examples the rock, judging from 
structures still perceptible, includes two varieties. of enstatite, one 
richer in iron than the other. 

The original rock, as pointed out by one of us, has been in 
some cases a dunite!; in others, where enstatite has become an 
essential constituent, it was a saxonite. Sometimes, indeed, the 
rock may have consisted wholly, or almost wholly, of that mineral, 
as in tbe Cruglas boulder.» A monoclinic pyroxene also has 
been sometimes present, in which case the rock was originally a 
lherzolite, as, for example, south of Penrhyn-Fadog Inlet. 

The minerals are associated in different ways:—(a) Sometimes 
the rock has a granular holocrystalline structure ; (>) Sometimes 
it shows lustre- mottling, generally in enstatite or diallage (pp. 290, 
291); (ec) Sometimes the augitic constituent is scattered about in 
the serpentine in larger or smaller grains. The larger are generally 
diallage, forming irregularly-distributed and sometimes associated 
patches. The smaller occur in grains of various shapes, but espe- 
cially in rather elongated irregular prisms, the latter commonly 
lying parallel and extinguishing simultaneously, thus simulating a 
pegmatitic arrangement. In some examples, the structure might 
be regarded as a result of corrosion, but in others it more resembles 
a case of intercrystallization. The serpentinous constituent for the 
most part appears to have replaced an enstatite, thus we think 
that an intercrystallization of the two minerals is the more probable 
explanation® ; (¢) In other specimens the pyroxenic constituent has 
passed into a fibrous mineral: this generally forms a matted mass, 
often occurring in clear- colourless patches, which contrast with the 
normal green or yellowish-green serpentine around them. Some- 
times, however, the patches are dull brown, as if darkened by a 
dusty deposit, which appears in some specimens to be in part at 
least a carbonate. These, however, generally indicate some tendency 
towards a variolitic character. | 


(2) Variolific Serpentine. 


Tn sections for the microscope, if at all thick, the spherules and 
the matrix are usually contrasted in colour, the one being generally 
whitish, the other rich green or yellowish-green: the latter, even in 
a thin slice, retaining a greenish tinge, though it may be pale. In 
‘most slices granules or crystalline grains of opacite are scattered, 
sometimes very thickly, over the ground, but are almost or even 
wholly absent from the spherules or aggregates. We find, however, 
in specimens from one mass well-developed crystalline grains of 


1 Quart. Journ. Geol. Soc. vol. xxxvii (1881) p. 45. 

2 Other examples are discussed in § LV, p. 291. 
_ 3 In certain slides a parallel intergrowth of the two forms of pyroxene 
seems to be exhibited ; see Rosenbusch’s ‘ Microse. Physiogr. of Rock-making 
Minerals’ [transl. J. P. Iddings] 4th ed. (1898) p. 209 & pl. xvi, fig. 5. 


286 PROF, T. G. BONNEY AND MIss C, A. RAISIN ON [May 1899, 


a deep reddish-brown spinellid, probably chromite, in the portions 
corresponding to the spherules. 

In structure, also, the two parts generally show a contrast. 
The spherules consist largely of short fibres, often in tufts or with a 
matted arrangement (Pl. XXIII, tigs. 2&4) The matrix is formed 
sometimes of an uniform greenish substance: this in places is inter- 
rupted by irregular strings or clots of iron-oxide, and separated 
into darker and paler areas, Sometimes this matrix is patchy and 
streaky: in other examples it shows a network of ferruginous 
strings, with granules of iron-oxide, deposited towards the centre of 
the mesh (Pl. XXIII, fig. L). This structure has probably existed in 
other cases, though it is not now recognizable owing to subsequent 
disturbance. With crossed nicols the greener areas always give 
the usual reactions of serpentine, varying from parts almost inert 
to strings with the wonted fairly bright polarization-tints. In 
ordinary light the fibres of the spherulcs are colourless, usually 
acicular and finely pointed ; with crossed nicols they give clear blue- 
grey tints and extinguish at a small angle. Thus they are almost 
certainly actinolite.' 

Only rarely is a concentric structure well marked, but in two or 
three slices (from east of Pwll-pillo) it appears as broad zones 
alternately clear and dark, producing a strong resemblance to 
ordinary spherulites. 

A radial structure is apparent in the spherules with concentric 
bands, as well as in some others which do not show them; but in 
most cases only an external rim, often rather narrow, is made up 
of radial fibres. In these the outline is circular, but much more 
commonly it is subrotund, even subangular, not infrequently rhom- 
boidal with rounded angles. A passage may be traced from the 
more regular shapes to irregular patches or mere clots. Within 
the crust or rim, and in the less circular forms, the matted fibres 
run sometimes mainly along two directions in the plane of the 
slide, crossing at a fairly definite angle, which (though it is not 
easy to obtain an exact measurement) often seems to be between 
50° and 60°. 

A dusty-looking finely granular material, which may be partly a 
carbonate, sometimes obscures the interior of the spherule. Often 
this encloses distinct crystals, sometimes rhomboidal in form, with 
frequent cleavages and giving bright colours with crossed nicols: 
these are probably dolomite, or possibly arkerite. ‘The boundaries 
of the rhombohedra are often imperfect, and the acicular crystals 
are intercrystallized with, and appear to penetrate into, the 
carbonate. 

A quarry north of Graig-fawr (described on p. 283) produces speci- 
mens which seem to carry the change a step farther. They vary In 
character, one being greyish-green. slightly speckled with a purple 
tint and streaked with paler, more compact-looking bands; others 
are of a brighter, more apple-coloured green, distinctly mottled with 
purplish-grey, and in these au occasional hint of a spherulitie 

1 They were tested many times for straight extinction, which might indicate 
serpentine or anthophyllite, but it was rot obtained with certainty. 


Vol. 55.] SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. 237 


structure may be found. Under the microscope, both appear 
to be composed of serpentine of the ordinary character with a 
dolomitic mineral, and a few grains or granules of iron-oxide. In 
the first type some of the serpentino tends to be streaky, and this 
is predominant in one part of the slice. Here the carbonate more 
often occurs in granular patches in which flakes of serpentine, 
variable in amount, are intercrystallized, and these patches once or 
twice are faintly radial in structure. In the second type this 
structure is often very well defined, the spherulites showing a black 
cross. ‘These sometimes have a border, more rarely also an inner 
ring, of minute flakes of serpentine ; and occasionally a little serpen- 
tine or actinohte seems to be intercrystallized with the carbonate 
(Pl. XXIII, fig. 3). Here, then, while the serpentine in parts 
of the slice continues fairly normal, the other constituent, that 
which has become spherulitic," seems to be almost entirely replaced 
by a carbonate. The spherulites in one rock north of Cerig-moelion 
are similarly replaced by a carbonate, but here the spherulitic 
structure is generally very indistinct, the only good examples in 
the microscopic slices consisting wholly of carbonate,” in which case 
of course it may be of comparatively late crigin. 

Thus in these varioles, their frequently subangular shape, their 
contrast with the adjacent serpentine, the more or less definite 
directions in which they are elongated, the uniform character 
of their fibres, all suggest that they have taken the place of some 
mineral distinct from that which has given rise to the serpentine. 
Some variety of augite or hornblende seems the most probable, 
especially one poor in iron and free from alumina, of which a 
carbonate might be a decomposition-product. The original magma 
in solidification may have separated into parts corresponding with 
olivine and pyroxene, the one afterwards producing the (more 
abundant) serpentine, the other the fibrous masses. As the latter 
are sometimes without definite shape, or form bands or streaks 
indicative of a fluxional structure, they probably did not pass beyond 
the stage of incipient or ill-formed crystals or grains, now represented, 
by the varioles. 

In certain of the rocks, a lustre-mottling of enstatite or horn- 
blende is produced by rounded crystals, which on microscopic 
examination exhibit faintly radial borders. Boulders near Graig- 
fawr show a similar structure. Sections have been prepared from 
three separate blocks. Their differences, though interesting as 
bearing on the process of mineral change, are only varictal. The 
original minerals evidently were a pyroxene (for the most part 


1 One specimen from this quarry has a vein of a pale greyish-green mineral, 
compact and uniform, almost waxy-looking, with a hardness not less than 6. 
On examination with high powers, the slice is found to be clear and colourless, 
speckled with very minute granules irregularly grouped around clearer patches. 
The latter appear to be composed of an aggregated flaky mineral with very low. 
polarization-tints, the granules giving brighter colours. The hardness is too 
high for serpentine or even pseudophitr, while the microscopic structure is nc& 
that of typical jade ; hence we suppose its affinities to be with the jadeite-group. 

* It is just possible that a very obscure form of this may have been noticed 
by Mr. Blake from near Cruglas, Brit. Assoc. Rep. 1888 (Bath) p. 409. 


288 PROF. T. G. BONNEY AND MISS C. A, RAISIN ON [May 1899, 


rhombic), olivine, and iron-oxide, apparently magnetite. The last 
Varies in quantity, but is never abundant: the first on the whole 
dominates, occurring in large crystalline grains, lustre-mottled by 
olivine, and is in various stages of change. The least altered 
is ordinary bastite, with the characteristic cleavage, faintly pleo- 
chroic,* exhibiting fairly bright polarization-tints and straight 
extinction. In places it is of a pale dull-green, and consists of a 
matted mass of steatitic fibres, which, with crossed nicols, only 
show here and there specks or gleams of whitish or brownish light. 
This might be regarded as another variety of enstatite inter- 
crystallized. with the former: but, after careful study, we came 
to the conclusion that it is more probably only a further stage of 
decomposition, though sometimes the change from the one to the 
other seems abrupt. The olivine occurs in grains of two sizes, 
the larger independent, the smaller included (Pl. X XIII, fig. 5). 
Commonly it is serpentinized in the usual way, but sometimes it 
is bordered by a zone of minute actinolite, growing lke grass 
on the edge of the bastite; sometimes it is pierced by larger 
flakes of the same, similarly related, and in one example these grow 
parallel with the fibres of the enclosing bastite, and entirely take 
the place of the small olivine-grain, which is then only obvious 
from a difference in tint. and an oblique extinction when the 
nicols are crossed; sometimes the olivine is wholly replaced by 
matted actinolite. Microliths of the same occasionally pierce the 
enstatite, in which (though rarely) they are extensively developed. 
A little iron-staining occasionally may be seen, and in one a crystal 
or two of (?)sphene. 

These structures are also exhibited by rocks en situ, especially by 
those in a craglet south of Cerig-moelion Farm.? On microscopic 
examination the included olivine-grains are frequently seen to have 
a radial border, which may exhibit certain differences. Sometimes 
the border is very narrow, and the fibres forming it rather resemble 
serpentine; they are set somewhat obliquely, but seem to. be con- 
tinucus with the central mineral.* Here the inner part shows the 
parallel vein-like structure already described, and may be derived 
from olivine; but even in these the possibility of enstatite must be 
admitted. The enclosing mineral is generally an augite or diallage, 
sometimes partly changed into pale hornblende. In one slice a 
curious modification is found: instead of the fringe around the 
included grains, clear secondary hornblende, frequently wedge- 
shaped, has grown out at the edges of the original pyroxene in the 
way which has been often described in a diabase. 


? Straw-colour with vibrations perpendicular to the easy cleavage, and sap- 
green with parallel vibrations, both pale. 

.* Also to a certain extent in the cliff south of Rhyd-bont. 

- % A marginal zone was described as a ‘ reaction-rim’ by Tornebohm (Neues 
Jahrb. 1877, p. 383) and G. H. Williams (Am. Journ. Sci. ser. 3, vol. xxx, 1886, 
p. 35); and a similar structure was attributed by W. 8. Bayley to the result. of 
change in interstitial augite, Am. Journ. Sci. ser. 8, vol. xlin (1892) p. 515. In 
the examples described by these authors the rim is formed between olivine and 
felspar ; in the Anglesey rocks, between a pyroxene and another pyroxene or 
olivine. .In any case, the structure ‘can.only be compared indirectly with the 
varioles, , 


Vol. 55.| | SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. 289 


Thus in these rocks the large pyroxene is mainly monoclinic, 
while in the boulders it is chiefly rhombic, yet it seems probable 
that the latter came from the vicinity of the former.' 

Many bosses or patches of rock, as previously mentioned, give a 
slight suggestion of spherulitic structure, which, however, does not 
become more definite on examination with the microscope ; still, 
this may denote an incipient variolitic formation. 

The occurrence of radial nodules in serpentine has been described 
by Becke, and attributed by him to the alteration of olivine-crystals.* 
We considered the possibility of this origin in the Anglesey ser- 
pentine, but deemed it improbable because of the directions of what 
seem to be cleavages, and the nature of the fibres. As a further 
test, we etched an uncovered slide with hydrochloric acid. After 
applying malachite-green, and washing, we found all the intervening 
groundmass to be stained, while only a few lines of colour appeared 
within the spherules; these probably mark some scattered and 
included fibres of serpentine. Thus the original rock was most 
likely a pyroxene-peridotite, saxonite or lherzolite, the varioles. 
representing the pyroxenic constituent.° 


III. ‘ Opnicatorre,’ 


The term ‘ ophicalcite ’ may be applied for convenience to various. 
rocks which consist partly of a carbonate of lime, partly of serpentine,. 
although they differ from the true ophicalcites, such as that of 
Connemara. The formation of these ‘ ophicaleites’ has been de- 
scribed by one of us* in the case of Cerig-moelion and some other 
masses, and to these many outcrops are similar. They show? 
brecciated fragments of serpentine with calcite, infiltrated, and 
deposited in veins.” The carbonate sometimes forms definitely 
shaped rhombohedra traversed by cleavage-planes, and penetrated. 


1 This would mean a movement in a (roughly) north-easterly direction. At 
any rate we know of no serpentine anywhere to the west, north, or east of these 
boulders. The great northern ice-sheet, advocated by some geologists, must 
have been taking a singular course in this district. 

2 Tscherm. Min. Petr. Mitth. ser. 2, vol. iv (1882) pp. 328-333, 355, & 450 ;. 
see also J. J. H. Teall, ‘On Anthophyllite from the Lizard,’ Min. Mag. vol. viii 
(1889) p. 119. 

3 Dr. J. W. Gregory speaks of a serpentine of the Cottian Alps as ‘crowded 
with needles and radial clumps of tremolite,’ Quart. Journ. Geol. Soc. vol. 1 
(1894) p. 244. Some approach may be seen to the structure in slices of 
Zoblitz serpentine in Prof. Bouney’s collection, and a very faint approach in 
certain slices from Carn Sparnack and Lankidden (Lizard). 

4 T. G. Bonney, Quart. Journ. Geol. Soc. vol. xxxvii (1881) p. 43, & ‘Ligurian 
& Tuscan Serpentines,’ Geol. Mag. 1879, p. 366. 

5 Mr. Blake states that it is improbable that the Carboniferous Limestone 
once extended over this district, Quart. Journ. Geol. Soc. vol. xliv (1888) p. 482.. 
But in the first place, infiltration from an overlying limestone into a crushed 
serpentine is known to be the origin of some ophicalcites of this type. Secondly, 
the former extension of the Carboniferous Limestone is probable ; for, although 
the nearest point of it at the present day is about 7 miles distant, it is there in 
force and is not likely to have died out so quickly. As older limestones in this. 
district are rare and local, it is less probable that they should have furnished 


the calcite. 


Q.J.G.8. No. 218. U 


290 PROF. T. G. BONNEY AND MISS C. A. RAISINON [May 1899, 


by or intercrystallized with fibres, of actinolite(?) or serpentine, as 
already described by us in certain varioles. These associated crystals 
are possibly pseudomorphic after some mineral which contained 
lime and magnesia, and it might be, as in the varioles, a pyroxene. 
Some slices also include remnants of crystals with one close cleavage, 
and a straight extinction, apparently enstatite. Here the carbonate 
seems to creep along the cleavage-planes, but it is often difficult to 
say whether the change has been by replacement of a mineral 
in situ or by simple infiltration from without. Such replacements 
will cause the rock to become more or less a dolomitized serpentine,’ 
and this might happen without any very conspicuous structural 
change. 

A set of specimens from Felin-wen, into the details of which it is 
perhaps needless to enter, in part may be explained as above; but 
in two instances these appear to be actual limestones, probably 
Carboniferous, slightly dolomitized, veined by aserpentinous mineral 
which has every appearance of being secondarily deposited, for, 
besides certain peculiarities of structure, it occurs sometimes in 
cracks not thicker than a sheet of paper. 


LY. Oruer Intrusive Rooks. 


Of the rocks associated with the serpentine, the gabbro by its 
distribution suggests an intrusive mass, while others can be seen to 
cut the former as dykes or veins. Mineralogically, they are often 
closely connected with it. 


(1) (Pyroxenites, etc.) Diallage-rock, Enstatite-rock, ete. 


Diallage-rock.—We found this in small patches in connexion 
with several masses of serpentine, and the junction for the most 
part (especially in the least modified examples) is abrupt. Along 
the northern shore of the large inlet south of Penrhyn-Fadog it 
is visible for about 12 yards or more, in the narrow rocky footway 
along the beach. It interrupts a normal-looking serpentine, and 
can be traced along the base of the low cliff, where it forms 
branching veins. That it is intrusive in the serpentine cannot be 
doubted, and the succession is similar to that at Lendalfoot and 
other places.” The rock consists of large crystals (often 14 inch 
long) with the usual brassy lustre and well-marked cleavages, 
associated with sparse spots or small patches of a dull purplish 
serpentine. Under the microscope these prove to be small well- 
formed crystals or rounded grains enclosed in, and lustre-mottling 
the diallage; in some cases they are enstatite, in others more 
probably olivine. 


1 A whitish band, like a dyke or vein, in a crushed serpentine east of 
Pwll-pillo consists of dolomite enclosing fragments of serpentine, and is 
probably due to a crush acting on one of these dolomitic serpentines. 

2 T. G. Bonney, ‘ Serpentine, etc, of Ayrshire,’ Quart. Journ. Geol. Soc. 
vol, xxxiv (1878) p. 779. 


Vol. 55.] | SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. 291 


Enstatite-rock.—This apparently forms a dyke (12 to 18 
‘inches wide) cutting a low boss of serpentine near the northern 
shore of the large inlet south of Penrhyn-Fadog. Crystals of 
enstatite are conspicuous on an exposed surface. ‘These are about 
1 inch long, markedly idiomorphic (bounded by faces 010 and 110), 
having fresh-looking cleavage-planes (with brassy lustre) crossed by 
two sets of cleavage-lines at right angles to each other. The 
‘bright surfaces are surrounded by a dull, pale green substance, 
which indicates cross-fractured crystals. Under the microscope the 
rock is seen to consist mainly of enstatite partly altered to a faintly 
pleochroic * mineral and a steatite-like aggregate. In one or two 
cases, crystals of the one character are apparently enclosed in 
crystals of the other. A slice obtained from a rather crushed band 
shows arudely granular structure, and is traversed by brown-stained 
-eracks which often, but not always, follow the outline of the grains. 
A few small grains occur, which are perhaps perofskite. 

In the islet at the mouth of the inlet a rather more extensive 
outcrop of a similar rock interrupts the serpentine. It forms low 
reefs along the western beach of the islet, rising and broadening at 
the southern end into a considerable crag (becoming schistose in 
parts), andit just appears about the middle of the islet at the foot of 
the eastern cliff adjoining the serpentine. The microscopic characters 
are very similar to those of the rock described in the preceding 
paragraph, but one slice contains a few grains of augite, and in 
another an actinolitic growth occurs which is described on p. 291. 
Very near the islet, in a low reef at the entrance of Penrhyn-Fadog 
Inlet, is yet another enstatite-rock, probably also intrusive, but no 
junction is exposed. This, however, contains a small amount of 
intererystallized diallage. Similarly, a small intruded mass in a 
boss at Cerig-moelion is a rock now composed of serpentine and 
diallage, but microscopic examination shows the serpentine to have 
‘been formed from enstatite. 

Again, an enstatite-rock forms the point of a skerry projecting 
from the sand, near the boss first described. It is pale greenish or 
whitish, at places almost fibrous, and in the field much resembles a 
slightly crushed variety of the diallage-rock. Under the microscope, 
the slice shows a curious mottling of two constituents: one is 
ferriferous, apparently an altered enstatite ; the other is a clear 
serpentinous mineral. Some of the latter replaces a variety of 
enstatite ; the only clue to the origin of the remainder is that it 
does not show the characteristic structure of serpentine formed from 
olivine. The slice is partly crossed by a vein-like band of a fibrous 
mineral with fairly bright polarization-tints and straight extinction : 
this is probably a variety of serpentine. 

Thus there is proof of the intrusion into serpentine of (1) a 
diallage-rock, (2) an enstatite-rock, and (3) rocks formed of the two 
minerals combined in varying proportions: that is, of pyroxenites, 
using the term in a rather extended sense. Where, however, the 
enstatite has become serpentinized, especially if the rock forms 

? Markedly pleochroic in a thicker slice. 
v2 


292 ‘ PROF. T. G. BONNEY AND MISS C. A. RAISIN ON [May 1899, 


a separate boss, the question of its relation to the general mass of 
serpentine must often be left undecided, for specimens occur which 
mineralogically form transitions from both the diallage-rock and 
the enstatite-rock to the serpentine. 

Actinolite-rocks.—These have been mentioned at many 
localities, generally occurring where there is evidence of great 
crushing. Sometimes the macroscopic aspect suggests a possible 
relation to modified diallage-rocks. By microscopic examination 
we can trace in more than one place a series showing an increasing 
amount of alteration. 

(a) From south-east of Penrhyn-Fadog.—In slices of some speci- 
mens from the enstatite-rock of the islet, a secondary actinolite 
occurs. The latter mineral is occasionally scattered in fairly long 
prisms showing a streaky and somewhat tufted grouping. In one 
or two places it seems to be in connexion with granular patches of 
augite. A pale greenish-grey rock, with remains of greenish crystals,. 
comes from the low reef immediately tothe north. Microscopic 
examination shows this to consist of fragments of diallage-crystals 
interspersed with matted actinolite. A rock adjoining this is. 
markedly schistose, with thin crumpled whitish lamine in a dull 
grey mass; but the microscopic constituents are similar, though 
more altered. 

(6) From the beach south of Fadog.—Three rocks sliced for 
microscopic examination probably represent an irregular outcrop of 
a mass or dyke, which doubtless was originally some form of 
pyroxenite. One of these specimens is crushed and crumpled, 
white and glittering with small crowded crystals. Microscopic 
examination shows the ruins of crystals in bad preservation, appa- 
rently diallage, shattered and sometimes split, with long narrow 
actinolite-crystals scattered about. Between all these we find as a 
groundmass, sometimes a tangle of small actinolites, sometimes: | 
a clear colourless mineral, with one strongly marked cleavage, and 
bright polarization-tints, the extinction-angle being too high for a 
hornblende ; occasionally it is twinned: we regard it as a pyroxene. 
It is, then, highly probable that this specimen a a recon- 
struction of a diallage-rock. 

The three following specimens are white or greyish and 
crumpled :—(c) From Plas- céch Quarry, forming vein- or dyke- 
like bands, described on p. 297; (d) from ficlds north-east of 
Plas-céch ; and (e) from the beach south of Penrhyn-Fadog, 
apparently in veins branching from the dyke of diallage-rock 
mentioned on p. 278. The microscope shows that these might 
be called actinolite-schists, for they consist of a foliated mass of 
actinolite-fibres much crumpled, and sometimes showing strain-slip 
cleavage. Specimens d & e are seen to contain a few grains of 
magnetite, and the latter slice is slightly interstreaked with ser- 
pentine. We consider these specimens to be an extreme product of 
diallage-rock under pressure-metamorphism. 


Vol. 55.] | SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. 293 


(2) Gabbro. 


Immediately north of Dinas-bich a dyke cuts the serpentine, 
extending along the shore for about 20 yards or more, roughly from 
east to west. The mass in the field is seen to vary from a pale 
green or grey rock with small green crystals, to a coarsely holo- 
crystalline rock, apparently consisting of three distinct minerals, 
respectively dark, pale-green, and whitish. Microscopic examination 
shows in all the varieties :—(1) unaltered augite (the dark crystals 
in the hand-specimen), which in one is intercrystallized in small 
patches like a micropegmatite; (2) felspar much kaolinized (the 
above-named whitish mineral) ; (3) serpentine, somewhat abnormal, 
not resembling that derived from olivine: it sometimes shows a 
parallel structure probably due to the alteration of enstatite, and 
the relations with augite would agree with this interpretation; and 
(4) a constituent formed of small aggregated granules, dull drab in 
colour, with high refraction, and tending to an isometric outline. 
They sometimes form strings bordering the pyroxene or crossing 
‘the serpentine, often in a double cluster, as if deposited at the sides 
of a crack, or they constitute rather large patches at limited spots. 
Perhaps these represent more than one mineral. Some are clustered 
around spots of iron-oxide, and thus suggest perofskite; but a 
larger number occur along cracks in, or even replace parts of, a 
mineral like felspar, and thus are more probably garnets. The rock 
may be termed an enstatite-gabbro. 

The ordinary gabbro, as all observers have noticed, generally forms 
abrupt masses. It passes from the usual coarse structure, with 
diallage-crystals 3 inch long, to a fine-grained or even a compact 
variety. The different forms may occur in a patchy manner within 
the same large mass, as at Graig-fawr; but it is often difficult to 
identify a compact form, when it occurs in a small outcrop. 

A search along the margin of the gabbro-masses! was not rewarded 
by specimens giving a direct proof of the relations of the gabbro to 
the serpentine; this has to be inferred from the distribution of the 
_ two rocks, as seen on the map. One mass, rising like an islet from 
the marsh north-west of Llyn Dinam, is roughly oval in outline, 
about 30 feet long, nearly perpendicular on its western face, but 
sloping eastward. The mass is mainly gabbro, though a laminated 
rock is adherent on the sloping surface, apparently a dull drab- 
coloured flinty argillite. Microscopic examination shows this rock 
to consist of rather sparse lenticular streaks of a mosaic of minute 
quartz or secondary felspar, with intervening darker bands, some- 
what dusty-looking but crowded with epidote ; a minute micaceous 
mineral (?sericite) is often intererystallized in both parts. The 
streaky structure and the crumpling of veins show that the rock 
has been greatly crushed. Whether the original mass was one of 
tthe schists or a gabbro it is not possible to say. 


* Specimens from two localities are described in § V. p. 295. 


294 PROF. T. G. BONNEY AND MISS C. A. RAISIN ON [May 1899,- 


(8) Porphyrite (?). 


A rather slaty-looking purplish rock, which somewhat resembles. 
a crushed compact porphyrite, occurs in several places among the 
schists or schistose rocks, but the rock could not be identified 
precisely without careful examination of each specimen. At one 
locality, however, north-east of Cerig-moelion, whence sections have 
been prepared, it appears to be a porphyrite. This, as described 
on p. 296, contains some peculiar tufts of actinolite. 


(4) Greenstones. 


Greenstone-dykes cutting the gabbro are well seen in several bosses. 
south of Llyn Dinam and west of Llyn Penrhyn. On one surface: 
four almost parallel dykes can be traced: the narrowest (2 inches- 


wide) compact and dull green, the broadest (about 5 feet across) 
apparently a basalt or very fine-grained dolerite (not in good 
preservation). 


Junction-specimens from another part, where the dyke is branched, . 


have been sliced. These show the gabbro with a rather uneven 
edge, and a compact opaque magma-basalt, crowded with microliths, 


and containing microporphyritic crystals, often arranged in stellate 


or other clusters: these being (1) lath-shaped plagioclase-felspar, 


sometimes reconstituted, with an aggregate structure; (2) augite ;. 


and (8) a green or brown silicate, associated with opacite, probably 
serpentinized enstatite. 

_A massive dolerite-dyke can be recognized at intervals over a 
considerable distance, as shown on the Geological Survey map. It 
cuts the serpentine of Holyhead Island and extends near the south- 


western boundary to the cottage by Plas-céch. It is doubtless con-- 


nected with the dyke of coarse dolerite near Holyhead, to which it 
bears a general resemblance. It is perhaps rather finer-grained,. 
but we have not had it sliced, as this seemed unnecessary. 


VY. AcrinoLitse-TuFts 1n Rocks NEAR JUNCTIONS. 


Slices cut for microscopic examination from several specimens, 


which are evidently near a junction of two rocks, show tufts of 


acicular crystals often diverging in opposite directions from a centre. 
Where best developed, the prisms are long and narrow (say about 
‘08 by ‘002 inch) with even sides, though they are somewhat 
jagged at their ends, and are not infrequently curved, forming 
sheaf-like groups (Pl. XXIII, fig. 6). The mineral is generally a 


clear, pale green, with the extinction and occasionally even the: 
lattice-cleavage of hornblende. The tufts traverse the rock in all. 


directions, and sometimes penetrate into veins or, where the rock 


is banded, into adjacent layers: the prisms being often interrupted. 
by inclusions of crystalline grains. Hence we deem them of 


— 


—————EeEEEEeE—eEeE—EEEisrS—“< SP 


Vol. 55.] | SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. 295 


secondary origin. They have a considerable resemblance to the 
radial growth described in actinolite-schists by one of us,’ and a 
still closer similarity to the tufts in the rocks of Bastogne in the 
Ardennes.” 

(a) In the district west of Llyn Penrhyn, we endeavoured to 
trace the junction of gabbro and serpentine, and obtained one 
specimen in which a small triangular patch resembled a tongue of 
gabbro. This, on microscopic examination, was seen to be a coarsely 
crystalline aggregate, mainly plagioclase-felspar and pyroxene, but 
the surrounding mass contained acicular tufts. The interpretation 
of the specimen is not easy, but we have come to the conclusion that 
the latter part is more probably crushed material of the gabbro, the 
apparently intrusive tongue being a piece which has escaped; for 
other fragments can be detected, and the compact rock is a confused 
ageregate, partly felspathic, which shows signs of a certain amount 
of reconstitution.? Further, in the fragmental remnant of the 
gabbro, the green constituent (doubtless derived from the pyroxene) 
seems, as it were, to grow out from the ends of the original crystal 
in acicular actinolite similar to that of the tufts. Thus the gabbro 
is evidently brecciated and crushed near the margin of its outcrop, 
and the radial tufts seem to have been developed 1 in the crushed 
material. 

(6) On the southern shore at the head of the large inlet south of 
Penrhyn-Fadog, we pass from a rather large boss of serpentine 
(quarried in the field), across a small interval. to a soft dark 
chloritic rock forming a narrow strip in the cliff. Here begins a 
large mass, mainly of gabbro similar to that of Graig-Dinas. Next 
to the chlorite-rock, however, a compact dull grey-green rock with a 
streaky structure (parallel to the margin) reminds us of the Tyddyn- 
y-cob specimens, previously described by one of us.* Under the 
microscope it presents a certain similarity to these, but is without 
residual fragments of recognizable gabbro. Tufts, however, ot 
actinolite occur, apparently similar in origin to those in the 
specimen last described, and the same explanation is probably 
applicable in this instance. 

(c) Near the crushed gabbro west of Llyn Penrhyn two outcrops 
occur, immediately south, of the small streamlet, both being at the 
northern edge of ‘green schists,’ which are well shown in a small 
quarry in the western section, and just appear in the eastern boss. 
North of both, on the other side of the water, rise masses of the 
crushed serpentine already noticed. In the quarry the pale greenish 
slabby rock with a rather gritty texture forms a low double 
anticlinal, the northern slope of which is in contact with one of the 


1 «On the Garnet-Actinolite Schists of the St. Gothard Pass,’ Quart. Journ. 
Geol. Soc. vol. liv (1898) pp. 857-871. Figs. 2, 3, & 4, pp. 36 2-363, would ' 
represent the actinolite of the Anglesey rocks, as seen under the microscope. 

2 A. Renard, Bull. Mus. Roy. Hist. Nat. Bele. vol. i (1882) ; see especially pl. ii. 

3 That pressure has acted on the rocks of this area is well shown in the 
adjacent serpentine ; see p. 277. 

* Quart. Journ. Geol. Soc. vol. xxxvii (1881) p. 41. 


296 PROF, T. G. BONNEY AND MISS C. A. RAISIN ON [May 1899, 


soft dark chloritic rocks, while a very small projecting knob consists 
apparently of gabbro. Under the microscope, the rock from the 
quarry exhibits a finely granular quartz-felspar groundmass, with 
greenish, probably actinolitic microliths, small lenticular micaceous 
patches, and occasionally a broken fragment of a large felspar-crystal. 
This rock is evidently pressure-modified, and probably is derived from 
a gneiss, the type of structure being somewhat similar to that of the 
‘mylonitic’ gneiss of Glen Laggan. In the boss farther east, in 
the same kind of rock, tufts of acicular actinolite have developed, 
smaller than, but similar to, those which we have described in 
crushed gabbros. There the tufts have doubtless formed from the 
pyroxenic constituent ; and the crushed rock before us was probably 
once a hornblendic gneiss. 

(d) The rock, already mentioned as probably a porphyrite (p. 294), 
occurs in a small field at Cerig-moelion north-west of the quarry. A 
craglet of serpentine, partly variolitic ($ II, 3 f, p. 283), rises on the 
southern slope of the field. About 3 yards from this, a low mound 
begins, on which are several small bosses of rock (1 to 3 feet across). 
The nearer of these probably consist of modified gabbro. One of 
them shows yellowish epidotic patches in a pale green ground, the 
fine laminee of which are crushed and crumpled, with a slight, rather 
fibrous lustrous speckling. Under the microscope, the epidote is 
seen to occur in aggregated granules, or in short, rather thick prisms. 
The part between the patches consists mainly of matted actinolite, 
often showing a tendency to a streaky arrangement, and at one 
place a group or crystal of (?) zoisite occurs. The rock is probably 
a gabbro modified by pressure. 

Next beyond this (in one boss to the west of the mound, and at 
the southern corner of one near the centre) is a rock containing 
abundant tufted actinolite (7 inch or more long) in a soft green 
ground, which includes (as seen under the microscope) flaky chlorite 
with some granules of either zoisite or a felspar. It is, on the 
whole, more probable that this rock is not a porphyrite, but has been 
derived from the gabbro. 

From the next few bosses (each about 3 feet broad) several banded 
specimens were obtained! The bands are:—(1)A dull pale greenish- 
grey rock, compact, but finely laminated on the weathered surface: 
on microscopic examination we see a felsitic groundmass crowded 
with granular epidote; (2) a pale greyish-purple rock, similarly 
compact and laminated, composed of a cryptocrystalline felsitic 
groundmass, throughout which are scattered very numerous but 
minute microliths of actinolite and small grains of opacite; and (3) 
a similar rock, but darker purple in the hand-specimen, rather finer 
grained in texture, and more thickly crowded with opacite. Radial 
or sheaf-like tufts of a greenish actinolite penetrate all these bands 
as in the St. Gothard schists, and the crystals are developed some- 


The next boss is composed of compact purplish rock without actinolitic tufts. 
A banded porphyrite accordingly seems to extend roughly east and west, north 
of the gabbro and serpentine. 


< wee 


OO 


Vol. 55.] | SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. 297 


times along, but more frequently across the structure-planes. The 
tufts may be as much as ‘15 inch (4 mm.) long; the mineral is 
pleochroic (green with the long axis parallel to the vibration- 
plane of the nicol, and very faintly yellowish when transverse), the 
maximum extinction-angle obtained being 14°. 

We cannot doubt that the rocks here have been greatly crushed ; 
veins or mineral streaks are crumpled ; oblique lines cross the bands, 
which themselves are probably bounded by shear-planes ; and under 
the large gabbro-mass to the west is a crushed, almost ‘ papery rock,’ 
probably representing the soft chlorite-rock described below. To 
these rocks with actinolite-tufts, the explanation put forward by one 
of us doubtless applies, namely, that the secondary actinolite has 
developed in a crushed material from an original augite or hornblende.’ 
Thus a relation exists between these rocks with peculiar actinolite- 
tufts and actinolitic rocks which have been described from other 
regions; and even in Anglesey, as we have indicated, the rocks in 
which this radial growth has occurred are not identical petro- 
graphically. 


VI. Cutorite-Rock AND TAtLc-scHIst. 


The macroscopic and microscopic characters of the dull-green 
ehlorite-rock, often containing well-formed magnetite, have already 
been described by one of us.* The slight development of the schis- 
tose structure is probably due to the uniform and soft nature of the 
rock, which was crushed rather than sheared. It is found in many 
places, generally as a narrow outcrop, most extensively at Plas-céch, 
associated, as has been described, with talc-schist. Here, west of 
the Rhoscolyn road, a small area (measuring about 150 x 100 yards) 
forms a kind of plateau; marsh or low meadow-land bounds it 
abruptly on the north, west, and south. Most of the rock is a 
schist or schistose, with lamination or banding well marked, although 
often irregular, the rock in places becoming patchy. It is frequently 
greyish-green, with dark green or yellowish streaks (epidotic), or 
with the latter colour spreading irregularly over the greyish-green 
ground. The original nature of this rock is difficult to determine: it 
may have been a gabbro or diabase, but it must be placed at present 
with the ‘green schists.’* The dip varies somewhat, but is about north 
(say, N.N.E., 35° to 40°). Thus at the quarry * this schist seems to 
overlie other rocks. 

The northern face of the quarry (now sloping at a high angle) 


1 T. G. Bonney, Quart. Journ. Geol. Soc. vol. liv (1898) p.368 & vol. xlix (1893) 
‘p. 101. It is possible that the tufted growth in the porphyrite, as contrasted 
with the confused crowding in the rock probably derived from a pyroxenite, is 
due to a more sparse or more scattered distribution of the original mineral. 

2 Quart. Journ. Geol. Soc. vol. xxxvii (1881) p.44. On p. 43, for ‘left’ of 
road, read ‘ right.’ 

8 As Prof. Bonney states in more than one place—the ‘ Griine Schiefer’ may 
be basic igneous rocks ; see Quart. Journ. Geol. Soe. vol. 1 (1894) p. 284. 

4 Situated at the south-western corner of the plateau, immediately east of the 
jpool marked on the 6-inch Survey map. 


298 PROF. T. G. BONNEY AND MISS C. A. RAISIN ON [May 1899, 


consists mainly, beneath the schist,’ of a dark green soft chlorite- 
rock. This forms several ellipsoidal masses 10 to 15 feet long, 
resembling the bolster-like spheroids of a diabase. Between these 
are irregular whitish masses or bands of a rock (closely laminated and 
much corrugated, sometimes even fibrous), consisting mainly of 
colourless actinolite. On the western side of the quarry, we find 
in the upper part similar chlorite-rock interrupted by green schist 
and by two actinolitic masses, and then, after a few feet covered 
by brambles, more rock, which is in places distinctly actinolitic.. 
This craglet terminates at the pool. 

The chlorite-schist rises as a roughly triangular boss towards 
the eastern side of the quarry.” ‘The talc-schist is still to be 
found in the north-western corner (and at the north-east) clinging 
to the chlorite-rock, but for the most part has been completely 
removed along the band B in the figure to which we have referred, 
and then is found on the eastern face. On this side of the quarry 
it extends above and beyond the uprising chlorite-schist already 
mentioned for about 20 yards, and then, towards the low flat. 
ground, small outcrops of green schist or schistose rock occur. 
These are crushed almost out of recognition (sometimes with well- 
marked strain-slip cleavage), but suggest the possibility that 
chlorite-schist, serpentine, and even the gabbro or green schist are 
all represented. 

Thus the chlorite-schist rises in the northern and the western face: 
to a height of about 15 feet, projects in the low triangular boss on the 
east, and is found at the foot of that slope; while west of the quarry, 
judging from one small boss, it may extend through the green 
schist. It may have intruded into the gabbro, into the original of 
the talc-schist, and into that of the crushed actinolitic rock. This- 
last-named might possibly be derived from a pyroxenic rock, perhaps 
the diallage-rock. 

All the rocks in the above-described section have evidently been 
much disturbed. Even the abrupt rise of the little plateau from 
the lowland, with the formation at its edge of pools and springs of 


water, suggests possible lines of fault.? The dip of the schist is- 


generally northerly, but with variations. The actinolitic rock 
(north and west of the quarry) is crumpled into small zigzags,. 
while the fibrous actinolite itself is probably an evidence of the 
effects of pressure.* Of the pressure-modification shown in the flaky 
chlorite-rock we have already spoken. The tale-schist on the eastern. 
side has, first, planes which dip westward about 44°, next curving 
planes dipping northward 70° or more ; farther on, other planes cross 
these at acute angles, in such wise that the rock is crushed into small 
rhomboids or ellipsoids as if by an attempt at strain-slip cleavage. 
This part seems to include ‘eyes,’ similar in shape and relations. 
to those which occur uncrushed in masses of squeezed serpentine.. 


1 <A’ of the original figure, Quart. Journ. Geol. Soc. vol. xxxvii (1881) p. 44.. 
2 Marked ‘ x’ in fig. 3, bid. p. 44. 

3 Compare Malldraeth Marsh for an example on a much larger scale. 

4 T. G. Bonney, Quart. Journ. Geol. Soc. vol. xlix (1893) pp. 101, 102. 


— 


Vol. 55.] | SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. 299' 


Rather towards the southern end, several of these ellipsoids or rhom-: 
boids (measuring about 6 x 14 inches) are green in the midst of 
the whitish mass. Specimens from these have been cut, and appear 
to be serpentine. In another slice (from rock of the northern 
side) small wisps of squeezed serpentine appear to remain in a 
much-crumpled tale-schist. Thus these rocks corroborate the view 
maintained by one of us,’ that the rather similar taic-schist of the 
Gornergrat was formed from serpentine by crushing and the action 
of water. 

The small plateau yields no other example of the talc-schist, 
but at the northern and north-eastern edge we find some evidence 
in favour of the intrusive character of the chlorite-rock. At this: 
part a perpendicular crag consists mainly of ‘ green schist,’ but 
chlorite-rock (here containing octahedra of magnetite) occurs for a 
height of from 1 to 2 feet from the ground. It disappears for a 
few paces, and then rises to about 10 or 12 feet. Thus the plateau 
seems to consist of ‘green schist’ with a mass of intrusive rock. 
below protruding at the north-east, and near the quarry at the 
south-west, while at the latter part some serpentine (with talc- 
schist, its still further changed representative) occurs, the intrusive 
mass (now chlorite-schist) being posterior to both gabbro or ‘ green 
schist’ and serpentine.” In the great crush, these rocks were thrust 
over and converted into schist. 

To the east, across the road, similar ‘ green schist’? is quarried ; 
it also forms the boss on which Cerig is marked in the 6-inch 
Survey map, as well as (beyond some serpentine) several large 
bosses in the next fields. These rise from the marsh on the 
south, and from marshy or low land on the north-east. On 
that side, below the large boss, in the field farther from the 
road, chlorite-rock occurs in two places, associated in one, and 
possibly in both, with crushed actinolitic rock, while a crumbling 
serpentine is just seen a few yards off in the grass. In the eastern 
boss nearer the road, we find crushed serpentine, and, about 
10 yards away in a small scarp, which is partly masked, the 
following succession :—chlorite-schist, talc-schist, chlorite-schist,. 
and ‘ green schist’ (?). 

The soft chlorite-rock has been found in other localities. One is 
among the ‘green schists,’ north-west of Plas-céch beyond the 
marsh ; a second at the head of the large inlet south of Penrhyn- 
Fadog. This has been already described (p. 297), and might be 
a narrow dyke, between gabbro and serpentine. A third is from 
north-west of Yr-ynys (west of Llyn Penrhyn), apparently here 
near the edge of serpentine. A fourth example occurs immediately 
west of Llyn Penrhyn (south of the stream), in a boss mainly 
composed of serpentine. A fifth from a boss to the west of this 


1 T. G. Bonney, Geol. Mag. 1890, p. 540. 

2 And to diallage-rock, if it occurred. 

3 The aspect in the field was suggestive of the modification of a compact 
gabbro or diabase, but here also no definite evidence was obtained. 


300 PROF. T. G. BONNEY AND MISS C. A. RAISIN ON [May 1899, 


(see p. 278) forms a narrow dyke-like mass (about 7 inches wide) 
with rather flaky structure; and under the microscope a specimen 
shows alternating streaks, marked respectively by the presence and 
absence of scattered iron-oxide.' 

This additional evidence supports the view that the chlorite- 
‘schist is probably an intrusive rock; but we are no nearer to the 
discovery of its original nature.” 


VII. Errects or PressurE; AGE oF THE Rocks, 


The results of the pressure which has acted on the schists of 
Anglesey are very familiar; but the igneous rocks which we are 
describing show similar effects. The serpentine generally is more or 
less schistose, as already shown by one of us,® some specimens even 
resembling those which have been described from the Swiss Alps.* 
‘The crushed laminez are thin, even papery, sometimes crumpled 
but generally curving, and they then bend around more compact parts. 
These form hard egg-like nodules which slip out easily from the 
coating of the schistose lamin. They may vary from 2 to 3 inches 
in length, but both smaller and very much larger examples occur. 
One has been described near the lakes about 3 feet long (p. 277) ; 
but masses much larger than this, bounded by curving schistose 
lamine, or even large patches of serpentine, have in like manner 
escaped crushing. 

The gabbro, as has been said, occurs both unmodified and 
‘pressure-modified. The latter parts sometimes consist of green 
and white, or more commonly green and yellow (because epidotic) 
elongated spots with a distinct orientation, in which condition the 
rock can be identified under the microscope. At other places it is 
difficult to decide whether the mass belongs to the green schists, or 
is a pressure-modified compact variety of gabbro. We cannot, 
therefore, be sure that in this respect our mapping is always correct. 
Still, the presence of crystalline patches or other evidence often 
‘gives some indication. 

The schistose structure in the gabbro is traceable over considerable 
areas, but is absent from others. Thus the large masses at Graig- 
fawr and Cerig-moelion have mainly escaped, while past Tyddyn-y- 
cob the rock is really a gabbro-schist. This difference may be 
partly due to the crushing along certain thrust-planes, but it is 
possible that, if the Graig-fawr and Cerig-moelion bosses represent 
the solid cores of massive intrusions, these may have resisted where 


' In certain specimens from here and from near Yr-ynys, chlorite-veins are 
associated sometimes in a brecciated fashion with patches composed mainly of 
epidote and (?) zoisite intimately intercrystallized. The rock might be akin 
tu the gabbro, but the pyroxene would be absent. Some of the structure is 
like that of mineral veins; here larger crystals of epidote have formed—the 
prisms projecting from the edge of the epidote-zoisite patches into or across 
‘the chlorite-band. 

* See Geol. Mag. 1890, pp. 539, 540, for a discussion of this difficulty. 

3 1, G. Bonney, Quart. Journ. Geol. Soc. vol. xxxvii (1881) pp. 4], 48. 

+ Geol. Mag. 1890, p. 536 ; bid. 1897, p. 114. 


ee 


a 


Vol. 55.] | SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. 301 


the marginal parts, or where more irregular and narrower intrusive 
streaks, may have given way.’ ‘The smaller outcrops or less 
important varieties of rock (diallage-rock, ete.) have either yielded’ 
or resisted in correspondence with the effects produced on the mass 
into which they intrude; but local crushing is often marked, as in: 
the actinolitic rocks already described. 

Thus all the igneous intrusions of the district, except the dykes,. 
are more or less affected by pressure, and so are anterior to it. 
They, however, are clearly not of one age, although they may 
not be separated by any long intervals of time. The order of 
succession seems to be :— 


(1) Peridotite (the original of the serpentine), into which the 
diallage-rock and the enstatite-rock very soon intruded. 

(2) Gabbro. 

(3) The original of the chlorite-rock. 

(4) Diabase or basalt-dykes not modified by the pressure which 
affects all the others. Some of these dykes may be of 
Carboniferous or a later age. 


As for the date of the structure, though there were some post- 
Carboniferous movements producing fauiting, the great disturbance 
which affected so many rocks in Anglesey and Caernarvonshire was 
post-Bala and pre-Silurian.? The action of this in Caernarvonshire 
has been discussed by Mr. Harker,* who thinks that the thrust 
there came chiefly from the south-east. In Holyhead Island and 
adjacent parts of Anglesey the general dip of the schistose planes is 
towards a northerly point, as if the thrust had acted from that 
direction. In the gabbro and the serpentine * this dip is usually ata 
low angle, but it varies and becomes higher in places, probably 
near faults. 

Beyond the fact that the peridotite must be pre-Silurian, we have 
very little clue to its date. The rocks which it apparently cuts 
are probably Archean, and the only twoin the district petrologically 
related to it are the picrite of Caemawr and that of Pengorph- 
wysfa, the former of which, according to Prof. Hughes, cuts Ordo- 
vician (Arenig) beds.’ One thing, however, is certain, that the more 
ancient rock-masses in this and other portions of Anglesey have 
undergone extreme pressure, and are comparable with those in parts 
of the Scottish Highlands and of the Alps: in other words, that 
what are now lowlands may represent the roots of a former 
mountain-chain. 


1 A man quarrying one of the large bosses stated that the rock became 
harder as he got farther in. 

2 There was, however, an earlier (Archean) set of earth-movements, for in 
the basal Cambrian conglomerate are found pebbles composed of schist or 
gneiss, which had already acquired a pressure-structure. 

3 ‘Bala Volcanic Series of Caernarvonshire,’ 1889, p. 113. 

4 We think, however, that, as mentioned on p. 289, this rock is locally 
affected by a post-Carboniferous movement. 

5 T. G. Bonney, ‘On the so-called Diorite of Little Knott, with further 
Remarks on the Occurrence of Picrites in Wales,’ Quart. Journ. Geol. Soc. 
vol. xli (1885) p. 515. 


302 PROF, T. G. BONNEY AND MISS C. A. RAISIN ON [May 1899, 


EXPLANATION OF PLATE XXIII. 


Fig. 1. x 17. Varuiolitic serpentine from the point north of Penrhyn-Fadog, 
south of Four-mile Bridge and west of the Strait (p. 286). Ground- 
mass of serpentine with meshwork-structure (derived from olivine). 
Traversed by a crack filled with fibrous serpentine. 

Fig. 2. x 14. From the same slice as No. 1. A variole, embedded in serpen- 

tine, consisting of needles of colourless actinolite, embedded in a grey 
dusty -looking carbonate, as described in the text (p. 287.) 

Fig. 3. x 16. From the small quarry of serpentine north of Graig-fawr (p. 286). 
A groundmass of serpentine (left blank in the figure), crossed by 
irregular veins or bands, mainly a carbonate, but including a very few 
scattered fibres of (?) serpentine. The variole consists almost entirely 
of a dolomitic carbonate, showing radial and concentric structure. 
Fibres of serpentine or actinolite are more abundant in the marginal 
part, especially in some of the narrow concentric bands. 

Fig. 4. x 22. Variolitic serpentine from the beach south of Graig-fawr (p. 281). 

The groundmass is a pale yellowish-green, uniform-looking serpentine. 
The abundant varioles consist externally of colourless fibres, as in 
fig. 2, but a similar acicular mineral is more abundant in the dusty- 
looking carbonate of the interior, and these sometimes cross at rather 
definite angles, as is shown to some extent towards the lower boundary 
of the drawing. 

Fig. 5. x 22. From a boulder of bastite-serpentine near the north-western 
end of Graig-fawr (p. 288). Part of a large crystal of bastite, lustre- 
mottled, with rounded grains. It shows a parallel fibrous structure, 
but a confused aggregate polarization. The darker shaded part of the 
enclosed grains is a pale green serpentine, the colourless exterior being a 
flaky actinolite, often piercing into the serpentine; these minerals are 
generally parallel one with another and with the structure in the bastite. 

Fig. 6. x 16. North-east of Cerig-moelion (?a crushed banded porphyrite), 
p- 296. A confusedly cryptocrystalline groundmass, the clear patches 
being apparently a chalcedonic mosaic traversed by interrupted, roughly 
parallel lines of ferrite. The lower part of the drawing shows the 
edge of one of the blacker bands. The tufts are an acicular hornblende, 
as described. 


DiscussroN. 


Gen. McManon said that he had listened with great interest to 
the lucid exposition of the paper by Prof. Bonney, and looked 
forward to its study when it appeared in print. An important 
paper containing so many details could not be satisfactorily discussed 
prior to such study. He asked whether he had correctly understood 
the Authors to imply that the spherulitic structure of the ‘ vario- 
litic’ serpentines was due to secondary aqueous agents. Some 
minerals and salts deposited from solution in water assume the 
radiating and concentric structure of spherulites, and the fact that 
those described by the Authors consisted in part of carbonate of 
iron seemed to imply an aqueous origin. 

Prof. Sorzas ventured to express his admiration of the courage 
and success with which the Authors had attacked the difficult 
problems involved in the study of these obscure rocks. The accom- 
panying chemical analyses were most welcome; the centre of 
interest in petrology seemed likely, in the near future, to shift from 
the microscope to the laboratory; and evidently some reform was 


Quart Journ Geol, Soc Vol LY Pl xx, 


FH Michael del. et Hth. Mintern Brosimp. 


VARIOUITIC SERPENTINES,ETC. 
‘ FROM ANGLESEY. 


Vol. 55.] SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. 303 


necessary when obvious andesites and basalts, or andesites and 
trachytes, were found to possess an almost identical chemical com- 
position, or when good quartz-diorites were found to vary in the 
amount of silica which they contained to the extent of 22 per cent. 
The speaker had seen in the field some of the rocks exhibited, and he 
noticed a resemblance between the Tertiary gabbros of this district and 
those of Carlingford ; in some Irish localities the Tertiary gabbros 
were as perfectly mylonized as those in Anglesey, and it seemed 
possible that the excessive deformation of the more ancient rocks 
might be due to the repeated earth-movements from which they had 
suffered. The spherulites in the pyroxenic constituents described 
by the Authors occupied precisely the same relative position as 
grains of olivine in the pyroxene of a gabbro from Slieve Foze. 

The Rev. J. F. Brake said that he was glad to be able, on this 
occasion, to appreciate the value of the Authors’ work. From what 
he had seen of the area he had been convinced that it would repay 
a more careful examination than he had been able to make. The 
present contribution was a great step in advance, particularly in 
the matter of the spherulitic variety, of which the speaker had 
known nothing. He enquired whether this variety was more 
abundant near the edge of the mass, so as to suggest that differences 
of cooling might have caused it; also whether the dykes or bands 
of enstatite or diallage might be infiltration-veins ; and he remarked 
on the sporadic nature of the squeezing of the serpentine, some 
parts being mylonized and others merely broken. 

Dr. J. W. Greeory congratulated the Authors on this important 
contribution to the knowledge of the peridotites of the Irish Sea 
area. He thought that the Authors’ suggestion that the spherulites 
in the serpentine are not primary structures was probable, from the 
nature of the spherulites themselves: for the hollow concentric- 
shelled spherulites, such as that shown on the last of the spherulitic 
slides, are probably due to secondary changes. Gen. McMahon’s 
suggestion introduced a process which had been advocated by 
Prof. Stefani, who explained some of the North Italian spherulites 
as due to accretion and not to spherulitization. 

Mr. Greeny, Dr. Hicks, and Prof. Srezny also spoke. 

Prof. Bonney, in replying, stated to Dr. Gregory that he held the 
varioles to have been developed in their present position, but not 
to have always possessed the spherulitic structure; te Dr. Hicks, 
that he was well aware that pressures had acted in pre-Cambrian 
times, but thought that the post-Ordovician pressure had been the 
cause of the structures mentioned in the paper. As for the occurrence 
of Pebidian schists, if the St. David’s rocks were to be taken as types 
of Pebidian, then those mentioned in the paper had no claim what- 
ever (on lithological grounds) to be called Pebidian. To Mr. Blake, 
he stated that the variolitic serpentine generally occurred near the 
northern margin of the mass, but that as the radial structure was 
not supposed to be original, the argument from spherulites would 
not apply. At the same time, the structure which the Authors 
supposed to have preceded the spherulites often did occur near the 


304 SERPENTINE AND ASSOCIATED ROCKS IN ANGLESEY. [May 1899. 


exterior of amass. The origin of the dykes of enstatite-rock and 
diallage-rock had been carefully considered, and for reasons given 
the Authors were convinced of their intrusive character. As regards 
the somewhat local character of the crushing, that was undoubtedly . 
true of Anglesey as of other regions of great earth-movements, 
Serpentine often exhibited this peculiarity in the Alps: he thought 
probably because, as the rock was brittle, the outer part gave way 
and saved the rest. To Prof. Sollas, he replied that he also had 
been often struck with the similarity of igneous rocks of different 
ages, and it was very true of serpentines, He could not believe it 
possible that pieces of glass could have been preserved in a hole- 
crystalline peridotite. He fully agreed in the importance of chemical 
analysis, but thought it of minor value where, as in this case, rocks 
had been greatly altered. To Prof. Seeley, he pointed out that the 
sharply-defined boundary of the spherulite would be consistent with 
almost any theory of its origin; and in answer to Gen. McMahon’s 
request for a theory of the origin of the varioles, he briefly 
summarized that which he had given in his outline of the paper. 


du 
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Proceedings of the Geological Society, Session 1898-1899, inclu ding the procautaens 
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of the Adjacent District to the West. (Plates XIII-XV.) 


9. Mr. Frank Rutley on Felsitic Layas and Tuffs near Conway 


10. Prof. J. B. Harrison & Mr. A. J. Jukes-Browne on the Oceanic Deposits of 
UPTUITGA Foes crcpie's ese Wec ces ona dda ogscGess vols) a «nis da mieee Vome sk’ kates an 177 


1]. The late Joseph Thomson on the Geology of Southern Morocco and the 
Atlas Mountains 


SRP SEEH THEE HE HEE ESE ESE SETHE HEH OEH SHE TES HEEE HEHE ET ESHETESEHEE HEE EEE EEE EES 


12. Dr. G. J. Hinde on Radiolaria in Chert from Chypons Farm, Mullion 
fy, MONCH at CEILS OV Ls HS Oh Yio cotec es osgereed fes.s teseg tek ee ee 214 


13. Mr. S. S. Buckman on Gravel at Moreton-in-the-Marsh. (Abstract.) ......... 220 
14. Mr. A. E. Salter on Pebbles of Schorl-rock in Drift-deposits. (Abdstract.) ... 220 


15. Mr. H. H. Arnold-Bemrose on the Geology of the Ashbourne and Buxton - 
atlwsy.-( Pintes XV ELT d& MV ILL. jecivs ssc ack ocd beta is ded onoeecoque nee 


16. Mr. H. H. Arnold-Bemrose on a Sill and Faulted Inlier in Tideswell Dale 


(Phat RU WG) sk Sie facies ik ee a 

17. Miss J. Donald on the Genera Ectomaria and Hormotoma. (Plates XXI & 
BMGT ) isis stn it's roan a Sorin vag ey x wavlg « Sualec s¥ORs se ADDS CER RE Deeg OSA noe Cane dale dian Seen 251 
18. Prof. G. A. J. Cole on the Age of certain Granites in Tyrone and London-_ 
LGR ya Boh Ne ers Clee eh ie AeA ca Rak eal Gate IA REY on Tee ee cea se a eee ows 
19. Prof. T. G. Bonney & Miss OC, A. Raisin on Varieties of Serpentine and 
Associated Rocks in Anglesey. (Plate XXTIT.) ..........cecceccecseceeceecaeeaveee 276 


[No. 219 will be published on the 1st of next August. | 


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Vol. 55.] THE CHALK AND DRIFT IN MOEN AND RUGEN. 305 


20. Retations of the Cuatx and Drirt in Moen and Rieun. By 
Prof. T. G. Bonney, D.Sc., LL.D., V.P.B.S., F.G.S., and the 
Rey. Epwin Hitt, M.A., F.G.S. (Read March 22nd, 1899.) 


ContTENTS. 
Page 
ee imtroOdUchiGn..) 0.255.442 ee ee eee 305 
II, The Chalk and Drift in Moen ............ 306 
III. The Chalk and Drift in Rigen ............ 311 
VERO OMCIISIONS:. 5.00503 be, aaesince el sacha eee BPA 


I. Iyrropvcrtion. 


Méen, one of the Danish islands, lies on the south-east of Seeland ;. 
Riigen, belonging to Germany, is very near the northern coast of 
Pomerania. They are separated in a north-westerly to a south- 
easterly direction by about 35 miles of sea, and on clear days are 
visible one from the other. Both districts have been for long—one 
of them more than half a century—classic ground in the annals of 
glacial geology. Our past work in England and elsewhere had. 
made us for some time anxious, if only for comparative purposes, to. 
undertake a personal examination of sections so diversely inter- 
preted, and an opportunity of gratifying this desire occurred last 
summer. We first visited Moen, and about a fortnight later landed 
in Rigen, remaining in each a sufficient time to examine all the 
more important sections, with the results which will be found in 
this paper. 

The ground in each island is generally low, but it becomes more: 
undulating towards the east, and rises on that side into a range of 
Chalk-downs capped with Drift and covered by beech-woods. Each 
of these tracts ends abruptly in a line of lofty Chalk-cliffs, and 
these, in both cases, exhibit at many spots that rock and the Drift 
in relations which are peculiar and abnormal. 

Many geologists have examined the islands and published explana- 
tions of the phenomena which they present. Some maintain that the. 
Glacial beds have been included in the Chalk by a series of acute 
folds ; others, that these beds have been dropped down into the Chalk 
by a series of faults. Both parties attribute the mutual relations of 
these strata, so widely separated in age, to terrestrial movements,. 
and we may quote, in this connexion, the names of Forchhammer, 
Puggaard, Lyell, Cohen & Deecke, Berendt, and H. Credner.' 


1 Forchhammer, Poggendorf’s Annal, vol. lviii, p. 626; Puggaard, ‘ Méens. 
Geologie, Copenhagen, 1851; Lyell, Trans. Geol. Soc. ser. 2, vol. vy, pt. i (1837) 
p. 252 & ‘ Antig. of Man,’ 4th ed. (1873) ch. xvii, p. 887; Cohen & Deecke, 
Mittheil. d. Naturw. Vereins f. Neupommern u. Riigen, 1889; Berendt,. 
Zeitschr. d. Deutsch. Geol. Gesellsch. vol. xli (1889) p. 148; H. Credner, ibid. 
p- 365. 


Q. He G. S. No. ZG. Xe 


3506 PROF. T. G. BONNEY AND REV. E. HILL ON THE [ Aug. 1899, 


A third group, including Johnstrup, J. Geikie, and Struckmann,* 
regard the association of the Chalk and the Glacial deposits as a 
result of ice-action. Each author, as a rule, gives cogent reasons 
for not accepting the views of his predecessors. Most, however, 
seem to have visited only one of the islands, and none to have 
given equal attention to both. 

Besides the objections, generally weighty, which may be found 
in the writings to which we refer, we may note at the outset one or 
two of a more general character. Simple faulting is insufficient; 
the Moen sections require dislocations which have turned over or 
on to their sides solid blocks of Chalk 400 feet high. In Moen the 
folds in the Chalk have in general an east-north-easterly and west- 
south-westerly strike ; in Riigen they run more nearly north and 
south. If, then, these structures are due to earth-movements, 
they must have taken place in directions almost at right angles one 
to another; if, on the other hand, these structures are due to 
the thrust of a Scandinavian ice-sheet, there must have been the 
same difference in its movements in the two districts.” Johnstrup 
seems to regard the action of the ice as somewhat similar to that 
of a ploughshare in a furrow ; but, as will be seen, it is not easy to 
locate the furrow. 

The Chalk in both islands is rather soft, very white, and, so far 
as we saw, belongs to the zone of Belemnitella mucronata. The 
flint is very like that in the Upper Chalk of England, being com- 
monly almost black, with grey spots or patches, but it occurs 
perhaps more often as lines of nodules than as continuous bands. 
The Drifts, however, exhibit some varietal differences which will be 
best indicated by giving separate descriptions of the two islands. 


Il. Tar Cuark anp Deirr iw Moen. 


Moen is parted by shallow, island-studded straits from the south- 
eastern end of Seeland, and from the north-eastern end of Falster. 
Its extreme length, from west-south-west to east-north-east, is about 
18 miles, its western coast-line beingirregular. The Drift-covered 
Chalk-downs, as already mentioned, form the eastern end of the island, 
but they die away shortly before reaching its southern extremity. 
The most interesting part of the coast is from the vicinity of Lise- 
lund (a pleasant halting-place) southward to near Hundevcengs- 
gaard, a distance of about 33 miles, in which we examined the 
cliffs both from above and below. We also walked northward from 
Liselund for some 2 miles along the beach, but in this part saw 
little of interest. Here the slope is much masked by woods, but the 
usual grey, stony clay may be detected, and we thought that it 


1 F. Johnstrup, Zeitschr. d. Deutsch. Geol. Gesellsch. vol. xxvi (1874) p. 533; 
Struckmann, ibid. vol. xxxi (1879) p. 788 ; F. Wahnschaffe, bcd. vol. xxxiv (1882) 
p. 593; J. Geikie, ‘Great Ice Age, 3rd ed. (1894) ch. xxix. 

2 It may be added that Stevns Klint, a promontory about 25 miles north of 
Moen, in the direct track of any Scandinavian ice-sheet, and presenting also a 
‘Chalk-cliff to the east, is described as not showing any of these phenomena 
(Puggaard, ‘ Moens Geologie,’ p. 50, note). 


Vol. 55.] CHALK AND DRIFT IN MOEN AND RUGEN. 307 


included in one place a boulder of Chalk about 2 yards in diameter, 
perhaps also another. 


The Drifts of Moen form two divisions. One is a stratified, more 
or less clayey sand, occasionally passing into gravel, the latter 
being often coarse and irregularly bedded. It is distributed un- 
equally over the uneven surface of the Chalk, being nearly or quite 
absent from the higher parts, but attaining sometimes a thickness 
of a few yards in the hollows. This deposit has often shpped down 
over the face of the Chalk-cliffs, but is never, so far as we could 
see, interstratified with that rock. The second division is a dull 
grey, slightly sandy clay, containing stones. It underlies the other, 
and is apparently much more local in its occurrence, being the deposit 
which is more or less intercalated with the Chalk. Among the 
stones we recognize the following materials: chalk, small and not 
abundant, except very locally ; flint rounded and subangular, from 
very small up to 8 or 9 inches in diameter ; granitoid rocks, seldom 
exceeding 1 foot in diameter; quartzite or hard sandstone (rare); 
dark-coloured compact rocks, some, perhaps, a rather hard limestone, 
some possibly an argillite. They are generally well rounded, and 
the majority of the pebbles vary from the size of a small hen’s egg 
downwards. Larger, however, occur, and these are sometimes 
striated. Boulders of Scandinavian rocks, often a yard in diameter, 
but sometimes ranging up to about 5 feet, lie on the beach, and are 
dotted about inland. No doubt they occur in the clay, but we did 
not happen to meet with a case of which we could be certain. 

Our descriptions of sections, both here and in Riigen, will be 
arranged, not in topographical order, but as they seem to throw 
light on the problems solved. 

(1) The sketch on p. 308 (fig. 1)—taken from the beach (perhaps 
representing Forchhammers Pynt)—-shows the relations of the grey 
Boulder Clay and the Chalk. It gives an oblique section of a fold 
in the latter which is plunging in the general direction of the sea, 
and exhibits a small wedge-shaped inclusion of the grey Boulder 
Clay with the lines of nodular flints dipping down, at last almost 
at right angles to its upper surface." The remainder of the 
cliff probably consists wholly of Chalk. A second section, some 
distance removed (? near Maglevands Pynt), shows an inclusion of 
the usual clay, which again is not conformable with the folding’ 
in the Chalk, and is suggestive of the infilling of a gully. 
Again, in a third section, occurring by the beach north of the 
path to a restaurant, under Dronningstolen, we see the usual grey 
pebbly clay, dipping at a moderate angle in a northerly direction. 
Here the upper surface of the clay is more nearly parallel with the 
layers of flint in the Chalk, but the junction of the two rocks is 
irregular, and the former for the last 6 inches or so is streaked 
with thin seams of powdery chalk. 


‘ Probably the case represented by Lyell, Trans. Geol. Soc. ser. 2, vol. v, pt. i 
(1837) fig. 10, p. 255, but he omits the flint-bands in the part above the clay. 


Mee 


308 PROF. T. G. BONNEY AND REV. E. HILL oN THE [ Aug. 1899, 


(2) In the cliffs near Taleren, which are fully 300 feet high, 
a grey earthy clay is seen from the beach apparently occupying 
a nearly vertical cleft or gully in the Chalk, which reaches down to 
the sea-level. Higher up the cleft opens out into a ravine, which 
seems to be partly filled with a grey chalky earth, but this may be 
only a ‘ wash-over ’ of a comparatively small portion of that material 
from above. Viewing this ravine from the top of the cliffs, we saw 


Fig. 1.—Section at Forchhammers Pynt (Méen). 


Se SS ee 
— SPF PO" EG Se 


1 = Chalk (the wall at the base is about 7 or 8 feet high). 
2= Clay. 3 = Talus, mostly made up of Chalk. 


[The sketches throughout do not profess to be more than diagrams. Flints 
were inserted only where they were distinctly seen, being often hidden by a 
wash of Chalk or Drift: hence the interruptions to the bands. | 


on the northern side, about halfway down, some fragments of the 
clay occupying a hollow in the Chalk. The surface of the Chalk 
plainly curved over the grey clay, and the hollow occupied by the 
latter obviously was not connected with the folding of the Chalk 
indicated by the bands of nodular flints, but subsequent to it. Other 


Vol. 55.] CHALK AND DRIFT IN MOEN AND RUGEN. 309 


fragments of the clay were seen low down on the southern side of 
the gully. 

(3) Confirmatory evidence is obtained from another section (fig. 2) 
south of the last, and in the neighbourhood of Sandskredsfald. 
Here we see the grey clay lying ina similar manner, but more hori- 
zontally, beneath an overcurving mass of Chalk, and here also the 
flexures in the latter are not directly connected with the common 
surface of the two. 


Fig. 2.—Section in cliffs near Sandskredsfald (Méen). 


y aA 4 
iN Ne see 


\ ay yw ee \ 

a) At Rita 
gt «yi iy S es 

au ng Dea 3 


Ve: 
cil it aon’ Me 
My Nia : 


1 = Chalk. | 2’ = Hollow in Chalk, from which 


the clay lds fallen. 
2 = Clay. = Slopes, overgrown. 


The foregoing sections may suffice as examples, but others yielding 
similar evidence could be produced from our note-books.’ The result 
of our examination of this part of the coast may be summarized in 
the followiag clauses :— 

(a) The Chalk dominates vastly over the clay. Along the beach 
it may be traced almost continuously, and sometimes for over a 
furlong without interruption even from a slip: the clay often being 
a very limited and local phenomenon. 

(6) The Chalk, above or below the clay, is generally rotten and 
stained yellowish-brown for a few inches (seldom more than 6), 
and for about the same thickness tiny streaks of chalk occur in 
the clay: this banded clay being occasionally squeezed up into 
hollows in the Chalk, 4 or 5 inches deep. 

(c) The clay very often appears to form a mere facing to the 
Chalk, or to fill a semicylindrical or wedge-shaped cavity in the 
latter, the Chalk beyond this cavity being perfectly continuous. 


1 Such as that figured by Lyell, Trans. Geol. Soc. ser. 2, vol. v. pt. i (1837) 
fig. 8, p. 254. 


310 PROF. T. G. BONNEY AND REY. E. HILL ON THE [ Aug. 1899, 


(d) The clays seem to be often associated with ravines which are 
more frequent in the upper part of the cliffs; only about three times. 
could we be certain that they reached the shore, and there is nothing 
to suggest that in any case they are prolonged much below the sea- 
level. The clays show no signs of stratification. The Chalk is 
sharply folded, but, though it and the flints were sometimes a little 
broken, we were unable to find any satisfactory evidence of faults. 
of real importance, or to connect them, if such exist in any degree, 
with the intercalations of the Drift. 


Not many localities possess such a monograph as Puggaard’s 
‘Geology of Moen.’ The three plates in which he gives a panorama 
of the coast-line are admirable for their beauty and fidelity. But, 
at the time when he. worked, the conception of folding under lateral 
pressure had scarcely, if at all, been formed. The only actions 
known to him were elevation or subsidence, and volcanic eruption, 
of which he rightly rejects the latter. He describes as one of the 
phenomena that beds which are horizontal at the cliff-top often 
dip steeply at the beach-level, and instances a portion of his 
illustrations, which depicts accurately a simple arch of the bedding- 
planes as shown by the layers of flint. Studying the panoramic 
plate which he publishes as his interpretation of the section, we 
rather doubt whether he fully allowed for the local slips so common 
in such a cliff-face. We had with us a rough copy of the plate, and 
were not seldom uncertain whether we had rightly identified our 
position. The sea, however, has gained on the land since Puggaard’s 
time (1851), and some of the inclusions of clay may have been 
largely or even wholly destroyed; in fact, this peculiar association 
of Drift and Chalk appeared to us to be restricted to the neighbour- 
hood of the present cq@st-line. 

Johnstrup rejects Puggaard’s hypothesis of depression and 
elevation, and advocates instead that of the thrust of an ice-sheet ; 
but his own figures (made when, as he says, the sections were 
especially favourable for observation) strongly suggest that the 
Drift occupies fissures or gullies in the Chalk (and in one instance 
pipes and hollows). His diagram, on a larger scale, of the inclusions 
at Forchhammers Pynt seems to prove that the Drift there is not 
infolded. These figures, showing a series of nearly parallel steeply- 
dipping sections of Drift, if interpreted on Puggaard’s hypothesis, 
demand a very peculiar kind of step-trough faulting; while his 
own hypothesis, that large masses of Drift-covered Chalk were 
overturned by the lateral thrust of an ice-tongue advancing along 
a hollow, is difficult to reconcile with the existence of a wall of 
Chalk, as shown on Puggaard’s plates, in the position of the hollow 
which he appears to postulate. One or two other difficulties 
attend Johnstrup’s view, but these can be more conveniently dis- 
cussed after we have given a description of Riigen. 

We speak throughout of the Drift intercalated with the Chalk as 
a single deposit, because, we were unable, in any of the sections 
which we could actually touch, to identify the band of sand described 


Vol. 55.] CHALK AND DRIFT IN MOEN AND RUGEN. 311 


by Puggaard as of general occurrence low down in the Drift. That, 
however, may be sometimes present, for the sections (at the time of 
our visit) evidently were not in so good a condition for examination 
as when they were studied by him. Indeed, we confined our attention 
to a comparatively small number, because the evidence of so many 
was untrustworthy, owing to staining and slip. But in the rest there 
seemed no probability of anything occurring more favourable to the 
hypothesis of faulting—or, indeed, of ice-thrust—while the testimony 
of every clear section appeared to us irreconcilable with either 
of them. 


IIl. Tae Cuarx anp Drirt in Riieun. 


The island of Riigen in many respects is a repetition of Moen, 
but on a larger scale horizontally, for its area is about 337 square 
miles. Its coasts are very conspicuously indented, and it is almost 
severed by the curiously irregular inlet called the Jasmunder Bodden. 
These features suggest that the level of the whole region was once 
higher by at least some yards. West of the Jasmunder Bodden the 
district, so far as we saw, lies low; east of it the undulations 
become more pronounced, forming gently-rolling hills of Chalk, 
which are frequently overlain, at any rate on their lower slopes, by 
sand or a sandy clay. These, on approaching the eastern coast, 
rise into elevated downs, often more than 300 feet above the sea.” 
This upland zone extends from near Sassnitz to Lohme, a distance 
of about 6 miles from north to south, and terminates on its 
eastern side in steep cliffs or slopes overlooking the Baltic. The 
cliffs of Rigen are slightly higher than those of Moen, the crest of 
that at Stubbenkammer being 435 feet above the sea, but to award 
the palm of beauty would be no easy task. 

We examined the coast from Dwasieden, a park about | mile west 
of Krampass-Sassnitz,* to Stubbenkammer—a distance altogether of 
about 7 miles, or fully twice the length of the important part 
of Moen,—passing over most of it at least twice. As the sea 
occasionally washes the base of the Chalk-cliffs, they can be 
examined continuously only from above; but wherever the descent 
was practicable and the sections were promising, we looked at them 
also from the shore. ‘The line of coast about Sassnitz trends in a 
north-easterly direction, then runs for some miles almost due north, 
and finally, before reaching Stubbenkammer, begins to work round 
to the westward: hence we saw one section (the longest) parallel 
to the general direction of the range, a second oblique to it, and 


1 A brownish band, a few inches thick, frequently appeared at the base of 
the clay, but this proved, in the cases where we could examine it, to be merely 
an iron-staining, generally of rotten Chalk. 

? We refer only to the nearly insulated part between Prorer Wick and 
Tromper Wick, bays separated the one from the Kleiner Bodden, the other from 
the Grosser Bodden by a narrow isthmus. 

® These were separate hamlets, but are now practically united in one 
rapidly-growing watering-place, collectively spoken of as Sassnitz. Krampass 
was the westernmost of the two. Soon they will be like Hastings and 
St. Leonards, 


312 PROF. T. G. BONNEY AND REV, E. HILL ON THE [Aug. 1899, 


part of a third also oblique. In addition, we made a partial 
examination of the district inland to the north of Krampass-Sassnitz, 
and obtained some idea of the coast of Prorer Wick during an 
excursion by steamer to Gorenz, south of Jasmund; this shore-line 
is at first fringed with sand-dunes, but after Binz, where the coast 
turns sharply eastward, the ground rises from the sea in steep 
slopes or even cliffs, which, so far as we could ascertain, consist 
wholly of Drift. 

In the Stubnitz district the Drift associated with the Chalk 
is less simple than that of Moen, for it consists of stony clays 
and well-bedded sand. The latter, as will be seen, has a clay-bed 
both above and below it; but away from the coast sand seems to 
be more commonly the deposit that underlies the surface-soil. 
This, however, may be a later deposit ; but we did not minutely 
investigate that question, as it had no direct bearing on the subject 
of our enquiry. 


We notice first two sets of sections which stand rather apart 
from the others :— 

(a) That seen in a cliff, some 20 feet high, between the eastern 
wall of the grounds of Schloss Dwasieden and the western end of 
Krampass, which reminded us of phenomena exhibited near Cromer. 
Here we find, as we walk towards the east, first a sandy clay con- 
taining some stones, underlain by sand which rises from the shore 
till it occupies the whole cliff. This sand is very irregularly bedded, 
and contains streaks and ‘ pockets’ of gravel, often fairly coarse. 
Next, streaks and a few boulders of Chalk make their appearance in 
it, most, if not all of them, being reconstituted. The largest piece © 
is 4 or 5 yards long, and about as many feet thick. The bedding 
of the sand, which previously was little disturbed, now becomes 
much contorted, and at one place, close to the fragments, is bent up 
into a puckered arch, just as might be seen in the Contorted Drift 
at Cromer. After an interval, in which both stony clay and bedded 
sand are exposed, a mass of Chalk rises steeply from the shore. 
As that rock can be seen glimmering for some distance through the 
shallow water, and it is certainly im situ not far away inland, we 
think that this also is probably not a boulder.! 

(b) A bedded sand, as already mentioned, frequently underlies the 
surface-soil in the southern part of the forest between the eastern 
coast and the road to Stubbenkammer. We examined three pits 
opened in this material. One (about 1 mile north-east of Sassnitz 
and a couple of furlongs from the coast) affords a clear section of some 
20 feet of sand above a talus of the same material. The sand is 
well laminated, in one or two places distinctly false-bedded, ranging 
from fine to coarse, and including one seam of the latter about 
18 inches thick : this contains a few pebbles, one or two of which 
are quite 1 inch in diameter, though the majority are smaller. The 
bedding, however, though generally so regular, is almost vertical, 


1 Further examination is then prevented by a wall. 


Vol. 55. CHALK AND DRIFT IN MOEN AND RUGEN, 313 


the strike being about north-north-west and the inclination, if any, 
to the eastern side. But a second pit, perhaps 3 mile away inland, 
shows similar sands lying almost horizontal. A third pit, imme- 
diately east of the Stubbenkammer road and a short distance from the 
southern edge of the forest, ijarger but not deeper than the first, gives 
sections of similar sands, which,however, contained a long ‘ pocket’ 
of rather angular flints, with pebbles of chalk (small and few) and 
of Scandinavian rocks up to about 1 foot in diameter. Here the 
bedding has a very slight easterly dip, but on that side of the pit it 
seems to become somewhat steeper and to be twisted rather towards 
the north. A little fine rubble underlies the turf in one or two 
places, and larger boulders (Scandinavian rock) are seen on the floor 
of the pit." This sand probably is of later date than the one inter- 
bedded with the clays, belonging, as we infer from the geological 
map by R. Lepsius, to the Oberdiluvium, and correspondiag with 
‘that mentioned in our description of Moen; but in any case the 
marked change in the angle of dip is significant. 


We come next to a group of sections which are important, as they - 
indicate the mode in which the Drift occupies cavities in the Chalk. 

(a) The first is exposed in the cliffs, here about 30 feet high, on 
the north side of the bathing-place at Sassnitz. Here we find 
a very irregular cavity in the Chalk, which spreads out hori- 
zontally to an extent of about 12 yards and cuts across the layers 
of flint. It is filled with Drift-material, varying from clay to sand, 
and containing two or three boulders. In this neighbourhood the 
halk is much bent, and probably some small thrust-faults occur, 
-which, however, produce no appreciable effect on the mass as a 
whole. A somewhat similar filled-up cavity of smaller size may be 
found north of the Kielerbach. . 

(5) The following sections were observed in pits on the slope 
‘between the southern border of the forest and the road leading 
eastward from Sassnitz. Probably these are almost due north of 
‘the last-named section. The Drift hereabouts seems generally thin, 


1 These had probably been lying on the surface (where they certainly are not 
aincommon), for none like them were seen in the sand. 

2 We have examined under the microscope specimens of the sand from the 
pit in the wood near Sassnitz and from that between the clays (Wissowerbach). 
The former consists mainly of quartz (a few grains composite), some felspar 
(including microcline and plagioclase), a few fragments of a pyroxenic mineral 
(probably hornblende), zircon, glauconite, biotite (?), garnet (?), fragments of 
alcareous organisms (rather worn), a small rotaline(?) foraminifer, a few 
opaque grains, some possibly cherty. The latter, besides the dominant quartz, 
contains felspar (not generally showing twinning), a little hornblende, tourma- 
line, zircon, rutile (?), white mica (?), garnet (?), chlorite (?), some opaque grains, 
and a few of organic origin, as before. In both cases the structure in the last 
is very indistinct, and they are probably derived fromthe Chalk. In the former 
specimen the grains appear to be slightly more rounded, but the most marked 
difference is in size. Here they commonly measure about ‘02 inch in diameter, 
hardly ever exceeding ‘033 inch, but with a good many less thaa the average. 
In the Wissowerbach specimen they are more uniform, the average being about 
005 inch. It would not be safe to generalize from single examples, but the 
difference accords with the impression formed in the field. 


314 PROF. 'T. G. BONNEY AND REV. E, HILL ON THE [Aug. 1899, 


and cannot always be identified. Most of it is sand, but clay seems 
to occur in patches.’ 

Near the edge of the wood, on the slope north of Sassnitz, is 
a rather large double pit® divided by a kind of isthmus of Chalk. 
At the top of the upper pit this rock is covered only by soil, but 
before long sand begins to intervene, and on reaching the partition 
becomes quite 8 feet thick. It is banded by more clayey layers, 
browner in colour, and an inch or so thick. The wall of the upper 
pit exhibited a pipe filled with the sand. At first this pipe was 
almost vertical, then it narrowed and took a nearly horizontal 
course, after which it descended more steeply till it died out at 
a vertical depth of about 25 feet from the top of the Chalk. The 
walls of a trench cut into the isthmus disclosed a section of @ 
roughly horizontal fissure in the Chalk, measuring about 43 or 
5) feet 4rom top to bottom, and filled with sand; in this were 
horizontal streaks of Chalk (probably reconstituted), the largest 
being 5 or 6 feet long, but only a few inches thick. The Chalk 
above was quite unbroken, and in the thinnest part not much less 
‘than 3 feet thick. The southern wall of the isthmus disclosed a 
sand-pipe, which possibly might have been connected with this 
fissure. In this part of the wall the flint-layers are locally bent 
into a sharp arch, the crown of which is cut through by the pipe. 
This evidently was rather large in size and irregular in shape, 
being apparently filled with the glacial sand.’ 

The quarry shows two other pipes, one of which, irregular in 
form and almost horizontal in direction, is filled with sand con- 
taining unworn flints and lumps of chalk. Its course seems to have 
been modified by the bands of flints. 


Proceeding now to sections which are more closely comparable 
with those of Moen, we select (1) a very large chalk-pit, at the 


southern corner of a wood and rather more than 3 mile west 


of the town railway-station, which cuts deep into the hill-slope on 
the western side of the opening. The Chalk, towards the upper 
end, almost reaches the surface. As the wall of the pit curves 


* In one place a surface of Chalk had recently been laid bare, more than a 
rood in extent, from which about 5 feet of material, mostly clayey, had been 
removed ; on it lay numerous boulders, showing that they had been fairly 
common either in or at the bottom of the Drift. We estimated roughly a 
cubic foot of boulder-rock to a cubic yard of clay. 

2 Pits are noticed by C. Struckmann, Zeitschr. d. Deutsch. Geol. Gesellsch. 
vol. xxxi (1879) p. 788, and F. Wahnschaffe, ¢bid. vol. xxxiv (1882) p. 593. 
The former makes seven divisions in the Drift, the latter three (besides that 
which we take for the surface-material), namely, clay, sand, clay. Both 
authors mention the occurrence of 2 species of freshwater shells about the 
middle of the sand, and of marine (Tel/lina solidula, one specimen with both 
valves) towards the top, but Wahnschaffe asserts that these occur only locally 
in lenticular layers. ‘They refer especially to ‘ Kister’s Pit,’ which we believe 
to be one farther east, now disused and not showing any clear sections. 

3 To represent the section in a diagram is extremely difficult, because the 
pipe had been left by the workmen so as to form, with some of the adjacent. 
Chalk, a kind of buttress, descending in a series of steps. As the pit has been 
opened to get chalk for whitening, the sand has been avoided as useless. 


Vol. 55.] CHALK AND DRIFT IN MOEN AND RUGEN. 315 


round towards the north, clay (seemingly) makes its appearance, 
thickening to perhaps 30 feet rather west of the highest point 
(at which the Drift must measure about 12 feet); but this part 
was so thickly powdered with chalk-dust that all details were 
concealed. The section, however, became quite clear on the eastern 
side, and lower down the hill can be readily examined. Here 
the surface of the Chalk has a steeper slope than is shown in the 
diagram (fig. 3), for it is plunging slightly beneath the Drift, and thus 


Fig. 3.—Section in pit, half-a-mile west of Krampass- 
Sassnitz railway-station (Rigen). 


1 = Chalk. 3 = Sand. 
2a = Lower Clay. 4 — Drift, washed over. 
26 = Upper Clay. 5 = Drift-material (apparently 


a filled-up pit). 


(The seemingly abrupt termination of the Drift is due to a projection 
of the wall of Chalk hiding the other from view.) 


the angle may amount to as much as 40°. Directly upon this surface,. 
without any intervening layer of unworn flints, rested a bed of clay. 
This, at the lower end, where we examined it, was about 4 feet 
thick. It became rather more at a higher level, but then it passed. 
up into a layer, 8 or 10 inches thick, of gravel in a clayey matrix. 
The pebbles were fairly rounded, often about as big as a horse- 
bean, but sometimes larger, up to the size of a pigeon’s egg.. 
Above this layer came about 5 feet of well-stratified, occasionally 
false-bedded sand, resembling that already described, in which now 
and then was a seam of grit, including one or two small pebbles. 
This was covered by a second bed of clay. Both are stony, the 
upper perhaps slightly the more so; the lower is here a little more 
sandy. In the coast-sections it is generally the upper clay that is 
slightly more sandy. The diagram (fig. 5) shows—and this is made 
still clearer by a study of the pit as a whole—that the flexures of 
the Chalk must be anterior to the surface-contours of that rock ; 
or, in other words, that the present dip of the Glacial deposits was 


316 PROF. T. @, BONNEY AND REV. E. HILL ON THE [Aug. 1899, 


not determined by post-Glacial earth-movements.’ It also shows a 
tripartite division of the Drift, inexplicable by folding and uncon- 
nected with faulting. 


a 
3 
: 2 
rs 3 
a aie 
~~ 
oS sa 
[<P] a 
aS) A 
<S Set 
3 iS) 
- 2 
242 
c Gy Tey ts 
= mH 
© P ff, i Seat 
yf 
= oy eB co HH 19 
: ~ 
La) a \ 
< Ah Ht 
S 
~~! 
AY) 
S 
S 
re 
~~ 
8 z 
= = 
22 =] 
> (o} 
& 2 
S 
fi 8 
| 2 
ah a 
or 
ie 
— 
oO © 
“4 5 8 
“s & Be 
1 Giug 
OW HY 
ame | as | 
ms = 30 
aan 


(2)"}We pass from this rather elevated section to one where the 
tripartite Drift is almost at sea-level. The well-known section 


Similar evidence is afforded by sections such as that near the Blockhouse 
(p. 320) and that south of the Lenzerbach. The not unfrequent general 
concordance between the base of the Drift and the flint-bands in the Chalk 
may be due to the influence of the,hard material in determining the surface of 


wv 


the latter rock. 


Vol. 55.] CHALK AND DRIFT IN MOEN AND RUGEN. 317 


at the Kielerbach has been so often described * that a brief notice 
may suffice. Here the Drift, which at first sight appears to be 
interstratified with the Chalk, dips at an angle of 30° (approxi- 
mately). The lower clay (identical with that seen in the same 
position at several other places on the coast) is dull grey, and 
contains pebbles of various rocks (including a dark limestone, but, 
so far as we saw, no chalk) as well as a few small boulders of 
crystalline rock from 12 to 18 inches in diameter. The exact 
thickness of this clay is not easily ascertained, but it is certainly 
not less than 18 feet (fig. 4, p. 316). Above it, with a sharp line of 
division, is sand (at the bottom of which we sometimes find a well- 
marked layer of stones)? about 15 feet thick. This sand is clearly 
but rather irregularly stratified, being occasionally false-bedded and 
in places slightly clayey. Above this comes another clay, con- 
taining some stones, but rather more sandy than the lower one. 
Its thickness in the section more particularly studied was about 
4 feet ; but this evidently was only a fragment. Chalk rises up in 
the cliff north of the section and seems to overlie the Drift on the 
south (fig. 5). On the former side the surface of the Chalk is 


Fig. 5.—Section at the Kielerbach (viewed from a position | 
south of that taken in fig. 4). , 


oy 


a 


Lg 


stones at base). 
4= Soil. 
5 = Talus of Drift-material, 


2a = Lower Clay. 
26 = Upper Clay. 


1 = Chalk. | 3 = False-bedded band (layer of 


certainly uneven, becoming rather steeper in the neighbourhood of 
the beach, and on the latter side it is represented as irregular 
by earlier observers. 

Another section, about + mile to the south, shows the same set 
of beds seemingly intercalated in the Chalk and dipping at about the 


1 As, for example, by J. Geikie, ‘Great Ice Age,’ 3rd ed. (1894) ch. xxix. 
One of them was a foot in diameter. 


Figs, 6 & 7.—Sections near the Waldhalle (Rigen), from 
the south and north. 


1 = Chalk. 3 a= Wash-over of clay, some sand 
2 = Clay. visible 7m situ. 


2'= Rather sandy clay, probably be- eyis oes me be ii ma 


longing to the upper division. parallel to the visible junction. 
2"=Lower part of the whitish x=Rib of Chalk, similarly 
Boulder Clay. marked in fig. 7. 


7a ng 
My aOR a 
rm, (- Bh ae Ricken 
ie es Engrs 


sen 
aces Weg cgi ttt 


1 = Ohalk. 16: all this part and below is 
Chalk washed over. 
la = Chalk (apparently). 2 = Lower Clay. 


3 = Sand, 


ERRATUM, p. 318, Fres. 6 & 7. 


[Owing to a mistake in selecting the drawings for reproduction, a pair 
(Figs. 6 & 7) representing a section south of the KotiickErBacu have been 
used to illustrate corresponding views under tie Waldhalle. The asso- 
ciation of Chalk and Drift is nearly the same in both, but the true 
Waldhalle sections do not show the Boulder Clay coming in again on the 
edge of the Chalk-cliff as it descends to the beach.—T. G. B., July 17th, 
1899. ] 


Vol. 55.] CHALK AND DRIFT IN MOEN AND RUGEN. 319 


same angle southward, beyond which is a third section exhibiting 
similar relations.’ 

(3) At the Wissowerbach is found a similar apparent inter- 
calation of the tripartite Drift; but here the uppermost clay is 
thicker and contains pockets of sand. In fact, these three deposits 
occur in several places; and, in some, a line of scattered boulders 
may be seen in the bottom clay just above the Chalk. One of the 
largest of them was about 5 feet in diameter, and the surface of 
the Chalk beneath seemed to be slightly depressed—probably a 
result of solution under pressure. 

We may conclude, then, from these three groups of sections that 
a tripartite division exists in the Drift, wiatever explanation we 
may offer of its relations to the Chalk. 


(4) The next section introduces a peculiar Boulder Clay, which 
we saw well exhibited in the neighbourhood of the Waldhalle Re- 
staurant. To the south, at or near Wissowerklinken, this clay rests 
on Chalk with sloping bands of flint. It is whitish, full of more or 
less angular flints, but it also contains some boulders of crystalline 
rock. From it two bold aiguilles have been sculptured. The 
accompanying section (fig. 6) was drawn from the edge of the cliff 
east of the restaurant, near a third and smaller aiguille of the 
same clay, and shows that deposit overlying the ordinary Drift. 
‘This diagram and the next (fig. 7) represent the southern and 
northern faces of the same rock-buttress, and indicate that the 
Chalk rises, apparently abruptly, on the seaward side of the ordi- 
nary Drift. The basal line of the boulders in the (presumably) 
lower clay here seems to be vertical,” but we think that both 
the Drift and the surface of the Chalk more probably dip inland 
at a moderate angle. We were convinced by our examination 
of the cliffs that near here they exhibit a difference of at least 
50 feet in the level of the surface of the Chalk, and give a section of 
a gully descending northward to the sea: the whitish Boulder Clay 
extending almost horizontally over both the Chalk and the Drift of 
ordinary type. 

(5) The next section, from the part called Fahrnitzer Ufer, 
exhibits a considerable mass of Drift, from 40 to 50 feet in vertical 
height, backed or flanked by Chalk, which forms the left-hand 
portion of the cliff. Against the latter a Boulder Clay rests 


1 See Johnstrup, Zeitschr. d. Deutsch. Geol. Gesellsch. vol. xxvi (1874) p. 533, 
and D. G. Berendt, 27d. vol. xli (1889) p. 148. These sections afford an excellent 
example of the diversity of interpretation of the same evidence. Berendt sees 
clear evidence of folding, especially in the southernmost section, without, how- 
ever, accounting for the extraordinarily irregular form of the upper arm of clay 
(see his diagram). H. Credner (op. cit. p. 366) observes that Berendt’s fold is 
founded ‘auf einer argen Tauschung,’ and says that the relations of the Chalk 
and Drift at the Kielerbach are due to faults, three in number. Berendt 
retorts, op. cit. vol. xlii (1890) p. 583, that Credner’s faults have no sounder 
basis, for he had been to the spot and had hunted for them in vain. 

2 The section is inaccessible, and the sketches were made from above, so that 
the apparent slope may be anything but the true one. 


320 PROF. T. @ BONNEY AND REV. E. HILL ON THE [Aug. 1899, 


(probably the lower), the junction in one place being vertical. The 
Drift apparently consists of the usual three members, but all are 
much contorted, and in the upper clay are seen two large boulders: 
or prominences of Chalk. So the section appears from above; it 
is visible, though not so well, from below, but it could only be 
examined by a bird, for the crest of the cliff must be fully 120 feet 
above the beach. 

These two localities show the Drifts apparently lying at very 
high angles, and they are not the only instances. 

(6) Between the Lenzerbach and Sassnitz, in the cliffs under the 
Blockhouse at the corner of the forest, and some yards above the 
shore, is found the usual grey lower Boulder Clay, with the line of 
boulders at the bottom; it rests upon Chalk, with bands of nodular 


Fig. 8.—Section under the Blockhouse (Rigen). 


1 = Chalk. 26 = Upper Clay. 5 = Slip of Drift. 
2a = Lower Clay, with 3 = Bedded sand. 5'= Wash-over. R 
line of boulders 4 = Sand, ete. 6 = Recess, showing 
at the base. clay at back. 


flint, which dip on the whole at a rather higher angle than the 
section of the (slightly irregular) surface of junction. Over this clay 
comes the usual stratified sand, capped by the upper (more sandy) 
clay, which passes up into a rather confusedly mixed clay and sand, 
containing one or two boulders and probably representing the Ober- 
diluvium. ‘The base of the Drift, as shown in the diagram 
(fig. 8), first slopes downward at an angle of 25° to 30°, and then, 
on coming within 3 or 4 yards of the beach, descends almost verti- 
cally. In the lower part of the section the grey Boulder Clay is 
seen to rest against an upright face of Chalk and to cut across the 


Vol.5 5. | CHALK AND DRIFT IN MOEN AND RUGEN. 321 


sloping lines of flint... After about 10 yards, masked by slip, the 
Boulder Clay is exposed for some little distance in craglets by the 
beach. 


These proups of sections may, we hope, suffice as types of those 
examined during our stay at Sassnitz. We have only to add that 
the lower Boulder Clay, though sometimes it differed but slightly 
from the upper, did so sufficiently to show that a repetition in con- 
sequence of folding was not possible. Pebbles are fairly common 
in both clays, but less so than in the average Boulder Clay of 
Eastern England. They are generally more or less well rounded, 
and consist mainly of crystalline rock, with some grits or quartzites, 
hard dark argillites, and limestones. Flints are not frequent, and 
chalkisrare. Both clays, but more particularly the lower one, beara 
general resemblance to the Cromer Till, especially to its representative 
near Lowestoft, and to the lowest Boulder Clay near Bridlington, 
allowing for the frequent absence of chalk-pebbles. The lower 
clay is of a rather deeper grey than the upper, and in drying it 
becomes more definitely jointed, breaking into rude prisms; larger 
boulders are somewhat commoner in it, and they frequently form a 
layer almost at the base. Still, they are also present in the upper 
clay, and no doubt in the Oberdiluvium as well, for they are often 
dotted over the surface of the ground in the forest. 


TV. Concivusions. 


What is the explanation of this singular cellocation of Chalk 
and Glacial Drift? It must be the same in the case of both Moen 
and Riigen, for the sections in the two islands, though not identical, 
differ only in detail. We must remark at the outset that to liken 
them to the sections in the cliffs near Cromer is, in our opinion, mis- 
leading and erroneous.” In the former the Glacial Drift is a local 
incident in the Chalk; in the latter the Chalk is similarly related 
to the Drift. In Norfolk, so far as we can tell, the Chalks never 
in situ®; in the two Baltic islands it is almost invariably so. 

Some of the sections in these islands would be most simply ex- 
plained by claiming the Glacial Drift as an episode of the age of 
Belemnitella mucronata. But this hypothesis, we imagine, would 
find few defenders and does not need serious discussion. 


The next hypothesis, which at the present time numbers many 
supporters, asserts the strange intercalation of the Drift and Chalk 


1 This relation could not be mistaken, for some of the clay had fallen out- 
werds and formed a recess in the cliff, with the Chalk fora wall, about the 
height of a man, on the right (or more northerly) side. 

2 Phenomena resembling those of the Lower Till of the Cromer district, so 
far as we can ascertain from the literature, of the subject, may occur on the 
North German mainland. Perhaps also they may be found at Arkona, the 
northernmost extremity of Rigen, but this we had not time to visit. 

3 We refer, of course, to the Chalk-masses in the Drift. The former rock is 
in situ below it, as can be often seen, but only rises a very little distance above 
the shore. : 


Q.J.G.8. No. 219. Y 


322 PROF, T. G. BONNEY AND REV. B. HILL ON THE [Aug. 1899, 


to be due to the action of an ice-sheet which had crept from 
Scandinavia across the present bed of the Baltic. Two explanations 
may be offered of its precise method of working :—One, that the 
pressure of the immense body of ice tore off huge masses from the 
Chalk, which for a time had opposed its progress, and carried them 
onwards (though not necessarily for any great distance) in such 
wise that they became mixed up with the materials of its terminal 
or subglacial moraine; the other, that the Chalk is im situ, but that 
the Drift has been either forced into glens and depressions in it, or 
banked up against pre-existing cliffs. Of these alternatives we 
regard the latter as the less improbable, because, ay already stated, 
the Chalk, in both Moen and Rigen, for hundreds of yards is as 
clearly in situ as it is between Freshwater Gate and the Needles in 
the Isle of Wight. But we must remember that in these islands 
the present coast-line cannot be identical with that which existed 
in the Ice Age. The Drift is constantly slipping down, much as it 
does at Cromer and in Holderness, and before long is swept away 
by the waves." As the Chalk-cliffs rise steeply, commonly have 
no talus at their base, and do not project as headlands, we infer 
that this rock recedes almost as fast as the Drift. Hence the 
contour-line corresponding to the present Ordnance datum must 
have been, in Glacial times, not less than some few hundred yards 
away on the seaward side. If so, the tripartite arrangement of the 
rift, often so orderly, becomes more than ever difficult to explain 
on the hypothesis that the material was transported or thrust up 
from the lowland now covered by the Baltic. . Again, as boulders 
are scattered over the plateau, often at heights of at least 300 feet 
above sea-level, the ice must either have overridden the sand? 
(Oberdiluvium) and dropped them on it, or have deposited them 
in that or the upper Boulder Clay, which has been subsequently 
washed away, and must have done this, in either case, without dis- 
turbing the generally even bedding in one or other of the sands. Only 
twice, at most, as already mentioned, did we see anything in Rigen 
resembling the Contorted Drift of Cromer, and certainly nothing in 
the cliffs of Moen. The steep angles at which these bedded Drifts 
lie are sometimes very puzzling, but the absence of anything like 
contortions was no less singular. In short, though both forms of 
the ice-thrust hypothesis were kept constantly in view, we could 
find nothing in either island which was favourable to it, and very 
much which was hostile. 


A third hypothesis accounts for the association of Drift and Chalk 
by folding or faulting,® or by both. Obviously such disturbances 


‘ The proofs of slipping were very conspicuous in both islands at the time of 
our visit. 

2 According to the Geological Map of Rigen the sand of the forest (p. 312), 
with probably the whitish Boulder Clay near the Waldhalle, belongs to the 
‘Upper Diluvium,’ and the tripartite Drift to the ‘ Lower Diluvium ’: the former 
of which seems to be more widespread than, and generally unconformable 
with, the other. ; 

3 Faulting was the explanation advocated by Puggaard and adopted by 
Lyell. 


Vol. 55.] CHALK AND DRIFT IN MOEN AND RUGEN. 325 


may have occurred; but as post-Glacial movements on a large scale 
are not generally admitted by geologists, very clear evidence may 
reasonably be demanded. That we were unable tu find. The Chalk 
obviously has been greatly folded, but this, as we have shown above, 
took place before the Glacial Period; faults also may occasionally 
be detected, but these as a rule are not conspicuous and seemingly 
not large, being more of the nature of fractures and slips due to that 
folding. We sometimes had the opportunity of examining from the 
beach a continuous wall of Chalk beneath one of the apparently 
infolded or infaulted masses of Drift, and we were unable to detect 
in it the slightest sign of rupture or displacement. The flexures 
shown by the bands of nodular flints are sometimes as steep and 
even more remarkable than those exhibited in the cliffs near the 
Needles ; but they were formed, so far as we could discover, long 
enough before the Great Ice Age to allow time for the region 
to be sculptured into something like its present contours. We 
therefore think that the evidence which we have cited, both for 
Moen and for Riigen, cannot be reconciled with Puggaard’s hypo- 
thesis, and we have been compelled, though at first a little prejudiced 
in its favour, to reject it, no less than that of folding, as irrecon- 
cilable with the facts. 


But, as we are unable to accept any of the hypotheses which at 
present apparently occupy the field, we may be asked to show that 
some other one is possible. It must explain the following facts :— 


(1) The tripartite’ and generally orderly arrangement of the 
Drift. 

(2) The rather frequent and sometimes marked unconformity 
between the Drift and the Chalk. 

(3) The occurrence, not seldom, of the former in either valleys 
or clefts of the latter. 

(4) The great variation in the angle at which these beds of 
clay and sand are inclined (from almost horizontal to 
almost vertical) without losing their general evenness of 
bedding.” 

Let us suppose, then, that by the beginning of the Glacial epoch 
the surface of Moen and Rugen had assumed nearly its present 
outlines. As the temperature falls, snow begins to clothe the 
slopes ; as the cold increases, it becomes permanent. On the hill- 
tops the snow will be comparatively thin, but it thickens on their 
slopes and accumulates in the valleys until these are nearly or quite 
filled. Glaciers, however, owing to the smallness of the gathering- 
ground, probably will not be formed.’ The lines of downs in each 
island become hardly more than undulating plateaux of snow. 


1 At any rate, in Riigen ; throughout we are referring only to the Drift 
(Lower Diluvium) intercalated with the Chalk. 

2 This suggests that, whatever be the explanation, the beds, when moved, were 
probably more coherent than they are now, or, in other words, were frozen 
solid. 

3 As we can see at the edge of regions covered with almost continental ice at 
the present day, small insular tracts merely have a covering of frozen snow. 

Ys 


324 PROF. T. G. BONNEY AND REV. E. HILL ON THE [Aug. 1899, 


Suppose, afte r this, the deposit of Drift to begin (in what way we 
do not now enquire, merely assuming the covering of frozen snow or 
ice to remain undisturbed); upon this covering is laid, first a clay, 
next a-stratified sand, then another clay." This completed, suppose 
the climate to become gradually milder: Any bare snow will be 
melted ; it will be followed, but more closely, by that far larger 
quantity buried beneath the Drift,’ and the Drift itself, if frozen, 
will be probably the last to yield. The latter, as the snow melted, 
would gradually settle down. Where the ground beneath was flat, 
it would be more or less horizontal; where it was above a buried 
hill-slope, it would finally come to rest at the same angle. 

But, where the snow has masked glens or craglets,’ the beds of 
the Drift might be gradually twisted, as it descended, from a nearly 
horizontal position to one almost vertical, and its base, as that 
became softened, would mould itself on the new surface. If 
snow or frozen water had filled up the fissures, the Drift would 
gradually make its way into these as sand works down an ordinary 
pipe, though, as a rule, more rapidly. 

It might be suggested that these fissures and the inequalities in 
the surface of the Chalk were formed by subterranean denudation, 
as is so common in England. ‘This is a very natural explanation, 
and it may have sometimes happened, but we think not often—at 
any rate as the dominant factor—because flint (especially unworn) is 
so scarce at the junction of the Chalk and the Drift. The latter 
sometimes has been affected by movements analogous to faults, but 
not the Chalk, and what has happened has only been slight local 
disturbance, not faulting in the ordinary sense of the term. 


This hypothesis obviously is not recommended by its simplicity. 
Nevertheless, in our opinion, it agrees with all the facts which we 
observed, and we cannot say that of the others. They at any rate 
appear to be untenable, whether the one now proposed be 
correct or not. We may be asked to state the circumstances under 
which the Drift was deposited, but, as we have intimated, this 
question is quite separate from that which has been discussed in 
the foregoing pages; hence we have deliberately refrained from 
entering upon a topic still more highly controversial. 


Discussion. 


Mr. LampriucH said that he feared that it would be difficult to 
deal adequately with this interesting paper, if the Authors wished 


1 In some places the series may be less complete. 

* How long frozen snow can be preserved is indicated by the well-known case 
of ice under lava described by Lyell (‘ Principles, 11th ed. 1872, vol. ii, p. 38). 
For this point and the slow thawing of the Drift, we may cite the existence 
at the present day of permanently-frozen ground beneath the subsoil in the 
Arctic regions. 

° The Chalk in both is!ands, as may be seen from exposed surfaces, has a 
rather unusual tendency to be furrowed and grooved: channels more or less 
semicircular in section, sometimes deeper than broad, forming on the face of 
the cliffs and especially on their upper part. 


Wolts5.1 CHALK AND DRIFI IN MOEN AND RUGEN. 3295 


to abstain from discussing the origin of the Drifts in the area. He 
complimented them upon their ingenious explanation of the pheno- 
mena described, but thought that a simpler one might have been 
adopted. He called attention to the huge transported masses of 
Secondary rocks included in the Drift at various points along the 
British margin of the North Sea, from Aberdeenshire to Norfolk, 
which prove that, whatever might be the nature of the glacial 
agency, it was capable of disturbing and detaching portions of the 
solid strata; and he thought that the sections which illustrated 
the paper demonstrated the first stages of this process. He asked 
the Authors whether they could give any information regarding the 
shells which had been said to occur in these Drifts. 

Mr. A. E. Satter asked whether it was not possible to regard 
these deposits as fluyiatile accumulations, derived from old and 
extensive drainage-areas, now greatly curtailed and altered by 
marine and subaerial agencies. ‘The occurrence of a cold period 
in former times, and the presence of these curious Drifts on a rock 
soluble in water, might have brought about the complicated phe- 
nomena observed. 

Prof. Srerzey said that, although these interesting sections are 
not exactly paralleled in this country, it 1s not improbable that 
they are only intenser manifestations of the familiar relations of 
the Chalk of Britain to the Drift. When the Midland Railway was 
made from Luton northward, a bed of black clay was exposed 
about 1 foot thick, apparently interstratified in the upper part of 
the section, which might perhaps have been introduced from the 
surface. The examples of beds of sand in the Chalk which were 
introduced by means of pipes were more common. In the south of 
Essex, not far from the Boulder Clay, a railway-section some ten 
years since showed the Chalk bent into several undulations or corru- 
gations in which the ancient gravels above it participated, and 
where the Chalk ended to the south, other gravel-beds and clays 
were highly inclined. The faults in the Thames Valley Chalk, 
although on a small scale, were so numerous that they suggesied 
the intercalation of the Drift with the Chalk when denudation has 
not removed the whole of the Drift from faulted surfaces. No one 
explanation need be relied upon when the circumstances indicated 
local alternatives. 

Mr. R. M. Brypone observed that the gradual sinking of a level 
bed of Drift into a ravine would result in the lowest bed of the 
Drift coating both sides of the ravine, instead of bringing the top- 
most bea of the Drift in close contact with one side of the ravine, as 
shown in some of the diagrams. 

Mr. Srrauan was relieved to find that be was not called upon to 
believe in wholesale post-Glacial folding of strata. The Authors had 
stated that no comparison was possible between the cliffs of these 
Baltic islands and those of Cromer, but their diagrams strongly 
reminded him of what he had seen of the Chalk-masses and 
undercutting Drifts in the Norfolk cliffs. He asked for further 
explanation of the difference insisted on by the Authors. 


326 THE CHALK AND DRIFT IN MOEN AND RUGEN. [ Aug. 1899, 


Prof. Jupp congratulated the Authors on having so courageously 
taken up the study of sections which had given rise to very great 
divergences of opinion among geologists. The caution of the 
Authors in speculating upon causes was not Jess admirable than 
their boldness in attacking this difficult problem. Lyell had 
evidently felt hesitation in referring to these sections, after his 
original description of them in 1834, till his sections were confirmed 
by the detailed drawings of Puggaard. Possibly some of the phe- 
nomena exhibited might be due to irregular subterranean solution 
of the Chalk. It was pointed out that vast masses of Tertiary 
strata, from Eocene to Crag, are ‘ piped down’ into the Chalk over 
vast areas in the North Downs, and if that district were cut open in 
sea-cliffs, complexities would probably be exposed rivalling those of 
Moen and Rugen. 

The Prestpent and Prof. Warts also spoke. 

The Rev. Epwriy Hitt, in repiying, said he wished that former 
writers could have been all present: discussion would have been 
warm, for each repudiated his predecessors’ views. They all had 
supposed the phenomena due to the causes which had disturbed the 
Chalk: however, those causes had folded the Chalk, and the Drifts 
were not folded. As to ice-transport, it would be like transporting 
the Flamborough peninsula: the areas each showed several miles otf 
continuous Chalk-cliff. Likeness to Cromer there was none. Where 
a ravine was steep on one side, the Drift would sink on to the other 
side. If the question about ‘ peneplain ’ meant, Had the areas at one 
time been above sea-level? no doubt they had, and had been much 
furrowed. As to melting from below, earth-heat naturally pro- 
duced that. Subterranean erosion was a very natural view, but the 
evidence seemed unfavourable to it. 

Prof. Bonnny said that he would only add a few words to 
Mr. Hill’s answer. He must repeat emphatically that in Moen and 
Riigen the Drift was a mere local incident in the Chalk (which was 
clearly in sitw), while at Cromer the opposite was the case. It was 
impossible to compare the two districts. If subterranean erosion 
had occurred, where were the loose flints ? The term ‘ peneplain’ had 
been mentioned. For himself he had vague ideas as to what that 
mongrel word meant, and he thought that its indefiniteness added 
to its charm for some minds; but if the Isle of Wight from near 
Yarmouth to High Down was a peneplain, so were Moen and 
Rigen: if not, they were not. He had read of shells (3 species 
marine, and some freshwater at another spot) being found in the 
Riigen Drift. They were extremely local, and he had seen none. He 
could quite understand that some of the speakers would have been 
glad if the subject had been further complicated by the expression 
of any opinion which the Authors might have formed as to the mode 
in which the Drift had been deposited; but that desire would have 
to go ungratified. He pointed out that Mr. Lamplugh, by ascribing 
the contortion in the Chalk at the railway-station pit in Riigen to the 
thrust of land-ice, as in one or two other cases in his remarks, was 
quietly begging a fundamental question. 


Vol. 55.] LIMESTONE-KNOLLS IN THE CRAVEN DISTRICT. 327 


21. On Limestonn-xNotis in the Craven Disrrict of YORKSHIRE 
and BLSEWHERE. By J. E. Marr, Esq., M.A., F.R.S., F.G.S. 
(Read April 26th, 1899.) 


[Prarn XXIV.] 


CoNTENTS. 
Page 
PAu TO CECULO Ta PM cian oo 5 a iene oad 2 eaaiticees oa SCRE seat o 
Ul, General Structure of the: District ..........cis<s+e0<o0-cuene 322 


IIL. Nature of the Disturbances south of the Craven Faults. 331 
IV. Description of the Knolls near Cracoe and Settle, and 


MNO feSH Ome Nite I=SHIECEIINO” S.csccssdec<ocdaeeoecepmecceeees 338 
Weenie Abs CeCe baum eee ee oaks b vickeic ov cid kia w sun conte este ee ee 343 
VI. Comparison of the Deposits on both sides of the 
AA ear ies Pe Te eS lara ina cals och sinw, abe aiahoROR EEE 349 
VII. Natuie of the Movements which have affected the 
Roreks: south of the Craven Faults ........<s00ceccentecuse 351 
VIIL. Knolls of Limestone in other Areas ............... .seesees 354 
Me) Comcluidimns) ReMmiaGks 25. 2005 <s<0ecsqedenecasessa¥etdeeeenerade 307 


I. IntRopuctTIon. 


Ir is now many years since I began to pay attention to the frequent 
and often sudden expansion of masses of limestone associated with 
other deposits, and in the year 1888 I had the good fortune to 
examine some of the remarkable limestone-masses of the Craven 
district under the personal guidance of Mr. R. H. Tiddeman, to 
whom we owe our knowledge of the structure of these masses. 
Mr. Tiddeman has described and offered an explanation of these 
structures in a series of papers, which, though brief, are remarkable 
for their pithiness and lucidity, and reference to them will at 
once enable anyone to understand the structure of the irregular 
limestone-masses and the associated phenomena. 

Mr. Tiddeman’s earliest account of these structures appears in 
Rep. Brit. Assoc. 1889 (Newcastle-on-Tyne) p. 600, and further 
descriptions by him will be found in the Excursion-guide for the 
Leeds Meeting of the British Association in 1890 and that for the 
London Meeting of the Geological Congress. A brief summary of 
Mr. Tiddeman’s views is published in an account of an excursion 
to the Winterburn Valley,” and the substance of his presidential 
address to a Yorkshire scientific society, which largely deals with 
the limestone-masses, appeared in the ‘Craven Herald’ for Jan. 
29th, 1892. I shall endeavour to give a summary of Mr. Tiddeman’s _ 
work as published in these various papers, and shall refer to his 
explanation of the origin of the irregular masses of limestone ard 
the accompanying breccias. 


‘ Congrés Géol. Internat. Compte-rendu, 4@me Sess, 1888 [publ. 1891] 
pp. 319-323 & 324-329. 
2 Trans. Leeds Geol. Assoc. pt. vi (1891) p. 111. 


328 MR. J. E. MARR ON LIMESTONE-KNOLIS IN [ Aug. 1899, 


It is with regret that I have been driven to adopt another ex- 
planation for these phenomena, but my regret is mitigated by the 
fact that the explanation is a matter of opinion, which will stand or 
fall, as the result of future work, while the actual structure of the 
area which has been unravelled by Mr. Tiddeman single-handed is of 
prime importance, and he has described phenomena which, whatever 
be the explanation offered to account for them, are undoubtedly 
of extreme interest. 


Il. Generar StrRuctTURE oF THE Disrricr. 


Under this heading I propose to give a brief account of 
Mr. Tiddeman’s work, extracted from the papers to which I have 
already alluded, in order to render my own communication more 
intelligible to the reader. In doing so it will be unnecessary to 
specify the work done previous to Mr. Tiddeman’s elucidation of the 
phenomena which it is the main purpose of this paper to describe, 
for everyone interested in the geology of the North of England is 
aware of the existence and general nature of the Craven Faults, 
and is acquainted with the principal geological features of the country 
north and south of those faults. 

There are three main branches of the Craven Fault, the northern- 
most of which runs from Ingleton at least as far as Pateley Bridge ; 
the middle branch runs through Ingleton, a short distance south 
of the first, to Gordale; while the southernmost leaves the middle 
branch near Settle, and runs to Skipton.! The Carboniferous rocks 
on the north of the fault-system differ as a whole from those lying 
on the south in their present characters and thickness, and in the 
amount of disturbance that they have undergone. Therocks on the 
north side of the faults exhibit little evidence of disturbance, while 
those on the south side are thrown into a series of anticlinal and 
synclinal folds, of which the axes run in a general east-north-easterly 
and west-south-westerly direction.” The difference in the characters 
of the rocks of the two areas is very marked. The following 
classification is tabulated by Mr. Tiddeman * :— 


Thickness in Thickness in 
SoutHern Tyr. Jeet. Nortuern Type. Jeet. 

Coal Measures (Ingleton). 1500 Coal Measures ...] Incomplete near 
Mullstone Grits’ .......0...- 3900 Millstone Grits ... } the faults, 
Bowland Shales ............ 300 to 1000 
Pendleside Grits (incon- | Yoredale Series ... 400 to 900 

<1 01 Se ere or 0 to 250 
Pendleside Limestone ... 0 to 400 
Shales-with-limestones ... 2500 Carboniferous 
Clitheroe Limestone ...... +3250 (no Limestone ...... 400 to 800 

base). 


' Tiddeman, Rep. Brit. Assoc. 1889 (N’castle-on-Tyne) p. 600. 

? Tiddeman, Congrés Géol. Internat. Compte-rendu, 4@me Sess. 1888 [1891] 
p. 319. 

> Rep. Brit. Assoc. 1889 (N’castle-on-Tyne) p. 601 & Congres Géol. Internat. 
Compte-rendu, 4eme Sess. 1888 [1891] p. 314. 


Wol.i5 5.4] THE CRAVEN DISTRICT OF YORKSHIRE. 329 


It will be observed that the estimated thickness of the Lower 
Carboniferous rocks on the south side of the fault-system is much 
greater than that on the north side. 

The irregular masses of limestone which Mr. Tiddeman has called 
reef-kuolls, to which I shall allude in the following pages as 
knolls, are found on the south of the fault-system, and he speaks 
thus of their occurrence in the Pendleside and Clitheroe Lime- 
stones :—‘The form and the system of arrangement of the white 
limestones [of the knolls] are peculiar. The stratification of the 
deposits is usually somewhat obscure, and the masses rise in the 
form of conical or ovoid eminences up to a height of 300 or 400 feet. 
The change of thickness occurs in a very limited horizontal extent. 
These eminences ordinarily present upon their sides strata which 
dip away from the mass in all directions; but when the rocks of 
the eminences have been quarried, or denuded by atmospheric 
agents, one sees that the stratification, rough as it is, preserves its 
horizontality or agrees with the direction of inclination of the sur- 
rounding country...... The knolls are seen at Malham in the 
valley of the Aire, at Winterburn Reservoir, Swinden, and other 
localities in the neighbourhood of Grassington, in the valley of the 
Wharfe, where they are found in profusion. They have never been 
discovered north of the Craven Faults. In the localities which have 
been mentioned they are all developments of the Pendleside Lime- 
stone. In the neighbourhood of Clitheroe, on the other hand, these 
knolls are all excrescences of the Clitheroe Limestone. In the case 
of the Pendleside Limestone, they penetrate the Bowland Shales 
which surmount them; around Clitheroe they bury themselves in 
the Shales-with-limestones.’ * 

Associated with the knolls are breccias, described as follows :— 
‘At the foot of these mounds, or reef-knolls as I would call them, 
we have in many places a breccia formed of fragments of the 
limestone, which, I take it, have been broken off the reef above 
between wind and water, and have subsequently been covered up 
by the mud of the Bowland Shales and compacted into a breccia. 
Fragments of limestone similarly consolidated occur, though more 
rarely, on the sides of these knolls themselves. I would call these 
reef-breccias.’* The shales of the breccias at Winterburn ‘ were 
seen curving round to the shape of the boulders, showing their 
deposition while the shales were still in a soft plastic form.’ * 

It will be seen that the main points of interest are (1) the fault- 
system ; (11) the differences in thickness and characters of the rocks 
north and south of the fault; (i) the knolls; and (iv) the accom- 
panying breccias; and of these our knowledge of the latter two is 
entirely dueto Mr. Tiddeman. I now proceed to give a brief outline 
of his explanation of the phenomena. 


1 The passage above quoted is translated from the Report of the Internat. 
Geol. Congress, 4th Sess. 1888 [1891] p. 321, with a few verbal alterations, 
which do not affect its meaning. 

* Tiddeman, Rep. Brit. Assoc. 1889 (N*castle-on- Tyne) p. 602. 

8 Trans. Leeds Geol. Assoc. pt. vi (1891) p. 112. 


330 MR. J. E. MARR ON LIMESTONE-KNOLLS IN [ Aug. 1899, 


He supposes that disturbance was going on all through the period 
of deposition of the Lower Carboniferous rocks, as well as sub- 
sequently, and that this caused a more rapid sinking of the sea-floor 
on the south (downthrow) side of the fault:—‘ There was lateral 
pressure going on in the crust of the earth, and the result of this 
was to pucker up the ocean-bed into a series of little folds, and here 
and there the sea-bottom was so raised by gradual movements to 
sea-level. Then the first result was the breaking-up by the waves 
of the rock so raised.... A kind of shoal of angular and more or 
less rounded fragments resulted, and in these shoals arose colonies 
of animals to whom such a site was suitable. Slowly these little 
shoals grew up by the continual growth and death of shell-bearing 
and coral-building animals, and their remains were tossed about and 
more or less broken by the waves. The resulting débris bound 
itself together and became a solid limestone-rock.... Now these 
singular deposits differ in their arrangement from all other stratified 
deposits with which we are familiar in ordinary bedded rock-masses. 
They grew, many of them, to a considerable thickness, some to nearly 
50 fathoms in height, but instead of extending indefinitely or 
thinning out gradually, as ordinary strata do, they are very limited 
in their extent, and end abruptly all round in a steep slope. They 
form, in fact, low truncated cones, of which the inner part shows 
rough horizontal bedding, and the steep sides give outward dips all 
round joas: 

‘Tt is obvious that if these knoll-reefs commenced on a shoal 
of fragments broken up by the waves, and grew to 200 or 300 
feet in height from the accumulation of the remains of marine 
animals, the foundation on which they rested must have been 
sinking, so that these animals could still live in that position 
as regards the surface which was most suitable to them, that is, 
within the influence of surface-waves ; and when we get reefs like 
this scattered over wide areas, as 1s the case, we know that over all 
the region containing them the sea-bottom was slowly sinking, and, 
as it sank, the animals kept building up the mounds. Hence the 
horizontal bedding throughout the middle of these mounds, and 
the sloping beds round their edges, which simply represent the 
material, whether the loosened remains of dead animals or wave- 
broken masses, big and little, of the reef, which ran down the sides, 
until they came to an angle of rest...... The cones grew up as 
the bottom went down, until either the top was too narrow to give 
an area of annual growth, or until the rate of sinking was too great 
for the animals to keep pace with it, and the water consequently 
became too deep to support such forms under conditions favourable 
to life.’ * 

I have preferred to reprint this extract verbatim, in order to avoid 
any misrepresentation of Mr. Tiddeman’s views. It is only fair to 
state that there is other evidence which he brings forward in favour 
of his opinion (such as stalagmitic masses in the reef) which I have 
not quoted. I may reter the reader to the original publications for 
further information. 

1 ¢Oraven Herald,’ Jan. 29th, 1892, 


a 


Vol..55.] THE CRAVEN DISTRICT OF YORKSHIRE. 331 


III. Nature oF tHE DistuRBANCES SOUTH OF THE CRAVEN FAULts. 


One of the most suggestive features in connexion with limestone- 
knolls is their occurrence in districts where the rocks have been 
affected by profound earth-movements, so that they present phe- 
nomena analogous to those described by Heim and other writers on 
the highly disturbed sedimentary rocks of Alpine regions. ‘This is 
true not only of the knolls of the Craven district, but also of those 
of all other areas which I have examined, or concerning which I 
have read, as will be seen in the sequel. The number of cases 
where knoll-structure is found in disturbed regions of this character, 
and the fact that no knolls have been discovered in areas where the 
rocks have not undergone intense plication and fracture, is sufficient 
to show that this is no mere coincidence, but that the existence of 
the knolls has some definite connexion with the disturbed character 
of the rocks. 

Although the existence of marked plications affecting the rocks 
south of the Craven Fault has long been recognized (the sharp folds 
of Draughton Quarry, near Skipton, have become classic), the very 
great disturbance of the rocks does not seem to have been fully 
appreciated, chiefly because signs of such disturbance (as is now 
well known) are at a cursory glance less obvious than when the rocks 
have been less disturbed, for in the latter case the middle limbs of 
the folds are intact, and the fold can be seen ; whereas in the former, 
the middle limbs being destroyed and replaced by faults, there is a 
general parallelism of the strata which would lead anyone taking 
a cursory view to suppose that rocks which are really sharply bent 
and repeated form portion of one gentle fold. 

I propose, therefore, to bring forward evidence of the intense 
nature of the movements which the South Craven Lower Car- 
boniferous rocks have undergone. Beginning with the Draughton 
Quarry itself, one finds much more disturbance in the rocks at the 
north end of the oft-figured eastern face than in the rest of the 
quarry. An inspection of the accompanying figure (fig. 1, p. 332) 
will show this. I would also refer those who are acquainted with 
the structure of a district wherein the strata have been much affected 
by lateral pressure to examine figs. 1 (p. 15), 2 (p. 18), 4 (p. 24), 8 
(p. 35), 9 (p. 38), and 11 (p. 39) in the Geol. Surv. Mem. on ‘The 
Geology of the Burnley Coalfield,’ 1875, as samples of the appear- 
ance of the strata. Fig. 4, the section in the railway-cutting near 
Ribchester Station, is especially suggestive. A beautiful section 
showing similar structure is visible in the Hambleton Rock Quarry, 
close to Bolton Abbey Station. Examples might be multiplied, for 
the district abounds with them, but these will suffice to show the 
nature of the folding which the rocks have undergone, and will, I 
think, convince anyone conversant with such structures that we are 
here dealing with a district which has been subjected to great Jateral 
pressure. 

Examination of these sections, suggestive as it is, is only a 
preparation for the information obtainable from detailed study of 
the rock-masses, and I proceed to give some account of these 


332 MR. J. E. MARR ON LIMESIONE-KNOLIS IN [Aug. 1899, 


detailed structures, premising that it is the object of this paper to 
show that the knolls themselves, with their accompanying breccias, 
are directly due to the lateral pressure which has affected the 
district. To a student of the minor structures no section offers 
more information than that exposed in Draughton Quarry, and 
I shali now give some account of the features presented therein. 
The village of Draughton les 3 miles east of Skipton. The 
quarry, which is one of many, may now be readily found, as it is 
close to the church at present in course of erection. It is irregularly 
quadrangular, and, as before remarked, the classic section occurs at 


Fig. 1.—General view of the eastern end of Draughton Quarry. 


[Reproduced from a photograph by R. H. Adie, M.A.] 


the eastern end. The north side nearly coincides with a line of fault ; 
at the western end the folding is less complex than at the eastern, 
while the south side runs parallel with the general strike of the 
beds. Commencing with the eastern end, it will be seen in the 
above figure that there are two sharp anticlines with an intervening 
syncline, and on the left of these are beds dipping northward, which 
seem to form an overfolded anticline with the core faulted, the 
syncline that intervenes between this and the anticline on the right 
being faulted out. I shall speak of the two sharp anticlines as right 
and left, and of the intervening syncline as the central syncline. The 
beds consist of limestones of various degrees of purity, with several 
interbedded shales. Three of these shales are more important than 
the others, and I shall refer to them as the upper, middle, and lower 
shale-bands. The upper shale-band is seen above the highest very 


Vol. 55.] THE CRAVEN DISTRICT OF YORKSHIRE. 333 


thick calcareous band in both anticlines. The middle shale-band is 
separated from the upper by the above-mentioned calcareous band 
(hereafter spoken of as the breccia-band) and another calcareous band 
below it: this shale is also well seen in both anticlines. The lower 
shale is seen in places a little above the top of the débris, in the right 
limb of the right anticline. 
It will be convenient to consider the features of the quarry in 

the probable order of their production, and I will commence with 
a description of the breccia-band.* It appears to form a true bed, 
and may be traced practically all round the quarry at the same 
horizon, namely, immediately below the upper shale. As it 1s 
folded with the other layers, it clearly occurred as a breccia 
before the final folding. It varies in thickness, measuring on an 
average about 3 feet. Where unweathered, the fragments are difficult 
to distinguish from the matrix, both consisting of grey calcareous 
matter ; but on a weathered surface the fragments stand out, and in 
one place the matrix is weathered to a rusty yellow, while the 
fragments remain grey. At the base the brecciais welded in places 
to about 3 inches of unbrecciated rock with parallel structure, the 
junction being irregular, resembling the sutures of the bones of a 
skull, but parallel to the base of the band, and it looks as though 
the lower part of the rock had undergone re-crystallization, although 
it is in places full of foraminifera. In other parts of the quarry 
there is no unbrecciated portion, the band being brecciated to its base. 
The fragments are angular, and very irregular in shape, often 
showing knobs with intervening depressions. ‘The fragments are 
often cracked across, without displacement (see fig. 2), but occasion- 
ally a slight displacement may be seen. Some of the cracks pass 
through the matrix, 

but most of them Fig. 2.—Cracked fragments in breccia, 

do not; and exami- Draughton Quarry. 

nation of the frag- 

ments in the quarry 

convinced me that 

these had not fallen 

into a mass of lime- 

stone after its depo- 

sition, but that the 

brecciation occurred 

subsequently to the 

consolidation of the [About 4 nat. size] 

limestone, as the 

result of rock-movement. Additional evidence of this will be 
subsequently advanced. The alternate ‘bays’ and ‘headlands’ of 
many of the limestone-fragments suggest solution under pressure, 
as seen in fig. 2. 

The top and base of the breccia, and of the other hard bands in 


1 First recognized as a breccia by Mr. Tiddeman ; see Handbook for Leeds 
& Airedale, prepared for Brit. Assoc. Meetg. 1890, p. 52. 


334 MR. J. E. MARR ON LIMESTONE-KNOLLS IN [Aug. 1899, 


the quarry, are marked by intense slickensiding on the bedding- 
planes, and the joints are also frequently affected by horizontal 
slickenside-striations, or striations which were horizontal before 
the folding of the beds. ‘These slickensides show a crag-and-tail 
structure like glaciated roches moutonnées, and the reason for 
this seems to be the same in each case, the rough faces pointing in 
the direction away from the movement. Variation in the direction 
of the movement points to the production of the slickensiding 
before the final folding: that is, to a differential movement 
of the beds with general parallelism to the bedding. In some 
cases, here and elsewhere, one set of slickensides has partly 
effaced preceding slickensides, showing that the movements were 
not always in the same direction, and probably proving the futility 
of an attempt (which I had hoped would be useful) to ascertain 
the general direction of rock-movement by examination of slicken- 
sided surfaces. 

The matrix of the breccia is in places dolomitized. A microscopic 
examination of the breccia shows angular fragments of very fossili- 
ferous limestone set in a granular calcareous matrix. The margins 
of the limestone-fragments show the suture-like irregularities 
seen at the junction of the breccia with the lower unbrecciated 
rock. ‘The sections of the junction between the breccia and the un- 
brecciated base of the band bring out this suture-like appearance 
very markedly. The fragments are to a large extent composed of 
crinoidal limestone, in which the crinoid-remains are seen to be 
embedded in a compact calcareous matrix. The unbrecciated portion 
consists of a limestone composed largely of foraminifera in a erys- 
talline matrix. The foraminifera are in an excellent state of 
preservation, and I believe that we are here dealing with a 
phenomenon which repeats, upon a small scale, what is seen on a 
larger one in the knolls, namely the preservation of fossils where 
there has been relief from pressure, allowing the matrix 1o be 
completely re-crystallized. Hence, notwithstanding the present 
different appearance shown by the limestone-fragments, and the 
matrix of the unbrecciated portion of the band, I conclude that the 
two portions of the rock were originally similar, but that the 
fragments have been practically unaltered by the earth-movements 
which caused re-crystallization of the original rock at the base of 
the breccia-band. 

I have taken the breccia as a datum, as it is the thickest and 
most easily recognizable band in the quarry. I will now proceed 
to describe the structures presented by the more interesting bands 
above and below it. 

Some distance above the upper shale, on the left limb of the 
central syncline (aud no doubt elsewhere) is a dark blue calcareous 
rock: this breaks up along two sets of close-lying subparallel 
divisional planes, which are roughly at right angles one to another, 
into rod-like masses. It also splits up along fine divisional planes 
at right angles to these, and parallel to the bedding, and encloses 
little lenticles of rock which seem to have been dragged out and 


Vol. 55.] THE CRAVEN DISTRICT OF YORKSHIRE. Sa 


bent, so that the rock appears to have suffered compression and 
subsequent stretching. Under the microscope, a section of this 
rock shows that the rod-like masses are separated by very fine 
joints. The rock has been subjected to pressure to so great an extent 
that it exhibits a structure closely resembling flow-structure : in fact, 
it has the mechanical characters of a schist. The fragments of 
organisms are arranged with their longer axes 
parallel to the ribboned lines which have been 
‘developed, and often stream around larger frag- 
ments. The lenticular patches appear to consist 
of portions of the rock which have been more 
completely rolled out than those portions by which 
they are surrounded. 

The remainder of the bands to be described are 
below the breccia. Inthe centre of the middle 
shale is a thin calcareous band, seldom more than 
1 inch thick and usually much less, which is of 
great interest. It is largely composed of crinoid- 
joints, and when at its thickest these are easily 
apparent. It is traversed by wavy lines parallel 
with its top and base, and suggestive of flow- 
structure rather than lamination. When the band 
is thinner, the fossils are less apparent, while the 
divisional planes come closer together and more 
nearly approach exact parallelism. At its thinnest, 
the fossils have almost disappeared, and veins also 
occur along the divisional planes. Microscopic 
sections of the three types have been examined. 
In the first stage the rock is practically a breccia, 
fragments of very fossiliferous limestone being 
surrounded by a matrix consisting of the original 
rock rolled out into a schistose-looking substance. 
In the second stage the fragments have been 
further comminuted, so that only the smallest 
fossils occur in a state approaching perfect pre- 
servation; the matrix has been further dragged 
out into attenuated lenticles ; and the whole struc- 
ture has the mechanical characteristics of a fine 
schist. In the third stage, the slice examined 
showed little beyond the veins of calcite which had 
been developed along the plication-planes of the 
rolled-out rock. 

In the limestone below the middle shale is a 
remarkable chert-band (see fig. 3). It forms a series of lenticles, 
sometimes.in contact, but often isolated. The chert mav have been 
formed in this manner, but its appearance is much more suggestive 
of stretching. It is much veined. Under the microscope it shows 

little of interest, except the calcite-veins which have filled up the 
interstices produced by stretching of the rock. 

The limestone below that containing the chert-band is about 


[A length of about 5 feet is shown in this figure. ] 


Fig. 3.—Chert-band in limestone below middle shale, Draughton Quarry. 


Fig. 4.—Folded limestone in middle shale, arch of left fold, 
Draughton Quarry. 


= A 


Hf a ; ae en 
_ donncs a eee 


1 = Limestone above middle shale. 3 = Limestone below middle shale. 
2 = Middle shale, with thin, broken, x = Position of the portion en- 
and folded crinoidal limestone. larged in fig. 5, below. 


[Scale : 1 inch = 82 inches.] 


Fig. 5.—Enlargement of a portion of fig. 4 at the point 
marked Xx. 


[Seale : 1 inch = 4 inches. ] 


—_- 


Vol. 55.] LIMESTONE-KNOLLS IN CRAVEN. ; 337 


18 inches thick. The major part of the limestone is obviously com- 
posed of fossils, but the uppermost few inches possess a marked 
parallel structure, and the fossils appear to be rolled out, while at 
the base the parallel structure is more marked and no fossils are 
visible to the naked eye. The same remark applies to the chert- 
band limestone. 

A microscopic examination of the base of this rock, and also of 
the base of the limestone containing the chert-band, reveals appear- 
ances which generally resemble those exhibited by the thin limestone 
that occurs in the middle shale. ‘The greater part of each rock 
consists of limestone with a structure resembling flow-structure; 
where this has not been very fully developed the rock exhibits 
a brecciated appearance, and the matrix has a parallel structure, 
the lines of discontinuity ‘ flowing’ around the brecciated fragments. 
The shale-bands themselves show signs of stretching and crushing, 
although no fossils were observed in them. Elsewhere I have found 
similar shales containing Posidonomy« and other fossils which show 
signs of stretching, and are teased out at the edges. 


The phenomena described in the foregoing pages—the breccia- 
tion, slickensiding, rolling out, and stretching—are all explicable 
on the supposition that there was differential movement in the beds 
which at first caused them to slide one over another, the move- 
ments being in general parallel to the original bedding of the rock. 
Following these movements came those which caused the sharp 
folding and minor overthrusts of the rocks, and as the result of 
this phenomena of considerable interest are exhibited. 

In the left limb of the right fold, the breccia is seen to be 
thrust into the upper shale, with much disturbance of the latter, 
though the hard beds above pass over the arch of the fold un- 
broken, the shale having been squeezed out against the breccia and 
collected in the hollow below. In the trough of the central syncline, 
two thin beds of shale above the upper shale have also undergone 
much movement, being squeezed into a hollow in the trough, and 
thin hard beds in them are folded and broken. But the most 
interesting feature is shown in the case of the middle shale, in the 
arch of the left fold. The limestones above and below have been 
stretched, and are traversed by radial and tangential veins, while 
the shale with its central thin lmestone has been squeezed away 
from the sides of the fold, so that the limestone is in places absent 
there, and the shales are very thin. At the arch the shale is 
puckered up and thickened, and there seem to be several bands of 
limestone, which on examination prove to be the folded and broken 
portions of one (see fig. 4). On the right-hand side of this fold, 
about 4 feet below the crest of the arch, a remarkable hollow in the 
limestone (possibly caused by solution under pressure) is filled with 
arched-up shale; the thin central limestone is repeated thrice on 
itself by faulting; and fragments of it occur detached from the main 
mass (fig. 5). I cali special attention to this occurrence, because it 
constitutes a minute representation of knoll-structure, showing all 


Ord.G.s, No. 219. Z 


338 MR. J. E. MARR ON LIMESTONE-KNOLLS IN [ Aug. 1899, 


the features which are observable on a larger scale—the thickening 
of the limestone where pressure bas been relieved, and its thinning 
at points where pressure was greater; the level ‘stratification ’ of 
the centre of the knoll and its arching on the exterior; the forma- 
tion of breccias around the knoll, and the arching of the shale over it. 

So much for the lessons tanght by an examination of Draughton 
Quarry, which I have described in detail, on account of the interest 
that attaches to the quarry in consequence of its frequent description. 
It is not to be supposed that the phenomena displayed here are local ; 
they and others akin to them may be studied abundantly in the'sh ales 
with thin limestones south of the fault-system, and they illustrate 
in a marked manner the changes which have taken place as the 
result of earth-movement in the rocks south of the fault. 


IV. Description oF THE KNOLLS NEAR CRACOE AND SETTLE, AND 
Notes on Kwobi-stRuctuRE. 


A group: of knolls, which I had the advantage of first seeing 
under the guidance of Mr. Tiddeman, rises near Cracoe, west 
of the Millstone Grit escarpment of Cracoe and Thorpe Fells. 
The knolls run on lines roughly parallel to the escarpment, but 
they also have a somewhat irregular arrangement into groups; one 
such group occurs immediately west of the escarpment, each knoll 
forming a hill. Although each knoll forms an eminence, it does 
not follow that the limestone of each is absolutely severed from that 
of the surrounding knolls, and indeed only one (Stebden knoll) is 
represented on the Geological Survey map as isolated from the 
limestone by shale-bands; but the structure of the ground makes it 
highly probable that the overlying Bowland Shales abuthed against 
the upper portions of each knoll. 

The general characters of the knolls have already been noticed in 
the extracts which I have given from Mr. Tiddeman’s writings, a 
prominent feature being the horizontality of the interior, the general 
parallelism of the bedding of the exterior to the contour of the 
knoll, and the obscurity of the bedding. ‘The Cracoe knolls are 
largely grass-covered, and nothing lke a complete section through 
a knoll is obtainable. The variations in the direction of bedding, 
however, recall the structure described by Prof. Bonney as pseudo- 
stromatism, often upon a large scale, and signs of folding accom- 
panied by fracture are not wanting, though it would be difficult in 
the case of these knolls to convince anyone that this structure was 
really due to extensive earth-movements. The same is true in the 
case of the Settle knolls, and those at Downham, near Clitheroe, 
which I have also examined, and therefore I propose to supplement 
my description of these groups of knolls by some general notes upon 
knoll-structure. 

Mr. Tiddeman describes the knolls as formed of ‘ white to grey 
crystalline limestones of irregular form, and less visible bedding 
[than that of the black limestones] except in the mass and on the 
sides of the hills of which they consist.’ They ‘are crammed with 


" 
oy Mi ’ \ 
‘ S 7 | 


Quart. Journ. Geol. Soc. Vol. LV, Pl, XXIV. 


raversi 

The fault-es¢ | 
| : 

| | 

. | 

| 

/ 


Volhs 53] THE CRAVEN DISTRICT OF YORKSHIRE. 339 


brachiopoda, lamellibranchs, crinoids, corals, etc., many fairly 
perfect.’* The crystalline nature of the limestone and the frequent 
abundance of fossils in a beautiful state of preservation is, so far as 
I know, a characteristic of knoll-structure not only in the Craven 
district, but elsewhere, and it has been justly pointed out to me 
that, if the knolls were formed owing to marked earth-movements, 
the perfection of the fossils is somewhat remarkable. The fossils, 
however, are distributed in a very sporadic manner; we often find 
great masses of white crystalline limestone crowded with organisms, 
‘while at other times similar limestones are apparently unfossili- 
ferous. This holds good of all areas in which I have examined 
knoll-structures. Sometimes a knoll is fossiliferous throughout, at 
others unfossiliferous, while we often find parts of one knoll crowded 
with fossils, and other parts of the same knoll yielding none. Now, I 
shall endeavour to show that the knolls were formed where there was 
relief from pressure, and as the result of this relief the crystalline — 
structure was developed, and the fossils were either destroyed, or, if 
not destroyed, did not undergo distortion. 

The Settle knolls ? occur immediately south of the Middle Craven 
Fault, and are seen as a series of eminences between Settle, on 
the west, and the head of the Stockdale Valley on the east, where 
the Millstone Grit abuts against the Scar Limestone north of the 
fault ; but a similar set of knolls is found against the fault in the 
Malham Valley. ‘These knolls, like those of Cracoe, are arranged 
with a general linear trend, in this case parallel with the fault, though 
they also occur in somewhat irregular groups. The structures ex- 
_ hibited by them are similar to those seen at Cracoe, and no further 
description of them is necessary at this point. A view of the knolls, 
with the fault-escarpment in the background, is reproduced in 
PI. XXIV, facing this page. 

I will now adduce various kinds of evidence in favour of the 
formation of knolls as the result of marked earth-movements and 
rock-folding. 

- [ have already described in detail the production of a structure 
analogous to knoll-structure, and indeed, in my opinion, one which 
is knoll-structure on an almost microscopic scale, in a thin limestone 
interbedded with shale in the left anticline of Draughton Quarry 
(p. 337). From a structure of this size all gradations may be traced 
to the large knolls which sometimes rise to a height of 400 feet, and 
in the case of the smaller knolls there is naturally more opportunity 
of studying the characters than when viewing large knolls which 
frequently only exhibit superficial exposures, or, at best, sections 
through portions of the knoll. Study of the smaller knolls shows 
that they often vary in detail, but the general plan is the same; 


1 Rep. Brit. Assoc. 1889 (N’castle-on-Tyne) p. 602. 

2 It is due to Mr. Tiddeman that I should state here that the Cracoe and 
Downham knolls are the only knolls that I have examined which Mr. Tiddeman, 
to my knowledge, has accepted as his ‘ reef-knolls.. I do not know whether he 
would admit the Settle structures as such, though I endeavour to show that 
they are similar to those observed in the neighbourhood of Cracoe. 


zZ2 


Quart. Journ. Geol. Soc. Vol. LV, Pl, XXIV. (Zo face p. 339. 


KNOLLS weAR SCALEBER, SETTLE. 


[From a photograph taken by E. J. Garwoop, M.A., F.G.S.] 


The fault-escarpment of Attermire Scar is seen in the background. Shales underlie the grass in the foreground. A small knoll, in part quarried, is traversed by the road ; 


behind this is a larger knoll, and, to the right of the second, a third knoll shows its summit. 


xo: 


- 
ha s 


Rk PRAY . 


— 340 MR. J. E, MARR ON LIMESTONE-KNOLLS IN. [Aug. 1899, 


they consist of repetitions of hard bands of limestone situated 
between shales, the repetition being sometimes due to folding 
accompanied by faulting, and sometimes to faulting alone. In the 
summer of 1897 an almost circular knoll, about 4 feet in diameter, 
was exhibited at the eastern end of the Hambleton Rock Quarry at 
Bolton Abbey Station: it is clearly the result of the thickening out 
of a single band of limestone. In the Otterburn Valley, east of 
Long Preston Station, a number of knolls of small size may be seen 
in plan and section, and in some cases traced to the expansion of 
thin beds of limestone. There are many other localities where 
similar phenomena occur, and these small knolls, like the large knolls, 
are often associated with breccias. In some of theshales surround- 
ing the small knolls of the Otterburn Valley, the rock breaks up 
along divisional planes at a high angle to the bedding, the planes 
are close together and parallel one to another, and J cannot distin- 
guish the structure from cleavage. 


Fig. 6.—Folded (2), faulted, and brecciated limestone-band, 
Winterburn Reservoir. 


Sor sBasa Jy oom 


[The above diagram is an attempt to show one band only. Length of 
section = a few feet. | 


The structure cannot be well brought out by photography, and 
drawings are of little use, as the draughtsman will probably delineate 
more than he sees. It is difficult, therefore, to convince anyone 
who has not inspected the district of the repetition of beds, for 
generally simple overfolding is absent, and thrusting is the rule ; 
nevertheless the termination of lenticular masses of limestone in 
loops against a divisional plane is sufficient to indicate where repeti- 
tion has occurred, and this structure is frequent. To explain what 
I mean, I reproduce here from my note-book a section of part of a 
knoll of white crystalline limestone, exposed in making the reservoir 
at Winterburn (and now, alas ! submerged), which was shown to me 
by Mr. Tiddeman in the year 1888 (fig. 6). This I take to bea 
case of repetition of a thick band of limestone upon itself several 
times, the limestone becoming brecciated on the right of the section, 
but it is only fair to state that some who saw the section would not 
admit this explanation, and Prof. J. Walther, who admitted the 
folding, attributed it to drag of the edge of areef. Very significant 
also is the appended section (fig. 7), taken from an exposure of 
limestone several yards high in the Otterburn Valley, near Long 
Preston, which shows what is almost certainly a case of pseudo- 
stromatism. (I may here observe that in many sections, where the 


Volzg5:| THE CRAVEN DISTRICT OF YORKSHIRE. 341 


succession of the limestones appears regular, any individual band 
is found upon inspection to be lenticular, and to die out in a few 
yards, so quickly, indeed, that it is hardly possible to suppose that 
one is examining lenticles produced by deposition.) 

I have various notes of folded structures in knolls formed of white 
crystalline limestones in other areas, as for instance in the Ordovician 
limestones of Keisley and Millom. 

Though knoll-structure is best developed in limestone, it, or an 
analogous structure, is not absent from other hard rocks, such as 
grits. Small examples of incipient knoll-structure in grits are 
visible in the section by the canal-bank below Skipton Castle, though 
the best examples of grit-knolls that I have seen are found in the 
Middle Devonian rocks of Hagginton Beach, and the bathing-place at 
Ilfracombe in North Devon. This structure is especially important, 
as in this case there is no question of its production as the result of 
accumulation of organic remains under special circumstances. 


Fig. 7.—Pseudostromatism (7) in limestone, Otterburn Valley. 


te 
2 oe 


[The above is a diagrammatic view of a quarry-face, showing the apparently 
lenticular beds of limestone. ‘This rapid alternation, however, seems to 
be due to faulting along fissures which are but slightly inclined to the 
bedding-planes, when they do not coincide with those planes. ] 


Two types of rock are frequently associated with knolls of lime- 
stone, and the association is probably of some significance, as it 
indicates the occurrence of chemical changes which might readily 
take place during the exertion of pressure: I refer to dolomites and 
silicified limestones. Dolomitized limestone is found in association 
with the other limestones of the Cracoe and Settle reefs, and fine 
examples of silicified limestone are found in some reefs at the head 
of the Stockdale Valley, east of Settle. The latter are specially 
noteworthy, on account of the crystals of quartz which they contain 
when the silicification is incipient. In other parts it is complete. 
The silicification here seems identical with that recently described 
to the Society by Mr. Arnold-Bemrose.’ 


* Quart. Journ. Geol. Soc. vol. liv (1898) p. 169. 


[aang [oH “§'A (26-1681) dey ‘uuy wygT “taox “Id 
eanjoniyg uviqoureddy jo sovavysop , oy} uo saded ssi Aopreg wosf paonposdoy | 


Vol sisi LIMESTONE-KNOLLS IN CRAVEN. 3435 


A microscopic slice from the rock at the head of Stockdale, 
where silicification has commenced, shows abundant crystals of 
smoky quartz which often display a zoned structure. The perfection 
of the crystals suggests a peculiar condition of matrix during the 
time of their formation, and seems to bear out the observations hich 
I have made concerning the limestones of the knolls, that their 
crystallization was due to removal of pressure, and that they were 
in a quasi-fluid state before their final consolidation. 

It is interesting to find dolomitization and silicification recorded by 
Mr. E. B. Wethered! in the limestones of Barton and Lumiaaton, 
near Torquay, which are in every respect similar to those of the 
knolls of Craven, and themselves exhibit knoll-structure. 

One other piece of evidence bearing upon knoll-structure yet 
remains to be advanced, and that is its artificial production by 
lateral pressure. The figure facing this page (fig. 8) shows the result 
of one of many experiments made by Bailey Willis, and is copied from 
the 13th Annual Report of the United States Geological Survey 
(1891-92) pl. xcvi. The knoll is complete, even to the production 
ot brecciatiun at the margin. 


V. Tar Brecctas. 


Associated with the reefs are several kinds of breccias, which 
have undoubtedly been formed in more ways than one. In the first 
place, ordinary fault-breccias occur, consisting of angular fragments 
of limestone, usually embedded in veined orystallane ene such 
as the breccia seen at the extreme left of the eastern end of 
Draughton Quarry. These breccias were probably produced at a 
late period of the movements which have affected the rocks, the 
particular breccia at Draughton not being anterior to the production 
of the sharp-folds. 

Of other breccias one may find three principal varieties :—(i) frag- 
ments of limestone in a limcstone-matrix, the fragments having 
the same general composition as the matrix; (11) large nodules of 
black limestone of irregular form, set in shales of which the divi- 
sional planes frequently sweep round the fragments; (111) angular 
and frequently rounded fragments of various kinds of limestone 
in a fine calcareous paste, the rock in some cases resembling a 
conglomerate, and the fragments and paste usually breaking across 
with equal ease. I believe that all these varieties have been 
produced as the direct result of earth-movements, that they are in 
fact fault-breccias, and I propose to consider each kind in turn. 

Of the first kind I have referred to two examples, one in the 
Draughton Quarry, p. 333 (see also fig. 9, p. 344), and another at 
Winterburn (p. 340). I have given reasons in each case for supposing 
that the breccias were produced by movement, in the first instance, 
as the result of simple fracture of a limestone- band between two 
others moving along bedding-planes at different speed, and without 


* Quart. Journ. Geol. Soc. vol. xlviii (1892) p. 377. 


344 MR, J. E. MARR ON LIMESTONE-KNOLLS IN [ Aug. 1899. 


any incipient folding; in the second case as the result of folding 
carried to excess, and the consequent severance of fragments of the 
rock. In the latter case the breccias are naturally distributed more 
irregularly than in the former, where the breccia seems to form a 
true bed, as indeed it is, though, according to my view, in an altered 
condition. These breccias are apt to occur in the knoll-limestones, 
while the other kinds are found in the deposits mantling round the 
knolls. 


Fig. 9.—Limestone-breccia, Draughton Quarry. 


[Reproduced from a photograph taken by R. H. Adie, M.A.] 


The reason for brecciation of some limestone-bands while others are 
unbrecciated appears to be illustrated by the state of limestone-bands 
in a disused quarry on the south side of the Skipton road, just outside 
the village of Draughton, on the way to Skipton. Here some of the 
bands of limestone show incipient brecciation, and where the action 
has not commenced these bands are seen to be affected by very close 
iwregular jointing at right angles to the bedding: moreover, they 
possess lines parallel to the bedding which are either lamination- 
planes or joints. These limestones would naturally break up into 
fragments when affected by earth-movement, while the more massive 
limestones with joints remote one from another might well escape 
brecciation. | 

Breccias of this type are well exposed in the great quarry on the 
right bank of Dale Beck, Ingleton, between the two branches of the 
Craven Fault. In one place a band between the other beds, which 
is about 30 feet thick, shows various stages of brecciation. Near 


Vol. 55.] THE CRAVEN DISTRICT OF YORKSHIRE. 345 


its base is a thick band having a mottled appearance where un- 
weathered, but the weathered part shows that it is a veritable 
breccia. In section, it shows the suture-like edges of the fragments, 
and the schistose structure of the matrix which has been noted in 
the case of the Draughton breccias. A little above this is a foot or 
more of grey pasty rock resembling shale in appearance, but pro- 
bably crushed limestone, with angular and even rounded fragments 
forming a true crush-conglomerate. Much horizontal slickensiding 
is seen through this breccia, as well as along the bedding-planes of 
limestones in various parts of the quarry. 

The breccias formed of irregular lumps of limestone occurring in 
shale seem to 


me to have Fig. 10.—Limestone, broken along joints, with de- 
been also : 


: tached fragments on the right hand, Otterb 
produced in Pili. g right hand, Otterburn 


two ways. 
In the first 
place, bands 
of limestone 
may become 
torn apart, 


and form iso- 4). 
lated patches. Fig. 11.—Folded limestone and breeciated fragments, 


Fie shows Otterburn Valley. 
a band of 


limestone 
near Pot- 
house, Long 
Pere sit on, 
which is 
erma-exk ed 
across along 
joints,and the 
fragments are slightly separated on the left side, the interstices being 
filled with veins of calcite, while on the right actual separation has 
occurred, and the shales sweep in between the fragments. Breccias | 
of this nature would naturally be formed where thin limestones 
with shales were stretched, as the limestones would resist stretching 
more than the shales, which yield frequently along the lamination- 
planes, and also have their particles flattened out. In this case the 
teazing-out of fossils may be frequently observed on the surfaces of 
the shales. In other cases passages are observed from thin lime- 
stones, in shales which have been folded and faulted, into detached 
fragments of limestone, the resulting breccias being produced by 
stretching along portions of rock which have been locally compressed. 
Fig. 11 shows a detached fragment of limestone close to the end 
of the bed from which it has been torn, with a loop due to 
folding, and smaller fragments above. In fig. 12" (p. 346) a breccia 


1 This figure is reproduced from a photograph taken by E. J. Garwood, M.A., 
F.G.8. A fault runs obliquely down from near the centre towards the left-hand 


an 


“apniagy “avo tagaqnag Jo ysva ‘p002.09 Burwusos 


aJDYS UL AUOPSIWAY Y2P)0J— EZ] SLT 


Vol 55.. | LIMESTONE-KNOLLS IN CRAVEN. 347 


is seen exposed in a stream a few hundred yards east of Scaleber 
Force, near Settle. Of this section, which is many yards in height, 
Mr. Garwood wrote :—‘ On ascending the cliff close to the ‘ crush ’ 
I found a clear fault, and any amount of augen-structure and 
ausweichungs-clivage. Besides the nodules I find that large 
Producte have been rolled up into ‘ eyes’ in a similar way.” The 
outlines of the fragments in these breccias are also frequently 
suggestive of partial solution. 

The third type of breccia, which was also formed in the sub- 
merged part of the stream at Winterburn Reservoir, is by far the 
most suggestive of deposition, approaching in many respects a 
conglomerate. Even here, however, the evidence for crush-breccia- 
tion is strong. The ‘ pebbles’ tend to run in irregular lines, which 
are not straight, and thus one may find an irregular row of dark, 
followed by another of hghter pebbles. In some of them central 
fissures run part of the way through the fragment, as though this 
were a portion of a small fold, and many of the fossils embedded in 
the rock are much broken. 

The rock from the stream (Waygill) running into Winterburn 
Reservoir shows in section very much the same characters as the 
breccias which have been previously described. The suture-like 
margins, due to solution under pressure, are very distinct, and the 
matrix presents in places the schistose structure. Fragmeuts of 
chert enclosing small spherical bodies are abundant. 

Fig. 13 (p. 348) represents the polished surface of a fragment 
of this Winterburn breccia. 

On examining a polished surface of another variety of the Win- 
terburn breccia, the evidence for tolding seems to me convincing. 
The pebble-like masses in nearly every case show a central lenticular 
portion filled with the matrix of the rock, which has here undergone 
somewhat more squeezing than it has outside these pebble-hke 
masses, but the fragments of crinoids are readily recognizable in it. 
The indented surface of the inner portion of the ‘pebble’ against 
this matrix is quite similar to that seen in the inner parts of loops 
due to folding; this indented structure seems to be due to solution 
when pressure was great. In some examples of the Winterburn 
breccia, the lenticular portion is not isolated, but communicates with 
the general matrix outside the ‘pebble.’ If these pebbly frag- 
ments were ordinary epiclastic pebbles, I fail to see how the lenti- 
cular mass of matrix in the interior can be accounted for, though 
its evidence is completely in accord with the origin of the pebbles 
as cataclastic structures. 

It will be noted that there is no great difference in the mode 
of origin of the three kinds of breccia, and intermediate examples are 
often found. As in the case of the knolls, so in that of the breccias, 
we find structures analogous to those in the calcareous rocks, 


bottom corner. On the right of this is the folded limestone, which is thrown 
into a number of complicated curves, often accompanied by sinall thrust-faults, 
This causes the brecciated appearance of the rock, as seen in the figure, 


—_ __ —_— — 


"D1000d 


q 


U 


Lng 


LOQUL AY 


6 


hyqqad 


b) 


fo waurdodg— 


& 


iL 


anes 


Vols 5:1 LIMESTONE-KNOLLS IN CRAVEN. 349 


formed of arenaceous rock. I have notes of a grit-breccia in the 
canal-bank at Skipton, and also in Little Newton Gill, near Long 
Preston. 

The production of breccias which frequently simulate conglo- 
merates as the result of earth-movement is now well established. 
Many years ago I published some notes on rocks which often show 
a brecciated structure of this character, occurring in the neigh- 
bourhood of Ilfracombe," and Mr. Lamplugh’s paper on the crush- 
conglomerates of the Isle of Man,” where the author quotes other 
cases of somewhat similar structures, will be fresh in the memory 
of Fellows of the Society; in the discussion I mentioned the 
discovery by Mr. Harker and myself of crush-breccias having similar 
characters in the Ordovician rocks of Lakeland. 

I need hardly say that, as with the knolls, so with the breccias, 
actual inspection of the sections is much more important than 
examination of the evidence yielded by hand-specimens, diagrams, 
and reproductions of photographs. 


VI. CoMPARISON oF THE DEPOSITS ON BOTH SIDES OF THE Favtts. 


On p. 328 is tabulated Mr. Tiddeman’s correlation of the 
deposits on the two sides of the fault-system. It has been made by 
one who has devoted many years of his life to detailed mapping of 
the Carboniferous rocks, and is therefore not lightly to be set aside. 
Nevertheless, | venture to make a few remarks upon the subject. 
As the type of rock suddenly changes at the faults, the correlation 
cannot be the result of actual tracing of the beds from one area into 
the other. Nor can it altogether depend upon paleontological 
evidence, for the faunas of the beds on the south side of the faults 
seem to differ markedly from those on the north side. Lithological 
characters may furnish some clue, even though it be admitted that 
they differ greatly in the two areas. 

It is an interesting fact that the limestone-fauna of the area 
south of the faults is far richer than that of the district on the 
north side, but experience leads me to state that as a rule limestones 
in an area that has been subjected to orogenic disturbances of 
the type which, according to my view, gave rise to knoll-structure, 
are richer in fossils than those that have undergone epeirogenic 
movements only. ‘ Richer in fossils,’ I have written, but the state- 
ment should be qualified, and the term ‘richer, in fossils which can 
be readily extracted in a perfect state, substituted. The horny 
and compact limestones of a district are often seen to be crowded 
with fossils, which are exposed in cross-sections when the rock is 
fractured, but these fossils can be rarely extracted so that their 
specific or, In many cases, even generic characters can be deter- 
mined, and consequently the fauna of a rock which is seen 
to be entirely formed of organisms of various kinds may remain 
practically unknown. The instinct of the fossil-collector which 


1 Geol. Mag. 1888, p. 218. 
* Quart. Journ. Geol. Soc. vol. li (1895) p. 563. 


350 MR. J. E. MARR ON LIMESTONE-KNOLLS IN [ Aug. 1899, 


leads him to return to the lccality known to be rich in fossils, and 
to avoid the apparently barren region, tends to emphasize the 
difference between the fossiliferous characters of such limestones 
as those found north and south of the Craven Faults. The con- 
sequence is that the fauna of the limestones north of the faults, 
whose order of succession is well established, is little known, while 
those of the area where the succession is obscure are well repre- 
sented in all our principal museums. In 1895, Mr. Garwood and 
I urged the appointment of a British Association Committee to 
study the possible zonal distribution of the Carboniferous fossils, 
and as this Committee has now been appointed and is at work we 
may expect important results to follow at no distant date. In the 
meantime, the list of fossils collected from the Lower Scar Lime- 
stone north of the fault is meagre, and there are practically no 
fossil-lists of the faunas of the individual limestones that occur 
between the top of the Lower Scar Limestone and the base of the 
Millstone Grit. I have been led to make these remarks, because I 
do not feel that it has been proved that the Shales-with-limestones 
and the Pendleside Limestone south of the faults are necessarily tine 


equivalents of portions of the Lower Scar Limestone Series on the » 


north. 

I believe, however, that one point is clear: namely, that the 
fauna of the knolls immediately under the Millstone Grit escarp- 
ment at Cracoe is identical with that of the knolls by the stream 
above Scaleber Force at Settle. Individuals of species after species 
may be hammered out of the limestones of one of the knolls near 
Scaleber identical with those found on the flanks of Stebden knoll 
near Cracoe. This is a matter of considerable importance, because 
in each case the limestone that furnishes the fossils is separated from 
the Millstone Grit by a single deposit of shales, and there is no fault 
between the limestones, shales, and grits. If this be so, some of 
the limestones of the knolls, which are referred by Mr. Tiddeman 
to the Pendleside Limestone, may well be equivalent to the Upper 
Scar Limestone of the district north of the fault: in that case the 
lithological characters of the divisions in the two areas would coincide 
more closely than if the classification adopted by Mr. Tiddeman were 
correct. | We should have :~— 


SoutH SIDE. Norru SIpe. ’ 
Millstone Grit. Millstone Grit. 
Bowland Shales. Shales above Upper Scar Limestone. 
Pendleside Limestone. Upper Scar Limestone. 
Shales-with-limestones. Yoredale Shales with limestones. 
Clitheroe Limestone. Lower Scar Limestone. 


Another point requires consideration. If my interpretation of 
knoll-structure be correct, it is not always necessary that one 
limestone be repeated upon itself. In some instances, at any rate, 
two or three limestones might compose a knoll, portions being thrust 
through the intervening shale, in which case a mingled fauna might 
exist in the knolls. This cannot be ascertained until we are placed 


ons a 


Wolly 55.) THE CRAVEN DISTRICT OF YORKSHIRE. 301 


in possession of a much larger mass of evidence concerning the distri- 
bution of Lower Carboniferous fossils than that which is now at 
our disposal. 

If the foregoing correlations could be proved correct, and my views 
of the structure of the district south of the fault were established, 
the deposits which now occur on opposite sides of the fault may 
have been continuous, and generally similar in thickness, lithological 
conditions, and fossil contents: and the present differences would be 
due, as regards thickness, to repetition of strata on the south side, 
and, as regards lithological characters and fossil contents, to changes 
in the characters of the rocks produced by orogenic movements 
acting subsequently to the deposition of the strata. 


VII. Naturs oF THE MovEMENTS WHICH HAVE AFFECTED THE 
Rocks soUTH OF THE CRAVEN FAvtts. 


Owing to the general north-and-south trend of the main axis of 
the Pennine Chain, and the east-and-west trend of an anticline 
running from Morecambe Bay to the Dales district of Yorkshire, 
the coalfields of the North of England have a cruciform arrange- 
ment, the Cumberland and South Lancashire coalfields lying on the 
west of the Pennine axis, and the Northumberland—Durham and 
Yorks—Notts—Derbyshire coalfields on the east, while the Cumbrian 
and Northumberland—Durham fields lie north of the east-and-west 
anticline, and the other two south of it. It is true that the 
symmetry of this structure is partly destroyed by the existence of 
the Lake District dome, which, as I hope to show elsewhere, is of 
much later origin than the structures that we are considering. 

The Craven system of faults seems to be clearly connected with 
this east-and-west anticline, and certainly with complications of it, 
causing the rocks on the south to be thrown into minor folds, 
which have axes running in a general north-easterly and south- 
westerly direction. As the Craven Faults also separate the two 
types of area considered in the foregoing pages, it is necessary to 
devote some attention to the character of those faults. 

Are the Craven Faults thrust-faults? The cessation 
of knoll-structure to the north is determined by the Middle Craven 
Fault, by far the most important of the system, and it is necessary 
to examine the trend of this fault in order to arrive at a conclusion 
as toits nature. First, we may consider its outcrop at the surface. 

In its course from near Ingleton to beyond Gordale, it crosses 
important valleys at Ingleton, Clapham, Austwick, Settle, and 
Malham. At Ingleton, the phenomena displayed by the rocks in 
the large quarry on the west side of Dale Beck are certainly sug- 
gestive of thrusting over the Coal Measures. 

[In connexion with this matter, the occurrence of a deposit of 
crushed coal, apparently interstratified with the limestones, in the 
great quarry by the side of Dale Beck, deserves notice. This coal 
thins out and disappears, when traced upward along the face of the 


352 MR. J. E. MARR ON LIMESTONE-KNOLIS IN [ Aug. 1899, 


quarry. It seems highly improbable that the coal is truly inter- 
stratified with the marine limestones, and I consider that the most 
probable explanation of its occurrence is that the limestone has 
been thrust over the Coal Measures beneath, and that the coal has 
been squeezed up between two bedding-planes of the limestone. 

South of the coaly band is a great belt of breccia which 
seemed to me to give indisputable proof of its formation by earth- 
movements. The beds in its vicinity are much marked by slicken- 
sides on their surfaces.— April 26th, 1599. | 

The Clapham Valley I have not recently seen; so far as I 
remember, the scar runs some distance up the valley. This is 
certainly the case at Austwick, where the fault is mapped in a blunt 
V, of which the apex points up the beck, the apex being more than 
4 mile north of the direct line of the fault on either side of the 
valley. 

The crossing of the Ribble at Settle requires further consideration. 
On the Geological Survey map, the apex of the V points down the 
valley, in which case the hade of the fault would be normal. Exami- 
nation of the area shows that the continuous scar which, I believe, 
marks the boundary of the fault, runs far north of this along the 
Settle and Beacon Scars (Attermire Scars), and so to the Ribble 
between Settle and Langcliffe, and on the west side of the valley runs 
at the back of the hill above Giggleswick, thus cropping out with a 
V-shaped outcrop, of which the apex points up the valley. South 
of this line, much limestone occurs on the hill immediately behind 
Giggleswick, in the Ribble, and on the hills between the Attermire 
Scars and their continuation, and the southern bank of the Stockdale 
Valley, but this limestone possesses knoli-structure, and has yielded 
fossils which are practically identical with those of the Cracoe 
knolls. At Malham the same occurrence is observed, the scar 
sweeping up the valleys of Malham Cove and Gordale, while on the 
south is limestone showing knoll-structure. The Middle Craven 
Fault, in fact, appears to be a thrust-plane, inclined downward 
towards the north, and, judging from the Austwick outcrop, the hade 
of the fault makes but a small angle with the horizon. 

In support of this view, I may point to the nature of the throw. 
All the way from Ingleton to Gordale the Scar Limestone occurs 
on the north side of the fault. On the south side Permian beds 
occur west of Ingleton, Coal Measures at Ingleton, different members 
of the Millstone Grit from here to beyond Settle, Lower Carboni- 
ferous rocks west of Settle, Millstone Grit again east of this, and 
Lower Carboniferous rocks once more in the Malham Valley. 
This disposition can be partly, but not altogether, explained east of 
Settle by ditferences in the level of the fault-outcrop; but this will 
not account for the actual occurrences along the rest of the line 
where the country is fairly level. The beds on the south side are, 
in fact, thrown into a series of folds, these folds are abruptly cut 
off by the faults, and do not recur on the north side, where 
the beds are almost horizontal at a little distance from the fault. 
As the folds to the south are cut off abruptly by the fault, they 


Vol. 55.} THE CRAVEN DISTRICT OF YORKSHIRE. 35 


were formed prior to the fault, and accordingly their continuation 
ought to be traceable to the north (which is not the case) if the 
fault were normal; if the fault be a thrust, the disposition of the 
rocks is perfectly explicable, as I shall proceed to show in greater 
detail. 

The east-and-west anticline has its centre immediately north of 
the Craven system of faults, where the Lower Paleozoic rocks are 
exposed at the surface. If the folding were simple, one would 
expect the minor folds to have axes coinciding with the major folds, 
which is not the case. The northern edge of the Burnley Coalfield 
and the southern edge of the Millstone Grit mass of the Fells near 
Lancaster trend in a general north-easterly and south-westerly 
direction, and between them is the anticline, broken up into still 
smaller folds, in which the knolls occur. Now the Craven Fault 
system has its greatest throw on the west, and dies out to the east; 
accordingly, if the movement be one of thrust from the north, the 
beds below the thrust should be moved southward to an ever- 
increasing extent as we pass from east to west, and beds which once 
had an east-and-west strike would in that way acquire the strike 
that they now possess, namely, east-north-east and west-south-west 
near Cracoe, and north-east and south-west to the west of this. 

As corroborative evidence of the nature of the fault, I may 
remark that, if my interpretation of the structures south of the fault 
be true, these structures require thrusting to account for them. 
This remark may appear like arguing in a circle, but the whole of 
the evidence must be considered together. 


Whatever be the nature of the folding south of the faults, we are 
all agreed that the rocks are thrown into a series of anticlines and 
synclines the axes of which vary from north-east and south-west to 
east-north-east and west-south-west. In the saddles of these axes: 
the Lower Carboniferous rocks and knolls are found, in the troughs 
the Millstone Grit; furthermore, the knolls do not occur singly in 
each anticline, but in clusters, having a general linear arrangement, 
and also a subsidiary irregular grouping. The reason for this 
disposition may now be discussed, and I offer the following remarks 
as worthy of consideration. 

Between the comparatively rigid Millstone Grits above, and 
the Lower Paleozoic rocks below, lie the yielding Clitheroe Lime- 
stones and still more yielding group of shales and limestones above 
these. The formation of the folds with north-easterly and south- 
westerly axes must have resulted in the accumulation of the rigid 
Millstone Grits above in great masses into the synclines, and their 
dragging away from the tops of the anticlines. Accordingly, we 
find horizontal slickensiding by no means rare in the Millstone 
Grits of the Lancaster fells. There may have been actual rupture 
of the Grits at the top of the arches, but in any case there would 
be relief of pressure there, causing the limestones to be squeezed out 
from below the synclines and to accumulate in the anticlines, and 
I believe that it is in this way the knoll-reefs were formed, while 


Q.J.G.8. No. 219. 2A 


304 MR. J. E. MARR ON LIMESTONE-KNOLLS IN [Aug. 1899, 


the minor faults which would inevitably accompany repetition of 
the strata are marked by breccias differing in character according 
to the nature of the rocks in which they were formed. If my 
views be true, we are dealing with a great group of yielding strata 
sandwiched in between two more rigid rock-groups, and all affected 
by the thrusting of other strata over them from the north. The 
result would be that the lower rigid strata would be slightly affected, 
the upper greatly so, but owing to their rigidity they would be 
packed in great blocks, rather than twisted and torn into small 
fragments ; while the central groups of yielding deposits, rolled 
between these others, would be twisted and torn in every direction, 
and would tend to accumulate in the places where downward 
pressure was relieved, and to be squeezed from those where it was 
greatest, just as I said was the case with the little ‘ model’ knolls in 
the left arch of Draughton Quarry (p. 337). 

This hypothesis appears to me to account for all the phenomena 
that I have seen in the area south of the Craven Fault, and to 
furnish a connected explanation of them which is not at variance 
with that given of similar districts elsewhere, or with our knowledge 
of the effects of epeirogenic movements in general. 


A few words concerning the age of the movements which I believe 
to have been responsible for the formation of the knolls may be 
inserted here. The great anticline which is affected by the Craven 
Faults is post-Carboniferous and pre-Permian (using the term ‘ pre- 
Permian ’ with reference to the Permian rocks which occur on the 
east side of the Pennine Chain, for the Coal Measures are affected 
by the fold, and the Permian rocks are not). The Craven Faults 
are subsequent to this, and they affect the Permian rocks which 
occur near Westhouse, lying upon the Coal Measures of the Ingleton 
coalfield. How long a time elapsed after this Permian breccia 
was deposited before the faulting took place we cannot say, but the 
general character of the movement, and the resemblance of the 
consequent phenomena to those exhibited as the result of the 
Hercynian system of movements in the South of England, would 
suggest that the main movements occurred in Permo-Triassic times, 
though it is by no means certain that they were not continued until 
a later period. | 


VIII. Knotts oF LimesToneE IN OTHER AREAS. 


Examination of knoll-shaped masses of limestone in other areas 
yields results similar to those which I have enumerated, and in all 
cases, as already stated, the knoll-shaped masses occur in regions 
which have undergone movements of an orogenic character. Among 
the features which I take as characteristic of knoll-structure are: 
(i) sudden expansion of the limestone in the knoll; (11) irregularity 
of bedding, changes in dip and strike being constantly noticeable, 
and determining the characteristic weathering which results in 
the knoll-form, and not in continuous escarpments ; (iv) crystalline 


ee 


Vol. 55.] THE CRAVEN DISTRICT OF YORKSHIRE. 309 


character of the limestone, which is usually white, light grey, or 
pink, the last-named colour being probably due to subsequent 
staining ; and (v) frequent dolomitization and silicification. I may 
remark that in all the cases that I have examined the knoll- 
structure is developed only in comparatively pure limestone, while 
associated argillaceous limestones, even when found under conditions 
similar to those which furnish knoll-structure, do not seem adapted 
for its development in a state approaching perfection. 

Commencing with an account of knoll-structures developed in 
our own country, I have notes of its occurrence in the Coniston 
Limestone Series of Keisley in Westmoreland, Millom in Cumber- 
land, and in the neighbourhood of Dalton-in-Furness. I have alluded 
to the existence of a white horny limestone lying between the 
ordinary Applethwaite Limestone and the Staurocephalus-limestone 
of the Coniston Limestone Series,’ and suggested that the Keisley 
Limestone, which probably occupied this position (a suggestion 
since confirmed by Mr. F. R. C. Reed) was identical with this 
limestone. This is probably also the case with the white crystalline 
limestones of Dalton-in-Furness and Millom, as the ordinary impure 
ashy Coniston Limestone is seen in its normal condition close to 
these, and it would require the abstraction of a considerable amount 
of insoluble material to convert this limestone into the comparatively 
pure crystalline limestones of those localities. The Keisley Lime- 
stone shows evidence of much disturbance and uneven bedding. 
Prof. Nicholson and I wrote of it elsewhere :—‘ The limestone itself 
shows signs of much disturbance : it contains twisted wisps of shale 
in places, and the occurrence of beds containing numerous Jilenz with 
their convex surfaces uniformly pointed downwards indicates 
inversion.’* It further resembles the knolls of Craven in the 
crystalline character of the rock, the sporadic distribution of fossils, 
and occasional dolomitization. It is surrounded by faults, and 
occurring as it does between hard rhyolitic rocks on one side 
and the hard bands of the upper part of the Stockdale Shale 
Series on the other, it is in a position eminently adapted for 
having the knoll-structure impressed upon it. Mr. F. R. C. Reed,’ 
while partly accepting my views as to the origin of the Keisley 
‘knoll,’ does not appear to consider them sufficient, and puts 
forward a theory of discontinuous distribution to account for the 
fauna, with hints at migrations. If his view be accepted, after 
the migration, and during the occupation of the isolated regions at 
Keisley, Kildare, and elsewhere, either the intervening seas were 
untenanted by organisms, or else they were tenanted by an earlier 
or a later fauna than that of the Keisley Limestone, or a mixture 
of the two. Under the circumstances, it is difficult to see why the 
fauna of Kildare should be so like that of other places. Discon- 
tinuous distribution is a convenient escape from the difficulty, but 


1 Geol. Mag. 1892, p. 100. 
2 Quart. Journ. Geol. Soc. vol. xlvii (1891) p. 507. 
3 Ibid. vol. liii (1897) pp. 100 ez segg. 
24 2 


306 MR. J. E. MARR ON LIMESTONE-KNOLIS IN [ Aug. 1899, 


anyone who has had much experience in the field among limestone- 
rocks knows that ‘ discontinuous distribution’ often means only 
discontinuity in the area from which fossils have been collected. 
I believe it to be so in this case, and the existence of the thin white 
limestone, which has yielded few fossils, but was no doubt entirely 
composed of organisms, and occupies the position of the Keisley 
Limestone elsewhere, must be taken into account. 

Mr. Reed’s views further necessitate a very limited distribution 
for his ‘stations’ of the Keisley Limestone fauna. For the Keisley 
station 2 or 3 miles at most can be given, unless it is supposed to 
have extended in a long linear strip at right angles to the present 
outcrop. Moreover, similar cases of apparent discontinuous dis- 
tribution occur in other areas under identical conditions, that is, 
in each case in areas wherein the rocks have undergone orogenic 
movements. Mr. Reed, it is true, suggests that ‘the fact that 
the limestone in each of these outposts or stations has 
suffered so much mechanical disturbance may, perhaps, be in the 
main attributable to its reef-like nature and mode of occurrence, 
as a local thickening of an elsewhere thin band of rock.’ As a 
result of observation, I should iafer that a thin limestone is much 
more likely to be subjected to such disturbance than one which is 
locally thickened. J have commented upon Mr. Reed’s views at 
some length, because, if correct, they negative the value of the 
Keisley Limestone as bearing upon my opinions regarding knoll- 
structure, for I have maintained elsewhere that the Keisley Lime- 
stone is ‘a block of the neighbouring strata squeezed up and 
displaced.’ This view Mr. Reed curtly dismisses’ as ‘ utterly unten- 
able when we ascertain the unique facies of the fauna and its 
dissimilarity to that of any other British beds.’ Ido not see why it 
is untenable: the view that I have taken accords with observations 
along other parts of the Coniston Limestone outcrop (which I am not 
aware that Mr. Reed has examined in detail); that view is as stated 
above, and I fail to see any difficulty in supposing a deposit to yield 
abundant fossils in one locality, and not in others. It is a matter 
of constant occurrence. 

At Millom the outcrops of the Coniston Limestone show knoll- 
structure, and the dips are very conflicting. At Hillbank there is 
evidence that the beds are thrown into a series of broken overfolds, 
with subsequent formation of hematite along the fault-planes. An 
interesting feature of this section is that, although lithologically 
similar to the Keisley Limestone, the beds are apparently un- 
fossiliferous. 

At High Haulme, near Dalton-in-Furness, there is a remarkable 
disposition of the strata ot one of the members of the Coniston 
Limestone Series. They occur in three bands, separated by inter- 
vening depressions. Each ot these bands is divided by subsidiary 
depressions into knolls, the limestone in each knoll striking 
obliquely to the general trend of the bands. It is possible that the 


Quart. Journ. Geol. Soc. vol. liii (1897) p. 101. 


Vol. 55.] THE CRAVEN DISTRICT OF YORKSHIRE. 357 


intervening depressions are filled with shales, but the sections are 
rather poor. 

The structure of the middle and lowermost Upper Devonian 
Limestones of the Torquay area has frequently been the subject 
of remark. A cursory inspection of them some years ago gave 
evidence of the same kind of features as those which I have 
described as occurring elsewhere in knolls. I have already alluded 
to Mr. Wethered’s remarks on these rocks, and would here quote 
a suggestive passage from Mr. Ussher’s paper on the Devonian 
rocks of South Devon*:—‘A part of the Barton limestone is a 
coral-breccia recemented; and in one nearly vertical fissure or 
fault the fragments also appear rolled. Whether this phenomenon 
is due to surf-talus banked on a mass of coral-growth or not, I 
leave to the judgment of those better qualified to form an opinion.’ 

On the Continent I have seen what I take to be knoll-structure 
ain the Ordovician Leptena-limestones of Dalecarlia, and in the 
Devonian limestones of Koneprus in Bohemia. The Leptena- 
limestone exhibits all the features which I have described as charac- 
teristic of knoll-structure, and it would be tedious to repeat them; 
and the same may be remarked of the limestone of Koneprus. A 
very significant fact is the inclusion in the Leptena-limestone of 
Boda of apparent pebbles of shale, which, however, belong to beds 
newer than the Leptcena-limestone, indicating the occurrence of 
complex earth-movements here. In the case of the Leptena- 
limestone Nathorst has brought forward evidence that it is a special 
condition of a thin unfossiliferous limestone—the Klingkalk,? while 
the thick knoll of Koneprus is represented nearly all the way 
round the Bohemian basin by a thin band of grey or white horny 
limestone. 

I would once more emphasize the fact that all these knoll-shaped 
structures occur in regions where the rocks have been subjected to 
considerable orogenic movements, 


IX. Conciupine REMARKS. 


' I have attempted to show that knoll-structure is produced by 
orogenic movements. In so doing, I have admitted that my exami- 
nation of the only typical ‘ knolls’ (according to Mr. Tiddeman) that i 
have seen did not furnish much direct information in support of my 
views, and I have tried to prove that there is a similarity of struc- 
ture, indicating community of origin, between the typical knolls 
and other knoll-like masses which T have endeavoured to explain as 
due to orogenic movements. 

I must frankly admit that my views are contrary to those of 
well-known writers. The limestones of Keisley, Devon, and 
Dalecarlia, as well as those of Craven, have been elsewhere ascribed 
to processes not differing in a marked degree from those suggested 


} Qaart. Journ. Geol. Soc. vol. xlvi (1890) p . 503. 
2 Geol. Foren. i Stockh, Forhandl. vol. vii (1885) p. 559. 


358 LIMESTONE-KNOLLS IN CRAVEN. [Aug. 1899, 


by Mr. Tiddeman, while the account of ancient coral-reefs given 
by Dupont’ and Mojsisovics* may also be quoted against me. Lest 
I should be charged with presumption, I may add that it is now 
nearly twenty years since the subject first attracted my attention, 
and I have devoted some time to it intermittently ever since. 
Should the main contention of this paper be proved incorrect, I 
venture to hope that in any case there are observations recorded in 
it which may prove to be of interest. 


PLATE XXIV (facing p. 339). 


View of knolls near Scaleber, Settle, reproduced from a photograph taken by 
H. J. Garwood, M.A., F.G.S. 


[For the Discussion on this paper, see p. 361. | 
* Dupont, E., ‘Les Iles coralliennes de Roly et de Philippeville,’ Bull. Mus. 


Roy. Hist. Nat. Belg. vol. i (1882) p. 89. 
* Mojsisovics, E. yon, ‘ Dolomitriffe von Siidtirol u. Venetien, 1879. 


° 


Vol. 55.] LIMESTONE-KNOLLS IN CRAVEN. 359 


22. The Limestons-xnoitis below Skipton and GRassINGTON im 
Craven. By J. R. Daxyns, Esq., M.A. (Communicated by 
the Presipent. Read April 26th, 1899.) 


A BAND of limestone runs from Cracoe (a few miles north of 
Skipton) in a north-easterly direction towards the River Wharfe. 
This band forms an anticlinal; for along its north-western flank the 
limestone is seen to dip north-westward beneath beds of shale, which 
have a similar dip; and on its south-eastern flank the limestone 
dips south-eastward under the shales and grits of Thorpe Fell, the 
top of the rock running from Butter Haw nearly along Thorpe 
Lane towards the northern end of Elbolton. In several places the 
top of the limestone is brecciated, and the overlying Bowland Shale 
contains fragments of limestone. 

Although the general structure of the country is thus sufficiently 
plain, the details of the limestone are not easily made out. This 
rock forms five conspicuous hills, more or less conical, which stand 
up abruptly from the general level of the ground at the foot of the 
gritstone fell. Their names in order, beginning at the south-west 
and going round by north-east to east, are Skelterton, Butter Haw, 
Stebden Hill, Elbolton, and Keal Hill. They are all formed of 
massive limestone. 

The beds on Skelterton have an easterly dip, and owing to rolls the 
top of the limestone runs ina curvilinear fashion to Butter Haw, which 
forms an anticlinal, and thence nearly along Thorpe Lane towards 
the northern end of Elbolton, leaving Stebden Hill apparently as an 
island. On the north side of the last-named hill I found beds 
dipping north-westward at 40°, but no satisfactory dip could be 
ascertained on any other part of the hill. It may be faulted on the 
south side: for the limestone appears to be disturbed at the foot of 
the hill, where I found a north-easterly dip of 53° into the hill, and 
the Lower Millstone Grits are striking at the limestone-hill; but 
the latter appearance would necessarily result if the beds formed 
subsequently to the limestone had been laid-down on a very uneven 
surface. I could see nothing of the solid rocks in the hollow between 
Butter Haw and Stebden Hill; but it is obvious that, unless there is a 
fault between the two hills, the limestone must either turn up again 
on the south-eastern side of the Butter Haw anticlinal or have been 
originally formed in a moundy fashion. 

As to Elbolton, I found it quite impossible to make out how the 
limestone was lying. At the northern foot of the hill and on the 
western flank I obtained dips of 20° to 35°, consistent with the idea 
that the hill is a dome with a quaquaversal dip ; but on the south 
side I measured a dip of 15° into the hill, and over the greater part 
of the hill I could find no dips at all. Thus baffled outside, I tried 
inside ; for the hill is traversed by veins and pipes of galena, and 
entrance into the very heart of the rock may be gained by the mine- 
adits. Nevertheless I met with no more success inside than out: 


360 MR. J. R. DAKYNS ON THE LIMESTONE-KNOLLS [Aug. 1899, 


nearly everywhere alike the limestone is an amorphous 
mass without a trace of bedding. 

On Kea] Hill I was equally unsuccessful: at the northern end J 
measured at the foot of the hill dips varying from 10° to 30°, mostly 
towards the south-south-west, and at the southern end conflicting 
dips of 45° north-eastward into the hill and of 35° south-south- 
westward. The last-mentioned dip would take the limestone 
naturally below the shale, which is to be seen on that side dipping 
southward and extends all along Stanton Beck, the boundary of the 
hill on the east side. On the main mass of the hill, however, I 
found no measurable dips at all. 


I therefore considered that, owing to the amorphous character of 
the limestone, it was quite uncertain whether the abrupt and detached 
character of these remarkable hills, Keal Hill, Elbolton, and Stebden 
Hill, was due to faulting or to a quaquaversal structure: but when 
subsequently Mr. Tiddeman propounded his view that the limestone 
had been originally formed in the shape of mounds or knolls, and 
pointed out that the overlying shale contained fragments of lime- 
stone after the same fashion as it does in the Clitheroe and Slaidburn 
country, I readily accepted his idea as offering a simple and satis- 
factory explanation of the evidence seen on the ground. 

I have not examined the limestone-knolls about Thorpe Fell 
since the time when I was engaged there in my official work 
for the Geological Survey; but I have seen south of Grimwith 
Reservoir (east of the River Wharfe), on the same horizon as 
near Thorpe Fell, shale similarly containing fragments of limestone. 
About these there can be no doubt that they fell into the sea, 
and were embedded in the shale while it was being deposited ; 
for beyond having a northerly dip, conformable to the limestone 
below and the Millstone Grit above, the shale is quite undisturbed, 
and thus there can be no question here of faulting or crush- 
brecciation. The idea, then, that the limestone-fragments in shale 
near Thorpe Fell had fallen into the water from some reef or 
shell-mound, and had thus become embedded in shale which was 
being deposited round and over the mounds, seems quite reasonable. 
This idea, too, affords a simple explanation of the geological features 
of the country, and relieves us of the necessity of supposing either 
faults or a quaquaversal doming-up, for which there is little or no 
evidence. 

We have, moreover, independent evidence that the surface of the 
limestone underneath the overlying shales and grits is uneven. 
On Simonseat, a Millstone Grit fell on the east side of the Wharfe, 
there are some swallow-holes, which show that limestone is 
present at no great distance below the surface : but below Thorpe Fell 
is a thickness of at least 450 feet of shale overlying the limestone, 
and there may be in places much more; and nearly 1200 feet 
of sandstones and shales occurs between the base of the Kinder 
Scout Grit and the top of the limestone. It does not seem possible 


Se 


Vol.55.] | BELOW SKIPTON AND GRASSINGION IN CRAVEN. 361 


that swallow-holes should be formed into limestone through any- 
thing like 400 feet of shale; it is more than probable that under 
Simonseat the limestone is much nearer the Millstone Grit than it 
is in other places: that is, the limestone-surface is very uneven. 

Furthermore, the amorphous and unbedded character of the lime- 
stone is itself an argument in favour of the view that the rock was 
originally formed as a group of mounds, whether as reefs or as heaps 
of shells that were not strewn out by wave and currents; for such 
mounds would have no bedding. Supposing that the limestone 
had been originally a bedded rock, how has it lost its bedding? 
Along a line of fault a rock is often brecciated, and perhaps may be in 
extreme cases crushed to such a degree that the bedding is destroyed 
for some little width along the plane of movement; but such cases 
must be very rare in Craven, for I have never seen an instance along 
any of the numerous faults by which the country is intersected. 

We have, moreover, positive evidence that bedding is not destroyed 
by the rocks being squeezed up into folds. ‘The whole country south 
of the North Craven Fault as far as the River Aire has been pressed 
into a number of folds, whose axes are directed approximately 
east and west, and along some of these the limestone has been 
excessively contorted; but its bedding has not been 
destroyed. So far is pressure from destroying bedding that it is 
bedding which proves pressure. From the contortions in bedding, 
at Draughton and elsewhere, we learn that the limestone has been 
slowly squeezed under great pressure: this was exemplified some 
years ago by the experiments of Prof. Miall, undertaken with the 
express object of explaining how such a rock as limestone could be 
folded in such a fashion as may be seen at Draughton. 

Therefore I do not believe it possible for the limestone to have had 
its bedding crushed out through the whole extent of such a hill 
as Elbolton, which has a diameter at its base of 900 yards from 
north to south and of 1000 yards from east to west. When we find 
so great a width of amorphous limestone, the obvious inference is 
that it never had any bedding. 


Discussion (ON THE TWO FOREGOING PaPERs). 


Mr. Tippeman congratulated Mr. Marr on the interesting facts 
and observations brought forward, but he regretted that he could 
only follow him to a certain extent in his conclusions. He quite 
admitted that there was much crushing and folding in the district, 
but chiefly in that about Draughton taken by Mr. Marr to illustrate 
his remarks. There was, however, no appearance of reef-knoll 
structure in that more complicated area, and in the parts where 
reef-knolls abounded the excessive faulting was absent. Perfect 
fossils abounded in the reef-knolls, as the collections made by 
Mr. James Eccles (now in the Blackburn Museum) and Mr. Garwood 
showed. The question was really only part of a much larger subject 


362 LIMESTONE-KNOLLS IN CRAVEN. [ Aug. 1899, 


relating to the physical conditions of sea and land existing when the 
beds were formed. He (the speaker) had suggested that the Craven 
Fault was in action while the Carboniferous rocks were being 
formed.. He had had the good luck to find a remnant of the 
old reef-beach on the upthrow side of the fault above Dibbles 
Bridge, and this he exhibited. He was glad to note that Mr. Dakyns 
supported his views, and was very grateful to Mr. Marr for having 
brought forward the subject. 

Dr. Wueetton Hinp remarked that he could not but be struck 
with the extreme ingenuity of Mr. Marr’s views, but with many of 
his facts he could not agree. The paper was delusive, most of the 
evidence being taken from another district where knolls were 
distinctly absent. Knolls were characteristic of the upper beds of 
the Carboniferous Limestone in Derbyshire, Staffordshire, and else- 
where. They formed the great fossil deposits of the Carboniferous 
Limestone, and he (the speaker) had worked them for several years. 
Bedding was always obscure, fossils were sometimes rolled, and 
the thickness of the knolls varied from a few feet to many yards. 
They were not always dome-shaped, and occasionally there was a 
thin bed. Still, breccia with limestone-pebbles was always asso- 
ciated with these phenomena. He could not accept Mr. Marr’s 
view that the Craven Faults had any bearing on the difference in 
type between the Limestone south of the faults and the Yoredale 
Series to the north. He disagreed with the correlation given in 
Mr. Marr’s paper. The Pendleside Limestone was a peculiar hard 
black limestone, thinly-bedded, breaking with a conchoidal fracture, 
and yielding a fauna similar to that of the Gannister Series 
of the Coal Measures, and it did not contain any of the fossils of 
the Mountain Limestone. It was quite distinct in lithological 
character and in its paleontology from the knoll-limestone and: 
from any of the beds of Yoredale limestone. The term ‘ Upper 
Scar Limestone’ was unfortunate, and was used for different beds 
in different areas. He asked which was the particular bed that 
Mr. Marr meant. Simple measurements were opposed to this 
correlation also, which had not a single fact to rely upon—neithe 
paleontological, lithological, nor stratigraphical. 

Mr. Garwoop corroborated Mr. Marr’s testimony regarding the 
evidences of crush-movement in the district described, and mentioned 
that he had noticed great disturbance between the Elbolton reef and 
the shales immediately overlying it, as evidenced by crinoid-stems, 
contorted and drawn out, among the breccia-fragments which here 
form the junction. He pointed out that the wonderful state of 
preservation of the fossils in the reefs cited by Mr. Tiddeman might 
be due to absence of pressure in the axes of the anticlinals. The 
high dip of the reefs in places was very conspicuous, and he had 
found, from extensive collecting in the reefs, that the dip generally 
was clearer than supposed by some speakers. 

Mr. Lamptvex thought that the structures described by Mr. Marr 
were undoubtedly of a character similar to that of the limestone- 


Vol. 55.] LIMESTONE-KNOLLS IN CRAVEN. 363: 


knolls so magnificently exposed on the foreshore of Poolvash Bay in 
the Isle of Man. His impression had been that these knolls were 
original structures; and after careful re-examination he still failed 
to see how they could be accounted for otherwise, though he would 
admit that there was evidence of lateral movement in the rocks in 
the vicinity. That columnar masses of limestone might accumulate 
among shales was proved by the ‘Tepee Buttes’ of Colorado. If an 
area in which lenticular masses occurred were subsequently disturbed, 
he thought that all the phenomena described by Mr. Marr might be 
produced. He regretted that the relation of the paleontology of the 
knolls to that of the surrounding beds had not been discussed, as it 
seemed of vital importance. 

Prof. Sortas recognized the value of the observations, and the 
ingenuity of the explanation so clearly set forth by Mr. Marr; he 
thought, however, that insufficient allowance was made for the 
general tendency of corals and calcareous alge to assume reef-like 
forms. Some steps appeared to be missing in the argument that 
erystalline limestone, distinguished by the exceptionally perfect 
state of preservation of its included fossils, had assumed the crys- 
talline state owing to relief of pressure. If this meant that a dimi- 
nution had followed an excess of pressure, the crystalline state 
might be accounted for, but not the preservation of the fossils: if, 
on the contrary, it meant that the knolls had been sheltered from 
the excessive action of pressure, the preservation of the fossils was 
explained, but not the crystalline state. It seemed more probable 
that originally reef-like growths had consolidated before movement 
took place; if these, with their associated conglomerates, were 
buried in sediment, and then subjected to rock-folding and flow, 
just such phenomena as had been described would naturally 
result. 

Mr. Srranan regretted that no one present had seen both the 
isle of Man and the Yorkshire sections. ‘The structures seemed, 
however, to be similar; and those in the Manx Carboniferous Lime- 
stone were certainly, in his opinion, of contemporaneous age, and 
not due to subsequent movement. It was noticeable that the knoll- 
reefs were of local occurrence, and did not exist in many places 
where there was evidence of much thrusting, as, for example, along 
the Dent Fault. The conglomerates exhibited by Mr. Marr did not 
resemble fault-rock, but contained what seemed to be true rounded 
pebbles or nodules, nor did it appear possible that lmestone-bands 
could have been so folded as to completely enveldp a nucleus, as was 
the case with many of these nodules. Conglomeratic bands of this 
nature, moreover, were not uncommon in the Carboniferous Lime- 
stone in other districts, where there was no suggestion of earth- 
movements. At the same time, Mr. Marr had produced abundant 
evidence of the effects of earth-movement in the area which he had 
described, and it seemed likely that the original structures in the 
limestone had been somewhat modified thereby. 

The Prusipent, Dr. Sorsy, and Prof. Warts also spoke. 


364 LIMESTONE-KNOLLS IN CRAVEN. [Aug. 1899, 


Mr. Marr, in reply, admitted that he had overlooked the nodular 
origin of the pebble-like forms in the rock from the stream flowing 
into Winterburn Reservoir. If that origin were established, it 
would not throw light on either explanation of the breccias. He 
protested against the statement that he had only described proofs 
of folding in a district at some distance from the knolls. He had 
taken Draughton Quarry because it was a well-known section, but 
similar proofs of disturbance might be found throughout the area. 
In reply to Dr. Wheelton Hind, he observed that several of the 
statements which that speaker had made were, he believed, equally 
opposed to the views of Mr. Tiddeman and to the views expressed 
in his paper. He agreed that paleontological evidence would be 
most satisfactory, and had tried to obtain it, but, meeting with 
difficulties, had used lithological characters as being to some extent 
valuable. Dr. Hind spoke of the similarity of ‘the breccia’ in the 
Craven district and in Derbyshire, but he (Mr. Marr) would point 
out that there were several breccias at different horizons in the 
Craven area. : 


Wel.'55.] CARBONIFEROUS LAMELLIBRANCHIATA. 365 


23. On Turee New Species of LaMELLIBRANCHIATA from the 
CaRBONIFEROUS Rocks of Great Britain. By WuHeEEtton Hinp, 
M.D., B.S., F.R.C.S., F.G.S8. (Read April 26th, 1899.) 


[Piate XXV.] 


I. On a new species of Anthracomya, from the Upper Coal 
Measures of North Staffordshire. 


Introduction.—In my monograph on Carbonicola, Anthracomya, 
and Naiadites* I pointed out that only one lamellibranch was then 
known to occur in the Upper Coal Measures of North Staffordshire, 
and indeed of Great Britain. The comparative sections illustrating 
the distribution of the Lamellibranchiata in the various coalfields 
showed that in a large number of them the highest known lamelli- 
branch was Anthracomya Phillips, and that this species might well 
be considered characteristic of acertain zone. Since the date of that 
publication I have been able to accumulate material from a series 
of beds in the North Staffordshire and Lancashire coaltields much 
higher than the A. Phillipsiz-zone, which contains a hitherto unde- 
scribed fossil shell, evidently referable to the genus Anthracomya. 
This species appears to characterize also a certain somewhat narrow 
zone of calcareous shales and freshwater limestones which occur 
towards the top of the Coal Measures in these localities. The shells 
from Fallowfield were collected by Mr. Reeder. They are free from 
the matrix, and, although often fragmentary, afford distinct details of 
the hinge. I am not sure whether there are not at least two distinct 
species from the Fallowfield beds, but hesitate to erect a new species 
on mere fragments. 


ANTHRACOMYA CALCIFERA, sp. nov. (Pl. XXYV, figs. 14-20.) 


Specific Description.—Shell small transversely, modioliform, 
very inequilateral, gibbose, expanded and flattened posteriorly, | 
oblique. The anterior end is very short, and narrower than the rest 
of the shell, and its border is elliptically curved. The inferior border 
is produced downward and backward, and is almost straight, sub- 
parallel with the superior border. The posterior border is com- 
paratively lengthened obliquely, truncate from above downward 
and backward, and is straight for the greater part of its extent, 
but joins the inferior border at a somewhat rounded angle. 

The hinge-line is straight, much shorter than the inferior border, 
and the posterior superior angle is well marked and obtuse. The 
umbones are small, pointed, incurved, and contiguous, placed in the 
anterior quarter of the shell. 

Passing downward and backward from the umbo towards the 
posterior inferior angle is a well-marked, bluntly rounded fold, in 
front of which the valve is obliquely compressed, and posterior to 


1 Palzont. Soe, pt. ii, vol. xlix (1895) p. 156. 


366 DR. WHEELTON HIND ON BRITISH [Aug. 1899, 


this fold the valve is rapidly compressed and expanded to form the 
dorsal slope. 

Interior.—Hinge edentulous. Muscle-scars normal.  Pallial 
line entire, remote from the margin. 

Exterior.—tThe shell appears to be almost smooth, but under 
the microscope faint concentric lines of growth are to be observed. 
Periostracum wrinkled. Ligament external, small, lodged in a 
narrow groove, 

Dimensions.—Antero-posteriorly, 6 mm.; dorso-ventrally, 
3 mm.; elevation of valve, 1 mm. 

Localities.—A bed of freshwater limestone at Highfield marl- 
pit, Etruria, and excavation for telegraph-posts, roadside, Bradwell ; 
marl-pit east of Cocknage Hill; railway-cutting, Florence Colliery ; 
road-cutting, from Trentham to Whitmore, close to Butterton New 
Farm; Neweastle-under-Lyme railway-cutting; Etruria, road- 
cutting ; quarries near Longport Station ; marl-pit, Richmond Hill, 
Stoke-on-Trent; Upper Coal Measures, Slade Lane, Fallowfield, 
Manchester coalfield. 

- Observations.—This species is much more elongate, less 
oblique, and attains a much smaller size than Anthracomya Phillipsit. 
The species which it most nearly resembles is A. minima, Ludwig, 
which is flatter, more triangular, and has a much shorter hinge-line. 

I am of opinion that A. calcifera is of distinct value as indicating 
a special zone, and it appears to be the only molluscan form present 
in that zone. It has not yet been discovered in beds which contain 
A, Phillipsii. A. calcifera is present in very large numbers at 
certain horizons in its zone of occurrence, but it is very sparsely 
distributed through the rest of the rock of its zone. 

The zone of A. Phillipsti is much more extensive, and altogether 
below that of A. caleifera. The zone of A. calcifera occurs 300 feet 
below the Penkhull Sandstone, mapped by the officers of the 
Geological Survey as Permian, and estimated to be about 900 feet 
above the Bassey Mine Ironstone, which itself is filled with crushed 
specimens of A. Phillips. The Penkhull Sandstone is underlain 
by a series of grey sandstones and grey marls with the zone of 
A. calcifera at their base: these were included by the officers of the 
Geological Survey in the Upper Coal Measures. They are under- 
lain by a series of clays and marls, worked for brick- and tile- 
manufacture. 

It is very difficult to separate A. calcifera from the hard matrix 
of the limestone, and unless this be done its characters are 
often hidden. With its posterior angle hidden, the shell may 
be easily mistaken for a species of some other genus, especially 
Carbonicola. In specimens from the limestones, also, little evidence 
is shown of the wrinkled periostracum, so characteristic of the 
genus, but when preserved in a more shaly matrix undoubted 
evidence of this condition obtains. Occasionally, too, the shells 
are crushed and flattened, and then assume a shape very different 
from that which really belongs to them, becoming much more 
triangular; while the posterior end, on account of its natural 
convexity, appears much expanded from above downward. 


—— — gaan 


Vol. 55.] CARBONIFEROUS LAMELLIBRANCHIATA, 367 


II. Carbonicola Vinti (Kirkby). (Pl. XXV, figs. 5-13.) 
(2) Ancylus Vinti, Kirkby, Trans. Tyneside Nat. Field Club, vol. vi (1864) p. 220. 


Specific Characters.—Shell very small, inequilateral, ovate, 
compressed. The anterior end is broad, and its border is regularly 
rounded. The inferior border is regularly but gently convex. The 
posterior border is narrowed by the approximation of the upper 
and lower margins, obliquely truncate from above downward 
and backward, making a well-marked obtuse angle with the 
hinge-line above and an acute angle with the inferior margin below. 
The hinge-line is arched, extended, and depressed posteriorly. The 
umbones are small, tumid, slightly elevated, and situated in the 
anterior fourth of the shell. 

The valves are regularly and gently convex for the anterior two- 
thirds, but gradually compressed in the posterior third. 

Interior.—The muscle-scars appear to be normal. The hinge 
has not yet been isolated. 

Exterior.—The surface is smooth and glistening, covered with 
fine concentric lines and folds. Periostracum much wrinkled. 
Shell thin. 

Dimensions. — Antero- posteriorly, 5 mm.; dorso-ventrally, 
3 mm.. 

Localities.—In a calcareous bed some yards above the Bassey 
Mine Ironstone, in an old marl-hole near Chatterley Station; in cal- 
careous bands about 10 yards above the Bassey Mine Ironstone, the 
Hamil, Burslem, Upper Coal Measures, North Staffordshire ; in a bed 
of ironstone in the northern bank of the Wear, opposite Claxheugh, 
Upper Coal Measures, Durham. 

Observations.—A very full account of the history of the 
discovery of this fossil is given by Mr. J. W. Kirkby (op. supra cit.), 
who was disposed to admit the lamellibranchiate character of this 
little fossil, which was considered by some high authorities to be 
a gasteropod (Ancylus), by others to be a brachiopod allied to 
Diseina, and was thought by yet others to be a crustacean. 

I have referred my specimens to Mr. Kirkby, Prof. T. Rupert Jones, 
and Dr. G. J. Hinde, with the following result :—The latter two 
gentlemen consider that the shell is a lamellibranch, and Mr. Kirkby 
writes that it is identical with his Ancylus Vinti. The specimens 
that I have of ‘Ancylus Vinti’ from the Durham beds, kindly 
sent by Mr. Kirkby, seem to me to be simply the closely compressed 
remains of the periostracum of a large number of shells, a circum- 
stance which probably accounts for the difficulty in accurately 
determining the fossil. 

Fortunately the North Staffordshire specimens are much better 
preserved, and, though generaily somewhat crushed, show the 
general outline and character of the shell, and are therefore more 
easily referred to their real family and genus. After discussing 
the question of the true affinity of this shell at length, Mr. Kirkby 
finishes by saying :—‘ For the present, therefore, it will be as well, 
perhaps, to retain as a provisional name Prof. Phillips’s term of 


368 DR. WHEELTON HIND ON BRITISH [Aug. 1899, 


Ancylus. This I propose chiefly to get rid of the evil of having an 
unnamed fossil .... and not because I am of the opinion that 
it really belongs to Ancylus. For, whether it be an entomostracan 
or a mollusc, the evidence certainly would appear to go towards 
proving that it had a bivalvular rather than an univalvular 
carapace.’ 

Carbonicola Vinti would appear to be the last representative of 
this well-developed and frequently recurring Carboniferous fresh- 
water genus, and to occur at a higher horizon than any other 
species of the genus. As Mr. Kirkby points out is the case in the 
Durham beds, this fossil is associated in North Staffordshire also 
with a non-marine fauna. He estimates that Carbonicola Viuti 
occurs at an horizon not much over 50 or 60 feet from the top 
of the Coal Measures or the base of the Lower Red Sandstone, but in 
North Staffordshire there is a thickness of several hundred feet of 
red and purple beds of the Upper Coal Measures above the horizon 
of this fossil, C. Vinti occurring in this coalfield about the middle of 
the zone of Anthracomya Phillips. 


III. On a new species of Cienodonta from Penton Linns 
(Dumfriesshire). 


Introduction.—In pt. ii of my monograph of the British 
Carboniferous Lamellibranchiata* I described a single species, 
Otenodonta sinuosa (de Ryckholt), as being the only known repre- 
-sentative of that genus in the Carboniferous rocks of Great Britain. 
After the work was in print I obtained several specimens of another 
species which should undoubtedly be referred to this genus, as its 
hinge-plate possesses no cartilage-cavity between the anterior and 
posterior rows of hinge-teeth. ‘These specimens occurred in a richly 
fossiliferous, marine, blue shale, overlain by a massive limestone 
forming a small gorge, through which the River Liddell rushes, 
Another thick bed of limestone also occurs below it. The bed of 
shale is on the Scottish side of the stream and forms a small scar, 
which is evidently covered by a kind of backwater when the river 
ishigh. This shale is slightly inclined ; its surface is covered with 
fossils and contains a very rich fauna, one which ‘indicates un- 
doubtedly an estuarine condition. This fauna corresponds to a 
large extent with that of the shales which occur among the lime- 
stones of the Lower Limestone Series of the West of Scotland. The 
following lamellibranchs may be found in this bed :—Nucula gibbosa, 
Phill.; NW. levistriata, Portlock; NW. wndulata, Phill.; Nuculana 
attenuata (Phill.); Ctenodonta; Protoschizodus axwiformis (Port- 
lock); Pinna flabelliformis, Martin ; and Hdmondia, sp. nov., to be 
described and figured in pt. iv of my monograph. 

The exact place in the series is doubtful, but the beds are re- 
ferred to the horizon of the Hurlet Limestone of Scotland by the 
officers of the Geological Survey. It is probable that these lime- 
stones are identical with those exposed in quarries at Harelaw Hill, 


1 Palzont. Soc. vol. lii (1898) p. 210. 


Vol. 55.] CARBONIFEROUS LAMELLIBRANCHIATA. 369 


1 mile north-west of this locality, and at Peter’s Crook Quarry, 
about 4 mile to the east on the English side, in both of which 
are seen two thick limestones separated by a richly fossiliferous 
marine shale which has a fauna largely identical with that con- 
tained in the shale in the river-bank. This bed is rich in gaste- 
ropoda, the genera Murchisonia, Macrocheilus, Pleurotomaria, Loxo- 
nema, and Huomphalus being represented in it. Bellerophon Urea 
and B. decussata also occur, together with Orthoceras, Fenestella, 
brachiopods, crinoids, and Archeocidaris. Productus giganteus 
occurs in the limestones, and therefore affords strong evidence 
that the identification of the horizon with that of the Hurlet 
Limestone is correct. 


CTENODONTA PENTONENSIS, sp. nov. (Pl. XXV, figs. 1-3, 3a & 4.) 


Specific Characters.—Shell transversely and triangularly 
ovate-acute, moderately gibbose, very inequilateral. 

The anterior portion of the shell is about one-third of the valve, 
and is moderately swollen, its border being elliptically curved. The 
inferior border is extended, and is very convex. The posterior border 
is exceedingly small and bluntly pointed, much narrowed by the 
approximation of the upper and lower borders. The hinge-line is 
arched, especially in front, but becomes straight, extended, and 
depressed posteriorly. 

The umbones are moderately swollen, incurved, contiguous, 
elevated, forming the highest point of the shell, and excavated in 
front, but there is no real lunule. Above the hinge is a very 
narrow elongate groove, posterior to the umbo, for the insertion of 
the external ligament. 

The valve is regularly convex from above downward and before 
backward, and most specimens show that an angular ridge parallel 
to, but at a higher level than, the hinge-line passes from the 
umbones backward to the posterior end, indicating a bending of 
the valve on itself. 

Interior.—The muscle-secars are not exposed in any of the 
specimens yet obtained. The hinge-plate consists of two rows of 
small triangular teeth which meet at an obtuse angle beneath the 
umbo. The anterior set are fewer and larger than the posterior, 
about six in number, the teeth becoming smaller from before back- 
ward. The posterior row contains about eighteen to twenty teeth, 
which increase in size from before backward. 

Exterior.—The surface is covered with well-marked concentric 
lines of growth, one of which occasionally becomes much accentu- 
ated. Shell of moderate thickness. 

Dimensions.—Antero-posteriorly, 30 mm.; dorso-ventrally, 
17 mm.; elevation of valve, 7 mm. 

Locality.—A bed of marine shale below the highest limestone, 
Penton Linns (Dumfriesshire). 

Observations.—Ctenodonta pentonensis differs widely from Ct. 
sinuosa (de Ryckholt), and the two species are not likely to be 


Q.J.G.8. No. 219. 2B 


370 DR. WHEELTON HIND ON BRITISH [Aug. 1899, 


mistaken one for the other. The figure of Ct. Halli’ has a much 
greater resemblance, and, indeed, it is possible that the species may 
be identical, but in the absence of any specimens of the Spanish shell 
I have hesitated to refer the Penton shells to that species. They 
seem to me to be more transverse, more pointed posteriorly, narrower 
from above downward, and neither in the figure nor in the 
description of Barrois’s shell is any mention made of the angular 
ridge parallel to the hinge-line which is present in Ct. pentonensis. 
The dimensions of Ct. Halli, Barrois, are here given for com- 
parison :—Antero-posteriorly, 32 mm.; dorso-ventrally, 19 mm. 


EXPLANATION OF PLATE XXV. 


Fig. 1. Ctenodonta pentonensis, Left valve. Penton Linns; p. 369. Nat. 
size. 


2. ; s Left valve, full-grown size; same locality. 
Nat. size. 

3. 9 ot Right valve, medium-sized specimen ; same 

locality. Nat. size. 

Siig cs 55 Fig. 3 viewed from above, showing the lunule 

and angular dorsal edge. Nat. size. 

4, re i The hinge of a left valve, X 2; same locality. 

5. Carbonicola Vinti, A left valve, x 3, from Chatterley ; p. 367. 

6. + 5 A left valve, <3, crushed, giving rise to an appear- 
ance resembling that of Déscina or Ancylus ; same 
locality. 

is as , A left valve, x3, somewhat crushed, with perfect 
contour; same locality. 

8. - - A slab covered by the periostraca of the shells, x3, 
from Claxheugh, County Durham. 

=. > - Portion of a right valve, x3; same locality. 

10. 2 3 The impression of a right valve, x3; same locality. 


VP a as An uncrushed right valve, x3; same locality. 

Figs. 12 & 13. Carbonicola Vinti. Small specimens from the Hamil marl-pit, 
Burslem; p. 367. 

Fig. 14, Anthracomya calcifera. <A right valve, X3, from roadside, Bradwell, 
in limestone; p. 365. 

Figs. 15 & 19. Anthracomya caleifera. The casts of left valves, X3, from the 
same locality. i" 

Fig. 16. Anthracomya calcifera. A right valve, X 3, from the same locality. 

Figs. 17 & 18. Anthracomya calcifera. A left and right valve, x3, showing 
the hinge-plate and interior, from Slade Lane, Fallowfield, near Man- 
chester. 

Fig. 20. Anthracomya calcifera. 'The left valve of a medium-sized specimen, 
<3, from Bradwell. 


[In the above plate the outlines of figs. 5-20 show the actual size of the 
specimens. With the exception of those reproduced in figs. 15, 17, 18, & 19, 
the specimens are all in my collection. The specimens figured as 15 & 19 are 
in the possession of Mr. Walcot Gibson, F.G.S., and those figured as 17 & 18 
belong to Mr. C. Reeder of Manchester. ] 


1 Barrois, ‘ Recherches sur les Terrains anciens des Asturies & de la Galice,’ 


Mém. Soc. Géol. Nord, vol. ii (1882) No. 1, p. 539 & pl. xvii, fig. 3. 


Quart.Journ. Geol. Soc.Vol.LV.P]. XXV. 


J.Green del.et hth. Maintern Bros .imp. 
AN TE RAG ONY AS CARB ONT OLA. 
6 GTENODONTA’ 


Vol. 55.] CARBONIFEROUS LAMELLIBRANCHIATA, 371 


Discussion. 


The PresipEnt said that he had been asked by Mr. W. Gisson 
who was unable to be present) to state his opinion as follows :— 

He (Mr. Grsson) was very pleased to find that the Author had 
discovered a distinctive fossil, other than fragmentary fish-remains, 
or smooth-valved entomostraca, in the great thickness of Upper 
Coal-Measure strata of North Staffordshire. The occurrence and, 
so far as yet known, the restriction of Anthracomya calcifera 
to the limestone at the base of the grey measures conformably 
underlying the Red Series (Permian of the Geological Survey) is 
an important fact, as bearing upon the age of the Red rocks. The 
correct relegation of the curious little shell found at Burslem and 
elsewhere in the Coal Measures of North Staffordshire to Car- 
bonicola Vinti removes all doubt concerning a very curious fossil. 
The exact value of the zone of C. Vinti has yet to be determined. 
He wished to congratulate the Author on his careful working 
out of the material. 

Mr. Garwovup also spoke. 


232 


372 MR. CLOUGH AND DR. POLLARD ON sPINEL {[Aug. 1899, 


24, On Spinet and Forstrerite from the Guenrte Limestone 
(InvERNEsS-SHIRE). By C. T. Croven, Esq., M.A., F.G.S., and’ 
W. Porzarp, M.A., Ph.D., F.G.S8. (Read April 12th, 1899.) 


[Communicated by permission of the Director-General of 
H.M. Geological Survey.] 


THE primary object of this communication is to describe the occur-. 
rence of two minerals—forsterite and true spinel—which are found 
in close association in a limestone in Glenelg (Inverness-shire), but 
which do not appear to have been recorded hitherto in Scotland. 
Before tabulating the analyses, however, it may be well to mention 
what has been previously written about the limestone, and to- 
describe to some extent its geological position and chief characters. 
The exposure from which the minerals were obtained is on the 
southern side of the Big Glen, or Glenmore, of Glenelg, and it lies 
at a distance of rather more than % mile east of the top of 
Sgiath Bheinn (1-inch map 71, Inverness-shire 6-inch map 47). 
The limestone-band to which the exposure belongs can be traced, 
without any considerable interruption by faulting, for nearly a mile. 
Its general direction is slightly east of north, and the width of 
outcrop varies from a few yards up to 30 or 40. ‘This lime- 
stone is one of a group of limestones which have long been known, 
and are noted for the variety of minerals that they contain. 
Macculloch, in his description of Tiree,’ states that ‘ sahlite,. 
accompanied by tremolite and forming large nodules in Primary 
limestone,’ occurs in Tiree, Harris, and Glenelg, and that coccolite 
and mica, in small crystals of a talcose aspect, are found in the 


limestone in Tiree and Glenelg. In his ‘New Geological Map of 


Scotland,’ bearing the date of 1832, the same author showed an 
outcrop of limestone on the northern side of the Big Glen of 
Glenelg. 

Murchison also speaks of the same limestone-group in his account 
of the ‘ Succession of the Older Rocks in the Northernmost Counties 
of Scotland.’? He says (p. 388), ‘ On the south side of Loch Duich ... 
some of the calcareous bands of highly crystalline limestone are 
white, whilst others are chloritic and greenish and much resemble- 
the Connemara marble of Ireland,—such bands being finely inter 
calated either in micaceous flagstones, in parts calcareous, or in finely 
laminated slaty flagstones, which pass into a rock which must be 
called gneiss.’ In pl. xii, he publishes his ‘ First Sketch of a New 
Geological Map of the North of Scotland,’ and he shows a limestone- 
band on each side of Loch Duich. 

It is, however, to the late Prof. Heddle that we owe most of our~ 
knowledge of this limestone. In some of his ‘Chapters on the- 


1 ‘Western Is. of Scotland,’ vol. i (1819) pp. 53-56. 
? Quart. Journ. Geol. Soc. vol. xv (1859) p. 353. 


a <a te ae ee aS eee 


‘Vol. 55.] AND FORSTERITE FROM THE GLENELG LIMESTONE. 373 


Mineralogy of Scotland,’* he traces the course of limestone ex- 
tending from Totaig, at the foot of Loch Duich, across the Big Glen 
and the Little Glen of Glenelg, to the lower slopes of Beinn a’ 
Chapuill, and he gives descriptions and analyses of many of the 
minerals which he observed in the limestone. Among the minerals 
described are the following :—Malacolite (with two analyses), 
sahlite (with analyses), coccolite (with analysis), and totaigite (with 
two analyses). He speaks also of the occurrence in the limestone of 
other minerals, among which are serpentine (of yellow, green, or 
blue-black tints), a mica resembling the phlogopite of the granular 
limestone of the Vosges, talc, tremolite, and amianthus. In rocks 
either in or close to the limestone, he describes, in addition, 
necronite (with analysis), balvraidite (with two analyses), and 
a pale brown biotite (with analysis). Prof. Heddle noticed that 
some of the serpentine had been formed by the alteration of 
an augitic mineral. He does not, so far as we can ascertain, mention 
the occurrence in these limestones of any mineral of the olivine- 
group, though he states that the totaigite—a serpentinous pseudo- 
morph of rather doubtful character—was first considered by him 
‘to be either chondrodite or danburite.? 

Mr. Alexander Ross * has described some of the minerals in the 
limestone of Loch Duich and Glenelg. He speaks especially of the 
asbestos-veins and serpentine-pieces, and appears to consider that 
these pieces have been formed by the alteration of pyroxenes. He 
describes also the position of the limestone as lying on the east of 
the great line of earth-movement extending from Eriboll to Strome 
Ferry. 

We are not aware that either forsterite or true spinel (MgO, 
Al,O,) has hitherto been recorded in Scotland. Macculloch * 


1 Trans. Roy. Soc. Edin. vol. xxviii (1878) pp. 197 & 453, and vol. xxix 
(1879) p. 1. 

2 The following are the two analyses made by Prof. Heddle of totaigite: 
41) of a pale fawn variety, and (2) of a biue-black variety, which weathers with 
a soft, serpentinous, ochre-yellow surface :— 


(1) (2) 

SO) [SHITE Aanaaaaper nace See nta 37°221 36°193 
EO AMT 0) ono San aidsns "757 ‘264 
Fe,O, Ferric oxide ............ *286 
FeO Ferrous oxide............ 1-045 2'958 
MnO Manganous oxide ...... *230 *454 
WAOe imi 24 ccaae taaeae esate 5:243 3°272 
NicO Magnesia: .s-cc0s0s4-nace 44°973 45°570 
HCO Potash | .scdussevansescvae ‘252 
INA. OF Sodas 2... .ncrosnessmovcee “424 
EO! “Waters. .cacccesecsrere 10°643 10°200 

100°112 99:973* 


* This analysis is reprinted as it appears in Prof. Heddle’s description, but 
there must be some mistake in it. The figures of the different constituents add 
up to 99°873. 

8 * Asbestos near Loch Duich,’.Trans. Inverness Sci. Soc. & Field Club 
vol. iv, p. 49. 

4 ¢ Western Is. of Scotland,’ vol. i (1819) p. 56. 


374 MR. CLOUGH AND DR. POLLARD ON SPINEL [ Aug. 1899, 


mentions that corundum is supposed to have been formerly found 
in Tiree, but he says that no specimens of the corundum have been 
produced, and he evidently doubts whether the supposition is correct. 
Prof. Heddle’ has described a blue sapphire, about =, inch in 
diameter ; this he found embedded in a red andalusite, which rarely 
occurs in quartzose veins, in the schist of Clashmaree Hill, in 
Glen Clova (Inverness-shire), 


The geological survey of the Glenelg district was commenced in 
the summer of 1897, and a short account of the work accomplished 
in that year has already been published.” Much has still to be 
done before the survey of the district is completed, and our remarks 
will only lightly touch some of the interesting problems which the 
district presents to the geologist for solution. 

There are in some places three or four different bands of lime- 
stone .and one of these bands, a short distance east of Beinn Fhada 
Ross-shire 6-inch maps 123 & 127), is as much as 150 yards wide. 
The rocks of the district are, however, greatly folded, generally into: 
isoclinal folds with both limbs hading east-south-eastward, and the 
limestone-bands are all so much alike in lithological character that 
it seems possible that they may belong to one bed which has been 
repeated by folding. The limestones occur in, or occasionally at the 
side of, a series of banded gneisses, micaceous gneisses or mica- 
schists, hornblende-schists and eclogite-rocks.* Where there are no 
faults, this series lies about 1 mile east-south-east of the sheared 
and inverted Lower Torridonian rocks of Kyle Rhea, and it is 
separated from these rocks by a band of siliceous mylonized rock and 
by a considerable exposure of flaggy granulitic quartzite which con- 
tains subordinate bands of garnetiferous biotite-schist. The mylonized 
rock dies next to the Torridonian Series, and the granulitic quartzite- 
series comes between it and the series with which the limestones 
are associated. There is little doubt that the mylonized rock occurs. 
along the line of a great post-Cambrian thrust, which has been traced, 
in a south-south-westerly direction, from Oronsay to near the Point 
of Sleat, and, as we are informed by our colleague, Mr. B. N. Peach, 
in a north-north-easterly direction for many miles on the northern 
side of Loch Alsh. The granulitic quartzite which occurs on the east 
side of the mylonized rock closely resembles the siliceous flagstones 
east of the Moine thrust * of Sutherland and Northern Ross-shire. 
It is perhaps unsafe to conclude that the thrust near Glenelg is 
a direct continuation of the Moine thrust of Sutherland; but these 
two thrusts have, at all events, played much the same part in 
building-up the geological structure of the districts in which they 
respectively occur. 


3 an the Occurrence of Sapphire in Scotland, Min. Mag. vol. ix (1891) 
, 389. 
at Summary of Progr. Geol. Surv. for 1897,’ pp. 36-38. 
3 An eclogite from Totaig has already been described by Mr. Teall, Min.{Mag. 
vol. ix (1891) p. 217. Similar rocks occur abundantly in Glenelg. 
4 See ‘Rep. on Recent Work of Geol. Surv. in N.W. Highlands,’ Quart. 
Journ. Geol. Soc. vol. xliv (1888) p. 412. . 


Vol. 55.] AND FORSTERITE FROM THE GLENELG LIMESTONE. 370 


Kast of the mylonized rock all the rocks of sedimentary aspect are in 
a greatly altered condition, and there are none that can be claimed 
with confidence either as Cambrian or Torridonian. The gneissose 
and schistose rocks in which the limestones occur closely resemble 
parts of the Lewisian Gneiss Series of Sutherland and Ross-shire, 
and we feel little doubt that they belong to this series. This, 
however, cannot be rigidly proved. 

The rocks next to the limestone are not always of the same kind, but 
no gneissose or schistose rocks are seen to cross limestone. Itseems 
probable that some of these rocks represent sediments which are of 
approximately the same age as the limestone, and were altered at 
the same time as it; but the rocks of this class are intricately 
intermixed with others which have rather the aspect of gneisses and 
schists derived from igneous rocks, and in our present state of 
knowledge it is sometimes extremely difficult to separate the one 
class from the other. Immediately under one of the limestone- 
exposures on the north side of the Little Glen of Glenelg, there is 
a schistose rock (7940) ! which contains many small flakes of brown 
mica and specks of pyrites. About 3 mile south-east of the same 
exposure, there is a garnetiferous biotite-schist which contains many 
small crystals of kyanite. Both these schists seem indistinguishable 
in hand-specimens from some of those metamorphosed sediments 
of the Braemar Highlands to which our attention has been called 
by our colleagues Mr. G. Barrow and Mr. E. H. Cunningham-Craig. 
Again, on the hill, nearly 3 mile slightly south of east of Lochan 
Cul a’ Mhoil (Ross-shire 6-inch map 123), there is a gneissose rock 
(7908) which Mr. Teall states to be formed essentially of layers of 
zoisite and microcline, mixed with other darker layers of pyroxene, 
calcite, and sphene. This rock occurs within 100 yards of a lime- 
stone, and it is undoubtedly allied in character to rocks found in 
close association with limestones in Donegal and in the South-eastern 
Highlands. Besides the above-mentioned rocks there are others, 
in the gneissose series, which may represent altered sediments. 
Among these we may mention especially a peculiar rock which 
contains tremolite, a colourless pyroxene, pyrrhotite, and abundant 
distinct scales of graphite. 


The relations of the granulitic quartzite series to the gneissose 
series and limestones are not yet made out with certainty, and it 
would be premature to attempt a full description of them. The 
quartzite series is repeatedly folded with the gneissose series, and 
its boundaries are approximately parallel to the adjoining outcrops 
of limestone. Thus, on first inspection of a geologically-coloured 
map, the quartzite and the limestone appear as if they might be 
parts of one great sedimentary series. Individual sections which 
expose the junctions of the two sets of rocks fail also to show any 
difference in the strikes of the foliations in the rocks. Yet it is 


1 Tn this paper the numbers applied to rocks are those of hand-specimens and 
thin slices which belong to the Geological Survey of Scotland, and are pre- 
served in the Museum of Practical Geology, Jermyn Street, London. 


376 MR. CLOUGH AND DR. POLLARD ON SPINEL [Aug. 1899, 


noticeable that rocks of different characters lie next to the quartzite 
in different places, and, in one or two localities, the alteration- 
products which characterize the limestone are found in contact with 
the quartzite, though in other places there are distances of several 
hundred yards between the quartzite and the nearest exposure of 
limestone. 

In all the exposures of limestone we are at once struck with the 
great number of pieces belonging to different silicates which project 
from the calcareous matrix of the rock. There are masses of a 
white augite—called diopside by Mr. Teall—which sometimes 
attain a breadth of several yards. Smaller lumps of this mineral, 
and pieces of some serpentine-like mineral, are so abundant that, 


taken together, they may equal the rest of the rock in quantity. _ 


The pieces of diopside are generally edged by a narrow rim, often 
about 4 inch thick, of some dark green, serpentinous substance. A 
thin slice (7918) was prepared for the examination of this sub- 
stance: no pieces resembling olivine were found within it, and 
Mr. Teall states ‘that it is not possible to determine with certainty 
the minerals out of which the serpentine has been formed.’ Some 
of the smaller pieces of diopside project several inches beyond the 
calcareous matrix, and are only connected with it by narrow neck- 
like constrictions ; these pieces remind us somewhat of the sponge- 
like forms which occur in certain portions of the altered Durness 
Limestone of Strath Suardal (Skye). 

Small flakes of mica, pale yellow macroscopically, are rather 
abundant, and in one locality, rather more than 3 mile east-north- 
east by north-east of Bailamhuilinn, large plates of a similar 
mica occur as much as 3 or 4 inches long, and full of inclusions 


of calcite. This mica has been examined by Mr. Teall, and he 


calls it phlogopite (7693). 

In severai places the limestone has a-banded appearance, as it 
shows many parallel layers, from 3 to 4 inches thick, which 
contain fewer of the serpentinous pieces than the rest of the rock 
does. These layers are often twisted and contorted, and they are 
occasionally seen to wind round lumps of the diopside. The 
smaller serpentinous pieces, including perhaps all those which are 
less than a hazel-nut in size, show no grains of diopside near their 
centres, and they are honey-yellow, pale green, dark green, or 
almost black. 

Thin strings of fibrous hornblende, either colourless or pale green, 
are often found along lines of movement, and are sometimes seen to 
traverse, and fault the sides of, the diopside-serpentine lumps. In 
one locality there are needles of tremolite which have been folded 
into a close succession of small V-shapes, and have been crossed 
by lines of strain-slip. The mass of the limestone is, however, not 
aftected by such movements, and there can have been but few 
deforming or mylonizing movements near the limestone since the 
development of the minerals now characteristic of it. In this 
respect the limestone offers a strong contrast to the limestone which 
occurs in the Archean rocks of Letterewe (Loch Maree). 


Vol. 55.] AND FORSTERITE FROM THE GLENELG LIMESTONE. 377 


Besides the minerals already mentioned, and besides the forsterite 
and the spinel, we have also noticed in the limestone various scales 
of graphite, in association with small quartzose lumps, and a rather 
dark hornblende, either in scattered crystals in the calcareous 
matrix of the rock, or aggregated together into rather large lumps 
and containing many inclusions of a colourless pyroxene (7694). 

The thin slices of specimens obtained from rather more than 3 
mile north-north-west of Bailamhuilinn (7690), and from 3? mile 
above the foot of Allt Easan Mhic Gorraidh (7917), show the small 
serpentinous granules which are so abundant in the limestone. In 
these slices all such granules are seen to consist either of serpentine 
or of a partially serpentinized mineral, with high refraction and 
strong double refraction, which closely resembles the olivine of many 
eruptive rocks. This mineral is also indistinguishable optically 
from the olivine-mineral in specimen 7923, from rather more than 
2 mile east of Sgiath Bheinn ; the last-named has been analysed, and 
has thus been proved to belong to the variety called forsterite. 
The olivine-serpentine granules in slice 7917 are often from 
2to3mm. long. Within them are many parts which consist of 
fresh olivine, and are quite colourless when viewed by transmitted 
natural light, but these parts are separated one from another 
by thin anastomosing veins of serpentine and of some black 
granular ore, like those common in the olivines of other rocks. 
‘The black parts are sufficiently numerous to cause many of the 
granules in the hand-specimen to appear almost black. The 
granules are rounded or rather irregular in outline, and they show 
no well-defined crystalline faces or cleavage. Grains of diopside are 
abundant in the same slice, and they sometimes form thin rims 
round the olivine-serpentine granules. 

Spinel has not been noticed, except in the exposure rather more 
than 2 mile east of Sgiath Bheinn.* Here it occurs in grains, often 
from 2 to 5 mm. in diameter, embedded in lumps 2 or 3 inches 
long, which project slightly from the limestone and weather in 
most parts with a brown crust. Besides the spinel, these lumps 
contain also forsterite, serpentinous products of decomposition, 
diopside, calcite, and a few flakes of phlogopite. The grains of 
Spinel are at once distinguished in the hand-specimen by their 
almost opaque, pale blue colour. They sometimes occur in close 
contiguity, and are so numerous that perhaps they form a fifth or a 
sixth part of some of the lumps. The greater part of each lump is 
evidently composed of forsterite or of the yellowish-green serpen- 
tinous streaks which are closely associated with it, and give the 
prevailing colour to the polished face of the specimen. The 
forsterite-serpentine pieces are like those in specimens 7690 and 
7917, except that they are rather larger and much more closely 
aggregated together. They contain inclusions of all the other 


1 [Since this paper was read, spinels have been found in other localities. In 
some of these localities the mineral occurs in fairly well-developed octahedra, 
apparently black, but really dark green. Spinels of a violet colour have also 
been noticed in the locality near Sgiath Bheinn.— June 14th, 1899.] 


378 MR. CLOUGH AND DR. POLLARD ON SPINEL [ Aug. 1899, 


minerals which we have stated to occur in the lumps. The spine} 
has a conchoidal fracture and a vitreous lustre in the broken faces. 
A few of the grains visible in the hand-specimen show small faces 
of some crystal form, but Mr. Teall was unable to recognize any 
face of a well-defined form, and the outline is often rather curved 
or slightly mammillated. When the slice is viewed by reflected 
light the spinel shows the same bluish colour as it does in the 
hand-specimen ; but it is noticed that this colour is frequently less 
pronounced near the exterior of the grains than it is near their 
interior, there being often a thin rim (from 02 to ‘05 mm. thick) 
which contains streaks of different colours, some of them blue like 
the internal portions of the grains, and others of a brownish tint. 
Some of the streaks are slightly curved, but have a general 
direction nearly at right angles to the nearest side of the grain. 
Others are straight, and are either parallel one to another or cut 
one another obliquely, and they perhaps indicate a crystalline 
structure. In the thin slice all parts of the grains are transparent.. 
The parts that seem bluest by reflected light have a faint brown 
colour in transmitted natural light, while some of the marginal 
streaks are nearly colourless. When rotated with crossed nicols. 
some of the blue parts allow a certain amount of light to pass 3. 
they are not quite so black as some of the marginal streaks. Many 
of the grains are crowded, particularly near their centres, with 
small inclusions of calcite, phlogopite, and diopside, and perhaps: 
nearly a quarter of the mass of some of the grains is composed of 
these inclusions. The grains are also crossed by many irregular 
cracks, some of which are filled with calcite, but we cannot discern 
any deformation. 


SEPARATION AND ANALYSIS OF THE MINERALS. 


The rock'was powdered in a steel mortar, passed through a sieve 
with meshes measuring about -22 mm., and the finest powder was: 
removed by sifting through cambric. Methylene iodide (sp. gr. 3°32) 
was used to separate the minerals. 

The first fraction was fairly pure spinel, with some forsterite 
and a few grains of iron, probably from the mortar. The latter 
were removed by a magnet, and the sample was again separated, 
with the result that almost pure spinel was obtained (weight about 
1°3 gramme). 

The methylene iodide was then diluted to about sp. gr. 3°29, when 
a second fraction of spinel came down, less pure than the first. This 
was again separated, giving -4 gramme of fairly pure spinel, which 
was used for preliminary examination. On further diluting the 
methylene iodide to sp. gr. 3°2 the first forsterite fraction was 
obtained. This contained a few grains of spinel, which were almost 
entirely removed by a re-separation in methylene iodide of sp. gr. 3°3, 
and about 2 grammes of practically pure forsterite were obtained. 
Asecond fraction of forsterite was obtained on diluting to sp. gr. 3°15. 
This was less pure, containing some yellowish grains. Its weight 
was about ‘6 gramme, and it was used for preliminary examination.. 


Vol. 55.] | AND FORSTERITE FROM THE GLENELG LIMESTONE. 379 


The specific gravity of each mineral was determined in a pycno- 
meter with the purest samples, and the results were :—for spinel, 
3°57; for forsterite, 3°24. 

The results of the analysis of the spinel (weight of substance 
='391 gramme) are :— 


poi O ge Si Ice Wait th anne heh ete i Ree 1:20 
mA ©. VAltiminay eesek eaten nen aseaee es ee 69°80 
HeO.) ‘Merrous oxides so... cee 2:03 
RTo@); Waaviestiy cs... onecnacnacidesbepenceseaee 27°30 

100°33 


Or, SiO, : Al,O; : (FeMg)O. 
Ope le ese Oe 


The results of the analysis of the forsterite (weight of substance 
='500 gramme, and for FeO -256 gramme) are :— 


LO em OU Pasar c ee en cnn te dates vesesscns 41:16 (trace of TiO,) 
24) O78 2UN0 000 0c aan eee ee 1:02 
He@ (Herrous ORs” bic. cieessspicicmawsns 2°00 
‘BP(O) WILT 3 Baers cc Ue eee ae ae ‘26 
MnO Manganous oxide .................. "26 
MIO Pa gieSte «cos csdcaacencs cu asccovees 54:86 

Oss OMIANIEION 0. 52...s0006ecesen ‘70 (trace of F) 

100°26 
Or, SiO, : (Mg, Fe, Ca, Mn)O: A1,0, 
687 : Alt hah Od 


The small amount of alumina in the forsterite is in all probability 
due to a trace of spinel. 


In conclusion, we wish to express our great obligation to our 
colleague, Mr. J. J. H. Teall, F.R.S., who has determined the 
minerals in the thin slices to which we have referred, and has also 
helped us in other ways. We have also to thank Mr. Pringle, 
of the Jermyn Street Museum, and Mr. Prior, of the British 
Museum (Nat. Hist.), for searching out specimens to compare with 
those from Glenelg. The spinel of Glenelg closely resembles that 
from Aker in colour and mode of occurrence, but in the latter 
spinel crystalline form is better developed. One specimen in the 
Ludlam collection from Aker bears a striking resemblance to the 
Glenelg specimens, and shows the spinels embedded in a limestone 
“which also contains phlogopite and diopside. 

Attention should, moreover, be called toa paper by EK. Weinschenk,’ 
in which he describes various minerals, including forsterite, spinel, 
and phlogopite, that occur in the limestones accompanying the 
graphitic beds north-east of Passau. As already stated, there are, 
near the Glenelg limestones also, various bands of rock which are 
rich in graphite. 


1 <« Beitrage zur Mineralogie Bayerns,’ Zeitschr. f. Kryst. vol. xxviii (1897) 
p. 315, and reviewed in Neues Jahrb. 1898, vol. ii, p. 20. 


380 SPINEL AND FORSTERITE FROM GLENELG. [Aug. 1899, 


Discussion. 


Sir A. Grrxie referred to the exceedingly complicated geological 
structure of the district described by the Authors of the paper, and 
to the great interest attaching to the traces of sedimentary materials 
associated with the gneisses and other crystalline rocks. The 
Lewisian Gneiss of the region consists of enormous lenticles, many 
miles in horizontal extent, which have been torn away from the main 
mass of the formation and have been pushed westward over younger 
parts of the pre-Cambrian Series. The sedimentary materials 
referred to are probably the oldest in the British Isles. No trace 
of organic remains is to be expected among them; but possibly 
such researches as those detailed in the excellent paper to which 
the Society had listened might lead to the establishment of certain 
mineral characters by which particular groups of sediments might 
be identified, and an additional clue might thus be obtained in 
unravelling the extremely difficult structure of the ground. 
Whether this hope were fulfilled or not, it was satisfactory to have 
the problems attacked in so careful and exhaustive a manner as that 
followed by the Authors. He congratulated the Society on the 
addition to its effective strength by the admission of Dr. Pollard as 
a Fellow that same evening; and he alluded to a serious accident 
sustained last spring by Mr. Clough, in consequence of which that 
active and minutely painstaking geologist had been disabled from 
field-work during the whole of the rest of last year. 

Mr. J. J. H. Teatt also spoke. 

Dr. Pottarp, in reply to a question, said that he could not state 
exactly how much of the material occurred ; probably the occurrence 
was not very extensive. 


as 


Vol. 55.] THE GEOLOGY OF THE DAVOS DISTRICT. 38k 


25. The Guotoey of the Davos Disrrict (SwirzertanD). By A. 
VauGcHan Jennines, Esq., F.L.S., F.G.S. (Read May 10th, 


1899.) 
[Puates XXVI & XXVII—Map & Section. |] 
ConTENTs. 
Page 
I. Introduction.—Position and General Geological Structure of the 
DD IBERICED Sou todasieusieotge deh sdoeuohaben Oosweadeomodesdteonqucacesvod- dade su aaee 381 
II. The Rocks of the District............... fea aiatiare wich eamieeiue cea sh ged tenia eke 383: 


(a) The Chief Rock-systems present. 
(0) The Rocks of Limited Distribution. 
hie The Mectonies,of the: Disthiets 4.0. vy. dacs.s sdeben qneguels Ueecbacdaegadaees 399° 

(a) The Nature and Number of the Mountain-folds. 

(6) The Three Hasiern Folds, and the Formations present in 
them. 

(c) The Western Fold, and its Special Features. Suggested 
Explanation of these, and PEEL of the Rocks with 
those of the other Folds. 

ven Summary, OF, COnClIStONs: 22. ..<5.</vensnesweces.casewecenenataceteemaaones 411 


I. Inrropuction. 


Towarps the east of Canton Graubiinden lie the mountain-ranges 
which surround the Valley of Davos, a valley now so renowned for 
the healing value of its climatic conditions, but till lately both 
difficult of access and remote. 

Those who know Davos only when the individuality of the surround- 
ing mountains is lost in the white brilliancy of its wondrous winter 
may, naturally enough, never be led to think of the nature and origin 
of the walls of their splendid prison ; but to the yearly-increasing 
number of those in comparative health who remain or arrive during 
the summer months there are features in the landscape which must 
attract attention if they do not excite enquiry. It is difficult for 
the most casual observer to avoid noticing the abrupt crags of the 
Cotschna ridge above Klosters, the steep-tilted slopes of the twin 
Schiahérner, the long level ridge of the Alteingrat, and in the 
southern distance the sharp silhouettes of the Tinzenhorn and the 
Piz Michel shutting off this mountain-valley from the western world. 

Some explanation of the changing contours and the varied colours 
of these barrier-mountains may be of interest to those who have 
looked and wondered ; but it is not only on such general grounds 
that a detailed description of the district is desirable. 

There are problems in the structure of the district of the greatest 
interest to all geologists, and regarding the nature and relative date 
of the great earth-movements which have resulted in the Alps as 
now known, it is a-district which should afford evidence to the 
enquirer, if not in all cases explanation. The age of the ‘ Biindner 
Schiefer,’ the origin and date of the serpentine and its associated 
red-and-green schists, the meaning of the great ‘ overthrust’ and 


382 MR. A. V. JENNINGS ON THE [Aug. 1899, 


its breccias, are all questions which no student of the Alps can 
ignore, and in the study of which he may here expect to find help. 

The following account does not pretend to be complete or 
exhaustive. It is a summary of the results of observations made 
during 1898, with the addition of notes jotted down in several 
previous years. 

Prof. Theobald’s map and the accompanying memoir, published 
in 1864, are splendid examples of the results obtainable by the 
enthusiasm and energy of a single student; but they necessarily 
require revision with the advance of knowledge, and are also 
beyond the reach of many who might obtain and read a shorter and 
more concise account. Prof. Steinmann has studied the district 
on the west round Arosa, and Prof. Tarnuzzer has worked at the 
structure of the Rhitikon. Dr. John Ball has investigated certain 
of the Davos rocks, but his work was petrographic rather than 
geological. There has been, I believe, no general account of the 
geology of the district, though many of its problems have been dealt 
with by Heim, Rothpletz, Mojsisovics, Diener, and others. 

The following works are those to which references will be found 
in the ensuing pages :— 


THEOBALD, 1864.—Beitr. Geol. Karte d. Schweiz, 2te Lief. Sheet 15 & accom- 
panying memoir. 

TARNUZZER, 1891.‘ Der geologische Bau des Rhatikongebirges.’ Jahresber. d. 
Naturf. Gesellsch. Graubiindens, vol. xxxv. Chur. 

STrEmnmaAnn, 1897.—‘ Das Alter der Btindner Schiefer,’ Ber. Naturforsch. Gesellsch. 
zu Freib. i. B. vol. ix, pp. 245-263 & vol. x, pp. 215-292. 

BALL, 1897.—‘ The Serpentine & Associated Rocks of Davos.’ Dissertation for 
degree of Doctor of Philosophy. Ziirich. 

BopMER-BEDER, 1898.— Ueber Olivindiabase aus dem Plessurgebirge.’ Neues 
Jahrb. Beilage-Band xii, p. 238. 


Herm, A., 1878.— Untersuchungen tiber den Mechanismus der Gebirgsbildung, 
Basel.’ 

Parona, 1891-92.—‘ Sugli Schisti silicei a Radiolarie di Cesana presso il Mon- 
ginevra. Atti R. Accad. Sci. Torino, vol. xxvii, pp. 305-319. 

Parona & RovERETO, 1895.—‘ Diaspri Permiani a Radiolarie di Montenotte 
(Liguria occidentale).’? Atti R. Accad. Sci. Torino, vol. xxxi, pp. 167-181. 


Position and General Geological Structure of the 
District. 


The Davos Valley runs approximately north-east and south-west, 
roughly parallel to the Vorder Rhein, Its present southern out- 
flow is by the Landwasser, which joins the Albula at Filisur. On 
the north a smaller stream flows into the Landquart at Klosters, 
and thus the drainage from either end is ultimately into the Rhine. 

The quadrilateral area between the Albula and Landquart, 
Landwasser and Vorder Rhein, is deeply incised from east to west 
by the Plessur, flowing into the Rhine at Chur. The watershed of 
the latter is the ridge of mountains west of Davos, forming the 
Aroser-Rothhorn group on the south, and stretching northward 
towards Klosters. Thus, on the west of Davos there is a mountain- 
ridge crossed only by foot-passes, the Parsenn-Furka Pass, the 
Strela Pass, and the Mayenfelder-Furka Pass. On the east are the 


Vol. 55. | GEOLOGY OF THE DAVOS DISTRICT. 383 


mountains of the Silvretta, Scaletta, Ducan, and Albula groups, — 
from which flow the Landquart, Fluela, Dischma, and Sertig rivers. 

From a geological point of view the next question is, what posi- 
tion do the valley and mountain-ranges bear to the general strike of 
the strata of the whole country ? While the general trend of the 
valley corresponds roughly to the line of the Alpine axis, it will 
be found that it does not follow exactly the strike of the rocks. 

The eastern mountains consist of crystalline schists and gneisses, 
but these also cross the Landwasser and form part of the western 
group. The limestones and dolomites of Parpan and Arosa can be 
traced to Klosters, and thus the strike of the strata is more nearly 
east-and-west than the geographical line of the Davos Valley. North 
of Klosters there is an apparently abrupt change, and the outcrop 
turns northward and westward: a band of limestone (easily trace- 
able by the eye from considerable distances) running obliquely 
north-westward across the Rhitikon, and finally merging into the 
mountains of the western Arlberg. 

In the neighbourhood of Klosters we have thus on the west the 
great mass of the grey Bundner Schiefer, and on the east a vast 
thickness of crystalline rocks; between them is a narrow band of 
limestones and associated rocks widening out northward, but of 
only slight thickness here, reappearing southward in the mountain- 
ridges which form the subject of our study. 

The general dip of all these strata is southerly and easterly, and 

as the crystalline rocks on the east are undoubtedly older than any 
of the neighbouring strata, it is evident that there has been a great 
overthrusting of the older strata over the newer from the eastern 
side. 
It remains to be seen whether it is possible to trace out the 
different elements of the complicated zone which lies between the 
more uniform areas of the east and west. Before attempting such 
an explanation, it is, however, necessary to form some idea of the 
different rock-formations present within the district, their character- 
istics in the field when typically developed, and the modifications 
that they may under certain conditions undergo. 


Il. Tuer Rocks oF tHE District. 


In deseribing the rocks it will, perhaps, make matters clearer if 
I refrain from attempting a stratigraphical sequence, but work 
inward from the outer boundaries of the region towards the complex 
area round which the more controversial questions centre. 

The whole series of rocks may be divided into two groups. In 
the first (a) are included those which cover the greater part of the 
map, and are more or less distinctly referable to certain great 
geological systems. In the second group (6) may be included rocks 
of limited distribution and doubtful age, occurring in a definite 
relative position, though with a confused and sinuous outcrop. 
These are the rocks which are found along the overthrust or 
‘Aufbruchszone’ of Steinmann, and in the Arosa district he 


384 MR. A. V. JENNINGS ON THE [Aug. 1899, 


regards them as ‘imbricated without regularity’ and presenting. 
a striking analogy to the ‘ Klippen’ of Iberg. 
Commencing with the former group (a), I proceed to consider 
first 
(i) The Older Crystallines. 


This heading 1s vague, and has obviously no precise geological 
significance, but it is a convenient term for descriptive purposes in 
the region under review. ‘The rocks so designated occupy the 
eastern part of the area, but are also evidently present in patches 
and streaks on the west of the Davos Valley. They are a series 
of gneisses and schists, building sometimes vast mountain-masses 
such as those of the Silvretta and Scaletta groups, or thinning to 
narrow layers such as the crystalline band under the Kiipfenfluh 
and the Schiahorn. ‘The dip is in general southerly and easterly, 
as is the case over the whole area, but there are local variations 
indicating the presence of acute-angled folds. The recurrence of 
similar types of rock at different levels along roughly parallel lines 
indicates that there is a considerable repetition of such folding, and 
that the total thickness of the beds was not originally so great as 
the height of such mountains as the Fluela Schwarzhorn and the 
Kihalphorn might at first lead the observer to suppose. 

In lithological character there is great variety. Besides the 
white coarse-grained ‘ eye-gneiss,’ conspicuous in the Fluela Pass, 
passing by gradations into quartzose schists, such as those seen at 
the mouth of the Dischmathal, there occur brown biotite-gneisses, 
of which the fragments are abundant in the Sertig Valley, and in 
bands over the whole district occurs a compact ‘ hornblende- 
schist’ streaked with veins of a yellowish-green epidote. 

It is not proposed in the present paper to contribute evidence 
as to the age or origin of these ‘older crystallines.’ It is probable 
that the quartzose series represent crushed and altered granitic 
rocks, while the ‘ hornblende-schists ’ may with equal likelihood be 
metamorphosed diorites. The biotite-gneisses, and many other 
rock-varieties not mentioned here, may well be the representatives. 
of ancient sediments, but as they are, so far as we know, entirely 
devoid of fossils, there is as yet no evidence for ascribing to them 
any definite geological age. They are, however, undoubtedly much 
older than any of the other formations present. 

Details as to the microscopic structure of various specimens of 
the gneisses and schists will be found in Dr. Ball’s paper.’ It is 
unfortunate that the limited time which he was able to give to 
the study of the district prevented his work from being of other 
than petrographic value. The distinction which appears on his 
sketch-map between the crystallines of the eastern and western 
sides of the lake does not really exist. He had not realized the 
direction and distribution of the mountain-folds ; and the prominence 
and crystalline character of the Casanna Schiefer on the south and 
west of the lake evidently led him to the view represented in his 


1 «Serpentine & Assoc. Rocks of Davos,’ Ziirich, 1897. 


Vol. 55.] GEOLOGY OF THE DAVOS DISTRICT. 385 


paper. He omitted to note that the ‘ hornblende-schists ’ and other 
characteristic rocks of the eastern side of the valley occur also on 
the Dorfliberg and the Korbshorn. 


(ii) The Bindner Schiefer. 


The term ‘ Biindner Schiefer’ has been used in different senses 
and with changing comprehensiveness by various writers. While 
referring chiefly to the great series of contorted grey argillaceous 
and calcareous strata which stretch across Graubiinden from Chur 
to the Oberhalbstein and from the Rhiatikon to the Upper Vorder- 
rheinthal, the name originally covered also the red-and-green 
schists associated with the serpentine. with the cherts, hornstones, 
and variolites. In Theobald’s memoir of this part of Graubiinden 
the term is used in this liberal sense. Steinmann, in his paper on 
the age of the Biindner Schiefer, has wisely proposed its restriction ; 
and in the following pages the name will be applied only 
to those strata which lie beyond the western limit of 
the dolomite and its associated rocks. The strata which 
form the Western Rhiatikon and the Schanfigg, cut through by the 
Landquart and the Plessur, consist of typical Bindner Schiefer in 
this restricted sense. They are, in the main, dark clayey shales 
locally seamed with calcite. The upper layers contain distinct beds 
of flagey limestone, and even thick and massive calcareous reefs. 

Despite the labours of many geologists, the age of the series is 
still a matter of great difficulty and uncertainty; and, as the 
present paper adds nothing to the controversy, it is unnecessary to 
go further into a description of the Biindner Schiefer. As is well 
known, the shales in some parts contain numerous fucoids, and these 
are usually regarded as of Tertiary age and referred to the Flysch. 
In other localities the discovery of ammonites and of bodies believed 
to be much-altered belemnites points to a Jurassic age, which on 
other grounds seems probable for a part at least of the series. 
Steinmann has tried to show that in some localities the line 
between the Tertiary and Secondary strata can be traced, and it 
may be that his conclusions will be confirmed by more detailed 
work, but the lithological similarity of strata of such different ages 
remains very difficult to understand. 


(ui) The Triassic System. 


After leaving the difficult problem of the grey Bundner Schiefer, 
we find ourselves on less uncertain ground in dealing with the pre- 
Jurassic strata. Taking them in consecutive order from above 
downward, it is found that 

(1) The Rheetie are the only beds characterized by definite 
fossils,’ though within our area these are few and generally crushed 

1 The only other fossils with which I am acquainted in the whole district 
are crinoid-fragments in the detritus on the Mayenfelder-Furka Pass, doubtless 
derived from the ‘ Mittelbildungen.’ 


Q.J.G.8. No. 219. 2 ¢ 


386 MR. A. V. JENNINGS ON THE [ Aug. 1899, 


out of recognition. The rocks form only small patches overlying 
the dolomite of the Ducan district, and certain crushed infolds 
ditficult to trace in the dolomite-ridges of the west. 

If one approaches the Ducan from Monstein by either of the 
valleys which converge there, one crosses a broad band of the older 
crystallines, then Casanna Schiefer and Verrucano, finally reaching 
the great walls of dolomite with their (in parts) almost vertical 
strata. 

In the northern valley, above the little lake at the foot of the 
Barenthali, are found numerous blocks of a grey limestone con- 
taining a branching-coral. These belong to the Lithodendron- — 
kalk, and form part of the Rheetic Dachsteinkalk formation. The 
corals are usually too much obliterated for paleontological study, 
but from comparison with those of other districts there is little 
doubt that they may be referred to Calamophyllia. Among these 
blocks are dark or black limestone-shales full of crushed shells, 
which stand out distinctly on the weathered surfaces, but are 
not sufficiently well. preserved for identification. There can be 
little doubt, however, that the beds were rightly referred by 
Theobald to the Késsener Schichten or Avicula contorta-shales. 
These strata, much tilted and contorted, can be traced by the 
eye, and are seen to form the upper part of the surrounding peaks 
and to extend upward and northward to the A‘lplihorn. The 
crumpled cap of the Krachenhorn, on the south, is composed of 
the same beds. 

West of the Davos Valley the Lithodendron-kalk is present on the 
Strela Pass and on the north side of the Cotschna ridge. I have 
not, however, traced the Kossener Schichten in these localities. It 
is possible that both occur in the Amselfluh fold, but I have not yet 
observed them there. 


(2) The Hauptdolomit.—As elsewhere in the Eastern Alps, 
this is the most conspicuous member of the Triassic system, forming 
many of the higher mountains of the district and weathering cha- 
racteristically into angular peaks like the Tinzenhorn and Schiahorn, 
or great precipitous rock-walls such as the Ducan, the Kupfenfluh, 
and the Amselfluh. The stratified nature of these, and the folding 
of the beds of which they are composed, are frequently conspicuous 
at great distances owing to the lingering snow-lines on shaded 
ledges. The Ducan and the Piz d’Aela are prominent examples. 

The rock itself is ight or dark grey, often streaked in all direc- 
tions with white calcareous veins and sometimes full of graphitic 
films, but devoid of fossils. The degree of dolomitization varies 
considerably, some specimens effervescing readily with cold acid 
and others very little or not at all. The specific gravity ranges, 
according to Dr. Ball, from 2°75 to 2°84, In the lower portion the 
rock may possess a more or less flaggy structure, and may be difficult 
to distinguish from the underlying limestones of the ‘ Mittelbild- 
ungen’; elsewhere the distinction is sharply marked. 

The great masses of the Hauptdolomit appear in some places 
isolated like those of the Ducan, in others they form a confused 


Vol. 55. ] GEOLOGY OF THE DAVOS DISTRICT. 387 


series of peaks, as in the neighbourhood of the Arosa Rothhorn, 
mixed up with other strata. When, however, this latter group is 
traced northward into the Davos district, it will be found to con- 
tinue in definite and separate ridges, the tectonic meaning of which 
will be discussed at a later stage. The westernmost line includes the 
Arosa Weisshorn and its surrounding slopes, and crosses the Arosa 
and Upper Plessur valleys to the Weissfluh, the Casanna, and the 
Cotschna ridge. The second forms the great series of crags on 
the east of the Arosathal: the Schiesshorn, Thiejerfluh, Midrigerfluh, 
Kupfenfluh, and the twin Schiahorner above Davos. The dolomite- 
region of the Lower Landwasser spreading round Wiesen is not 
prolonged so far to the north, but ends in the long ridge of the 
Alteingrat and the cliff-like wall of the Amselfluh. The south- 
easterly dip is prevalent in all these ridges, though occasionally, 
as near Davos itself, there may be a north-westerly inclination 
indicating the presence of minor folds. 


(3) The Mittelbildungen.—Theobald used this term as a 
general name for the beds which occur in Graubtnden between 
the Hauptdolomit and the Verrucano; and though the name does 
not express a sharply-defined geological series, it is convenient to 
retain it. In this position in the Austrian Alps occur various for- 
mations defined by characteristic fossils ; but in the Davos district 
we find only much reduced and widely varying representatives of the 
Arlberg-kalk, Partnach Schiefer, Virgloria-kalk, and Streifen Schiefer, 
with their associated beds of gypsum and rauchwacke. 

In the north of the district, beyond Klosters, the Hauptdolomit 
disappears, and in the limestone-band which runs thence towards 
the Calanda and Arlberg Theobald has traced almost all these 
beds. In other parts thin layers of the Arlberg-kalk and Virgloria- 
kalk can be often traced, with local patches of the other members 
of the group; but frequently, as in the Strela-Schiahorn ridge, the 
whole series is reduced to a thin layer of shaly limestone. 

(a) The Upper Rauchwacke.—Rauhwacke or rauchwacke is 
a yellowish limestone, sometimes dolomitic, with a characteristic 
vesicular or porous structure. It occurs on two horizons in the 
Trias. The Upper Rauchwacke often lies immediately below the 
Hauptdolomit, separating that formation from the Luner or Raibler 
Schiefer below, and it is commonly associated with beds of gypsum. 
In the Davos district it is frequently absent, but may be observed 
in the valleys north of Wiesen, and with gypsum-beds on the 
Gypshorn and the Strehl of the Ducan basin and on the north of 
the Casanna-Cotschna ridge. The latter is perhaps in the same 
geological position as the patch which appears between the Weissfluh 
dolomite and the serpentine of the Todtalp Schwarzhorn, 

(3) The Arlberg-kalk is generally a compact, fissile, dark- 
grey limestone, often partly siliceous. It is but slightly developed in 
this area, although fairly constant. A good example may be found 
on the Parsenn slope above Schwarzseealp, though it is not marked 
on Theobald’s map. 

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Volee ge THE GEOLOGY OF THE DAVOS DISTRICT. 389 


(y) The Partnach Schiefer are grey schists with calcareous 
bands, characterized elsewhere by special fossils. Theobald found 
them distinct on the Rhitikon, and has marked them in the Ducan 
basin and near Wiesen; but I doubt whether they are generally 
distinguishable. The ‘ Mittelbildungen’ on the Parsenn slope may 
be in part referable to them. 

(6) The Virgloria-kalk (Schwarze Platten- or Tafel-kalk) 
forms often a very distinct horizon, but here varies greatly. It 
is a dark limestone with tabular structure, and contains sometimes 
siliceous or ‘hornstone’-nodules. It is well developed and fossili- 
ferous on the Rhatikon, and distinct in the Ducan and Wiesen- 
Amselfluh regions, but thins out or disappears in the Strela fold. 

(e) The Streifen Schiefer, below the Virgloria-kalk, have no 
importance in the Davos area, though they have been mapped in 
places. 

(¢) The Lower Rauchwacke is similar in character to the 
Upper Rauchwacke, but often darker, less vesicular, and occasion- 
ally siliceous. It frequently includes fragments of older rocks, 
and tends to form a conglomerate passing into the Verrucano.* 
It seems to occur in the Ducan and Wiesen-Amselfluh areas, but I 
do not know of characteristic exposures nearer Davos. 


(iv) The Verrucano. 


Below the ‘ Mittelbildungen’ hes the problematic Verrucano— 
as constant in its presence as it is variable in character. The 
typical. red conglomerate, which has been variously referred to the 
Carboniferous, the Permian, and the Trias, is well developed in the 
neighbourhood of Wiesen and Glaris, and will be found in the form 
of thin bands on each side of the other limestone-ridges. Where 
the exposure is broadest, between the Korbshorn and the Amseltluh, 
it forms the steep ridge so conspicuous from the eastern side of the 
Davos Valley, culminating in the conical peak of the Kummerhubel. 
This, like the Sandhubel on the south, consists of a quartz-porphyry 
or quartz-felsite such as farther east attains so great a development 
in the vast sheets of porphyry that form the rich vineyard-country 

of Meran and Bozen and the more eastern Tyrol. 

Although the map suggests that the igneous rock forms sharply- 
marked intrusive patches, this is not really the case. ‘he 
congiomerate is often so full of felspars and corroded quartz- 
crystals that it seems to pass into the ‘ porphyry,’ and is a sort of 
‘quartz-porphyry- conglomerate’ such as that known in other 
localities. 

In parts the conglomerate becomes very fine-grained, and passes 
into a shaly sandstone. This, again, may become more argillaceous 
and so pass into the red shales or the mottled red-and-green beds 
that have been termed ‘Servino.’ Theobald also mentions the 
presence of masses of jasper and hornstone in the Verrucano (an 


' This is Theobald’s view. See also note on p. 394. 


390 MR. A. V. JENNINGS ON THE [Aug. 1899, 


important fact to which reference will be made later), as well as its 
association in parts with ‘ tale-quartzite.’ 

Apart from this most conspicuous mass, it may be mentioned that 
(1) it is well developed as a zone surrounding the Ducan basin ; 
(2) it can be traced on each side of the Strela ridge, being found in 
the Guggerthali on the south, and east of the Schiabach on the north, 
of the Davos dolomite ; (3) in connexion with the Casanna-Cotschna 
limestone-ridge it is found on the north side, though often mixed in 
breccia with other rocks, while on the south side the position in 
which it would be expected is occupied by red shales and cherts ; 
(4) it is to be found (in close association with the ‘ talc-quartzite,’ 
and also containing red hornstone) along the slopes of the Eastern 
Rhatikon above Monbiel and Klosters. 

Attention is specially directed to this distribution of the Verrucano 
in the Davos district, as it is of much importance in relation to the 
stratigraphical questions which are discussed on a subsequent page. 


@) The Casanna Schiefer. 


The name which has come into general use for a series of crystal- 
line or semi-crystalline rocks found constantly in Graubunden, 
where the lower sedimentaries, in the form of Verrucano, appear in 
contiguity with the ancient crystallines, might be naturally thought 
to refer to the Casanna Alp on the south of the Pratigau. This, 
however, is only one of the many cases in which the repetition of 
Jocal names in different regions of Switzerland leads to misunder- 
standing. The formation in question derives its name from the 
Casannua Pass in the Upper Engadin. It is difficult to give any 
exact description of the character of the schists that would be applic- 
able over an extended area. In parts there are foliated rocks so 
completely crystalline as to be classified as fine-grained gneisses, 
while elsewhere there are thin black shaly strata of a much less 
ancient appearance. So far, however, as the Davos district is con- 
cerned, the predominant rock is a micaceous schist with (in parts) 
evident graphitic layers and often a great quantity of yellow 
hydrated iron-oxide. These characteristics were not noted by 
Theobald, and, so far as I know, have not been elsewhere made the 
subject of remark; but in reference to the conclusions in later 
parts of this paper, it seems to me desirable to emphasize the fact 
of their occurrence. | 

On the Korbshorn, for instance, it is possible to obtain hand-spe- 
cimens which consist entirely of a white mica-schist with layers and 
masses of graphite and ochre. ‘The cuttings on the road from Glaris 
to Monstein show also large rounded masses, apparently conere- 
tionary, with a similar black and ochreous character. The yellow 
colouring of the rock now quarried above Frauenkirch, and the vast 
accumulations of ochreous earth in the Albertitobel, are similar 
evidences of the distribution of this type of rock. On the eastern 
side of the Davoser See, where the presence, in thin layers, of the 


Vol. 95.1 GEOLOGY OF THE DAVOS DISTRICT. 391 


limestone and Verrucano has been already mentioned, occur crystal- 
line rocks which are less coarsely crystalline than the ancient 
schists ; and in the slightly weathered surfaces exposed by the 
railway-cutting, the observer finds again the development of the 
dark and ferruginous patches which characterize the Casanna 
Schiefer in other localities. 

It seems, then, that although it is scarcely possible to give an accu- 
rate definition of the variable Casanna Schieter, while it is certainly 
hard to trace a division-line between them and the older crystallines 
on one side, and perhaps occasionally difficult to mark their junction 
with the Verrucano on the other, yet they constitute a definite local 
horizon with certain characteristics observable in the field, and 
always occupy a place between the Verrucano and the ancient 
erystallines. 

The geological age of these rocks is not easy to determine. While 
some of them resemble those regarded in other parts of the Alps as 
Carboniferous,’ some pass by gradations into the great mass of the 
older erystallines. 


(6) The Rocks of Limited Distribution. 


In the foregoing pages I have dealt with those rocks which 
more or less certainly represent great geological formations else- 
where recognizable, and are within this district to be traced in 
constant sequence from north to south and from east to west. 
There remains, however, a residuum of rock-types the study of 
which presents great interest, but at the same time great difficulty. 
They are found along a line following the general north-easterly 
and south-westerly strike from Klosters to the neighbourhood of 
Arosa, always in association with the westernmost development of 
the dolomite, and may be grouped generally under the following 
headings :—(i) The Serpentine, (11) the Red-and-green Schists, 
(iii) the Ophicalcareous Grits, (iv) the Radiolarian Hornstones, 
(v) the Breccias, (vi) the Diabases and Variolite, and (vii) the Tale- 
granite. 

(Gi) The Serpentine. 


The Alpine serpentines possess great interest, not only on account 
of the problems connected with the nature and origin of the basic 
magmas in the crust of the earth, but also because of their wide and 
yet restricted distribution, the difficulty of making sure of their 
relationship to surrounding strata, and their distinct unwillingness 
to yield to the enquirer the secret of their age. While their zone 
of distribution is singularly narrow as a rule, the east-and-west 
extent of their outcrop is very great. 

The serpentine of the Eastern Alps is a more continuous band 
than has been generally supposed, and that of Davos is probably 
connected with the serpentine which appears in the Lower Engadin 

1 Specimens from the Korbshorn and from the lower Cotschna breccia 


which I showed to Prof. Heim were at once compared by him with the rocks 
believed to be Carboniferous in the Glarus area aud elsewhere. 


392 MR. A. V. JENNINGS ON THE [Aug. 1899, — 


about Ardetz and the Piz Mondin, and with the outcrop at Mattrey 
on the Brenner Pass. Those on the western side, in the Pennine 
Alps around Zermatt, in the Val d’Aosta, at Mont Jovet, and at 
various localities farther south in the Cottian and Maritime Alps, as 
far as the coast between Genoa and Pegli, may perhaps belong to 
the same series of intrusions. 

In the Davos district the main mass of the serpentine constitutes 
the Todtalp, which rises on the north and west of the lake, and 
stretches westward to the Weissfluh, culminating in the precipitous 
black crags of the Schwarzhorn (2672 metres high). The eastern 
face of the mountain stands far back on the west of the Klosters- 
Davos road, and is deeply furrowed by the numerous streams which 
are fast eroding its green-and-purple slopes. At the foot of this 
eastern face the talus-heaps merge into a huge detrital fan, sloping 
eastward, and at Wolfgang overlapping the end of the pine-clad 
ridge that crosses the valley at this point. ‘There 1s every evidence 
of the removal of an enormous thickness of rock from this side 
of the mountain, and the striking proofs of great glaciation on 
the barren upper plateaux, specially mentioned by Theobald, show 
that it is not only aqueous denudation which has effected the change. 
Between the Meierhofer Thal, which bounds it on the south, and 
the Stutzbach, which flows from its northern limit, the serpentine- 
mass gives the impression of vast solidity and thickness, but this 
appearance is to some extent deceptive. There is no doubt that 
the serpentine constitutes only the most prominent part of a band 
dipping southward and eastward with the other strata of the district, 
overlying the rocks of the Parsenn slope, and disappearing below 
the crystallines of the Dorfliberg. On the west its sharply-marked 
junction with the Weissfluh dolomite can be readily traced by the 
eye from any high view-point, such as the Schiahorn; but, though 
it clearly crosses the Schaflager ridge and forms a tongue-like 
projection down the Haupterthal, it shortly disappears in the stony 
waste of this desolate valley. This is due, I believe, to a local 
overthrust, of which there is other evidence. 

If, however, the road down the valley towards Langwies be 
followed, the observer will note the reappearance of the serpentine 
on the hillside to the left beyond Kupfen. A broad zone of the 
characteristic colour will be seen striking obliquely across the 
shoulder of the foot-hills, and so disappearing into the Arosathal. 
In the latter valley its course is readily followed along the eastern 
side to Arosa, and on the west striking across to Maran. In this 
area it seems to lose its character as a simple band, and, as is the 
case with the associated strata, seems to be repeated, and as it were 
distributed in patches. ‘This I take to be due to folding, faulting, 
and denudation, not to the presence of separate intrusive masses. 
Leaving it here as the hmit of the district now under review, and 
returning to the eastern foot of the Todtalp, we have to try to 
follow it in a similar manner northward and eastward; and the 
task is by no means easy. 

At the sharp bend in the highway above the village of Laret, 


Vol. 555) GEOLOGY OF THE DAVOS DISTRICT. 393 


where the railway-cutting and the road are in close proximity, 
the serpentine is typically exposed. It disappears under the mass 
of moraine-material that lies between the Schwarzsee and the river, 
but will be found again high up on the shoulder of the spur 
between the Lareterthal and the Upper Pratigau, above the 
Rutiwald. The thickness of detrital material renders it difficult 
to fix on the exact point at which it crosses the Lareter Bach, but 
it must be nearly opposite the chalets of Ried. The patch 
between Selfranga and Klosters, with its limestone and Verru- 
cano, is, I believe, a great displacement or slip from above, and 
has no relation to the real outcrops of the different strata. From 
the angle of the hill above Riiti the band of serpentine drops steeply 
down to the east of Auje, and rises again obliquely across the 
Rhatikon to the west of Monbiel, where, so far as this area is 
concerned, it finally disappears. 

The rock itself 1s a typical serpentine, and differs little from that 
of numerous other localities. Dr. Ball has made it the subject of 
detailed study, and has shown that it must be regarded as an 
altered holocrystalline rock originally consisting of olivine, enstatite, 
and diallage, and therefore to be included under the heading of 
lherzolite. The more crystalline varieties pass by gradation into the 
completely altered form; in places, as on the Parsenn-Furka Pass, 
the crushing which the rock has undergone has produced numerous 
shining, slickensided surfaces and an almost fibrous structure ; 
elsewhere the rock is traversed by veins of chrysotile and by cracks 
infilled with calcite. In the latter case we have a transition to 
the mixed limestone and serpentine, or ‘ ophicaleite,’ which is con- 
spicuous in parts of the Todtalp district and above Monbiel. This 
rock occurs only near the lower edge of the serpentine, and is in close 
association with the ‘ mixed rocks’ to which it is now necessary to 
rerer: 


(i) The ‘Red-and-green Schists.’ 


In the immediate neighbourhood of the serpentine of the Eastern 
Alps occurs almost invariably a series of more or less schistose rocks, 
of varying composition, which are coloured pale green in Theobald’s 
map and lettered as ‘ Sv.’ or ‘ Rothe u. Griine Schiefer.’ 

Green schists seem to predominate in other areas, and it is often 
stated that the serpentine is intrusive in the ‘ Grune Schiefer.’ The 
typical ‘Griine Schiefer ’ are, apparently, not present in the Davos 
district, but there occurs instead a remarkable group of rocks lying 
below the serpentine and extending across the Parsenn slopes and 
the gorge of the Stutzbach. Along this zone the ‘ ophicalcites ’ 
into which we have traced the serpentine pass into beds in which 
the serpentine-layers alternate with reddish calcareous bands, or 
with red layers of an argillaceous character. It is nota case of 
regular alternation producing a definite banded structure, but a 
complete confusion of the three elements: the green patches of an 
evidently serpentinous nature, the limestone-fragments, and the 
clayey films. 


394 MR. A. V. JENNINGS ON THE [Aug. 1899, 


It seems impossible that these ‘ mixed’ schists should represent 
a geological formation referable to some particular horizon. Bearing 
in mind that the Arosa variolites occur similarly in combination 
with red and calcareous bands, and that (as Prof. Steinmann has 
shown) even more typical ‘Griine Schiefer’ may exhibit a sphe- 
roidal structure on weathered surfaces, it seems probable that the 
rocks owe their character to local conditions and are connected with 
the intrusion of the ‘ ophiolitic rocks.’ 


(ii) The Ophicalcareous Grits. 


I suggest this name for some peculiar rocks which occur only, so 
far as I know, in the neighbourhood of the Todtalp and the Parsenn- 
Furka Pass. The ‘ red calcareous rock ’ referred to by Dr. Ball is an 
example, but other varieties may be coarser grained, dark blackish- 
green in colour, and with grey argillaceous films. . 

It is difficult to find these rocks in position, but it will be noted that 
their area of occurrence is precisely where the field-evidence indicates 
the local overthrusting referred to on p. 392. I have not found 
them east or west of the upper Todtalp, and they do not seem to follow 
the strike of the strata for any appreciable distance. 

They are of a fine or coarse granular structure, and closer obser- 
vation proves that their chief constituents are calcite and serpentine. 
Considering the position in which they are found, it therefore seems 
probable that they are ‘ crush-grits’ of serpentine and limestone.’ 

Prof. Bonney, who has kindly given much attention to these and 
other rocks that I have collected, suggests the possibility of such a 
rock being produced by the washing down of serpentine-grains from 
a pre-existent shore. This seems quite possible in theory, but I 
believe it has not yet been proved to occur elsewhere. If such a 
process had occurred here we should expect to find the same rocks 
elsewhere along the strike of the stratified rocks; their extreme 
localization seems to favour the ‘ crush-grit ’’ hypothesis. 


(iv) The Radiolarian Hornstones. 


Along the crest of the Cotschna ridge runs a contorted band of 
red rocks, composed of cherts or ‘ hornstones’ passing into red 
shales. In thin sections the cherts are found to be crowded with 
radiolaria, and are doubtless the same as those found by Steinmann 
at Arosa, and regarded by him as of Jurassic or later age. In this 
locality I do not see how that opinion could be maintained. 

From the radiolaria themselves one can scarcely expect con- 
clusive evidence, since our knowledge of characteristic Triassic forms 
is practically nil. Dr. G. J. Hinde has been kind enough to 
examine the microscopic sections, and, though the condition of pre- 
servation is not satisfactory, he is able to recugnize some 15 generic 


1 Tt seems to me probable that some rock of this kind may have given rise 
to Theobald’s statement as to the transition of the Lower Rauchwacke into 
Verrucano. See p. 389. 


Vol s5-| GEOLOGY OF THE DAVOS DISTRICT. 395 


types.! He is of opinion that the general facies is not unlike that 
known from Alpine Jurassic rocks, but points out also that this 
facies is similar to that of the radiolaria obtained by Parona” 
from Cesana in rocks which, that observer believes, cannot be more 
recent than Lower Trias, and may belong to the Permian.? 

As Theobald has observed, there are similar siliceous ‘ inclusions 
in the Liassic Algauschiefer and in Lower Jurassic strata on the 
left: side of the Rhine.’ If there were thus a recurrence in Jurassic 
times of conditions similar to those of the early Trias, there is 
nothing improbable in the reappearance of a similar radiolarian 
fauna. 

The stratigraphical evidence, as I hope to show later on, for the 
pre-Triassic (or Lower Triassic) age of the Red Shales and Radio- 
larian Cherts is very strong, and it is somewhat curious that this 
view does not seem to have occurred to Theobald, who, in his 
description, has given strong reasons in its favour.* Thus, in 
describing the Verrucano, he states that the upper layers become 
‘shaly’ and pass into ‘red Servino’ (the shaly type of Verru- 
cano), ‘often with quartz-schists, red jasper and hornstein.’ 
Elsewhere, in describing his ‘rothe Schiefer,’ under the heading 
of ‘ Bundner Schiefer’ (using that term, of course, in its old and 
comprehensive sense), he again refers to the presence in them of 
hornstone, quartz-schists, and jasper. Then he points out that 
the red ‘Bindner Schiefer’ cannot be distinguished from the 
red Verrucano (Servino), and notes the presence of similar red 
layers in the Raibler and Liiner Schiefer (Lower Trias). The 
latter fact has also been mentioned by Heim.’ In describing the 
Verrucano he states that ‘in the upper strata, close beneath the 
Secondary formations . . . in the shaly argillaceous, mostly deep red 
altered beds, limestone and dolomite-concretions come in, which 
even join together to form thin bands of siliceous and argillaceous 
limestone.’ 

(v) The Breccias. 


Evidence of the breaking and crushing which many of the rocks 
have undergone during the earth-movements which produced the 
_Alps may be found at several levels in the Rhetic and other 
strata; but in addition to this local evidence of disturbance in 
particular layers there are certain areas near Davos occupied by 
distinct breccias of considerable thickness. JI am unable to say 
whether they are the same as those described by Steinmann, 


1 The genera represented are Spherozoum (spicules), Cenosphera, Cenellipsis, 
Spongoprunum, Lithapium, Rhopalastrum, Archicapsa, Sethocapsa, Dictyo- 
mitra, Ellipsoxiphus, Stawrosphera, Dicolocapsa, Lithomitra, Tricolocapsa (2), and. 
Theosyringium (2). 

2 Parona, ‘Sugli Schisti silicei a Radiolarie di Cesana presso il Monginevra,’ 
Atti R. Acead. Sci. Torino, vol. xxvii (1892) pp. 309 e segg. 

3 Parona & Rovereto, ‘ Diaspri Permiani a Radiolarie di Montenotte,’ idid. 
vol. xxxi (1895) pp. 177 ez seggq. 

4 Theobald, Beitr. geol. Karte d. Schweiz, 2te Lief. 1864, Petrograph. Introd. 
pp. 27, 33, 44. 

° Heim, ‘ Untersuchungen iiber den Mechanismus der Gebirgsbildung,’ 1878, 
p. 42. 


396 MR. A. V. JENNINGS ON THE [Aug. 1899, 


Tarnuzzer, and. others in neighbouring districts ; but in the Davos 
district there are, I believe, only two great bands of breccia, which 
may be termed the ‘ crystalline’ and the ‘ polygenic.? The former 
consists only of crystalline fragments, the latter of a varied 
assortment more specially described below. 


Fig. 2.—Specimen of ‘ polygenic breccia’ (reproduced from a 
photograph, t nat. size). 


V 


D 


V = Red Verrucano. T = Yellowish Lower Triassic 
D = Grey Hauptdolomit. limestone. 
S = Green Schist. 


The crystalline breccia occurs along the Upper Parsenn 
slopes, between the serpentine and the red rocks and dolomite of the 
Cotschna. Its crystalline character is evident, but it may be easily 
mapped as gneiss and schists, because it is often only the weathered 
surtace which reveals its brecciated character. On Theobald’s map 
it thus appears simply as gneiss; and in the accompanying memoir 
the main axis of the Parsenn ridge is referred to merely as ‘ gneiss.’ 
The railway-cutting at Laret Station offers an excellent exposure, 
showing both the character of fresh fractures and the appearance 


a 
—-- 


Wol.sg 5.4 GEOLOGY OF THE DAVOS DISTRICT... 397 


presented by the weathering of the rounded glaciated surface 
above. It will be observed here that two masses of the breccia 
occur, separated by a considerable thickness of red schists; but 
this duplication I take to be due to a fold. On the opposite side of 
the Lareterthal the same band is present, but apparently, like the 
other associated rocks, it thins out rapidly; it is yet, however, to 
be distinctly traced along with the serpentine above Monbiel. 
Westward from the Cotschna it seems obliterated by the over- 
thrusting of the serpentine, but is probably continuous with the 
crystalline band running below the serpentine towards Arosa. 

The constituents of the breccia are mainly white-mica schists 
and fine-grained gneisses, with fragments of white granite and 
aplite. I have not observed in it either the brown biotite-gneisses 
or the green hornblende-epidote schists which are so characteristic 
of the older crystallines of the eastern part of the district. 

On the north side of the Cotschna, below the dolomite-wall, there 
is also present a band of brecciated crystalline rock, which, if the 
view suggested below as to the structure of the country be correct, 
may really be a more highly altered part of the Parsenn and Laret 
band. It differs in having a considerable amount of interstitial 
black or ferruginous material, and in the fact that the crystalline 
fragments are oval and drawn out at the ends like the eyes of an 
augen-gneiss, while the sinuous curves of the intermediate lamin 
give to the surface of the rock all the appearance of a flow-structure. 

The polygenic breccia occurs also on the northern slope 
of the Cotschna toward the Pratigau, and immediately above the 
last-mentioned rock. This northern aspect is very difficult of 
study, owing to the enormous accumulations of detritus which fill 
the woods of its lower slopes. Only high above the chalets of 
Hinter dem Zug, and after crossing the stony plateau that les above 
the tree-level, is it possible to meet with clear sections of the 
mountain-rocks in situ. Here, above the mass of angular frost- 
detached blocks which lies along the foot of the great dolomite-cliff, 
will be found a band of breccia composed of angular fragments of 
grey dolomite and of yellow limestone of the ‘ Mittelbildungen ’ 
embedded at all angles in a paste of dark red Verrucano with blocks 
of red hornstone and green schists.’ (See fig. 2, p. 396.) 


(vi) The Diabases and Variolite. 


In neighbouring districts, along the outcrop of the serpentine 
there are several other basic igneous rocks, but their relationship 


1 IT wish to note the occurrence at this point of a very interesting rock 
made up of calcite with rounded grains of serpentine. I was unable to find 
its exact position in situ; but as it seems of very limited horizontal extent, and 
as it is associated with a green rock of evidently igneous nature, I am inclined 
to regard it as a result of contact-metamorphism. It seems that the crushing 
of such a rock might easily produce something like the ophicalcareous grits 
described above. Prof. Bonney, however, thinks that the serpentine may be 
derived. See also note on p. 398. 


398 MR. A. V. JENNINGS ON THE [Aug. 1899, 


to the serpentine is not yet worked out. In the Arosa area there 
is a considerable development of rocks of the diabase-group, mostly, 
according to Herr Bodmer-Beder,’ containing olivine: and the 
diorites, spilites, and aphanites of Theobald and others occur along 
the same horizon. The transition of the fine-grained types into 
‘Grune Schiefer’ was long ago observed by Theobald; Steinmann 
has recently again called attention to it and shown that many 
specimens of the ‘ Griine Schiefer’ are proved by their weathered 
surfaces to be variolitic in structure. The presence of red layers, 
and often hornstone and jasper, was also noticed by Theobald, 
and the rocks pass into ‘mixed’ schists like those of the Parsenn 
slopes near Davos. The variolites are doubtless offshoots of some 
of the igneous masses, and, I am inclined to think, of the less 
basic types. In the Davos area, where the diabase series is 
scarcely represented,” I have not yet seen any variolitic structure in 
the ‘ schiefer.’ 


(vii) The ‘ Tale-granite, 


The frequent occurrence near the horizon of the Verrucano of a 
white granite passing in places into an ‘ aplite’ or ‘quartzite’ was 
recognized by Theobald in Graubunden and has been observed by 
Heim farther west. It was termed ‘Talc-granit’ or ‘ Talc-quarzit’ 
by the former, but the white flaky constituent is, in many cases at 
least, muscovite; tourmaline also is frequently present. The age 
and exact relationships of the rock still remain to be worked out. 
In the Davos district it is conspicuous on the Mittelgrat, but I can- 
not say whether it here lies partly in the older erystallines or only in 
the Casanna Schiefer: in any case, if occurs immediately above the 
serpentine. On the Parsenn slopes it is found in fragments in the 
crystalline breccia, and near the Schwarzsee Alp appears below the 
serpentine and in contact with Lower Triassic limestone which is 
altered by it. East of the Lareterthal it is found in contact with 
and altering the red shales, and occurs again above Monbiel with Ver- 
rucano and radiolarian chert. It thus seems to be intrusive, and of 
later date than the Lower Trias, but its relation to the serpentine 
I have not been able to make out. Whatever this may be, it is of 
importance to note the well-recognized fact of the occurrence of the 
tale-granite always approximately on the horizon of the Verrucano, 
and its appearance here in association with the red shales and 
radiolarian cherts. 


1 «Ueber Olivindiabase,’ ete., Neues Jahrb. Beilage-Band xii (1898) p. 247. 

2 The dyke shown on Theobald’s map near Drusatcha is, if present, not in 
situ ; and the same may be the case with that at Selfranga. A small outcrop on 
the Parseun, near the Schwarzseealp, is, according to Dr. Ball, a fine-grained 
enstatite-gabbro. A rock found at the foot of the Cotschna cliff, in association 
with the marble with serpentine-granules referred to on p. 397, is of a more 
acid character. (The slice shows some grains of quartz, eaten into by magma, 
roundish felspars, rather crushed and decomposed, without definite character, 
and some rather corroded biotite: all in a matrix retaining traces of fluxion- 
structure, but with indications of pressure and much micromineralogical change. 
Probably once a rhyolite—T. G. B.) 


Vol. 55.] GEOLOGY OF THE DAVOS DISTRICT. 399 


III. Tue Tectonics oF tHE District. 


Having thus obtained some idea of the local distribution of the 
various rocks, an endeavour may now be made to distinguish the 
interrelationship of the different outcrops and to form some idea of 
the true structure of the district, so as to represent it by a series of 
sections or by a model. 

While Theobald’s map is on the whole remarkably accurate, it 
will be at once evident to a geologist that the sections which accom- 
pany that author’s memoir are far from representing the conditions 
which actually prevail. The nature of mountain-folds was in 
Theobald’s time but inadequately realized, and it seemed impossible 
to represent the ancient crystalline rocks as lying above and parallel 
to sedimentary strata of Mesozoic age. Hence we find the dolomite 
and its associated rocks represented as forming shallow basins on the 
edges of upturned schists and gneisses. 

Since the publication of Theobald’s memoir no attempt, I 
believe, has been made to explain more exactly the structure of the 
Davos region, and to bring our reading of it more into accord with 
the growth of our knowledge of mountain-building. The view which 
I here venture to put forward explains, I think, as nearly as possible 
the different outcrops actually observed; at the same time it perhaps 
throws some light upon the nature of the doubtful rocks of the district, 
and brings new elements into the consideration of its more inter- 
esting problems. It may be added that the explanation suggested 
was arrived at from observation of the mountains themselves, not 
from astudy of the map; and that the sections here reproduced are 
sketches made in the field from such comprehensive points of view 
as the summits of the Alpliborn, the Jacobshorn, the Schiahorn, 
and the Kupfenfiuh. 


The repetition of such rocks as the Verrucano and the Casanna 
Schiefer on each side of the different outcrops of limestone and 
dolomite shows at once the presence of a series of folds in the 
district, while the almost constant south-easterly dip of all the 
strata indicates that the folds are, as a rule, compressed or flattened 
and have undergone pressure and thrusting from that direction. 
A study of the simplest fold, that of the Ducan, shows that the 
Secondary rocks occupy the troughs of the folds, while the older 
erystallines form the anticlinals between them. 

It is by no means easy to be sure of the number of the folds 
present, more especially where they are approximated in the south 
and west: but I believe that, within this area, there are four 
distinct synclinals, which may be enumerated as follows :— 

| (1) The First, Eastern, or Ducan Fold. 
a 


(2) The Second or Wiesen-Amselfluh Fold. 
(3) The Third or Strela Fold. 


6 (4) The Fourth, Western, or Arosa-Cotschna Foid. 


The first three are of comparatively simple character, composed 
of rocks referable with more or less exactness to definite geological 


400 MR. A. V. JENNINGS ON THE [Aug. 1899, 


systems. The western fold is that which is thrust over the grey 
Bundner Schiefer of the Schanfigg and Pritigau, and is complicated 
by minor folds as well as by the presence of the serpentine with 
its associated diorites and variolites, red cherts, red-and-green schists, 
and breccias ; all of which, as to their age and origin, are still the 
subjects of controversy. 


The First or Ducan Fold. (Pl. XXVII.) 


The first fold comprises the mountains of the Ducan district. The 
pass of that name, which connects the head of the Sertigthal, by a 
narrow saddle at a height of 2760 metres, with the valley leading 
down to the Albula, is flanked on either side by conspicuous masses 
of the Hauptdolomit and its associated limestones ; while a broad zone 
of Verrucauo and Casanna Schiefer fringes the isolated tract and 
shuts it off from the surrounding sea of crystalline rocks. 

From the fact that a distinct south-easterly dip is observable on 
the Davos side, while a corresponding north-westerly inclination is 
noted near the Sertig Pass, it might be concluded that, in this 
case at least, one is dealing with a simple trough or basin; but 
no geologist who has crossed the Ducan Pass or approached the 
ridge from Monstein can fail to see that so obvious an explanation is 
remote indeed from the truth. 

The vertical position of the limestone-strata along the ridge 
formed by the Gypshorn, the Krachenhorn, and the Strehl, and the 
contortion of the overlying beds, show that a simple open synclinal 
is far from an adequate representation of the facts; while the 
occurrence along the axis of a sort of ‘inher’ of the Lower 
Limestones suggests that there is a minor anticlinal, a ‘ knee’ 
projecting upward in the centre. In other words, there is evidence 
that even the Ducan ‘basin’ is double and oblique, affected by 
that pressure from the east which is conspicuous in the surrounding 
area, but far more evident in the western folds. ‘The diagratimatic 
section (Pl. XX VII), of course, indicates only the dip of the strata 
in an east-and-west line, but it should be remembered that the 
‘ends’ of the synclinal area dip respectively southward and north- 
ward, thus accounting for the apparent southerly dip seen from 
Sertig on the Mittaghorn and Plattenhorn. 

The Rauchwacke, with its associated gypsum-beds, is well deve- 
loped, and a detailed study of the whole ‘ Mittelbildung’ series in 
this area is likely to prove of much value. 

It is, however, the presence of strata newer than the dolomite 
that gives to this region its special interest. On the west of the 
Ducan Pass several peaks are capped by beds which are of Rheetic or 
Liassic age. As already noted, the Lithodendron-kalk ( Dachsteinkalk) 
is present on the Strehl, the A{]plihorn, and the Krachenhorn; and 
the two former are also capped by dark shales with fossil bivalves, 
doubtless correctly referred to the Avicula contorta-beds. 


Vol. 55.] GEOLOGY OF THE DAVOS DISTRICT. 401 


The Second or Wiesen-Amselfluh Fold. (Pl. XXVIII.) 


The western margin of the Ducan ‘ basin’ is formed by the line 
of Verrucano and Casanna Schiefer which crosses the ridge between 
the Ailplihorn and the Leidbachhorn, and thence runs south-west 
towards Filisur. The dangerous crags of the Leidbachhorn and the 
slopes that lie below it towards the Landwasser Valley consist of 
the older crystallines. 

Round Monstein, however, when the solid rock is not hidden by 
the vast heaps of detrital material here accumulated, typical Casanna 
Schiefer and below them the Verrucano, which occupies the river- 
bed from Glaris to Hoffnungs Au, are again found. It is evident 
that here is the eastern edge of the second fold, the limestone 
portion of which forms both the long, level ridge of the Alteingrat 
and the more precipitous rock-wall of the Amselfluh. Along the 
north-eastern face of this remarkable ridge the stratification is 
evident: from a great distance, and from the lower slopes of the 
Kummerhubel the line between the Hauptdolomit and the Mittel- 
bildungen can often be traced by the eye. The Verrucano rises 
from below the limestone series, following roughly the course of the 
stream running down to Spinabad from the Mayenfelder-Furka Pass. 
It extends northward to form the Kummerhubel and the Schafgrind, 
and stretches as a broad band across the hillside to Staffel. where 
the Casanna Schiefer are turned up from below it. 

Though, on the whole, of a conglomeratic character, the Verrucano 
contains beds of a red sandy shale, while the Kummerhubel itself 
consists of the red quartz-porphyry already referred to. Above 
_Glaris some excavations made this year (1898) in connexion with 

hew electrical works show that the Verrucano-beds immediately 
below the limestones are mottled red-and-green shales of the 
*Servino ’ type. 

It is probable that, as in the case of the Ducan series, a detailed 
study of the different layers of the Mittelbildungen will repay the 
labours of future geologists; and it is probable that the Zzthodendron- 
kalk will be found somewhere in the Altein region. 

In conclusion, attention may be called to the view from Clavadel. 
Looking westward from that point, the succession of waves formed by 
the upturned margins of the formations constituting the Wiesen- 
Amselfluh fold is very distinct. On the right are the steep, rounded, 
deeply-incised slopes of the crystalline rocks which culminate in the 
Korbshorn ; on the left rises the limestone-wall of the Amselfluh, 
and in the centre the range of serrated peaks representing the Verru- 
cano-band, with the conical porphyry Kummerhubel as its middle 
point. Even the zone of the Casanna Schiefer, sweeping round from 
the Kummerthal under the village of Staffel to the slopes above 
Frauenkirch, can be to some extent traced by the eye, because of the 
rapidity with which it weathers and the pale yellow tinge of the 
resulting soil. 


Q.J.G.S. No. 219, 2D 


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s.Serpentine |j.Junction Rock] ¢.Crystalline Breccia R.Red Shales 


Vol ss2| THE GEOLOGY OF THE DAVOS DISTRICT. 403 


The Third or Strela Fold. (Pl. XXVII & figs. 3, 5 & 6.) 


This I have called the Strela fold, as it includes the mountains 
referred to by Theobald as the ‘Strelagebirge’: the Schiesshorn on 
the south, and in succession northward the Thiejerfluh, Madrigerfuh, 
Kupfenfluh, and Schiahorner. 

It will be seen that near the Mayenfelder-Furka Pass this fold is 
in close proximity to the western edge of the second fold, separated 
from it only by the band of Verrucano which lies in the long 
trough-like depression running from the Kipfenfluh to the Sand- 
hubel. This band seems to be the ‘knee’ of the intermediate 
anticlinal, the crystalline axis of the Korbshorn lying here below 
the surface, though it is doubtless continuous with the similar rocks 
near the Arosa Rothhorn. 

In this Strela fold the Mittelbildungen are very greatly reduced, 
and the great cliffs that overlook the Arosathal consist almost entirely 
of Hauptdolomit. It is interesting to note that the crystallines of 
the Korbshorn mass, running up as it were on the dip-slope of 
the Kupfenfluh, have not yet been entirely denuded from its summit, 
and thus the gneisses and schists of the Wannengrat actually cap the 
dolomite-ridge for some distance. 

On the Strela Pass itself the stony waste will be found to contain 
numerous fragments of the Lithodendron-kalk. Of its position 
an situ I am not very sure, but it seems to be a crushed infold of the 
strata noted on the western peaks of the Ducan group. 

The sharply-tilted rocks of the Great and Littie Schiahorner, with 
their precipitous northern aspect, indicate the approach to a region 
of still greater disturbance, while at the same time the rapid 
thinning-out of the beds becomes evident from the marked change in 
the scenery. Following the general line of strike northward and 
eastward, one might expect to see another ridge of calcareous crags 
stretching away by the Hornli towards the Silvretta, but nothing 
of the kind is visible. The lower plateau of the Little Schiahorn 
dwindles away to a narrow limestone-band (bordered by Verrucano), 
curving round behind Davos Dorf, and there vanishing below the 
superficial accumulations that fill the valley. 

On the opposite side, however, at the foot of the Seehorn, there 
is again a patch of dolomite continuous with a band on the east 
side of the lake. Theobald recognized the continuity of this with 
the Schiahorn band, but the matter is so much clearer now, owing to 
the rai]way-cutting, and is of so much importance to a right under- 
standing of the north-eastern part of the area, that it is necessary 
to note certain features in greater detail. (See fig. 3, p. 402.) 

At the point at which the railway nears the foot of the Seehorn, 
the solid rock that rises from the valley-alluvium, and forms the 
glaciated slopes on which the Basler Sanatorium stands, consists, 
mainly at least, of Casanna Schiefer. Where the line cuts the 
great roche moutonnée, a little farther on, the rock is seen to be 
a fine gneiss or micaceous schist with characteristic black and 
ochreous patches, evidently continuous with the band which is 

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Vol. 55.] THE GEOLOGY OF THE DAVOS DISTRICT. 405 


quarried on the opposite shore at the south-western corner of the 
lake. Beyond this first cutting, the right-hand bank shows a small 
exposure of shaly rock which proves to be certainly Verrucano. 
Succeeding this is the exposure of dolomite through which the 
second cutting runs, and as this dips down towards the lake we find 
once more above it a still more reduced representative of the 
Verrucano. Following immediately is a mass of Casanna Schiefer 
like that with which we started, constituting the last exposure of 
solid rock on the railway east of the lake. 

It is thus evident that all the elements of the Strela fold are 
still present, though greatly reduced; that they cross the valley 
from the Schiahorn to the foot of the Seehorn; that they border 
the lake on the east, and disappear at its northern end under the 
Wolfgang-Drusatcharidge. This disappearance is of great importance 
in connexion with the view which I have suggested elsewhere,! as 
to the nature of the Davos Valley and the former courses of its 
rivers, and shows that an investigation of the solid geology of the 
district confirms the opinions arrived at from physiographical con- 
ditions only. If the Wolfgang-Drusatcha ridge were composed of 
solid rock, in situ, one would expect to find this limestone-band 
striking across it; but, so far as I know, there is no trace of it. 
It is only by the Ménchalpthal that we find it again, but from 
here it can be followed round the shoulder of the mountain above 
Riti toward the Silvrettathal. North of this it reappears, and 
can be traced above Monbiel obliquely across the Rhatikon towards 
the neighbourhood of the fault in the Verkolmtobel. 


The Fourth or Cotschna-Arosa Fold. 
(Pl. XXVII & figs. 4-7, pp. 402, 404, 407.) 


In what I take to be the fourth of the series of folds comprised 
within the Davos district, the limestone-outcrops, by which the 
position of such folds is generally most readily traced, form the 
conspicuous masses of the Weissfluh and the Casanna. Between 
the Strela Pass and Langwies there seems to be a thinning of the 
calcareous band, but there is little doubt that the Casanna-Weissfluh 
line is continuous with that which crosses the Langwies-Arosa 
valley, runs round the slopes of Pretsch and Maran, and merges 
into the larger masses round the Arosa Weisshorn. 

It is true that, looking from the Strela Pass, one might at first 
be inclined to regard the Weissfluh as a direct extension of the 
Schiahorn fold, but the intercalation between the two of a well- 
marked crystalline zone shows that such is not the case; while the 
expansion of this band on the east into the great mass of gneiss 
and schists which constitutes the Dorfliberg (apart from the 
question of the serpentine Todtalp) will soon convince one of the 
distinctness of the two limestone-masses. The dolomite of the 
Casanna, which follows the Weissfluh on the north, is continued 
eastward to form the limestone-cliffs, so conspicuous from Klosters, 


* Quart. Journ. Geol. Soc. vol. liv (1898) p. 279, & Geol. Mag. 1899, p. 259. 


406 MR. A. ¥. JENNINGS ON THE [Aug. 1899, 


and it seems to me therefore that the continuity of this ‘ Cotschna 
ridge’ with the calcareous series west of Arosa can scarcely be 
doubted. It seems equally certain that, since both Verrucano and 
Casanna Schiefer have been traced alike above and below the 
limestone series, one is dealing here with a crushed synclinal fold 
such as that of the Strelagebirge and others already described. 

The difference lies in the greater intensity of the dynamical forces 
which have been in operation along the strike of this fourth fold, 
combined with the presence of rocks which are not represented in 
the three folds so far considered. The serpentine is obviously a 
new element; it is not present in the eastern folds. The main 
geological problems of the district are, firstly, its age and origin ; 
and, secondly, how far the rocks associated with it are represen- 
tatives of formations distinct from those already dealt with, or may 
represent the same strata modified or metamorphosed by the peculiar 
conditions to which they have been subjected. 

Before, however, entering into the arguments for the age of these 
problematic rocks, it is necessary to give some account of the local 
distribution of the different members of the group, and the best 
idea may be arrived at by following the successive outcrops north- 
ward from the Davos Lake. 

Returning to the Davos Valley, where the northern edge of the 

‘Strela fold crosses below the lake, the whole west side of the valley 
is seen to be occupied by the crystalline schists of the Dorfliberg. 
In the central part of this mass are the gneisses and the ‘ horn- 
blende-schist ’ already noted on the east as well as on the Korbshorn 
and Wannengrat ridges. The older crystallines are thus once more 
present here. The northern and southern margins of the mass seem 
to belong, however, to the Casanna Schiefer. The southern band 

.ineludes the quarries at the south-western corner of the lake, and 

“(as we have seen) reappears on the east. The northern outcrop 

borders the serpentine by the railway along the Meyerhofer Thali, 

- and forms the jagged, saw-like edge of the Mittelgrat, where its 
conspicuous element is a white micaceous or talcose granite. This 
can be traced in close connexion with the serpentine across the 
barren valley under the Schaflager, and so over the sharp ridge that 

here forms the watershed of the Davos and Plessur valleys. 

_ The line of crystalline rocks which may be termed the Dorfliberg 
anticlinal disappears in the rocky promontory at the north-western 

corner of the lake, but is found again in the stream-bed north of 
Unter Laret, and runs along the eastern slopes of the Lareterthal, 
over the Riiti ‘shoulder,’ between the Strela limestone above and 
the serpentine below, and so across to the Eastern Rhatikon. 

_ Westward it is continued as a narrow band under the Schiahorn 
and Kupfenfluh, and is here, I believe, thrust forward, together 
with the overlying dolomites, causing the local disappearance of 
the subjacent serpentine. Thus farther west, above Kiipten, where 
the latter rock reappears, the crystalline zone widens out, under- 
lying the chalets of Miadrigen, and striking south towards the 

. Arosathal. 


‘Vol. 55.] GEOLOGY OF THE DAVOS DISTRICT. 407 


The great serpentine-mass of the Todtalp, which rises from under 
the crystallines of the Dorfliberg, has already been studied as a rock- 
formation, but there are some features in its relationship to neigh- 
bouring strata that must now be referred to. Its upper limit (or 
southern margin) appears, as we have seen, to be directly overlain 
by crystalline schists or by white granite occurring in them; but 
there is evidence that this junction is due to an overthrust of the 
crystalline rocks. 


Fig. 7.—The Cotschna-Arosa fold : rock-exposure east of the Parsenn- 
Furka Pass, between the two streams which unite to form the Stutzbach. 


7 Ae 
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The lower margin presents still greater difficulty. On the 
western side the dark edge of the Schwarzhorn serpentine is 
sharply outlined against the dolomite and rauchwacke of the Weiss- 
fluh, but the absence of change in the character of either rock near 
the junction suggests again the idea of an overthrust or a fault. 
The thinning of the hmestone series at the Parsenn-Furka Pass, 
together with the disappearance here of the rocks of the Parsenn 
slope described below, all point to the same conclusion—that the 
‘same movement from the south-east, which has obliterated the 
serpentine in the Haupterthal, has pushed the Todtalp serpentine 
over the mixed rocks, which on the Parsenn slope lie between it 
‘and the Casanna dolomite. At the eastern end of the mass, by 


408 - MR, A. V. JENNINGS ON THE (Aug. 18995 


Laret Station, the railway-cutting shows that the base of the 
serpentine is almost in contact with the crystalline breccia described 
above.’ (Fig. 4, p. 402.) 

While the lower margin of the serpentine is thus easily seen 
both near the Parsenn-Furka Pass and at Laret, the conditions of 
the intermediate country are far less simple. 

The Parsenn area is difficult of study, as it consists mainly of 
steep grass-slopes with few satisfactory exposures of solid rock. 
It is, however, evident that the northern edge of the serpentine 
passes into the zone of ophicaleites, calcareous red-and-green 
‘Schiefer, which have been described in the foregoing pages. 
These rocks are well developed round the Mittelalp and along the 
gorge of the Stutzbach; they are represented by a narrow band 
at Riuti and above Monbiel, but cannot be seen in the Laret railway- 
cutting. Westward they disappear at the Parsenn-Furka Pass, and 
are only to be rediscovered towards Arosa. 

In the middle of the Parsenn slope the rocks are more distinctly 
shaly ; true red shales pass into green shales, and these, developing 
calcareous lamine, form a transition to thin-bedded limestones with 
argillaceous separation-planes, that one cannot help regarding as 
belonging to the Mittelbildungen. A _ little to the east (just 
above the forking of the Stutzbach) occur detached patches of this 
group of rocks carried up apparently by the serpentine, and here 
may be observed contorted strata composed of interbedded red 
shale and limestone. (See fig. 7, p. 407.) 

It appears, therefore, that on the Parsenn slope a secondary 
infold of the Lower Triassic rocks is present, separated from the 
qolomite of the Cotschna, but probably identical with the rock 
under the serpentine on the other side of the Lareterthal, and 
perhaps once continuous with the well-developed Mittelbildungen 
of the Haupterhorn on the west. 

Above and north of this narrow outcrop are low rocky crags, 
composed of brecciated crystalline schists with white granite. The 
interrelation of these is difficult to make out, but attention may here 
be called to the point where the general thinning-out takes place 
above the Schwarzsee Alp. The granite is certainly in contact with 
the dolomite, and the serpentine follows directly upon it. On the 
middle of the ridge, and rising as it were from below these crystal- 
lines, come the red rocks from which the Cotschna derives its name. 
They are contorted lenticular bands of red hornstone or chert full 
of radiolaria, passing in a short distance into ordinary red shales, 
such as were above noted as present in the near neighbourhood 
interstratified with the shaly limestones. 

The radiolarian cherts do not appear in the railway-cutting at 
Laret, where only red shales occur between the crystalline breccias, 


1 T am inclined to think that at this junction also the serpentine has been 
thrust over underlying beds, and crushed against the crystalline breccia. There 
is, it is true, a different rock at the junction, but it seems more like a crushed 
dyke-rock, perhaps of the diabase group, than a contact-product: it contains: 
fragments of a yellow limestone. 


Vol. 55.] GEOLOGY OF THE DAVOS DISTRICT. 409 


nor are they evident on the Riti slopes; but above Monbiel and 
Klosters they are distinctly developed, together with crystalline 
breccia and talc-granite, along the line mapped by Theobald as 
Verrucano, and in close connexion with Verrucano of the more 
usual conglomeratic type. 


The steep wall below the Cotschna ridge, and the spires of the 
Casannaspitz, evidently belong to the same line of Hauptdolomit, 
but there is a thinning in the centre, where the white bank of 
gypsum, so plainly seen from Klosters, indicates the horizon of the 
Rauchwacke. The band also thins out between the Casanna and 
the Weissfluh, while on the east it narrows towards Ried, but may 
be found again as a thin line on the Ruti slope and under the 
serpentine of the Eastern Rhatikon. 

The Lithodendron-kalk occurs in the detritus of the northern 
slope, and its presence indicates that the calcareous part of the 
Cotschna belongs to the series of crushed synclinal folds more plainly 
represented elsewhere, though it is evident that the upper limb of 
the fold is very different in constitution from that of the eastern 
representatives. 

Turning next to the lower part of the northern aspect of the ridge, 
with the view of ascertaining what strata reappear from below the 
dolomite, one finds considerable difficulty in determining outcrops 
with accuracy. The accumulation of talus-material is enormous, 
and the detrital slopes are thickly wooded. Theobald has mapped 
Verrucano, Casanna Schiefer, and ‘ gneiss,’ as well as the ‘ red- 
and-green schists,’ as occurring below the dolomite, and there is no 
doubt that the first three are represented by numerous blocks 
scattered about the slopes. Under the Cotschna ridge itself, how- 
ever, where one at last reaches the solid rock behind Hinter dem 
Zug, one finds that the strata below the dolomite are the two 
breccias already described. | 

The upper breccia occurs as a bed several yards thick, composed, 
as already stated, of angular fragments of limestone, dolomite, green 
schist, and quartzite, all apparently embedded in a groundmass of 
red Verrucano grit. The lower is the breccia of crystalline frag- 
ments, with the black and ferruginous matrix and the semblance of 
flow-structure, to which reference has also been made. 

What strata are present immediately below these breccias it is 
difficult to say.’ A short distance to the east, on the Klosters- 
Davos road, the grey ‘ Bundner Schiefer’ seem to underlie the 
attenuated dolomite directly, the breccias having locally dis- 
_ appeared. 


Such being the nature of the rocks in immediate association with 


1 It seems very probable that the serpentine, with or without red-and-green 
Schiefer, is folded with the other rocks; and it might be expected to reappear 
near the overthrust-plane. I have not represented this in the section 
(Pl. XXVII), as I have not observed it in the field. The serpentine-patches 
mapped by Theobald west of the Weisstluh and in the Arosa district seem to 
indicate, however, that such is the case. 5 


410 MR. A. V..JENNINGS ON THE [Aug. 1899, 


the limestone-band of the Cotschna, it remains to be considered 
whether they can be correlated with the formations noted else- 
where, or whether they belong to some geological series not yet met 
with. 

Starting from the south, and bearing in mind the succession of 
strata in the eastern folds, we should expect to find the older 
erystallines of the Dorfliberg followed by Casanna Schiefer. Such 
is the case along the Mittelgrat, though the typical schists are 
interrupted by the presence of a granite. Following it, where one 
would normally expect the Verrucano, comes the serpentine, and 
between this and the dolomite the series of problematic red-green, 
calecareo-argillaceous beds. When, on further examination, one finds 
that the green layers in this mixed ‘ Schiefer’ are obviously ser- 
pentinous, often even containing easily recognizable diallage-crystals, 
and when one remembers that on the Parsenn slopes above occur 
flaggy limestones of the Mittelbildungen distinctly interstratified 
with red schists, the conclusion inevitably suggests itself that 
the whole series of ‘Rothe u. Griine Schiefer’ (the ‘Sv.’ of 
Theobald’s map) result here from the intrusion of a peridotite or 
basic magma through a series of calcareous and argillaceous 
beds, representing in part the Mittelbildungen and in part the 
Verrucano. 

Fragments of fine-grained, though still distinctly conglomeratie, 
Verrucano occur on the northern slopes of the Stutzbach, but I have 
not found it im situ. It is, however, quite distinct on the same 
horizon above Klosters. The finer-grained or red-shale variety of 
the Verrucano is here predominant, and the red shales pass into 
Jenticular patches of red hornstone with radiolaria, which attain 
‘their maximum on the top of the Cotschna ridge, but also occur, 
‘together with typical Verrucano, on the Eastern Rhiitikon. 

Similarly, the brecciated crystallines of Laret and the Parsenn 
slopes, with the associated tale-granite and quartzite, seem to 
‘indicate a secondary fold between the serpentine and dolomite in 
which the Casanna Schiefer have been crushed and fractured by 
pressure and lateral movement. 

If our idea of the structure of the fold is correct, we should 
expect some of these formations to reappear on the northern slope 
below the dolomite, with still more evidence of the forces that 
‘have been at work, and it is precisely in this position that the two 
breccias above described are found. 

The conclusion, therefore, seems forced upon us that these are 
true friction-breccias formed in situ; that the upper one represents 
the lower limestones broken and, as it were, crushed into a paste 
of Verrucano; and that the lower is the same band as the brec- 
‘ciated crystallines of the Parsenn, corresponding to the Casanna 
: Schiefer of the other folds. This view seems in direct opposition 
“to the opinions of Steinmann, Tarnuzzer, and others who have 
, Studied the breccias of different parts of Graubiinden; but it is 
possible that those which they have regarded as derivative, and 
of Liassic or even Cretaceous age, may be on a different horizon 
from those of the Cotschna. 


Quart. Journ. Geol. Soc. Vol. L 


Pp IN THE DAVGS 


} miles. Heights are expressed 1 


COTSCHNA-AROSA H FOLD 


N. 
Cotschna ridge 
2267 m. 
jee 
. ° =-=-/ ‘ ~~.I>~ 
Crystalline breccia eel i [2a 
. . ~ ~ 
eee rs i he if > a 
r Ss. { ~ 
cs pce '{ Zonen \ 4 


‘Polygenic’ breccia \Red.Gre\s ’ 

Rar: 

SNe NaN SONUE \\ “‘s, Land wasser 
eo PAS 


Crystalline breceia ~~ 


x 


even % 
SQ@n LQ 
SS SASL SIAAS'SS 
GREY BUNDNER SCHIEFER SERPENTINFER VERRUCANO f 
Lias? Tertiary? ? Permian-Trias 


section runs south-eas{hiahorn and Klosters, in an approxima 
right half of the sectidorms no prominent mountain, such as 


Jote.—The above me geographical line. Through the fi 
somewhat more comp/schna and Parsenn region. 


The section is inte| 
(1) The gene 
(2) The sug¢e may not be (with the exception of 
geolojnd that the peculiar rocks which here 
explitphism. 
Tfolds, here brecciated in situ; (0) the ‘ 
togetlaud shales occur between the Verrucan 
with idotite-magma through the red schists a 


aS SS oe -\ Le 


Quart. Journ. Geol. Soc. Vol. LV, Pl. XXVII. 


SECTION OF THE MOUNTAIN-FOLDS IN THE DAVOS DISTRICT. 


(Scales, vertical and horizontal : ate or 1 inch = 1:6 miles. Heights are expressed in metres. | 


COTSCHNA-AROSA F (OLD STRELA FOLD WIESEN-AMSELFLUH FOLD DUCAN FOLD 
N. Ss: 
Cotschna ridge Todtalp-Schwarzhorn Schiesshorn-Schia- Amselfluh Alplihorn Hoch Ducan Piz Forun 
2267 m. 2672 m. -horn chain 2772 mM. ee 3010 m. 3066 m. 3056 m. 


Crystalline, breoia a [ie ae oe ae = See 
Radiolarian cherts He lt SSS 
in red shales». \ ue one of the | ny \ 4 
‘Polygenic’ breccia Aye y A Sbhiefers are WO 
Crystalline breceia ~~. Ma. = SS eam See NS 
“oS ~ NS SQ 
Sea Tm | | 
Klosters il NS \ 
un OQ \ 
ML. Sal WW \N 
Y OO 
SY FSV SS 
YM MY) KAM GG AXD.RRRRYN 


—— SEA LEVEL 
p SN 
SS 
GREY BUNDNER SCHIEFER SERPENTINE RED & GREEN ‘SCHIEFER’ OLDER CRYSTALLINES CASANNA SCHIEFER VERRUCANO ‘MITTELBILDUNGEN’ HAUPTDOLOMIT “LITHODENDRON-KALK’ &o. 
Lias? Tertiary? Older Paleozoic? Carboniferous? Permian-Trias Lower Trias Upper Trias Rhetic 


Note.—The above section is partly diagrammatic, as the peaks represented do not lie along the same geographical line. Through the first three folds (counting from the right) the line of 
section runs south-east and north-west ; the left end represents the conditions that exist between the Schiahorn and Klosters, in an approximately south-west and north-east line. The line of the 
right half of the section would cut the fourth fold in the hills aboye Arosa: there the serpentine-band forms no prominent mountain, such as the Todtalp-Schwarzhorn, and the folding may be 
somewhat more complex, but the essential structure is probably the same as that shown here in the Cotschna and Parsenn region. 


The section is intended to illustrate :— 
(1) The general character and distribution of the mountain-folds in the district; and 


(2) The suggestion that, in the fourth fold, which overlies the great overthrust-plane, there may not be (with the exception of| the serpentine and associated igneous rocks) any 
geological elements present which do not occur in the more normal folds to the east, and that the peculiar rocks which here characterize the neighbourhood of the serpentine are 
explicable as results of the igneous intrusion together with subsequent dynamo-metamorphism. 

Thus (@) the erystalline breccia seems to represent the Casanna Schiefer of other folds, here brecciated im sitw; (b) the ‘polygenic’ breccia is here a result of the crushing- 
together of Verrucano, Trias, ete. along the oyerthrust-plane; (c) the radiolarian cherts and shales occur between the Verrucano and the Trias, the shales being partly interstratified 
with the latter; (d) the ‘Red and Green Schiefer” result from the intrusion of the peridotite-magma through the red schists and lower limestones, 


Quart. Journ. Geol. Soc. Vol. LV, P 


Ye Y, Y 7, 7) = 
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Vol. 55.] _ GEOLOGY OF THE DAVOS DISTRICT. 4}1 


IV. Summary or Concuvustons. 


The results of the present writer’s observations round Davos may, 
then, be stated as follows :— 


The ancient crystalline rocks, perhaps originally Paleozoic sedi- 
ments traversed by igneous rocks of different kinds, have been much 
crushed and metamorphosed, thrown into a series of oblique folds, 
and thrust over the grey (Liassic?) ‘ Bindner Schiefer’ of the west 
and north. In the synclinals of these folds occur, south of the 
Pratigau, a series of infolds of Triassic and Rhetic limestones with 
Verrucano and ‘ Casanna Schiefer’ below them. 

Four such folds can be distinguished. The easternmost, forming 
the mountains of the Ducan group, is the simplest, and is an open 
fold though distorted. In the others, the two sides of the fold are 
erushed together, and the changes due to dynamic agencies become 
increasingly evident towards the west. In the second and third 
folds the Casanna Schiefer, Verrucano, and Lower Trias, while very 

variable, are, as in the first, of normal type, and not marked by special 
metamorphism. In the fourth fold similar little-changed rocks can 
be found at different points along the line of strike, but in other 
localities they are scarcely recognizable. In the Cotschna district 
the Casanna Schiefer are replaced by a band of breccia, folded on 
itself perhaps more than once, and reappearing below the limestones 
along the line of the great overthrust in a still more altered condition. 
The Verrucano passes into red shales, the upper layers of which are 

‘intercalated between strata of the shaly Lower Triassic limestones, 
and in the red shales lie ilenticular masses of red radiolarian cherts or 
hornstones. This group of rocks is crushed, with the Lower Triassic 
limestones, into a band of ‘polygenic’ breccia on the underside of 
the fold: that is, above the plane of the great overthrust. 

In addition to this, the structure of the fourth fold is vastly 
complicated by the presence of a band of serpentine. This rock 
is the representative of a peridotite-magma, injected apparently 
at some period later than the Lower Trias, but the district does 
not give satisfactory evidence for any later date. It probably cut 

‘ obliquely through the Casanna Schiefer and up into the Verrucano 
and Lower Trias, but there is no conclusive evidence in this district 
' of its penetration into the Hauptdolomit. Where it has forced 
its way through the stratified rocks, a remarkable formation 
occurs, the ‘ Rothe u. Griine Schiefer,’ which consist sometimes of 
lamine of serpentine and red argillaceous layers, sometimes of 
serpentine and red calcareous bands, and occasionally of a confused 
mass of all three elements veined and infiltrated with calcite. 
The radiolarian hornstones occur in the red shales thus invaded 
and altered. If the radiolarian rocks can be proved to be newer 
- than the Trias, the same must be true of the serpentine. If, on the 
other hand, the view here suggested as to the nature of the fold is 
. correct, they are stratigraphically below the dolomite, and we have 
‘here no evidence in favour of a post-Triassic date for the serpentine, 
. though there is nothing to disprove its post-Triassic, or even, as 
- others think, post-Cretaceous age. 


Quart. Journ. Geol. Soc. Vol. LV, Pl. XXVI. 
GES Seal 
YY Uy Yfyy f Yes, a7 
iy N Lz 


CASANNA SCHIEFER 


Carboniferous? 


LINES 
oz0ic? = 
‘L|THODENDRON-KALK' &c 
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£6029) 


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5287 
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HAUPTDOLOMIT 
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SSS== 


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RED & GREEN 
A 'SCHIEFER’ 


MITTELB/LDUNGEN' 


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SERPENTINE 


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Low 


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\ 5 % fe i = 
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{ S E < 255 ; = = oseullh, j 
HNN 5 oe 2 deo = B is 
3 ahs es = = ENG 
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GEOLOGICAL SKETCH-MAP 
OF 
THE DAVOS DISTRICT 


S S 
Ss ~ 
a 
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i ot 
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iS ry 2 >= 
iS x aN Lo aO§ 
iS — Se Se 
o Lae 
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Ss So 
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s é S bess 
My TH 
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Ly 
Ge 
GY 

Wy 
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412 THE GEOLOGY OF THE DAVOS DISTRICT. [Aug. 1899, 


EXPLANATION OF PLATES XXVI & XXVII. 
Puate XXXVI. 


Geological Sketch-map of the Davos District, on the scale of — 
or 1°6 miles to the inch. 


Puate XXVII. 


Section of the Mountain-folds in the Davos District, on the scale 
1 


(vertical and horizontal) of 100,000” 


or 1°6 miles to the inch. 


Discussion. 


Prof. Cote commented on the tendency in Alpine sections to 
represent the Casanna Schiefer as conformable below the Verrucano, 
and enquired as to whether this was not merely a generalization, 
based upon local occurrences of the one rock below the other. He 
presumed that the Casanna Schiefer belonged in this case to the 
underlying crystalline series. 

Dr. Hinpz also spoke. 

Prof. Bonney said that the term ‘Casanna Schiefer’ appeared to 
him rather vague, but it generally designated rocks of the crystalline 
group. He expressed his sense of the value of the communication 
which he had now been the means of making known to the Society, 
saying that on one point only he felt some doubt—namely, as to 
whether the serpentine was intrusive in the Triassic rocks. Of the 
peculiar ‘ ophicaleareous grits ’ on the western side of the serpentine- 
mass, three explanations might be offered: (1) that they were ‘ crush- 
grits, in which case, as it seemed to him, no conclusion could be 
drawn; (2) that some afforded evidence of contact-metamorphism, 
which would prove the Author’s point, but on which he thought there 
was room for much doubt ; (3) that the serpentine was present as 
fragments of a pre-existing reck, to which view, for reasons given, 
he personally inclined, though he admitted the question to be 
difficult, inasmuch as he had not visited the sections. Having 
expressed dissent on this point, it was only just that he should 
conclude by reading an extract from an answer which he had 
received from the Author :— 

‘With respect to the most difficult question dealt with in the 
paper, he regretted much that his conclusions did not entirely 
agree with these arrived at by Prof. Bonney from microscopic 
examination of the red-and-green Schiefer. He fully recognized 
the value and interest of Prof. Bonney’s theory as to the origin 
of these rocks, and was quite prepared to admit that it was a 
possible explanation and perhaps the true one. He felt, however, 
that the field-evidence for the intrusion of the serpentine through 
at least the Lower Trias was very strong indeed. If the serpentine 
were Paleozoic, and had contributed material to the formation 
either of the Verrucano or the Lower Triassic strata, he thought that 
the fact would be easily recognizable in other localities. The ve 
curious rocks in the neighbourhood of the Todtalp, which Prof. 
Bonney considered as favourable to his view, were so local in 
distribution, so restricted to a region of evident dynamic disturbance, 
intrusions, overthrusts, and brecciation, that the Author was inclined 
to regard them as due to these agencies.’ 


Vol. 55.] MAMMALIAN HUMERUS FROM TONBRIDGE. 413 


26. On the Distat Enp of a Mammatian Humerus from Tonsripex 
(Heurouvs uasor). By Prof. H. G. Szrtey, F.R.S., F.LS,, 
F.G.S. (Read May 24th, 1899.) 


Mr. R. D’A. AnpERson, of the Royal Indian Engineering College, 
has submitted to me the distal end of the right humerus of a 
mammal for determination. The bone was found in August 1898 
by Mr. Grenville Anderson, on the bank of the River Medway near 
Tonbridge (at a time when the river was running very low), when it 
was seen projecting from the reconstructed rock. The locality is 
not far from Messrs. Curtis & Harvey’s gunpowder-mills, at a point 
between a broken and disused lock-basin and an old bridge near the 
ballast-pit. On visiting the spot I found fragments of flints among 
the materials which form the river-banks; but although this might 
support a reference of the specimen to any geological period of 
subsequent date, there are conditions of mineral structure and 
osteological character which incline me to believe that the bone has 
been derived from the Weald Clay. 

When the fossil came under my notice, the distal end was broken 
from the shaft; and the shaft was split, showing the very thin 
condition of the bone of the shaft, and the hard, sandy, calcareous 
matter which filled the medullary cavity. Traces of matrix at the 
distal end show that the specimen has been derived from quartz- 
sand bound together with lmonite, such as might occur in the 
Hastings Sand, Weald Clay, or Lower Greensand, but the character 
of this matrix is opposed to the possibility of the specimen being of 
post-Tertiary age. 

The fossil, as preserved, is 4 inches long, and indicates a humerus 
which may have been 6 inches long when perfect, as large as that 
of a wolf, but smaller than in a bloodhound. 
~The shaft of the bone is flattened on the inner side, convex on the 

outer side, and thus it has a side-to-side compression approximating 
to half a cylinder, but is somewhat flattened towards the olecranon- 
pit behind. It is rather obliquely flattened above the condyles 
in front, making the shaft 2 inch deep on the inner side at the 
distal end, and rather less on the outer side. The side-to-side 
measurement is least, as usual, above the distal articulation. Towards 
the proximal fracture the depth of the shaft, which is augmenting, 
is ;9, inch from front to back, while the side-to-side measurement 
is =55 inch. 

The form of the shaft, flattened on the inner side, precludes any 
comparison of the animal with Carnivora, and indicates a resem- 
blance to Ungulate types. 

The distal articular condyles are set on to the shaft at a forward 
angle, which shows the animal to be terrestrial. When the shaft is 
held vertically, the condyles are anterior to it. There is no animal 
known to me in which this character is developed to the same extent. 

The extreme width of the condylar end of the bone is 12 inch. 
In narrowness of the condyles the character is somewhat pig-like. 
The external surface of the condylar end of the bone is convex and 


414 PROF, H. G. SEELEY ON THE DISTAL END- [Aug. 1899, 


narrow, without an appreciable lateral pit, a character of some 
interest, since all deer have the outer side of the condyle concave or 
with a central pit, while the vicufia (Awchenia) has a convexity. 
When the bone is held vertically and seen from the front, the 
condyles are oblique; because the outer condyle, which is the 
larger, then descends lower than the inner condyle. I have not: 


Heuionvus mM4sor, gen. et sp. nov.: distal end of humerus, nat. size. 


B. Seeley del. 


Anterior aspect. Posterior aspect. Lateral aspect. 


noticed this character in any other animal. The condyles are 
rounded from above downward in front, but almost inappreciable 
posteriorly. They are divided in front by a moderately deep 
vertical groove, which suggests the camel; though in that genus 
the external margins of the condyles are not rounded as in this 
fossil. The inner condyle is compressed from side to side to a blunt 
ridge, and this condition contributes to give the condyle a narrow 
aspect, which is exceptional. The outer condyle is flattened or 
traversed round its convex middle part by a very slight vertical 


Vol. 55.] OF A MAMMALIAN HUMERUS FROM TONBRIDGH. 415 


depression. Above the condyles in front there is the usual supra- 
condylar depression, somewhat deep and narrow. 

On the posterior aspect the distal end shows its most distinctive 
features. A long narrow olecranon-pit extends above the small 
external condylar surface. It is ovate in outline, filled with limonite, 
is 14 inch long and fully 4 inch wide in the middle. The inner 
border is comparatively straight and vertical, and the outer border 

is convex. 

The small external condylar surface below the olecranon-pit is an 
inconspicuous convexity about 7 inch deep. No part of the inner 

condyle is visible on the posterior aspect of the bone. 

The bone which margins the upper half of the olecranon-pit on 
the inner side is ;4; inch wide, rounded from side to side, but slightly 
worn. The external margin of the pit, which may also be a little 
worn, is about halfas wide. This character of the relatively external 
position of the olecranon-pit is seen in the humerus of the tapir, 
and to some extent among horses. . 

The lower half of the process which usually borders the olecranon- 

pit is absent in this fossil; and on the inner side, in its place, is an 
ovate cartilaginous surface, concave in length, inclined obliquely 
inward, making an angle of about 45° with the axis of the shaft. 
There is a similar, but much smaller, atrophy of the corresponding 
process on the external side, giving rise to a truncated surface, 2 
inch deep, forming a narrow crescentic impressed area. This 
character defines a lateral concavity between the hinder end of the 
humerus and the anterior border of the olecranon-process of the 
ulna. ‘This truncation of these parts of the humerus is especially 
common in antelopes and deer; but, in comparison with known 
types, recent and fossil, itis much more developed in the Tonbridge 
fossil animal. There is no Tertiary mammal in which the character 
is s0 conspicuous as in existing types. If Hyracotherium or Plio- 
lophus has the distal end of the bone placed as tar forward on the 
shaft, it entirely wants the truncation of the bone on the lower 
borders of the olecranon-pit; and there is no other fossil genus 
with which the specimen has a closer affinity. This consideration 
is perhaps evidence against the fossil being derived from some 
Tertiary stratum and accidentally left where it was found, and so 
far is favourable to the specimen being of Wealden age. 

On the whole, the weight of evidence from comparison with other: 
types appears to incline towards reference of the fossil to the Artio- 
dactyla, though there are almost as many points in common with 
the Perissodactylate humerus. In neither is the hinder part of the 
distal articulation of the bone comparable to this fossil. I therefore 
infer that it indicates a new family type. ‘he teeth described by 
Mr. Smith Woodward and by Mr. Lydekker are indicative of much 
smaller mammals from the Wealden Beds, and the interest of the 
specimen now described is chiefly in its size. It may be known as 
Hemiomus major, gen. et sp. nov., in reference to the absence of 
ossification of the hinder aspect of the distal end of the bone, and. 
as indicative of its size. 


[For the Discussion on this paper, see p. 418.] 


416 PROF. H. G, SEELEY ON EVIDENCE OF A BIRD FRoM [Aug. 1899, 


27. On Evivence of a Brrv from the Wratpen Beps of Ansty Lang, 
near CuckFiELD. By Prof. H. G. Sprrey, F.R.S., F.L.S., F.G.S. 
(Read May 24th, 1899.) 


On a visit to Ansty Cross made by the London Geological Field 
Class, I identified a fragment of bone found embedded in the sand- 
stone by Mr. Neville Jones, as probably the distal end of the femur 
of a bird. It was unfortunately extracted from the matrix, and 
subsequently it was left with me for determination. 

The fragment is ? inch long, compressed from back to front, with 
the bone of the shaft thick and enclosing a small medullary cavity. 
At the proximal fracture the bone is 7 inch wide and } inch thick. 
The width at the distal articulation is 4, inch; and the bone 
becomes bent downward and is thickened inferiorly with develop- 
ment of the condyles, though not to quite the extent seen in most 
existing birds. 

The inner side of the bone is narrower than the outer side. As 
the narrow, rounded inner side of the shaft is prolonged distally, 
it becomes flattened, with a slight median convexity; and is 
thickened, partly owing to a superior marginal ridge, and partly 
in consequence of the thickening of the inner condyle. 

The outer side of the bone is thicker, but not so thick as in the 
femur of Hnaliornis ; nor is the external side flattened so much as 
in that genus. An inflation on its middle part defines a superior 
lateral oblique area, below which there is an imperfect groove. This 
defines a thickening of the outer side of the large external condyle, 
quite on the type of Hnaliornis and Colymbus. 

The external condyle is not only larger and deeper, but is more 
prolonged distally. This is perhaps the most distinctive avian 
‘character ; for though in a Dinosaur the inner side of the distal end 
may be flattened, and the outer side angular, it is the inner condyle 
which is usually the larger. And in no case is the external condyle 
produced distally, except apparently in Hypsilophodon, exceptionally 
according to Hulke’s figure. The condyles are well rounded. The 
external surface of the bone, in consequence of the size of the outer 
condyle, has the appearance of extending obliquely outward, making 
a slight approximation to the condition seen in Colymbus and its 
allies. 

The superior surface of the bone does not widen so rapidly at the 
distal articulation as in Hnaliornis ; but there is a similar shallow 
groove on it which widens to the distal extremity, extending later- 
ally over the condyles. The groove becomes prolonged into the 
notch between the condyles on the distal extremity of the bone. 

The inferior surface of the shaft is concave in length and also 
from side to side, being bounded laterally by shghtly-developed 
rounded ridges, which extend proximally from the condyles. The 
notch between the condyles is narrower and deeper than in Fnali- 
ornis, owing chiefly to the well-rounded form of the condylar surfaces 
on the under side of the bone. 


Woltics.| THE WEALDEN BEDS OF ANSTY LANE. 417 


Colymbus is the only existing bird to which the fossil makes any 
approximation ; but the resemblance i is distant, and is not suggestive 
of near affinity. It is interesting that the Cretaceous birds show 
so marked an affinity with that type. 

The resemblances of the dinosaurian and crocodilian femora 
with this type are such that almost every individual feature of the 


Left femur of bird (?): distal end, twice nat. size. 


# B. Seeley del. 


A = Posterior aspect ; B = Anterior aspect ; C = Distal articular surface ; 
D = External aspect; H = Internal aspect. 


bone can be paralleled in some fossil referable to those groups. 
No British dinosaurs, however, are known of such small size, or 
with the shaft of the bone so compressed, with the condyles at 
once so well rounded and limited to the inferior surface. Nor am I 
aware of a dinosaur in which the shaft of the bone widens externally 
in harmony with the condyle pone distally. Eyen in Hyps:- 


Q.J.G.8. No. 219. 2R 


418 WEALDEN BIRD AND MAMMAL. [Aug. 1899, 


lophodon,' in which the external side of the bone is deeper and 
produced distally in the condyle, there is practically a flat external 
surface to the bone and no inferior development to the condyles. 
The character of the fossil which, in view of its partial approxi- 
mation to Colymbus, might be regarded as least avian, is the deep 
notch between the condyles on the inferior surface, and this some- 
what Iguanodont character is replaced in Hypsilophodon by a broad 
open notch which is much more bird-like. Some of the Crocodilia 
closely approach this femur in the form of the distal end. There 
are many points of resemblance in Crocodilus Spenceri, especially in 
the distal prolongation of the condyle, and the same character is 
seen in Crocodilus sivalensis. But in no known crocodiles, recent or 
fossil, are the inferior condylar surfaces so much developed. The 
femur of Heterosuchus is not known: but it is probably the only 
erocedile which might so approach this type of animal as to suggest 
caution in unqualified acceptance of its avian interpretation. 


DIscussION ON THE TWO FOREGOING PAPERS. 


Mr. E. T. Newron agreed with the Author as to the mammalian 
affinities of the humerus from near Tonbridge, but thought that 
the bone had been much denuded, and that its form indicated a 
late Tertiary or even more modern origin. The characters of the 
fragment of a femur from near Cuckfield seemed to him to point 
rather to crocodilian than avian affinities. 

Mr. R. Lypexxer and Mr. C. W. Anprews also spoke. 

The Avraor said, with reference to the suggestion that the 
mammalian fossil was of Tertiary age, that no generic type had 
been suggested for comparison. He was able to state, after com- 
parison of the specimen with materials in the British Museum, that 
there is no fossil to which it approximates sufficiently to necessitate 
detailed comparison. No such fossil, so far as he was aware, had 
ever been figured. The resemblances are probably closer with 
living than with extinct genera, though the fossil is in some 
respects more generalized than either. 

With regard to the suggestion that the lower borders of the 
olecranon-pit are worn, he drew attention to the fact that the 
character is only an intensification of a feature common in the 
same position in the humerus in antelopes and deer, though not 
limited to those groups. There is in the dry skeleton an ovate 
vacuity between the hinder distal end of the humerus and the 
olecranon-process of the ulna, which varies in size in different 
genera: in this fossil it appears to have been unusually large. 
The surface in question on this humerus shows no sign of wear, for 
it 1s concave, and corresponds with the recent specimens in con- 
dition. He had nothing to add concerning the Cuckfield bone, as 
the views which had been suggested are stated in the paper. 


1 Hulke, Phil. Trans. Roy. Soc. vol. clxxiii (1882) pl. xxviii. 


Vola55-] VERTEBRATE FAUNA OF THE IGHTHAM FISSURE. 419 


28. AppitionaL Norss on the VERTEBRATE Fauna of the RocK-FIssURE 
at IentHam (Kent). By EK. T. Newron, Esq., F.R.S., F.G.S. 
(Read June 21st, 1899.) 


[Puarse XXVITT.] 


Tue results obtained by Mr. Lewis Abbott’s exploration of the 
Ightham rock-fissure were published by the Geological Society in 
1894,’ but the investigation was continued by that gentleman with 
his usual energy, and many additional specimens were obtained, for 
the most part representing species already recorded. Before the end 
of 1896, however, five forms, new to the deposit, had been recognized, 
and were mentioned in Sir A. Geikie’s Annual Report of the 
Geological Survey for that year (published 1897, p. 88). These 
forms were a large bat (probably Vespertilio Bechsteint), the shoveller- 
duck, and some small passerine birds, closely allied to, if not identical 
with, the red-backed shrike, the chaffinch, and the hedge-sparrow. 
Subsequently remains of polecat, otter (?), and swallow were found. 

Since Mr. Lewis Abbott’s departure from Sevenoaks, the work of 
collecting from the Ightham fissure has been successfully carried on 
by Mr. Frank Corner and Mr. A. 8. Kennard. The many specimens 
obtained have passed through my hands, and certain forms, new to 
this fissure, have been recognized, while among the numerous 
examples of species already recorded there were some which 
previously had been but sparsely represented. 

In the following pages, mention will be made of all the forms 
new to the fissure that have been found since 1894, and notes 
will be given on certain other species, concerning which additional 
and important information has been obtained. 

Nearly all the remains now to be recorded are those of species 
still living in the neighbourhood, and they give a modern aspect to 
the collection. It must be remembered, however, that these modern 
types are mixed with forms not known to have lived in this country 
since Pleistocene times. Even if some of these remains found their 
way into the fissure at a comparatively recent period, it is evident 
that the climate of Kent must have been very different from what 
it is now when the Arctic and Norwegian lemmings, together with 
the Arctic fox and Siberian vole, were living in the neighbourhood. 


1. AnserR, sp. (Goose.) 


A left humerus, wanting the proximal end, is without doubt to be 
referred to this genus and probably to the common form, Anser 
cinereus, with which it agrees in form and size; but as there are 
other species of about the same size, such as the pink-footed and 
white-fronted geese, its species cannot be determined with certainty. 

This bone was not found in the main fissure, but in the collateral 
one from which the large wolf-bones were obtained (p. 427). 


1 Quart. Journ. Geol. Soe. vol. 1, pp. 171 & 188. 
Ze 2 


420 MR, E. T. NEWTON ON THE VERTEBRATE FAUNA ([ Aug. 1899, 


2. Spatuta ctypeata, Linn. (Shoveller Duck.) 


The specimen referred to this species is a humerus, obtained 
by Mr. Lewis Abbott, which agrees so closely with the same bone 
in the recent species as to leave little doubt as to its identity. 


3. Fatco perecrinvs, Tunstall. (Peregrine Falcon.) 


A perfect tarso-metatarsus of a raptorial bird obtained by 
Mr. Frank Corner agrees with the corresponding bone of the 
peregrine falcon, and is unlike that of any other bird with which 
I have been able to compare it. Indeed, I have no doubt as to its. 
representing this species, which is a widely-distributed form at the 
present day, extending from the Mediterranean Sea to Novaya 
Zemlya and Greenland. 


4, Hirvunpo rustica, Linn. (Swallow.) 


A well-preserved humerus of this species, found by Mr. Lewis: 
Abbott, enables us without doubt to add the swallow to the fauna of 
the Ightham fissure. 


5. Lantus cotturio (?), Linn. (Red-backed Shrike.) 
6. Frineria caress (?), Linn. (Chaffinch.) 

7. AccENTOR mopuLARIs (?), Linn. (Hedge-sparrow.) 
8. Turpus mervta (?), Linn. (Blackbird.) 


Each of these four passerine birds is apparently represented by 
one or two limb-bones, but the identifications are by no means 
certain. 


9. VespERtTItio BecusteIni (?), Leisler (or V. murinvs). 


Besides the lower jaw obtained by Mr. Lewis Abbott, and already 
referred to, a number of other specimens have now been found.. 
Among these are the skull, lower jaw, humerus, femur, and other 
parts of one skeleton. The dentition of this specimen is that 
of the genus Vespertilio. The skull is longer and proportionately 
narrower than in V. Nattereri, and the limb-bones are longer. It. 
is almost certain that these remains belong to V. Bechsteint, or it 
may be V. murinus. Other skulls, lower jaws, and: limb-bones- 
agreeing with these in form and size are referred to the same: 
species. 


10. Vespertitio Davsentont (?), Leisler. 


Portions of another Vespertilio-skeleton indicate a species smaller 
than V. Nattereri, and the skull agrees so closely in size and form 
with that of V. Daubentoni, that it is provisionally regarded as a 
representative of that species; but possibly it may belong to 

_V. mystacinus, which is of nearly the same size and of which I 
have no skeleton for comparison. A second skull and some limb-- 
bones are referred to this species. ; 


Vol. 55.] OF THE ROCK-FISSURE AT IGHTHAM. 421 


11. Lepvs varrasiuis, Pallas. 


In my earlier paper the remains of hares from the Ightham fissure 
were referred to the common European hare Lepus timidus (=L. 
europeus), on account of the breadth of the iliac bones and the 
general stoutness of the limb-bones. Many additional specimens 
have now been obtained, showing similar robust proportions, and 
among them the maxille of two individuals which exhibit dental 
characters more in agreement with those of ZL. variabilis than with 
those of Z. europeus. The robustness of the limb-bones still seems 
to agree best with the proportions found in the last-named species, 
even when allowance is made for the variations to be seen among 
recent forms. The peculiarities of the teeth, however, have led me 
to re-examine the specimens, and to modify my opinion as to the 
affinities of some of the remains of these fossil hares. 

A pair of maxille and a single right maxilla are proved to belong 
to hares and not to rabbits, by the wide posterior palatine vacuity 
and by the small extent to which the palatine bones enter into the 
formation of the transpalatine bar. 

The anterior cheek-tooth of both these specimens shows the deep 
notch on the inner side, like that found in Lepus variabilis but not 
in L. europeus. The upper incisors of L. europeus have more 
strongly-marked grooves than those of ZL. varzabilis, and they are 
not quite so near the inner margins. Two upper incisors from 
the Ightham fissure resemble in these respects the incisors of 
L. variabilis. 

There are some points in the structure of the limb-bones of hares 
to which attention must be directed. The femur of L. europaeus 
has the ridge for the insertion of the psoas and iliacus-muscles, 
which is seen on the hinder aspect of the bone a little below the 
articular head, very oblique and extending only a short way beyond 
the level of the lesser trochanter; in Z. variabilis this ridge is less 
oblique, and it extends farther down the shaft. The head of the 
humerus of L. ewropeus, when viewed from above, is found to be 
rounder than in ZL, variabilis, being in the latter more elongated 
from before backward and tending to become parallel-sided. The 
ulna of LZ. europeus is broader and flatter at about the middle of its 
length than is the case with the same part in L. variabilis. Most 
of the femora, humeri, and ulne of the hares from the fissure agree 
in these particulars with Z. variabilis rather than with L. europaeus ; 
and as the dental characters point in the same direction, I am 
inclined to refer the greater number of these remains to L. variabilis, 
notwithstanding the robustness of the bones, which seemed at first 
to favour their reference to the common European form. 

The bones of large hares from the Somerset caves described by 
Mr. W. A. Sanford’ under the name of ZL. diluvianus, and those 
from Zuzlawitz described by Dr. Woldiich’ as L. variabilis, seem to 
be specifically identical with those from Ightham. I prefer to 


1 Quart. Journ. Geol. Soc. vol. xxvi (1870) p. 126. 
2 Sitzungsb. d. k. Akad. d. Wissensch. Wien, vol. Ixxxii, Abth. i (1880) p. 11. 


422 MR. E. T. NEWTON ON THE VERTEBRATE FAUNA  [ Aug. 1899, 


follow the last-named author in regarding ZL. diluvianus as 
synonym of L. variabilis. 

The name of L. variabilis is used in this paper to indicate the 
Northern species of hare, which was no doubt the form described 
by Linneeus under the name of ZL. timidus ; but the adoption of the 
‘latter name, which has for so iong been used to indicate another 
species, would only lead to endless confusion. 


12. Lepvs cunicutus, Linn. (Rabbit.) 


The presence of the bones of the rabbit was noted in my previous 
paper’; we now have a large maxilla with teeth and the fore part 
of the palate. The narrowness of the posterior palatine vacuity, 
and the large part which the palatine bone takes in the formation 
of the transpalatine bar, as well as the folding of the enamel of 
the anterior cheek-tooth, show that this specimen belongs to a 
rabbit and not to a hare. The condition of preservation of this 
maxilla is the same as that of most of the bones from the Ightham 
fissure. ; 


13, SPERMOPHILUS ERYTHROGENOIDES, Falconer. (PJ. XXVIII, figs.. 
7-10.) 

Although several fragments of this genus had been found when 
my earlier paper was published, none of them were sufficiently 
perfect for specific determination. Mr. Frank Corner and Mr. Ken- 
nard have now found a perfect right ramus of a lower jaw with all 
the teeth in place, and a large portion of a skull retaining on one 
side its broad jugal arch: the maxillary process of this arch being 
much expanded. A humerus, a scapula, and a fibula have also 
been found. 

The lower-jaw ramus agrees with Falconer’s? figures of Spermo- 
philus erythrogenoides and also with the lower jaws of Spermophilus 
from Erith, obtained by Mr. F. C. J. Spurrell and presented by him 
to the Museum of Practical Geology; but none of the Pleistocene 
specimens that I have had the opportunity of examining are so perfect 
as this one from the Ightham fissure. When viewed from the side, 
the proportions of the articular, coronoid, and angular processes are 
the same as in Falconer’s fig. 2, and the obliquity of the articular 
surface is likewise similar. The angular process is directed outwards, 
and the lower and hinder part of the well-defined masseter-disc is 
turned so strongly inward as to become almost horizontal. The 
inward turning of the lower margin is not shown in Falconer’s 
figures, but that is probably due to imperfection in this region, 
as it is a characteristic of the living species. 

The appended measurements of the _Ightham ramus may be com- 
pared with those given by Falconer of a specimen from the Mendip 
Hills (Jac. supra cit.) and by Nehring * of an example at Jena. 


? Quart. Journ. Geol. Soe. vol. 1 (1894) p. 194. 
2 * Paleont. Memoirs,’ vol. ii (1868) pl. xxxv, figs. 1-3. 
3 Neues Jahrb. vol. ii (1880) p. 121. 


Volo 55. | OF THE ROCK-FISSURE AT IGHTHAM. 423 


- 35 a S 
Measurements of Spermophilus- a = q g 38 £4 
Skulls (in millimetres). 25g est Oa MGS A OMS = 
aoe | ee 88(te e 
= aS 2) | & 
OSs aa 2 
Front of premaxilla to hinder edge oi 
[Oz Te ELE IIS ois se Ss Rea men of SS 2 8 50:0 | 45-0 49:0 54:0 
Front of premaxilla to hinder edge of 
PIC SAUS eS Selo duiaeiedannieacle « ovine semen ome AiO. |. 200 21:0 
Front of premaxilla to hinder edge of 
PMEMMCH SIMO ee oe ccne es aces ona esermeededees 315 | 28:0 29:0 
Front of premaxilla to anterior cheek- 
ETON PRE PO's soos onicienceddg eee aoe 160} 145 15°5 
Greatest width across jugal arch ............ 380 | 340 32:0 | 38:0 
a is Bu DRAIM-CaSb..:caaarestes 250 22°0 21-4 
Least interorbital width of frontals ......... 10:0 9:0 11-2 10:0 
Orbital diameter, postfrontal to lachrymal .| 15:0 145 14:0 
Length of premaxilla in mid-line of palate.| 9:5 9°0 9°5 
. maxilla % a: 14:0 13:0 12:0 
% palatine ss és 8:0 6:0 é5 
Width of palate outside alveoli ............ EO.) A} 150 
Length of alveoli of five cheek-teeth......... 12:0 11-0 12:0 13:0 
Width across both palatine notches ......... 40 | 236 45 
~235 “ - 
fs Sis ee. ~§ 
Measurements of Lower Jaws | 2 (S358) 38 | 54) Zs 
- sarc a} dS = 8s = oO fs 
(in millimetres). S88 8| a8 | Ss | ee 
QO) St S55) | ae -Z © 
WSS GS [2° | ae 
Back of articular condyle to hinder border 
BECO 28 occas 45-5 «ne os oceanaewanincoseeen 34:0} 31:0 | 32:0 | 35-0 
Back of articular condyle to front border 
CR URUTCISE (8) Ara oo duoc sa vca nscmteeeeeemnes 35°5| 32°5 | 33:0 34°5 
Posterior angle to front border of incisor...} 35°5} 32°5 | 33-0 34:5 
Length occupied by four cheek-teeth ...... EVO 96-102. |) 120; hae 
Hinder border of incisor to back of last 
(IDG iaaet oA ae Seo eee meP Dest Serhoe ae 19:0) 170 | 18°5 
ihienetin of diasteme ........../icsisaseeen eorsaaes 8:0| 7:5 85 75 
Length from front of masseter-dise to 
indenture between angle and condyle ...}185) 17:0 | 17-0 18:0 


1 In Falconer’s figure these teeth measure 11:5 millimetres. 


The skull wants the right jugal arch, the left premaxilla, the 
occiput and all the teeth; but there is still sufficient left to 
trace the outline of the skull, and especially the form of the 
broad jugal arch. The entire skull is broad and depressed ; 
the orbits are large ; the cranium is broad, especially in its hinder 
part, and the surface of the bone is strongly pitted. There 
is a short, slight median crest at the hinder part of the parietals ; 


424 MR. E, T. NEWTON ON THE VERTEBRATE FAUNA [| Aug. 1899, 


from this the edges of the muscular attachments diverge, and, 
passing forward, curve suddenly outward to end in the post-orbital 
processes of the frontals, which are prominent and directed some- 
what backward. The interorbital space is smooth and depressed. 
The antorbital process of each frontal is broad, and is continued 
outward by the maxilla: this, descending in front of and below 
the orbit, forms the extremely broad plate which is a characteristic 
feature of this skull. The jugal bone extends outward beyond the 
maxilla, and passing backward joins the process of the squamosal, 
the anterior extremity of the latter marking the greater width of 
the skull. The premaxilla is comparatively short. 

The palate is almost perfect on the right side; all the alveoli are 
preserved, showing that the anterior cheek-tooth had one large fang, 
while the other four teeth had each three fangs—a large inner one 
(not so large as that of the front cheek-tooth), and two much 
smaller outer fangs. The right premaxillary foramen is a slit 
occupying the hinder. half of the bone, and indenting the front of 
the maxilla. There is a median spine at the hinder border of the 
palatine bones. 3 

A comparison with the series of skulls in the Natural History 
Museum at South Kensington shows that this Ightham Spermophilus 
is nearly related to, if not identical with, the Siberian Sp. erythro- 
genys. The lower jaw, as we have seen, agrees with that from the 
Mendips, which Dr. Falconer also considered most closely related to 
the same species, and called Sp. erythrogenoides. One peculiarity 
of the Ightham skull is its great width, chiefly due to the wide- 
spreading jugal arch; and this feature, among skulls of corre- 
sponding size, is most nearly represented by So: erythrogenys. . 
None of the skulls of Sp. altaicus (=Sp. Eversmannt) in the Natural 
History Museum are so wide across the jugals, but they are wider 
between the orbits. In other respects there is much resemblance 
between the last-named species and the Ightham Spermophilus. 
The want of recent skeletons and the imperfections of the fossils 
prevent a definite reference of this Spermophilus to Sp. erythro- 
genys ; and it will be best, therefore, to follow Dr. Falconer and to 
include it with the Mendip specimens in his Sp. erythrogenoides. 
I should also refer to the same species the Spermophilus-remains 
from the Brick-earth of Crayford and Erith. 

The skulls from the Fisherton Gravels, preserved in Dr. Black- 
more’s Museum at Salisbury, are much like that from Ightham, 
and possibly may belong to the same species, for there is a 
similar expansion of the jugal arch, and a like narrowness of the 
interorbital region. However, points of difference are to be seen ; 
and the lower jaw’ has a more slender process for the articular 
condyle. 


14. Mus Lewrs1, Newton (=M. Axssorri, Newton). 


Since my previous paper was published, Mr. Barrett-Hamilton, 
who has been working on the Mice of St. Kilda,” called my attention 


? See Falconer, ‘ Paleeont. Mem,’ yol. ii (1868) pl. xxxv, fig. 10. 
2 Proc. Zool. Soc. 1899, p. 77. 


Vol. 55. ] OF THE ROCK-FISSURE AT IGHTHAM. 425 


to the use of the specific name of M. Abbotti by Mr. Waterhouse * 
for a small mouse from Trebizond, and courteously suggested that I 
should give some other name to this fossil; this I have done in a 
note to the Zoological Society,” naming it Mus Lewisi, in order that 
it may still be associated with its discoverer, Mr. Lewis Abbott. 
The species is now represented by several additional examples of 
lower-jaw rami with teeth. 


15. Microrvs arvatis, Pallas. 


The occurrence of this species is confirmed by the discovery of 
several portions of one skeleton. The number of angles to the 
front lower cheek-teeth shows that it must belong to either 
M., agrestis or M. arvalhs ; and the presence of only five angles to 
the second upper cheek-tooth prevents its reference to the first of 
‘these. 


16. Microrus nivatis (?), Martins. (Alpine Vole.) 


The front lower cheek-tooth of this species is not always to be 
clearly distinguished from extreme forms of M. glareolus; but 
among the very many examples of the latter species which have 
been obtained by all the collectors from the Ightham fissure, there 
are several which have the inner part of the anterior prism well- 
developed, so that five inner and four outer angles may be counted. 
It seems highly probable, therefore, that these are the remains of 
Microtus nivalis. 


17. Musreza vutearis, Briss. (Weasel.) 


In my earlier paper * some very small bones were recorded as the 
variety minuta of this species, and other equally small bones have 
since been obtained; but in addition to these we now have skulls 
and limb-bones belonging to several individuals that correspond in 
size with the common weasel. It must now, therefore, be included 
in this fauna. 


18. Musreta putorius, Linn. (Polecat.) 


Besides the specimens found by Mr. Lewis Abbott, skulls and a 
number of limb-bones have been secured by Mr. Frank Corner and 
Mr. A. S. Kennard, which correspond in all particulars with those 
-of the normal polecat, and undoubtedly represent that species. 


19. Musreta rosusta, Newton. (Giant Polecat.) (Pl. XXVIII, 
figs. 1-6.) 

In my earlier paper a humerus and some other bones of a large 
Mustela were made the type of this species. Since then, additional 
bones have been found which add much to our knowledge of this 
form. Mr. Frank Corner and Mr. Kennard obtained from the 
collateral fissure, which they call the ‘small horse fissure,’ a 
humerus even larger than that originally figured, as well as a 


1 Proe. Zool. Soc. 1880, p. 61. 2 Ibid. 1899, p. 381. 
3 Quart. Journ. Geol. Soc. vol. 1 (1894) p. 201. 


426 MR. E. T. NEWTON ON THE VERTEBRATE FAUNA [Aug. 1899,. 


femur, tibia, and fibula of corresponding size. The most important 
specimen, however, is part of a skull and lower jaw with nearly 
all the teeth in place, which was acquired by Col. Underwood, of 
Sevenoaks, and given by him to the late Miss Bevington, by whom 
it was generously presented to the Museum of Practical Geology. 

The similarity of the type-humerus to that of a polecat, rather 
than to that of a marten, was commented on in my earlier paper, 
and all the additional specimens show a like affinity, being more 
robust than the limb-bones of the last-named species, although not 
attaining the same length. 

The humerus, like that first described, is from the left side ; 
it consequently represents a second individual, and, being rather 
longer (57°5 mm.), indicates a somewhat larger animal. The femur 
is 64 mm. long, and its condyles are 13 mm. wide. The tibia is. 
67 mm. long, and its proximal end is 12°5 mm. wide; seen from 
the side this bone is more curved than the tibia of the marten or 
polecat with which I have had the opportunity of comparing it. 

The skull, so far as preserved, agrees with that of the polecat,. 
and not with the marten; the dental formula being :— 


Phyl BL 1 

in. 5, C. 7, pM. 5, M. 5. 
The front part of the skull is well-preserved ; but the upper and. 
hinder parts of the brain-case are wanting. On the left side 
the orbit is complete, and the jugal arch, with a slight imper- 
fection, is continued into the squamosal and auditory region; the 
articulation for the lower jaw, the external auditory meatus, and 
the tympanic bulla are preserved. The angle formed by the two 
rows of cheek-teeth is wider than in the marten, and corresponds: 
with what is found in the polecat. 

The broken condition of this skull prevents some important 
measurements from being taken; but the following show that in 
all particulars this skull is bigger than the largest of the gigantic 
forms measured by Hensel.’ 


Measurements of Skull and Lower Jaw (in millimetres). 


ean ea Hensel’s | Hensel’s | Woldrieh’s 
= ‘largest 9. | medium. largest. 

Basal denpehis...¢ sconce eecene= ?69°5 67°3 58:1 61+ 
Width across jugal arches ...... 51:0 45-4 382 44 
Width outside upper canines...) °20°5 17°5 15-1 175 
Tengthy of palate v...the. teens 30'0 33°] 28°7 

3 upper cheek-teeth ... 22°0 20°4 18-2 

hi lower-jaw ramus ... 46:0 43-0 36°7 

* jo. 5p ROBUE Reece 27°5 25°7 23'0 

ooh, Se eee. 9-0 8:7 8:1 

in upper pmsl Aes eee 85 8:3 75 


1 «Craniologische Studien,’ Nova Acta Acad. Leop.-Carol. Nat. Cur. vol. xlii: 
(1881) p. 125. 


Vol. 55. | OF THE ROCK-FISSURE AT IGHTHAM. 427 


Both rami of the mandible are preserved, and only two of the 
tubercular teeth are wanting. All the teeth are strongly sculptured, 
especially the canines, which also possess a very prominent inner 
cingulum. 

There is no evidence that the remains above noticed belonged to 
one animal; indeed, judging from the proportionate size of the 
skull and limb-bones in recent specimens of the polecat, the humerus 
(57°5 mm.) would correspond with a skull having a basal length 
of 75 mm., which would be considerably larger than that above 
described. On the other hand, there is every probability that the 
skull and limb-bones represent but one species. 

The discovery of this large skull has supplied data for the com- 
parison of M. robusta with the skulls described by Hensel (op. cit.), 
Cornalia,’ and Woldiich?; and there is no doubt as to its agreement 
with the skulls which these authors figure as large forms of the 
polecat. The present specimen is distinctly larger than the biggest 
of Hensel’s or either of the fossil specimens, and the limb-bones 
almost certainly represent a still larger animal. Under these 
circumstances, and as the name of M. robusta has already been 
used, it may perhaps be allowed to remain, if only as a varietal 
designation for these giant British forms, until they are found to 
be the same species as that to which Meyer gave the name, of 
M. antiqua. 3 

Among the remains of mammals recently recorded by MM. Mar- 
cellin Boule & Gustave Chauvet’ from an ossiferous fissure in 
Charente (France), two crania of Mustela putorius are mentioned 
as notably larger than those of the modern polecat; in all proba- 
bility these are representatives of VM. robusta. 


20. Canis Lupus (?), Linn. (Wolf.) 


Several parts of the skeleton of a large canine animal have been 
recovered by Mr. Frank Corner & Mr. A. 8. Kennard from a col- 
lateral fissure joining the original one at Ightham. These remains. 
include parts of the skull and lower jaw as well as limb-bones and 
vertebre. The close resemblance between the bones of a wolf and 
those of a dog of similar size prevents as positive a reterence of these 
remains to Canis lupus as could be wished, but there is every 
probability that they represent a wolf of large size. 

The skull is too fragmentary to allow of any useful measurements: 
being made, but the following dimensions of other parts of the 
skeleton will be advantageousjfor comparison :— 


* ‘Monogr. des Mamm. foss. de Lombardie,’ in Pal. Lomb. ed. Stoppani, 
ser. 2 (1870) p. 33 & pl. xi. 

? Sitzb. k. Akad. d. Wissensch. Wien, vol. Ixxxii, Abth. i (1880) p. 32. 

$ Comptes-rendus Acad. Sci. Paris, vol. exxviii (1899) p. 1188. 


428 MR. E, T. NEWTON ON THE VERTEBRATE FAUNA [Aug. 1899, 


Measurements of Canis lupus (?) from Ightham. 


Millimetres. 
Length of right ramus of lower jaw from angle to hinder 
border:of camimeraliveolus\ jc: .cu ssn eeecaeee tree ee. teeeee ee 154-0 
Length of hinder border of canine alveolus to hinder border 
of lastsmolatvalyeolus: 85.11% .uc asst ade daauneaeieshseeeee esenalctes 101:0 
Depth of ramus at hinder end of molar 1 .......:....se»cscsseves 31:0 
3 betweensona. 22) aia Used! Pw nie cee cuderioe vere cea eee 24:0 
Height of coronoid process from hase of angular process ...... 63:0 
Teng iln Of M@larL | Roo acusencceearssrecs om anbee dt cas cretneceaewcer cane _ 290 
TVEKHERS | MIATA LI pean hae. toate cede ae «otro aa oe Sta 11:2 
Tengtl of femal? sassecarieebeaeie fidels tycpsodtmeseshasneceesee satan 2120 
BURL Whines oe Pepeetne c. teee dee oa ate a ee 215-0 
a humerus, distal condyle to angle of deltoid crest ... 127-0 
iA » calculated from last measurement ......... 198-0 


21. Feuis carus, Linn, (Cat.) 


A femur and a canine tooth represent this species, but there is 
no proof that they are parts of a wild animal, and they may be a 
comparatively modern introduction. 


22. Lurra vuteaRis(?), Linn. (Otter.) 


Some bones of a young animal, without their epiphyses, were 
obtained by Mr. Lewis Abbott, and these may perhaps belong to a 
very young otter; but they are too embryonic to show their dis- 
tinctive characters. 


23. Mutus taxus, Bodd. (Badger.) 


The presence of the badger in these deposits has been confirmed 
by the finding of a skull and other remains. 


MM. Marcellin Boule & Gustave Chauvet have been good 
enough to send me an account of their researches in the interesting 
ossiferous fissure at Champs-Gaillards (Chateauneuf-sur-Charente),! 
from which they have obtained a series of vertebrate remains, very 
similar to those from the Ightham fissure, including several northern 
species which give an arctic character to the fauna, and indicate, 
in no uncertain way, the influence of the extreme cold of the Pleisto- 
cene period far southward in France. 


1 «Sur l’Existence d’une Faune d’Animaux arctiques dans la Charente 4 
V’Epoque quaternaire,’ Comptes-rendus Acad. Sci. Paris, vol. cxxviii (1899) 
p. 1188. 


Quart. Journ. Geol. Soc. Vol. LV. PlLAOVvit= 


- imp. 


Mantern Bros 


ith. 


AT. Hollieck del.et 


Ie MUSTE LAC. 7-10, SP EGGS aves 


POM LGET HAE 


Vol. 55-1 


OF THE ROCK-FISSURE AT IGHTHAM. 


429) 


The following is a list of the species found in the Ightham fissure 
since the publication of my earlier paper in 1894 :— 


Anser sp. (Goose.) 

Spatula clypeata, Linn. (Shoveller 
Duck.) 

Falco peregrinus, Tunstall. (Pere- 
grine Falcon.) 

Hirundo rustica, Linn. (Swallow.) 

Lanius collurio (?), Linn. (Red- 


backed Shrike.) 
Fringilla celebs(2), Linn. (Chaffinch.) 
Accentor modularis (?), Linn. (Hedge- 
Sparrow.) 
Turdusmerula (2), Linu. (Blackbird.) 


Vespertilio Daubentoni (?), Leisler. 
Lepus variabilis, Pallas. 
Spermophilus erythrogenotdes, Falc. 
Mus Lewisi, Newton (=M. Abdbotie, 
Newton). 
Microtus nivalis (2), Martins. (Alpine 
Vole.) 
Mustela putorius, Linn. (Polecat.) 
» vulgaris, Briss. (Weasel.) 
Canis lupus, Linn. (Wolf.) 
Felis catus, Linn. (Cat.) 
Lutra vulgaris (?), Linn. 


(Otter.) 


Vespertilio Bechsteini (?), Leisler (or 
V. murinus), 


EXPLANATION OF PLATE XXVIII. 
Specimens from the Ossiferous Fissure at Ightham. 


[All the figures are of the natural size, except fig. 10.] 


Figs. 1-6. Mustela robusta, Newton. 
Fig. 1. 


Skull viewed fiom the left side, outline of brain-case restored. Presented 
to the Museum of Practical Geology by the late Miss M. Bevington. 

. Same specimen, palatal view. 

be left ramus of mandible. 

. Left humerus, front view. 

Right femur, front view. 

. Right tibia, inner side, to show curvature. The three limb-bones were 

obtained by Messrs. Frank Corner & A. S. Kennard. 


> OU o9 bo 


Figs. 7-10. Spermophilus erythrogenoides, Falconer. 
[Specimens obtained by Messrs. Frank Corner & A. S. Kennard.] 


Fig. 7. Skull viewed from above, outline restored. 

8. Same specimen, side view, front part drawn from the right side, hinder 
part restored in outline. 

9. Right ramus of mandible, outer surface. 
and appears like a left ramus. 

10. Four right lower cheek-teeth, enlarged (x2), and seen from above. 

The front tooth is above the numeral 10; the second tooth is 
imperfect on the inner side. 


This figure has been reversed, 


430 MR, J. PARKINSON ON AN INTRUSION OF GRANITE [ Aug. 1899, 


29. On an Inrrusion of Granite into DiaBase at Soret Porn 
(NortHERN Jerszy). By Jonn Parxinson, Esq., F.G.S. (Read 
June 7th, 1899.) 

[Puares XXIX & XXX.} 


ConrTeEnts. 

Page 
Ta Introduetion:  gcaye tec. .5 lets: | {atdinncasikedncn sceqeessce este 430 
Tie, Pie Gramitee  wWengeenaga-acoctets sat nace ae ueeeem ent a. ah aok ek ee 432 
LIT, “Phe Diabase. sant. sch ouleerssinc dics sweteate tt. ince A 434 
TY. Rocks contaimnge Derived Material ..........<.cese>.«.resceo-ane seen 435 
V. Junction between the Granite and the Diabase ..................... 440 

VI. Comparison of the Phenomena with those observed in other 
DsGrie be: eles) vosere ts othe t acai s mene taawaupee ace sande eee, ee 444 


I. Iyrropvcrion, 


PrRomInENT among the many points of interest which the igneous rocks 
of the Channel Islands offer for study are those that arise from the 
intrusion of one rock into another. In Sark the relations of the aplite 
to the pre-existing hornblendite are well known through the work of 
Prof. Bonney & the Rev. Edwin Hill’; in Guernsey the latter 
Author” has touched briefly on the relations, apparently of rather 
unusual character, existing between a granite and a dioritic rock ; in 
Jersey M. Noury, in his work upon that island,® has remarked upon 
the complete penetration in more than one place of a ‘ diorite’ by a 
granite. It is to one of these intrusions, that of the north coast, 
that the present communication relates. 

In many respects both the rocks and the locality are favourable 
for study. The contrast presented by the brick-red granite so poor 
in ferromagnesian constituents as to be practically an aplite, and 
the dark basic rock into which it intrudes, is sufficiently striking 
to render the broad facts apparent almost at a glance. The magni- 
ficent cliffs, under favourable circumstances of tide and weather, 
afford ample opportunities for the study of these relations in greater 
detail. Anyone, walking westward from St. John’s, in the centre 
and north of the island, and taking the road to Les Meuriers, will 
find, by turning to the right when reaching the sea and keeping 
along the edge of the cliff, the relations of the two rocks displayed 
as finely as he can desire. Looking down into one of the numerous 
little bays which indent the coast, veins of red granite can be seen 
piercing and shattering the dark rock. Sometimes they evidently 
proceed from a larger mass of granite, which occupies for a short 
distance the whole cliff-face; more often the younger rock forms 
the outlying shelving masses, seen at their best when left bare by 
the falling tide; but the constant alternation of the two rocks from 
the edge of the sea to the top of the cliff is the most marked 


? Quart. Journ. Geol. Soc. vol. xlviii (1892) p. 122. 
2 sid. vol. x1 (1884) p. 404. 
> *Géologie de Jersey,’ 1886, p. 22. 


Vol. 55.] INTO DIABASE AT SOREL POINT (NORTHERN JERSEY). 431 


feature, and one which shows how complete is the penetration 
effected by the granite. The frequent occurrence of large and 
small fragments of the basic rock split off and isolated in the 
granite indicates this even more obviously ; sometimes these are 
great angular blocks most clearly seen from a distance, at others 
innumerable small chips, fully appreciated only when close at hand. 

As the state of an igneous rock at the time of its intrusion as 
well as the circumstances under which this intrusion was carried 
out are of some interest, one locality, Sorel Point, will be described 
as throwing some light on these matters. From a little distance 
the rock appears to be an uniform red granite, in which lie a few 
elongated fragments of the basic rock from about 10 feet long down- 
ward. A rather closer view, however, shows the acid rock to exist 
in two forms: the first, a brick-red aplite, smooth on its weathered 
surface, fairly coarse, and with conspicuous quartz-grains; the second, 
less markedly red, and apparently a coarser rock with rather large 
felspars standing out on its rough weathered surface. The upper 
part of the section consists of the so-called ‘ diorite,’ and into this 
the porphyritic granite thrusts wedge-like tongues looking like 
waves frozen in place. Here and there the more central part of 
these tongues consists of the red variety, but this is replaced in- 
definitely by the other. On closer examination the conviction 
arises that no great distinction as to age can be made between the 
two varieties of the granite, and it is mereover noticed thut the red 
variety is either free from, or very occasionally contains, fragments of 
the basic rock. On the other hand, in the more porphyritic variety, 
these are constantly to be found: sometimes thickly, sometimes 
sparsely disseminated, frequently appearing as mere shadowy patches. 
The composition varies considerably from point to point, in relation 
with the amount of basic material present. In one case, a softened- 
looking fragment some 6 inches long lay embedded half in the red, 
half in the more basic granite, the two passing one into the other. 
The latter extended round the fragment on the red side as a narrow 
zone; in the same way, when the granite is close to the basic rock, 
a layer of granite, rich in the dark minerals, is interposed between 
the two. In one case this measured about 1 inch across, in another 
3 or4inches. The relations of these two varieties of granite to each 
other are of interest—the more basic or porphyritic forms veins 
and streaks in the red, the two being closely intermingled, yet 
remaining at the same time distinct. At one place this streaking 
took the form of a-V, one limb of which was about 8 feet long by 1 
broad, the other narrower and less clearly defined. In the centre of 
the y was the normal or brick-red granite. At the point of meeting of 
the two limbs the vein thickened out considerably, and here actually 
enclosed rounded fragments, from 3 inches upward—occasionally 
lenticular—of the red granite, seemingly unaltered. In these veins 
or streaks are the usual black patches. 

The occurrence of zones existing between the unaltered red granite 
and the diabase point to merely local absorption along the line ot 
contact. It is, however, difficult to separate these zones from the 


432 MR. J. PARKINSON ON AN INTRUSION OF GRANITE [ Aug. 1899, 


streaks and veins mingled with the more normal rock. A difference 
in general appearance, the porphyritic felspars, and the presence of 
fragments distinguish the former. The clear outlines which usually 
characterize the inclusions of such rocks are frequently softened 
and almost lost, and are replaced by fine-grained patches, 2 or 3 
inches in diameter, containing much quartz, and speckled thickly 
or thinly with the dark minerals. Here and there in these a 
cloud-like streak indicates less complete dissolution. These patches 
pass gradually away into the coarser rock beyond. Here the large 
felspars come in, and occasionally the dark minerals are also larger. 
The texture of some of the better defined veins is much more 
uniform, owing to the fact that the ferromagnesian minerals are evenly 
disseminated, and more in keeping in their characters with the other 
constituents. A thin section shows how close has been the welding ; 
a preponderance of mica and hornblende on one side, with rather 
large felspars, a tendency to a granophyric structure on the other, 
constitute the only differences. It is to be understood that these 
changes in the state of the ferromagnesian minerals are local only. 
The presence of porphyritic felspars in the rock which has done the 
mixing, coupled with their absence in the brick-red granite, which 
moreover contains no inclusions,—these conditions point to an early 
intrusion differing somewhat from that which came after. 

The evidence at hand suggests that the granite-magma was in- 
truded in an order somewhat as follows:—The earliest intrusion, 
characterized by the presence of porphyritic felspars, brecciated the 
diabase, carrying away fragments, some of which were softened and 
permeated by acid material, in greater or less degree. Injections 
often less porphyritic followed, still further softening fragments 
already partially dissolved, and completing the work of mixing 
begun at an earlier period. Here would arise a type of rock in 
which the dark minerals would show no sign of their foreign origin. 
Finally would come the non-porphyritic, granophyric, brick-red 
granite, following the lines taken by the earlier intrusions, scarcely, 
if ever, itself brecciating the diabase, but carrying on with it in its 
course the badly-mixed more basic mass, loaded with fragments, 
which had precededit. This last intrusion, probably viscous, would 
be interstreaked with its predecessors, without the diffusion into 
itself of the basic material which the latter had acquired. 

Tongues of the brick-red granite would be thrust into the earlier 
rock, and the onward movement of the whole might at times detach 
and isolate these, making them appear as fragments included in the 
more basic rock. 


Il. Tur GRaAntte. 


The porphyritic granite which probably formed the first intrusion 
is not seen at Sorel Point, except with the accompaniment of basic 
material, the foreign origin of which can searcely be doubted. At 
La Houle, however, 300 or 400 yards to the east, a porphyritic 
granite, differing in several respects from the brick-red granite of 
the adjacent headland, is seen clearly cutting the basic rock. 


Vol. 55.] INTO DIABASE AT SOREL POINT (NORTHERN JERSEY). 433 


Sections, to be described later, show absorption of basic material on 
the part of the granite and intense alteration in the diabase, so that 
there is considerable probability in the assumption that this granite 
is the same as the porphyritic rock so often mentioned in the fore- 
going pages. 

In a thin section the orthoclase is seen to be seldom or never 
idiomorphie, but to form rounded, irregular junctions with the larger 
grains of quartz. It shows microperthitic structure constantly, and 
not infrequently small plagioclases are embedded in it. The mica 
forms irregular and ragged flakes, either brown or green, with 
considerable pleochroism and absorption. The mineral appears far 
from fresh, and some quantity of secondary material has formed 
along the basal planes. Judging by other sections, there is a 
possibility that this mica is derived from hornblende. A little 
magnetite and some free plagioclase are present. One peculiarity 
found in this and other rocks is the presence of an intergrowth of 
felspar and (presumably) quartz; the latter occurs in fine branching 
threads. This structure, which has been often described, Lacroix 
has figured under the name of quartz vermiculé. 

As the specific gravity is slightly higher than that of the similar 
rocks from the immediate neighbourhood, some of the more basic 
minerals may possibly owe their origin to material absorbed from 
the diabase. 

The typical brick-red granite of Sorel Point, apart from its still 
greater poverty in the dark minerals, shows a different relation 
between the quartz and felspar. As before, the rock is very rich 
in quartz, which sometimes occurs in large rounded or rectangular’ 
grains, but more characteristically in numerous close-set, rounded 
or elongated drops, embedded in, or forming a network with, the 
felspar (Pl. XXIX, fig. 1). Adjacent drops often polarize together,. 
so that the structure is in some degree granophyric. The ortho- 
clase shows plagioclase-intergrowth frequently, but not invariably. 
Free plagioclase is far from scarce. There are a few grains of 
magnetite, and a very occasional intensely pleochroic mica-flake. 
A partial analysis gave the following results :— 


SOE SUlLeay '.. eseiedocaeds 78°10 
AO -Alumineg,..2...<--00s 13°02 
KeOm Potash  ..:..0-0- 4°52 
Na OT Soda... .0...cs0--se- 3°23 

98°87 


A small quantity of iron is included with the alumina, 


Deducting 1 from the alumina-percentage for the iron, the 
mineralogical composition of the rock may be calculated approxi-. 


mately as follows :— 
Plagio- — Ortho- 


clase. clase. Quartz. Total. 
Sia silica. 2...9 hss <ci32 19:71 19°71 38°68 78°10 
AOE AMOI, 64, Hoe sed ai 6°45 DOW paw eases 12:03 
KEW) ee otag a ae. oo scans “30 cs ie eee 4:60 
Nat OF SOA) 0.2: soctecoeeeas 3°12 SO eee unas 3°42 


2958 2989 3868 98:15 
Q.J.G.8. No, 219. 2F 


434 MR. J. PARKINSON ON AN INTRUSION OF GRANITE [Aug. 1899, 


That is, about 30 per cent. each of plagioclase and orthoclase and 
- 40 per cent. of quartz. The plagioclase will be approximately of 
the composition Ab,An.. 


III. Tor Drasasr. 


The diabase is found at intervals along the cliff eastward from 
Les Meuriers, occupying for the most part the higher ground. 
Near the Semaphore on Rosnez Point several small quarries have 
been opened in it. Typically it is a black-and-white speckled rock 
of medium grain, and of a common enough type. As is usual in 
rocks of this kind, the degree of coarseness varies considerably from 
point to point, so that patches, streaks, or veins catch the eye by 
reason of their conspicuous augites, or because of the greater amount 
of felspar which they contain. 

The felspar has commonly a greenish tinge. Asa ty pical instance a 
slide will be described, cut from a specimen collected by Prof. Bonney 
in 1888, and labelled ‘ Diorite near junction with coarse granite, 
La Plaine.’ It differs in no respect from my own slides, except in 
being in a rather fresher condition, for which reason it was chosen 
for description. 

This rock is an ophitic dolerite, though, as the augite is largely con- 
verted into hornblende, the term diabase will be used in describing 
it. The remains of the augite show it to have been of a quite typical 
kind, colourless or with a pale bluish tinge. It is changing by a 
gradual assumption of a brownish tint, or frequently by a sharp 
colour-change, into the usual clove-brown hornblende, which is 
rather unevenly coloured, and shades off into green so as occasionally 
to be almost mottled in appearance. The change is usually peri- 
pheral, the process advancing irregularly inward, but flakes and 
scales of the brown hornblende also form in the body of the 
augite-crystal (Pl. X XTX, fig.2). The green hornblende represents 
a change of the first-formed brown mineral, and there may be a 
still further loss of this green coloration with the assumption at the 
same time of a fibrous or actinolitic structure, in some cases rather 
marked. The felspars are long lath-shaped forms ; they are, judging 
from the extinction-angles, labradorite or a kindred species. A very 
few crystals of apatite, and some magnetite and pyrites, complete 
the list of constituent minerals. 

Occasionally the augite—now almost entirely changed into horn- 
blende—is present in grains, producing a spotted appearance on the 
face of a specimen. Its relation to the felspar is, as before, 
ophitic. A few flakes of a brown, rather fibrous mineral—no 
doubt a mica—occur in the slide, possibly derived from the horn- 
blende. In some slides the felspars are almost opaque from the 
abundance of alteration-products, but there is a tendency for the 
outer parts to be comparatively free from these. A zoned structure 
may then be occasionally observed, but it is not characteristic. 
Sometimes, as in the small quarry near the Semaphore, specimens 
may be found markedly amygdaloidal. 


Vol. 55.] INTO DIABASE AT SOREL POINT (NORTHERN JERSEY). 4030 


IV. Rocks contaIninc DerRIvED MATERIAL. 
(a) Granite with Material absorbed from the Diabase. 


In general terms the diabase occupies the upper part of the cliff, 
the red granite the lower. Here and there, in a position between 
the two, a rock is found intermediate in petrographical character, 
though varying in its composition as traced from point to point. 
It corresponds to the porphyritic variety of granite with absorbed 
material and fragments, described in § IJ. When the amount of 
ferromagnesian minerals is small, the rock approaches the normal 
granite in appearance very closely, but as the basic constituents 
increase in proportion so, of course, the closeness of this resemblance 
is lost. The rock is remarkable for its quartz and large prominent 
orthoclases: finer material, with much biotite and hornblende, 
occupies an interstitial position. The more rapid weathering of 
the latter causes knobs of rounded felspar and quartz to stand out 
on the rough surface of the rock, giving a distinctive character 
which at once catches the eye. A difference in colour, increasing 
in depth with increasing basic material, can be seen readily enough 
in the rocks themselves, especially from a short distance, but it 
cannot be definitely said that the more basic is nearer the diabase. 
‘The rocks at this point are so intermingled on the broken and rugged 
erags of the cliff that it is safe to speak only of general relations. 
Very numerous inclusions of diabase and altered diabase are found 
in this intermediate rock ; often the edges of these fragments are 
more distinct than might have been supposed, seeming to show 
that the absorption of basic material stopped abruptly. All stages 
can be seen within a short distance, from an inclusion apparently 
unaltered, to a patch the origin of which could not have been guessed 
had the transitional steps been wanting. 

The intermediate rock most nearly approaching the granite in 
character offers but few noteworthy points in a thin section. The 
large orthoclases, often with a microperthitic structure, show in 
many cases a zone of quartz-grains near their peripheries. Their 
inner edges are set very nearly in a straight line, their outer 
elongated and more irregular. They seldom appear to be con- 
nected optically with quartz-grains external to the felspar-crystal, 
and doubtless mark merely a phase of consolidation during which 
silica was in excess. Externally to this zone the felspar is con- 
tinued irregularly among adjacent crystals. The parts of finer 
grain interstitial to the larger quartzes and felspars contain a 
considerable proportion of quartz in rounded grains, felspars occa- 
sionally striped, and biotite with some hornblende in small irregular 
flakes. 

A second section, representing a specimen from within a few 
yards of the first, and containing more basic material than it, 
shows an increased proportion of hornblende and mica, the former 
predominating. Both minerals are larger ana better formed than 
in the first slide. In one case a plagioclase has been greatly 

282 


Fig. 1.—Part of an orthoclase-crystal derived from granite, which is- 
embedded in material mostly derived from the diabase (x 43). 


Fig. 2.—Corroded plagioclase lying in an uniform felspathic 
substance (x 54), 


Wol. 55. ] GRANITE AND DIABASE AT SOREL POINT. 437 


corroded and lies half embedded in orthoclase. A few long 
brownish felspars have no doubt been derived from the diabase. 
‘The quartz, late in formation, plays the part of a groundmass, the 
patches isolated in ordinary light often showing optical continuity 
between crossed nicols over large areas; but the structure is not 
granophyric. Occasionally irregular tongues of a felspathic substance 
penetrate the felspars in a way which shows that some change has 
taken place in the latter since their first formation. In ordinary light 
we see that there is astrong tendency on the part of the kaolin of the 
felspars to gather into rounded spots producing a patchy appearance, 
generally more apparent in one part of the mineral than in another. 
Accompanying this, an irregular polarization, more or less pro- 
nounced and foreshadowing the approach of a granular structure, 
becomes visible between crossed nicols in the part of the felspar 
nearest to the region of the later felspathic substance, and seems to 
carry the process of change some way ahead of this invading material, 
if such it be. As the process of breaking up becomes further 
‘advanced, the component granules—before only hinted at—assume 
definite outlines, generally very faint in ordinary light, and finally 
stand as complete individuals, granular or possessing more or less 
definite edges, in an uniform felspathic base (fig. 1), This process 
of reconstitution may go through all its stages in a single crystal. 
‘Viewing such an one in ordinary light, the gradual aggregation of 
the kaolin into spots in passing away from the unaltered part is 
clearly seen, and is shown also, on slowly rotating the stage 
between crossed nicols, by slight differences in the positions of 
extinction in various parts of the crystal. Where the granules 
stand out singly or in groups in the felspathic base, the latter 
embays the altering crystal in a manner most clearly seen between 
crossed nicols, making it appear as though it had invaded the 
original felspar, splitting off portions as it advanced. 

The same structure is found in other slides, and is yet more clearly 
displayed when more basic material is present. The granular 
individuals, when well developed, polarize separately as units ; 
though occasionally adjacent grains polarize together. They show 
sometimes plagioclase-striping, and now and then a zonal structure 
is seen on slowly rotating the stage. The uniform felspathic base 
ain which these granules are set may either behave uniformly or 
may break up between crossed nicols into more or less clearly- 
defined areas, thus making the structure as a whole peecilitic. 
When best developed, this arrangement appears clear and free from 
kaolin. It seems evident that these peculiarities in the felspars are 
due in some way to the action of the absorbed basic rock, which has 
caused part at least of the orthoclase entirely to change its con- 
stitution. Occasionally the corroded crystal is a plagioclase (see 
fig. 2), surrounded by an uniform felspar-substance, for the most 


1 Fig. 2 shows multiple twinning at 6 as a continuation of the twinning of 
the felspar. In the felspathic substance a are embedded numerous smaller 
individuals. The two spaces ¢ are not in continuity with a, but show a different 
polarization. The granules at d represent the breaking up of a felspar-crystal 
in the manner described in the text. 


438 MR. J, PARKINSON ON AN INTRUSION OF GRANITE [Aug. 1899, 


part unstriped, in which stand semi-porphyritic plagioclases. The 
felspar surrounding all is of late consolidation, and extends as a 
kind of matrix for some distance among the adjacent crystals. On 
one side may be seen the grains into which a neighbouring felspar 
is in process of being resolved. 

Occasionally the corroding substance has been quartz. In some 
of these instances, offshoots proceeding from a quartz-grain have 
spread irregularly in the substance of the felspar, but the con- 
tours which the latter mineral presents to the corroding one 
are the same as those described above. At the same time, there 
exists a tendency, not perhaps very strongly marked, for the 
felspar to polarize as a mosaic rather than as a single individual. 
There is, as in other cases, a granular arrangement of the kaolin. 
It seems evident that this composite granular structure, often 
seen in thin sections without the accompaniment of the clearer 
felspathic substance, is a contact-phenomenon due to the mole- 
cular rearrangement of the substance of the felspar under the 
altered conditions attendant on the introduction of basic material. 
The fact that these peculiarities are found beautifully developed in 
large orthoclases derived from the granite, but now embedded in 
dark and basic material (fig. 1, p. 436), points in the same direction, 
namely, that a rearrangement of the particles of the felspar has 
taken place without actual melting, and hence without the introduc- 
tion of new and foreign material into the composition of the mineral 
itself. Such a supposition would lead to the conclusion that the 
ageregation of the kaolin into spots, together with the resolution 
of the crystal between crossed nicols into a mosaic of grains, is an 
early stage of a process which ultimately leads to the production 
of ‘eyes’ of one or more species of felspar embedded in a clear 
uniform base, presumably of orthoclase. In a very few cases this 
shows traces of microperthite. Occasionally, as in fig. 4, p. 436, the 
appearance of the uniform matrix or base of felspar-substance con- 
taining plagioclase-crystals, and appearing, at all events, to corrode 
and split off parts of the kaclinized felspar lying in its neighbour- 
hood, suggests invasion and corrosion by a felspar-substance, in the 
main, no doubt, that of the granite, but probably containing also 
material derived from the absorption of the plagioclases of the 
diabase. The grains produced by the reconstitution of the felspar 
usually appear to form equally well in all directions; but in the 
case of the plagicclase-crystals there seems in some cases to have 
been a formation of grains with greatest facility parallel to the 
twinning-planes of the felspar, and, to some slight extent, at right 
angles to this direction. The corroding quartz also has occasionally 
acted along the direction of twinning. 

One noteworthy point remains, and that is, that in the not very 
common case of a mica-flake embedded in the altered felspar, the 
production of the granular structure in the latter has preceded the 
formation of the former. 

One other peculiarity mentioned before (p. 433) is a structure 
identical with that described and figured by Lacroix as ‘ groupe- 


Vol. 55.] INTO DIABASE AT SOREL POINT (NORTHERN JERSEY). 439 


ments de feldspaths et de quartz vermiculé.’! In the slides this is 
perhaps best seen in the secondary grains into which the felspar is 
resolved, but it often occurs as a border to part of a felspar which 
has not been thus altered. 

The fragments included in this intermediate rock sometimes consist, 
as before mentioned (p. 435), of perfectly recognizable diabase, and 
a thin section of such an one shows that no change has taken 
place which can be ascribed definitely to the action of the acid 
magma. ‘Traces of augite are not common in the slide, but are 
found here and there embedded in the brown hornblende which 
has for the most part replaced them. Like in some other sections, 
this is arranged subophitically as regards the plagioclase. The 
latter is for the most part fairly fresh, and is present in the usual 
long, lath-shaped, interlocking forms. The hornblende exhibits 
locally a rather granular habit, and has occasionally given rise to 
chlorite. A little apatite and magnetite complete the section. 


(5) Diabase with Material derived from the Granite. 


Passing from the rocks where the acid element is the more 
conspicuous to those in which it is less so, there will be noticed 
first, a dark, rather mottled rock which on a casual glance might be 
mistaken for a normal diorite or diabase of a rather fine texture. 
It is found in some quantity near the mass of intrusive granite 
described on p. 432 from La Houle. A closer inspection shows that 
a considerable quantity of a brown-red felspar is present with 
some quartz, the latter mineral sometimes occurring in large rounded 
grains surrounded by narrow rings of small hornblende-crystals. 
This is far from uncommon. Although the proportion of the two 
elements is constant throughout the whole specimen, yet they can 
be seen to be very intimately interstreaked or interveined one 
with the other es though not quite perfectly mixed. In a thin 
section the same arrangement of the constituents is apparent 
with a little care, even if not at the first glance. Patches here and 
there are very rich in orthoclase and quartz, both exhibiting the 
characteristics which have been mentioned before. The former 
appears late in consolidation, encloses crystals of hornblende and 
mica, and may be seen to form a kind of matrix for the other 
minerals. These, if felspar, are often corroded, a point not without 
importance. The quartz bears the same relation to its surroundings 
as does the orthoclase. In those parts where the ferromagnesian 
constituents are conspicuous, orthoclase is absent, quartz very rare. 
No trace of augite remains in this section, though an irregularity 
of colour occasionally seen in the larger plates of hornblende may 
be perhaps regarded as a trace of its former existence ; frequently 
the hornblende is found in granular aggregates associated inti- 
mately with flakes of a bleached and rather fibrous brown mica. 
The felspar, crowded with alteration-products, typically with a 


1 *Minéralogie de la France & de ses Colonies,’ vol. ii (1897) p. 36 & fig. 26. 


440 MR. J. PARKINSON ON AN INTRUSION OF GRANITE [ Aug. 1899, 


clear, external zone, is for the most part, at all events, plagioclase. 
There is also a certain amount of iron-oxide. 

A slide prepared from a specimen of an incompletely dissolved 
fragment which lay in the granitic intermediate rock described 
on p. 435, shows a much more regular distribution of its con- 
stituents than the last. The permeation by the acid magma has 
been much more complete than in the preceding rock. It is 
traversed by one or two quartz-felspar veins, but otherwise is an 
uniform, rather fine-grained rock showing about equal proportions 
of a brown-red felspar (together with quartz) and black minerals 
—hornblende and mica. Large typical irregular orthoclases, and a 
few rather smaller crystals of plagioclase, lie in a granular mosaic of 
quartz and felspar, with hornblende- and mica-crystals of the usual 
types: the former occasionally of some size, but as a whole the 
latter predominate. A most intimate relation exists between these 
two constituents ; flakes of the biotite are embedded in the green 
hornblende in a manner which suggests strongly the production of 
the former from the latter. Although the orthoclase-crystals pre- 
dominate in one part of the slide, yet there is no definite separation 
into a more acid and a more basic region. Plagioclase is common, 
and often surrounded by a layer of unstriped felspar giving a 
practically straight extinction. In a few cases these external 
zones show striping, in continuation of the central older cores. 
The latter are corroded, and often have almost a granular ap- 
pearance, so completely do the edges and corners appear to have 
been removed. It is difficult to make a positive statement, but 
it is most probable that these cores represent the remnants of the 
labradorite of the diabase. 

A peculiar, and at the same time not uncommon, type of rock 
is distinguished by containing a multitude of white or pink ortho- 
clase-crystals rather irregular in shape, as though corroded, and 
of large size, up to about °45 inch in length, set in a fine-grained dark 
matrix. The rock occurs at the junction of granite and diabase, 
and here and there the disposition of the felspars indicates movement 
prior to consolidation. A thin section shows less quartz than in the 
allied rocks above described. It bears a very close resemblance to 
tnat described by Prof. Cole, from Glasdrumman Port, Co. Down." 

‘he spotted structure, well shown in the orthoclases, has been 
already considered. The dominant mineral in the matrix is the 
usual green hornblende: this is scarcely ever idiomorphic. Here and 
there a lighter, rather fibrous centre, together with opaque and 
reddish dust, probably represents the remains of an original augite. 
Biotite occurs sparingly; the quartz fills up interstices between 
the other constituents, usually showing optical continuity over a 
considerable area. Occasionally a corroded basic felspar is seen. 


V. JUNCTION BETWEEN ''HE GRANITE AND THE DIABASE. 


We may now consider the petrographical features presented by 
the two rocks at a distinct junction. The veins of granite which 


1 Sci. Trans. Roy. Dub. Soe. ser. 2, vol. v (1894) p. 239. 


Vol.55.] INTO DIABASE AT SOREL POINT (NORTHERN JERSEY). 441 


frequently penetrate the diabase, provide abundant material for 
study. A specimen from La Houle, showing the contact between 
the diabase and a thin vein of granite within a few feet of an 
obviously intrusive mass, proves (i) that no distinctly defined 
boundary can be drawn between the two rocks; (ii) that shreds 
and fragments of basic material are thickly scattered through the 
substance of the vein. 

A thin section shows at a glance that the diabase has been very 
greatly altered, or indeed reconstituted. The augites and replacing 
brown hornblende, conspicuous in the normal rock, are now repre- 
sented by a multitude of flakes of biotite and green hornblende, 
small and irregularly scattered through the section (Pl. XXX, fig. 2). 
The pleochroism of the biotite is straw-colour for vibrations at right 
angles to the basal plane, and a dark greenish-brown for vibrations 
parallel to it. The absorption is considerable. This mica usually 
occurs in rather square flakes, as a rule with jagged and irregular 
terminations ; not infrequently, in little scattered groups of films and 
elots. The latter habit is still more common in the hornblende ; 
in one case the grains of this mineral are aggregated into a 
glomerulus recalling that described by Prof. Sollas.? 

All the glomeruli seen in sections of these Jersey rocks consist 
of hornblende with small and rare grains of iron-oxide. Occasion- 
ally the circumferences of the glomeruli consist of brown mica 
(Pl. XXX, fig. 1). The mica and hornblende are present in the 
slide in approximately equal proportions, the biotite often associated 
with the hornblende in a manner which suggests its formation from 
that mineral. Occasionally the hornblende, of the usual green type, 
takes on a rather elongated form. A very important point in 
connexion with these altered diabases is the presence of much 
quartz late in crystallization, so as to form a kind of matrix in 
which the other minerals are set. The felspars in the great 
majority of cases have a clearer, more translucent border, and 
frequently show a slight zoning in that part. The outlines that 
they present to the quartz are irregular. They contain abundant 
inclusions of the other minerals scattered through them; and this, 
together with the granular habit of the hornblende and mica, gives 
the section an ‘untidy’ appearance which is rather characteristic. 
The iron-oxide, probably haematite, commonly forms long rectangles, 
often very even and regular. 

Another section of the junction between the altered diabase and 
a granite-vein, itself containing hornblende and some biotite in so 
great a quantity as to be scarcely recognizable as such, shows a rather 
different structure, noteworthy, since the quartz in the more basic 
rock is a rare instead of a common constituent. It seems possible 
that this may be connected with the more basic character of the 
intruder. Hornblende, biotite, and magnetite are present in the 
altered diabase as before, but the form that they assume is much more 
granular. The hornblende especially is found in small grains, 


1 Trans. Roy. Irish Acad. vol. xxx (1894) p. 494 & pl. xxvii, fig. 16. 


442 MR. J. PARKINSON ON AN INTRUSION OF GRANITE [Aug. 1899, 


often arranged in little groups; the components of these may be 
either separated the one from the other, or closely packed together ; 
not infrequently the brown mica is associated with this hornblende 
in irregular films and small flakes. A peculiarity of the hornblende, 
which is here not uncommon, is noteworthy in connexion with 
the derivation of this mineral from augite. An irregular area or 
spot, central or subcentral in position, is seen in the larger flakes, 
distinguishable from the surrounding hornblende by its lighter 
colour. In some cases it appears very slightly fibrous; it may be 
associated with rust-coloured dust, suggesting a ferruginous ex- 
cretion, and usually contains minute colourless and irregular grains. 
The irregular polarization of these augitic remnants, as they pro- 
bably are, prevents a definite extinction from being observed. 

A colourless mineral, which deserves some notice, is present 
abundantly in this section of altered diabase, and occurs in scarcely 
less profusion in that previously described. It is, indeed, a 
usual and characteristic feature in all such sections of modified 
rock from the neighbourhood. The crystals have a strongly-marked 
tendency to occur in parallel groups, often fifteen individuals or so 
in each, but adjacent groups may lie at a high angle to each other. 
Not infrequently they are found in little clusters, without any 
orientation or radial arrangement. The refractive index is fairly 
high, the double refraction low, but this may be due to their 
extreme thinness. The latter quality prevents the extinction from 
being recorded with certainty, but I think that it is very probably 
straight. The crystals appear broken, but not bent, and the 
larger examples often have a cross-fracture or cleavage; occasionally 
segments of the same crystal are separated by other constituents. 
The mineral lies with indifference in all the other constituents, and 
often extends from one to another. That it is not produced in the 
diabase by mere contact may be inferred from the fact that the 
crystals are absent from a fresh, unaltered diabase-inclusion, lying 
in the rock of intermediate character which has been described 
above. Although I have failed to obtain conclusive evidence re- 
garding the extinction, I infer the mineral to be sillimanite from 
its general habit. 

A section has also been prepared showing the contact, which is 
very obscure and irregular, between the altered diabase and @ 
vein of mixed rock, very basic-looking, which contains large rounded 
orthoclases. It is of interest, since it shows the remains of an 
augite corroded by quartz. The mineral, which is of a very pale 
green and rather fibrous, is altering to dark green hornblende. 
Sundry grains, non-pleochroic or very feebly so, which are found 
in small groups, for the most part embedded in quartz, are also 
most probably the remains of augite. These are on the granitic 
side of the junction. The basic material included in the granite 
consists of fairly well-formed flakes of hornblende and mica, and, 
in addition, of clusters of interlocking grains of the former mineral 
resembling the glomeruli noticed above. Occasional flakes of mica 
are mingled with these. The quartz forms, where it occurs, a kind 


J oa 


Vol. 55.] INTO DIABASE AT SOREL POINT (NORTHERN JERSEY). 443 


of matrix to the other constituents, and corrodes the felspars. 
Zircons are seen not uncommonly in the larger flakes of hornblende 
surrounded by dark halos. In other sections, the younger rock 
contains less hornblende and mica. 

The changes produced in these granite-veins are much less 
marked than those found in the diabase. Quartz in large irregular 
grains is present as in the normal rock, and bears the-same relation 
to the felspar. This shows occasionally a microperthitic structure, 
and less than might have been expected of the curious breaking- 
up and reconstitution described before (p. 437). Plagioclase 1s 
fairly abundant, and, judging from the low extinction-angles, is 
oligoclase or a closely-allied form. Here and there little patches, 
consisting of biotite and hornblende, are found identical in character 
with the same constituents in the more basic side of the junction. 

The apparent facility with which important mineralogical changes 
are induced in the diabase is rather remarkable. The basic rock 
close to the junction is of an entirely different type from the diabase 
in its normal state. The early stages of the change are illustrated 
by a thin section cut from the heart of a clearly-defined wedge- 
shaped fragment, some 3 inches long, lying with others like a 
breccia in the pink granite. For instance, biotite, so common when 
alteration has proceeded further, is scarce or almost entirely absent ; 
the augite has been replaced by green hornblende, leaving ferru- 
ginous dust and a slight suspicion of a fibrous structure as the sole 
remnants of its former existence. The hornblende is, however, 
often in a finely-granular condition, implying total reconstitution 
of the original pyroxene. This variety has a tendency to become 
idiomorphic. Occasionally small biotite-flakes are embedded in the 
hornblende- substance, in a way that strongly suggests their secondary 
nature. Plagioclase abounds, so that the only traces of the foreign 
magma consist in the occasional presence of quartz-grains together 
with some untwinned felspar. Hornblende is by no means absent 
from these patches, which are closely dovetailed into the surround- 
ing rock. Iron-oxide, in the form of grains and rectangles, is 
scattered abundantly through the section, and the colourless 
acicular crystals noticed before (p. 442) are not absent. 

Few new points are shown by another section cut from the same 
specimen of a fragment in the later stages of dissolution, when it is 
interesting to note the great preponderance of biotite over horn- 
blende, the difference being apparent at once, even to the naked eye, 
on placing the two slides side by side. The large quantity of mica 
present when the acid element is in excess of the basic is a well- 
marked feature in many rocks from the neighbourhood. Clusters 
of hornblende-crystals and graius are found here and there, but not 
abundantly, and may be taken to represent the remnants of diabase- 
fragments. The presence in the hand-specimen of shreds, frag- 
ments, and irregular patches of basic material renders such a 
conclusion practically self-evident. A few corroded plagioclases, 
occasionally zoned, most probably are partially absorbed felspars 
from the diabase. 


444 MR. J. PARKINSON ON AN INTRUSION oF GRANITE [ Aug. 1899, 


The following are the specific gravities, determined by a Walker’s 
balance, of some of the rocks described :— | 


Aplite, specimen analysed, Sorel Point .............+ wee De 
Porphyritic granite, the earliest intrusion ............... 2°60 
‘Intermediate rock,’ Sorel Point. Granite greatly 
predomimeatineyl <5 202b0. 05. eee eeeeeees eee 
The Gamemone, Dasie):..8).0.5. a ance dene te eae ate 2°67 
Diabase with material derived from granite (p.439)... 2°84 
Diabase with much less granitic material: silica- 
PETEeMtA TO ON Le. oc lcees Mennencasee Att morte ee eae ces 2°92 
Normal ‘diabase™, 2a. sade. uk lene soe coer 2°92 to 2°94 


VI. Comparison oF THE PHENOMENA WITH THOSE OBSERVED IN 
OTHER DistTRICTSs. 


It is scarcely necessary to remark that the facts described in the 
foregoing pages present great analogies with those recorded by 
Prof. Sollas,* Mr. Harker,” and Prof. Cole,’ from the districts of 
Barnavave, Strath, and Sheve Gallion respectively. But Mr. 
Harker’s remark, in his account of the granophyres of Strath, 
that ‘the enclosed rock-fragments have not been derived from the 
rocks which border the intrusions as seen in outcrop, points to 
an important difference between the rocks which he describes and 
those around Sorel Point. The regularity of distribution of the 
absorbed material ‘through the involving magma prior to the 
consolidation of the latter in its present surroundings,’ to which 
he refers, is but occasionally found in these Northern Jersey rocks, 
and then apparently to no great extent. The mineral changes 
resulting from the amalgamation of two magmas show, as was to 
be expected, both similar and dissimilar points. In La Plaine the 
action on the felspars recalls to some extent the work of Back- 
strom * on solution-spaces, formed in the foreign crystals of some 
dykes, rather than the alteration by injection with orthoclase and 
quartz found in the bytownite of Barnavave; but the most striking 
change has been concerned with the acid felspars, and not with the 
basic ones of the older rock. The latter seem, not uncommonly, 
to have been completely absorbed. 

A remarkable point of difference between the mixing at Strath 
and that around Sorel Point consists in the absence of biotite, at the 
former locality, as a product of the assimilation and recrystal- 
lization of the augite. The mineral, however, occurs to a limited 
extent in the immediate neighbourhood of fragments of basic lava 
included in the gabbro of Carrock Fell.’ The restriction of this 
constituent to a zone of a few feet around these inclusions, and the 
fact that it is foreign to the normal gabbro implies, as Mr. Harker 
points out, difficulties in the way of diffusion at the time when it 


1 Trans. Roy. Irish Acad. vol. xxx (1894) p. 477. 

2 Quart. Journ. Geol. Soe. vol. li (1896) p. 320. 

8 Sci. Trans. Roy. Dub. Soc. ser. 2, vol. vi (1897) p. 213. 

4 Bihang till K. Svenska Vet.-Akad. Handl. vol. xvi (1890-91) pt. ii, no. 1. 
> Quart. Journ. Geol. Soc. vol. | (1894) p. 331. 


Vol. 55.] INTO DIABASE AT SOREL POINT (NORTHERN JERSEY). 445 


was produced, and he concludes from this that the formation of the 
mica is in relation to the acidity of the more central part where these 
fragments are found. It is also interesting to note that the 
granophyre contains a little biotite on approaching the gabbro,’ due 
to the fact that portions of the highly basic gabbro have been 
incorporated with the acid magma near the junction of the two 
rocks. Biotite is also one of the products of the alteration of 
diallage at Barnavave. Mr. T. H. Holland, in his paper on ‘ Augite- 
diorites with Micropegmatite from Southern India,’? has remarked on 
secondary ‘ opaque-iron ores, hornblende and biotite,’ situated on the 
margins of the augite which abut directly against the micropegma- 
tite. This instance is, however, scarcely comparable with those of 
the Jersey rocks if, as Mr. Holland believes, the micropegmatite 
represents the final product of consolidation as opposed to a later in- 
jection of acid material—a difference which he carefully emphasizes. 

The biotite in the biotite-gneiss of Sark * is an excellent instance 
of the production of this material by the second of the two methods, 
closely resembling that followed in the rocks around Sorel Point. In 
some cases it appears clear that a total reconstruction of a fragment 
has taken place, with the formation of mica as a result of the union 
of the hornblende of the diabase and the alumino-alkaline consti- 
tuents of the granite. In the Jersey rocks the tendency to form 
hornblende seems to have been very strong, for thin sections of the 
basic rock, apparently not greatly impregnated with the acid magma, 
show scarcely a trace of augite in the midst of the replacing horn- 
blende; so that we can hardly expect the clusters of granular 
augites mentioned by Prof. Sollas as one of the results of the 
change in the diallage of the Irish rock. One instance only of 
anything of this kind has been seen (p. 442). There is, however, ar 
interesting likeness between one of the varieties of granophyre which 
the same author has described,* namely, that containing biotite 
and hornblende, and a specimen collected by the Rey. Edwin Hill in 
Alderney, and given by him to Prof. Bonney. 

Prof. Sollas, in describing the rock from Sheve Gallion, calls 
special attention to the occasional presence of a diallage-core sur- 
rounded by olive-green amphibole, and that again by an external 
border of biotite. This characteristic, with others, leads him to 
comment on the possibilities of distinguishing homogeneous rocks 
from rocks of heterogeneous formation, even when the field-relations 
are not known. Similarly, the augitic cores surrounded by horn- 
blende and these again by mica, diagrammatically shown in the 
Alderney rock, become especially interesting when looked at in the 
light afforded by the rocks of the neighbouring island. 

I am indebted to the kindness of the Rev. Edwin Hill and Prof, 
Bonney for permission to describe a thin section cut from this specimen. 
In this the three minerals—augite, hornblende, and biotite—form 


1 Quart. Journ. Geol. Soc. vol. li (1895) p. 133. 
2 Ibid. vol. liii (1897) pp. 413-414. 

3 Ibid. vol. xlviii (1892) p. 131. 

4 Trans. Roy. Irish Acad. vol. xxx (1894) p. 497. 


446 MR. J. PARKINSON ON AN INTRUSION OF GRANITE {[ Aug. 1899, 


small groups or nodes in a rock whose principal constituents for the 
rest of the section are quartz and felspar. The fibrous augite-cores, 
identical with the fragments of the same mineral described on p. 442, 
are surrounded and penetrated by patches of dark green hornblende, 
with which a dark brown and straw-coloured biotite is most inti- 
mately mingled. Grains and dust of iron-oxide, and rarely pyrites, 
are scattered through these nodes. ‘The biotite, which occurs in 
some profusion and often in large plates through the rest of the 
section, together with decayed and decaying augites, is very late in 
formation and extremely irregular and tattered in outline. There are 
a few colourless crystals of a mineral resembling that described as 
sillimanite on p. +42, and occasionally a zircon. Corroded felspars, 
striped and unstriped, often with a peripheral zoning, lie in a 
granular aggregate of felspar and quartz. The latter is abundant, 
though any single grain seldom reaches large dimensions, nor does the 
mineral preserve its optical continuity over a comparatively large area 
as in some slides from Jersey. This mixture of quartz and felspar 
in irregular and subangular grains is not the least peculiar feature 
of this unusual type of rock. Mr. Hill’s remark, after describing 
sundry appearances in the field, that ‘it is surely not necessary to 
assume that every coarsely crystalline mass is throughout of simul- 
taneous date,’ ' seems to me in all probability to suggest the true origin 
of the rock. The evidence of the production of biotite from the 
replacing hornblende is, I think, conclusive; and it is of great 
interest to find the double change of the pyroxenic mineral exhibited 
so clearly in this slide. In Jersey, the augite appears to be less 
stable and the production of biotite from hornblende not to coexist 
with the earlier change of augite into hornblende, or at all events 
not to the same extent. 

Prof. Sollas has found in the rocks of Barnavave that ‘in 
jnnetion-specimens uralitization is met with, but in xenocrysts this 
has not been observed ; in their case the diallage directly passes into 
a sage-green hornblende.’* In Jersey the brown hornblende, which 
forms so readily from the augite of the diabase, is not met with in 
the reconstituted rocks, nor is the actinolitic fringe, found here and 
there in connexion with the ophitic plates of the former, seen with 
the semi-porphyritic or granular green hornblende characterizing the 
latter. 


It was mentioned on an earlier page that Noury has recorded 
more than one intrusion of granite into the so-called diorite. That 
from the south-east of the island has still to be described in detail. 
It possesses many features in common with the intrusion so admirably 
shown in the cliffs round Sorel Point. But the field-evidence is 
rather more obscure, and the study of thin sections of the rocks 
has revealed sundry points which render it advisable to postpone a 
description of the district to another occasion. Inthe more northerly 


1 Quart. Journ. Geol. Soe. vol. xlv (1889) p. 381. 
2 Trans. Roy. Irish Acad. vol. xxx (1894) p. 494. 


QUART. JOURN. GEOL. SOC. VOL. LV. PL. XXIX. 


GRANITE FROM SOREL POINT, AND OPHITIC DIABASE 
FROM LA PLAINE. 


a 


pang TO 


a 
a 


‘i 


QUART. JOURN, GEOL, SOC. VOL. LV. PL. XXX. 


72 DERBY & LONDON. 


- 


MODIFIED DIABASE FROM LE FOSSE VICQ, AND THE SAME MORE 


ALTERED AT JUNCTION WITH GRANITE FROM LA HOULE. 


Vol. 55.] INTO DIABASE AT SOREL POINT (NORTHERN JERSEY). 447 


example, however, which has been described in the foregoing pages 
the evidence afforded by microscopic study, no less than that obtained 
in the field, shows the great alterations that have taken place in 
the composition of the diabase, and of the granite intrusive in it. 
Starting from the former in an unaltered state, we have traced the 
gradual change produced by the penetration of the acid magma, a 
change at first confined to nests and patches of foreign minerals em- 
bedded in diabase otherwise scarcely altered. As the intruder gains 
in strength so is the older rock gradually overcome, till at last we have 
found neither diabase nor granite, but a compound of both which is 
intermediate in character between them. We have seen the acid 
magma in abnormal states through the assimilation of fragments 
of the diabase in varying degrees, and we have traced the steps which 
lead from those to the normal rock. 

The phenomena seem inexplicable as any form of differentiation 
an situ, but indicate the local melting down, partially or sometimes 
completely, of one rock by another of very different chemical 
composition. 


I wish, in conclusion, to express my deep indebtedness to Prof. 
Bonney for invaluable advice and help, especially in that portion of 
my work.to which the latter part of the Introduction refers. My 
sincere thanks are also due to him for his kindness in looking through 
the manuscript of this paper, and for permission to have slides 
prepared from several of his specimens from the Channel Islands. 


EXPLANATION OF PLATES XXIX & XXX. 
Puate XXIX. 


Fig. 1. Brick-red granite from Sorel Point, forming the later intrusion of 
the acid magma. On the left is a group of quartz-grains ; the centval 
clearer spaces are also quartz, three or four adjacent grains polarizing 
together. The large felspar on the right is a plagioclase. X50. 

2. Ophitic diabase from La Plaine. The section shows two felspar-crystals 
embedded in augite, much of which is changed into hornblende. Near 
the centre two grains of magnetite may be seen in the latter. 50. 


PruatE XXX. 


_ Fig. 1. Section of modified diabase from Le Fossé Vicq, containing large ortho- 
clases derived from the granite. Part of one of these can be seen at 
the top of the figure. On the right are several glomeruli of hornblende- 
grains surrounded by dark biotite-flakes. The majority of the dark 
flakes scattered though the section are hornblende. A small nest of 
quartz-grains spanned by a mica-flake can be seen halfway between the 
centre and the lower edge of the figure. The clear outer edges of 
the felspars are well seen in several instances. Sillimanite, which is 
present in the section, cannot be distinguished in the figure. x8. 

2. Part of the section described on p. 441. The figure shows hornblende, 
biotite, felspar, and quartz. Towards the left and upper part of the 
field may be seen a wedge-shaped crystal of hornblende. The silli- 
manite cannot be distinguished. X16. 


448 GRANITE AND DIABASE AT SOREL POINT. [ Aug. 1899, 


Discussion. 


Prof. Sortas remarked that, through the kindness of the Author, 
he had been able to examine the slices of the rocks described under 
the microscope, and had recognized some of the characteristic effects 
which result from the action of a fused rock on one previously 
consolidated: the phenomena were much more striking in hand- 
specimens than in microscopic preparations, and in these enquiries 
the field-evidence was of the first importance. It was natural to 
regard the hornblende and biotite surrounding augite as products of 
the interactions of the magma on a xenolith ; but another possibility 
shouid be borne in mind, for the three minerals might be excreted 
in this order from a homogeneous magma as a result of increasing 
acidity or changes in pressure and temperature. Evidence was 
still needed to decide whether the associated hornblende and biotite 
were derived directly from the magma, or resulted from corrosion 
of included augite. 

The AurHor thanked the Society for the reception accorded to 
his paper, and briefly replied to the question put by Prof. Sollas, 
saying that the production of biotite from augite in these Jersey 
rocks principally depended on the extent of the mixture with the 
eranite-magma rather than on questions of temperature and 
pressure, pointing out that this was clearly shown by specimens on 
the table. 


het 


Vol. 55.] THE RHYOLITES OF THE HAURAKI GOLDFIELDS. 449 


30. Norges on the Ruayottres of the Havraxr Gonprierps (NEw 
Zeatand). By J. Parx, Esq., F.G.8., and F. Rurey, Esq., 
F.G.S. With Curmicat Anatyses by Partie Hotranp, Esq., 
F.L.C., F.C.S. (Read May 24th, 1899.) 


Part I.—Cuaracreristics of the Ruyouites in the Frexp. 
By James Parx. 


[Prats XXXI—Map.] 


New ZeALAND, during the Secondary period, seems to have been singu- 
larly free from volcanic disturbances, but after the advent of the 
Eocene it again became the scene of outbursts which have prevailed, 
with only short periods of cessation, up to the present time. The 
eruptions of Tertiary date were generally more widespread than those 
of recent times, their ejections sometimes affecting many hundreds 
of square miles. 

The ejections of the early Tertiary eruptions were principally basic ; 
those of the middle Tertiary, semi-basic; of the older Pliocene, 
acidic; and of the newer Pliocene and recent, acidic, semi-basic, 
and basic. 

The ,Pliocene acidic eruptions devastated a wide area in the 
central portion of the North Island, smothering thousands of square 
miles with rhyolitic lavas, tuffs, and pumice, which now form barren 
plains and bare, flat-topped ranges. The chief centres of eruption 
lay in the Taupo, Rotorua, and Tauranga districts and the Hauraki 
peninsula. It is in connexion with the rhyolites of the last-named 
district that these notes are written. 

The Hauraki peninsula is situated in the province of Auckland, 
and lies between the Firth of Thames, on the west, and the Pacific 
Ocean on the east. Altogether it covers an area of about 1,000 
square miles. Its surface is diversified with rugged, forest-clad 
mountain-ranges, cut by deep ravines. 

The basement-rocks consist of Paleozoic (probably Devonian) 
slates and grauwacke, which generally occur in rapidly alternating 
thin beds or layers. Near Cabbage Bay a small isolated patch of 
richly fossiliferous marly clays, and limestone of Lower Eocene age, 
rests directly upon the denuded surface of the Palzozoic slates; while 
throughout the length and breadth of the peninsula a vast accumu- 
lation of andesitic lavas and tuffs is piled on both the slates and 
Eocene strata indifferently, to a depth in some places of 3000 feet. 

These andesites are the gold-bearing rocks of the Hauraki penin- 
sula, the prevailing variety being an augite-andesite, in which the 
augite is more or less replaced by hypersthene. In the Mercury 
Bay and Waihi districts, the andesites are covered by heavy flows of 
rhyolite and accumulations of rhyolitic ash. 

Both the andesitic and rhyolitic eruptions appear to haye been 


@.J.G. 5: No. 219. 26 


450 MBESSRS. J. PARK AND F. RUTLEY ON THE [Aug. 1899, 


followed by periods of intense solfataric action, resulting in the 
formation of extensive siliceous deposits, some of which have proved 
richly productive of gold and silver. ‘The present solfataric action of 
‘Taupo, Rotomahana, and Rotorua has more or less affected the 
rhyolites which occupy these regions. 

While engaged in the geological exploration of the Hauraki 
Goldfields,* an exploration extending over a period of seven years, 
the author collected many varieties of rhyolite, typical examples of 
which were submitted to Mr. Rutley for examination. A few brief 
notes on the principal characteristics of the rhyolites as they appear 
in the field may be of some interest, when read in connexion with 
the description of their microscopic structure. 

On the surface the rhyolites are generally grey or yellowish- 
grey. In the neighbourhood of Waihi they are frothy or pumiceous. 
Between Waihi and Waikino they are brecciated, with small 
angular enclosures of black pitchstone, or partially devitrified glass, 
which impart to the rock an ashy or tufi-like appearance, especially 
on weathered surfaces. When deeply quarried into, the pumiceous 
rhyolite is seen to pass insensibly into a tough, fine-grained, drab 
or dull purple rock, in which clear glassy crystals of sanidine are 
conspicuous. 

The rhyolite weathers into a soft grey rock, which breaks into 
cuboidal masses whose sides are often 10 inches square; when 
much decomposed it outwardly resembles a claystone, and, hke 
it, crumbles into a tenacious clay on exposure to atmospheric 
influences. 

The rhyolites of Mereury Bay and Tairua often exhibit a strongly- 
marked spherulitic structure, many of the spherulites ranging from 1 
to 2 inches in diameter. In these districts, moreover, they possess a 
finely-banded structure, in which thelamine are apparently coincident 
with the fluxion-planes. A beautiful example of banded structure 
is seen at the mouth of the Tairua River, on the sea-face of Te Paku 
Island. For a distance of 7 mile the lamine are extremely thin, 
and so strongly folded that the rock, viewed a little way off, presents 
a remarkable resemblance to a highly-contorted gneiss or mica- 
schist. 

The rhyolites which form the lofty bare hills around the Waihi 
Plains are highly quartzose and often granitoid in appearance. 
They are seemingly the result of eruptions earlier than the pumi- 
ceous rhyolites, which form the floor of the plains, and wrap round 
the flanks of the enclosing hills of andesite on the north, and of 
quartzose rhyolite on all other sides. Boring operations on the 
plains disclosed the presence of two distinct streams of rhyolite, 
with grey pumiceous upper surfaces. 

In the Mercury Bay and Tairua districts the rhyolite-flows cap 
the higher hills, and along the valleys present long lines of steep 
escarpment, the faces of which are carved into deep vertical folds or 
corrugations, the massive stony drapery backed with evergreen 


1 Trans. N. Z. Inst. M. E. vol. i (1897) pp. 1-105. 


od 


Vol. 55-] RHYOLITES OF THE HAURAKI GOLDFIELDS. 451 


forest producing, when viewed from a distance, a very pleasing and 
picturesque effect. | 

Up to the present time no direct evidence has. been found in the 
Hauraki area to fix the exact age of the rhyolites, which are found 
resting indifferently on the gold-bearing andesites, of probably 
Lower Miocene age, and on some volcanic tuffs and. breccias to 
which an Upper Miocene age has been ascribed by Sir James Hector, 
Capt. F.W. Hutton, and other New Zealand geologists. The rhyolites 
are followed by Pleistocene and recent deposits, but, as already stated, 
they appear to be continuous in extension, and contemporaneous with 
the rhyolites of the King Country and. Wanganui regions, which 
have been shown by the Author, from their association with the 
younger marine Tertiaries there, to range from. older to newer 
Pliocene.* 


Part Il.—Zhe Microscopic CHARACTERS of the Ruyourrss. 
By Franx Rottey.. 


[Puarns XXXII-XXXIV.] 


THE specimens were collected by Mr. James Park, F.G.S., and are 
numbered consecutively, but their sequence indicates nothing more 
than the order in which they were examined. In some cases the 
specimens, when received, bore numbers, which are placed in 
brackets. 


H,. Omahu.—This is a pale lithoidal rock, consisting of parallel 
alternating pink or pinkish-grey and very delicate white bands, 
which are seen under the microscope to consist almost exclusively 
of spherulites. The latter vary from inch in some bands to 
only 54,5 inch in diameter in others. These spherulites give a 
negative sign when tested withthe teinte sensible No.2. The 
edges of the spherulitic bands often consist of divergent fibres, the 
divergence proceeding from points on the margins of the bands. 
Viewed under a fairly high power, the fibres constituting the 
spherulites appear to be margarites. The spherulitic bands are 
sometimes separated by nearly isotropic bands, in which some very 
slightly altered vitreous matter appears still to exist, while in 
places irregular anisotropic patches and a hazy spherulitic structure 
- can occasionally be discerned. Small aggregates of quartz and 
felspar sometimes occur in the spherulitic bands, the former mineral 
being clearly recognizable in certain sections by its positive, uniaxial 
interference-figure. The felspar, when examined by Becke’s 
method, is seen to have a lower refraction than Canada balsam, 
while its extinction-angle, 21° with ¢ in a section parallel to (010), 
clearly shows that it is sanidine. Very diminutive cubes of pyrites 
occur here and there in the section.” (Pl. XXXIV, fig. 5.) 


1 N. Z. Geol. Surv. Reports: Explorations, 1886 [1887]. 
2 An analysis of this rock, made by Mr. Philip Holland, is tabulated on 


p. 467. 
262 


452 MESSRS. J. PARK AND F. RUILEY ON THE [Aug. 1899, 


H,. Omahu.—A pale greyish- to pinkish-white rock, which 
under a pocket-lens is seen to consist of irregular streaks of pink 
and white matter, the streaks having a rudely radial disposition 
about ill-defined centres. The structure is evidently spherulitic, 
the spherules appearing to range from about ? inch in diameter 
downward. The boundaries of the individual spherulites are 
not very distinct. A section of this rock under the microscope 
shows lappet-like shreds of devitrified glass, which in ordinary 
transmitted light vary from colourless to. pale brown or pinkish- 
brown, and are chiefly devitrified by globulites. These shreds 
exhibit strain-polarization between crossed nicols, extinguishing 
when the principal section of one of the nicols is parallel to the general 
direction of any one of the arms or parts of processes or fingers 
belonging to the spherulites, the bodies of which do not happen to 
occur in this particular section. The fingers sometimes bifurcate, 
and the branches appear,‘in section, to be rounded at the ends, 
resembling in outline the lobes of the common sea-mat (Flustra) ; 
they very commonly show a distinct marginal growth of crystalline- 
fibrous character, similar to that of ordinary spherulites. The 
secondary nature of this surface-growth or envelope on similar 
finger-like portions of spherulites was long ago pointed out by 
Vogelsang* in a rhyolite from Tolesva, near Tokay. ‘The branches 
or fingers of devitrified glass are, as already mentioned, very irre- 
gular, and consequently discontinuous in section, part of a branch 
being often represented by rudely circular, oval, or amcebiform 
patches. The bodies to which the arms or branches belong are 
described by Rosenbusch as spherulites with pseudopodium-like 
processes: a good example is shown in pl. iv, fig. 4, in vol. 1 of 
the 3rd edition of his ‘ Mikroskopische Physiographie der Massigen 
Gesteine, and on p. 596 of the same work these bodies are spoken 
of as mikrofelsitspharolithe. 

If one of these bodies could be separated from the surrounding 
colourless spherulitic matter—that is, if one of them, with all its 
ramifying arms and fingers, could be isolated—it would probably 
present the appearance of a coralloid growth with irregular branches 
emanating from a centre, or from what may approximately be 
regarded as a centre, since the central portion does not appear to 
be a distinct spherulite, but rather an indistinct aggregate of 
spherulitic growths with a tendency to a radiate structure about a 
common centre pervading the mass. This is well shown in the 
section made from the specimen [109] described on p. 455. 

The spherulites which constitute the remainder of the rock give 
a distinct dark cross when Oa between crossed nicols, and vary 
from about ;4, to about 54. inch in diameter. Small nests of 
quartz are present here and there, but the rock is essentially com- 
posed of the two varieties of spherulites already described, namely :-— 
the large, brownish, and once-vitreous spherulites with arms, and 
the smali ordinary spherulites which lie between those arms and 


1 «Die Krystalliten,’ 1874, ed. by I’. Zirkel, p. 148. 


t Volrs5.| RHYOLITES OF THE HAURAKI GOLDFIELDS. 453 


constitute the greater portion of the rock. Doubtless the former 
as suggested by Vogelsang, have, after solidification, been again 
partially fused, so that the surfaces and ends of the arms became 
rounded. A spherulitic envelope was then formed around them, 
and subsequently the smali spherulites were developed. 


H;. Omahu.—tThis is a somewhat deep pinkish-grey rock, which, 
on the cut surface, is seen to be traversed by a few buff-coloured 
continuous bands, between which are small irregular markings of a 
like pale colour. 

The microscope shows the rock to be composed of alternating 
spherulitic and microcrystalline bands. The spherutites are of the 
ordinary kind, having a radiating-fibrous structure, and giving the 
usual dark cross between crossed nicols. In ordinary transmitted 
light, however, the section shows two extremely interesting bands in 
which more or less transverse sections of the arms of brownish sphe- 
rulites of Rosenbusch’s microfelsitic type are seen (Pl. XXXII, 
fig. 4); these, between crossed nicols, become more or less dark. 
They are not affected by the subsequent development of spherulites 
of the ordinary radiating fibrous-crystalline type. The globulites by 
which the larger and earlier-formed brownish spherulites are devi- 
trified often form margarites and longulites, while trichites are also 
present. The margarites, or rectilinear series of globulites, show a 
general tendency to run in the direction of the branches or fingers 
of the spherulite, but they not unfrequently cross one another. 
These and the curvilinear trichites may distinctly be seen to consist 
of lines of globulites when magnified 250 diameters (Pl. XX XIII, 
fig. 5). Rosenbusch makes a distinction between such curvilinear 
globulitic forms and true trichites, although he admits that a 
passage exists between them, consisting in a more or less longulitic 
fusion of the globulites.* 

The section contains numerous opaque octahedra which appear 
black in reflected light: these are rarely more than =4, inch in 
diameter. Small specks of a yellow colour and metallic lustre may 
also be seen in reflected light. The black octahedra may be re- 
garded as magnetite; the yellow specks are pyrites. Being in doubt 
whether some of the latter might not be gold, 1 submitted a 
sample of this specimen to Mr. Philip Holland, who kindly ex- 
amined it by Skey’s method and found that, although pyrites was 
present, there was no trace of gold. 


H, Mercury Bay.—A black glass with a very few white 
spherulites. Judging from its general appearance, it seems to be an 
ordinary obsidian. 

A section of this rock, when viewed under the microscope between 
crossed nicols, appears to be completely isotropic, with the exception 
of one or two brown spherulites, which have a radiating structure, 


1 « Mikrosk, Physiogr. d. petrogr. wicht. Mineral.’ 3rd ed. vol. i (1892) p. 35. 


A454 MESSRS. J. PARK AND F. KUTLEY ON THE [Aug. 1899, 


and consequently give a dark cross. One of these spherulites 
encloses a small felspar-crystal, the nucleus of which seems to be 
oligoclase, while the surrounding zone does not conform with the 
outline of the irregularly-bounded nucleus, but shows definite 
crystal-boundaries, which appear to have undergone slight corro- 
sion. The outer zone may possibly be sanidine. This inclusion 
contains two prisms of apatite. In ordinary transmitted light the 
section is seen to contain numerous trichites and longulites, the 
latter especially as a rule forming narrow bands in the direction of 
flow (Pl. XXXII, fig. 1), A few globulites are also present. The 
trichites in this section are not built up of globulites, but consist of 
delicate, opaque, continuous, hair-like rods, tapering towards the 
ends like eyelashes. A few small crystals of pale green epidote, 
in one case twinned on (100), occur in this slide. 


H,. Mercury Bay.—tThis specimen is rather small, but clearly 
shows the contact of a pale grey or white rock with a dark one, 
and pellets or spherulites of the latter form coarse dots in the white 
portion. 

In thin section the dark obsidian-hke parts appear, in transmitted 
light, of a pale yellowish to reddish brown, and are seen under the 
microscope to consist of spherulites, each spherulite measuring on an 
average somewhat over ;/, inch in diameter. They are composed 
of brown imperfectly devitrified glass (or microfelsite of 
Rosenbusch). They have a radiating-fibrous structure, and although 
some of them give a perfectly circular section, the majority are more 
or less polygonal, as though pressed together. These spherulites 
exhibit a dark cross when viewed between crossed nicols, and the 
cross in some cases becomes considerably deformed during rotation 
(Pl. XXXII, fig. 2), occasionally opening out and forming two dark 
brushes, as in the interference-figures of biaxial crystals. In 
addition to these large spherulites much smaller ones occur, deeply 
stained by ferric oxide. They are sometimes only partially deve- 
loped, forming a marginal growth on larger spherulites or between 
them. The light lithoidal portion of the rock shows beautiful 
perlicity (Pl. XXXII, fig. 3), one perlitic crack occasionally sur- 
rounding four or five other systems of perlitic fissures. This perlitic 
portion of the rock is pervaded by a microcrystalline to obscurely- 
small spherulitic devitrification. The large brown spherulites are 
traversed by very delicate and approximately parallel dark lines, 
consisting of trichites. Under a 14-inch objective the latter are 
sometimes seen to form more or less radiating groups of fine 
opaque hairs, which now and then describe graceful curves, but the 
majority of the trichites appear to be drawn out in the original 
direction of flow in the lava. Little crystals and grains, apparently 
of magnetite, also occur in the brown spherulites, as also a few 
colourless ‘crystals and grains, which are here and there seen to 
form the nucleus of a spherulite. The spherulites are optically 
positive. 


Vol. 55. ] RHYOLITES OF THE HAURAKI GOLDFIELDS. 455 


H, [6]. Omahu.—tThis is a pale bluish-grey lithoidal rock, with 
indications of a spherulitic structure. 

‘The section shows under the microscope porphyritic crystals of 
sanidine, andesine, and labradorite, all more or less corroded, so 
that none of them present sharp angles and edges. The rock in 
which these crystals occur consists of two generations of spherulites 
(as in H,, already described on p. 452), the earlier microfelsite- 
spherulites being of the large brown type, while those of the 
second generation are nearly or quite colourless, and of the radiating 
erystalline-fibrous type common in acid lavas. Both kinds of 
spherulites are impregnated with globulites, and in the smaller ones, 
when seen in very thin section, the globulites appear to form 
margarites disposed obscurely ina radial manner. The large brown 
spherulites rarely show any perfectly isotropic matter, the original 
glass having been almost wholly devitrified by globulites, trichites, 
and apparently fibres which may have resulted from the coalescence 
of irregular lines or streams of globulites and longulites. Where a 
porphyritic crystal is enveloped in the brown material these lines 
are seen to sweep round it, indicating an ordinary fluxion-structure 
(Pl. XXXIV, figs. 1 & 3). The slide is in fact made up of sections 
of the arms, or, as Rosenbusch terms them, the ‘ pseudopodium- 
like processes,’ of these brown mierofelsite-spherulites and the 
colourless spherulites of the second generation. The porphyritic 
crystals of felspar are more or less corroded, and were evidently 
floating in the magma before the microfelsite-spherulites were 
formed, since they are sometimes enveloped by the latter. Nests 
and patches of tridymite occur in many parts of the section, and a 
small amount of quartz is present either in splice grains or 
forming little mosaics. 


H, [109]. Omahu.—This is a yellowish-white, lithoidal rock, 
containing small lithophyse ranging up to ? inch in diameter. 
They show a concentric shelly structure, the interspaces between 
the shells being hollow, while the inner surfaces have a rather deep 
brown colour, and often show a roughened or punctate appearance 
under a pocket-lens. 

The section of this rock passes through portion of a lithophyse 
as well as through large brown microfelsite-spherulites and small 
spherulites of the ordinary type. Cumulites occur in irregular patches 
in the areas occupied by the small spherulites, as also in other parts 
of the section. On one margin of the preparation there is a brown 
spherulitic band, the spherulites being of the microfelsitic type. 
They show very irregular dark brushes between crossed nicols, and 
the band has to some extent been broken up, small spherulites of 
the ordinary type filling the fissures (Pl. XXXII, figs. 5 & 6). 
These ordinary spherulites, which are of very small dimensions, 
together with the large brown microfelsite-spherulites and the 
lithophyse, constitute the entire rock. 

A good example of one of the large microfelsite-spherulites occurs 
in this section. The centre consists of a spherulitic aggregate 


456 MESSRS. J. PARK AND F, RUTLEY ON THE (Aug. 1899, 


which shows no distinct dark cross between crossed nicols, but 
merely a number of dark brushes, which, on rotation, inosculate, 
forming irregular kaleidoscopic patterns of black shadowy brushes on 
a brown ground. This nuclear portion is succeeded by similar but 
more elongated spherulitic growths whieh merge into arms, at 
times more or less straight, but generally curved. The latter usually 
terminate abruptly in rounded ends, but it is evident that they 
often ramify for some distance through the rock, transverse or 
oblique sections of such arms frequently occurring in the slides of 
these Omahu rocks. What may be termed the groundmass consists 
of the small ordinary spherulites of later development. Pl. XX XIII, 
fig. 2, is an ideal representation of one of the large brown micro- 
felsite-spherulites, as it would probably appear if isolated from the 
surrounding material and magnified from 10 to 20 diameters. 
Pl. XXXITI, fig. 1, gives a fair idea of the general appearance of the 
microfelsitic matter which constitutes these brown spherulites. 
The drawing represents a portion of one of the arms magnified 
1100 diameters. 

It will be seen that the microfelsitic matter is largely composed 
of hazily-defined fibres which often anastomose. They do not show 
sharp boundaries as a rule, and small scales and globulites occur in 
the fibrous mass. This microfelsite appears to be a brownish glass 
haying an ineipient and peculiar devitrification which seems to be 
incomplete." WVogelsang describes similar spherulites in the Tolesva 
rock as: “apart from the trichites, felsitically devitrified ; in the clear 
interstices there is still much homogeneous glass, although this 
appears to be obscured by granular, rusty yellow ferrite.” It would 
appear that the brown microfelsite-spherulites represent segrega- 
tions of a material differing, to some extent, chemically from the 
rest of the magma. That they were the first bodies, after the 
trichites, to separate from the magma seems uncertain, since they 
occasionally envelop crystals of felspar, but as the latter are often 
corroded it may be doubted whether they are authigenic. Be this 
as it may, there can be little question that these microfelsite-sphe- 
rulites represent the earliest portions of the magma that solidified 
as glass. At what period devitrification took place in them there 
seems also little doubt, since it denotes a rudimentary kind of 
crystalline structure of radiating character, more or less ill-defined 
in the centre of the sphervlite, as indicated by the frequent dis- 
tortion of the dark cross in the spherieal forms without arms, and 
by the very irregular brushes in the armed forms. The arms of 
these spherulites, when seen in longitudinal section, show a rude 
parallelism of the microfelsitic fibres. Fhe latter correspond in 
general direction with the trend of the arms, and in such sections 
show a rather weak double refraction. It may, however, be remarked 


1 In very thin sections of the arms of these spherulites barely any change of 
tint is perceptible when a Klein’s plate is used, especially in transverse sections 
of the arms. This seems to confirm Vogelsang’s statement that much un- 
altered glass is still present. 


2 «Die Krysialliten, 1874, p. 149. 


Vol. 55.] RHYOLITES OF THE HAURAKI GOLDFIELDS. 457 


that a similar weak double refraction, apparently due to tension,’ 
may be seen in certain bands in obsidian. The magma in 
which the microfelsite-spherulites were formed was filled with 
streams of trichites, and the fluxion-structure which they denote 
passed without interruption through the spherulites, the sub- 
sequently-developed arms of which produced no perceptible dis- 
turbance of the trichites. The later stage, consisting in the deve- 
lopment of the small ordinary spherulites, the reheating of the 
rock, its effect upon the surfaces of the microfelsite-spherulites, and 
the reduction again of already solidified portions of the lava to a 
state of fusion, followed by a final complete solidification, are points 
which have already been admirably dealt with by the late Hermann 
Vogelsang, in his description of the Tolesva rhyolite. It would 
be superfluous, therefore, to do more than allude to his masterly 
examination of a rock which so closely resembles the one now 
under discussion. 

The proof of the secondary fusion rests, according to Vogelsang, 
upon the rounding of the arms of the large spherulites and upon the 
indication by trichites of a decidedly fluid movement in the rock 
immediately adjacent. These points can all be verified in the rock 
from Omahu, in which, furthermore, the arms of the brown sphe- 
rulites often show a distinct isotropic border, fully attesting the 
superficial vitrification of these elsewhere partially devitrified bodies: 
no more ample proof of this secondary fusion could be required. A 
leading feature in this Omahu specimen is the presence of lithophyse. 
A portion of one of them is ineluded in the-thin section of this rock. 
It shows several irregular cavities bordered by reddish-brown, nearly 
isotropic matter, and tridymite. 


H, [176]. Waikino, near Waihi.—This is a small fragment 
of a pale bluish-grey rock, containing little angular pieces of pumice 
of a somewhat darker colour. These included specks and fragments 
have a distinctly vitreous lustre. The rock is rather harsh to the 
touch. Under the microscope the section is seen to be largely com- 
posed of fragments of pumice, embedded in a glassy matrix slightly 
devitrified by globulites. The devitrification is, however, only 
incipient, and both the fragments and matrix are almost completely 
isotropic. ‘The amount of matrix is so small that the rock consists 
almost exclusively of pumice-fragments. The section contains some 
corroded fragments of felspar-crystals, which appear to represent 
oligoclase and andesine, and a very few rounded fragments of 
devitrified rock of cryptocrystalline character—in one instance with 
brown, more or less glassy matter, which may be part of a micro- 
felsite-spherulite. The rock is essentially a pumice-tuff. (Pl. 
ORY 5 tie: 6.) 


H, [178]. Waikino, near Waihi.—A pale greyish-white, 
lithoidal rock, with a brownish banding, the specimen glistening 


1 “Microse. Char. of Vitr. Rocks of. Montana,’ Quart, Journ. Geol. Soc. 
yol. xxxvil (1881) p. 393, 


458 MESSRS. J. PARK AND F, RUTLEY ON THE [Aug. 1899, 


with numerous minute colourless crystals, which occasionally are 
lath-shaped and exhibit a brilliant vitreous lustre. Seen under 
the microscope, the section shows numerous porphyritic crystals 
and fragments of crystals of oligoclase and andesine, and in 
one instance a sharply-defined crystal of labradorite included in © 
another of less basic constitution. The rock has apparently been a 
glassy lava, but is now completely devitrified by globulites. It 
contains bands and irregular patches of yellowish-brown matter 
resembling microfelsite. Numerous nests of tridymite are present, 
and the section shows a delicate, but not strongly-marked, wavy 
fluxion-structure and a moderate amount of magnetite-dust. 


H,, [179]. Waikino, near Waihi.—A pale yellowish-grey or 
buff-coloured lithoidal rock, containing minute crystals, some of 
which are colourless and glassy, while others are dark green or 
black. The section, under the microscope, 1s seen to contain corroded 
porphyritic crystals and fragments of oligoclase, and occasionally of 
labradorite and andesine. ‘There are also a few fragments of crystals 
of pale greenish hornblende, but the pleochroism is extremely feeble 
or barely perceptible, and it is mainly on aceount of the extinction- 
angle that the crystals cannot be mistaken for pyroxene.” Unfortu- 
nately the slide shows no transverse section of these prisms, and thus 
the angle of intersection of the cleavages cannot be ascertained. The 
crystals are crossed by transverse fissures, as in actinolite. The rock 
itself is a lithoidal rhyolite, with rather poorly-defined corrugated 
fluxion-structure, and containing small nests of tridymite and occa- 
sional crystals and irregular aggregates of magnetite and pyrites. A 
few small rock-fragments are present in this lava. Some of them con- 
tain a large amount of vitreous matter,cften with numerous micro- 
lites and grains of magnetite. It seems probable that these small 
fragments of rock, as well as the larger fragments of crystals of the 
more basic plagioclastic felspars and those of hornblende, were 
derived from andesites. These included fragments may be perhaps 
regarded as sufficient warrant for terming the rock a tufaceous 
rhyolite, but they are not very numerons, and probably indicate a 
mere sprinkling of volcanic dust. 


H,, [181]. Waihi.— A pale greyish - white lithoidal rock, 
speckled with minute dark crystals and fragments, and with a very 
few larger dull white ones. 

Under the microscope, the section is seen to contain porphyritic 
erystals of felspar, mostly fragmentary and much corroded. ‘These 
in some instances are oligoclase, in others andesine, and occasionally 
labradorite. One or two of the more basic felspars are twinned on 
both the albite- and pericline-types. There are also some fragments 
of rock in this lava which have undergone more or less fusion on 
their boundaries. In one instance such a fragment shows, in 
ordinary transmitted light, the tolerably well-defined forms of 


1 ¢:¢= about 15°, measured from the cleavage. The mineral appears to be 
partially altered into a scaly substance, possibly tale. . 


Vol. 55. | RHYOLITES OF THE HAURAKI GOLDFIELDS. 459 


several porphyritic felspar-crystals, which, except along cracks and 
in a few irregular spots, are completely isotropic: they have, in fact, 
been fused and converted into felspar-glass, The fragment of 
spherulitic rhyolite in which these fused felspars lie has been less 
affected by the action of heat, being merely fused at the surface, 
from which a few small streamers or threads of brown glass are 
seen to emanate and to become mixed with the fluxion-streaks of 
the surrounding colourless rock (Pl. XXXIV, fig. 4). Other included 
rock-fragments are in some cases lithoidal, but the majority are 
vitreous and brown. ‘The rock in which the fragments and crystals 
already mentioned lie is essentially an obsidian with well-defined, 
wavy, corrugated fluxion-structure, but sufficiently devitrified by 
globulites to have a thoroughly lithoidal aspect in the hand-specimen. 
It is only by the darkness of the thin section between crossed nicols 
that the slightness of the devitrification can be realized. Close 
examination then shows that the section is not uniformly dark, but 
that it exhibits a nebulous milky haziness in those parts where 
cumulites occur and in those streaks in which globulites are crowded. 
The section is interesting when compared with the specimen from 
which it was cut, as showing what slight globulitic devitrification 
suffices to impart a lithoidal aspect to a glassy rock. ‘This rock is 
not a rhyolite-tuff, but it might be termed a tufaceous rhyolite 
or devitrified obsidian. 


H,, [182]. Waihi.—A pale grey lithoidal rhyolite, showing very 
small lath-like felspars with a vitreous lustre. 

In thin section under the microscope it is seen to be a devitri- 
fied rock with a corrugated or damascened fluxion-structure. It 
contains porphyritic felspars, often showing zonal structure. From 
their extinction-angles they appear in some cases to be oligoclase, 
in others andesine. Examined by Becke’s method, no felspar 
with a refraction less than that of Canada balsam seems to be 
present among the porphyritic crystals. Some crystals and grains 
of pyrites are visible. 

The rock much resembles that from which the previously-described 
section H,, [181] was made, but it has undergone much greater 
devitrification by globulites. The darkness of the section, however, 
between crossed nicols indicates that a large amount of unaltered 
vitreous matter yet remains. 


H,, [187]. Adit-level, Waihi.—A pale pinkish-white to 
eream-coloured lithoidal rock, with rather numerous dark specks. 

Under the microscope the section shows a very delicate spherulitic 
structure, which in places assumes an axiolitic character. This is 
best seen in ordinary transmitted light. Between crossed nicols it 
becomes very obscure. Occasionally a few bright spicules or 
crystalline rods of a microlitic nature may be discerned among the 
radiating isotropic fibres of the spherulites ; and that, like the fibres, 
they have an approximately radial disposition, may now and then be 
made out. These rods appear to give straight extinctions, but they 


460 MESSRS. J. PARK AND F, RUTLEY ON THE [ Aug. 1899, 


are so diminutive that it is difficult to speak with certainty upon this 
point. Under an amplification of 250 diameters the spherulites are 
seen to consist of irregularly branching fibres. In some cases 
margarites seem to be present, but there are so many globulites in 
the spherulitic aggregates that it is not easy to say how far they 
may assume any definite order. These spherulites and axiolites are 
nearly isotropic, only a faint hazy light being transmitted when 
they are viewed between crossed nicols, even when care is taken to 
exclude all extraneous light. Apparently they are microfelsite- 
spherulites. 

The section contains some porphyritic crystals, which, from their 
outlines, may safely be regarded as having once been felspars. 
There are also fragments of such crystals, but in all cases they have 
undergone alteration by fusion and may be considered as felspar- 
glass. In most instances they are perfectly isotropic, but a few 
show very feeble traces of double refraction, and two or three of the 
smaller fragments possess a microcrystalline structure. (Pl. A XXIV, 
fig. 2.) 

The evidence seems, on the whole, to show that the rock has been 
reheated, at all events to a sufficient extent to fuse the felspars. 
The lithoidal character of the rock is probably due to a later 
globulitic devitrification. The dark specks visible in the hand- 
specimen are seen under the microscope, in reflected light, to be 
crystals and irregularly-shaped patches of pyrites. 


H,,[191]. Grand Junetion Mine, 100-foot level, Waihi. 
—This is a pale greyish-white or yellowish lithoidal rock, showing 
numerous minute colourless crystals with glassy lustre. 

Under the microscope the rock is seen to be a rhyolite with 
a ypoorly-defined, irregularly-corrugated fluxion-structure. The 
lithoidal character of the rock is mainly due to globulitic devitrifi- 
cation. The section contains numerous small aggregates of tridymite, 
and many porphyritic crystals and fragments of crystals of felspar, 
which are for the most part oligoclase and andesine, but some are 
sanidine ; also an occasional crystal of labradorite may be seen in 
this section. Some of these crystals and fragments are more or less 
corroded, but most of them are so cut that measurement of their 
extinction-angles affords only an approximate clue to the nature of 
the felspars. Crystals and specks of pyrites and magnetite are 
present ; also a few small fragments of other rocks, apparently 
_ rhyolitic. An analysis made by Mr. Philip Holland is tabulated 
on p. 467. 


H,,- Waikino.—A pale bluish-grey rock with grains of quartz, 
some little dark erystals, small ochreous specks, and infiltrations of 
bluish-white opal. 

Under the microscope the rock appears to consist, apart from the 
numerous porphyritic crystals which it contains, of almost completely 
isotropic matter, and in this appear in places, when the section 
is examined in ordinary transmitted light, markings which indicate 


Vol. 55.] RHYOLITES OF THE HAURAKI GOLDFIELDS. 461 


an irregular fluxion-banding. ‘These bands are occasionally seen to 
sweep round the porphyritic crystals, a circumstance which tends to 
confirm the view that the rock is a glassy rhyolite; otherwise 
it might here and there be mistaken for a pumice-tuff. Portions of 
the section are, however, quite free from these streaks, and in such 
parts irregular perlitic cracks frequently appear and often pass into 
the porphyritic crystals, especially the quartz-crystals (Pl. XX XIII, 
fig. 3), in a manner closely resembling that described by Prof. Watts 
in his paper ‘On the Occurrence of Perlitic Cracks in Quartz,’ from 
a porphyritic pitchstone (or obsidian) occurring at Sandy Braes, 
14 mile north-east of Tardree Mountain. The specimens described 
by Prof. Watts were pitch-black, and exhibited a brightly vitreous 
or occasionally resinous lustre. Herein the Irish rock differs con- 
siderably in aspect from that now under consideration: for the 
latter is more nearly white than black, and presents scarcely any trace 
of vitreous lustre. That it has been deprived of this by merely an 
incipient devitrification is evident, for although the groundmass of the 
section appears to be isotropic when viewed between crossed nicols, 
one can, on carefully excluding all extraneous light, perceive a hazi- 
ness or milkiness pervading those parts of the section where fluxion- 
banding is most marked. When viewed in ordinary transmitted 
light, the character of this devitrification is not very clearly dis- 
cernible, but under an amplification of 400 diameters it appears 
to be microfelsitic; in other words, the devitrification is due to the 
development of fibres, scales, and some longulites and globulites. 
The more strongly-marked fluxion-streaks can be seen to be a brown 
glass, apparently more or less made up of globulites and forming small 
and irregular strings, which sometimes show feeble double refraction 
when lying at 45° to the principal sections of the crossed nicols. 
It is interesting, in connexion with the occurrence of opal in this 
rock, that Prof. Watts mentions the not unfrequent deposition 
of opal in a greyish-green variety of rhyolite from Connor, Sandy 
Braes.”. It may be that heated water, charged with alkaline 
silicates, accounts to some extent for the development of perlicity 
in quartz; and, considering the prevalence of not springs in New 
Zealand, it seems by no means unlikely that they may have had 
some influence in the devitrification of glassy rocks in their vicinity. 
The ‘ quartz-blows’ mentioned by Mr. Park,’ which are alluded to 
on p. 463, may be due to a like cause. 

Besides quartz, the other porphyritic crystals in the rock here 
described appear to be chiefly oligoclase, andesine, and labradorite. 
Pyrites is also present in small quantity. One or two specks of this 
mineral occur in a porphyritic crystal which has a reddish-yellow 
colour in transmitted light, but in reflected light appears white, 
and is probably kaolinized felspar. 


H,,. Waihi.—A pale yellowish-grey lithoidal rock, with numerous 
dark micaceous-looking crystals, mostly about =, inch in diameter, 


1 Quart. Journ. Geol. Soe. vol. 1 (1894) p. 367. ? Ibid. p. 368. 
3 «The Geology & Veins of the Hauraki Goldfields,’ 1897, p. 101. 


462 MESSRS. J. PARK AND F, RUTLEY ON THE [Aug. 1899, 


Apart from porphyritic crystals, the rock is seen under the micro- 
scope to consist almost exclusively of very small spherulites. When 
viewed in ordinary transmitted light the section appears mottled 
with feebly translucent flocculent matter, while in reflected light 
these mottlings look nearly snow-white, and they are apparently 
due to partial kaolinization. 

The porphyritic crystals are chiefly sanidine, quartz, and biotite; 
while diminutive crystals of magnetite are sprinkled throughout the 
rock as a fine dust. The porphyritic crystals are more or less 
corroded. ‘The crystals of biotite vary considerably in dimensions, 
and occasionally present ragged boundaries (Pl. XX XIII, fig. 7). 
biotite-rhyolites from other localities in New Zealand have been 
described by Capt. F. W. Hutton,’ the late Mr. R. Daintree,’ and 
others. Curious crystallites, similar to those described by Vogelsang 
as occurring in a rock from Theresienhtgel, at Tarezal, near Tokay, 
are to be seen in this biotite-rhyolite from Waihi, and some of 
them are represented in Pl. XX XIII, fig. 6. 


H,,- Mataura.—A deep violet to blackish rock with very small 
crystals of vitreous lustre. Delicate, rudely-parallel, but irregular 
bands of pale greyish to slightly reddish colour traverse the speci- 
men. The cut surface exhibits a good lustre, almost a polish. 
The specimen is weakly but distinctly magnetic, and is so hard that 
the point of a knife-blude makes no impression upon it. The rock 
might pass for jasper. 

Under the microscope, in thin section, which, however, is not 
very translucent, the rock seems to be possibly a rhyolite with 
fluxion-banding. ‘The less translucent bands appear so dark be- 
tween crossed nicols that the presence of much almost unaltered 
glass is suggested, while in ordinary transmitted light, that is, in 
as much light as thin parts of the section will transmit, the bands 
seem to consist of densely-packed globulites. 

In a paper read before this Society in 1891,° I had occasion to 
allude to a specimen of obsidian collected by my friend, Mr. G. F. 
Rodwell, from the crater of Vulcano, at a point whence a strong 
jet of steam was then issuing, and which had apparently com- 
pletely or almost completely devitrified the obsidian through the 
development of globulites. It seems quite possible that this rock 
from Mataura has undergone a like devitrification, bnt that in this 
instance a silicifying process has also taken place, which would 
account for the hardness and jasper-like character of the rock. The 
section contains numerous porphyritic crystals, which from their 
extinction-angles appear to be sanidine, oligoclase, andesine, and 
possibly still more basic plagioclase. These felspars seem fresh, and 
are in no instance represented by vitreous matter, hyalomorphs, 
if one may venture to coin the name for vitrified felspars, such as 
those from Waihi, described on pp. 459-60. It would seem that 


1 «The Eruptive Rocks of New Zealand,’ Proc. Roy. Soc. N.S.W. vol. xxiii 


(1889) p. 116. 
2 Trans. N.Z. Inst. vol. vii (1874) p. 459. 
3 «On a Spherulitic & Perlitic Obsidian from Pilas, Jalisco,’ Quart. Journ. 


Geol. Soc. vol. xlvii (1891) p. 582. 


Vols 5; | RHYOLITES OF THE HAURAKI GOLDFIELDS. 463 


the felspars from Waihi have undergone a dry fusion, while these 
in the rock from Mataura have probably been subjected to the 
action of steam. ‘The rock contains minute crystals of magnetite, 
apparently a considerable amount of tridymite, and possibly some 
pyrites. 


H,,. Waihi.—A rock too hard to be scratched by steel, and con- 
sisting of rather dark and lighter bands of bluish-grey, chert-like 
material. ‘The specimen has a subconchoidal fracture, and is 
translucent on thin edges. The cut surface, from which the thin 
section was sawn, has taken a brilliant polish, more so, indeed, than 
that of the silicified rhyolite from Mataura, last described. This 
specimen is from one of the ‘ quartz-blows’ described by Mr. James 
Park as ‘covering an area of several acres,’ and often standing 
6 or 8 feet in height.’ 

Under the microscope the section is seen to consist essentially of 
chalcedony, with some opaque white grains which may be kaolin, 
and fragments of a brown, vesicular, glassy lava(Pl. XX XIII, fig. 4). 
There are also numerous long, thin, brown, hair-like streaks in 
the section. At first one might be disposed to regard them as very 
irregular cracks in the chalcedony, stained, or occasionally filled, 
with minute granules of limonite, but their lash-like character 
and the apparent absence of any approximate parallelism or lines 
intersecting at right angles seem to negative the supposition that 
they are cracks. The question is whether they represent any 
organic structure. ven what, in the absence of more precise and 
special knowledge, have here been provisionally termed fragments 
of brown, vesicular, glassy lava, might possibly, in the eyes of a 
paleontologist, be recognized as the chalcedonic vestiges of some 
organism. ‘They have been compared with sections of the vesicular 
glassy basalt-lavas or tachylyte of the Sandwich Islands, but in the 
latter the vesicles are usually much larger, while the olivine- 
crystallites, so prevalent in the Honolulu rocks, are absent in these 
fragments. Whether the material of this so-called ‘quartz-blow ’ 
was brought from below and deposited from heated water charged 
with silica (and the section in pl. xiv of Mr. Park’s ‘Geology & 
Veins of the Hauraki Goldfields’ seems to indicate such a possi- 
bility) there is no distinct evidence to prove, and it appears 
safer, so far, to refrain from any such conjectures. Whatever 
interpretation may be put on the included fragments, their general 
appearance is fairly indicated in Pl. XX XIII, fig. 4. 


H,,. Waihi.—A_ bluish-grey rock, mottled with deep reddish- 
brown. ‘The fracture is subconchoidal, and the lustre feebly sub- 
vitreous. ‘his specimen is also stated to have been derived from 
a ‘ quartz-blow.’ 

Under the microscope, the thin section appears to consist of 
fragments of an altered eruptive rock cemented with chalcedony, 
The fragments of rock are probably those of an andesite, although 

no ferromagnesian minerals are to be recognized in them, any 


1 «The Geology & Veins of the Hauraki Goldfields,’ 1897, p. 101. 


464 MESSRS, J. PARK AND F, RUTLEY ON THE [Aug. 1899, 


which may have: been present having apparently been converted 
into limonite. A few small felspars give extinction-angles suggestive 
of anorthite, but they are much altered. The larger porphyritic 
felspars are represented by pseudomorphs of chalcedony. Pyrites 
is present in these rock-fragments in very considerable quantity, 
forming irregular patches, aggregates of crystals, minute individual 
crystals, or mere specks. Some small crystals of magnetite are also 
to be seen. On the whole, the rock appears to be an andesite- 
tuff, very greatly affected by solfataric action. 


H,,- Waihi.—A compact bluish-grey rock, containing numerous 
small crystals with a vitreous lustre. The specimen shows a cavity 
about 2 inch in diameter, lined with mammillated chalcedony and 
with some snow-white crust. The cut surface takes a high polish. 
This specimen is stated to come from a ‘ quartz-blow.’ 

Under the microscope the rock does not appear to be clastic, as 
in H,,, but to be an altered andesite, which, however, like the 
preceding, has been highly impregnated with silica. It contains 
numerous porphyritie crystals of andesine, labradorite, and occa- 
sionally anorthite. Some of these are honeycombed with irregular 
inclusions, containing devitrified glass (Pl. XX XIII, fig. 8). Brown 
spherulites are also present, and large brown spherulitic growths 
sometimes occur as borders around groups of felspar-crystals. More- 
over, porphyritic quartz showing a rude perlitic structure, similar 
to that described by Prof. Watts, may be seen in this section. 


Appendix. 


Since fragments of andesite and minerals, in many cases doubtless 
derived from andesitic tuffs, occur in the rocks which form the 
subject of this paper, it may be well to add a brief description of a 
few of these andesites from Waitekauri. Although many New 
Zealand andesites have been described by Capt. Hutton, those from 
Waitekauri do not seem to have been specially noticed. 


H,, [192]. Waitekauri.—A pale bluish-grey rock, with por- 
phyritic quartz and numerous blackish-green crystals. 

Under the microscope, the groundmass of the section presents a 
hypocrystalline character, which, from the presence of microlites, 
occasionally becomes almost hyalopilitic. This groundmass is 
plentifully charged with globulites, and contains a few tolerably 
large, rounded, porphyritic crystals of quartz, one of which gives a 
good positive uniaxial figure in convergent light. The rock also 
contains porphyritic crystals of plagioclastic felspars and pseudo- 
morphs of hematite after hornblende, transverse sections of the 
latter sometimes giving the prismatic angle of 125°. The felspars 
are oligoclase and andesine. Small opaque pseudomorphs, appa- 
rently after mica, are plentiful in the section. Little crystals of 
zircon and magnetite are also present. The rock appears to contain 
some tridymite. It is essentially a hornblende-andesite. 


Wola s| . RHYOLITES OF THE HAURAKI GOLDFIELDS. 465 


H,, [194]. Waitekauri.—A pale grey rock with dark green 
or blackish crystals, resembling 192, but of somewhat paler colour. 

Under the microscope this rock shows a microcrystalline ground- 
mass with some brown devitrified glass. Numerous porphyritic 
erystals of oligoclase and andesine are present, often with well- 
marked zonal structure. Pseudomorphs of hematite after hornblende 
also occur porphyritically. There are, moreover, a very few small 
erystals of biotite, sometimes only represented by pseudomorphs. 
Small cubes and grains of pyrites occur in this section, while 
here and there irregular vesicles may be seen, filled with chlorite 
in fan-like groups of crystals. This rock, like the preceding, is a 
hornblende-andesite. 


H,, [195]. Waitekauri.—aA rather dark-grey, compact rock, 
with numerous blackish-green spots and a few very small dark 
erystals which have a brilliant lustre. 

The section shows a microcrystalline groundmass with numerous 
porphyritic crystals, mostly of labradorite, porphyritic crystals of 
altered pyroxene, and specks of pyrites; some of the pyroxene may 
be rhombic, but the alteration does not admit of a definite conclusion 
upon this point. The rock may be regarded as an altered 
augite-andesite. 


H,, [196]. WaitekauriaA rather dark-grey compact rock 
with numerous small, lath-shaped, colourless crystals, having a 
vitreous lustre, and some small dark green or blackish crystals. 

The section shows a crystalline granular groundmass, with 
many felspar-microlites. In this occur porphyritic crystals of 
felspar and hornblende, the former somewhat corroded. From their 
extinction-angles they may in some cases be referred to labradorite, 
in others to andesine. The hornblende-crystals are mostly frag- 
mentary. Magnetite and some small specks of pyrites are present. 
The rock is a hornblende-andesite. 


Summary. 


Reviewing the rhyolites of the Hauraki Goldfields, they are 
found to present many points of interest, and to supply examples of 
almost every structural peculiarity known among rocks of this class, 

Perlicity appears to be of rare occurrence, even in the obsidians, 
but although many of the lithoidal rhyolites possibly assumed that 
character on solidification, there are others which doubtless became 
lithoidal through subsequent devitrification and, in a large number, 
comparatively unaltered or quite fresh vitreous matter is still 
present. 

Reheating of already solidified lavas has heen, as we have fre- 
quently had occasion to remark, a by no means uncommon feature 
in the history of these rhyolites, and in some cases the temperature 
has been sufficient to render felspars isotropic: in other words, to 
reduce them to the condition of felspar-glass,' 

1 Descriptions of somewhat analogous cases may be found in M. A, Lacroix’s 
work, ‘Les Enclaves des Roches Volcaniques,’ 1893. 

@75.G. 5. No. 219. 24 


466 "MESSRS. J. PARK AND F, RUTLEY ON THE [Aug. 1899, 


Another interesting point with regard to the Hauraki rhyolites 
is the general preponderance of plagioclastic felspars 
among the porphyritic crystals, which might almost induce 
one, at first sight, to regard them as allied to dacites. Mr. Philip 
Holland's analyses, however, seem to indicate that the series is rhyo- 
litic, and it is quite possible, and in some instances almost certain, 
that some of the more basic porphyritic crystals are derived from the 
andesitic rocks which occur so plentifully in the neighbouring districts. 

It is also interesting to note the silicifying effects of hydro- 
thermal agency upon some of the rocks, and that this does not 
merely bring about the cementing of tufts, but seems also to affect 
solid lavas in a very marked manner. The analysis of some of 
these rocks would probably show an abnormally high percentage of 
silica, as in the case of an altered rhyolite collected by W. H. Weed 
at Iron Pot, Lower Basin, which on analysis by J. E. Whitfield 
ylelded as much as 89:2 per cent. of silica.* Such super-silicification, 
if met with in any of our ancient rhyolites, would go far to prove 
the former presence of hot silica-bearing springs in this country. 

In describing the rhyolites of Omahu, considerable space has been 
devoted to the branching spherulites which they contain. This 
has been done, partly on account of the interest attaching to these 
bodies, partly in order to give, if possible, a clear account of the nature 
of the microfelsitic matter of which they are composed. That these 
spherulites consist of an imperfectly-devitrified glass has been 
indicated by Vogelsang when describing similar spherulitic struc- 
tures in the rhyolite of Tolesva, and from an examination of the. 
rhyolites of Omahu it has been possible not cnly to verify all that 
Vogelsang has written about the Hungarian spherulites, but what 
Rosenbusch has stated regarding the nature of microfelsite.”? This, 
it appears, is a convenient name for a rudimentary form of devitri- 
fied glass. The devitrification consists in the development of 
something resembling fibrous structure, but these so-called fibres, 
when highly magnified, have the appearance of imperfectly-defined 
strings of margarites, with an occasional tendency to assume a longu- 
litic aspect. Among these fibres, which frequently assume an approxi- 
mately parallel arrangement, there often lie some small irregularly- 
shaped filmy scales, almost suggestive of tridymite. Globulites 
and trichites may also be present. The latter, however, do not 
appear to be essential constituents of the microfelsite, but rather 
independent developments. 

It has been questioned by some petrologists whether the term 
microfelsite be worthy of retention; but, if rightly understood, 
it appears to be of value in denoting a phase of devitrification, not 
adequately to be expressed by any other name current in petro- 
graphy, while its abandonment would produce a gap which could 
be bridged only by much circumlocution. 

Within the limits of this paper it would scarcely have been 
possible to do justice to the many observers who have treated of the 

1 « Analyses of Rocks & Analytical Methods,’ Clarke & Hillebrand, Bull. U.S. 


Geol. Surv. 1897, No. 148, p. 132. 
? ‘Mikroskop. Physiogr.’ 3rd ed. vol. ii (1896) pp. 583-594 e¢ segg. 


. 
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Vol. 55. ] RHYOLITES OF THE HAURAKI GOLDFIELDS. 467 


microscopic characters of the ‘ Eruptive Rocks of New Zealand,’ 
but the paper by Capt. Hutton, bearing that title, is replete with 
references to their works up to 1889, and during the past ten years 
much has been added to this branch of geological literature. 


Part IJ].—Awnatysers of the Ruyorires. By Paine Hortanp. 


The rocks H, from Omahu and H,, [191] from Grand Junction 
Mine, 100-foot level, Waihi, both of them described in this paper 
(pp. 451 & 460), have been analysed. Moreover, analyses of three 
rhyolites from the United States, copied from Bull. No. 148, U.S. 
Geol. Surv. pp. 131 & 192, are placed beside these analyses of 
Hauraki rhyolites for comparison, since in some respects they closely 
resemble them. Nos. III & IV are by W. F. Hillebrand, and 
No. V by J. E. Whitfield. 

No. III is the analysis of a rhyolite a short distance north- 
west of Willow Lake, near the Geyser, Plumas County, California. 
No. IV is that of a rhyolite from near Slate Creek, west of 
Deer Creek Meadows, California. No. V is of a rhyolite from 
Mount Sheridan. 

A small amount of biotite is stated to be present in No. IV, and 
a little augite in No. V. 

In Nos. I & II the finely-powdered rock was dried at 100°C. 
before analysis, and in Nos. III & 1V the materials were dried at 
HLOS C. 

In the Hauraki rhyolites (Nos. I & II), a very small amount of 
pyrites was detected under the microscope. 


1 i EL ELM. EY. Y. 


Willow Slate Mount 
Omahu. Waihi. Lake. Creek. Sheridan. 


SiO, Siltea ....2..-+07> PIEOD eect 7308 424 [364 75°89 
Al,O, Alumina ...... P25 sce; 1350 1450 13°44 12:27 
Fe,O, Ferric oxide... 6 acaacs 260) 6 20 ‘60 1-12 
FeO Ferrous oxide... none ...... 13 ‘67 YG: 1:37 
WAS ee a trace ...... trace "06 06 none 
TiO, Titanic oxide... 5 ere 62 “20 ut “50 
CaQ@ Lime ots.05..5... ols apa 1:07 “11 1:26 86 
SrO Strontia 02 

BaO Baryta ......... SLO... ese O 18 sat — 
MgO Magnesia ...... Gi owame 15 "25 ‘26 “29 
K© Potash .......... SEU) | aeenee 3°19 3°66 4°50 3°42 
Na,0 Soda ...........- P2330 An 3°95 3°00 3°51 3°23 
Li,0 Lithia -01 

P.O; Phosphorus | trace ...... trace ‘07 ‘06 none 

pentoxide wees 12 ‘0 “6 
siiicnignarteibsids 71 : oo, genet ole 
HO Water..........2. Wot... 1:33 2°04 1-99 "82 
100:10 99:30 10028 10030 100-06 
Specific gravity =2°511. =2°514. 


[In Analyses I & II strontium and lithium were not sought. ] 


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468 


MESSRS. J. PARK AND F. RUTLEY ON THE [Aug. 1899, 


EXPLANATION OF PLATES XXXI-XXXTV., 
Prats XXXII, 


Geological Sketch-map of the Hauraki Goldfields, on the scale of 8 miles to 
the inch. 


Fig. 1. 


Hig. 1: 


os fo OS 


Puate XXXII. 


H,. Mercury Bay.—Obsidian banded by longulites and trichites. A 
small brown spherulite is shown on the left of the field. x 18. 
Ordinary light. (See p. 454.) 


. H;. Mercury Bay.—Spherulitic and perlitic obsidian. The brown 


microfelsite-spherulites are, in places, quite spherical, in others poly- 
gonal. In polarized light the dark crosses separate, in some cases as 
in the interference-figures of biaxial crystals, in others the crosses 
show irregular distortion as in the figure. Xx 18. Nicols crossed. 
(See p. 454.) 


. H;. Mercury Bay.—Portion of the preceding section, showing perlicity 


in the lower and large brown spherulites in the upper and left-hand 
parts of the field. x 30. Ordinary light. (See p. 454.) 


. H,. Omahu.—Spherulitic rhyolite, showing transverse sections of the 


arms of microfelsite-spherulites. x 30. Ordinary light. (See 
p. 453.) 


. H, [109] Omahu.—-Spherulitic rhyolite, showing transverse sections of 


the arms of a microfelsife-spherulite, the dark isotropie borders 
proving the superficial fusion of these bodies. Smaller spherulites 
of the ordinary type and of a second generation occupy the spaces 
between these arms. x 45. Nicols cros:ed. (See p. 455.) 


. H, [109] Omahu. A brown microfelsite-spherulite, showing the body 


and portions of the arms. The spaces between the arms are minutely 
spherulitic. These spherulites are of the ordinary kind, and have 
been developed subsequently to the superficial fusion of the microfelsite- 
spherulites. X18. Nicols crossed. (See p. 455.) 


Puate XXXII. 


H, [109] Omahu.—That part of the drawing below the line mm 

. represents a portion of one of the arms of a microfelsite-spherulite in 
‘longitudinal section, and conveys a fair idea of the appearance of the 
microfelsitic matter. > 1100. Ordinary light. (See p. 456.) 
Diagrammatic representation of an isolated microfelsite-spherulite of 
the armed type. (See p. 456.) 


. H,;. Waikino.—Perlicity in quartz of rhyolite. 18. Ordinary light. 


‘(See p. 461.) 


. H,,. Waihi.—Fragments of brown glassy vesicular lava in chaleedony 


(‘quartz-blow’). x 140. Ordinary light. (See p. 463.) 


. H,. Omahu.—Trichites composed of globulites, in rhyolite. x 250. 


Ordinary light. (See p. 453.) 


. H,,. Waihi.—Crystallites in rhyolite. Xx 250. Ordinary light. (See 


p. 462.) 


. H,,. Waihi.—Portion of a crystal of biotite in biotite-rhyolite. x 30. 


Ordinary light. (See p. 462.) 


. H,,. Waihi.—Glass-enclosures in a crystal of andesine, in andesite 


altered by solfataric action. X 30. WNicols crossed. (See p. 464.) 
PuaTe XXXIV. 


. H, [6] Omahu.—Spherulitic rhyolite, showing fluxion from secondary 


fusion around portion of an arm of .a microfelsite spherulite which 
enters the field on the upper right edge. Part of a small nest of tridy- 
mite is shown on the lower right edge of the field. x 140. Ordinary 
light. (See p. 435.) : 


. H,, | 187] Adit-level, Waihi.—Isotropic felspars in a fragment included 


in.rhyolite. The structure of the latter is partly spherulitic, partly 
axiolitic. The felspars in the fragment are reduced to the condition 


Quart. Journ. Geol. Soc. Vol. LY Fl XXXII. 


F'.Rutley del. Parker & Perey lith.et imp. 
RY Old hh S OF Mirnci Ry 


BAY ANID OMAHU, N.Z. 


Quart. Journ. Geol. Soc. Vol. LV) P1 XXXIIL 


F. Rutiley del. Parker & Perey lith. et ump. 


RHYOLITES & OF THE HAURAKI GOLD-FIELDS, N. Z. 


PLXEXIV, 


TENE 


1. 


Quart. Journ. Geol. Soc. Vo 


Parker & Percy lith. et imp. 


S OF OMAHU, WAIHI AND WAIKINO, N.2Z. 


F.Rutley del. 


REYOLITE 


aaa 


BM, 


Vol. 55. ] RHYOLITES OF THE HAURAKI GOLDFIELDS, 469 


of felspar-glass through secondary heating. They appear dark in all 
azimuths between crossed nicols. ‘The spherulites and axiolites which 
constitute the enclosing rhyolite have also been rendered isotropic 
through the same cause. X75. Ordinary light. (See p. 460.) 

Fig. 3. H, [6] Omahu.—Rbhyolite, showing portions of the arms of a micro- 
felsite-spherulite traversed by fluxion-streaks. x 30. Ordinary light. 
(See p. 455.) 

4. H,, [181] Waihi.—Fused edge of a section of a fragment of spherulitic 
rhyolite, containing isotropic crystals of felspar and brown microfelsite- 
spherulites. Part of the fragment is shown on the left of the field, 
containing a porphyritic crystal of felspar, which has been rendered 
isotropic by secondary fusion. The brownish glass resulting from the 
superficial fusion of the fragment is seen to have run in irregular 
threads, which have mingled with the surrounding colourless glass of 
the enveloping rhyolite. x 30. Ordinary light. (See p. 459.) 

5. H,. Omahu.—Spherultic rhyolite, the spherulitic bands imcluding 
patches consisting of quartz with crystals of felspar (sanidine and 
oligoclase) and small octahedra of magnetite. x 30. Ordinary light. 
(See p, 451.) 

6. H, [176| Pumice-tuff, Waikino, near Waihi.—The figure shows frag- 
ments of pumice, the steam-pores in one fragment following a direction 
different trom those in another. x 75. Ordinary light. (See p.457.) 


Discussion. 


The Rey. J. F. Braxe said that he was much interested in the 
rocks last-mentioned by Mr. Rutley, namely, mushroom-like masses 
of quartz-rock, which reminded him of the quartz-knobs of Anglesey; 
also the silicified andesites, which recalled the rock of Treffgarn. 
He hoped that further particulars of these rocks would be forth- 
coming. 

Mr. Rortey briefly replied to the previous speaker’s remarks, and 
stated that he hoped at no very distant period to examine additional 


specimens of Hauraki rocks which had been affected by solfatariec 
action. 


470 MR. J, B. HILL ON PROGRESSIVE METAMORPHISM _ [ Aug. 1899, 


31. On the Progressive Metamorpuism of some DatRapian 
SeprmeEnts in the Reeion of Locu Awn. By J. B. Huu, Esq., 
R.N., of the Geological Survey. (Communicated by Sir A. 
GurxiE, D.Sc., LL.D., F.R.S. Read May 24th, 1899.) 


[Map on p. 472.] 


Contents. 

Page 

Tf. Introductory. Remarks... 5.3) ben. weds. 0ngedeneenencsyes mod eain nee 470 
II, Position of the Rocks in the Highland SOQLICS:..\.cs0s benches 471 
III. Description of the Ardrishaig Series and the Loch Awe Series 473 
IV. The Intrusive Igneous Rocks of the Area.................se0ceee 476 
V. Evidence of Progressive Metamorphism ..................e000e: 480 
Vil Conclusions i..37 secsteteneamee sees tee ss MsSotsncouaa tc eee eee 491 


I. Inrropuctory REMARKS. 


In the course of the geological survey of the Loch Fyne and Loch 
Awe districts of Argyllshire, a comparatively unaltered series of 
rocks was discovered by the author, located in a zone of which 
Loch Awe forms a central axis. So markedly different in con- 
dition were they from the ordinary mica-schists of Argyllshire 
that for some years they were looked upon as considerably later 
in age than the more crystalline rocks lying to the north and east 
of them. As the survey of the district progressed, especially in a 
north-easterly direction, a change of character was detected in them. 
They assumed a more crystalline condition ; in some areas a gradual, 
in others a more marked and rapid change of character was observed. 
In the years 1892 and 1893 it was found that these rocks, as they 
approached the more mountainous districts of Argyllshire, between 
Beinn Buidhe and Ben Cruachan, became more highly crystalline, 
until at last they were traced passing into highly crystalline schists 
of the normal Central Highland type. 

The results of these observations were briefly set out in the 
Annual Report of the Director-General of the Geological Survey for 
the year 1893. on p. 265 of which the present author’s work is 
referred to as follows :— 

‘Not less important in its bearing upon the origin and sequence 
of the Highland rocks is the recent work of Mr. J. B. Hill in the 
district of Loch Awe, to which reference was made last year. In 
the course of a recent tour of inspection I took occasion to visit Mr. 
Hill on his ground, and to examine with him the evidence which he 
has adduced as to the cessation, or at least the remarkable diminu- 
tion, of metamorphism, as the rocks are followed from the north-east 
into the basin of Loch Awe. Iwas completely satisfied that he has 
established this statement. I found that in passing westwards we 
gradually recede from thoroughly schistose rocks, and reach a 
group of shales and phyllites with bands cf limestone, hardly more 


Vol.’ 55. IN THE REGION OF LOCH AWE. £71 


altered than portions of the Silurian series of the South of Scotland. 
As might be expected, however, the diminution in metamorphism, 
though generally progressive, is not uniform, some zones, owing 
doubtless to their chemical composition, haying been less affected 
than others above and below them.’ 

It is proposed in the present paper to describe, in a little more 
detail, the phenomena which have been set forth in the above report, 
or, in other words, to prove that a great group of rocks 
which extend across the greater part of the Scottish 
Highlands, in the condition of typical crystalline 
schists, pass along their strike into rocks scarcely more 
altered than many Paleozoic sediments. So far as the 
author is aware, no previous observer has described these rocks. 


II. Posrrton or THE Rocks IN THE HIGHLAND SERIES. 


Before describing these rocks it will be convenient here to give 
a brief account of their position in the Highland series. 

In the Survey memoir on the Geology of Cowal, by Messrs. 
Gunn, Clough, and myself, published in 1597, we described in con- 
siderable detail the geology of that part of Argyllshire which lies 
between the Firth of Clyde and Loch Fyne. The district dealt with 
in this paper is a still further prolongation in a north-westerly 
direction of the Cowal district which it adjoins. As Sir A. 
Geikie states in the preface of that memoir, the Cowal district 
‘embraces the south-western extension of the various bands of 
metamorphic rocks which form the southern edge of the Highlands. 
Originally most of the rocks’ described in the memoir ‘ formed a 
thick series of sedimentary deposits, the geological age of which still 
remains to be determined. These strata have been found to have 
undergone a remarkable series of repeated movements. After being 
thrown into folds and having been cleaved so as to acquire a first 
system of deformation, they have again suffered a repetition of the 
process more than once. They consequently present secondary and 
tertiary, perhaps even quaternary, structures probably due to 
mechanical movement with accompanying recrystallization. The 
regional metamorphism thus produced is not uniformly distributed, 
but seems to increase in intensity both from the south-east and 
north-west towards a central line, ranging about north-east and 
south-west, which is an anticline of the foliation. It has not 
been traced to any intrusion of igneous rock, and is so general 
and diffused that it can hardly be regarded as in any sense a 
contact-phenomenon.’ In the memoir just quoted we pointed out 
that the rocks described in the district embraced various schist- 
bands traversing the region in a north-east and south-west direction. 
Starting from the schist boundary-fault and proceeding in a north- 
westerly direction, we first pass over a group of phyllites and pebbly 
grits with an average breadth of outcrop of 1 mile. Farther north- 
west, a grauwacke-schist with an outcrop of less than 3 mile comes in. 
This is succeeded by the Dunoon Phyllite Series, with subordinate 


Sketch-map 
of the district of | 
LOCH AWE, 
By ¥.B.Hill, R.N. | 
(( Scale 8 miles =1 inch. | 


SS SSS = 
Kilmartin= 


tli 


TA 


fi 


(ese 


@ 
> ff < 


BOVOOOSMH 


| 


“o> 


: 


G 


x 


} Various divisions of Dalra- 
dian Schists between the 


Loch Awe MMs ss Ardvishaiy series and the 
eS ee series ——— 


BS Highland border. Not differ. 


Volcanic Rocks of .Lorne. » (eax entialed on this sketch-map. 
Lower Old. Red Sandsténe Granite 


Note.—The large arrows indicate the directions of diminishing metamorphism; 
the shorter of these indicate rapid change, and the longer slow change. The 
small arrows represent inclinations of limbs of folds, and in some cases folia- 


tion. ‘The area west of the points of the large arrows is the comparatively 
unaltered area. 


lavAS 


Vol. 55.] PROGRESSIVE METAMORPHISM IN LOCH AWE DISTRICT. (e 


schistose grits and limestones, with a breadth of about 14 mile ; next, 
a series of chlorite-epidote schists, generally pebbly. North-west 
there is a zone, 7 miles broad, of schistose grauwackes, phyllites 
and albite-schists. This is the zone where, as we approch an anti- 
clinal axis of foliation, an increasing amount of metamorphism is 
met with, decreasing again as we recede from this axis in a north- 
westerly direction. After this wide zone we find another set of 
chlorite-epidote schists. This zone is succeeded by the Loch Tay 
Limestone, which is the most definite of all the sedimentary schists 
of the district. After this we get a series of thin banded mica- 
schists, generally garnetiferous. Finally we find, as we approach 
Loch Fyne, the broad Ardrishaig Phyllite Series with subordinate 
guartzose schists and limestones. 

The Ardrishaig phyllites and the beds which succeed them to the 
north-west are described in this paper, but it is not proposed to 
enter into a description of the foldings and structures set up in 
them, as this would be largely a repetition of what has been already 
fully discussed in dealing with the south-eastern extension of the 
district in Cowal. 


ILI. Descrirrion oF THE ARDRISHAIG SERIES AND THE 
Locu AWE SERIES. 


The two great groups of rocks entering into the structure of the 
region now to be described are :— 

(1) The Ardrishaig Series (consisting mainly of phyllites 
and fine-grained quartzites) and 

(2) The Loch Awe Series (consisting mainly of black 
slates, limestones, grits, and quartzites). 

The Ardrishaig Series occupies a strip of country on both sides of 
Loch Fyne. From Ardrishaig the series extends north-eastward 
along Loch Fyne, passing Inveraray, Beinn Buidhe, and sweeping 
past the western flank of Beinn Laoigh into Perthshire. 

The Loch Awe Series occupies a position immediately to the 
north-west of the Ardrishaig Series. It occurs mainly in the Loch 
Awe basin, and follows the north-easterly strike of the Ardrishaig 
Series lying to the south-east. 

The evidence of progressive metamorphism is obtained as the 
observer passes north-eastward. 

I will first of all notice the lithological characters of the rocks in 
their least altered form; and afterwards, the changes that they 
have undergone in their passage into crystalline schists. 

The Ardrishaig Series, where least altered, consists of :— 


(a) Greenish phyllites, very soft, scratching easily with the nail ; 

(6) Fine-grained greyish quartzite; and 

(c) Thin limestones, greyish to white, weathering rusty brown. 
_ They are typically illustrated at Ardrishaig, where they were 
first mapped, hence their name. A more detailed description of 
them will be found in the Survey memoir previously quoted. 


474.  =MR.J, B. HILL ON PROGRESSIVE METAMORPHISM [Aug. 1899, 


The Loch Awe Series where least altered consists of — 


(a) Limestone ; 
(6) Black slate (sometimes graphitic) ; and 
(c) Grits and quartzites. 


The limestone is very variable in character, and is intimately 
associated with the black slates into which it sometimes insensibly 
passes. It is usually crystalline, and in its most normal condition 
is blue. Dark crystals of calcite are often very numerous, giving the 
limestone a dark hue. Pebbles of blue quartz and pink felspar are 
very commonly scattered through it ; they are sometimes so abundant 
that the rock passes into a grit, with a calcareous matrix. These 
pebbles of quartz and felspar attain sometimes a length of 1 inch, 
but this is exceptional. The limestone occasionally contains pebbles 
up to 6 inches in length, of limestone or slate. At times the lme- 
stone is exceedingly fine-grained and compact, but in these fine- 
grained compact beds pebbles of quartz may often be seen. 

The black slates are nearly always found in association with the 
limestone ; they may occur above, or below, or in the limestone, and 
sometimes, by becoming gradually more calcareous, pass into the 
limestone, so that no line can be drawn where the limestone ends 
and the slates begin. They have in many cases been quarried for 
roofing-slates, and are occasionally graphitic, sufficiently so to soil 
the fingers. 

The grits immediately succeed the black slates. They are com- 
posed of pebbles of quartz and felspar, a large proportion of the 
former being of the clear blue variety, while some of the felspar- 
pebbles are pink, others being dull white. As a rule, the quartz- 
pebbles preponderate largely over the felspar. Ooarser and finer 
pebbly beds rapidly alternate, and there are occasionally zones so 
coarse in character as almost to deserve the name of conglomerates, 
grit-zones of 2 or 3 up to 12 yards wide being composed of 
pebbles of the size of almonds. ‘The grits contain pockets of black 
slate up to a foot or more in length; the pockets are flattened, 
and are seldom more than an inch thick. Partings of black slate 
are also common in the grit-bands. These pockets and black-slate 
partings are identical in character with the black slates already 
described. The intercalations and pockets of argillaceous material 
are characteristic of the grits in the Loch Awe Series. 

Finer-grained grits and grey quartzites are associated with 
the coarser grits, these quartzites and fine grits containing the same 
pockets and intercalations of blaek slate as those already described. 

Some of the grits are greenish, on account of the presence of 
minute scales of chlorite. This chloritic matter, which has given the 
prevailing green colour to the Ardrishaig phyllites, may sometimes 
pervade the slates of the Loch Awe Series, and where free from 
carbonaceous material has induced a green colour on them, instead 
of the prevailing black and blue tint. ‘The grits, however, may be 
greenish, while the slate-partings are dark blue, or even black. 

In their least altered state, the condition of the Loch Awe grits 


Vol. 55. ] IN THE REGION OF LOCH AWE, 475 


varies considerably, but it may be stated generally that even in their 
most altered condition the clastic nature of the rock is always 
evident, and the alternations of bedding due to differences of texture 
are apparent. The smaller pebbles may, however, be considerably 
crushed and granulitized, and the larger grits show flattening and 
drawing out. In some instances nevertheless, they appear to have 
hardly suffered at all, microscopic examination failing to detect 
signs of crushing. They seldom fracture along definite planes like 
ordinary schistose rocks, and mica is not common in them. When 
it occurs it is never in sufficient quantity to alter the gritty nature of 
the rock, nor to form planes along which the rock willsplit. When 
mica is present, it is always a white mica. 

The following microscopic slides from these unaltered grits 
were described by Mr. Teall :-— 

(5695) Cnoc-na-Moine (139 N.W.—W.).—Medium-grained grey 
quartzose grit or quartzite. Large grains of quartz and turbid felspar, 
together with micro-crystalline quartz, chlorite, etc. Quartz- 
felspar-grit. 

(5696) 1 mile north-west of Inverliver (131 S.W.-W.). Fine- 
grained greenish schistose rock. Quartz, felspar, sericitic mica, 
chlorite, etc. Fine-grained schistose grit. 


Both the Ardrishaig and the Loch Awe Series have shared in the 
foldings and crumplings which have been so fully described by 
Messrs. Gunn, Clough, and myself in the south-eastern extension 
of this district in Cowal. 

The beds have been intensely folded, and the folds are often so 
closely packed that it is common for both limbs of the fold to hade 
in the same direction. In the area to which this paper refers these 
packed foldings are so numerous that no reliable estimate of the 
dip of the stratigraphical divisions as a whole can be based on such 
data. The mapping of the ground, for instance, between Loch 
Fyne and the Sound of Jura has shown that the Loch Awe Series 
is lying in a gentle trough of the Ardrishaig Series. In following 
a section from Ardrishaig to Craignish, we find the Ardrishaig 
Series near Lochgilphead being replaced by the Loch Awe Series, 
which occupy an horizon here 5 miles in width, after which the 
Ardrishaig Series comes up again. Although these Loch Awe beds 
are lying in a very gentle trough of the Ardrishaig Series, the dips 
are at a very high angle, continually increasing till, on an axis 
corresponding roughly to the prolongation of Loch Awe, they 
become vertical, and from this axis to Loch Craignish the dip 
gradually lessens till it assumes the normal angle of about 30° at 
Loch Craignish, much the same amount as at Ardrishaig, but the 
beds dip in contrary directions. The dips, however, in such a folded 
area merely indicate the hade of the limbs of the folds, which bear 
no relation to the inclination of the division as a whole. In this 
area of the Loch Awe basin it happens that, where the dips are 
nearly vertical, the beds, taken as a whole, are nearly horizontal. 
A remarkable instance of this structure is observed on the north 


476 MR. J. B. HILL ON PROGRESSIVE METAMORPHISM [Aug. 1899, 
coast of Eilean-nan-Coinean. In this section calcareous quartzose 
beds and argillaceous beds sharply alternate, and, although the 
dips are at high angles, the beds on the whole are seen to be 
nearly horizontal. It matters not whether we are dealing with 
dips of foliation-planes or dips indicating the hade of limbs of folds: 
as factors in estimating the thickness of a series or the general 
stratigraphical position of the series as a whole, they must be 
disregarded. 

Although, for the sake of convenience, I have classified these rocks 
in two divisions—namely, the Ardrishaig Series and the Loch Awe 
Serles—it is important to bear in mind that they form 
part of one great group. The Ardrishaig Series passes 
continuously up into the Loch Awe Series without a 
break. Wherever possible, the black-slate zone has been taken 
as an arbitrary divisional line between the two series. This zone 
makes its first appearance with the main limestone. It does not 
always come on sharply, but small divisional partings of the material 
often make their appearance in ribbon-like bands near the top 
of the Ardrishaig slates. In sections where the limestone is not 
represented, the accession of graphitic material is sometimes so 
gradual that it becomes a matter of great difficulty to decide where 
the Ardrishaig slates end and the Loch Awe Series begins. 


LY. T'nx Intevusive Ienzovus Rocks oF THE AREA. 


Both the Loch Awe and Ardrishaig Series are pierced by innu- 
merable sills of epidiorite, hornblende-schist, and chlorite- 
schist. They occur in such abundance that in a great part of the 
district they occupy at least half of the entire area. Like the schists 
in which they occur, these igneous intrusions vary in the amount of 
alteration that they have undergone, not only among themselves, 
but even in different parts of the same mass. Where the sediments 
have undergone least alteration we find these igneous masses in 
their most unaltered state ; as the sediments become more altered, so 
do these igneous masses. They vary in composition from basic to 
intermediate rocks. ‘Their dominant minerals are hornblende and 
felspar, with chlorite, epidote, calcite, and iron-ores as accessories. 
Biotite is rare in the unaltered rocks. 

Many of them in the field are modified diorites, others are altered 
gabbros. ‘These coarse varieties are seldom very foliated, except at 
their outer edges. A big, highly foliated mass will often contain 
zones that are not foliated at all, though there is usually a tendency 
for the crystals to arrange themselves with their long axes parallel. 
There is every gradation in these rocks from a coarse gabbro- 
structure to the finest schists. The hornblende and felspar have 
a habit of occurring as porphyritic crystals, as well as forming part 
of the groundmass. As a rule, in rocks where the felspar is 
markedly porphyritic the hornblende is not porphyritic. But this is 
not always the case: porphyritic crystals of both hornblende and 


ee ee ee 


| 


Voll 55:'| IN THE REGION OF LOCH AWE. ATT 


felspar may be scattered through the same rock, or hornblende alone 
may occur in porphyritic crystals. The porphyritic crystals, whether 
of hornblende or felspar, are sometimes so packed together as to 
form the main mass of the rock. A common structure is the 
ageregation of felspar- and hornblende-crystals in shapes correspond- 
ing roughly to those of the hornblende-prisms, forming crystalline 
ageregates. Instead of porphyritic crystals of hornblende, we see 
the outlines of hornblende-crystals, but the mineral substance itself 
that builds up the crystal is an admixture of hornblende and 
felspar. 

Sometimes hornblende is altogether absent, and its place is occupied 
by chlorite. Large masses of such rock occur in the neighbourhood 
of Loch Awe and Kilmartin. Many of them in the field can hardly 
be distinguished from sediments occurring as a green chlorite-slate. 
They contain zones, however, full of porphyritic felspar, when their 
igneous character can be readily determined. The felspars occur in 
well-formed crystals, but in many cases they are broken and jointed, 
and their angles rounded ; yet, notwithstanding the foliated and in 
many cases very fissile character of the matrix, they have often suffered 
very little crushing. Some zones are literally packed with these 
porphyritic felspars, leaving little room for the groundmass. They 
sometimes exceed 4 inch in length. Calcite is often associated with 
this type of rock, and the felspar, when it has been determined, 
has been found to be labradorite. 

There is every gradation between these chloritic and hornblendic 
rocks. Usually in chloritic rocks a certain amount of hornblende 
of the pale platy variety is found. In the same mass as that in 
which these chlorite-varieties occur, the coarsest hornblendic types 
are sometimes observed. The hornblende is always green; the very 
dark hornblende is seldom or never met with in these unaltered 
areas. 


The following slides have been selected as the most typical from 
those examined by Mr. Teall, belonging for the most part to the 
Geological Survey collection :— 

(4366) Ford, Loch Awe.—Pale greenish schistose rock of fine 
grain end somewhat earthy aspect. The main mass is a schistose 
ageregate of more or less lath-shaped felspar, chlorite, and iron- 
ore. Here and there are some large felspars which form ‘eyes’ 
in the schistose matrix. Calcite is scattered through the rock. 

(4367) Ford, Loch Awe.—A similar rock to 4366, but containing 
numerous idiomorphic felspars in a matrix which shows little or no 
schistosity. The idiomorphic felspars are labradorite. Matrix of 
more or less lath-shaped felspar, chlorite, carbonates, and iron-ores. 

(5688) Near Kilmartin.—Coarse-grained, greenish, massive rock. 
Large irregular patches of green uralitic (?) hornblende, chlorite, 
epidote, partially saussuritized felspar, and iron-ores changed to 
leucoxene, Epidiorite. 
~ (5687) Near Kilchrenan.—Dark, medium-grained, massive rock. 
Large patches of green uralitic (?) hornblende, aggregates of 


478 MR. J.B. HILL ON PROGRESSIVE METAMORPHISM [ Aug. 1899, 


brown mica, iron-ores entirely changed to leucoxene, large irregular 
patches of felspar, epidote, green aggregates of chlorite, and ven 
long broken prisms of apatite. 


These epidiorites and hornblende-schists are clearly in- 
trusive. They havea habit of occurring as sills, and it is not always 
that good evidence of their intrusive nature can be obtained. In 
the most unaltered areas, however, whenever a junction can be seen 
between these epidiorites and the argillaceous or calcareous sedi- 
ments, contact-alteration can be detected: the sediments near the 
junction are intensely indurated, and will often no longer split along 
their structural planes and joints. Argillaceous rocks are converted 
into porcellanite, and limestones are often hardened. Besides this 
induration, colour-banding has been set up in these argillaceous 
or calcareous rocks, colours due to slight differences in composition 
showing out far more prominently in the baked rock than in its 
normal condition. Near Kilchrenan, where the sediments are least 
altered, there is an example of a limestone, for 4 to 6 feet from its 
junction with an epidiorite, having been converted into an epidosite. 


Besides the enormous amount of foliated igneous rocks now 
represented by the hornblende- and chlorite-schists, intrusive 
igneous rocks of post-schistose age are numerous over 
the whole area. While the direct object of this paper would not 
be furthered by a discussion of the interesting petrological phenomena 
elucidated by a study of these various unfoliated intrusions and their 
relationships one to another, a description of the area would neces- 
sarily be incomplete that did not briefly refer to so dominant a 
feature of its geology. 

In the northern part of the district we have the great protrusion 
of Glen Fyne granite on the eastern flank, and the still larger 
granite-mass of Ben Cruachan on the west. Between these two 
masses we find smaller protrusions of granite, diorite, monzonite, 
and rocks allied to hyperite, evidently related to these larger intru- 
sions. In the north-eastern part of the area a numerous body of 
sills occur on the eastern slopes of Upper Loch Fyne and of Glen 
Fyne, and have their northern boundary very near the edge of the 
Glen Fyne granite, with which they may probably have a relation. 
They may be described generally as porphyrites, they vary in width 
from a few feet to a dozen yards, and the group has a lineal ex- 
tension of about 6 miles. 

Farther west, between Loch Fyne and the watershed between 
that loch and Loch Awe, occurs a set of intrusions of a different 
character. They run parallel with the strike of the strata, but 
they may often have a width of over a mile, and one of these sills 
extends over the entire length of the zone in which they occur, 
having been traced for more than 15 miles. They are quartz- 
porphyries of an unusual type, and are very closely related one 
to another. Besides quartz, the felspar and biotite are also porphy- 
ritic, and the rock is really a quartz-felspar-biotite-porphyry. The 
biotite commonly occurs in stumpy prisms. 


Vol. 55.] IN THE REGION OF LOCH AWE. 479 


The western part of the area possesses likewise its own type 
of sills. These belong to the porphyrite-group. While they 
are met with over the whole of the western division of this region, 
they are most abundant where they occur as intrusions in the 
volcanic series of Lorne. These volcanic rocks of andesitic type my 
colleague, Mr. R. G. Symes, has shown by paleontological evidence 
to belong to the age of the Lower Old Red Sandstone, and my 
colleague, Mr. H. Kynaston, who has mapped these porphyrites in 
Jarge numbers in the district between Loch Awe and Loch Etive, 
considers that they represent the intrusive phases of these Lower Old 
Red eruptions: he has gone fully into the question of these rocks 
in the Annual Reports by the Director-General of the Geological 
Survey for the years 1897 & 1898. Theage of the quartz-porphyries 
and porphyrites of Loch Fyne cannot be so accurately determined. 

Besides these groups of porphyrites and quartz-porphyries, 
which are fairly definite in character, there is another set 
of intrusions of extremely variable composition, but agreeing 
more or less in their mode of occurrence, which have been classed 
together in the rather unsatisfactory group of lamprophyres. 
They usually occur as sills, and inelude rocks of acid and basic 
type. In this area the bulk of them are basic, but the group also 
contains rocks of dioritic character, and varieties of porphyrites as 
well as rocks which are allied to hyperites. Rocks of this kind 
are found over the entire district to which this paper refers, but 
they are most numerous in its northern parts. The typical 
dark basic lamprophyres form a big group in Glen Shira, where 
they occur as a set of sills parallel to the porphyrite-group of 
Glen Fyne, avd occupying an horizon of very similar extent. It is 
noteworthy, too, that they come on in large numbers just where ths 
quartz-porphyry group dies out, and they appear to play the same 
part in Glen Shira that the quartz-porphyries do to the south, and 
the porphyrites to the: east. The lamprophyres of Glen Shira 
would appear to be later than the quartz-porphyries, which they 
replace, there being at least one clear instance of a lamprophyre 
intruded into a quartz-porphyry. 

The porphyrites, quartz-porphyries, and lamprophyres have been 
cut by a set of basalt- and dolerite-dykes. These are of 
two types—the east-and-west type, which is rare, and the north- 
west type, which is not only the later but is the common form of 
dyke in the area. These latter are so numerous that they 
literally occur in hundreds. While they are prevalent over the 
entire region, they are most numerous in the great central belt 
which traverses the southern half of Loch Awe and the valley 
of Kilmartin beyond. They vary in character from coarse 
dolerites to the finest-textured basalts, and in composition from 
augite-andesites or andesitic basalts to olivine-basalts. They have 
been fully described by Messrs. Gunn, Clough, and myself in the 
Survey memoir on Cowal, and by Sir A. Geikie,* who considers 
them to be related to the Tertiary volcanic rocks of Mull. 


1 «The History of Voleanic Action during the Tertiary Period in the British 
Isles, Trans. Roy. Soc. Edin. vol. xxxv (1890). 


480 MR. J. B. HILL ON PROGRESSIVE METAMORPHISM _[ Aug. 1899, 
e 
VY. Evipence or Procresstve MeramMorPuismM. 


The mapping of the district has shown that the different zones 
between Loch Fyne and Loch Awe have a steady north-easterly 
strike. Not only has the series as a whole a steady strike, but the 
different beds which are contained in them pursue a more or less 
even course in a north-easterly direction. As the beds are 
continued past the upper reaches of Loch Fyne, we have, for the 
first time for many miles, a change in the persistent north-easterly 
strike. The Ardrishaig and the Loch Awe Series are here arranged 
in a series of compound folds, by means of which the outcrops are 
curved backwards and deflected for several miles to the west of the 
general line of outcrop. By this means the beds of the Ardrishaig 
Series, hitherto occupying more or less the horizon of Loch Fyne, 
have been curved round to the westward until they not only reach 
Loch Awe, but make up the island of Inishail and small islets in its 
vicinity, at the mouth of the Pass of Brander, and extend for about 
2 miles on the west side of Loch Awe before they loop round, 
and continue a more or less easterly direction past Dalmally, 
until they reach the western flanks of Beinn Laoigh, when they 
pursue their normal north-easterly direction. The lower members 
of the Loch Awe Series, of course, follow round the fold in 
conformity with the Ardrishaig Series that hes below them. It 
is in this big loop formed by the fold that the progressive meta- 
morphism is best seen. The beds occurring in the extreme end 
of the loop on the west side of Loch Awe are comparatively 
unaltered. The same beds, continued to the north, north-east, 
and east, eventually pass within the space of a few miles into 
coarsely crystalline granulitic rocks. The rocks in their least 
altered forms can be best seen in that part of Lorne, on the west 
side of the Pass of Brander, that lies between Kilchrenan to 
the south, and Tervin on the Pass of Brander to the north. The 
beds are very much folded, with dips of folds at various angles ; 
yet the series as a whole is nearly horizontal, so that one 
particular zone of the series may occupy a large area. From 
Kilchrenan to Ben Laoigh, in an easterly direction, the change is 
gradual. Proceeding from the Kilchrenan district northward to the 
Pass of Brander, the change issudden and rapid. In this instance, 
however, we are approaching directly the great mass of the Cruachan 
granite, and much of the alteration can with certainty be assigned 
to contact-metamorphism produced by this granite. I will describe 
first the alterations produced in the Ardrishaig phyllites as they are 
traced from west to east. 

In its least altered state the Ardrishaig Series is well seen on the 
coast at New Inverawe, the southern entrance of the Pass of Brander, 
Here grey and greyish-green phyllites occur, lying nearly flat, the 
strata sometimes rolling, They are made up of thin alternations 
of phyllite and limestone, the phyllite preponderating. In places 
the phyllites are very little removed in condition from clay-slates, 
They split along cleavage-planes, and show a lustrous surface on those 


Vol. 55.] IN THE REGION OF LOCH AWE. 481 


planes, due to the development of sericitic mica. The mica, how- 
ever, does not occur in definite recognizable crystals, but yet in 
sufficient quantity to give to a fresh surface a distinct lustrous sheen. 
On the weathered surface no mica is seen at all, and the rock 
cannot be distinguished from a clay-slate. Although the rock is 
cleaved, the bedding is quite distinct and clear, slight variations in 
colour and texture making the bedding prominent even in a homo- 
geneous condition. The surfaces of the cleavage-planes are smooth, 
and usually quite free from puckerings. Besides the thin limestones, 
very fine-grained quartzites and quartz-schists are intercalated. 
These are well seen in the burn-sections immediately west of Tervin.. 
Proceeding along this strike, they are now met with in Eilean Beith 
and Fraoch Eilean. Here they are green, highly calcareous slates, 
associated with very fine-grained quartzites and hornblende-schist, 
all in precisely the same comparatively unaltered condition as at 
New Inverawe. Still following the strike, they are next seen on the 
mainland at Lag-na-Linnge on the east coast of Loch Awe, where 
they occur as greyish-green phyllites associated with thin limestones, 
and in the same unaltered condition as where first seen across the 
loch at New Inverawe. From the east side of Loch Awe they may 
now be traced continuously to the eastward without the interruption 
of large sheets of water. As they approach Dalmally some zones 
still retain their unaltered appearance, but the beds on the whole are- 
more crystalline. Instead of the uniform greyish-green tint on a fresh 
face as seen at Inverawe, the colour is less uniform, because of the 
development of scales of chlorite and the differentiation of the chlorite 
from the mica. A mile still farther east, in the burn that passes 
the Inn at Dalmally, they are no longer phyllites, but are in the 
condition of mica-schists, with mica well developed on foliation- 
planes, and the white sericitic mica and green chlorite markedly 
differentiated. Here biotite begins to appear in long blades and 
irregular blotches; the biotite is not affected by later movements.. 
Proceeding still farther eastward, the micaceous beds assume a more 
silvery appearance by the increased development of mica, The 
beds are also now intensely puckered, steady dips being no longer 
discernible. Although the zone as a whole persists in an eyen 
course, the foldings and puckeriugs within the zone are enormous ; 
the beds are also beginning to become far more indurated, and 
weather out in crags; farther west they are so soft that hollows 
are readily formed out of them. Approaching the neighbourhood 
of Ben Laoigh, they are not only intensely puckered and more. 
highly crystalline, but are considerably hardened. At Socach, 
about 8 miles east of Dalmally, these processes of deformation have. 
gone so tar that one is reminded of similar metamorphic characters 
in the anticlinal district of Cowal ; they are coarsely crystalline, big 
flakes of white mica and green mica or chlorite being interleaved. 
They contain here also a large amount of extravasated quartz, folded 
and crushed. Unaltered biotite is developed, especially in the 
calcareous portions. Small garnets may also occur in the indurated 
calc-sericite. An excellent section of this coarsely-crystalline 


@. J. G.S. No. 219. Ot 


482 MR. J.B. HILL ON PhOGRESSIVE METAMORPHISM _——[ Aug. 1899, 


calcareous sericite-schist is seen in the Eas 4 Ghaill burn near Socach. 
These micaceous beds of the Ardrishaig Series, which in the Loch 
Fyne area have a width of outcrop of about 6 miles, narrow a little 
north of Inveraray to under 4 miles. Still farther north-east, 
about 4 miles south of Dalmally, the breadth of outcrop is only 
23 miles ; here, however, the great compound fold before spoken of 
begins. By the time it has swept back to its normal position at 
Socach it is represented by a width of about 4 mile. From Socach 
the Ardrishaig beds sweep round the flank of Beinn Laoigh into 
Perthshire, and have been traced as calcareous sericite-schists into 
the heart of the Central Highlands, where they appear in such a 
metamorphosed condition that their sedimentary character has often 
been entirely destroyed, and they have been sometimes mistaken for 
igneous rocks. 

Here, then, within a distance of about 6 miles, one is able to 
follow rocks little removed from the condition of clay-slates into 
highly crystalline rocks of the normal Central Highland type. 
Further, the sections from rocks of the least altered to rocks of the 
most altered character can be continuously followed without a 
break. 


Having now dealt with the Ardrishaig division of the group, I 
will proceed to describe the changes that occur in the next division 
of the series, which I have for convenience called the Loch Awe 
Series. As previously pointed out, the Ardrishaig phyllites are 
succeeded uninterruptedly by :— 

Limestones, 


Black slates, Locu Awe SERIEs. 
Grits and quartzites. | 


In following the Loch Awe beds round the great compound fold, 
we find corresponding changes in them proportionate to the amount 
of alteration in the Ardrishaig phyllites that underlie them ; or, in 
other words, where the Ardrishaig phyllites are found in an un- 
altered condition the Loch Awe beds preserve a similar character. 
Where the Ardrishaig phyllites have been most altered and rendered 
coarsely crystalline, as at Socach, a similar change has been seen in 
the Loch Awe Series, into which they pass upward. 

Limestone.—The first member of the series to be dealt with is the 
limestone. Beginning, as before, in the least altered district on the 
south side of the Pass of Brander, we find the Ardrishaig phyllites 
passing up into limestone associated with more or less black slate. 
These beds are well seen in the country extending from Tervin to 
Lochan-na-Cuaig. As they approach the Pass of Brander, however, 
they become curiously altered. Epidote at first appears sufficiently 
in the limestone to colour the rock in places ; but on approaching the 
Pass of Brander, between Tervin and Lochan-na-Cuaig, an abnormal 
amount of epidote is developed, and the rock assumes a curious 
banded appearance, with colours varying from purple to yellow and 
green, yellowand green bands being the commonest. It must be re- 
collected that the limestone is not pure ; itis often associated with a 


Vol. 55. IN THE REGION OF LOCH AWE. 483 


large amount of argillaceous material, either of the green calcareous 
variety belonging to the Ardrishaig Series or the dark variety of 
phyllite belonging to the Loch Awe division. At one place near 
Lochan-na-Cuaig much extravasated quartz was seen, some of which 
had shared in the folding and some was of later date. The purplish 
bands represent the dark partings of phyllite. These beds are con- 
tinued on the north side of the Pass of Brander, where they are 
well seen at the Falls of Cruachan. On the north side of the Pass 
they are, however, if anything, more altered, the dark phyllitic 
partings being here represented by coarse mica. This epidotic banded 
limestone is intensely hard, and stands out in the section like a 
quartzite. The limestone has been converted into cale-hornfels, 
and is very prevalent in this condition along the Pass of Brander. 
When in this state it will only effervesce feebly with hydrochloric 
acid, and in many cases not at all. 

A specimen from Tervin showed under the microscope ‘ dirty 
ageregates of epidote, carbonates, etc.’ (5704). Another specimen, 
in which the alternations of phyllite were well seen, is thus described 
by Mr. Teall :— 

(5705) Pass of Brander.—Fine-grained banded rock. Alterna- 
tions of black and greenish-grey bands. The dark bands are mainly 
composed of mica (phyllite); the lighter bands consist of quartz, 
epidote, carbonates, ete. 

(5706) North side of the Pass of Brander.—Pale grey compact 
rock. Confused aggregate of granulitic quartz and felspar, zoisite, 
and perhaps epidote. 

In another specimen, from the Falls of Cruachan, a white double- 
refracting garnet was detected by Mr. Teall. 

A rock very similar in character to these occurs in Gleann 
Strae, about 2 mile north of Dhuletter. It is here a greenish rock 
containing crystals of epidote, with intercalations of black phyllite 
A specimen was sliced, and is described as follows :—(5708) Dark 
greenish compact rock. Quartz, felspar, carbonates, ete. 

Exposures of the limestone are seen here and there in its proper 
position at the top of the Ardrishaig Series between Dalmally and 
Socach. At Socach, where the Ardrishaig phyllites have become 
coarsely crystalline, a good exposure of limestone is seen capping 
the hill of Barr Dubh. A good deal of micaceous schist is mixed in 
with it, and biotite and actinolite are largely developed. 

The following sections, described by Mr. Teall, are from altered 
limestones in the highly altered area to the north of the Strath of 
Orchy :— 

(5701) 14 mile north of Inverlochy.—A dark medium-grained 
schistose rock. Carbonates (calcite), chlorite, quartz, pale brown 
mica, garnets, and iron-ores. 

(5698) 4 mile south of Beinn Donachain.—A medium-grained, 
dark-grey, schistose, calcareous rock. Micaceous lustre strongly 
marked on the uneven planes of schistosity. A confused aggregate 
of pale-brown biotite, white mica, chlorite, calcite, felspar, and 
epidote. Calc-biotite-schist. 

Ze 


484 MR. J. B. HILL ON PROGRESSIVE METAMORPHISM  [ Aug. 1899, 


(5699) Near Creag Loisgte, Dalmally.—Greenish-grey schistose 
rock. Felspar, quartz, carbonates, a nearly colourless micaceous 
mineral, chlorite, and iron-ores. 

(5700) Na Cailleachan.—A moderately coarse-grained schist, 
containing much pale brown mica. Quartz, felspar, carbonates, pale 
brown mica, and the nearly-colourless (pale greenish) micaceous 
mineral mentioned in describing the last specimen. 

In this highly-altered area, between Gleann Strae and Glen Orchy, 
the limestones are metamorphosed almost beyond recognition. 
There is one instance of a limestone, 4 mile south of Beinn Dona- 
chain, crammed with prisms of actinolite, many of them quite an 
inch in length. 


Black Slate.—tThe black slates which occur in association with. 
the limestone do not show in the field the same marked alteration 
in character as that which has been observed in the Ardrishaig 
phyllites and the limestone. Corresponding alterations have, never-- 
theless, been induced in them. On the north side of the Pass of 
Brander, where they occur in association with the limestones and 
quartz-schists, they are much more micaceous than on the south side 
of the Pass. A similar change can be distinguished in tracing them 
from Dalmally to Socach. Near Socach they are also more massive 
than at Dalmally, as well as darker in hue. In the highly-altered 
area near Socach and Inverlochy they contain zones of big garnets 
and actinolites. ‘The garnets are sometimes as big as marbles, and 
are earlier than the latest foliation which has travelled round them. 
The beds have also been folded since the introduction of the garnets. 


Grits and Quartzites.—As stated earlier, the black slates pass- 
up into grits and quartzites, with which they are distinctly asso- 
ciated. In the neighbourhood of Socach is seen the usual succession 
of the Ardrishaig phyllites giving place to limestones, black slates, and 
finally grits. The grits, however, have suffered the same extreme 
metamorphism as that which has affected the Ardrishaig phyllites, 
limestones, and black slates. They become quite granulitized and, 
by recrystallization, pass, in their extreme phase of metamorphism, 
into gneissose rocks. Among the quartzose rocks both black and 
white mica have been abundantly developed. But, notwithstanding 
the amount of granulitization, the coarser grit-bands can still be 
detected ; although the larger pebbles are flattened, pulled out, and 
crushed, the alternations in bedding of coarser and finer bands can 
be seen, and the coarser conglomeratic zones occurring in the less. 
altered beds to the westward are here represented. The black slate- 
partings are also still recognized, but no longer in the condition of 
a slate, having been altered into a hard, dark, micaceous rock. 

The pockets of phyllites within the grit, so characteristic of the 
unaltered beds farther west, are still seen in these highly-altered 
quartzose beds. Like the slate-partings, however, they have 
been converted into dull lead-coloured, crystalline, micaceous 
material. The rocks no longer, in weathering, show the distinctive 


Vol. 55. ] IN THE REGION OF LOCH AWE. 485 


characters of hard and soft alternations. The micaceous partings 
and the quartzite-bands have, as it were, become welded into a solid 
homogeneous mass. The dark micaceous alternations, when the 
rock is in this condition, impart a banded structure and a bluish 
coloration to the rock. The enormous quantity of secondary biotite 
which is scattered through both the quartzose and micaceous zones 
still further darkens them. These grits and quartzites have 
passed into rocks which are gneissose in character; the more 
Siliceous, however, remain as quartzites and quartzite-schist. 
These granulitic and gneissose rocks occupy the area to the north 
of the Strath of Orchy till they are cut off to the westward by the 
Cruachan granite. From this Strath of Orchy area they stretch away 
north-eastward into the Central Highlands as quartzites, gneissose 
flagstones, biotite-gneisses, etc., and in the Central Highland area, 
so far as is known at present, they retain this highly crystalline 
character without reverting to the comparatively unaltered condition 
in which they are found in the Loch Awe basin. 

Biotite, garnets, actinolite, small tourmalines, epidote, and red 
felspar are common as secondary minerals in this highly-altered 
area. The biotite has been one of the latest minerals to crystal- 
lize, and has been generally unmoved; the same may be said 
for the tourmalines and red felspars, though these latter may be 
sometimes broken. The garnets and actinolites attain considerable 
dimensions; garnets occur up to 4 inch in size, and actinolites 
are in blade-like forms sometimes 1 inch long. The garnets and 
actinolites are commonest in the micaceous beds. The former, 
too, have a habit of occurring thickly in certain zones; for 
Instance, one bed was observed in the neighbourhood of Glen 
Orchy 6 feet wide, literally studded with garnets 4 inch in size 
or even larger. In this case the foliation was clearly seen to curve 
round the garnets, which, besides being crushed, were often cleaved 
parallel to the foliation-planes of the rock. In many cases, 
however, these garnets show no sign of movement, but preserve 
their external crystalline outline. Small black tourmalines about 
2 inch long are also seen quite unmoved. 

Red pegmatites are seen in the area lying between Glen Orchy 
and the Cruachan granite. They occur as red felspathic material, 
filling up joint-planes, and are common in quartz-veins. These 
felspathic veins are always unmoved ; they belong to the same set of 
phenomena as the introduction of the secondary red felspars among 
the quartzose rocks of this area. This felspathization is clearly 
connected with the presence of the Cruachan granite. The 
quartzose schists on the western side of Gleann Strae into which 
the granite has intruded display this condition in a marked 
degree. The felspathization has proceeded so far that the whole 
hillside presents a pinkish hue, in place of the normal pale- 
grey colour of these quartzite features. Near the granite-margin, 
isolated crystals of red felspar appear sometimes up to 1 inch 
in length, while felspars 4 inch long are quite common. With 
these larger crystals smaller felspar-grains are associated, and as 


486 MR. J.B. HILL ON PROGRESSIVE METAMORPHISM _[ Aug. 1899, 


one recedes from the granite the large crystals are no longer 
observed. The felspar occurs also in veins and strings along joint- 
planes, or even along foliation-planes, and in these latter the felspar 
increases in amount as a joint-plane is approached. Usually, how- 
ever, when at some distance from the granite the felspar occurs as 
small isolated red grains irregularly scattered through the rock. 
While there can be no doubt that in the neighbourhood of the granite- 
margins the felspathic material has been introduced into the schist, 
it cannot be demonstrated that this is the case when we are dealing 
with the isolated felspathic grains at some distance from it, as the 
schists themselves were originally rich enough in felspar to have 
supplied the necessary material. 

It may be added that these secondary felspars are similar to 
those contained in the granites, some, for example, are orthoclase,. 
others are alkaline felspar enclosing oligoclase, and there are also 
traces of microperthite. All these characters have been detected in 
the felspars of the granite. 


Epidiorites, etc.—The epidiorites and hornblende-schists have 
undergone great alteration in this highly-metamorphosed area: 
between Gleann Strae and GlenOrchy. They have been considerably 
granulitized and partially recrystallized. The hornblende is usually 
darker, and black actinolite has often been developed. In this: 
particular district of Gleann Strae and Glen Orchy the chlorite that 
occurs in the unaltered area to the south and south-west has been 
converted into hornblende. The porphyritic crystals of felspaz 
which have been described as occurring with clear crystalline out- 
lines in the chlorite-schists and chloritic hornblende-schists to the 
west have been considerably granulitized, and are here represented 
only by irregular blotches; their character, however, can clearly 
be recognized. Biotite and garnets are common as accessory 
minerals. A specimen was selected from a hornblende-schist in 
the highly-metamorposed area and reported on by Mr. Teall as 
follows :—(5689) Dark greenish crystalline schist. Hornblende, 
biotite, quartz, and felspar; structure granulitic. Coarser bands 
or veins of quartz and idiomorphic felspar occur in the granulitic 
schist. Hornblende-biotite-schist. 

In the neighbourhood of Socach, where the epidiorites occur,. 
crystals of secondary white mica have been observed in them.. 
Epidote is also a common accessory mineral in this neighbourhood. 

A remarkable type of epidiorite that occurs about 2 miles south- 
west of Dalmally may be conveniently described here. It occupies 
an area considerably over a square mile in extent, just where a rapid 
change of metamorphism is first beginning to be observed. While 
the peculiarities of the rock cannot be altogether claimed as a 
product of metamorphism, its occurrence in the critical zone of 
rapidly-changing conditions and within a mile of the Cruachan granite 
is suggestive. The eastern part of this mass is a coarse hornblende- 
felspar rock, not very schistose, in which the hornblendes are often 
of considerable size; but the rock frequently becomes fine-grained.. 


ro ——— 


Wol. 55.] IN THE REGION OF LOCH AWE. 487 


Farther westward it often passes into a rock of quite a different 
character, pale patches consisting of fine-grained felspars and blue 
quartz, with hornblende and chlorite occurring in foliation-planes. 
With these occur rocks of more normal epidioritic character, 
with plenty of hornblende and porphyritic crystals of felspar, 
becoming occasionally fine-grained and containing epidete. Even 
in the more basic varieties the rock has the same peculiar 
pale patches (composed of aggregates of felspar and quartz). The 
felspar and quartz of these aggregates are often so intergrown as 
to form micropegmatite. Towards the westernmost part of the 
mass the rock assumes quite a banded or gneissose character. It 
is very massive, highly foliated, largely made up of felspar-aggregates 
usually pinkish, small grains of quartz, dull fine-grained chlorite in 
foliation-planes, some dark blotches of biotite in aggregates, and 
small pegmatite-veins. In parts the rock is as acid as granite. 
Big blotches of biotite seem to have replaced actinolite. Quartz 
is very abundant, and quartz-veins in the rock are largely blue. 

The following are descriptions of two sections taken from this 
rock-mass, the first of which was obtained from the rock with 
biotite; the second refers to that part of the mass containing horn- 
blende :— 

(5684) Medium-grained crystalline rock with no marked foliation. 
The white patches are aggregates of felspar and quartz, often inter- 
grown so as to form micropegmatite. The dark parts are aggregates 
of biotite, epidote, and iron-ores. . 

(5685) Medium-grained crystalline rock, similar in structure to 
that just described, but with the darker parts greenish. The light- 
coloured parts of the rock are formed of idiomorphic and more or 
less epidotized felspar with interstitial quartz and micropegmatite. 
The darker portions contain hornblende, chlorite, and iron-ores zoned 
with sphene. 


Boulder-bed.—In comparing the unaltered rocks of Loch Awe 
with the crystalline schists of the Central Highlands into which they 
pass, I have been describing beds which are more or less continuous 
along their line of strike. JL will now describe a deposit known as 
the Boulder-bed which occurs occasionally in the Highland series 
along an horizon extending from Aberdeenshire to Islay. Although 
the deposit is not continuous, it is seen so often in the Central High- 
lands among the highly-altered schists that its absence from the 
comparatively unaltered area of the west might be construed as 
evidence against the identity of the Central Highland rocks with 
those of Loch Awe. On the other hand, its occurrence in both areas 
on similar geological horizons may be accepted as a valuable link 
in the chain of evidence which has been submitted that these rocks, 
notwithstanding the variable condition in their metamorphism, are 
one and the same. 

I have stated earlier that the Ardrishaig phyllites are succeeded 
by a series composed of black schists, limestones, and grits, and that 
this succession holds good across the Central Highlands, whether 


488 MR. J. B, HILL ON PROGRESSIVE METAMORPHISM  [ Aug. 1899, 


we are dealing with the unaltered sediments of Loch Awe or their 
extension into crystalline schists to the eastward. The Boulder- 
bed, although not a continuous deposit, makes its appearance here 
and there across the Highlands from near Braemar on the east to 
Islay on the west. Along this belt of country it has a fairly definite 
stratigraphical position. It always occurs in the series referred 
to in the present paper as the Loch Awe Series, but it may occur in 
different members of this division. Its most general position is in 
the quartzite member of the Loch Awe Series, but in Argyllshire it 
has also been met with in the limestones and black-schist members 
of that series. My colleague, Mr. G. Barrow, informs me that in 
the Schiehallion area of Perthshire the Boulder-bed is made up 
almost entirely of large boulders of granite. In the area far to the 
south of Braemar the pebbles are smaller and still mostly igneous, 
while 4 miles south of Braemar the bulk of the pebbles are sedi- 
mentary. In the Loch Awe area the Boulder-bed has been observed 
in many localities within the Loch Awe Series and in every division 
of that series. The area lying between Glen Aray and Loch Awe 
in a belt passing Cruach Mhor contains numerous exposures 
of it. Along this horizon the matrix in which the boulders are 
embedded varies in different localities, and may consist of every 
member of the Loch Awe Series from grits, quartzites, dark schists, 
to the typical Loch Awe Limestone. A few of the localities are 
recorded below :— 

1 mile east of Cruach Mhor, boulders of quartzite 6 inches 
and more in length, in a dark schistose matrix. 

2 miles north-west of Cruach Mhor, quartzite-pebbles 
up to 2 inches in length, in a matrix of limestone. 

24 miles west of Cruach Mhor, boulders of grit 1 foot 
long, in a dark quartzose-argillaceous matrix. 

34 miles south-west of Cruach Mhor, boulders and 
pebbles of blue compact limestone and pebbles of blue slate, in a 
matrix of crystalline limestone. 

5 miles south-west of Cruach Mhor, boulders of com- 
pact limestone up to 1 foot in length and small quartzite-pebbles, 
in a matrix of typical Loch Awe Limestone. 

In the same district there are various localities where boulders of 
grit and quartzite occur, in a matrix of a composition similar to that 
of the boulder. 

On the west side of Loch Awe examples of the Boulder-bed 
are equally common. Still farther west, in Islay, my colleague, 
Mr. Wilkinson, has described a similar Boulder-bed where, as noted 
by Mr. Barrow in various districts of Perthshire, some of the 
boulders are of foreign material. 

The occurrence of foreign boulders, and of boulders of material 
different from the matrix, makes it quite clear that we are dealing 
with a regular sedimentary deposit, and that it does not owe its 
origin to movements such as have given rise to crush-conglomerates. 
And the position of this Boulder-bed among sediments of similar 
nature across so large a portion of the Highlands may be regarded 


Vol. 55.] IN THE REGION OF LOCH AWE. 489 
as confirmatory evidence in support of the contention that the 
deposits in which they occur are contemporaneous over the whole 
region. 


Tt has been shown that highly crystalline schists of the Central 
Highlands have been traced along their strike into beds of various 
degrees of metamorphism, which at last is so feeble in character 
that the schistose structure becomes ever less apparent, in parts 
dying out altogether. In the division known as the Ardrishaig 
Series the nature of the ground has been such that I have been 
able to join up the beds, step by step, without a break,’ along 
the strike, from the condition of highly crystalline schists to beds 
hardly more altered than the Silurian rocks of the South of 
Scotland. The evidence of this progressive metamorphism in the 
Ardrishaig Series is so conclusive that the object of this paper would 
have been attained without describing similar phenomena in the 
Loch Awe Series, which normally succeeds it. But it has been 
also shown that on similar horizons the crystallization of the Loch 
Awe Series conforms to that of the Ardrishaig Series, which lies 
next to it. Whenever the degree of metamorphism begins to 
vary in one series, a similar change is observed in the adjoining 
series. Owing to the nature of the ground and the presence of the 
great sheet of water of Loch Awe, the uninterrupted line of in- 
creasing metamorphism along the strike of this series cannot be 
continuously traced, except in the neighbourhood of the Cruachan 
granite, where the presence of this mass is responsible for much of 
the alteration and hornfelsing that come on so suddenly in the Pass 
of Brander. But although this granite has effected great contact- 
metamorphism where its southern margin abuts against these Loch 
Awe sediments, yet where they are traced in a north-easterly direction 
an their passage across the Central Highlands they do not revert to 
their former unaltered condition, even when followed far away from 
the granite. Their tendency, on the other hand, is rather to increase 
still further in crystallization. It is, therefore, evident that this 
regional metamorphism of increasing intensity would have been 
equally apparent without the presence of the Cruachan granite. 
That granite has nevertheless been a factor in determining the 
suddenness of the metamorphism, where it has invaded rocks so 
little altered that they have readily lent themselves to the processes 
of contact-metamorphism which rocks in a more advanced state of 
erystallization have been able to resist. 


In this paper I have been dealing with the progressive meta- 
morphism of beds along their strike, but in the same area we have 
ample evidence of an increasing metamorphism of the same beds when 
followed across the strike. A traverse from Loch Melfort to Loch 
Fyne crosses the strike of the beds that I have been describing in the 
Loch Awe basin. The Loch Awe beds are in this district lying in 
a gentle trough of the Ardrishaig Series, which flank them on either 
side—the Ardrishaig phyllites occurring on the shores of Loch 


490 MR. J.B, HILL ON PROGRESSIVE METAMORPHISM [Aug. 1899, 


Melfort, and making their appearance again on the coast of Loch 
Fyne. The Ardrishaig beds at Loch Melfort and the Loch Awe beds 
are in their least altered condition. As we approach Loch Fyne, 
however, towards the south-east a very different type of meta- 
morphism prevails, and the Ardrishaig beds where they occur on 
Loch Fyne are true crystalline schists, in vivid contrast with their 
unaltered character to the north-west at Loch Melfort. So that 
here, although the metamorphism is Increasing across the strike, we 
see the same series of rocks coming up again in another area in two 
very different conditions of metamorphism. 

In the neighbourhood of Loch Fyne it can also be shown that 
the Ardrishaig Series presents a gradually increasing type of 
metamorphism in a north-easterly direction from Ardrishaig ; 
this increasing metamorphism, though gradual, becomes much 
more rapid as we reach the flanks of Beinn Buidhe, 6 miles 
north-east of Inveraray, where it is accompanied by intense folding 
as well as induration, the dips, which hitherto have been steady 
to the north-west, being in parts of Beinn Buidhe so confusing 
that in some localities even a general dip cannot be ascertained. 
In this case it may be noted that we are approaching the area 
of the Glen Fyne granite, bosses of granite, diorite, and monzo- 
nite being of frequent occurrence in this highly indurated and. 
altered area. Some hornfels occurs on Beinn Buidhe very similar 
to the hornfels on the flanks of Ben Cruachan, and we may assume 
that the hornfels, at any rate, has been produced by the igneous 
masses which are connected with the Glen Fyne granite. In this 
case we are dealing with progressive metamorphism along the strike, 
in which the beds where least altered are in the condition of crystal- 
line schists. Phenomena of a similar nature have been described by 
Messrs. Gunn, Clough, and myself in the ‘ Geology of Cowal,’ where 
it has been pointed out by us that the garnetiferous mica-schists, 
which succeed the Ardrishaig Series to the south-east, gradually 
increase in metamorphism along the strike in a north-easterly 
direction; but here, also, we are dealing not with comparatively 
unaltered beds, but with rocks which are already in the nature of 
schists becoming more crystalline. 

Progressive metamorphism crossing the strike of beds has been 
observed in other portions of the Highlands. My colleague, 


1 [Since this paper was read I have revisited the district, and have detected 
typical hornfelsing in the monzonite-aureoles of Beinn Buidhe. It is inter- 
esting also to record that my colleague, Mr. R. G. Symes, has recently mapped 
in the neighbourhood of Kilmelfort some small granite-masses similar to those 
on Beinn Buidhe, and producing similar hornfelsing. The occurrence of this 
hornfelsing, in the midst of the unaltered Loch Awe beds and many miles distant 
from true crystalline schists, greatly strengthens the view advanced in the present 
paper, that the granites of Ben Cruachan and Beinn Buidhe have effected con~ 
siderable contact-metamorphism apart from the regional type which surrounds 
them. It may be noted that the hornfelsing at Kilmelfort has not been 
observed in the shales of Lower Old Red Sandstone age, but only in the older 
ay the Loch Awe Series into which the granites have protruded.—July 12th, 
1899. 


Vol. 55. | IN THE REGION OF LOCH AWE. 491 


Mr. G. Barrow, has mapped in the Central Highlands rocks starting 
from the condition of phyllites, through successive aureoles of fine 
schist, staurolite-schist, and kyanite-schist ; in this case, however, 
the zones of increasing metamorphism do not correspond with the 
strike of the beds, but cross it obliquely. 


VI. ConcLusions. 


The object of this paper has been to bring forward evidence that 
a great series of comparatively unaltered rocks spread over a wide 
area passes gradually into crystalline schists, and this fact is in 
itself so important that it has not been considered necessary to 
widen the scope of the paper by a more or less futile endeavour to 
interpret the causes which have led to these results. ‘To do so 
would involve the advancing of theories which in the present state 
of our knowledge could only be considered as matters of specula- 
tion. A few words on the subject, however, may not be out of 
place. We are dealing in the main with a type of metamorphism 
which extends over large areas and, so far as we are aware, 
removed from the neighbourhood of plutonic masses upon which it 
might otherwise have been possible to look as the metamorphic 
agency. When, however, we do approach the neighbourhood of large 
plutonic masses, such as the Cruachan and Glen Fyne granites, we find. 
ourselves confronted with a type of metamorphism more intense 
than that observed to the south-west of these granites ; but we see 
that this metamorphism does not again diminish as we recede from 
the granite-areas in a north-easterly direction. We do, however, find 
in the neighbourhood of these plutonicrocks a type of metamorphism 
which had evidently been produced by them ; but we are unable to 
say definitely where the contact-type of metamorphism ends, and 
the regional type begins. _When on the ground, I had reason to 
suspect that, in connexion with the intense progressive meta- 
morphism that occurs in the area lying between the granite-masses 
of Glen Fyne and Ben Cruachan, the intense regional type of 
metamorphism was linked with the same phenomena as those that 
afterwards resulted in the irruption of the granite-masses. But our 
knowledge of the agencies of metamorphism must be considerably 
enlarged before such speculations can Jay claim to any value. 

I have had no opportunity of revisiting the northern portion 
of the ground since 1893, when the materials’ for this paper were 
collected ; but my work on the upper part of Loch Awe, in so far 
as it relates to the contact-metamorphism of the Cruachan granite, 
has been considerably extended by Mr. Kynaston, who has dealt with 
these phenomena at length in the Annual Reports by the Director- 
General of the Geological Survey for 1897 & 1898. On reference 
to these reports it will be noticed that, in addition to the large 
amount of interesting material which he has collected bearing on these 
contact-phenomena, some microscopic slides from the hornfels-rocks 
were found by Mr. Teall to contain the minerals cordierite and 


A492 MR. J.B. HILL ON PROGRESSIVE METAMORPHISM [ Aug. 1899, 


corundum. Allusion has been made to this fact here, as the well- 
known contact-minerals cordierite and sillimanite were found by 
Mr. Teall in rocks obtained from the aureole of contact-alteration 
of the Glen Fyne granite, described in the Geological Survey memoir 
on Cowal. 

Age.—When we attempt to assign a geological age to the members 
of the Dalradian Series herein described, we are confronted with the 
difficulty that these beds have up till now failed to yield any organic 
remains that can help us in their determination. In the absence of 
such assistance we can only ascertain their stratigraphical position 
in reference to fossiliferous strata which occur among them. — 
What we do know is that they existed as crystalline schists before 
the epoch of the Old Red Sandstone, for pebbles of the schists are 
found in the conglomerates of Lower Old Red age. It will be well, 
however, to bear in mind the existence of important masses of pre- 
Cambrian sediments, now well known in Scotland as Torridonian, 
in Britanny as Brioverian, and in America as Algonkian and 
Huronian; and it is probable that these sediments may also 
eventually prove to be of pre-Cambrian age; but in the present 
state of uncertainty they have conveniently been referred to as 
Dalradian. 


Discussion. 


Sir A. Gerxie said that he had gone over the ground described in 
this paper with the Author, and had satisfied himself that the main 
fact upon which the latter insisted was undoubtedly true—that 
around Loch Awe the strata had escaped metamorphism into the 
schists that formed most of the Highlands. These strata are so little 
altered that they might be mistaken for Silurian sediments, and he 
did not despair of their yet proving fossiliferous. But they become 
progressively more highly metamorphosed as they are followed 
towards the north-east, until they pass into the ordinary Dalradian 
type of schists. Many points of extreme interest in regard to the 
general question of metamorphism and to the structure and origin 
of the Highland schists arose out of the facts dealt with by the 
Author, who had been engaged for several years in the investi- 
gation of the Loch Awe region, and had mapped it with much 
skill. It was an important step in the investigation of High- 
land geology to discriminate, so clearly as he had done, several 
distinct stratigraphical groups, to demonstrate their sedimentary 
origin, and to show their gradual lateral passage into true schists, 
apart altogether from the effects of any visible mass of intrusive 
rock. The Author had recently been transferred to Cornwall, 
where his training in the Argyllshire region would prove of great 
service in unravelling the complicated stratigraphy of that part 
of the United Kingdom. 

Mr. G. Barrow observed that the area here described is of special 
importance, as the rock-groups to which reference is made have been 
traced continuously, along the line of strike, right across Scotland. 
it has been remarked that, as these rocks enter the area permeated 


Vol. 55. | IN THE REGION OF LOCH AWE. 493 


by the older granite, they pass over to coarse gneisses. In par- 
ticular, the sills of epidiorite are altered to coarse hornblendic 
gneisses in no way differing from those seen at Cape Wrath. 
He had gone over part of the area with the Author, and they were 
both satisfied that the increase of metamorphism indicated by the 
largest arrow on the map shown at the meeting could not be 
connected with the mass of newer granite seen at the head of 
Loch Fyne. 

The Rev. J. F. Braxe drew attention to the statements made by 
the previous speakers. He understood them to say that rocks of 
Ordovician aspect, with limestones in which fossils might be looked 
for, passed by insensible gradations into typical Highland gneisses, 
including in the term the gneisses of Cape Wrath. Not knowing 
the particular district described in the paper, and the above state- 
ments being as yet no more than statements, he was not in a 
position to discuss them ; but they involved so much that he felt it 
desirable to call special attention to their significance. 


AQ4 DR. A. W. ROWE ON THE GENUS MICRASTER. [ Aug. 1899; 


32. An Anaxysis of the Genus Mrcrasrer, as determined by rigid 
zonal collecting from the Zone of RuyncewonELtLa CUVIERI 
to that of MrcrastER cor-ane@uinum. By Dr. A. W. Rows, 
F.G.S. (Read March 8th, 1899.) 


[Puares XXXV-XXXIX.] 


CoNnTENTS. 


I 'General‘Considerations):....<...--s12--eeseectesesvene tc seetae naene 494 
II. A Review of the Evolution of the Special Features of the 
Test in all Forms and at each Horizon, with a Tabular 
SS UIRETIIN AIRY’ {itor Saltcinate Gora nd jae Gea peat olen Seek on ere 499 
III. Method of Measurement of the Test, with a Synoptical 
Contrast between the Features of High-zonal and Low- 
gonial! Wormash’ $0, 40. 02a2 ace escke atch ud otis Sonetacreione en aaa 514 
LV. Division of Micraster into) Groups)... 0s.-+--cnaseveone esses 517 
(1) Group of M. cor-bovis. 
(2) Group of M. Lesket. 
(3) Passage-form from WM. Leskei to M. precursor. 
(4) Group of M. precursor. 
(5) Sub-group of M. cor-testudinarium. 
(6) Group of M. cor-anguinum auctorum. 
(7) Sub-group of M. cor-anguinum var. latior. 


Vie Coie ins Onsen decree rene aoe ete cee ec a A cee 540 


I. GENERAL ConsIDERATIONS. 


Tue Micrasters dealt with in this paper were collected from the 
sections exposed at Gravesend, the Thanet Coast, Dover, Beachy 
Head, the Dorset Coast, and Beer Head, in the zones indicated 
above. 

Two thousand examples have been measured and analysed, and 
no specimen has been included in the summary unless its zonal 
origin is accurately determined. Six hundred photomicrographic 
negatives of the special features of the test have been made, in 
order that mere conjecture may play no part in the enquiry, and 
that these important aids to specific and zonal determination may. 
be placed on a permanent and scientific footing. The field-work 
has been extended over as wide an area as possible, so that con- 
clusions should not be vitiated by being drawn from any one isolated 
district. 

In this paper, the term ‘ low-zonal’ will apply to the zones of 
Rhynchonella Cuveri, Terebratulina gracilis, Holaster planus, 
Micraster cor-testudinarvum, and the lower third of the zone of 
M. cor-anguinum (80 feet); and the term ‘high-zonal’ will refer 
to the remainder of the zone of M. cor-anguinum, and to the zones 
above it.’ 

1 T hope at some future time to publish a detailed analysis of the English 


high-zonal series, together with a notice of the sub-genus Hpézaster, and of all 
the gibbous forms. 


Mali sel DR. A. W. ROWE ON THE GENUS MICRASTER. 495 


Though all the accessible literature on the subject has been studied, 
the conclusions here set forth have not been influenced by previous 
publications, for rigid zonal collecting has been the paramount object, 
and the facts brought out by analysis have been allowed to speak 
for themselves. The scope of the present paper will not admit of 
the discussion of questions of nomenclature, which must be left to 
systematists ; but in order to avoid confusion, a reference will be 
given, when discussing species, to clear and accessible plates ; and 
where these are insufficient, illustrations will be found in the plates 
which accompany this text. 


The genus Micraster is of such high paleontological interest, of 
such value as a zonal guide, and its literature is so abundant and 
Jong established, that it is a matter of no small wonder that any 
uncertainty should exist concerning the claim of several marked and 
familiar forms to a specific distinction. 

Few fossils are more common or characteristic in the Chalk of 
England or the Continent than Mocraster, and yet, though MM. cor- 
anguimum, Leske, was described in 1778, M. cor-testudinarium, 
Gldf., in 1826, M. Lesket, Desm., in 1837 (the M. breviporus, Ag., 
1840, of English writers), and M. cor-bovis, Forbes, in 1850, we 
still seem to have no authoritative information to guide us in deciding 
whether these more or less markedly differentiated forms are mere 
paleontological curiosities, or whether they are culminating points 
in a scheme of progressive evolution—for, after all, even a marked 
variety has no claim to special distinction, unless it is fairly abun- 
dant, and possesses features which stamp it as characteristic of a 
definite horizon, and place it apart from its fellows. 

On making enquiry of well-known English paleontologists and 
field-workers, the writer was struck with the utter lack of 
unanimity in their opinions—some looking upon these marked 
forms as mere meaningless varieties, and others regarding them as 
definite species with a distinct zonal importance. It is rather 
anomalous that the other common Chalk urchin, Echinocorys vulgaris, 
should, by common consent, have its various and by no means 
valueless forms reduced to the level of varieties, while Wicraster 
should have its species multiplied to an unnecessary extent. Of 
the making of species there is no end; and this, in the case of 
Micraster, seems to have been especially prevalent on the Continent. 
On this head, so far back as 1850, d’Orbigny plaintively remarks 
that there are no less than sixteen species recorded, and he then 
proposes to reduce them to six. When a species, such as M. tropi- 
dotus, Ag., is founded on a single example, and that badly damaged, 
it is reasonable to ask whether it is justifiable to coin new species, 
in the case of genera which are very common and prone to remark- 
able variation at each separate horizon, save on the evidence of 
hundreds of zonally-collected examples. 

If we could start de novo, and work out the whole series from an 
evolutional point of view, giving appropriate specific names in the 
rare instances where they are needed, and marking salient mutations, 


496 DR, A. W. ROWE ON THE GENUS MICRASTER.  [ Aug. 1899, 


when they are useful as zonal guides, by varietal titles, we could 
then readily build up a scheme, which might have some zoological 
value, wherein specific and varietal names would be descriptive 
both of shape and horizon, thus enabling us to abolish such bar- 
barisms as cor-anguinum and cor-testudinartum. But the law of 
priority is unyielding, and we must accept, with the best grace 
that we may, such anomalies as the raising of the high-zonal 
Micraster cor-anguinum and the low-zonal M. cor-testudinariwm to 
the level of specific types, while their low-zonal ancestor, M/. precur- 
sor (p. 530),* which is equally important and abundant, is obscured 


by a cloud of specific names. 
The grievance is very real, for it is hard to have to tack on 


a varietal name to such a polysyllabic enormity as Micraster cor- 
anguinum, and yet that is just what has to be done, in order that 
we may mark an essential horizonal type. 


1 [As there is a probability of this name being adopted in the future as 
specific, it may be well to point out that. though the extreme forms graduate 
into M. Leskez, on the one hand, and into M. cor-testudinariwm on the other,. 
yet the intermediate series is as distinct as in many accepted species, the 
extremes of which are well known to graduate into other forms, but are never- 
theless accepted as valid species. 

Although, primarily, I have designed M. precursor in the broad sense asa 
group-name, it is also used in the restricted sense, when dealing with the form as- 
it occurs in the various zones. I especially state that, even in its restricted 
sense, it cannot rightly be called a species, as it is merely the same 
form, or series of contour-forms, impressed with certain special features of the 
test, which are peculiar to each individual zone, and therefore varying in detail 
from zone to zone. A group-name which embraces so Protean a series as: 
this can hardly be called, from a zoological standpoint, a true species ; and yet,. 
by usage and for the needs of classification, it is probable that it will be used in 
a specific sense, however much I may demur against such a course, 

M. precursor is only the dominant form of the narrow low-zonal type, just as 
M. cor-anguinum is the dominant form of the narrow high-zonaltype. Neither | 
of them has any valid claim to a true specific title, save that of convenience. 
If it be right to preserve M. cor-anguinum as a species, it is equally right to use 
M. precursor in the same sense. ‘These particular forms must have a name, and 
precursor serves that purpose as well as any other. Assuming that M@. precursor 
will be used, for convenience, as a species, it will be necessary to define it roughly, 
though it is impossible, on account of its zonal variations, to give a diagnosis 
which shall be at once accurate and concise. 

While the-smaller and narrower forms of M. precursor agree in general 
outline, position of disc, position of peristome, and shallowness of ambital notch 
with MM. Leskei, they differ from this species in having a varying degree of 
ornamentation of the interporiferous area, ranging from the ‘sutured’ to the 
‘subdivided’ type, instead of a perfectly smooth area. Further, the anterior 
peristomal segment is always broad and jointed in M. precursor, and the 
labral plate more or less freely tuberculated. The converse holds good in 
M, Leskei. 

On the other hand, M. precursor differs from M. cor-testudinarium, Gldf., in 
being narrower and, as a general rule, smaller. We have here no type of ambu- 
lacrum which is singular to one form, asin the case of M. Leskei, for all the types: 
of ambulacra, from ‘sutured’ to ‘subdivided,’ are shared by MZ. precursor and 
M. cor-testudinariwm alike. It may be stated, however, that according to the 
rule that broad forms have deep ambulacra, we find that, on the whole, MW. cor- 
testudinarium has deeper ambulacra than M. precursor, and that, owing to the 
increased depth, the subdivided ambulacra are mostly associated with the broad 
form.—June 7th, 1899.| 


Vol. 55.1 DR. A. W. ROWE ON THE GENUS MICRASTER. 497 


Many species of Wccraster were described when the zonal geology 
of the Chalk was unknown, or in its infancy, and though several of 
these forms have since been allotted to definite horizons, it is clear 
that their descriptions would have been of greater value had their 
authors possessed a more extended knowledge of the genus as a whole, 
and had they looked upon these forms rather as strong varieties, 
occurring at certain horizons, than as definite specific entities. This 
necessarily haphazard method of the older writers explains the naming 
of several closely related forms, which are unworthy of a specific title ; 
for had they been able to examine hundreds of zonally-collected 
specimens, they would have been chary of making abrupt specific 
distinctions, where gentle transition from one form to another is 
the invariable rule. 

In reviewing this Protean genus, just as in the case of the 
Terebrutule, it would be easy to place a series on a long table, 
and to show an almost imperceptible transition from one form to 
another, and yet, from that same series, to pick out specimens which 
would serve as distinct museum-types of the several well-known 
species. And after ali, save in the cases where the environment of the 
urchin may have been often or abruptly changed, this is exactly 
what one would expect. Ifthe role of the field-worker and the study- 
worker had been more frequently combined in the same individual, 
we should have had fewer unreliable species. 

Here we have a most prolific and plastic genus, prone to the 
formation of marked varieties at any given horizon, and it is only 
by handling a large series of examples that one can arrive at the 
true value of these various species and varieties, and of their mutual 
relationship in the evolution of the genus. 

One suggestive and practical point, which rigid zonal collecting 
brings out, is that the actual conditions of existence at a given 
horizon have at their acme so modified the evolving form that the 
features are easily identified in the field, and become so helpful 
as zonal guides that one can tell, with something akin to actual 
certainty, from which zone a Micraster is derived. It is a matter 
for congratulation that the limits of the zones, as hitherto defined, 
coincide in a remarkable manner with the presence of well-marked 
groupings of the characters of the Micraster-test, so that all previous 
work in the separation of the zones not only stands good, but is 
greatly strengthened by this further study. 

Another dominant fact, which is elicited by an enquiry based on 
extensive zonal collecting, is that true species and strong varieties 
cannot be, save in rare instances, picked out indiscriminately from the 
different horizons; nor can they be characterized as sharply-defined 
and separate entities, but must be regarded as mere landmarks 
in the lite-history of the genus. To arrive at any true apprecia- 
tion of their value, both as to the validity of their claim to specific 
distinction and as to their usefulness as zonal guides, one must. 
examine the facies of the genus in each horizon, and then one cannot 
fail to be impressed by the fact that passage-forms are the rule, and 
that sharply-defined and typical species are the exception. It is 

Q.J.G.58. No. 219. 2k 


498 DR. A. W. ROWE ON THE GENUS MICRASTER. [ Aug. 1899, 


the horizon, and not the species, which rules the issue ; the species 
are but culminating points of certain dominant horizonal characters. 

A convincing proof of this contention is found in the upper part of 
the Micraster cor-anguinum-zone, where broad forms—contrary to all 
one’s preconceived ideas—are equally as common as narrow forms; 
and yet a careful analysis of every broad form fails to furnish a single 
example which can be called M. cor-testudinarium. The conditions 
of existence were so powerful that MW. cor-testudinartum could not 
persist as such in the higher zones, and it became merely a broad 
variety of M. cor-anguimum auctorum, with high-zonal characters, 
just as M. cor-testudinarvum, Goldfass, in the low zones, is only a 
broad variety of M. precursor. This is but another instance of the 
unity of the scheme of evolution in this genus, for we find broad 
varieties of narrow forms in every horizon, a the lowest to the 
highest. 

We have persisted for so many years, adding species to species, 
till many of the accentuated forms have now been described, and the 
synonymy has already reached burdensome proportions. Untortu- 
nately, so prone is this plastic genus to variation that the material 
for elevating mutations into species is by no means exhausted, and 
one is compelled to ask whether the time has not come to call 
a halt, to examine our position, and to consider whether there is 
no way out of a situation which is rapidly becoming untenable. 
Two courses are open to us. We must either follow the Continenta 
school, and make every prominent form a species, on the plea that 
every minute variation must be ticketed and pigeonholed, irrespective 
of the fact that such variations may be valueless as zonal guides; 
or we must strike out in the new direction to which English thought 
is certainly tending, and study the facies of the genus as a whole, 
carving out broad zoological groups, and allowing the horizon, and 
not the species, to be our criterion. In this way, all valid species 
and varieties will be retained, and those which are valueless as 
zonal guides will soon find their level, and sink into the oblivion of 
an unwieldy synonymy. 

To such a scheme as this the writer unhesitatingly gives his 
allegiance, for in it we may hope to trace the evolution of the genus 

-as a whole, and each prominent feature of the test in particular; and 
in it the neglected, but equally valuable passage-form, will receive 
its due recognition. 

Unless a genus like Micraster is attacked from the zoological 
standpoint, all trace of continuity and evolution is lost, and the 
whole enquiry fritters away into an attempt to learn by heart the 
names and shapes of certain marked forms, disconnected, and with- 
out meaning. The clue to the whole question lies in the narrow zone 
of Holaster planus, for if we can unravel the tangle in this zone all 
the rest becomes clear. In this zone we find JW. cor-bovis, M. Lesket, 
M. precursor, M. cor-testudinarzum, and but for the interporiferous 
area of the paired ambulacra it would be almost impossible to 
distinguish the latter two from the same forms in the zone imme- 
diately above. 


Vol. 55.] DR. A. W. ROWE ON THE GENUS MICRASTER. 499 


II. A Review or tHE Evouvurtion or Specrat FEATURES OF THE TEST 
IN ALL Forms AND AT EACH Hortzon. 


This analysis will show how completely the conditions of existence 
in the various zones dominate all the special characters of the test, 
and thus what have been hitherto considered purely specific cha- 
racters, may now be regarded from the much broader standpoint of 
horizonal influence, finding their true level in the scheme of pro- 
‘gressive evolution. 

The percentages are given for all the forms collectively, as con- 
tained in each zone, except in certain cases where a species or 
variety is particularly specified. To clear the ground, before dealing 
with the species and varieties of the genus, it may be well to pass in 
review those features of the test which experience has shown to be 
useful as guides to horizon ; and at the end of this detailed review 
will be found a Tabular Summary (pp. 512-513), which will show 
at a glance the progressive evolution of each character. Only those 
features of the test with which it is necessary to deal in detail will 
be mentioned now. 


Interporiferous area.—In 1855, Hébert made observations 
on the ambulacral plates, and considered that he had found therein 
a guide to distinguish the different species. His figures appear in a 
paper on the Meudon Chalk, but there seems to be no text to 
elucidate the plates.’ 

From an entirely different standpoint—that of horizon—the 
present writer also attaches importance to the interporiferous 
portion of these plates, and, to facilitate reference, figures are given 
of five distinct types of the interporiferous areas, which, together 
with the other features of the test, will be found most useful in 
determining the horizon from which any given example is derived. 

With the exception that the smooth area is found only in the 
zones of Rhynchonella Cuvierr, Terebratulina gracilis, and Holaster 
planus, and that it indicates either Mocraster cor-bovis or M. Leskei, 
these areas have no value in the determination of species, as they are 
really an index of horizon. Their true interest lies in the fact that 
they assist in marking the passage from one form to another, and 
that they throw a side-light on the evolution of the different varieties 


of the genus. 


For the purpose of illustration, this interporiferous area is divided 
into five classes—‘ smooth,’ ‘ sutured,’ ‘ inflated,’ ‘ subdivided,’ and 
‘divided’ (Pl. XXXVI, figs. 1-8). 


The smooth area is restricted in most English sections to 
M. cor-bovis and M. Leskei, and 20 per cent. of all forms from the 
zone of H. planus fall within this category. Practically, all the 
specimens from the zones of Lh. Cuviert and T. gracilis are of this 


1 Foss. de la Craie de Meudon,’ Mém. Soc. géol. France, ser. 2, vol. v 
(1855) pl. xxix. 
( 2x2 


500 DR. A. W. ROWE ON THE GENUS MIcRASTER. [ Aug. 1899,. 


nature, and the smooth area is never found above the upper limit 
of the zone of Holaster planus—a point which is most useful when 
working in the field, in the absence, or rarity, of examples of H. planus. 


All the areas in this class have the sutures so faint that they are 
unrecognizable with a lens, and even in the case of Micraster Lesket 


there is no perceptible granulation of the smooth central portion 
(Pl. XXXVI, figs. 1 & 2). 


The sutured area is confined to the zone of H. planus, as- 
44 per cent. are classified under this heading in that zone. Itis very 
occasionally found in the Terebratulina gracils-zone, but never in 
that of Micraster cor-testudinariwm. The interporiferous area in this- 
class has its sutures more or less plainly visible with a lens, though 


to the naked eye they generally look smooth. There is no ornamen- 


tation of the plates, and at most they are only faintly granular, but 
they are always perfectly flat. 

This type of area is chiefly observed in the passage-form from 
M. Lesker to M. precursor, and it is also found in many examples 
of the WM. cor-testudinarium that occur in this zone. The smooth 
and sutured areas are, then, quite characteristic of the zone of 
H. planus, and are never found above the upper limit of that zone. 
(Pl. XXXVI, fig. 3). 


The inflated area is associated with the subdivided form in: 
the zone of MM. cor-testudinarium, and these two forms are charac— 
teristic of this zone. In this bed the inflation of the area is always 
strong, and is in the form of coarsely granular pads, which meet and’ 
dovetail in the middle line. About 50 per cent. are of this type. 

In the H. planus-zone 30 per cent. are of this nature, but the 
inflation is much weaker and fades away into the sutured form, 
giving a perfectly easy transition from the flat to the raised area in’ 
this single zone (Pl. XXXVI, figs. 4 & 5). 


The subdivided interporiferous area is characterized by very 


tumid and strongly granular plates, which slope sharply to the 
middle line, thus giving a deep and angular ambulacrum. The 


slope is interrupted at the inflation of the interporiferous plates, but 
the fall is then continued again as sharply as before, giving the 
appearance of a trench within a trench. To the naked eye it 
looks as if the interporiferous plates were entirely separated in the 
middle line, but examination with a lens shows that it is only the 
tumid upper portions of the plates which are separated, and that. 
the bases are in actual contact. This description will suffice for 
all examples in the low-zonal series. In the high-zonal series, 
however, the central furrow is not nearly so marked, owing to the 
fact that the ambulacral walls are much less steep. In well- 
preserved specimens it will be noted that the granules of the 
interporous ridge pass on to the interporiferous area, as will be 
demonstrated in the description of the interporous ridge. This is,. 
of course, an entirely high-zonal feature (Pl. XXXVI, fig. 7). 


Vol. 55-1 DR, A. W. ROWE ON THE GENUS MICRASTER, 501 


The subdivided and strongly inflated types are characteristic 
of the zone of Micraster cor-testudinarium, but they are also seen in 
the lower part of the M. cor-anguinum-zone. The subdivided form 
is more strongly represented in the M. cor-testudinarwwm-zone at 
Beachy Head than it is in the same horizon at Beer Head and Dover, 
but the difference is not sufficient to alter the conclusions herein 
stated (Pl. XXXVI, fig. 6). 


The divided area is never found in the Holaster planus-zone, very 
occasionally (barely 3 per cent.) in the WM. cor-testudinarium-zone, 
in about 20 per cent. of the forms in the lower third of the M. cor- 
anguinum-zone, while above the latter level it becomes the common 
form. This type differs from the subdivided variety by reason of 
the completeness of the furrow between the central tumid portions 
-of the ambulacral plates, which separates the base of the inflations as 
well as the top, giving a vertical central trench, just as if a cut had 
been made with a saw. 

At the first glance, the divided area in the zones of WM. cor- 
destudinarium and M. cor-anguinum differs considerably, but in 
reality the method of division is the same in both, and the apparent 
Jack of similarity is due to the fact that the ambulacrum in the 
former is deeply excavated, and that in the latter it is shallow. 


At this point it may be useful to note that the general shape 
of the ambulacra varies in the different beds, for in the zones 
of 7. gracilis and H. planus, where the smooth, sutured, and 
gently inflated areas predominate, the general form of the 
ambulacrum is that of a flat trough; while in the MW. cor-testudi- 
narium-zone, and in that of MW. cor-anguinum (lower third of zone), 
the excavation is deeper, more strongly sloped, and much more 
angular. As soon as we pass above the low-zonal limit, we find 
that the ambulacra become much shallower, so that in many instances 
they are almost flush with the surface of the test. 

It is worthy of mention also that there is a progressive scale of 
inerease in the size of the interporous ridge and of its granules, 
till, when we reach the high-zonal forms, we find the linear series 
of granules very prominent. In connexion with this feature it 
should be remarked that in the low-zonal forms the linear granules 
cease abruptly at the inner row of pores, whereas, in the high-zonal 
forms they are continued on to the interporiferous plate, curving 
round the whole margin of it in the form of a hook (Pl. XXXVI, 
fig. 7). A foreshadowing of this last-mentioned condition may be 
found in one or two granules which curve round below the inner 
row of pores. This feature is seen in Pi. XXXVI, fig. 5, which 
represents a specimen derived from the M. cor-testudinariwm-zone. 

While dealing with the paired ambulacra of the superior surface, 
it may be of interest to refer to the ambulacra of the inferior 
surface. Five avenues (double rows of paired pores) radiate from 
the mouth—two posterior, two lateral, and one anterior; and two 
gingle rows are found just inside the short vertical arms of the 


502 DR. A. W. ROWE ON THE GENUS MICRASTER.  [ Aug. 18909 


sub-anal fasciole. The disposition of the oral series of avenues may 
be seen on Pl. XX XIX, figs. 2 & 3. A glance at the figure of the 
lateral avenue of Micraster cor-bovis (Pl. XX XIX, fig. 4) will show 
that the paired pores are covered in by a strong arch. This feature 
is best seen in this species on account of the smoothness of the test,. 
but it is invariably found in Micraster, and is also seen in Hemuaster,, 
Holaster, and Echinocorys. So far as Micraster is concerned, the 
avenues become more obscure the higher one mounts in the zones, 
on account of the progressive elaboration of the epistroma. 

The single ambulacrum of the superior surface offers a striking 
similarity to the ambulacra of the inferior surface, for the ‘ granule’ 
that separates the oblique paired pores appears in reality to be a 
double arch, which is commonly fused by the taking-up of carbonate 
of lime in fossilization, and so forms the so-called ‘granule.’ This: 
feature can be studied only in well-preserved examples, such as those 
from Gravesend, and is clearly brought out in Pl. XX XVII, fig. 5. 
It is, however, found. in all species and varieties of Micraster, and its 
absence is merely due to imperfect preservation. It will be seen that. 
the outer division of the arch is much thinner than the inner portion. 

In very well-preserved examples of JZ. cor-bovis one may detect. 
the distant ambulacral openings spreading down over the side of the 
test from the end of the ambulacral groove. These pairs of pores: 
are separated by an arch, just as in the single ambulacrum. 

Between the two rows of pores in the case of the upper six or 
seven pores of the paired ambulacra, a similar arch is thrown out. 
This arch looks like a granule in most cases, but in rare instances 
the double arch can be made out. After the sixth or seventh pore 
it disappears as an arch, but it passes in the form of a trumpet- 
shaped expansion over the outer side of the inner row of pores. 
This feature is seen in Pl. XXXVI, figs. 5 & 6. 


Single ambulacrum.—Though not nearly so useful a zonal 
guide as the paired ambulacra, the single ambulacra show conclu- 
sively that they also: share in the progressive evolution of the test. 

In Pl. XXXVII, fig. 1, is seen the feebly granular and almost. 
smooth interporiferous area of I, cor-bovis, while fig. 2 gives a slight 
increase of granulation in the case of MW. Leskei, neither of them 
showing the least trace of the sutures of the plates. Fig. 3, from 
an example of J. precursor in the H. planus-zone, again leads up 
to a definite granulation and suturing of the central area, which 
is intensified in fig. 4, representing an example of M. precursor 
from the M. cor-testudinarium-zone ; and the climax is reached when 
we examine fig. 5, taken from a beautifully-preserved specimen 
of M. cor-anguinum from the zone of the same name. In this 
last we notice the double arches between the pores, the increased 
granulation of the interporous ridge and of the interporiferous 
plates, with a heaping-up of the edges of the latter plate in the 
middle line. The paired pores are quite sunk by this elaboration 
of the epistroma in the lower end of the ambulacrum. 

No name has been given to the different varieties of the single 


PMols 55. DR. A. W. ROWE ON THE GENUS MICRASTER. 5038 


ambulacra, for the reason that the features are not, as a rule, suffi- 
ciently prominent or well preserved to warrant one in burdening the 
mind with unprofitable detail, which cannot be used in the field. 


The conclusions which one may draw from these observations 
on the interporiferous area are clearly brought out in the per 
centages quoted. It will be seen that Micraster cor-bovis and 
M. Leskei alone have the smooth central area, and that this, together 
with the sutured and gently inflated type, is distinctive of the 
Holaster planus-zone ; that the strongly inflated and the subdivided 
areas are characteristic of the zone of M/Z. cor-testudinarium and of 
the base of M. cor-anguinum; while the divided area is typical 
of the upper part of the I. cor-anguinum-zone. 

When we come to deal with the special features of the various 
‘species,’ it will be evident that in the interporiferous area we have 
a reliable guide to horizon. It will be shown that there is no 
difference in the general facies of M. precursor aud M. cor-testudt- 
narium in the zone of H. planus, or in the same forms when they 
occur in the zone of M. cor-testudinarizum, nor do these forms occur 
more frequently in one zone than the other; and yet a glance at the 
interporiferous area will reveal with practical certainty from which 
bed each form is derived. Further, this area is the chief means of 
marking the passage-forms from one species to another, and therefore 
of showing the unbroken continuity in the evolution of the genus. 


Length and breadth.—In the Terebratulina gracilis-zone we 
find chiefly long forms, and these are notably longer than in any 
other zonal series of. Micraster, on account of the preponderance of 
M. cor-bovis ; and while, even in the case of M. cor-bovis, there is a 
tendency to establish a broad and a narrow form, the breadth never 
actually equals the length, as it not uncommonly does in other 
species in the zones above. 

In the other low-zonal beds the narrow forms strongly pre- 
dominate, and it is only when we reach the high-zonal series, in the 
upper part of the M. cor-anguinum-zone, that we find an equal 
number of broad and narrow forms. It appears to be beyond doubt 
that in each zone there are broad varieties of the narrow forms, 
and that the proportion of broad forms increases as we ascend in 
the Chalk-zones. 


Height.—All low-zonal forms, with rare exceptions, are de- 
pressed, and it is not until we reach the base of the M. cor-anguinum- 
zone that elevated forms begin to be strongly represented. Above 
that limit tall forms are the rule, but very broad and large examples 
are not infrequently depressed. There seems to be a marked ten- 
dency, even so high up as the top of the MW. cor-anguinum-zone, for 
the broad forms to be depressed, and thus suggest features which 
have always been considered characteristic of WM. cor-testudinarium, 


Goldfuss. 


504 DR. A. W. ROWE ON THE GENUS MICRASTER.  [Aug. 1899, 


Superior surface.—To facilitate reference, the forms which 
slope evenly and gently, back and front (asin Pl. XX XV, line iv, 
fig. 2), are called ‘ flat-arched’; and to those which have a sharp 
and straight fall from apex to anus (as in Pl. XXXYV, line iii, fig. 6) 
the term ‘ gibbous’ is applied, in contradistinction to those which 
have a curved posterior fall, ike that in Micraster Bronyniarti, 
Hébert, in WM. beonensis, Gauthier, and in M. intermedius, Bucaille. 
The last-named shape is seen in Pl. XXXYV, line i, fig. 3, and in 
fact in fig. 3 of all the lines on that plate. It will be seen, on 
reference to Pl. XX XV, that these outlines, together with other 
definite profiles, run right up through the zones, and a full survey of 
them will be given when the plate is discussed in detail (p. 509). 

It is of interest to note that these types of superior surface are 
restricted to no one species or variety, and that we see them 
all exemplified in undoubted examples of M. cor-bovis, M. Leskei, 
M. precursor, M. cor-tesiudinarium, M. cor-anguinum, and MM. cor- 
anguinum var. lator; further, that we may find each or any of 
these species with a slight posterior rise, thus foreshadowing the 
strong carination, which is one of the features of the high-zonal 
Micraster. The high-zonal forms are merely a repetition of the 
low-zonal series, with greater development of special features. 

Another characteristic is that in the low-zonal forms the anterior 
slope is gentle and rounded, and that in the high-zonal forms it is 
very sharp. This sharp slope is well seen in the Gravesend 
examples on lines vi and vii in Pl. XX XV: here, again, the same 
progressive development is noted. 


Rostrum and carina.—In the Terebratulina gracilis-zone, in 
the case of M. cor-bovis, both are absent; the rostrum in the zone of 
Holaster planus is absent in about 90 per cent.; in the MW. cor- 
testudinariwm-zone in about 80 per cent.; in the base of the WZ. cor- 
anguinum-zone it becomes more developed; and in the high-zonal 
forms it 1s a common feature. 

The carina in the H. planus-zone is absent in 72 per cent., slight 
in 20 per cent., moderate in 7 per cent., and strong only in 1 per 
cent.; in the M. cor-testudinarium-zone it is absent in 6U per cent., 
slight in 32 per cent., and moderate in 6 per cent.; in the base 
of the M. cor-anguinum-zone it notably increases, and in the high- 
zonal forms it is one of the conspicuous features of the test. It is 
worthy of note that the development of the carina is always in 
advance of that of the rostrum; the latter is, in fact, quite a late 
development. 

Again we are compelled to notice a progressive evolution of a 
feature from the low to the high zones. 


Apical disc.—The Tabular Summary (pp. 512-518) gives all 
the necessary percentages, and shows a marked progressive dimi- 
nution of the anterior excentricity. 

No attempt has been made to figure or describe the progressive 
granulation of the disc, as this feature of the test is commonly 


Vols 55a] DR. A. W. ROWE ON THE GENUS MICRASTER. 505 


marred by excessive deposit of carbonate of lime. It may be stated, 
however, that many photomicrographs have been made of the disc, 
and that the same progressive ornamentation may be traced as that 
found in the ambulacra; still, for the reason given, the disc does 
not lend itself to rapid examination in the field, and it has been 
discarded as an unnecessary detail. It may be mentioned, however, 
that one finds varying degrees of divergence in the posterior genital 
pores, and that the four pores are sometimes decidedly unsymmetrical. 
I do not follow Stolley' in regarding this asymmetry as a specific or 
varietal feature, but strongly dissent from such a course. 


Highest point of test.—Here, again, there is a steady pro- 
gression, which is only what would be expected, as the highest point 
becomes more posterior in proportion as the carina becomes more 
developed. 


Anteal sulcus and ambital notch.—All low-zonal forms 
have a shallow suleus and notch, and they may be absent in 
Micraster cor-bovis and M. Leskei. 

This shallowness is an horizonal and not a specific feature; for 
at is not more marked in MM. cor-testudinarium, Goldfuss, than in 
M. precursor. There is little or no difference in the degree of 
shallowness in the Holaster planus and M. cor-testudinarium-zones, 
but as soon as one passes into the base of the M. cor-anguinwm-zone 
the notch and sulcus both deepen, and in the high-zonal forms they 
are almost invariably deep. The only exception to the last statement 
will be found in the broad high-zonal varieties, the W. cor-anguinum 
var. latior of this paper, which have a tendency to preserve the 
hallow notch. Once more we notice a progressive increase of a 
feature of the test. 


Position of mouth.—Here is another unbroken progression 
from low-zonal to high-zonal forms, and the table clearly brings 
out the average distance from the bottom of the notch. 


Labrum.—tThe progressive increase in this feature is also well 
seen in the Tabular Summary. Its rudimentary condition is observed 
in WM. cor-bovis and in WM. Leskei, and one is even taken a stage farther 
back in M. Sancte-Maure, Gauthier, of the Rhynchonella Cuvieri- 
zone, where the labrum is practically non-existent. 

It is feebly developed in all the species and passage-forms of the 
zones of H. planus and M. cor-testudinarium, and it never covers-in 
the peristomal orifice until we reach the base of the M. cor- 
anguinum-zone ; but in the high-zonal forms it becomes very thick 
and prominent, and generally projects well beyond this orifice. 


Labral plate.—In all low-zonal forms the tubercles abruptly 
stop short of the labral tip, and no secondary tubercles are seen 


par rede Schl.-Holsteins,” Mitth. Mineral. Inst. Univ. Kiel, vol. i (1892) 
p- 191, 


506 DR. A. W. ROWE ON THE GENUS MICRASTER. [ Aug. 1899, 


on the anterior end of the labral plate. In all high-zonal forms, 
on the contrary, the tubercles are continued almost to the end ot 
the labrum, and secondary tubercles and granules at the extreme 
end of the labrum are the rule. 

The shape of the labral plate in low-zonal forms is broadest where 
it joins the plastron, and it tapers to a point towards the labrum, being 
roughly triangular (Pl. XX XVII, fig. 8). In the high-zonal forms, 
on the other hand, the labral plate is, as a rule, narrowest at the 
plastronal end, keeping a nearly equal width until it approaches 
the labrum, where it notably expands (Pl. XX XVII, fig. 9). 

The arrangement of the tubercles on the labral plate is generally 
irregular in the low-zonal forms, and more symmetrical in high- 
zonal forms, tending in the latter to constitute a regular multi- 
columnar series; moreover, in Micraster Leskei there is a hiatus 
between the plastronal and the labral tubercles, and the same 
statement applies to the narrow ‘sutured’ forms, however large 
they may be, which form the transition-series between M. Leskev 
and the Holaster planus-type of M. precursor. In the H. planus- 
types of MW. precursor and M. cor-testudinarium, on the other hand, 
we find in a quarter of the number a merging of the plastronal and 
labral tubercles into a continuous series; and in the same forms, in 
the M. cor-testudinarium-zone, the proportion in which the sets of 
tubercles merge becomes one third; while in the high-zonal forms, 
in the top of the zone of MW. cor-anguinum, the proportion reaches 
vearly a half. 

In M. cor-bovis the tubercles are grouped towards the labral tip, 
and are very few (Pl. XXXIX, figs. 2-5); in M. Lesker they are 
also few and irregularly placed along the length of the labral plate 
(Pl. XXXVITI, fig. 1); in the narrow ‘sutured’ transition-forms 
between M. Lesket and M. precursor, of the H. planus-zone, the 
tubercles are more abundant and more symmetrical; and the 
symmetry and abundance increase in the IM. cor-testudinarium-zone. 

The paucity and asymmetry of the series of tubercles in M. cor- 
bovis and M. Lesket are not evidences of immaturity, as they are 
found in the largest specimens of the two species; while, on the 
contrary, in the smallest examples of other forms in the H. planus- 
zone both the shape of the labral plate and the arrangement of 
the tubercles are quite different. The importance of this will be 
seen when we come to deal with MW. Leskei as a separate species. 


Tip of labrum.—tThis is a very characteristic feature. In all 
low-zonal forms there is a tendency for the tip to be smooth, and 
invariably it is strongly granular in all high-zonal forms. 

In M. cor-bovis and M. Lesket the labrum is rudimentary, and 
merely a projection from the smooth-ringed peristome. In the 
narrow ‘ sutured’ transition-form between M. Lesket and the 
HH, planus-type of M. precursor it is invariably smooth; whereas, 
in the M. cor-testudinarium-zone it is slightly granular in a third of 
the forms; and in the upper part of the zone of M. cor-anguinwm it 
is strongly granular in every instance, the granulation extending 
even to the upper surface of the labrum, inside the test. 


age an, a egy alee 


Vol. 55;] DR. A. W. ROWE ON THE GENUS MICRASTER. 507 


Peristome.— Micraster cor-bovis forms the type of the smooth, 
flat, unbroken peristomal ring, with no trace of divisions between 
the plates of the peristome (Pl. XX XIX, fig. 1), and we have an easy 
transition from this species into M. Leskei, where the ring is still 
prominent; but the subsequent separation of the peristomal plates 
is indicated only by slight nodulations in the outline, and in most 
instances even these may be wanting. The peristome is then seen 
as an unbroken raised ring (Pl. XX XVIII, fig. 3). 

From WM. Leskei into the narrow ‘sutured’ variety of M. pra- 
cursor of the Holaster planus-zone is the next stage, for here we 
find the labral tip and the peristomal plates adjoining it smooth and 
unjointed; while the anterior segment of the peristome, for the first 
time, shows indications of definite jointing between the peristomal 
plates (Pl. XXXVIII, fig. 4). Im all the other forms in the 
iT, planus-zone the labral tip is the only smooth part of the peristome, 
and the jointing of the anterior segment becomes more marked. This 
description is true, in an increased degree, for all forms in the zones of 
M. cor-testudinarium and M. cor-anguinum (Pl. XX XVIII, figs. 7-9). 
In the M. cor-anguinum-zone, in addition, there is a tendency for 
the surrounding granulation to invade the ends of the peristomal 
plates which are farthest from the oral cavity (Pl. XX XVIII, fig. 9). 
There is also a marked tendency for the anterior peristomal plate 
to become longer, and there is a progressive increase in this direction 
from the AH. planus-zone to the M. cor-testudinarium-zone, and from 
the latter to the zone of WM. cor-anguinum. The granulation invades 
the margins of the plates in the same manner as in the ambulacra 


(Pl. XXXVI, fig. 7). 


Periplastronal area.—tThis is the broad band which surrounds 
the plastron and labral plate, separating them from the general 
tuberculated surface of the base. The distinction between JV. cor- 
bovis and M. Leskex with respect to this area is brought out clearly 
in Pl. XXXIX, figs. 4 & 5, and in Pl. XXXVIII, fig. 1, and the 
differences are formulated in the description given of WM. cor-bovis 
on p. 521. 

In all low-zonal forms the granulation is fine, becoming coarser 
as we reach the top of the MW. cor-testudinarium-zone ; while at the 
base of the M. cor-anguinum-zone it is notably stronger, and in 
the high-zonal forms it reaches its maximum, and is there invariably 
mammillated (Pl. XX XVII, figs. 6-9). 


Depth of ambulacra.—The progression from the deep low- 
zonal grooves to the shallow high-zonal grooves is plainly brought out 
in the Tabular Summary (pp. 512-513), and is diagrammatically 
depicted in the vertical sections of the ambulacra given below each 
photomicrograph on Pl. XXXVI. The high-zonal exceptions to this 
rule are found only in the broad forms, such as the WM. cor-anguinum 
var. latior of this paper, and M. glyphus, Schliiter, of the zone of 
Belemnitella quadrata. This merely illustrates the tendency of broad 
forms, in all zones, to have deeper ambulacra. 


508 ‘DR. A. W. ROWE ON THE GENUS MICRASTER.  [ Aug. 1899, 


Length of ambulacra.—tThere is a progressive increase in the 
length of the paired ambulacra as one ascends in the Chalk-zones. 
Micraster cor-bovis has them remarkably short, and they are short 
also in M, Lesker.; after that the increase is gradual. M. brevis, 
Desor, would be an exception to this rule; but the writer has 


never found it in England, nor has he met with any record of its 
occurrence. 


Curve of posterior ambulacra.—The curve is notable in 
M. cor-bovis, less in M. Leskei, and becomes gradually less until one 
reaches the top of the MZ. cor-anguinum-zone, where in a definite 
percentage of narrow forms the posterior ambulacra are quite straight. 
Exceptions will be found in the broad high-zonal forms, such as 
M. cor-anguinum var. latior and M. glyphus. 


Interporous ridge.—This may be absent in MW. cor-bovrs, and 
is always feeble in VM. Lesker; after these two marked forms die 
out there is always a progressive increase of the granulation of the 
ridge in other forms as one ascends the zones. The extension of 
the granulations on to the interporiferous area of the forms at the 
top of the WM. cor-testudinarium-zone and in the MW. cor-anguinun- 
zone has already been mentioned (Pl. XXXVI, figs. 5 & 7). 


Sub-anal fasciole.—Feeble in M. cor-bovis, and only mode- 
rately developed in all low-zonal forms; strong, on the contrary, in 
high-zonal forms. In the low-zonal forms there is always a 
tendency to a contraction in the short diameter, and in the high- 
zonal series it is almost always broad and straight. The transition 
from zone to zone is exemplified in Pl. XXXIX, figs. 5-7, and 
the contrast clearly brought out. 


Intra-fasciolar bosses.—In high-zonal forms the narrow 
posterior end of the base generally ends in two marked prominences, 
which are situated within the fasciolar area. These are absent in 
all low-zonal forms. 


Latero-oral ambulacral grooves.—Spreading out on either 
side of the peristome are two grooves, each containing an avenue of 
arched pores. These grooves are a marked feature of all low-zonal 
forms, and are but slightly indicated in the high-zonal series. 


Inflation of plastron.—This is ill-marked in low-zonal 
forms, and the same applies to the labral plate; but in high-zonal 
forms the inflation, in both cases, becomes more marked. 


Primary tubercles of base.—In JM. cor-bovis the areolar 
circle is made up of a scanty and scattered ring of large granules 
(Pl. XXXVIILI, fig. 6); in WM. Lesket it is much stronger, and offers 
a certain guidance in determining the two forms (Pl. XXXVIII, 


~~ aya 


Vol. 55.] DR. A. W. ROWE ON THE GENUS MICRASTER. 509 


fig. 2); above Micraster Leskei the granulation is present in an 
ever-increasing (degree. 


General shape of the test.—The overwhelming importance 
which most writers attach to this point is obvious from the nature of 
the many ‘species’ figured, for in not a few instances a profile- view 
only is given, and, where the base is shown, it is generally drawn 
to demonstrate the contour of the ambitus and the position of the 
peristome. In the majority of instances it would be impossible to 
determine from the figure from which zone a specimen is derived, 
and unless a figure tells us this fact it is practically valueless, for a 
Micraster which is not accurately zoned is not worth the trouble of 
picking out of the Chalk. 

We know that in living forms the mere profile varies greatly, 
even within the limits of a definite species ; therefore it is difficult 
to understand why, merely because the creature happens to be pre- 
served in the fossil state, a simple depression or elevation of the test 
should suffice for the erection of a specific type. 

Ifa notably depressed form such as M. Normannie, Bucaiile, of the 
Holaster planus-zone, for instance, has other characters which mark 
it out from the regular facies of the genus Micraster of that zone, 
then, by all means, make it a species ; but if a flattened shape is its 
only attribute, and if the same shape is found in forms from neigh- 
bouring zones, then it is clear that a species has been coined on 
insufficient grounds. To show the utter futility of manufacturing 
species in this manner, Pl. XXXV reproduces a photograph of a 
graduated series of Micraster of different varieties and species, all 
accurately zoned, arranged in rows on glass shelves. 

Allusion has been made before to the fact that there is a 
broad and a narrow form of each species, though WM. cor-bovis and 
M., Leskei never yield examples in which the length and the breadth 
are quite equal. Take the forms from the H. planus and M. cor- 
testudinarvwm-zones, as shown in profile on Pl. XXXYV, and it 
will be seen that we can construct a complete scheme of varying 
shape for each species or variety, be it of the long or broad type, 


and that this scheme will apply to every species described in these 
zones. 


It may be desirable at this point to give a full explanation 
of Pl. XXXV. In the first place, the fossils are photographed so 
as to be as nearly as possible half the natural size; for instance, 
the large M. cor-bovis, at the right end of line ii, is exactly 80 mm. 
long. This example is included, so that a comparison may be made 
with the giant variety figured by Forbes and the much commoner 
small type (line i, figs. 1-4). The lines must be inspected from 
below upwards, in the order of the Chalk-zones. (It should be 
noted that some of the examples of MW. cor-bovis and M. Leskei were 
found in the upper part of the Terebratulina gracilis-zone) :— 


510 DR. A. W. ROWE ON THE GENUS MICRASTER. | Aug. 1899, 


line i. M. cor-bovis 1to4; M. Leskei 1'tod'. 

line ii. M. precursor (see p. 531). Zone of Holaster planus. 

line iii. MM. cor-testudinarium. 

line a uu sei at SY a | Zone of M. cor-testudinarium. 


line vi. M. cor-anguinum. ; 
line vii. M. canons var. latior. | Zone of MM. con-angam™am 
This plate is intended to show the contrast, and, at the same 
time, the continuity and affinity, which exist between the low-zonal 
and high-zonal series ; it is also intended to indicate the similarity 
in profile afforded by the broad and narrow forms in each zone, 
The dominant profile-shapes may be enumerated as follows :— 


(1) The very depressed form, with either straight or sloping posterior 
truncation—No. | in each line. This is the forma Normannie. 

(2) The less depressed form, with flat-arched upper surface—No. 2 in each 
line. This is the dominant precursor-form in the low-zonal series— 


the forma planidorsata. 

(8) The round-arched form, always a tall example, with carina forming a 
curved posterior falli—No. 3 of each line. This is the forma beonensis. 

(4) The form with a definite posterior rise from the apex to the posterior 
truncation, owing to the development of the carina—No. 4 of each 
line. ‘This is the forma carinata. 

(5) The gibbous form, with a straight fall from the apex to the posterior 
truncation. ‘This is a very interesting form, and it is worthy of note 
that every example here figured has a strong sub-anal fasciole. This 
is shown in No. 4 of the WM. cor-bovis series, and in No. 5 of all the 
other lines, including No. 5! of the WM. Leskei-group. Nos. 6& 7 also 
belong to this class, and are added to show the varying degree of the 
gibbous slope. It clearly indicates that there is no need for a gibbous 
Micraster to be a tal! one. ‘This is the forma giblosa. 


It will thus be seen that every zone, and every species and 
variety in that zone, shows a definite scheme of profile-shape in its 
micrasters, and that this scheme of shape may be faithfully repro- 
duced in neighbouring and allied zones, and be strongly reproduced 
in the more distant and higher zones. 

Though the general scheme for the high zones is seen to be the 
same as that in the low zones, there are certain added features to 
be noticed, such as the sharp anterior slope, the strong rise of the 
carina, and the development of a rostrum. These features are 
merely the outcome of a persistent evolution, and they in no way 
detract from the complete parallel afforded by the two series. 

-Tt would have been easy to add examples of other profiles, 
such as those shown in M. Bucailli, Parent, and M. turonensis, 
Bayle, and even of other prominent shapes noted by the writer; 
but this would have resulted in a considerable enlargement of the 
staging, and a consequent reduction in the size of the specimens 
figured. In any case, the five forms figured are incomparably the 
commonest, and they amply suffice to give point to the contention 
herein advanced. 

It is, then, abundantly clear that mere shape is the feeblest reed 
to lean upon in constructing a specific type, and that unless an 
urchin has other special features, which single it out from its fellows 
in any given zone, there is no ground for founding a new species. 


Noles5.| DR. A. W. ROWE ON THE GENUS MICRASTER. 511 


It is only by grouping the special features of the test that we can 
obtain any idea of the zone from which an example is derived, and 
it is only by the aid of these same special features that we can 
hope to arrive at the definition of a group, or what is infinitely 
more rare,a true and constant species. Thus, if in the zones of 
Holaster planus and Micraster cor-testudinarium, for instance, where 
deep ambulacra, an anterior disc, a posterior mouth, a feeble labrum, 
a thin sub-anal fasciole, and a shallow ambital notch are the in- 
variable rule, we were to find a depressed form which had shallow 
ambulacra, a central disc, an anterior mouth, a prominent labrum, 
a strong fasciole, and a deep ambital notch, we should be justified 
in giving it a specific title, in order that we might note the 
divergence from the dominant horizonal type. Anything short of 
this is a mere variety, unless, as in the case of JV. cor-bovis, in 
addition to the zonal features we find other superadded features 
which are peculiar to that type, and to that type alone. 


Angulation of ambitus.—tThis is an uncommon feature in 
low-zonal forms, and is only present, as a rule, in large, broad, and 
flat examples. It is more common in the high-zonal series, but is 
still confined to the same advanced and mature types, and this 
accounts for its presence in M. glyphus, Schliter. 


Now, granting that this detailed analysis of the separate features 
of the test is accurate, it may reasonably be asked whether these 
features afford sure guidance in determining the zone from which 
any given Micraster is derived. Furnished with this knowledge of 
detail, can we go into a quarry, or attack a cliff-section, pick 
out a few specimens of Micraster, and from this evidence alone 
decide the zone in which we are working? ‘This is a severe 
test, and one would not employ it in the field to the exclusion of 
other collateral evidence of associated fossils; but severe as the 
test may be, it is both practicable and effective. For instance, it 
is always possible to fix the junction-line of the zones of H. planus 
and VW. cor-testudinarvum by the form of the ambulacra alone, and 
it will be found. that the level at which the ‘sutured’ and gently 
‘inflated’ interporiferous area ceases is coincident with the disap- 
pearance of the guide-fossils H. planus and M. cor-bovis, and there- 
fore with the incoming of the MM. cor-testudinariwm fauna. Both 
H. planus and M. cor-bovis may be absent or rare, and then we 
should have to fall back on the gasteropods, which may also be 
absent; so that the Micraster is left to us as the only fixed quantity 
upon which we can rely. 

Though the ambulacra are generally sufficient in themselves as a 
guide, an inspection of the detailed analysis and of the Tabular 
Summary (pp. 512-513) willshow that there are other features of the 
test which one can join to the interporiferous area, and so make the 
determination more complete. Attention is called more particularly 
to the arrangement of tubercles on the labral plate, the length of the 
labrum and the nature of its tip, the conformation of the peristome, 
and the degree of granulation of the periplastronal area. 


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os DR. A. W. ROWE ON THE GENUS MICRASTER. [ Aug. 1899, 


Take another boundary-line—that between the zones of J. cor- 
testudinarium and M. cor-anguinum. The shape and general 
appearance of M. precursor and M. cor-testudinarium in their several 
zones are much the same to the casual glance ; but as soon as we enter 
into the base of the higher zone the ambulacra become shallower, the 
labrum longer, the tubercles of the labral plate more columnar in 
arrangement, the plate itself narrower at the plastronal end, the 
labral tip more granular, and the periplastronal granulation more 
mamumillated. 

So fully has the writer learned to depend on the various features 
of the test, which have here been brought forward in detail, 
that when Mr. W. Hill took to Margate some fifty specimens of 
Micraster, collected by his own hand from definite zones in various 
parts of England, each specimen was referred to its zone, and in 
not a few instances a suggestion was made as to the particular 
part of the zone from which the example was derived. A fossil 
can hardly be expected to afford more definite information than this. 
There is ground, therefore, for the assertion that the Micrasters 
alone will suffice for fixing the junction-line in the low-zonal series 
of beds. 

Marked as are the differences in detail between the low-zonal 
and the high-zonal forms, the actual features vary only within 
certain limits, and the difference consists merely in a progressive 
elaboration of the epistroma. Let it also be clearly stated that the 
difference between the various zonal types are not merely distinctions 
of the study, but that they can be readily and rapidly used in the field. 

When nearing a junction-line, it is the writer’s invariable custom 
to clean the Micrasters every 2 or 3 yards, and a stout brush 
and an ivory manicure-instrument are all that is necessary for the 
purpose. The ivory tool does not damage the test, as a knife would 
do, and the chalk can be bruised off the test with gentle taps of a 
light tack-hammer. 


TI. Mernop or MEASUREMENT OF THE TEST, WITH A SYNOPTICAL 
ConTRAST BETWEEN HIGH-ZoNAL AND Low-zonaL GENERAL 
FEATURES OF THE TEST. 


Before describing the various species and varieties as they are 
found in the sections mentioned at the beginning of this paper, it 
may be well to touch on the question of the method of measurement. 
The more one reads the literature of the genus Micraster, the more 
one is impressed by the difference in the measurements given, par- 
ticularly in the position of the apical disc. It has been impossible 
to find any mention of a fixed method of measurement, and in 
order that dimensions given in this paper may be capable of being 
checked by other observers, the plan herein adopted is set forth. 
At Dr. Gregory’s suggestion, a millimetre-scale was used, made with 
a fixed and a sliding vertical arm, on the principle of the shoe- 
maker’s measure. Neither the plan, adopted by Forbes and Wright, 
of using fractions of the English inch, nor that of A. d’Orbigny, who 
estimates the breadth and height asso many hundredths of the length, 


Viole 55.1 DR. A. W. ROWE ON THE GENUS MICRASTER. 515 


appeals to me as universally applicable ; and therefore a plain milli- 
metric measurement has been adopted as being more generally useful. 

The length is taken by dropping the specimen between the 
vertical arms, and measuring from the most prominent anterior 
and posterior points. It will thus be seen that the anterior 
measurement is taken from the anterior inflations, and not from 
the bottom of the ambital notch; and that the rostrum, when 
it exists, is designedly included in the posterior limit. This is done 
because the rostrum is not a meaningless excrescence, but has 
distinct value as an index of horizon. 

The breadth is measured at the greatest transverse diameter, 
and the height at the highest point of the Mcraster, independently 
of the fact that the point in question is probably not the apical disc. 
Here, again, the position of greatest height is not without its 
- meaning, for in the lower zones it is either at the apex or immediately 
behind it, and in the higher zones it is much farther back, on account 
of the development of the carina. 

The position of the apical disc is obtained by placing each end of 
the specimen in turn squarely against the fixed vertical, and laying 
a small millimetre-measure across the top of the Wicraster. 

The position of the mouth is not taken from a line drawn across 
the notch from the anterior inflations, but from the bottom of the 
notch itself, and a glance at an example from the zones of Holaster 
planus and Marsupites testucdinarius will make it clear that the depth 
of the notch is so different in the two forms that it would yield 
very misleading results. Practically, all examples from the lower 
zone have a shallow notch, and all from the higher zone a deep one, 
and on examining a hundred specimens of Micraster from the 
Marsupites-zone it was found that, by measuring from an imaginary 
line across the notch, the average position of the mouth was the same 
as in the low-zonal forms; whereas, in reality, the mouth in the 
low-zonal forms is invariably distant from the margin, and in the 
high-zonal series it is as constantly close to the notch. The mouth, 
then, is measured from the bottom of the notch to the anterior margin 
of the peristome. The anterior margin of the peristome is chosen 
because the labrum is often broken, and because its length varies 
greatly in the higher and lower zones, and is also useful as a guide 
to horizon. 


We may now consider the species and varieties found in the 
zones treated of in this paper :— 


iss < M. cor-bovis. aa 
M. cor-bovis. = S ieee oe 5 
M. Leskei. | 8.0 M. precursor. vs 

ic? M. cor-testudinarium. } * % 

) y ee M. precursor (in part). \ea 

M. precursor. | = 3 g M. cor-testudinarium (in part). | & SN 
OM. cor-testudinarium. | =: ae M. cor-anguinum auctorum. = § e 
en M. cor-anguinum var. latior, —) ee 


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Vol. 55. | DR. A. W. ROWE ON THE GENUS MICRASTER. 517 


It must be remembered that in the lower 80 feet of the zone of 
Micraster cor-anguinum we reach the point where the high-zonal 
series begins to divide from the low-zonal series. Without the aid 
of the special features of the test it would be impossible to dis- 
tinguish M. precursor and M. cor-testudinarium, as found in the 
base of this zone, from those found in the zone below. 

At this point it will be profitable to contrast the features of the 
test, as shown in the low-zonal and high-zonal series (see Table on 
the opposite page). Only the broad features are set forth, and the 
reader is referred to the Tabular Summary (pp. 512-513) and to § II. 
for a more minute description of the essential zonal details. 

It will, therefore, be noted that the low-zonal forms are the very 
antithesis of the high-zonal, of which MM. cor-anguinum auctorum 
is the type ; and it is abundantly clear that the specific types, how- 
ever marked and prominent they may be, are merely accentuated 
examples of certain characters seen in forms from definite horizons. 
This is especially noteworthy in the case of M. cor-testudinarwm, 
for the very features which Goldfuss, in his ‘ Petrefacta,’ sets forth 
as diagnostic of the species—shallow notch, deep ambulacra, and 
mouth distant from the border—are common to all varieties and 
species as far up as the top of the lower third of ube M. cor-anguinum- 
zone, breadth alone excepted. 

No attempt will be made in the present paper to deal with all the 
Continental forms described as occurring in these zones, as this 
description is essentially one of a typical English series. More- 
over, certain Continental forms are absent in England, and others 
are inaccessible. A few forms described from Continental deposits, 
which are also found in England, are essential to the illustration of 
the text, and will be noticed in the description of the Groups under 
which they fall. 


IV. Division or Micrasrer INto Grovps. 


For the sake of zoological and zonal interest I propose to divide 
Micraster into Groups. Bearing in mind the plasticity and 
abundance of the genus, it would seem that this is the only clear 
course to adopt, as by this means alone can the zoological sequence 
and the trend of evolution be traced. True species, and even 
prominent varietal types, are rare, and passage-forms and trivial 
variants are the rule. Nothing but a Group will embrace them 
all, and give to each series its correlative value. As this paper is 
not a monograph on the genus, a synonymy will be dispensed 
with. 

The Groups employed will be as follows :— 

1. Group of Micraster cor-bovis. 
2. Group of M. Leskei. 


3. Group of M. precursor (the low-zonal type). 
4, Group of M. cor-anguinum auctorum (the high-zonal type). 


It will be noticed that it has not been thought necessary to 
constitute a Group of M. cor-testudinarium, any more than one of 


518 DR. A. W. ROWE ON THE GENUS MICRASTER. [Aug. 1899, 


M. cor-anguinum var. latior, as they are here considered merely as 
broad varieties respectively of M. precursor and of M. cor-anguinum 
auctorum (see footnote p. 530). The reasons for establishing a 
separate Group for M. cor-bovis and M. Leskei will be set forth 
in the description of these species. 


(1) Group of Micraster cor-bovis. 


M. cor-bovis, Forbes, 1850. 


In Dixon’s ‘ Geology of Sussex,’ Ist ed. (1850) p. 342, pl. xxiv, 
figs. 3 & 4, Forbes describes this large form as ovate and slightly 
cordate, with a depressed upper surface, the highest point being 
in the anterior segment. He describes the apical disc as anterior, 
the anteal sulcus as shallow, the ambulacra as moderately excavated 
(the posterior being half the length of the anterior), and the 
primary tubercles on the dorsal and ventral plates as much scat- 
tered, and small for the size of the test. 

Length = 76 mm.; breadth = 65 mm.; height = 45 mm. 

In the Decades Geol. Surv. iil. p. 9, Forbes mentions, in addition, 
that the mouth is small, and the central area of the ambulacra 
smooth. 

Cotteau, ‘ Echinides fossiles de ?Yonne,’ vol. ii, p. 352, looks upon 
this species as a large variety of M. Leskei, and he dismisses the 
subject in a few lines, for he sees no reason to preserve it as a 
species. From his remarks it is clear that he could not have 
handled many examples, as he mentions hardly any of the salient. 
features of this strongly-defined species. 

Wright (‘ Brit. Cret. Echinod.’ Monogr. Pal. Soc. p. 276) gives 
merely a verbatim copy of Forbes’s text, and the only original observa- 
tion which he offers is that the anus is in the middle of the obtusely 
subtruncate border. In this heis mistaken, for it occupies the usual 
position towards the top of the posterior truncation. He gives, 
however, an admirable plate of the large form described by Forbes, 
in pl. Ixia, figs. 1, 2a&6. These figures the present writer would 
accept as correctly defining the naked-eye appearances of the test, 
and for this reason no other general figure is given in this paper. 
In Pl. XXXYV, line ui, of this paper, a large example is photographed, 
to show the typical profile of the large form of this species, and to 
serve as a contrast to the much commoner smaller forms which are 
depicted in Jine i, Nos. 1 to 4. 

Like Cotteau, Wright also looked upon JM. cor-bovis as a gigantic 
variety of M. Leskei, but it is reasonable to infer that his acquaint- 
ance with the species was inconsiderable, as he ignored the examples 
of smaller size, and failed to note many important features of the 
test. It may be mentioned also that most authors have had a 
misconception of Forbes’s type, and have generally confounded it 
with MM. Lesket. 

It will, therefore, be evident that considerable difference of 
opinion has existed in the case of this Micraster, and that, for so 


Vol. 55-] DR. A. W. ROWE ON THE GENUS MICRASTER. 519 


important a species, the description is singularly lacking in point. 
The imperfect description is probably the cause of the species being 
so little understood, as the writer has met with no English palzon- 
tologist who could with certainty distinguish a small Micraster 
cor-bovis from a large M. Leskei, and yet they are as easy to 
separate as J. precursor and M. cor-anguinum. 

This form is not common in any of the English sections men- 
tioned in the opening sentence of this paper, and its range is from 
the base of the Zerebratulina gracilis-zone to the top of the Holaster 
planus-zone: one example only has been found in the middle of 
the MM. cor-testudinarium-zone. It is commonest in the gracihs- 
beds, where, save for a few M. Leskei at the top of the zone, it is the 
only Aicraster found, and it ranges through the AH. planus-zone, 
from top to bottom, including the Chalk-rock. The large forms are 
generally obtained at the top of the zone of H. planus, where one 
was obtained measuring 81 mm. in length; but Gen. C. F. Cockburn 
has found the large form well down in the gracilis-beds at Dover, 
where, as a rule, they rarely exceed 50 mm. in length. 

It has been suggested that the large and small forms are two 
distinct varieties—the small form being found chiefly in the 7. gra- 
cilis-zone, and the large at the top of the H. planus-zone ; but 
Gen. Cockburn’s large example from the 7’. gracilis-beds, and the 
fact that the small forms from the H. planus-zone in no way 
differ from those in the zone below, negative this idea. The large 
form is looked upon as a mature stage of the small form, reaching its 
maximum development at the top of the H. planus-zone, and then 
suddenly dying out. On the whole, bulk for bulk, the small forms 
are taller than the large: a by no means remarkable fact, when 
one considers that young forms are generally tumid. 


As Forbes’s description is so meagre, it has been thought 
necessary to give here the results of a detailed examination of a 
number of zonally-collected examples. 

Test.—This is very thin, thus accounting for the rarity of 
perfect examples. Even the large specimen, 81 mm. long, figured 
on the extreme right of line ii, Pl. XXXYV, has a test as thin as 
that of H. planus, and this is, in the writer’s experience, an un- 
varying feature, and one of high specific importance. Though J. cor- 
bovis is a comparatively rare fossil, it is commoner than is generally 
supposed, as many broken examples are mistaken for specimens of 
H. planus when seen in situ, and nothing short of extracting them, 
and cleaning a portion of the test in the field, will suffice to determine 
the difference. No other Micraster, however small, has a test so 
thin, and this feature alone is sufficient to establish a determination. 
This notable character escaped the attention of Forbes, and of other 
keen observers. 

Size.—WM. cor-bovis attains a larger size than any other Micraster 
in the English Chalk; but large forms are comparatively rare. 
They may be readily mistaken for examples of Holaster placenta, Ag., 
when seen in section in the cliff. 


520 DR. A. W. ROWE ON THE GENUS MICRASTER.  {[ Aug. 1899, 

Shape.— Unlike that of any other Micraster. The large forms 
are generally of an elongated ovoid shape; the small are markedly 
wedge-shaped, as a rule. Wright’s figures are particularly good, 
for they bring out the rows of prominences on the lateral aspect ot 
the test, which resemble the bossing on Hemiaster Morrisi. This is 
seen only in large examples. 

Length and breadth.—Itis a very long form, the length being, 
as a rule, proportionately greater than in any other Mvcraster. 
Examples have been measured which are 7 mm. longer than broad, 
and also broad examples; where the difference in favour of the 
length is as little as 2 mm.; but this small difference is unusual, 
and a conspicuous length is the rule. As in all other species and 
varieties, there is a broad form and a narrow form, but the writer 
has never found one with the length and breadth equal. Measure- 
ments of three individuals and the average of small forms are here 
given :— 


Length. Breadth. Height. 
Deven. a 79mm. 73mm. 49mm. _ ZT. gracilis-zone, Dover. 
De ebetceee 81 mm 76mm, .44 mm. 1. planus-zone, Dover. 
oie s aaa 76 mm 65 mm. 45 mm. Forbes’s type. 
Fs OO ei ae 5I mm 47 wm. 31 mm. Average of small forms, Dover. 


Height.—All the specimens of this species that I examined are 
notably depressed. 

Position of apical dise.— This is remarkably anterior, 
giving an average excentricity of no less than 9 mm., or 3 mm. 
more than the average of all the other forms in the zone of 
Holaster planus. No other Micraster shows any approach to this 
anterior excentricity. 

Position of mouth. — Always distant from the anterior 
margin, the average distance, for large and small forms combined, 
being over 9 mm., and that for the small forms alone being just 
under 9mm. In large examples the month looks very small for 
the size of the test. 

Peristome.—this is in the highest degree characteristic, con- 
sisting of a smooth, flat ring, with no trace of the jointing of the 
anterior peristomal plates. It has a striking resemblance to that 
in Hemiaster. (Pl. XXXIX, fig. 1.) 

Labrum.—Always present, but invariably rudimentary. It is 
merely an angular downward-curving thickening of the peristomal 
ring. The whole of the mouth-opening is exposed to view. This 
is also similar to that in Hemiaster. (Pl. XX XIX, fig. 1.) 

Paired ambulacra.—tThese are deep—notably deep when one 
considers the thinness of the test, and very short for the size of 
the test. The posterior pairs are flexuose, contracted at their 
extremities, and much shorter than the anterior, the number of 
pores being 23 to 28 in a medium-sized example. The paired 
pores. differ from those in other forms of Micraster, in that both 
the inner and outer rows are elongated, and the two are 
of almost equal length. In well-preserved examples, the outer 
rows of pores are tear-shaped. So far as the writer knows, no 


Vol. 55.] DR. A. W. ROWE ON THE GENUS MICRASTER. 521 


other Micraster has the outer pores of this shape. On looking at 
Pl. XXXVI, fig. 1, the left-hand rows of pores seem much rounder 
and more crowded. This is not merely an effect of lighting and 
foreshortening, for an examination of all the specimens shows that 
the anterior wall of the ambulacrum in this species is much steeper 
than the posterior, and the pores have thus much less space for 
spreading out. The interporous ridge is either absent or feebly 
developed. 

Single ambulacrum.—This is comparable with the paired 
ambulacra, though, instead of being absolutely smooth, it is orna- 
mented with fine and discrete granules. The only single ambula- 
crum which in any way resembles it is that of WM. Leskev; but in 
the latter the granulation is more abundant and close-set. (Pl. 
XXXVII, fig. 1.) 

Interporiferous area.—This forms the type of the ‘smooth’ 
area. It is devoid of granules, and shows no trace of the suturing 
of the interzonal plates. Owing to its smoothness and lack of cha- 
racter, it is very difficult to photograph. It will be noticed that the 
posterior ambulacra have a great resemblance to those of Hemzaster 
Morrisi, for both are short, curved, contracted at the end, with 
feeble or absent interporous ridge, elongated internal pores, and 
smooth interporiferous area (Pl. XXXVI, fig. 1). 

Anteal sulcus and notch.— Both are very shallow —so 
shallow, indeed, as to be practically absent in some examples. In 
this again the form now described resembles Hemiaster. 

Curve of superior surface.—This falls equally under two 
groups—the fiat-arched and the gibbous. On Pl. XXXYV, line i, 
Nos. 1, 2, 3, & 4, are seen, in their order, the forma Normannie, 
the flat-arched form, the form with the slight carinal rise, and the 
gibbous variety. The writer has been unable to find the round- 
arched or beonensis-form, though there is little doubt that it exists. 

Rostrum and carina.—Rostrum invariably absent, and carina 
never more than rudimentary. 

Sub -anal fasciole.—Oval and very weak—weaker than in any 
other Micraster in the low-zonal.series. 

Plastron.—This is in the last degree characteristic. The rows 
of tubercles are very regular, and owing to the thinness of the test 
they are very sharply cut, and stand out in a-prominent manner. 
This prominence is intensified by the fact that the tubercles rise 
sheer out of a broad, smooth, and flat areola, and that the areolar 
circle is thin, flat, and scattered, made up of a few prominent 
and very discrete granules. This is well seen in Pl. XXXVIII, 
fig. 6, and the contrast between it and that of M. Leska is sharply 
brought out on fig. 2 of the same plate. 

Periplastronal area.—This is a broad, smooth, or very 
faintly granular band, which surrounds the plastron and labral 
plate, and by its smoothness throws up the plastron into still 
greater prominence. This smooth area is constant, and is in 
striking contrast to the strongly granular band which surrounds 
the plastron i in all other forms of Micraster. 


922 DR. A. W. ROWE ON THE GENUS MICRASTER. [Aug. 1899, 


In the case of Micraster Leskei this band is never smooth, and 
the contrast between it and the same area in M. cor-bovis is plainly 
shown in Pl, XXXVIII, fig. 1, and Pl. XXXIX, figs. 2 & 3. 
That the area is really smooth in MM. cor-bovis may be seen in 
Pl. XXXVIII, fig. 6, which shows the junction of the plastron 
and the periplastronal area. To Gen. C. F. Cockburn, who supplied 
Forbes and Wright with so much material, belongs the credit of 
this observation, and the writer agrees with him that this feature is 
diagnostic of the species. 

Primary tubercles on base.—These are similar to those on 
the plastron. At the anterior base they are very scattered, showing 
up strongly on account of the feeble areolar circle, and the absence 
of inter-areolar granulation, and they afford an additional aid in 
making a determination between this species and WM. Lesket. In 
the latter the tubercles are crowded, the areolar circles are thick, 
and the inter-areolar spaces are filled up with strong granulation. 
Compare Pl. XXXVIII, fig. 6 with fig. 2. In large specimens of 
M. cor-bovis the tubercles on plastron and base appear conspicuously 
small. 

Basal plates.—In all large and unworn specimens these form 
a noteworthy feature, as they are set at slightly different angles, 
and their sutures are very prominent. Owing to the varying angle 
of incidence of light, these plates give the base a curiously facetted 
appearance. This feature is found in Holaster and Cardiaster, 
and is merely a question of thinness of test. It is worth noting, 
however, as it is rarely seen in the thick-tested forms of Micraster, 
and is characteristic of the species under discussion. This feature 
is beautifully brought out in Wright’s figure. 

Affinities and differences.—As will have been gathered 
from the foregoing detailed description, this species has not a few 
points in common with Hemiaster Morrisi. Those which it has in 
common are the thin test, shallow sulcus and notch, mouth distant 
from border, similar peristome and labrum, rudimentary tubercu- 
lation of labral plate, smooth ambulacra with contracted ends in 
posterior pair, elongated inner row of ambulacral pores, smooth 
periplastronal area, and lateral bosses. The points of divergence, 
on the other hand, are that in H. Morrisi we find a peripetalous 
fasciole and no sub-anal fasciole, an accentuated carina,a’ vackward- 
sloping posterior truncation, broader ambulacra,; the anterior paired 
ambulacra being equally pointed at the ends with the posterior pair; 
the primary tubercles on the base are set in very narrow saucer- 
shaped areole, with raised edges, and the apical disc is much less 
excentric anteriorly, and sometimes posterior. Though Hemaster 
belongs to a different genus, there are sufficient points in common 
between it and MW. cor-bovis to make the comparison of interest from 
an evolutional standpoint, as the latter shows certain contact-points 
with an earlier form. 

The comparison with M. Leskei is equally instructive, as it marks 
the passage from the thin-tested Terebratulina gracilis-form to the 
thick-tested Holaster planus-form, The points of similarity are the 


Wols 55.| DR. A. W. ROWE ON THE GENUS MICRASTER. 523: 


smooth interporiferous area, with inner ambulacral rows frequently 
elongated, rudimentary interporous ridge, marked anterior excen- 
tricity of disc, very shallow sulcus and notch, mouth distant from 
the border, similar labrum, undivided peristome, rudimentary tuber- 
culation of labral plate, and feeble fasciole. The points of distinction 
are that in Micraster Lesket the size is small, the test thick, the 
areolar circle and inter-areolar granulation round the primary 
tubercles of the base are strong, the periplastronal area granular, and 
the carina frequently moderately developed—all of which features 
are absent in WM. cor-bovis. In addition, the anterior segment of 
the peristome is an undivided raised ring in M. Leskei, whereas it 1s 
flat in WV. cor-bovis. With these points Fae distinction to guide one, 
it will be impossible to confound the two species. 

Variations.—As in every other Muicraster, these are con- 
spicuous, and while the essential features of the test are unalterable, 
there is considerable difference in the less important, and more 
plastic, characters of mere size and shape. The variations in size 
and shape are depicted on Pl. XXXYV, line i, Nos. 1 to 4, and the 
forms shown are the depressed forma Normannie, the flat-arched 
forma planidorsata, the forma carinata, and the forma gibbosa. On 
the extreme right of line ii is included one of the large forms, of 
characteristic shape and dimensions. 

Young state.—The young forms show no deviation in the fixed 
characters of the test, but they are generally more inflated, with 
shallower sulcus and notch, and with shallower ambulacra. The 
relatively small size of the mouth and of the primary tubercles 18 
not so conspicuous as it becomes in the mature state. 

Passage-forms.—This is a point of extreme interest, as it. 
marks the continuity of the evolution of the genus in its more 
primitive forms. From the Holaster planus-zone both Gen. Cockburn 
and the writer have obtained examples of medium size, where the 
test is thin, and the interporiferous area is either ‘ smooth’ or faintly 
‘ sutured,’ and yet where the other fixed features of the test lean 
more towards M. Leskerx. very possible variation between the two 
species may be traced in their passage-forms. For instance, in 
Pl. XX XVIII, fig. 5, is shown an example, in beautiful preservation, 
where the ambulacra are typical of I. cor-bovis, and the peristome 
is also of that type, and yet the granulation of the periplastronal area 
and around the basal tubercles essentially belong to M. Leske, 
though the test is as thin as in a specimen of H, planus. Another 
example has a typical M. Leskei-peristome, and yet the other 
features of the base are characteristic of M. cor-bovis. Here again 
the test is quite thin. These variations could be multiplied, and 
nothing but the exigencies of space prevents me from giving 
photographs of these instructive transitions. 

It should be noted that no other thin-tested Micrasters have 
been found, either in the 7. planus or M. cor-testudinarium-zones, 
which have the ‘inflated’ interporiferous area, and the other 
characters associated with WM. precursor in these zones. This is of 
manifest importance, as it goes far to prove that MV. cor-bovis passes 


524 DR. A. W. ROWE ON THE GENUS MICRASTER.  [ Aug. 1399, 


direct tnto Mcraster Leskei, and into it alone, and that it haS no 
direct zoological association with the other low-zonal forms; these 
Jatter, in turn, being directly derived from M. Leskev. 

Distribution.—At Dover this Micraster has been found 
throughout the upper 90 feet of the Terebratulina gracilis-zone, and 
it probably extends lower still. It occurs from top to bottom of the 
Holaster planus-zone, and then suddenly dies out. A solitary 
example has been discovered 30 feet up in the M. cor-testudinarvum- 
zone. It has not been found in the Rhynchonella Cwvicri-zone, in 
the West Cliffs, but the search has not been so exhaustive there as 
in the Hast Ciiffs. 

At Beachy Head it has been found only in the 7. gracilis and 
H. planus-zones, and then only in small numbers. At Beer Head, in 
South Devon, it is seen throughout the entire extent of the T. gracihs 
and H. planus-zones, and it is quite as abundant as at Dover. 
Examples have been obtained at the base of the 7’. gracilis-zone, a few 
feet above the junction with the beds of Rh. Cuviert. On the Dorset 
coast it was found near the top of the gracilis-beds, and in the 
zone of H. planus. Fragments of a small thin-tested urchin have 
been found in the Rh. Cuviert-zone at Beer, but sufficient material 
has not yet been obtained to allow of a reference of these fragments 
to the genus Meraster. 


A full description of the diagnostic features of this interesting 
Micraster has been given, because the writer has been unable to find 
any account of it which does justice to its strong individuality. No 
Micraster, save M. Sancte-Maure, Gauthier, is so sharply marked 
out from its fellows, and has so strong a claim to be stamped as a 
distinct and definite species. Even the minor points which have been 
brought out are worthy of notice, and no single one is immaterial 
to the formation of a determination. It will be noticed that stress 
has been laid on the importance of the thinness of the test, and it 
will be apparent that many of the salient features, upon which we 
rely for a determination, are also due entirely to this cause. 

_M. cor-bovis has all the low-zonal features, which are so strongly 
exemplified in M. precursor and M. cor-testudinarvum, and that in 
an exaggerated degree ; and, in addition, many of the fixed features 
of the test are rudimentary to a notable extent. It will, therefore, 
be not unreasonable to look upon this primitive form as the pro- 
genitor of M. Leskei, and through it of M. precursor and M. cor- 
testudinarvum. ) 

Owing to the necessarily limited space, and to the excellence of 
the plates of the large forms by Forbes and Wright, it is here 
sufficient to give the profile figures on Pl. XXXYV. Photomicro- 
graphs of the essential characters of the base, upon which one must 
rely for a determination, will be found, however, in Pl. XX XVIII, 
fig. 5, and Pl. XXXIX, figs. 1-4. 


Vol. 55.] DR. A, W. ROWE ON THE GENUS MICRASTER. 525: 


(2) Group of Micraster Leskei. 
M. Leskei, Desm., 1837. 


The figures given by the following authors are accepted as being” 
good representations of the general shape and appearance of the test, 
but for the essential details, which, after all, are the only real guide 
to a species, the reader is referred to Pl. XX XVIII, figs. 1, 2 & 3, 
and to Pl. XXXVI, fig. 2:— 


Corrrav, ‘ Echinides fossiles de l’Yonne,’ pl. lxxvi, figs. 2 & 3. 

Cayrux, ‘Mém. sur Ja Craie grise du Nord de la France,’ Ann. Soc. géol. 
Nord, vol. xvii (1889-90) p. 105 & pl. iii. 

Waieur, ‘ Brit. Cret. Echinod.’ Monogr. Pal. Soe. pl. Ixiia, figs. 3a & 0. 


The name of MW. Leskei has been retained, because that of IW. brew- 
porus, Ag., 1840, is a nomen nudum, and because the Agassiz cast 
(Centuria M, 10) in the British Museum (Natural History), Crom- 
well Road, in no way conforms to what we understand by this. 
species, being apparently merely a young example of WM. cor- 
angunum. 

For a complete synonymy up to 1857 the reader is referred to 
Cotteau’s ‘Echinides fossiles de l'Yonne,’ vol. ii, p. 352, and for 
more recent writings to those of L. Cayeux* and V. Gauthier,” the 
latter of whom has written a very thoughtful paper on the affinities 
and varieties of this species, clearly setting forth the difficulty of 
knowing where to draw the line, in separating the small from the 
large forms, and the large examples from other allied low-zonal types. 
The lack of familiarity on the Continent with J. cor-bovis has still 
further increased the confusion. 

While nobody, who is in any way familiar with the species under 
discussion, would have any difficulty in determining the identity of 
a small and typical example, it is equally clear that, as soon as. 
we pass from the small and typical forms, we meet with a 
number of larger and closely-related forms, which we have 
great difficulty in referring to the type. There is probably no 
species whose exact limitation is fraught with so many difficulties ; 
but it is hoped that, by means of the photomicrographs which illus- 
trate this paper, it can be demonstrated that we have means at our 
disposal for defining the species within more rigid limits, and, by 
tracing the passage-forms, to indicate at what point we must draw 
the line. It will not be necessary to go minutely into all the 
features of the test, as we have done in the case of 1. cor-bovis,. 
but attention will be drawn to certain essential characters, which 
will enable us to separate this species from its passage-forms; for, 
once having eliminated M. cor-bovis from the discussion, we have 
only the passage-forms to deal with. 

Now, in England, at any rate, we look upon WM. Leskei as a small 


i Op. supra cit. 
2 «Deser. des Espéces de la Craie de Reims,’ Bull. Soc, Sci, Nat. de l’Yonne, 
vol. xii (1887) p. 8. 


526 DR. A. W. ROWE ON THE GENUS MICRASTER. [ Aug. 1899, 


Micraster, and those which have been given to the writer from Con- 
tinental sources are also rather small. Cotteau, Roemer, de Loriol, 
Cayeux, and Gauthier, on the other hand, have medium, or even 
large, examples in view in their figures and descriptions, and it 
behoves us to examine their position, and to show where their diffi- 
culties lie. Cotteau, for instance, distinctly defines it as ‘ a species of 
rather large size,’ and he even gives measurements of examples (not 
M. cor-bovis), which are 65 mm. long; while in addition, he figures 
in his ‘ Kchinides fossiles de l’Yonne,’ pl. xxv, fig. 6, a large tumid 
example, which has given rise to much discussion by subsequent 
writers. 

It will be unnecessary to analyse the views of each individual 
writer, as they all more or less fall in with Cotteau’s ideas, in 
referring all these large forms to MW. Leskev, though some of them do 
so with obvious hesitation. The prevalence of the ‘ sutured ’ inter- 
poriferous area in the zone of Holaster planus—a purely horizonal 
feature—and its similarity to the ‘smooth’ area in M. Leskei, have 
probably induced mary writers to refer these large examples to the 
Micraster in question. 

A solution is possible only in a section like that of Dover, where 
the beds are very rich in Micrasters, and where the dip is very 
gentle, thus giving one the chance of working a long cliff-section 
yard by yard. Inthe H. planus-zone at Dover—and the same occurs 
ai Beachy Head, on the Dorset coast, and at Beer Head—we find a 
much larger proportion of small forms than in any other zone, which 
all more or less resemble what one looks upon. as the type of 
M. Leskei; and though mere size is, as a rule, the weakest of all 
evidence to lean upon, we are forced to consider here whether it may 
not have itsmeaning. While it is impossible to deny that this zone 
is peculiarly rich in small forms of Micraster, 1t is equally certain that 
we find an abundance of medium-sized forms, as well as some of the 
largest examples which the English Chalk produces. These last are 
especially common just above the Chalk-rock at Dover. It is, there- 
fore, clear that in this zone Micraster had as good a chance of 
reaching maturity as at any other horizon, and that the small 
M. Leskei-forms cannot be considered as mere immature examples. 
The medium-sized and large forms frequently have an interporiferous 
area, which at the first glance, appears to be smooth, though in 
reality it is clearly ‘ sutured ;’ the labral plate, moreover, is freely 
tuberculated, and the anterior segment of the peristome is plainly 
jointed. These are the forms, found only in the H. planus-zone, 
which constitute a perfect transition between M. Lesket and 
M. precursor. 

The only fair way to establish a difference between the small 
type-form and the larger transition-form is to examine a large 
series of each by means of photomicrography. This has been done, 
and in Pl. XX XVIII, fig. 1, is shown an average-sized and typical 
example of what the writer considers to be M. Lesker; while in 
fig. 3 of the. same plate is depicted the characteristic peristome of this 
species, and in Pl. XXXVI, fig. 2, is seen one of the anterior paired 
ambulacra. By way of contrast, the reader is referred to Pl. XXXVI, 


Wolk 5524 DR. A. W. ROWE ON THE GENUS MICRASTER. 527 


fig. 3, and Pl. XXX VIII, fig. 4, for the ambulacrum and peristome 
of the characteristic passage-form. 

If we can find certain features in these small Micraster Leskev- 
forms, which are not characters of immaturity, and differ from other 
equally small examples of the JZ. precursor-type, in the same zone, 
then we shall have some grounds for defining a scheme of separation, 
which will go far towards establishing J. Leskei on a firm specific 
basis. Now the general characters of M/. Leskei are those which are 
common to all low-zonal forms—namely, depressed and cuneiform 
shape, anterior disc, mouth distant from border, shallow sulcus and 
notch, deep ambulacra, and narrow fasciole. 

The essential features of the species are :— 

Interporiferous area.—Perfectly smooth, like that of 
M. cor-bovis. A fine granulation is seen in the passage-form to 
M. precursor, but never in the true M. Leskeit. The inner row of 
pores are often elongated, like those of JZ. cor-bovis (Pl. XXXVI, 
fig. 2). 

Interporous ridge. —KHither absent or weak. 

Single amb nlacrum. —Much resembling that of VW. cor-bovis, 
but the granulation is obviously closer and more abundant. Occa- 
sionally, in perfectly typical examples, a trace of suturing is seen, 
but the junction of the plates is, as a rule, not indicated. 
(EE XVI, fig. 2.) 

Peristome.—This is in the form of a smooth raised ring, with 
the jointings of the anterior peristomal plates not indicated. Occa- 
sionally, smooth nodular inflations are seen on the anterior segment, 
the constrictions denoting the points at which the jointings would 
appear in other species. This unbroken peristomal ring is found 
only in WM. cor-bovis and M. Leskei; the jointings are a characteristic 
feature of all other Micrasters, and they become more marked as 
one ascends the zones. The typical 1. Lesket-peristome is shown in 
Pl. XX XVIII, fig. 3. 

Labrum.—Always rudimentary and quite smooth. Sometimes 
the smooth tip looks as if it were a separate piece which had been 
stuck on; but this is probably due to secondary deposition of car- 
bonate of lime. 

Labral plate.—Triangular in shape, with the broad base at the 
plastron, and tapering to a point at the labrum. Primary tubercles 
very few and irregular, and no true linear arrangement even in the 
largest examples. There are rarely more than six tubercles on the 
plate, and often only two or three. Pl. XX XVIII, fig. 1, from a 
typical and well-preserved example, has only two—one at the top 
and the other at the bottom of the plate. This rudimentary 
tuberculation recalls M. cor-bovis. 

Size.—After comparing numerous examples, all of which exactly 
correspond in their essential features, though derived from widely- 
distant sections, the writer is forced to conclude that the true 
M. Leskei is a small urchin, averaging about 34 mm. in length, and 
rarely exceeding 40 mm. As soon as one passes outside the 
40 mm.-range, the true WW. Leskec-features begin to merge into those 
of the passage-form between it and the Holaster planus-zone type of 


olga 
seas hes 


528 DR, A. W. ROWE ON THE GENUS MICRASTER.  ([Aug. 1899, 


Micraster precursor, which has the ‘ sutured’ interporiferous area, 
and the peristome with jointed plates. 

Variations.—These are merely confined to shape, and the chief 
variants are shown on Pl. XXXV, line i, Nos. 1’ to 5’, embracing 
the depressed forma Normannie, the flat-arched forma planidorsata, 
the round-arched forma beonensis, the forma carinata, and the forma 
gibbosa. It is unfortunate that these urchins were a little out of 
focus when photographs of them were taken. Though they are 
typical examples of the species, several of them are below the 
average size. 

Young state.—More tumid, with shallower ambulacra and 
ambital notch. 

Rostrum and carina.— Rostrum absent. Considering that 
this is a very low-zonal form, it is curious that so many examples. 
should have a slight but definite degree of carination. This carina- 
tion is greater than in any of the other forms of Mveraster in the 
Holaster planus-zone. It brings to mind the shape of M. Sancte- 
Maure, Gauthier. — | 

Sub-anal fasciole.—Always distinct, even in the smallest 
examples, but decidedly thin. It is seen on Pl. XX XVIII, fig. 1. 

Tubercles of plastron and anterior base.—Shown in 
Pl. XXXVIII, fig. 2, as a contrast to fig. 6 on the same plate, 
which belongs to M. cor-bovis. For a description of the differences 
between these two species, the reader. is referred to the section 
dealing with WM. cor-bovis (p. 522). 

Periplastronal area.—Always finely granular (Pl. XX XVIII, 
fig. 1). See also note on the same area in the description of 
M. cor-bovis (p. 521). | 

Affinities and differences.—Apparently closely allied to 
M. Sanctee-Maure, Gauthier (which is found in the upper part of the 
Inoceramus labiatus-zone, in the Marne), differing from it, however, in 
that the French urchin is much smaller, the peristomal plates strongly 
jointed, the labrum smaller, and the carina more highly developed. 
The distinctions between M. Leskei and M. cor-bovis have been fully 
discussed under the heading of the latter, and those between it and 
its passage-forms will be set forth below. It is unnecessary to 
compare M. Leskei with M. cor-testudinarium, as there are no contact- 
points between the two forms. 


It will simplify matters if, at this point, the features of the 
passage-form are given. 


(8) Passage-form between Micraster Lesket and — 
M. precursor of the Holaster planus-zone. 


The general features of the test are the same as in all low-zonal 
forms. These are set forth in the summary on p. 516. The essential 
features are :— 

Size.— Anything between 35 and 70 mm. in length. 

Interporiferous area.—The ambulacrum is invariably of 


Vol. 55. ] DR. A. W. ROWE ON THE GENUS MICRASTER. 529 


_ the flat-trough shape, and never triangular in section. The inter- 
poriferous area is always strongly ‘sutured,’ as shown in Pl. XXXVI, 
fig. 3. The transition between the perfectly flat ‘sutured’ area 
and the faintly ‘inflated’ area begins in this form. 

Peristome.—tThe raised ring disappears, and becomes quite flat 
and jointed, in the anterior segment, like all other low-zonal forms, 
only the jointing is not so marked (Pl. XX XVIII, fig. 4). 

Labrum.—lIt has always a smooth labral tip, however large the 
example may be, whereas, in the other low-zonal forms, the tip 
becomes invaded by granules, in a certain percentage of cases. 
. Further, the posterior segment of the peristome is always smooth, 
while it is frequently granular in the other low-zonal forms. 

Labral plate.—This is of the same shape as in Micraster Leskea 
and the other Micrasters of the Holaster planus-zone, but the tubercles 
are much more numerous than in the former species, and often form 
a triangular series of marked symmetry, and of considerable extent. 
Further, in M. Leskei, there is always a hiatus between the 
plastronal and labral series of tubercles, whereas, in the passage- 
forms the two sets are not infrequently merged into a continuous 
whole. 

Shape.—The passage-form may assume any shape, in the same 
way that M. precursor of the H. planus-zone does, and those 
figured in Pl. XX XV, line i, give an exact idea of what one may 
expect. Another point of extreme interest is that the broad forms in 
the H. planus-zone, which one may call M. cor-testudinariwm—the 
M. decipiens, Bayle, of Continental writers—frequently have ambu- 
lacra so smooth that they fall within the ‘ sutured’ class, showing 
clearly that this type of ambulacrum is an horizonal and not a 
specific feature. 

Distribution of M. Leskei and its passage-form.—At 
Dover, Beachy Head, on the Dorset coast, and at Beer Head, 
M., Leskei is found in abundance throughout the whole thickness of 
the zone of H. planus, but no example has been obtained from the 
M. cor-testudinarium-zone. In the Terebratulina gracilis-zone at 
Dover it occurs at the top of that zone, but is very rare, and no 
trace of it has been discovered at the same horizon at Beachy Head, 
on the Dorset coast, or at Beer Head. At Beer Head alone, in the zone 
of Rhynchonella Cuvierr, it is found, but is quite rare. The passage- 
form is found in abundance throughout the #. planus-zone, in all 
three sections, but it has never been obtained below or above that 
particular horizon. It will thus be seen that in MJ. Leskei and its 
passage-form we have an unfailing guide for the top of the H. planus- 
zone, and that, by its aid alone, we can always determine in the field 
the zoological junction-line between this zone and that of M. cor- 
testudinarium. Therefore, quite apart from its zoological interest, 
it is of such value to the field-worker that it is worth placing on 
record. 

It may be argued that this separation of allied forms is artificial, 
and that the true M/. Leske:-forms may be looked upon as immature 
examples of the larger transition-forms. Indeed, the writer at first 


Q.J.G.8. No. 219. Qu 


530 DR. A. W. ROWE ON THE GENUS MICRASTER. [Aug. 1899, 


held this view, until he had examined a large series of both types . 
by the aid of the essential features of the test previously mentioned. 
The invariable association of the ringed, unjointed peristome, and 
the scantily tuberculated labral plate, with the smooth, unsutured 
interporiferous area, and the equally constant conjunction of the 
jointed peristome, and the freely tuberculated labral plate, with 
the ‘sutured’ interporiferous area, give the clue to the method of 
separating the Micraster Leskei-type from its transition-form. If 
the rudimentary tuberculation of the labral plate and the unjointed 
peristome are mere attributes of immaturity, we should expect to 
find some evidence of this in its close ally, M. cor-bovis. On the 
contrary, we find that these two features are as prominent in the 
largest examples, as in the smallest, of that species. 

Moreover, even in the smallest examples of the passage-form, 
the tuberculation of the labral plate is always more abundant and 
symmetrical than in M. Leskei of the same size; and in speci- 
mens of M. precursor of the Holaster planus-zone with ‘ inflated ” 
plates, even though. they be no more than 20 mm. long, the tuber- 
culation is always linear and symmetrical. It would, therefore, 
seem that there is ample justification for the separation of M. Leskei 
from its passage-form, other than that of mere convenience in 
classification. 


(4) Group of Micraster precursor. 


M. precursor, 1899." 


Dimensions.—The forms of Micraster included in this group 
are very variable in size, ranging from 26 to 68 mm. in length, and 
averaging about 50 mm. The breadth is generally about 3 mm. 
less than the length. Small forms are decidedly rare. 

~The writer has ventured to establish a group, rather than to 
found a species for a single form, as is the custom, for the simple 
reason that the variations which group themselves around the 
dominant type are so numerous and so closely linked that any other 
course would be contrary to fact; moreover, this plan prevents a 
_ needless multiplication of the so-called species. 


1 [It might have seemed more in accordance with ordinary methods to have 
named this group the Group of Micraster cor-testudinarium, that being the older 
name; but seeing that the forms answering to J. cor-testudinariwm are com- 
paratively rare in this country, and that M/. precursor is yery abundant, I have 
felt impelled to adopt the latter as the more correct and useful name for the 

roup. 

: miaiiee considering that. the narrow forms are found in the zones of 
Rhynchonella Cuviert and Terebratulina gracilis, and that no broad forms are 
found until we get well into the zone of Holaster planus, it is clear that 
zoologically the narrow forms are the older, and that the broad forms are 
derived from them; and lastly, the Goldfuss diagnosis is so definite in its stress 
on the question of breadth that it would be unwise to merge in it forms in 
which lack of breadth is an essential feature.—June 7th, 1899. | 


Yot. 5524 DR. A. W. ROWE ON THE GENUS MICRASTER. 531 


The dominant form—that with the upper surface in the shape of 
a flat arch—is so abundant in the zones of Holaster planus, Micraster 
cor-testudinarium, and in the base of M. cor-anguinum, that it out- 
numbers the other species andvarieties by at least four to one. Its 
profile, which, it is interesting to note, is the same as that of 
M. cor-testudinarium, Goldfuss, is shown in Pl. XXXY, lines ii 
& iv, No.2. Itis of interest to note that the same type can be 
traced even in the high-zonal series, in the upper part of the M. cor- 
anguinum zone, though of course the special features are different ; 
and it may at this stage be pointed out that the broad forms, as 
shown in Pl. XXXYV, lines iu, v, & vii, No. 2, all show much the 
same outline, Mere shape is of small value as a guide 
to species. 

It has become necessary to name and define this group, because 
it has been the custom of some English paleontologists to merge it 
with the M. cor-testudinariwm of Goldfuss, for the reason that it 
has all the characters of that well-known variety, breadth alone 
excepted; and because the latter is merely the broad variety of 
M. precursor in whatever zone it may chance to occur. 

The dominant type, together with its associated variations, is 
named by me MV. precursor, because it is, in actual fact, the low-zonal 
ancestor of the true M. cor-anguinum auctorum, and because an 
unbroken continuity can be traced from the varied forms of this 
group to equally varied forms in the group of M. cor-anguinum. 
It has not been easy to find a name for this group, which would at 
the same time be short and explanatory of the fact that it is from 
this series of forms that MZ. cor-anguinum springs. Nothing could 
be more perfect than the chain of evidence, based on the essential 
features of the test, which takes us up from the comparatively 
primitive forms of the Holaster planus-zone to the advanced forms 
at the top of the MW. cor-anguinum-zone: the continuity of evolution 
is unbroken, and not a link is wanting. © 

Variations.—The dominant type is exemplified in the flat- 
arched forma planidorsata shown in Pl. XXXY, lines ii & iv, 
No. 2; but the group includes the very depressed forma Vor- 
mannie,| No. 1, of the same lines, the round-arched forma 
beonensis,? No. 3, the forma gibbosa, No. 5, the Cayeusi-form,? the 
Bucailli-torm, and others too numerous to mention. 

Several other shapes could be added, but it is felt that undue 
multiplication of mere profile-variations would obscure the issue. 
One important form has been omitted, the forma carinata, which is 
seen in No. 4 of lines ii & iv (Pl. XXXYV), and this is noteworiby, 
as it foreshadows the strong carination of the high-zonal series. 

Some of these variations have a vertical posterior truncation, 
others slope anteriorly, like Bucaille’s figure of MZ. Normannie ; and 
a few others, again, have a moderate posterior slope, after the 
manner of MM. Michelint, Agassiz. Save in the case of true examples 

4 Bucaille, Bull. Soc. géol. Norm. vol. vii (1883) p. 29 & pl. vi. 

2 Gauthier, Bull. Soc. Sci. Nat. de ’Yonne, vol. xli (1887) p. 373, pls. v & vi. 

3 Parent, Ann. Soc. géol. Nord, vol. xx (1892) pls. i & ii, Ae 

M 


532 DR, A. W. ROWE ON THE GENUS MicrasTeR. ([Aug. 1899, 


of the last-named species, the slope of the posterior truncation 18 
of no value as an index of species. Micraster Michelini has not 
been found in the English Chalk. 

Here, then, we have, from the base of the Holaster planus-zone to 
the top of the lower third of the M/. cor-anguinum-zone (the low-zonal 
series of this paper), a collection of associated forms which vary 
largely within certain definite limits, though in each zone we can 
plainly trace the radiation from the several prominent variants just 
mentioned. Whatever variation in shape M. precursor may assume 
in the zones of H. planus, M. cor-testudinarium, and the base of 
M. cor-anguinum, the general low-zonal features of the test are 
shared by it in common with the other species and varieties in 
these zones. The low-zonal features are enunciated on p. 516. It 
is only the special features of the test that vary from zone to zone. 

So much, then, for the family resemblance, which is so marked 
and continuous that the only way to handle the series is to form 
them into a group, in which are contained the several persistent 
and accentuated variations. But, in spite of this family resem- 
blance, we can in the field allocate each one at a glance to its own 
zone; for so powerful have been the conditions of existence that every 
variation, however marked, is impressed with characters special to 
the zone in which it is found. A more striking tribute to the 
value of zonal geology it would be impossible to conceive. 

The practical outcome of this postulate of fixed essential fea- 
tures of the test for each zone is that we must either make 
these prominent profile-variations of the M. precursor-group do duty 
in each of the zones in which they may occur, or we must face 
the reductio ad absurdum of giving to each form a new specific name 
for each zone in which it may be found. 

Take the forma Mormanme by way of example (Pl. XXXYV, 
lines ii & iv, No.1). As writers have described these variations on 
the basis of shape alone, and ignore the essential zonal features, it 
follows that we must retain this idea of well-known profile-forms, 
and weave them into the scheme of zonal and zoological continuity. 
This particular profile-form is found in the zones of H. planus, 
M. cor-testudinarium, and in the base of the zone of M. cor-anguinum, 
and that in an abundance second only to the dominant flat-arched 
form. ‘To all outward appearance this type is the same in each zone, 
and it is only when we come to examine the essential features of 
the test that we learn that the form varies in its details 
according to the zone in which it exists. 

When we realize that this same profile-form is found in M. cor-bovis 
and M. Leske, that it extends even to the high-zonal MM. cor- 
anguinum, and that it is not confined only to these narrow forms, 
but embraces the broad forms in each zone—then we see of how 
little value is mere shape in forming a species. Surely it is more 
reasonable to recognize that there is a forma Normannie of this 
group, occurring in the zones quoted, and varying zone by zone in 
essential features, rather than to dub it by a different specific name 
for each horizon at which it occurs. 


Volk 55:1 DR. A. W. ROWE ON THE GENUS MICRASTER, 533 


The special features of the test in this group may be enumerated 
as follows :— 

Labral plate.—In the Holuster planus-zone it is triangular, 
with the broad base at the plastron, and tapering to a point at the 
labrum (Pl. XX XVII, fig. 8); in the Micraster cor-testudinarvum-zone 
the base of the triangles becomes notably narrower, and the point 
less tapering’ (fig. 7); in the base of the M. cor-anguinum-zone 
it becomes narrower still, and tends to expand at the labrum 
(fig. 6); in the upper part of the M. cor-anguinum-zone the plate 
is invariably compressed within two close parallel lines, which 
notably expand at the labrum, and the rows of tubercles, instead 
of forming a triangular series, assume a linear arrangement 

fig. 9). 

Labral tip and peristome.—In the H. planus-zone the 
passage-form from M. Leskec to M. precursor has the whole posterior 
segment of the peristome smooth, and the other precursor-forms 
have only the labral tip smooth; in the M. cor-testudinarium-zone 
the labral tip is smooth in 80 per cent. ; in the base of the MW. cor- 
anguinum-zone it is frequently granular; while in the upper part 
of the last zone (in the case of M. cor-angumum auctorum) it is 
invariably granular, even on the under surface of the labrum. 

Interporiferous area.—As a rapid aid to determination in 
the field this is useful in the last degree, and even when the base 
of the specimen is broken, one can tell the zone from which it is 
derived at a glance. It is ‘sutured’ (never smooth) and feebly 
‘inflated’ in the H. planus-zone; strongly ‘inflated’ or ‘ sub- 
divided’ in the M. cor-testudinarium-zone; and ‘subdivided,’ or 
more generally ‘ divided,’ in the top of the M. cor-anguinum-zone. 

Shape of ambulacral groove.—The transverse section is 
that of a rounded trough in the H. planus-zone ; in the M. cor- 
testudinartum-zone, that of a deep triangular excavation; in the 
base of the M. cor-anguinum-zone the triangular excavation is 
becoming shallower; and in the upper part of the last zone (high- 
zonal) it shallows to the extent of being almost flush with the test 
in many examples. See the transverse sections in Pl. XXXVI. 

Periplastronal area,—A progressive degree of granulation is 
observed throughout the low zones, culminating in the mammillated 
prominences in the high-zonal forms, at the top of the M. cor- 
anguinum-zone. (Pl. XXXVII, figs. 6-9.) 

Young state.—Somewhat tumid, but not always. Ambulacra 
and notch shallower. 

Affinities and differences.—The associations with M. Lesket 
have been set forth in the description of the passage-form from that 
species into the M. precursor of the H. planus-zone. With 
M. cor-testudinarium, as regards its special features of the test, 


1 Many Micrastersinthe M, cor-testudinarwum-zone nave a triangular labral 
plate. While the two forms of plate are found in this zone, the narrow form is 
never found in the H. planus-zone, and therefore, where it is doubtful in 
which of the two zones a specimen occurred, the narrow plate would definitely 
exclude the latter zone. ’ 


534 DR. A. W. ROWE ON THE GENUS MICRASTER. [Aug. 1899, 


and according to the zone in which it occurs, it 1s completely in 
accord, while it differs from it only in being less broad, and in not 
reaching so large a size; for, just as the special features of the 
Micraster precursor-test vary in the different zones, so do those of 
its broad form differ according to their horizon. Compare the 
profiles of broad and narrow forms in Pl. XXXY. 

Passage-forms.—the transition between the gibbous variety 
of M. precursor and Epiaster gibbus begins to be foreshadowed in 
the low zones, especially in the WM. cor-testudinarium-zone and in the 
base of the M. cor-anguinum-zone. In the same way, the contact 
between the other salient MW. precursor-type and the equally varied 
and prominent M. cor-anguinum types may be traced in Pl. XXXV. 

Distribution.—Throughout the whole of the zones of Holaster 
planus, M. cor-testudinarwum, and the base of M. cor-anguinum. 
As regards locality, wherever the writer has worked these zones, 
there has he found the salient forms already enumerated. 

No set figure has been given of M. precursor, because it is 80 
plastic a form that nothing but a large series of plates would 
portray it. Moreover, reference has been given to the Continental 
forms quoted, and we simply have to recognize that the group has 
all the low-zonal features enumerated on p. 516, and all the special 
features depicted in Pls. XXXVI & XXXVII. It will be found 
that most of the salient variations in shape are indicated in the 
profile-series of Pl. XXXYV. 


(5) Sub-group of Micraster cor-testudinarium, 
Goldfuss, 1826. 


Length, Breadth. Height. 
ae oa saith aa size. eae 66 mm.+ 68 mm. 47 mm. 
Medium size... 51mm. 52 mm. 33 mm, 


This prominent variety of the narrower M. precursor-form was 
described and figured by Goldfuss in his ‘ Petrefacta’in 1826; and 
the diagnosis which he gives is as follows :—breadth equal to 
length (forma oblonga), or breadth exceeding length (forma lata), 
deep ambulacra, shallow anteal suleus, mouth distant from the 
border, and central apical disc. His excellent figures show a large 
specimen, in which the upper surface is in the form of a fiat arch. 
One accepts the description and figures given in the ‘ Petrefacta,’ 
as admirably explanatory of the general features of the test. The 
only exception that can be taken to Goldfuss’s brief diagnosis is 
that the disc is not central, but is invariably anterior. Goldfuss’s 
type was found in the WM. cor-testudinarium-zone at Quedlinburg. 

M. Lambert tells the writer that this form is special to Germany, 
and that itis not found in France; that what is generally considered 
as M. cor-testudinarium, Goldfuss, is in reality M. decipiens, 


1 The largest specimen measured 73 mm. in length by 74 mm. in breadth. 
This was from the M. cor-testudinariwm-zone, Dover. 


Vol. 55.] DR. A. W. ROWE ON THE GENUS MICRASTER. 535 


Bayle ; and that in the true Goldfussian type the pores of the single 
ambulacrum are unequal, while they are rounded in WMicraster 
decipiens. In this paper it has been decided, however, to retain 
the name of MV. cor-testudinarium for the broad low-zonal varieties 
of the English Chalk. 

This broad variety shares the general features common to it and 
all the low-zonal forms, a summary of which will be found on p. 516. 
Just as I. precursor has special features, according to the zone in 
which it occurs, so does M. cor-testudinarium vary in identical 
degree. Save only breadth and size, it has no general or special 
features that set it apart from the narrow-shaped M, precursor- 
group. It is merely a broad and large low-zonal form. When it 
is noted that all broad forms, whether they be high-zonal or low- 
zonal, have a tendency to assume a large size, it will be clear how 
little claim mere breadth and size have in constituting a specific 
distinction. 

Special features of the test.—There are no features 
special to this variety, but only features which are distinctive of 
the horizon at which it exists. In this matter it is on all fours 
with M. precursor, and, to avoid repetition, the reader is referred 
to the description of the features of that group on p. 533. It is 
just as easy to refer MW. cor-testudinarium to its zone as it is in the 
case of the narrow forms, for its zonal distinetions are identical. 
These facts alone should suffice to establish it as merely a broad 
variety of WM. precursor. 

Variation in shape.—tThe profiles are the same as we find in 
all low-zonal forms, and one must again refer to Pl. XX XV, lines iii 
& v, where it will be seen that the broad forms in each zone are, 
in their profiles, merely the echo of the narrow forms in the same 
zone. As far as mere shape is concerned, it will be seen, on line 
vil, that even in the high-zonal series much the same general out- 
line can be traced, with the addition of certain features peculiar to 
the horizon. Examples coinciding with MW. Gosseleti, Cayeux, 
M., decipiens, Bayle, and M. turonensis, Bayle, should, in the writer’s 
opinion, be grouped under the heading of MM. cor-testudinarium, as 
they appear to be merely prominent variations and not specific 
types. The first is from the MW. cor-testudinaritum-zone, but the 
last two have no zone given in Bayle’s plate. Any one of them 
could be referred with equal truth to either the zones of Holaster 
planus or M. cor-testudinarium, and the last two (AZ. decipiens and 
M. turonensis) certainly extend as far up as the base of the I. cor- 
anguinum-zone. It may be mentioned that all the gibbous forms 
figured in Pl. XXXV have well-developed fascioles. Just as in 
the narrow lM. precursor-group, we have in the broad forms a 
parallel series of profile-shapes—the very depressed forma Nor- 
mannie, the flat-arched forma planidorsuta (the true Goldfussian 
type), the forma beonensis, the forma carinata, and the forma 
gibbosa. There is one gibbous form, however, needing special 
mention, which is figured by Wright in ‘ Brit. Cret. Echinod.’ 
Monogr. Pal. Soc. pp. 335-338 & pl. lxxvi, fig. 1 a—c. This is the tall 


536 DR. A. W. ROWE ON THE GENUS MICRASTER. [ Aug. 1899, 


Hanoverian form, resembling Epiaster gibbus in shape, but possessing 
a well-marked fasciole. Having failed to obtain an example of this 
variety, it is impossible for me to discuss it. I can only say that, while 
the low-zonal gibbous forms reach their maximum elevation in the 
broad and narrow examples from the Micraster cor-testudinarvwum- 
zone, | have never seen any English specimen so tall and gibbous 
as that figured by Wright, save in the high-zonal series. In this 
sub-group, the dominant profile-shape is that with the flat-arched 
upper surface (the Goldfussian type), just as it is in the group of 
M. precursor. 

Distribution.—This variety is not often found in the base of 
the Holaster planus-zone, but it is of moderately frequent occurrence 
in the rest of that zone, including the Chalk-rock, when that bed 
exists. It is found throughout the zone of M. cor-testudinarium, 
and in the base of the zone of M. cor-anguinum; but after that 
point it rapidly ceases to be the M. cor-testudinarium of Goldfuss, 
and it becomes merely the var. latior of M. cor-anguinwm auctorum 
of the high zones. At Dover it is just as frequently found in the 
H, planus-zone as in its own zone, and in this section the largest 
examples of all were collected immediately above the Chalk-rock. 
At Beachy Head, Beer Head, and on the Dorset coast, the pro- 
portion of broad forms in the H. planus-zone is not so large as 
at Dover. The last-named locality, however, must stand as our 
criterion, as no other section affords such opportunities for working 
this zone, nor is any other so rich in Micraster. 

Allusion will be made in the next group to the limit-line of this 
variety, which is fixed at the top of the lower third of the 
M. cor-anguinum-zone, when it will be seen that no merely arbitrary 
division-line has been made between M. cor-testudinarium and M. cor- 
anguinum var. latior, but that the separation 1s warranted by fact. 

It is not a common form in the low-zonal series, aud probably 
20 per cent. would represent the frequency of its occurrence in the 
H. planus- and M. cor-testudinarium-zones. In the base of the 
M. cor-anguinum-zone the percentage is a little higher.’ 

The purist may object to this massing of the varieties of the 
broad series, and say that as Goldfuss gives a figure of a moderately 
elevated, flat-arched form, such as that shown in Pl. XXXV, line vy, 
fig. 2, the title of M. cor-testudinarrum should be restricted to this. 
The only answer to such an objection is that every low-zonal 
species or variety has its definite scale of shape-variations, whether 
it be broad or narrow, and that it is impossible to create a special 
restriction in favour of one variant, as it at once breaks into the 
scheme of zoological continuity, which M:craster so well exemplifies. 
The figure quoted is slightly flatter than the Goldfuss type, but it 
would be easy to replace it by one of somewhat greater elevation. 

Affinities and differences.—Its complete accord with 


[! Since writing the above I have visited the Dorset coast, and in one locality 
there noted the unusual occurrence of a M. cor-testudinariwm-zcne where the 
broad forms predominated in numbers. ‘This was only in one spot, for in other 
exposures in the same zone the usual preponderance of narrow forms was the 
rule.—June 7th, 1899.] 


Vol55.1 DR. A. W. ROWE ON THE GENUS MICRASTER. 537 


Micraster precursor, according to the zone in which it occurs, has 
already been made clear. The writer has not seen the type of 
M. intermedius, Bucaille,' but the description and figure of this urchin 
make it appear that it is merely a broad form, with a curved slope 
from apex to anus, derived from the lower half of the zone of 
M. cor-anguinum. Its mouth placed far from the margin, and its 
rudimentary labrum, give colour to this view. It is not a true 
low-zonal form, but, as its name implies, an intermediate stage 
between the broad low-zonal and the broad high-zonal series. Its 
well-marked fasciole, and its superior surface with a curved fall 
from apex to anus, take it out of the Hpiaster-series. This same 
curved fall from apex to anus is not infrequently seen in the high- 
zonal Gravesend urchins, both narrow and broad, but in them the 
mouth is generally nearer the border, and the labrum more developed. 
The relationship to M. decipiens, Bayle, M. turonensis, Bayle, and 
M. Gosselett, Cayeux, has already been noted. 

Passage-forms.—The passage-form which is of chief interest 
is that which occurs in the middle of the M. cor-anguinum-zone, 
where, like M. precursor, it begins to take on high-zonal attri- 
butes, foreshadowing the full high-zonal development. At this 
point the horizonal influences become so strong that it ceases to be 
M. cor-testudinartum, and becomes merely the var. latior of the 
true M. cor-anguinum auctorum. 

So far as breadth is concerned, there are passage-forms from 
M. precursor to its broad variety, and this occurs in every zone in 
which M. precursor is found, and in every profile-form in which it 
exists. In fact, there are many forms of Micraster where the eye 
is unable to decide whether they must be placed in the broad or 
the narrow series, and the millimetric gauge has to settle the point. 
It is splitting hairs indeed when a measurement of 1 or 2 milli- 
metres has to decide the question of a Micraster having one or other 
specific name. This alone, without taking into consideration the 
fact that the special features of the test are the same in broad 
and narrow forms, is sufficient to make one very shy of adopting 
M. cor-testudinarium as a well-defined species. 

It seems to be beyond doubt that in each zone, and in each species 
and variety, there are broad and narrow forms; and it appears to 
be equally clear that the percentage of broad forms increases as we 
ascend the zones. Below the Holaster planus-zone there are no forms 
where breadth and length are exactly equal, but many examples 
run it very close. It is merely because length is the preponderating 
factor that we do not have the so-called M. cor-testudinarium in the 
Terebratulina gracilis-zone. | 

Young state.—There is nothing special about this stage, save 
that the ambulacra are generally shallower and the test more 
tumid. 

It has been stated that examples of the sub-group M. cor-testudi- 
narium in no way differ from those of the group of M. precursor, 


2 Bucaille, Bull. Soc. géol. Norm. vol. viii (1883) p. 31. 


538 DR. A. W. ROWE ON THE GENUS MICRASTER.  [Aug. 1899, 


so far as the special features of the test are concerned. Owing to 
their greater bulk and breadth, however, there are certain small 
differences between them, but they are purely the outcome of in- 
creased size and breadth. For instance, the labrum and labral 
plate are broader, and the periplastronal area more developed, in 
the former; also the sutures of the periplastronal plates are very 
marked, giving a lyre-shaped arrangement of grooves, which is 
sometimes very prominent. 


(6) Group of Micraster cor-anguinum auctorum. 
M. cor-anguinum (Leske) 1778." 


Excellent figures of the general appearance of the test may be seen 
in Wright’s ‘ Brit. Cret. Echinod.’ Monogr. Pal. Soc., pl. lxu, and in 
Forbes’s Dec. Geol. Surv. ii, pl. x. It is not proposed to review 
minutely this group 1n the present paper, but for the sake of necessary 
comparison the high-zonal features are tabulated and contrasted 
with the low-zonal characters on p. 516. In addition a series of 
profile-forms are shown in Pl. XXXYV, line vi; the paired ambulacra 
are figured in Pl. XXXVI, figs. 7 & 8; the single ambulacrum in 
Pl. XX XVII, fig. 5; and the features of the base are brought out 
in Pl, XXXVII, fig. 9. Only examples from the upper two-thirds 
of the WM. cor-anguinum-zone have been considered in this section, as 
the lower-third of the zone has been referred to under the heading 
of M. precursor. 

The type-form of this group is figured in Pl. XXXYV, line vi, 
fig. 5, and it is, of course, the forma carinata of the higt-zonal 
series, which has been worked up to as a maximum of carnal 
development through all the carinated forms in the low-zonal 
M. precursor-group, as shown in lines 11 & iv, No.4. The a. tual 
maximum of carinal development is seen in M. rostratus, Mantell, 
which was figured from the Brighton Chalk. The present writer 
has met with this particular form only in the zone of Marsupites 
testudinarius. This high-zonal carinated form is the type ot the 
high-zonal series, just as the forma planidorsata of the M. precursor- 
group is the type of the low-zonal series. Allowing for the difference 
of horizon, with the necessary evolution of special features of the 
test, the profile-shapes in the high-zonal series are the counterpart 
of those in the low-zonal series, for we have forms resembling the 
very depressed forma Normannie, the flat-arched forma plani- 
dorsata, the round-arched forma beonensis, the forma carinata, and 
the forma gibbosa. M. cor-anguinum is every whit as prone to 
profile-variation as its low-zonal ancestor M. precursor. 

It will be unnecessary again to allude in detail to the photo- 
micrographs of the special features of the test, as they have 
already been commented on, by way of contrast, in the section 
on the special features of the test, and in the Tabular Summary 
on pp. 512-513. | 


1 Leske, ‘ Addit. ad Kleinii Disp. Echin.’ 1778, p. 221. 


Vol. 55.] DR. A. W. ROWE ON THE GENUS MICRASTER. 539 


(7) Sub-group of Micraster cor-anguinum auctorum, 
var. latior. 


This, the broad series of Leske’s type, has been included in the 
present paper, because the zoological scheme would be incomplete 
without it, and it has just as much title to notice as the broad series 
of the low zones. Indeed, if numerical proportion have any value, 
it has a stronger claim, for out of 500 well-preserved and well-grown 
examples from the upper part of the MW. cor-anguinum-zone, no less 
than 50 per cent. were as broad as long, or broader than long, and 
this in spite of the increased rostration and carination due to their 
horizon. 

The broad forms of the high-zonal series have quite as many 
profile-variations as the narrow series, as will be seen on glancing 
at Pl. XX XV, line vii, where we find shapes recalling those in the 
line below—the very depressed forma Normunnic, the flat-arched 
forma planidorsata, the round-arched forma beonensis, the forma 
carinata, and the forma gibbosa. 

The general characters of the test are the same as those given 
for Leske’s type on p. 538; and the only way in which they differ from 
it, apart from breadth, is that they, being broad forms, tend to become 
large, and that a certain number of them exhibit a tendency to be 
flat, to have a shallow notch, deeper ambulacra, and a mouth more 
distant from the border. It is nothing more than a tendency, and 
these features are absent in not a few broad examples of very large 
size. 

This tendency is merely the outcome of the rule that most broad 
forms assume these features up to the top of the M. cor-anguinum- 
zone, but above that level they conform more rigidly to the high- 
zonal type. It has been mentioned before that, in spite of this 
tendency, so powerful was the influence of life-conditions at this 
horizon that the broad forms at this level are often elevated, strongly 
keeled, have shallow ambulacra, a deep notch, and a mouth close 
. to the border. It would seem as if the broad forms tried to pre- 
serve their low-zonal Goldfussian features, but that the conditions 
of life swamped them. In a word, while we have an echo of 
M. cor-testudinarium, Goldfuss, we have at the same time a fore- 
shadowing of the well-known broad form of the Belemnitella-Chalk. 
Allusion is made, of course, to JM. gluphus, Schliiter, which is a 
very large, broad, flat form, with angular ambitus, very deep notch, 
very anterior mouth, and projecting labrum—the culmination of all 
high-zonal attributes. 

In the M. cor-anguinum-zone we find examples which almost tally 
with this last description, but not entirely; just as we find specimens 
which resemble M/. cor-testudinarvwm in some features, but which 
fail to coincide with it in others. The angulation of the ambitus is 
decidedly a high-zonal feature, but it is largely a condition of full 
siZe. 

This sub-group has been styled the var. latior, because that name 
exactly illustrates the point which it is desired to bring out— 


540 DR. A, W. ROWE ON THE GENUS MICRASTER.  [ Aug. 1899, 


that it is merely the broad variety of Micraster cor-anguinum 
auctorum, just as WM. cor-testudinarium is but the broad variety of 
M. precursor. 

These broad forms have no special features of the test which are 
not shared by the narrow type. The paired ambulacra are shown 
in Pl. XXXVI, figs. 7 & 8; the single ambulacrum in Pl. XXXVII, 
fig. 5; and the features of the base in Pl. XX XVII, fig. 9. 

It is needless to give a special figure of this variety, because, save 
only in breadth, it is the same in profile-variations as M. cor- 
anguinum, Pl, XX XY, lines vi & vil. 


Length. Breadth. Height. 
: : Juarge size ~...... 68 mm. 68 mm. 47 mn). 
Dimensions { rom size... 4/ mm, 50 mm. 30 mm. 


VY. ConcLusions. 


The object of this paper is to show that from the beginning of the 
low-zonal series to the beginning of the high-zonal series—from the 
zone of Rhynchonella Cuvierr to the upper part of the zone of M. cor- 
anguinum—we can trace an unbroken continuity in the evolution of 
Micraster ; so that as we mount up, zone by zone, fresh features are 
added to the test, simply owing to the progressive elaboration of 
the epistroma; and that in each zone the special features of the 
test are so marked that one can tell by their aid from what zone 
a Micraster 1s derived. 

In this particular connexion it is necessary to say that, with 
the exception of a few details of measurement, the work of 
Dr. Charles Barrois, on the Chalk of the South and South-east 
coasts of England, stands this severe test of zoological evolution, 
and it is a privilege to record here the value of his zones, and the 
delight which it has been to verify the general conclusions arrived at 
in the invaluable monograph contributed by him to British Geology. 
A paper is already in hand which will give in detail a description of 


the zones of the Chalk, as seen in the cliff-sections of Kent, Sussex, © 


Dorset, and Devon, in order that in future zonal collecting may be 
more easily accomplished. 

It has been thought well to separate the genus into two main 
zoological divisions—the high-zonal and the low-zonal; and it is 
found that the zoological break takes place at about the top of the 
lower third of the zone of M. cor-anguinum. There are, however, 
two great points of departure in the life-history of the genus—one, 
just mentioned, where the low-zonal features begin to be replaced 
by the high-zonal; and the other in the Holaster planus-zone, where 
the thin-tested MM. cor-bovis passes into the thick-tested M. Leske, 
which again merges into the passage-form between it and M. pre- 
cursor, the latter breaking up into typical M. precursor and M. cor- 
testudinarvum, 

The writer has felt impelled to take up a firm position on the 
species question, for if ever an extinct genus gave scope for the 
endless multiplication of specific types, that genus is Mocraster. 


pb a= 


Wole 55:1 DR. A. W. ROWE ON THE GENUS MICRASTER. 5AL 


This position is not assumed in a carping spirit, or on theoretical 
grounds, but it is the outcome of personal and rigid zonal collecting, 
and of the critical examination of a large series of specimens as soon 
as they are removed from the cliff or quarry. 

We must either make a species out of every trivial variation, or 
mass certain obviously allied forms into groups. The latter plan 
seems singularly well adapted to the genus in question, as it gives 
us an opportunity of handling a prolific and variable series, such as 
that of M. precursor, in a broad and effective manner. It is 
only by this means that passage-forms and mutations can be 
intelligibly arranged ; and as they form the bulk of the genus, it 
seems unnecessary to offer further excuse for the course adopted. 
Unless we unite these variations into a group which will admit 
of the zoological continuity being exemplified, and the zonal 
peculiarities noted, we must make a species for each variation, and 
that in each zone. ‘The one plan is sufficient for all purposes of 
nomenclature, and at the same time it marks the evolution of the 
genus, zone by zone; the other is mere ticketing, and meaningless 
ticketing to boot! Judged by this standard, it would seem impossible 
to take a Micraster from a chalk-pit, and to give it a new specific 
name, simply because the curve of the superior surface, or the avgle 
of posterior truncation, differed slightly, or even considerably, from 
figures already published. If the essential features of the test mean 
anything, it would only be possible to found anew species when 
the Micraster differed in its essential features from all other forms in 
that particular zone. This is the logical outcome of such an inquiry 
as this, and by it the writer is prepared to stand. 

Great care has been exercised in classifying the essential details 
of the test in their relationship to the various zones, and the writer 
believes that these anatomical details are substantially accurate, and 
free from speculative taint ; moreover, the collecting has been ex- 
tended over a wide area, so as to avoid local peculiarities. Even if 
the deductions made in this paper may be proved to be invalid, it 
is reasonable to think that the method of examining a genus, by 
taking a large series of zonally-collected specimens in review, might 
with advantage be followed in the case of other genera, and in 
other formations. It would tend to bring out the working of 
evolution, and to reduce the multiplication of so-called species. 

Though it is quite possible that a Micraster may be picked out 
which may not have all the essential features herein demanded for 
the establishing of a zonal determination, at the same time it is 
urged that the conclusions advanced are the result of the examina- 
tion of many hundreds of zonally-collected examples, and that they 
do give a fair average reading of the special zonal characters. With 
so Protean a genus as this, there can be no hard-and-fast rules, and 
there may be trivial exceptions, which in no way weaken the general 
conclusions. ‘ake an instance from the interporiferous area, for 
example: so gentle is the transition from one form to another, 
that in the same specimen we may sometimes see two types of 
areas—three ambulacra being ‘divided,’ and one ‘subdivided,’ and 
soon. But, after all, this is how Nature works, 


542 DR. A. W. ROWE ON THE GENUS MICRASTER.  [ Aug. 1899, 


The distribution of species and varieties may be diagrammatically 
represented thus :— 


a MM COP=ONGUINUM yorccces-) Tair uve M. cor-anguinum yar. latior. Wie ot 
M. cor-anguinum. 
ee ee ee | ms, aE eee eee ee ee eee ee ee 
WAS URCUTRSOR nocecceec  —_ |lgoeane M. cor-testudinarium. Lower third of this 
zone, 
‘apeaiete oie Nee glad eee M. cor-testudinarium. 
M. precursor gonih 
MM. cor-testudinarium 
| ae ee EE ES 
IM, cor-testudinarium...\.....00+ 
Low-ZonaL MM. precursor .....00000-s 
SERIES. 


a MM, cor-bovis. Zone of Holaster 
Die IBGE Sepneconeaa one planus. 


MM. Leskei ......... 


Zone of Terebratulin 
gracilis, 


ctials MM. cor-bovis. 


Note.—The above diagram does not show, as it should do, that M. Leskei occurs 
in the zone of Rkynchonella Cuvieri, but allusion is made to the fact on the 
following page. 


Vol. 55. | DR. A. W. ROWE ON THE GENUS MICRASTER. 543 


This diagram needs a word of explanation, as it is impossible to 
put in‘ an alternative line of descent without running the risk of 
confusion. It merely lays claim to be a diagrammatic statement 
of what obtains in nearly every English section. 

All personal work in the field, and all the information collected 
from other English sources, clearly point to MW. cor-bovis as the only 
Micraster found below the level of the zone of Holaster planus. The 
sole exceptions are the rare occurrence of M. Leskei in the zone 
of Rhynchonella Cuviert at Beer in South Devon, and one solitary 
example found 20 feet down in the Terebratulina gracilis-zone at 
Dover. It is a curious fact that not a single fragment of M. Leskez 
was found in the 7’. gracilis-zone at Beer, though minute search 
was made for it, while MW. cor-bovis was present in considerable 
abundance. This gap in the continuity of a species is remarkable, 
for it comes in with a rush as soon as we enter the H. planus- 
zone. ‘Through the courtesy of Mr. C. J. A. Meyer, the writer 
has been able to examine several Micrasters from the Beer district, 
and he has no hesitation in referring them to M. Leskei, and not 
to M. cor-bovis, as had been done by Mr. Meyer. Therefore, we 
may look upon the appearance of M. cor-bovis in the 7’. gracilis- 
beds, and of MM. Lesket in the zone of H. planus, as the normal 
condition in England, so that the diagram is substantially accurate in 
this particular. The other lines of descent are purely an expression 
of the personal opinion of the writer, and the reasons for such con- 
clusions will be found in the text. The unique appearance of 
M. Leskei in the Rh. Cuvieri-zone at Beer Head finds its parallel in 
the occurrence of the same species above the beds of Cidaris hirudo, 
in the Yonne, where, according to M. Lambert, it is very rare. 
According to the same authority, WM. Leskei is much commoner in 
the zone of 7’. gracilis in France than it is in England. The writer 
has been unable to consult M. Lambert’s monograph on the genus 
Micraster, as he failed to obtain a copy, and he is the more grateful 
to the author for information contained in letters. 

Until within the last few weeks the writer believed that he was 
alone in his views as to the evolution of this genus, but a. little 
tract by Mr. Meyer, on Micrasters in the English Chalk (Geol. Mag. 
1878, pp. 115-117), sent to him by the author, makes it clear that 
Mr. Meyer had already conceived similar ideas, though they were 
never elaborated. Curiously enough, it was the Dover section, with 
its vast zonal range and gentle dip of beds, coupled with its profusion 
of Micrasters, which inspired us both with the same suggestive facts. 


A word of excuse may be offered for the illustrations of this 
paper, as they are the productions of an amateur in an almost un- 
trodden field. The photomicrography of opaque objects is in its 
infancy, the difficulties of technique are almost insuperable in some 
instances, and the whole of the apparatus for taking these plates 
has had to be specially devised. There are limitations to the powers 
of a tens, and it is impossible to make it sharply record detail which 
lies on,widely separated horizontal planes—such as the labral plate 


544 DR. A. W. ROWE ON THE GENUS MICRASTER. [Aug. 1899, 


and. the anterior segment of the peristome. ‘The chief difficulty, 
however, has been experienced with the ambulacra, for it seems 
well-nigh impossible to obtain at the same time the detail of the 
ornamentation and the suggestion of the depth of the ambulacral 
groove. I have had, therefore, to abandon the latter in favour of the 
former, which is all-important, and to be content to demonstrate the 
latter with horizontal sections, as shown in Pl. XXXVI. Whatever 
their imperfections as photomicrographs may be, they give a more 
faithful representation of the features of the test than any drawing 
could give. Moreover, this process has one great advantage to re- 
commend it—that I have been able to take dozens of negatives of 
each special feature, and that from scores of specimens from each 
zone, and by this means I have obtained a broader and more truly 
comparative idea of such features than could be secured by merely 
glancing at the specimens with a lens. Such is the advantage of 
the permanent photographic record over the fleeting mental im- 
pression. The cost of obtaining equally numerous figures through 
the medium of a draughtsman would be prohibitive. 

The results embodied in this paper have been arrived at under 
difficulties, as they have absorbed most of the small leisure of a busy 
professional life during the last four years. They are advanced, 
after careful study, in the hope that they may prove of value both 
to the amateur and to the professional geologist. 

For the last three years Mr. C. Davies Sherborn has accompanied 
the writer in the field and, both there, and in the study, has seen the 
growth of the writer’s ideas, and has helped to verify his statements. 
To him, before all, the writer desires to express his gratitude for 
friendly and stimulating interest. 

Dr. Barrois, Mr. E. T. Newton, Mr. W. Hill, Mr. Jukes-Browne, 
and Mr. Henry Woods have gone over the results in the most 
patient manner, and have seen most of the specimens, and thanks 
are due to them for their kindly interest and suggestions. To 
M. Jules Lambert, M. V. Gauthier, Dr. J. W. Gregory, Mr. C. Griffith, 
Mr. Meyer, Mr. G. E. Dibley, and others, the writer is indebted for 
much assistance in the matter of specimens, literature, and strati- 
graphical information, which have greatly helped the enquiry ; and 
on this head he would give cordial recognition to the generosity 
which has prompted Major-General Cockburn to place his large and 
beautiful collection of Dover Micrasters at the writer’s disposal. 

To all these friends the writer is very grateful, and his sincere 
hope is that this ‘paper will be found of use to those whose friendly 
interest has been of so much service to him. 


EXPLANATION OF PLATES XXXV-XXXIX. 
PuaTE XXXYV. 
This plate is intended to demonstrate that certain dominant profile-shapes 


persist throughout the zones, in all species contained in the zones mentioned, 
whether they be broad or narrow forms. For full explanation, see p. 509, 


Zone of 
Micraster 


yf 


ter 


cor-angulnum. 


—————— ee 


nar1ium. 


_—_ 


20S RRR AI 


SRA STOR OORRRRRENRORN EO ROR RRRRRE O 


oo 


Se 


Zone of 
Micraster 
cor-testudinarium. 
ae 


planus 
-bovis are from the 


Zone of Holaster 


(several of the M. cor 


Zone of 
Micraster 
cor-anguinum. 

: Sx 


Terebratulina gracilis-zone). 
“.. 


Quart. Journ. Geol. Soc. Vol. LV, Pl. XXXV. 


vu—WV. 6 


vi—W. cor- 


v— WM. cor- 
testudinar 


iv—WM. precursor. 


11— WM. cor- 
testudinarium. 


li—_ precursor. 


i—1 to 4= WM. 


1’ to 5/= WM. Leshke 


i 
\ 
| 


QUART. JOURN. GEOL. Soc. VOL. LV. PL. XXXVI. 


; 


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QUART. JOURN. GEOL. SOC. VOL. LV. PL. XXXVII. 
4 x5 


X ez 


RN, 
‘GAS 
17, 

“ Oa 


Arthur Rowe. Photomicr. : BEMROSE & SONS, LT? DERBY & LONDON. 


‘ ‘eae A 
c + % > a 7 * - ma 
’ " el A = g Ab 
a . i «én 
i | aa eh te 
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QUART. JOURN. GEOL. SOC. VOL. LV. PL. XXXVIII. 
| 5 -xes 


Wares wee Oe it 
OW 1 we « ‘é, & / 
Ret ae 
Sey a ye 
ae ee aa 


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4 be 


BEMROSE & SONS, LT® DERBY & LONDON. 


QUART. JOURN. GEOL. SOC. VOL. LV. PL. XXXIX. 
e xis 


Arthur Rowe. Photomier. BEMROSE & SONS, L™® DERBY & LONDON. 


Vol. 55. | DR. A. W. ROWE ON THE GENUS MICRASTER, 545 


Fig. 


Fig. 


Fig. 


Lie 


. ‘Smooth ’type. MM. Leskei of average size, zone of H. planus, Dover. 


bo 


oO - 


“I 


co mnt! 


CC~IS. or OOD 


D om Pope 


Prats XXXVI. 
Anterior paired-ambulacra. 
[ Figs. 1-6 are of low-zonal forms; figs. 7 & 8 of high-zonal. | 


‘Smooth’ type. Mécraster cur-bovis of medium size, zone of Terebratu- 
lina gracilis, Dover. X54. 


x53. The roughness in the centre is due to the base of a Ramulina. 


. ‘Sutured’ type. M. precursor of medium size, zone of Aolaster 


planus, Dover. X5. 


. ‘Inflated’ type. M. precursor of medium size, zone of M. cor- 


testudinarium, Beachy Head. 53. 


. ‘Inflated’ type. MM. precursor of medium size, zone of M. cor- 


testudinarium, Dover. To show the incipient invasion of the inter- 
poriferous area by granules of the interporous ridge ; also the arch 
between the upper paired-pores, passing into the trumpet-shaped 
expansion over the pores. X53. 


. ‘Subdivided’ type (low-zonal). MM. precursor of medium size, zone 


of M. cor-testudinarium, Beachy Head. 'To show the division in the 
arch between the upper paired-pores. x53. 


. ‘Subdivided’ type (high-zonal). M. cor-anguinum of medium size, 


zone of M. cor-anguinum, Gravesend. 'To show complete invasion of 
the interporiferous area by granules of the interporous ridge. X53. 


. ‘Divided’ type. MM. cor-anguinum of medium size, zone of M. cor- 


anguinum, Gravesend. X53. 


Puate XXXVII. 
Single ambulacrum of WM. cor-bovis, zone of T. gracilis, Dover. x5. 


. Single ambulacrum of WM. Leskez, zone of H. planus, Dover. 5}. 
. Single ambulacrum of M. precursor, zone of H. planus, Dover. X54.' 


Single ambulacrum of M. precursor, zone of M. cor-testudinarium, 
Beachy Head. X53. 


. Single ambulacrum of M. cor-anguinum, zone of M. cor-anguinum, 


Gravesend. X53. 


. Base of M. precursor, lower third of M. cor-anguinum-zone, Dover. X24. 
. Base of M. precursor, zone of M. cor-testudinarium, Dover. X23. 

. Base of M. precursor, zone of H. planus, Dover. X24 

. Base of M. cor-anquinum, zone of M. cor-anguinum, upper two-thirds, 


Gravesend. x 24. 
Puate XXXVITI. 


. Base of M. Leskei, of average size, zone of H. planus, Dover. 
. Detail of plastronal tubercles of M. Leskei (same specimen). X8&. 
. Peristome of M. Leskei, zone of H. planus, Pinhay, South Devon. x41. 


Peristome of passage-form between M. Leskei and M. precursor, 
H. planus-zone, Dover. X44. 


. Base of passage-form between M. cor-bovis and M. Leskei, H. planus- 


zone, Dover. 22. 


. Detail of plastron of M. cor-bovis, T. gracilis-zone, Dover. To contrast 


with fig. 2. x8. 


. Peristome of WM. precursor, H. planus-zone, Dover. 5. 
. Peristome of M. precursor (labrum broken), zone of M. cor-testudinarium, 


Seaford Head. X33. 


. Peristome of M. cor-anguinum var. latior, zone of M. cor-anguinum, 


Gravesend. X44. 
Piate XXXIX. 


. Peristome of M. cor-bovis, zone of T. gracilis, Dover. x4. 
. Base of M. cor-bovis, zone of T. gracilis, Dover. X14. 


. The same. X2. 
. Detail of arched pores in the lateral avenue of pc: ristome of same, x4, 


.G.S. No. 219. 2N 


546 DR. A. W. ROWE ON THE GENUS MICRASTER.  [Aug. 1899, 


Fig. 5. Sub-anal fasciole of Micraster precursor of medium size, Holaster 
planus-zone, Dover. X23. 
6. Sub-anal fasciole of M. precursor of medium size, M. cor-testudinarium- 
zone, Seaford Head. X83. 
7. Sub-anal fasciole of M. cor-anguinum of medium size, M. cor-anguinum- 
zone, Gravesend. All three specimens were picked as being of the 
same size, so that the contrast might be legitimate. x3. 


Discussion. 


Mr. W. Hitt congratulated the Author on the excellence of the 
paper and the admirable illustrations. He hoped that he could 
congratulate Cretaceous geologists also on the removal of a difficulty 
which had troubled them for many years. He recognized in the 
upper part of the Middle Chalk Mzcraster cor-bovis, and in the base 
of the Upper Chalk M. cor-anguinum. In the Chalk between 
the horizons at which these species occurred were a number of 
forms, each differing slightly from the other, some of which he 
referred to M. breviporus and others to M. cor-testudinarium, but he 
had never been satisfied with their identification, and for many years 
it had been felt by himself and others that they were not treading on 
firm ground. Hedid not propose to criticize the characters by which 
the Author distinguished the four species, or the new form WM. pre- 
cursor. The Author had kindly explained to him the guiding 
characteristics of the Micrasters, and he had followed these in the 
field. He could endorse all that the Author had said with regard 
to the gradual change of the ambulacral areas, the tuberculation of 
the test, the character of the mouth, and its position in regard to 
the ambitus; but he was not yet certain as to the stratigraphical 
value of these characters. This point, however, would perhaps 
become clearer when they had the paper before them, and could test 
it in the field. 

Prof. Srerry remarked that the Author’s diagrammatic arrange- 
ment of his specimens in parallel series corresponding to the zones 
from which they were collected, clearly exhibited the vertical 
survival of the gradated forms termed ‘species’; and the photo- 
graphic enlargements of the poriferous zones and other parts 

-of the test had demonstrated the typical characters by which 
the species might be distinguished. There were variations seen 
in every chalk-pit; and he desired to ask the Author whether 
there was, in the vertical series of specimens examined, any 
evidence of variation in the distinctive characters of species which 
would amount to evolution within the genus Micraster. It was 
most desirable to correlate the vertical variation with horizontal 
geographical variation, and to learn whether the horizontal variation 
had any relation to the vertical variation which might challenge the 
identification of horizons in the Chalk by the varietal forms. He 
desired to know which of the specific characters become effaced, and 
where the obliteration has been observed. 

Dr. J. W. Grecory thought this paper of great interest, as 
it applied to the question of the systematic value of the differences 
in the Chalk Micrasters the only method that is likely to yield final 


Vol. 55.] DR. A. W. ROWE ON THE GENUS MICRASTER. 547 


results. For 40 years it has been uncertain whether the varieties 
of Chalk Micraster have been formed by spasmodic individual 
variation, or form part of a continuous variation in time—that is, 
Are they circuli or mutations ? The question could not be settled in 
a museum, or from a priori zoological considerations, as the differ- 
ences in question, if found in recent Echinids, would not be 
regarded as of specific value. ‘The final decision rests on the 
historical method, of zonal collection on a large scale, which has 
been adopted by the Author. The mass of facts in the paper 
would be of the highest value. Some of the differences in question 
are probably due to the depth at which the Micrasters lived. 
He congratulated the Author on founding his Micraster precursor 
on a group of specimens, instead of on a single type. 

Mr. E. T. Newron remarked on the thorough and philosophic 
character of the Author’s methods of work. Having had the 
opportunity of seeing the work as it progressed, and of testing its 
applicability to the determination of the horizons of the Chalk, from 
the Rhynchonella Cuvieri-zone to that of Micraster cor-anguinum, 
he was satisfied that it rested on a sure foundation, and would in 
future be a great help to geologists working in these Upper Cre- 
taceous rocks. 

Mr. G. E. Dretey said that he spoke as a tield-worker, though a 
comparative novice, and could most thoroughly appreciate the lucid 
diagnostic features which the Author had so admirably put before 
them. He felt sure that the many perplexing points regarding 
the genus, especially in those species ranging from M. cor-bovis 
upward to WV. cor-anguinwm, would now disappear. He placed great 
faith in the Author’s work, as, in sending specimens to him from 
various areas and zones, he had in every case determined their exact 
zonal derivation. He most heartily congratulated the Author on his 
valuable paper, and at the same time tendered his thanks to him for 
his kindness in determining many of his (the speaker’s) specimens. 

The Presipent, Mr. C. D. Suerpory, and Prof. Soxzas also spoke. 

The Auvruor, in answer to Prof. Seeley, said that he could trace 
a perfect transition, not only in the general shape of the test, but 
that the transition applied to every feature of the test, even in the 
minutest detail. The Author added that specific types were rare, 
and that transitional forms preponderated. He further stated that 
though the facies of the Micrasters might vary slightly in different 
localities, still the observations on the essential features of the test 
were perfectly reliable, even in sections so far apart as Dover and 
Beer Head. In reply to Mr. E. T. Newton, the Author pointed out 
that he had been forced by lack of time to leave out the discussion 
of the group of WM. precursor, but that the arguments in. favour of 
such a group were fully set forth in the paper. He also replied to 
various remarks made by other speakers, and, in conclusion, thanked 
the Fellows for the reception accorded to his paper. 


2Qn2 


548 MR. W. GIBSON AND DR. WHEELTON HIND ON THE [ Aug. 1899, 


33. On the AcctomERATES and TuFrs in the CaRpontFERovs LimE- 
stonE Series of Coneteron Ener. By Watcor Grsson, Esq., 
F.G.S., and Dr. Wueetron Hinp, B.S., F.R.C.S.,F.G.8. With 
an APPENDIX on the PerroerarHy of the Rocks by H. H. 
Arnotp-Bemrost, Esq., M.A., F.G.S. (Read June 21st, 1899.) 


1. Historical Summary. 


ConTEMPORANEOUS igneous action during the deposition of the Car- 
boniferous Limestone has long been known and described from 
several parts of England and Ireland. In the Annual Report of 
the North Staffordshire Field Club for 1898* and in the present 
volume of this Journal,’ volcanic activity has been described as 


4 inches to 1 mule. 


SCALE OF FEET 
0 1000 


c (2 
“ / 
Ss a 
/ 


a = Limestone. Y= Grit. 
6 = Shales and thin limestones. g = Shales and thin earthy limestones. 
ce = Agglomerate and tuff. h = Shales and grit. 


d = Shales, limestones, and tuffs. ¢ = "Third Grit: 
é = Shales with coal. 


1 Wheelton Hind, ‘ Deser. of Section in Carb. Limest. Shales at Tissington, 
on Buxton & Ashbourne Ry.’ Ann. Rep. & Trans. North Staffs. Field Club, 
vol, xxxii (1897-98) pp. 114-116. 


* H. H. Arnold-Bemrose, ‘Geology of the Ashbourne & Buxton Branch of 
the L. & N. W. Ry.: Ashbourne to Crake Low,’ pp. 224-238. 


Vol.55.] | AGGLOMERATES AND TUFFS OF CONGLETON EDGE. 549 


occurring at Tissington towards the close of the deposition of the 
Carboniferous Limestone. The object of the present paper is to 
bring forward distinct evidence, hitherto unsuspected, of volcanic 
action of the same age on the western slopes of Congleton Kdge, 
20 miles west of Tissington. 

This bed of igneous rock, though well exposed in an old quarry, 
seems hitherto to have escaped notice. It is omitted from the 
section in the Geological Survey memoir’ and not mentioned in the 
text. The late Dr. Garner may possibly refer to it in his ‘ Natural 
History of the County of Stafford, 1844, p. 212, where he says :— 
‘On the western side of the coalfield, towards Mow Cop, there like- 
wise occurs a rock which appears to owe its formation in part to 
igneous action. This is of a lively green colour, very hard, and 
enclosing many roundish pieces of bright red rock, which, however, 
are also seen in some of the grit of this spot.’ But this description 
scarcely agrees with the coarse angular nature of the agglomerate at 
present exposed in the quarry at the foot of Congleton Kdge. 
Again, in the appendix to the same work, p. 45, he says :—‘ The 
Astbury limestone at the west foot of Mow Cop is rather peculiar, 
being dark in colour, with blotches of red and green.’ This may 
refer to some of the included fragments of tuff, or to the pockets 
of hematite and other minerals which occur in the heart of the 
limestone. 


2. General Structure of the Area. 


The area under discussion lies in the Geological Survey map, 
Sheet 815.W. 

The ridge of Mow Cop, with its northern extension, Congleton 
Edge, forms the boundary between Staffordshire and Cheshire, and 
reaches an elevation of 1101 feet above Ordnance datum on Congle- 
ton Cloud. The ridge, whose scarp faces west, is capped by two 
beds of Millstone Grit, considered to represent the First and Third 
Grits, separated by a small amount of black shales. Below the Third 
Grit to the base of the hill a narrow dome of Carboniferous Limestone, 
lying in the midst of the so-called Yoredale Shales, is exposed in an 
old quarry. Immediately to the west, the Lower Carboniferous rocks 
end off against the Red Rock Fault, while the whole country is 
covered with a thick mantle of Glacial clays and sands. In order to 
bring out clearly the exact age and relationship of these igneous 
rocks to those of known age, asmall tract—a little under one square 
mile—has been carefully examined and mapped on the 25-inch 
scale, and a reduction of this map is reproduced in fig. 1. The 
authors were so fortunate as to obtain, in the quarry-section of 
agglomerate, the help of Mr. Arnold-Bemrose, who also kindly 
furnishes some notes on the petrography of the igneous rocks, 


1 *Geol. of Country round Stockport, Macclesfield, Congleton, & Leek,’ 
Mem. Geol. Surv. 1866, pp. 9, 47, 72 & 73. 


550 MR. W. GIBSON AND DR. WHEELTON HIND ON THE | Aug. 1899, 


3. Succession of Limestone and Igneous Rocks. 


(a) Quarry-section, Astbury Limeworks.—The quarry is 
about 1 mile north-east of Mow Cop Station and is represented on the 
Geological Survey map by a small patch of dark blue, ending off 
to the west against the Red Rock Fault, and lying between this 
fault and another to the east, in the midst of beds mapped by the 
officers of the Geological Survey as Yoredale Shales. 

The limestone was worked for a long time in an open quarry ; but 
of late years these workings have been abandoned, and the limestone 
is now obtained by an adit commencing on the west in Triassic 
rocks. The limestone is massive and thickly bedded, containing 
corals and encrinites and the fossils usually found in the Carboniferous 
Limestone, among them Chonetes papilionacea. A detrital bed, con- 
taining rolled shells, occurs in the upper portion. The massive lime- 
stone is shown in the old quarry to be overlain by calcareous shales 
with thin bands of impure limestone, a series of passage-beds which 
is generally found to succeed the Mountain Limestone massif in 
North Staffordshire, Derbyshire, and South-west Yorkshire. 


Fig. 2.—Section along CD (see map, fig. 1, p. 548) on the scale of 
25 inches to the mile. 


Astbury 
Houses. Limeworks. 


OTA 
“Aue 


7; 
4 
“OU 
VI t 
Wiig ; 
7 fl, 
Yi Uy 
A Wtsslh fh fe 
CU 
¢ d 


a = Limestone. | d = Shales, limestones, and tufts. 


Cc 


= Shales and thin limestones. é = Shales with coal. 
c = Agglomerate and tuff. 


At the present day the quarry is much overgrown by grass, 
especially on the west side. The igneous rock, however, is well 
exposed in the north-eastern corner in a face about 25 feet high and 
160 feet long, while recent land-slipping has brought to light other 
sections on the eastern and south-eastern sides. . 

The mass in the cliff-section is an agglomerate—consisting of 
angular fragments of green tuff—often vesicular, embedded in a 
greenish calcareous matrix. Fragments of marmorized limestone are 
not infrequent, and in some places there are corals and other fossils 
roughly occupying certain layers in the mass. The rock does not 
disintegrate rapidly, but weathers on the outside to an ochreous 
colour. It is much harder in the cliff than in any of the other 
exposures. The agglomerate is underlain by thin limestones and 
calcareous shales ; the dip is into the hill, or eastward. The top of 
the mass is not seen, being covered by grass and débris. Ni 

South of the cliff occurs a gap of 150 feet in which no 
rock is visible, while south-west of the gap thin limestones and 


Vol. 55.]  AGGLOMERATES AND TUFFS OF CONGLETON EDGE. 551 


calcareous shales are exposed on the same strike with the 
agglomerate. This suggests a neck, the gap representing the actual 
site of the vent. No further evidence is obtainable at the surface, 
and unfortunately the underground workings cease 58 yards before 
the critical point is reached. There are some slight appearances at 
the surface of a fault, but no absolute proof. The limestones and 
shales can be followed for the next 150 feet, then all exposures are 
lost beneath a slipped mass of stiff chocolate-coloured Boulder Clay. 
The dip is seen to be changing from east to south-east. South-west 
of the slipped mass of clay the thin limestones and shales are exposed, 
and above them liesathin band of calcareous tuff, overlain by 10 
feet of agglomerate with encrinites. This agglomerate is much 
decomposed and of a deep ochreous colour, but the evidence is not 
sufficient to settle whether this is the same band as that seen in the 
north-eastern corner of the quarry. Above the band of agglomerate 
lies a hard dark shale, and 15 feet above this a coal 1 foot 6 inches 
thick is seen, the intervening beds being hidden beneath rubbish. 

The dip is here nearly due south. The agglomerate ends off 
against a small fault with a northerly downthrow, but thin limestones 
and shales are again seen in the extreme south of the quarry. 


(6) Brook-section 250 yards north of the Quarry.—No 
signs of igneous rocks are met with south of the quarry, the dip bring- 
ing in higher beds, but about 250 yards north of it a small stream 
shows the following apparent descending sequence :— 


[The letters and numbers refer to specimens examined by 
Mr. H. H. Arnold-Bemrose: see pp. 557-558. ] 


Ne OG Oe MitceOUS LIMOESLONE «cao. c0scccee scoceess cvesmeeeassenconan 
Gap, a few feet. 
Sere D Vetch) ak ie ee ne PRE YT ee odie 
lard caleareous nodular rock ©.2..2...ccese.cecdsteeene 
Gapr. ccs. Be sree Ned wieviaiiae abn Sonn corbin ie Ak eae ae aaa 
F 1065. Flaggy calcareous sandstones, passing into shale ...... 
Productus- and encrinite-limestone —.............eeseeeee 
Black shales, with nodular concretionary limestone ... 
IPMORIMILE-IMNESLONE: . wij..cuc esas veka catneskiegeeee es acme 
HOGS WnIACCOUSLIIIMESLONE. \icaces coada. se cswusuecaemecsstccnmenet 
LOGIE “Mataremne MMeSstOUS 2... 22.00 cccweeancecwuaneuevemsseetes 
1062. Tuff, much decomposed ; no fossils. 
Exposure obscured towards bottom ..........seseseeeeeeees 120 
EAD ee oe hac pane :desioon dane cn sco cap cone vannipanacsescnasp aan 130 
1063. Coarse tuff, with fragments of limestone ........-..-006 100 
1011. Tufaceous limestone, with fossils ..............cccceeceeeree 2 
1056. Well-bedded Galewroons GREET. ste eed onskeeee eee se 
Massive Timestone, <a. «cseatsiceeic.s ceeeeienneee aaebekis eae eae es 
HRP GLEE. 5 <.s'. «'sws sogiaadecamentan semana eee see eee eee se canes 
105i. Cataceous limestone: ~s..0¢02.cccsearccaacos teen eee oe nee 
TOGSe Well-bedded calcareous Gulf 22.2 oo. cc. 2s seuss bees oe: - 
1058. Thin hard tufaceous limestone — ......ceccecceccccccccccces 
MORE EMT AL 25 <2 oinicn tc csigpibnale da Wee Baan 0 eee cake cE baw « 
Bees estes 3 Siaiaetee eae J eeeae SNe a BER ete cielan oe 
1010. Hutheosae TaafGSbOie fasavence vchwih ote ati Mee atc oe cion odd 
1059) “‘Duil, coarsely laminated 2: .. acdc ee csacetees tnceccto. 00s 
_ Limestone passing into calcareous tuff ..............e008 
Yellowish-brown tuff ......... OSE oe OE ee : 


bo 
=} 
Bo 


be 
. rr 
ROrWEaANOoOO Be 
(S1- 


Hal 


D © o> 


— 
SSOCOCCONWFRMAOOOOCOCSOSD OOWononowa oO 


mee] Sxree waacfo 
— 
OnNoNWNWRCrH oO 


+ 


552 MR. W. GIBSON AND DR. WHEELTON HIND ON THE [ Aug. 1899, 


same bed on the east and west 
sides of the dome, and the greater 
width of outcrop is probably due to 
the stream following the same bed 
for some distance along the strike. 

Towards the lower part of the 
section the strata are thrown into 
gentle folds. This is diagrammatic- 
ally represented in fig. 4(p. 553). 
There seems, however, to be a greater 
number of beds of tuff exposed in 
the lower part of the stream than 
are seen either in the quarry or 
towards the summit of the section. 
The stream-section places beyond 
doubt the age of the volcanic out- 
burst at the close of the Carboni- 
ferous Limestone episode. 


dic 4g The stream thus shows a much 
ee 8 eyo more complete section than that of 
Ba H Uy the quarry, but it is believed that 
this is in part deceptive: thus the 
Bos Wf... apparently thick beds of tuff seen 
Bas en ia fo in the stream are regarded as the 


SSF Cs 


Road. 


=_ 


SS 
Shales and thin earthy limestones. 


SS = 


I= 


Shales with coal. 


4. Succession between Top of 
Limestone and Third Grit. 


(a) Brook-section in Lime- 
kiln Wood.—In the brook-section 
north of the quarry it has been 
seen that the tuff-beds and thin 
encrinital limestones are succeeded 
by a few feet of shaly sandstones 
and then by a thin coal. By means 
of the sections on the mountain- 
road leading from Limekiln Farm 
on to the moor, and the streams 
flowing down the northern margin 
of Limekiln Wood, an almost con- 
tinuous section between the lime- 
stone and the Third Grit can be 
obtained. 

Near the southern edge of the 
limestone-quarry, in the roadside 
leading from Limekiln Farm, a coal 
1 foot 6 inches thick, passing under 
greyish-black shales, is exposed. 
The dip is not very high, showing 
that the summit of the dome is 


e 
ie 


Tuff. 
Shales. 


Astbury 
Limeworks. 
Cc 
d 


Fig. 3.—Section along line EF (sce map, fig. 1, p. 548) on the scale of 20 inches to the mile. 


Houses. 
6 = Shales and thin limestones. 


a = Limestone. 


Vol. 55.] | AGGLOMERATES AND TUFFS OF CONGLETON EDGE. 509d 


close at hand. The shales that succeed have a fairly high dip, and 
are about 50 feet thick. These pass up into lavender-red shales, 
and red grits, succeeded by about 70 feet of a hard close-grained 
grit, with red spots and resembling in lithological characters the grits 


Fig. 4.—Section along line AB (sce map, fig. 1, p. 548) on the scale 
of 25 inches to the mile. 


a = Limestone. 
6 = Shales and thin limestones. 
c = Agglomerate and tuff. 


d = Shales, limestones, and tuffs. 
é = Shales with coal, 
F = Red Rock Fault. 


of the Millstone Grit Series. The road-section shows more shales, 
and then a hard calcareous mudstone. The succession above this is 
best shown in the stream running alongside Limekiln Wood :— 


Feet Ins. 

HAR EME MOM AIUIESCONE | 5152512), cebedessonescon codon staneeademensnanene (i! 
AS HASH S GU, Bos 25 jasc Za snsaduch «aaa daiceete dasuhee snaepebeeeaeeea as 200 0 
Grey shales, hardened im places).....:...<:0:se<qs0> aq fscenseance 6 0 
Dark sandy shales, with numerous thin ferruginous bands... 50 0 
SS RSLS CN sce cates oa cing! edeae aide sesenee oadeer ects bee meee age 40 0 
ABER B ELL OCs ects cavoebor este veves sc ontacacsaecdensencccee caemeeEee eae 10 

99 BAU oe Fa) a Soaks Sa dadivledv sv da cawoReaey sidauen ape ee te rae 21,0 
RHE SRA CBr b dla ocstgae as docinas mnnaieo ciate bacon «nds saeeyag epee aoe 16 0 
ESET SAMO ERODE bp isccccucctadoamve~soidten saat cen nose Snadeiee tase eee 0 
SSE REALS ante oat e ba onset pacnninareacnn spe donne suena apa ort D esi 45 0 
EhiniHagsmy BARESLONG ? 2.5.62 sis loss «cmbedaratae sedecemnenndeusee: 50 0 


The section in the main stream at this spot is hidden, but it is 
continued in a tributary stream to the south, where deep narrow 
gorges have been excavated :— 


Feet 

Flags, as in the above section .............00+6+ 50 
Ui p on atta colon mae oe eee cane aedaae earn eee 150 
ee | Rema as Sear ee - UNNI OU ilies Ms EP ay ae {2 
Shales sco eee he ence ce ee enemas 30 
Grit. Sea cee ee 8 
Shales! (2:31. See ae ee 80 
Grit) sie sstssiee tei eee eee 9 
C1 | Pe ee ee nner ome Mey Gee ne MEE SS eee 30 
GPG icc sc) ce scccaesecckereors Mtoe eat eee oeeee eee 5 
SHES. “oa tecvas coher eae ar ee ae ee 8 
Grit 2S eee eee 9 
Gaps oscil buenos sakes ceatote: Soee tear aeet oceeees 120 
Shales) csu,ccteusccagios sens taancae satan eee ee 30 
GIG: ok dds BRO ee ees eee ee ee LAL, 8 
fo) Ce Gene Pare Cen AW Cena we Bien 2 tc LIM he oe 35 


554 MR. W. GIBSON AND DR. WHEELTON HIND ON THE [Aug. 1899, 


The dip is often as high as 65°, and is seldom lower than 55°. 
The north-easterly strike remains constant. 


(5) Quarry below the Third Grit, near roadside leading 
from Gillow Heath to Congleton.—Many of the grit-bands 
can be traced to the north-east for several hundred yards. In this 
direction, about a mile distant from Limekiln Wood, a quarry 
mentioned in the Geological Survey memoir’ has of recent years 
yielded a varied marine fauna.” A measured section shows, in 
descending order, the following strata :— 


Dull grey and yellow clay, with blocks of grit, 0-5 feet. Feet Ins. 


Rotten limestone, made up of Orthis resupinata .........ceceeeeee 5 2 
GRE sss Peaiae te al enlemen seek ot eeatian Seindaly Sg ORG at lac owame'eeeenee 10 
Shales, grey ...... Be Ades < saMeue Re colar uaico in ade ore te fash ainda ME 3 0 
Shaies with thin slightly calcareous nodules ............seceeeeeeee 0 9 
Hard, fine, erey Sand y-SmAles «a. 125.08 cacnderen ees saictt Oswehmetonaeaeen O 4 
Shales, with eleven bands of calcareous nodules, containing a 

HICH Marie FAUNA. 2 gcsscc c ooansateedsak sectcanAnekieiodhnsGognaw anes 7 
Rather dark shales, with two lines of calcareous nodules......... 3 0 
Shales: with "GO72G376e8 scan. snctace dere ctee ts a eetcance rasta ettne eae 0.3 
Darker calcareous shales coarsely laminated, with Glyphioceras 

spirale, Posidongella Mevrs, OUCy’ —lgen. i vaste sen nciedtessakecnasoedsaer 0 
Shales, with calcareous nodules ; marine fossils ............ 22.0. 4 0 
Coal, about 3 inch, twisted into joints of grit. ..........ceceeeeeeee 0 Of 
Gannister-like @ritiy, &, eacsasetidc.ciascaitcaxe te akenien hes wadaasenheeee BY 38 
Gannister grits and shales, with plant-remains .................. 33 7 


The dip is 45° to the south-east, giving with the rise in ground 
and distance from the Third Grit a thickness of about 500 feet of 
strata, chiefly shales, between the Orthis resupinata-limestone and 
this grit. The shales between the bands of grit are much crushed, 
showing that they have been subjected to considerable pressure. 

The strata between the limestone-massif and the Third Grit are 
thus seen to consist of two portions—an upper series of thin grits 
and shales with a marine band in the middle, and a lower series of 
shales and thin, hardened, slightly calcareous mudstones, apparently 
unfossiliferous and having a massive grit 70 feet in thickness near 
their base. The hardened calcareous mudstones possibly represent 
the thin limestones mapped in Staffordshire and Derbyshire by the 
officers of the Geological Survey as occurring some few hundred 
feet above the main mass of Carboniferous Limestone, and are 
representatives of the Pendleside Limestone of Lancashire and 
Yorkshire. 

The twisted nature of the Astbury Carboniferous Limestone- 
inlier with its compressed structure, the crushing of the shales 
between the bands of grit seen in the quarry below Congleton Edge, 
and the evident folding and crumpling of the shales in the brook- 
section north of the limestone-quarry, make it possible that the beds 
between the Third Grit and the limestone may owe part of their 
thickness to reduplication by overfolding ; but we think that the 
‘stream-sections in Limekiln Wood, with their distinct divisions 


1 *Geol. of Country round Stockport, Macclesfield, Congleton, & Leek,’ 
Mem. Geol. Surv. 1866, p. 92. 

* Wheelton Hind, Geol. Mag. 1897, p. 208, and ‘ Brit. Carb. Lamellibr.’ 
Monogr. Pal. Soc. pt. ii (1897) p. 93. 


Vol. 55.]  AGGLOMERATES AND TUFFS OF CONGLETON EDGE. 5d0 


into a grit-and-shale series above and a shale series below, and with 
no demonstrable reduplication of any one bed, render this unlikely. 

Beyond indications of the strata having been considerably squeezed 
we find no evidencefor the complicated system of faulting, represented 
on the Geological Survey map as surrounding the limestone-inlier. 
The fault on the Survey map represented as cutting off the limestone 
series to the east does not exist, and was probably introduced to 


Fig. 5.—Section along GH (see map, fig. 1, p. 548) on the scale of 
4 inches to the mile. 


Red Astbury : 
Rock Lime- Quarry Third 
Fault. works. Fossils. Grit. 


Glacial Sands and Clay! 
=== Se rate SS 
figias, 2 a bedef g 
a = Limestone. g = Shales and thin earthy limestones. 
b-f = Shales, limestones, agglome- h = Shales and grit. 
rates, tuffs, and grit. 4 = Third Grit. 


account for the absence of the great thickness of strata assumed to 
exist elsewhere between the limestone and the Third Grit. Towards 
the north-western portion of the inlier, as already stated (p. 552), 
minor folds exist in proximity to the Red Rock Fault, and in the 
stream a little farther north the shales are much disturbed, but in 
some cases this is due to the different resistance offered to tangential 
pressure by the more massive beds, whether limestone or grit, and 
the thin fissile shales. 

So far as the evidence goes, there seems no reason for placing the 
strata between the limestone and the Third Grit in the Yoredale 
division, while, on the contrary, the fauna of the marine band and 
the presence of numerous grits of Millstone Grit type, containing 
plant-remains, point to their connexion with the Grit Series of the 
Carboniferous system. 


5. Summary and Conclusion. 


The occurrence of contemporaneous volcanic action towards the 
extreme summit of the Carboniferous Limestone exposed in the small 
inlier on Congleton Edge is interesting, as it brings the rocks into 
close relationship with the similar rocks in Derbyshire. Whatever 
opinion is held regarding the position of the vent, or the age of the 
beds lying between the Third Grit and the main limestone, there 
is no doubt that the volcanic tuff fell into the Carboniferous sea at 

.the time when the main oscillatory movements which characterized 
the later Carboniferous period began. 


556 MR. H. H. ARNOLD-BEMROSE ON THE [Aug. 1899, 


Apprnpix on the Purrocrapuy of the Rocxs of Coneteton Epex, 
By H. H. Arnoxip-Bemnrose. 


1. The Agglomerate in the Quarry. 


TE following specimens from the agglomerate in the quarry were 
collected by the writer and examined microscopically :—Two of hard 
and three of softer agglomerate, one block of vesicular rock, and two 
blocks of limestone embedded in the agglomerate. 

A hard agglomerate (978)' consists of lapilli of irregular 
shape, set in a brown matrix, containing a few minute lapilli and 
probably Monticulipora. The lapilli are very rarely vesicular, and 
then only contain few vesicles. The fragments with few or no 
vesicles contain altered felspar-laths and olivine in a dark base, 
which is almost isotropic. ‘The lapilli are often surrounded by a 
vein-like fibrous calcite. 

In another specimen of hard agglomerate (979) the lapilli are 
in a remarkably fresh state of preservation. ‘They contain olivine- 
phenocrysts altered to calcite and sometimes to serpentine, with 
augite and felspar in a yellow isotropic base. The augite is 
fresh, and occurs in idiomorphie crystals and prisms, often arranged 
in groups or clusters. The felspars are fresh and clear, and have 
a sharply-defined outline. A few small vesicular and non-crystalline 
lapilli are present. The lapilli are cemented together by a limestone- 
paste, in which occur foraminifera and other organisms, together 
with a few fragments of augite and felspar and a subangular quartz- 
grain. The rock may be described as a basalt-tuff. 

A piece of thesofter agglomerate (981) consists of fragments 
of dolerite in a limestone-paste, containing veins of calcite and traces 
of organisms. The igneous fragments consist of pseudomorphs of 
felspar and olivine in a reddish matrix, which is in most cases free 
from vesicles. A few small vesicular lapilli without crystals are 
present, and have in many cases undergone alteration. 

A second specimen of the softer agglomerate (982) contains 
vesicular and non-crystalline lapilli altered to calcite. Other lapilli 
consist of altered felspar-laths with ragged ends and pseudomorphs 
of olivine, in a red (sometimes almost black) matrix. The long axes 
of the felspars are generally parallel one to another. A small 
quantity of unaltered augite is probably present in one lapillus. The 
cementing-material contains Monticulipora. 

A third specimen (983) consists of lapilli in a cement of smaller 
volcanic detritus. The larger fragments consist of pseudomorphs 
of olivine and felspar-microliths, sometimes in a dark red, and at 
other times in a lighter, isotropic matrix with oxide of iron. The 
smaller lapilli are vesicular and contain no crystals. 

A vesicular block from the agglomerate (980) 1s a much- 
altered rock, consisting of pseudomorphs of olivine and felspar, 


1 The numbers in parentheses are those of the slides in the writer's 
collection. 


Vol. 55.] | PETROGRAPHY OF THE ROCKS OF CONGLETON EDGE. 557 


and perhaps of augite, in a yellow or red matrix. The vesicles are 
large and sometimes contain small lapilli. The block is probably a 
fragment of lava. 

Another block (984) is of a dark and fine-grained limestone 
surrounded by, and passing into, green lapilli cemented by calcite. 
The dark limestone contains a few vesicular and non-crystalline 
lapilli altered to calcite, and two fragments of felspar. The tuff 
adherent to the limestone consists of lapilli and organisms mingled 
together. The lapilli are sometimes vesicular and free from crystals, 
and are often more or less rounded. In other cases they contain 
felspar-microliths and have a yellow isotropic base. Numerous 
strings of calcite traverse the microscopic slice. 

A block of coralline limestone from the agglomerate (985) 
is composed partly of a large coral, which occupies a considerable 
area. of the thin slice, and partly of a limestone containing fora- 
minifera, Monticulipora, and other organisms, with afew lapilli. The 
latter are sometimes vesicular and non-crystalline, and in other cases 
contain felspar-microliths and probably small olivine-pseudomorphs. 
They are often isotropic, and many of them are subangular in 
shape. 


2. The Tuffs in the Brook north of the Quarry. 


The following seventeen specimens were obtained by Dr. Hind 
from about 500 yards north of the limestone-quarry (see p. 551) 
and in the quarry itself. 

Specimen C, tufaceous limestone (1011), from a bed 2 feet 
thick, is a rock containing fragments of organisms and pieces of 
previously consolidated limestone and lapilli. The lapilli, which 
for the most part have undergone alteration, are in some cases 
highly vesicular; and in others contain a few felspar-microliths and 
probably pseudomorphs of olivine. 

Specimen B, tufaceous limestone (1010), from a bed 2 feet 
thick, is hard in a hand-specimen. It consists of a fine-grained 
partly crystalline limestone, with a few organisms and some 
lapilli. Some of the latter are vesicular and non-crystalline, others 
gontain felspar-microliths. The fragments of igneous rock are 
often altered to calcite. 

Specimen A, calcareous tuff (1009), from a bed 1 foot 11 
inches thick. It contains organisms and tuff-fragments. The 
latter are plentiful, and form the greater portion of the thin slice. 
Many of them are vesicular and altered to calcite. Some of them 
contain felspar-microliths and pseudomorphs of olivine. They are 
not in a fresh state of preservation, and are often subangular. 

Specimen D, tufaceous limestone (1012), a few feet below A. 
It is a limestone containing corals, foraminifera, and other organisms, 
with a few small lapilli, which are often altered to calcite, and not 
always readily distinguished trom the limestone surrounding them. 
Few of them contain felspar-microliths. 


508 MR. H. H. ARNOLD-BEMROSE ON THE [Aug. 1899, 


Specimens 


V 1056, 6 feet below 1011 ; X 1061; 

T 1057, above 1009 ; 1068, between X and Y ; 
R 1058, below 1009; 1066, from the bottom of 
N 1060 ; the quarry, 


are tufaceous limestones, more or less alike and much more de- 
composed than A, B,C, & D. They contain traces of fossils ; the lapilli 
are generally altered to calcite, and felspars are rare in them. 
Specimen 1061 contains Gervanella, and in 1066 a few angular 
fragments of quartz are seen. 

P 1059 is a coarsely laminated tuff, 5 feet thick. It consists 
of more or less rounded fragments of igneous rock, limestone, and 
fossils. The lapilli are either vesicular and non-crystalline, or 
contain pseudomorphs of felspar and olivine, and are then similar to 
those in 979, but in a much more advanced stage of decomposition. 

M 1062, O 1063, and OO 1064 are in so decomposed a state 
that from a hand-specimen it is impossible to tell whether any of 
them is a piece of a lava-flow or a block of lava from a tuff-bed. 
The thin slices examined consist of a massive rock, with pseudo- 
morphs of felspar and perhaps of olivine, which when in a fresh state 
was probably similar to the rock of which the lapilli in 979 were 
formed. 


In addition to the igneous rocks, two specimens of calcareous 
grit were examined. 

F 1065 consists of angular fragments of quartz in a calcite-matrix. 
These minerals are present in nearly equal proportions. There are 
also a few fragments of a slightly dichroic mineral, which is probably 
mica. The slice is traversed by veins of crystalline calcite. This 
specimen is very similar to a calcareous grit occurring in the Kinder 
Scout Grit, at Crich (Derbyshire), which, in addition to quartz, 
contains a few felspars and a small quantity of mica. 

Specimen 1067 is a similar rock, containing fewer quartz-fragments 
and traces of fossils in a partly calcareous matrix. In these speci- 
mens the quartz-grains are always angular, generally isolated one 
from another, and have not a crystalline outline like those which 
are found in the Mountain Limestone. The quartz often contains 
inclusions, and apparently is not a secondary product. 


3. Summary and Conclusion. 


The igneous rock in the quarry is either a volcanic agglomerate 
filling a vent, or a thick deposit of very hard, coarse, and tumultuous 
tuff, which is probably not far distant froma vent. The section in 
the brook consists of limestones, some of which are tufaceous, with 
at least two beds or intercalations of tuff. This proves conclusively 
that there was volcanic action contemporaneous with the deposition 
of the limestones. 

The lapilli are of two kinds—the originally glassy vesicular or 
palagonitic type, without crystals, and the basaltic or doleritic type, 


Vol. 55.] § PETROGRAPHY OF THE ROCKS OF CONGLETON EDGE. 599 


almost entirely free from vesicles, and containing felspar, olivine, 
and often augite. The two kinds are generally present in the same 
thin slice, but the doleritic type, though common in the agglomerate, 
is comparatively rare in the specimens of bedded tuff and tufaceous 
limestone examined. On the other hand, the vesicular lapilli occur 
more frequently in the latter rocks than in the agglomerate. 

The igneous fragments in the agglomerate are in a much better 
state of preservation than those which occur in the four specimens 
from the bedded and contemporaneous series north of the quarry. 


Discussion. 


Mr. Garwoop was interested to hear that Dr. Hind had recorded 
Chonetes papilionacea from the limestone forming the central area 
shown in the section; he gathered from Dr. Hind’s description 
that this limestone represented the Yoredale Beds of Yorkshire, 
which would show that species to occupy a much higher horizon in 
the Congleton district than in Westmoreland and Yorkshire, where 
it appeared to be confined to the Lower Mountain Limestone proper. 
This added another proof of the difficulties attending an attempt to 
zone the Carboniferous rocks of Britain. 

Prof. W. W. Warts and Mr, H. B. Woopwarp also spoke, and 
Dr. Wueetton Hinp replied. 


560 MISS M. M. OGILVIE [MRS. GORDON| oN THE  [ Aug. 1899, 


34, The Torston-Srrucrure of the Dotomites. By Maria M. 
Oarrviz [Mrs. Gorpvon], D.Sc. (Communicated by Prof. W. 
W. Warts, M.A., Sec. G.S. Read December 21st, 1898.) 


[Pirate XL—Map. ] 


ConTEnTs. 

Page 
Le detroductoty Wemlarkace onc. scntotcacessnteeaeccetae teen 560 
Il. The Anticline of the Groden Pass .....s:.:d:-cssescases ee 566 
ITI. The Anticline of the Buchenstein Valley ............... 583 
EV. hens ella ATagsivies Mqeceecdue ona ac eecs tose ccusacee oper teeter 590 
V..c SettiSassvamduPralometa) oi... .d.ceones heotcneneeecaeeneee 613 

VI. Application of the Principles of Torsion in the 
Dolomites and in the Judicarian-Asta Region ...... 625 


I. InrrRopuctory REMARKS. 


Tue Sella Massive at the time when I examined it (1891- 
1893) was one of the least visited of the Dolomite-mountains. 
Its remoteness from the main tourist-routes was the chief draw- 
back to popularity. But, in 1894, a new driving-road was opened 
between Bruneck in the Puster Valley and Corvara in Enneberg 
(a village at the foot of the Groden Pass and the Sella Massive). 
A shelter-hut was also built on the mountain-terrace below the 
Boe summit, and has since been satisfactorily conducted under the 
auspices of the Bamberg section of the German and Austrian 
Alpine Club. Thus, when I revisited the country in the season of 
1898, I found that Enneberg and the Sella Massive had been 
brought well within the sphere of ordinary tourist intercourse, and 
that the physical difficulties of the long marches and ascents had 
been very materially reduced. | 

An historical epitome of the Geological Literature respecting 
the ‘Dolomites’ was given in my first paper on the subject, pub- 
lished in February 1893.’ It will be sufficient here to note briefly 
the facts and opinions arrived at by geologists previous to the 
reading of the present paper, grouping them generally according 
as they deal, on the one hand with the stratigraphical, and on the 
other hand with the tectonic side of the question. 


Stratigraphical.—The general succession of the Triassic rocks 
as laid down by Baron F. von Richthofen* for the region of the 
Dolomites is familiar to most geologists. The various members of 
the sequence occur in the following (ascending) order :— 

(A) The Lower Trias or Werfen Series, subdivided locally into Seis 
Limestone and Campil Sandstone, with characteristic fossils. 


(B) The Middle Trias or Muschelkalk Series, embracing a lower 
and more calcareous and fossiliferous horizon, and a higher and more 


1 M.M. Ogilvie, ‘Contributions to the Geology of the Wengen & St. Cassian 


Strata in Southern Tyrol,’ Quart. Journ. Geol. Soe. vol. xlix (1893) pp. 1-78. 
2 *Geognostische Beschreibung der Umgegend von Predazzo, St. Cassian ete.,’ 
Gotha, 1860. 


Vol. 55.] TORSION-STRUCIURE OF THE DOLOMITES. 562 


dolomitic horizon (the Mendola Dolomite), followed in Southern 
Tyrol by the Buchenstein banded limestones and conglomerates, 
with frequent occurrence of lavas and volcanic tuffs (especially the 
greenish pietra verde). 

(C) The succeeding horizons—named by Richthofen Wengen strata, 
Cassian strata, and Schlern Dolomite—are more particularly 
those around which, together with the next horizon in the succession— 
the Raibl strata—the stratigraphical difficulties in the Dolomites 
have grouped themselves. 

(D) The highest horizon of the Trias—namely, the Dachstein Lime- 
stone which follows—has long been quite definitely determined in 
the Dolomites. 

With regard to the group of strata (C) below the Dachstein 
horizon, it will be remembered that when I first wrote upon the 
subject of the Dolomites, the questions at issue were mainly con- 
cerning the distribution of the different rock-facies in the 
region, namely :— 

(1) Whether the massive Schlern Dolomite was the time-equivalent of 
the tufaceous shales and marls and thin-bedded limestones comprised 
as the Wengen and Cassian Series, etc. 

(2) Whether the dolomitic rock-facies had been originally developed in 
thicknesses of 2000 or 3000 feet, forming precipitous mountain-walls,,. 
and then as suddenly dwindled down to nothing amid the surround- 
ing deposits of earthy facies. 

(8) And whether, if such were the case, the ‘coral-reef’ theory ascribing 
these enormous thicknesses of rock to coralline agency accounted for 
all the peculiarities of the district. 


_ The coral-reef theory was merely suggested’ by Baron F. von 
Richthofen in 1860 as a possible explanation of the curious 
stratigraphical features then not easily paralleled ; but it entirely 
permeates the brilliant work of Mojsisovics,? and meets there with 
an elaboration of detail which would appear to carry conviction 
with it. 

Certain peculiarities, however, remained unexplained to the minds 
of many, and Baron F. von Richthofen pointed out to me how and 
where some of the main problems might best be re-investigated, 
advising, above all, a minute search for fossils in the earthy strata 
of Enneberg, etc., and a detailed mapping of the fossiliferous. 
zones round the base of a massive. This is the method which I 
have followed at every available opportunity since 1891. 

In my papers, published in 1893 & 1894, I? established the 
following conclusions respecting the question of local lithological 
facies :— 

(1) The Schlern Dolomite was originally a single sedimentary sheet 


overlying the earthy, thinly-bedded Wengen and Cassian strata 
throughout Groden, Enneberg, and Ampezzo. 


1 An account of the first enunciation of this theory by Richthofen, th 
opposition which it received at the hands of the late C. W. von Gimbel and 
Prof. Lepsius. and the strong support from E. yon Mojsisovics, has been pre- 
viously given by the present author, op. cit., Quart. Journ. Geol. Soc. vol. xlix 
(1893) pp. 4-12. 

2 «Die Dolomit-Riffe von Siid-Tirol u. Venetien,’ Vienna, 1879. 

3 Op. cit. Quart. Journ. Geol. Soc. vol. xlix, p. 47; and ‘Coral in th 
Dolomites,’ Geol. Mag. 1894, pp. 1, 49. 


Q.J.G.8. No. 219. 20 


262 MISS M. M. OGILVIE [MRS. coRDON] oN THE _—[ Aug. 1899, 


(2) It rests conformably upon successively higher and higher palzon- 
tological zones of these thinly-bedded strata, when followed from 
south and south-west to north and north-east through the heart of 
that district. 

(3) Its upper limit, with reference to the succeeding Raibl strata, varies at 
different localities ' correspondingly, but more rapidly and somewhat 
more irregularly; in no case, however, do Raibl strata repose upon 
any other horizon than Schlern Dolomite. 

(4) Fragmentary tufaceous material, associated with contemporaneous 
eruptive activity, is intermixed with all the thinly-bedded earthy 
series— Wengen, Cassian, and Raibl strata. 

(5) Interstratified with the tufaceous deposits are lenticular beds, blocks, 
and thinly-spread banks (Cipit-Kalk) of coral-growth, both in 
Cassian and Raibl strata; on the other hand, such coral-growths were 
observed to be comparatively rare in the Schlern Dolomite itself. 
This was found to be a stratified marine deposit, in which 
remains of algal, molluscan, and echinoderm life (even if so much 
altered by dolomitization as merely to deserve the name of ‘ traces’) 
prevailed far more largely than corals. 

(6) The heteropism exhibited in the lithological facies presented by the 
paleontological zones of Wengen and Cassian strata led me to the 
conclusion that an ancient geographical limiting-line (now locally 
segmented) had extended in Triassic time east and west through the 
Dolomite-region. To the south of this line the earthy Wengen and 
Cassian strata disappear, giving place to thick masses of calcareous 
rock, namely, the Marmolata-Kalk; hence I concluded that the 
Schlern Dolomite of Groden, etc. was the time-equivalent of the 
higher horizons of the’ calcareous Marmolata-facies to the south, 
while the earthy Wengen-Cassian strata represent in time the lower 
horizons of the southern caleareous series. 


Having traced segments of the old geographical limit of Cassian 
and Wengen time along the exposures of igneous and tufaceous 
rock, from Mahlknecht through Duron, Rodella, Sasso di Mezzodi, 
etc., to Col di Lana, I explained the existence of such a limit as 
the result of a downthrow to the south during the time of deposition 
of the different Middle-Triassic facies; and stated that, in my 
opinion, ‘contemporaneous faulting and volcanic action were the 
cause of mid-Triassic heteropism in South Tyrol.’? 

These conclusions show distinctly that such paleontological and 
lithological evidence as is obtainable does not support the application 
of Darwin’s theory of the origin of coral-reefs which had been 
made to this particular region of the Alps. 


Tectonic.—The brilliant researches and conclusions of Mojsi- 
sovics, Suess, Vacek, Benecke, Bittner, and others respecting the 
complicated structure and tectonic accidents of the Peri-Adriatic 
region are familiar to students of Alpine geology. So long as little 
was known of the extraordinary effects of earth-crust movement in 
mountain-ranges, it was but natural that geologists should regard 
the peculiar forms of the Dolomite-massives in the Tyrol as original 
structures. But, with the growth of our knowledge of: the compli- 
cated structures of mountain-regions during the last quarter of a 


1 §. von Wohrmann & Koken, ‘Die Fauna der Raibler Schichten vom 
Schlernplateau,’ Zeitschr. d. Deutsch. geol, Gesellsch. vol. xliv (1892) p. 167. 
? Geol. Mag. 1894, p. 10. 


Vol. 55.1] TORSION-STRUCTURE OF THE DOLOMITES. 563 


century, the subject has gradually assumed a new aspect, and a 
tendency has been developed among geologists to regard these 
strange forms as of secondary origin—the results of the partial 
denudation of a mountain-region built up of normal rock-formations, 
which had been affected by excessive crust-movement. For example, 
it will be in the recollection of some of those who attended the 
Geological Section of the British Association at Edinburgh in 1892 
that this point of view was taken by Prof. Lapworth, who, carrying 
out the principles dwelt upon in his Address,! urged, during one of 
the discussions, that the Dolomite-country was a typical region of 
eross-folding and faulting, and that its so-called reefs and other 
characteristic features were of secondary and tectonic origin due to 
Tertiary crust-movements, with which movements the injected 
bosses and sills (including even those of Predazzo) were probably 
connected. 

Passing, therefore, to the tectonic side of the Dolomite question, 
it may here be briefly indicated that the chief structural conclusions 
worked out in my previous papers were as follows :— 


(7) Some of the curious stratigraphical appearances round the base of the 
so-called ‘reefs,’ synonymous with the mountain-masses, are due to 
faults. 

(8) A large proportion of these faults have inclined fault-planes, upon 
some of which overthrust, and upon others downthrow, has taken 
place. 

(9) These inclined faults have been cut locally by subsequent transverse 
faults, causing horizontal displacement. 

(10) Igneous rocks occur as injected sheets and dykes in some of the many 
anticlinal faults. 

(11) The above-described system of overthrusting and cross-faulting in 
Enneberg and Ampezzo corresponds in all its characteristic features 
with the Judicarian-Asta system of faults demonstrated in the various 
parts of Southern Tyrol by Suess, Vacek, Benecke, Bittner, and 
Heernes. ‘The same long flexures passing locally into faults occur, 
the same types of overthrusting, and the same swinging round of the 
Judicarian dislocations into those of the Asta series.’ In fine, the 
areas mapped by the present author were characterized by a group of 
stratigraphical features in complete harmony with features previously 
identified in neighbouring areas; and these dominant stratigraphical 
features were quite independent of the Middle Triassic facies within 
region of the Dolomites. 

(12) With regard to the geological age of these disturbances, the writer 
demonstrated the broken course of one main longitudinal fault or 
flexure of Triassic age; emphasized the presence of a number of 
parallel longitudinal faults, all containing eruptive injections, and all 
giving evidence that they had been important planes of movement 
since Mesozoic times, concluding that the predominating system of 
faults identified by her with the Judicarian-Asta system generally, 
must be of Tertiary age: these ‘in some places coincided with, or 
crossed at varying angles, lines of Triassic disturbance,’ a conspicuous 
example being the famous ‘eruptive fault’ of Monzoni-Fassa 
associated with the igneous injections of the neighbourhood of 
Predazzo. 


The igneous dykes penetrate nowhere higher than Upper Triassic 
rock in the Dolomites, and even as late as 1894 I was unable 


1 Brit. Assoc. Rep. 1892 (Edinburgh) pp. 699 e¢ segq. 
202 


564 MISS M. M. OGILVIE [ MRS. GORDON | ON THE [Aug. 1899, 


to bring forward any conclusive evidence of the age of the younger 
injection-dykes in the longitudinal faults of Enneberg. The 
relationship in time of the younger injections with the younger 
system of faults was highly probable, but this did not limit the age’ 
of these injections to Tertiary time, as the crust-movements of the 
atest Alpine upheaval were already advancing through the Eastern: 
Alps in Cretaceous time. Moreover, the dykes were found to be 
cut by the transverse faults, which are the youngest faults of the 
district. All that I was then in a position to say for Enneberg 
was that ‘It would seem that the Judicarian-Asta system of faults 
followed largely ancient lines of weakness, which had been marked 
by the outbreak of lavas in Triassic time, or intrusions of porphyry 
of uncertain age.’ * 

Thus it remained to discover what was the relationship between’ 
Triassic and Tertiary movements in the areas under observation. 
Further, though overthrust-shearing might account for the lenticular 
shape of some of the mountains (as, for example, Sasso Pitschi), it 
would not altogether explain the constant recurrence of circular and’ 
elliptical mountain-shapes with precipitous walls of dolomite-rock, 
composed of younger Triassic rocks, sunk in appearance into the 
middle of swelling Alpine pasture-lands composed of older Triassic 
rocks ; nor, again, the remarkable basin-shaped or C-shaped depres-. 
sions in the very heart of the massives themselves, containing twisted 
masses of Jurassic or Cretaceous rocks in abnormal stratigraphical 
relations to the Dachstein Limestone of Upper Triassic age. 

Three years’ unabated work had only sufficed to show me that the 
coral-reef theory was wrong, and that the explanation of the 
phenomena by transverse and overthrust-faulting, so far as my 
observations disclosed, was insufficient. Clearly some greater, 
general cause lay behind all these features. I then spent two- 
years in visiting and studying as many other parts of the Alps as 
. possible, and thereupon returned to the Dolomites, to map, in 
fuller detail, the area that immediately adjoins my previously 
published map of Sett Sass and Pralongia. 


Results obtained in recent years by other inves- 
tigators.—Before entering upon the description of the district 
investigated and the new results obtained, it will be best to clear 
the ground by pointing out the present state of knowledge and 
opinion with reference to the facts and conclusions advanced in the: 
author’s previous papers, some of these conclusions having been 
strikingly corroborated by the circumstance that other observers in 
the same field have arrived at results either identical or in perfect 
agreement with them. 

In 1894, Prof. Rothpletz published his description of a com- 
plete section across the Eastern Alps.” A part of this section 


1 Op. cit. Geol. Mag. 1894, p. 58. 

* « Kin Geologischer Querschnitt durch die Ost-Alpen, nebst Anhang tuber die 
sog. Glarner Doppelfalte, Stuttgart, 1894. The present author has, in previous 
works, acknowledged her indebtedness to Prof. Rothpletz, first as a student. 
attending his lectures and afterwards in the free interchange of opinion. 


Vol. 55.] TORSLON-STRUCTURE OF THE DOLOMITES. 565 


passes through Seisser Alp and Schlern Mountain, and differs 
' greatly from the Austrian Survey-work under E. von Mojsisovics. 
One chapter is devoted to the question of the origin of Schlern 
Dolomite; and Rothpletz concludes that it is a normal marine 
deposit and no coral-growth. Further, he gives sections 
showing that he had nowhere found (as asserted by the officers 
of the Austrian Survey) that Raibl strata sometimes rest 
conformably on Cassian beds. 

In 1895, Dr. Salomon? published the results of his work on the 
Marmolata region, immediately south of the Enneberg district 
which had been part of the present author’s field of observation. 
His results show, for this region, the existence of similar phenomena, 
and lead him to corresponding conclusions. Thus, he proved that 
{1) thrust-planes occur with overthrust to the south; (2) the over- 
thrust-planes are cut by transverse faults; (3) the igneous dykes 
occasionally occur in fault-planes ; and he concluded, upon palezon- 
tological and stratigraphical grounds, that the Marmolata Limestone 
was of Wengen and Cassian age in its lower members, and in its 
higher members the equivalent of the Schlern Dolomite. But 
whereas Dr. Salomon found the overthrusting to be towards the 
south in the Marmolata, I had found it to be towards the north 
in the Durrenstein, etc., on the northern edge of the Dolomites, 
and in almost every direction within the Sella Group. 

In 1895 also, Prof. W. C. Brogger? published the results of his 
observations among the igneous rocks of the Fleims-Fassa district, 
arranging the igneous rocks in that area in the following ascend- 
ing order :— 


(1) Basic dykes and flows (augite-porphyrite, tuffs, etc.), of Middle Triassic 


ape: 

(2) More acid rocks (particularly monzonite) associated with, but younger 
than, the foregoing. 

(3) Red granite (at Predazzo) younger than 2, and probably associated with 
quartz-porphyry dykes. 

(4) The youngest eruptions of the district, represented by a series of comple- 
mentary dykes, partly of ultrabasic composition (camptonite, etc.) 
and partly of intermediate composition (liebenerite-porphyry, 
etc.). The last-named rock ‘seems to represent quite the youngest 
eruptions of the whole district.’ 


(These conclusions appear to be in full accord with the results 
obtained by the present author in Enneberg and the Groden Pass; 
where the youngest dykes belong to the last-named category, and a 
definite age can be assigned only to older basic dykes which are 
-associated with the flows and tuffs demonstrably of Middle Triassie 


e.) 
In 1897, Dr. Salomon * published a paper on the relations of the 


1 <Geologische u. palaontologische Studien tber die Marmolata,’ Palzonto- 
graphica, vol. xlii, pp. 1-210. 

metic Eruptivgesteine des Kristianiagebietes: II. Die Eruptionsfolge der 
triadischen Eruptivgesteine bei Predazzo in Siid-Tyrol,’ Kristiania, 1895. 

3 ‘Ueber Alter, Lagerungsform u. Entstehungsart d. periadriatischen gra- 
nitischkornigen Massen,’ Tscherm, Min, u. Petr. Mitth. vol. xvii, pp. 109-283. 


566 MISS M. M, OGILVIE [MRS. GoRDON] on THE [Aug. 1899, 


eranite-grained masses round the Peri-Adriatic area of subsidence, 
agreeing with Prof. Brogger that the granite- and monzonite-masses. 
and the liebenerite-dykes are younger than the Middle Triassic series ; 
and stating that, ‘in the present state of our knowledge, we cannot 
possibly say at present whether they are to be regarded as Upper 
Triassic, Jurassic, Cretaceous, or Tertiary.’ He inclines, however,. 
to the view that they are of Lower Tertiary age. 


Conclusions arrived at in the present paper.—In the 
present paper I propose to show that the results obtained during: 
my recent detailed survey of the Sella and Sett Sass district fully 
establish the following conclusions :— 


(1) Faults and overfaults are far more prevalent in the Dolomite-country 
than has hitherto been supposed. 

(2) The arrangement of these faults is typically a torsion-pheno- 
menon. 

(8) This phenomenon is the result of the superposition of a later upon an 
earlier strike of the rocks. 

(4) The later crust-movement was of Middle Tertiary age, and one with 
the movement which gave origin to the ‘ Judicarian-Asta’ phenomena, 
and more generally to the phenomena associated with the Oligocene- 
Miocene upheaval of the Alps. 

(5) The youngest dykes and granitic masses are of this age, while the 
geographical position of both is the natural effect of the crust-torsion 
itself. 

(6) The phenomenon of crust-torsion fully explains the special strati- 
graphical features of the Dolomites enumerated above, namely, the 
present isolation of the mountain-massives of dolomite-rock, the 
irregular shearing of various horizons of lower rocks around the base 
of the massives, the fanning-out of overthrust slices of the lower rocks: 
in the intervening passes and valleys between the massives, and the 
presence of ‘scoops’ of Jurassic and Cretaceous rocks within the 
massives themselves. 


Il. Tue ANTICLINE oF THE GRODEN Pass. 


Previous description of the Groéden Pass area by 
the Austrian Geological Survey.—The strata of Groden 
Pass and Sella Mountain have been described in outline in the 
Survey carried out by E. von Mojsisovics' and his colleagues. But 
as he recognizes in the Wengen and Cassian tufaceous, marly, 
and calcareous series at the base of the mountain-cliffs only the 
equivalent in time of the dolomite-rock that chiefly forms the 
cliffs, he calls the latter rock Wengen and Cassian ‘ coral-reef’ 
dolomite, and maps it as if it thinned out all round the mountain into: 
the supposed ‘ heteropic’ facies of earthy deposits (see p. 562). 

This standpoint completely differs from the present author’s, and 
it would only obscure this paper to draw repeated comparisons 
between the observations published in Mojsisovics’s ‘ Dolomit-Riffe’ 
in 1879, and those now made by me in very much greater detail. 


' «Die Dolomit-Riffe von Siid-Tirol u. Venetien,’ 1879, chap. viii, p. 227. 


Vol. 55. | TORSION-STRUCTURE OF THE DOLOMITES. 567 


Any comparison which seems desirable to the reader can be made 
independently ; more especially would I call attention to several 
excellent photographs in the work just quoted. 


General form of the Groden Pass Anticline on the 
west side of the Pass.—Approaching the Pass from the Groden' 
Valley, the footpath for the ascent is reached at Plon (see General 
Map, Pl. XL*). The rocks in the stream beside the Plon Inn are 
fossiliferous Bellerophon-limestone strata. These Permian rocks are 
succeeded by a disturbed succession of Lower Triassic (Seis and Campil 
strata) and Muschelkalk horizons. The whole series represents an 
anticlinal form which we may term the Groden Pass Anticline. 

The anticline is here greatly contorted, and split into two un- 
symmetrical halves by a longitudinal fault directed west-south-west 
and east-north-east, and to this reference will be made as the 
Plon Fault. Minor transverse dislocations cross this longitudinal 
fault: one of these is well exposed where it penetrates Seis Lime- 
stone near a lateral waterfall, the limestone standing vertically. 

The strike of the rocks in the northern fault-block of the anticline 
veers round from a north-westcrly and south-easterly direction to 
west-south-west and east-north-east; the general dip is northward 
throughout, although the angle varies very frequently. The strike 
veers round similarly in the southern fault-block, where the dip, 
in spite of many small faults, holds southward. The crags and 
steep pastures of Pitzculatsch Hill represent the southern fault- 
block. They may be most conveniently examined by taking the path 
from Plon towards the Sella Pass, and diverging from it towards 
the numerous exposures on the hillside. 


The Pitzculatsch Fault-dyke—wWhen a height of about 
1800 metres is reached on the path, a steep gully will be found 
running up the hill, but it is practically hidden from the pathway 
by fir and brushwood. A dyke of igneous rock occupies the gully, 
and follows the course of a vertical fault east-north-eastward to the 
Groden Pass. Muschelkalk strata, more particularly the Mendola 
Dolomite or upper horizons, are faulted on the north side of the 
fault against Wengen strata, and on the south side towards Sella 
(fig. 1, p. 568). 


Origin of the so-called ‘Buchenstein conglomeratic 
tuff’ as a shear-and-contact breccia.—the strata on both 
sides show marked effects both of shear-slip and of contact-alteration. 
The rocks exhibit in a remarkable degree the result of mutual 
metamorphism of the intrusive and stratified masses. I observed 
here quite clearly that the so-called ‘ Buchenstein conglomeratic tuff’ 
or ‘ Buchenstein agglomerate’ has its origin as sheared and altered 


1 The redrawing of the author’s coloured map and original illustrations for 
reproduction in black and white was carried out by Miss H. M. R. Wood and 
Mr. F. Raw in the Research Section of the Geological Department of Mason 
University College, Birmingham, with the result that few practical detail 
have been lost, despite considerable reduction in size. 


Fig. 1.—WSection through the anticlinal buckle of the Groéden Pass 


; 1 
(western portion) on the scale of 3990 


Gardenazza Sella 
Group. Group. 
R TPL. : 
S 
~< aS Foy | Xen NON 
wee th ea EF Porph. 
WS FandtPophayp Meio, Wi Perm. 1 Mn Ge 
SD=Schlern Dolomite. Perm. = Permian. 
C=Cassian strata. Agg=So-called ‘Buchenstein ag- 
We= Wengen strata. glomerate,’ author’s ‘shear- 
Bce=Buchenstein bedded rocks. and-contact breccia.’ 
Mk=Muschelkalk (Mendola Dolo- FP= Fault-porphyrite. 
mite). TPl=Thrust-plane. 
L.M=Lower Muschelkalk. A= Pitzeulatsch Fault. 
Wf= Werfen strata. B=Vallbach Fault. 


Fig. 2.—Fold-form, west side of the Groden Pass Antacline. 


Fig. 3.—Nomenclature of the fold-form, west side of the Gréden 
Pass Anticline. 


Vol. 55. | THE TORSION-STRUCTURE OF THE DOLOMITES. 569 


Mendola Dolomite. Structurally, it is a ‘ crush-breccia’ (Bonney) 
dragged along with the intrusive dyke-material of the fault, and 
practically defining the outcrop of the fault-zone. 

Brightly-banded and black, splintery, shaly masses are present 
on the south side of the fault-dyke, passing into greenish and 
whitish, crumbling ‘ paper-shales’ in actual contact with the intru- 
sive rock. This soft rock-material is a baked and altered repre- 
sentative of a thinly-bedded series of bituminous limestones, in 
which, at no very great distance, remains of the local Wengen flora 
and fauna are to be found. 

A strip of characteristic light-grey limestone with siliceous 
nodules* intervenes at another part of the fault between the dyke 
and the wide outcrop of crumpled strata on the southern slope of the 
hill. The latter are the lower or ‘ Wengen’ group of the Wengen- 
Cassian Series, and they contain abundant plant-remains, together 
with Halobia Lommeli, Posidonomya wengensis, and some badly- 
preserved Ammonites. The fossils show various degrees of com- 
pression and distortion. Tufaceous grits, black earthy tuffs, and 
thin lavas are interbedded with the fossiliferous strata. 

Considerable patches of Wengen rocks occur caught in with the 
dyke-rock and lying in its midst, within the fault-zone. The 
results of contact-alteration and fault-shear are evidenced in the 
finest detail in those carried wedges. One fairly large wedge is 
represented on the map, situated where the Pitzculatsch fault-dyke 
widens out on the middle levels between Plon and the Pass height. 

The fault-zone may be said to fork in two directions here, 
one branch twisting sharply north-north-eastward, in the direction 
of Spitz Kofl, the other branch continuing the main longitudinal 
direction east-north-eastward. The twisted branch is marked by the 
presence of sheared and brecciated rock chiefly composed of rock- 
masses and fragments belonging to the higher Muschelkalk horizon. 
This‘ fault-rock’ is brought against the various horizons of the 
Werfen and Lower Muschelkalk strata exposed in the Plon anti- 
cline on the west, and against the main fault-dyke and patches of 
Wengen strata on the east. The direct branch is marked by the 
presence of the porphyrite-dyke, which is here brought into contact 
on both sides with disturbed and altered Wengen strata. 


The Vallbach fault-dykes and sills.—A glance at the 
map (Pl. XL) will show that other dykes branch out from this 
median area on the western slope of the Pass. These are dykes 
extending in an east-south-easterly to west-north-westerly direction 
towards Wolkenstein. Thick masses of the characteristic fault- 
breccias and altered tuff-rocks are present between the dykes, as 
well as unaltered but highly-tilted remnants of Lower Muschelkalk, 


1 The ‘siliceous limestone’ belongs to a thin group of strata which marks 
in this district a limiting horizon between the ‘Mendola Dolomite’ and the 
Wengen Series. It represents the ‘ Buchenstein’ horizon proper, and has in 
the more recent publications been referred to the Upper Muschelkalk. 


oO 


70 MISS M. M. OGILVIE [MRS. GORDON] oN THE  [Aug. 1899, 


Mendola Dolomite, and of the next higher or ‘ Buchenstein’ (see foot- 
note, p. 569) horizon of limestones. An important dyke is exposed 
on the northern slopes of the Vallbach hill and in the bed of the 
stream. It marks a fault-line which penetrates the northern half 
of the anticline and lets down the Wengen strata to the north, just 
as the fault of the Pitzculatsch hill cuts the southern half and effects 
the downthrow of the Wengen strata tothe south. These two faults 
are distinguished as A & B in the section (fig. 1, p. 568), and may 
be conveniently termed the Pitzculatsch and Vallbach Faults 
respectively. 

Another intrusion on the summit and southern slope of the Vallbach 
hill presents a connected ‘ torsion-network’ (Lossen) of dykes 
and sills, threaded through the Muschelkalk and Lower Trias in 
fault-planes inclined northward at various angles, and sometimes 
vertical (fig. 1, p. 568). The Vallbach intrusions occur in con- 
nexion with a series of faults that penetrate the northern wing of 
the anticline, and effect torsion of its strike round the dolomite- 
cliffs north of the Pass. 1 followed this network in all its detail, 
ascending the precipitous rocks facing the church of Sta. Maria, 
and discovering there very good examples of shear-and-contact 
metamorphism in horizons of Muschelkalk; then tracing the various 
threads round the slopes facing Plon and along the ridge of the 
Vallbach hill between the Vall and Frea streams. Altered and 
brecciated Muschelkalk-rocks in the form of the so-called ‘ Buchen- 
stein agglomerate’ accompany everywhere the igneous intrusions. 
It is quite impossible to show all the details in the map (Pl. XL), 
yet it is hoped that sufficient detail is there given to prove that 
the injection of igneous material has taken place in 
a fault-network associated with an actual twist in 
the strike of the rocks. | 

First in importance in this map I rank the demonstration that 
it gives of the intrusive rock running into and along the sub- 
ordinate oblique and transverse faults on the Groden 
Pass slopes, as well as into and along the main longitudinal, 
inclined planes of fault. The intrusive rock extends for a 
considerable distance in a north-and-south transverse fault between 
Wolkenstein and the Pass. This may be termed the Wolken- 
stein Fault, and it is one of the chief transverse faults of the 
district. 

Fresh specimens of the intruded rock may be described as some- 
times typical porphyrite of the district with augitic crystals, some- 
times a plagioclase-porphyrite ; amygdaloidal inclusions are frequent. 
What haye hitherto been grouped as ‘ Buchenstein tuffs,’ and attri- 
buted along with the augite-porphyrite to Middle Triassic age, are 
fault-rocks representing a compounded mass of fault-dyke material 
and fragments of the various stratified rocks affected in the planes 
of crust-movement. Slickenside appearances are very prevalent, 
while cleavage is another marked feature, extremely variable in the 
rocks nearest the sills and dykes. 

The ‘ fold-form’ of the western slope of the Gréden Pass (figs. 2 & 3, 


Vol §5.] TORSION-STRUCTURE OF THE DOLOMITES. 571 


p. 568) may be generally described as a distorted anticline with 
S-curvatures northward and southward, bent into the form of 
‘knee-bends’ (Mojsisovics) and penetrated by injected igneous rock 
in the two opposite areas of the ‘ middle limbs’ (Heim). 


Structure of the central part of the Groéden Pass.— 
The outcrops of the Pitzculatsch, Plon, and Vallbach Faults converge 
towards the height of the Gréden Pass. The strata on the Pass- 
ridge are steeply contorted, bedded tuffs and lavas, tufaceous grits, 
marls and shales composing the Wengen Series. Numerous dis- 
locations penetrate these soft rocks. The major dislocation that 
breaks the anticline is indicated by a line of blocks crossing the Pass- 
ridge continuously from the convergence-area of intrusive rock on 
the western side to an area on the eastern side where intrusive rock 
reappears. It then proceeds in a west-south-westerly and east- 
north-easterly direction towards Sass Songe, continuing therefore 
the direction of the Pitzculatsch Fault. It forms, however, the 
northern limit of the anticline on the eastern slopes of the Pass, 
_ similar in position to the Vallbach Fault on the western slopes, 
and, like it, is a normal fault with downthrow to the north, that is,. 
towards the Tschampatsch and Sass Songe cliffs. 

Another fault branches from the same high level on the eastern 
slopes, and continues the general east-and-west (slightly west-north- 
west to east-south-east) direction of the Vallbach Fault. But 
it corresponds with the Pitzculatsch Fault, in so far as it forms 
the southern limit of the anticline on the eastern side of the Pass. 
The southern fault is here distinctly reversed, with overthrust to the 
south (fig. 4, p. 572). 

The combination of a normal and a reversed fault hading in the 
same direction is one which I have found to be a characteristic 
feature in the stratigraphy of the district, and its effect is to leave 
the outcrops of the downthrown strata on either side of the neutral- 
izing faults practically at one and the same level (fig. 5, p. 572). 


The ‘Ruon’ Rock.—About midway down the eastern slopes of 
the Pass near Ruon a prominent mass of Mendola Dolomite com- 
mands attention. This is a thick wedge caught in the midst 
of a fault-net of injected igneous rock, and the rock has been 
cleaved, sheared, and mutilated to such a degree that it is difficult 
to define any limit between the Mendola Dolomite and its burnt and 
sheared representative, the so-called ‘ Buchenstein agglomerate.’ 
At the same time, small fragments of so-called ‘ Buchenstein banded 
shales and limestones,’ representing, on the paleontological evidence, 
merely altered Wengen calcareous bands, are caught up in the shear- 
planes. One larger unaltered wedge of Wengen strata fills in the 
chief rupture-fissure on the eastern side of a transverse fault-dyke. 
This will be referred to later as the Ruon Dyke. 

The whole complex is only a more striking case of the same 
general phenomena of dyke-injection associated with fault-shearing 
as those that I have described at the forking of the Pitzculatsch 


Fig. 4.—Section through the anticlinal buckle of the Gréden Pass 
(eastern portion) on the scale of a 


Tschampatsch Group, 
Gardenazza Massive. 


N. 


B/S 
2. kB IT Chapel Inn. 


Se 
SS a 

ma S 

* 


VAT AIA 


(fms 
4A. 


SEZEZZ J 
ZGLLZGE V2 Colfosco. 
CLOLELEA a y 
EZZ4 222; JH: - é 
CLEZGzEZ AT BE 

Zt 

Z 


SN 


D.K=Dachstein Limestone. 
R=Raibl marls & dolomitiec flag- 
stones. 

S.D=Schlern Dolomite. 

C=Cassian Marls and -Cipit Lime- 
stone-beds. 

Wg=Wengen earthy and tufaceous 
strata, with interbanded lime- 
stones. 

Bce=Buchenstein flagstones, shales, 
banded and nodular lime- 
stones. 


Sella Massive. 


2 


Mk=Muschelkalk: thickly - bedded 
limestone, partly dolomitic, 
poor in fossils. 

Lm=Lower Muschelkalk ; thinly- 

bedded fossiliferous limestones. 

Agg=Shear-and-contact breccia. 

F.P = Fault-porphyrite. 


T.Pl=Peripheral overthrust-plane of 
the Sella Massive. 
A=Pitzculatsch Fault. 
B=Vallbach Fault. 


Fig. 5.—Fold-form, east side of the Groéden Pass Anticline. 
5. 


W. Hemp 


n=Normal fault ; r= Reversed fault. 


Fig. 6.—Nomenclature of the fold-form, east side of the Gréden Pass 
Anticline. . 


5. 


Vol. 55.] THE TORSION-STRUCIURE OF THE DOLOMITES. 573 


Fault on the western slopes of the Groden Pass. The transverse 
dykes in both cases mark a strongly-twisted branch fault, run- 
ning in a northerly, north-north-westerly, or north-north-easterly 
direction across the anticline. The twisted faults probably served 
to relieve the tension in areas where the strike-faults were tending 
to converge and even to intercross. 

The distinctly ‘ knee-bent’ shape of the Groden Pass Anticline 
on the eastern slope is shown in fig. 6, p. 572. The northern wing 
has been overthrust south-south-eastward upon the ‘ reversed’ fault- 
plane, and intrusive rocks have been injected not only into the 
normal and reversed limiting-faults, but also into the associated 
transverse and oblique dislocations. 


The’ Colfosco section of the Groden Pass Anticline.— 
The Colfosco (Kollfuschg) portion of the Gréden Pass Anticline is 
also limited to the ‘ knee-bent’ strata of the northern wing, the fulk 
form of the anticline not appearing until the valley-level is reached 
below the hamlet of Pescosta. 

The steep pastoral hill-ground between the hamlets of Colfosco 
and the cliffs of Tschampatsch and Sass Songe is composed of the 
lowest Wengen horizons, Upper and Lower Muschelkalk, Campil 
and Seis strata. The various horizons are met as one descends to 
Pescosta, the margin of outcrop representing the southern fault of 
the ‘knee-bend,”’ The Mendola Dolomite is greatly cut up by dykes, 
whose direct connexion with the fault-sill B can be actually seen 
in tracing them both eastward to the stream-cutting above Colfosco. 
Contact-breccia again marks the contact-zone of the sill with the 
Mendola Dolomite, and patches of recognizable Wengen strata are 
found amid the sheared series between the fault-planes. 

The Wengen strata north of the fault B are perpendicular, 
and highly altered near the intrusive rock. They form a contorted 
fragment, cut off against Cassian strata and Schlern Dolomite to the 
north by another normal fault hading northward. 


Diagonal faults of the east side of the Groden Pass.— 
The Pass segment is separated from the Enneberg Valley segment 
by an important diagonal fault passing from the west side of Sass 
Songe (Sett Sossander) in a north-north-westerly to south-south- 
easterly direction through Pescosta to Corvara. The fault-fissure 
is occupied by a thick mass of intrusive rock, the chief outcrop 
of which crosses eastward from the Pescosta slopes to those of 
Langs-da-Fiir between Corvara and St. Cassian. But dyke-threads 
may be said to radiate from the Pescosta centre in all directions. 
The chief threads are those which run westward into the Pass fault,, 
and southward and south-south-eastward towards Corvara, Artara, 
and Campolungo. A branch of the southerly fault twists south- 
south-westward at the bend of the Rudort stream and continues as 
the chief fault east of Sella, with a westerly downthrow towards that 
mountain. Another branch continues the north-north-westerly to 
south-south-easterly direction of the Pescosta-Corvara Fault, has an 


574 MISS M. M. OGILVIE [MRS. GORDON] ON THE [ Aug. 1899, 


easterly downthrow, and crosses between Cherz Hill and Prilongia 
into the Buchenstein Valley. 

The diagonal fault of Pescosta-Corvara is parallel with another 
higher up the eastern slopes of the Groden Pass, which crosses from 
the Tschampatsch dolomite-cliffs and through the Ruon fault- 
wedge to Crap de Sella, Its downthrow is also easterly, and the 
double throw of the Pescosta and the Ruon diagonal faults 
explains why Sass Songe is visibly more deeply depressed than the 
Tschampatsch, and much more than the Spitz Kofl group which 
occupies the head of the Pass. 

The throw of the faults is increasing even at the present time. 
The weight of the Sass Songe dolomite-cliffs is continuously pressing 
forward and downward on the more yielding rocks of the anticline, 
separated from Sass Songe by longitudinal dislocation. Slipped rock 
from above fills in the transverse rupture between the Pescosta fault- 
dyke and the valley-segment of the anticline, just as Wengen rocks 
have filled the analogous transverse rupture next the fault-dyke at 
the higher (Ruon) slopes of the Pass (see p. 571). 


Relations of the strata described to those of the 
massives north and south of the Groden Pass.— 
(a) Although the downthrow of the dolomite in the cliffs north 
of the Groden Pass is greatest at Sass Songe, the whole range 
of dolomite in the cliffs which form the face of the Gardenazza 
Massive is thrown down, relatively to the crumpled exposures of 
Wengen strata that accompany the northern lmiting-fault of the 
Groden Pass anticline. A normal fault (see figs. 1 & 4, pp. 568 & 
572) sweeps in a curving direction over the Pass always near the 
base of the northern cliffs, and cuts off Wengen strata against 
different horizons of Cassian strata and Schlern Dolomite. It may 
be followed westward across the Langenthal towards the Ruine- 
Wolkenstein cliffs. 

(3) The relation of the Gréden Pass Anticline to the dolomite- 
cliffs of the Sella Massive on the south of the Pass is so far similar. 
Faults have passed through the steep southern wing of the anticline, 
letting down the Sella region relatively to the Groden Pass areas. 
But an overthrust has taken place northward from the Sella region 
on a reversed fault-plane, inclined away from the Pass and into the 
heart of the Sella Massive. The Sella overthrust is exposed in 
the Cassian or Schlern Dolomite horizons ; while the Pass overthrust 
to the south-south-east is exposed chiefly in the Muschelkalk and 
Wengen horizons, and is accompanied by ramifying threads of 
intrusive dyke- and sill-rocks (figs. 4—6, p. 572). 

. The Sella overthrust will be dealt with later (p. 593), but almost 
any photographic panorama of the overthrust as shown on the eastern 
side of the Groden Pass will serve to exhibit the shear-zone, where 
fragments of Cassian strata dipping outward are pushed above an 
irregular thickness of Schlern Dolomite dipping steeply inward. 
The reading given to these appearances in Mojsisovics’s ‘ Dolomit- 
Riffe? was that of coral-built cliffs of calcareo-dolomitic rock 


Vala 55.4 °. TORSION-STRUCTURE OF THE DOLOMITES. 575 


thinning out into contemporaneous earthy deposits of Wengen 
age around the steep outer slopes of the ‘ reef.’ 


Cleavage-phenomena of the Pass.—The phenomena of 
cleavage are similar in the dolomite-cliffs on both sides of the Groden 
Pass. Great cleavage-slabs of Schlern-Dolomite rock face west- 
north-westward with high inclination, the direction of strongest 
cleavage being north-north-easterly and south-south-westerly in 
the areas adjoining the Pass. In the north-eastern corner of the 
Sella Massive, however, the cleavage-planes are vertical and run 
almost due north and south. 

A second set of cleavage-planes, also well developed although less 
assertive to the eye, cut the first set obliquely in a north-north- 
westerly and south-south-easterly direction, and are more constant in 
direction throughout the massives than the north-north-easterly and 
south-south-westerly planes (see fig. 21, p. 614). 

These two series of cleavage-planes are also clearly developed in 
many of the harder stratified rocks comprised within the Gréden 
Pass anticline, but are scarcely decipherable as such in the softer, 
strongly-crumpled rocks. In the twisted wedges of Muschelkalk, 
I frequently distinguished east-and-west and east-north-east and 
west-south-west planes of cleavage. 

The intercrossing in the directions of cleavages is an observation 
which I value as one in complete harmony with the intercrossing in 
the direction of the main faults over the Pass. 


Diagonal disposition of the Dolomite Massives with 
respect to the Gréden Pass Anticline.—The imposing 
mountain-block of the Lang Kofl Massive rises west of the Sella 
Massive, separated from it only by the Sella Pass, and may be said 
to face the Gréden Pass on the south-west. The present author’s 
familiarity with Pitzculatsch Hill (see p. 567) and the Sella Pass 
enable her to give some indication of the probable connexion 
between Lang Kofl and the Dolomite-mountains facing the Gréden 
Pass on the north-east. 

The neighbouring areas are separated by the Wolkenstem cross- 
fault (see p. 570). The structural details differ on the two sides 
of the cross-fault, although the main directions of folding are 
retained. The Pitzculatsch strike-fault can be traced quite well across 
the Sella Pass slopes to the north or Groden side of Lang Kofl. There 
it limits the now widened anticline, exposed on the Mont de Sora 
slopes, against the younger strata that compose the cliffs of Lang Kofi, 
the fault being accompanied throughout by intrusive porphyrite and 
an altered contact-zone of Muschelkalk and Wengen fault-rock. 

The chief general feature to be observed is that the downthrow 
to the south of the fault is distinctly greater at Lang Kofl than at 
Sella; the fault is, just as at Pitzculatsch, a normal fault, inclined 
southward towards the mountain. Reversed faults, likewise hading 
southward, occur on the Mont de Sora slopes and in the Gréden 
Valley, so far neutralizing the effect of the Lang Kofl normal fault. 


576 MISS M. M. OGILVIE [MRs. GoRDON] on THE [Aug. 1899, 


These relations at Lang Kofl are precisely analogous to the relations 
observed in detail, as existing between the Enneberg Valley segment 
and Sass Songe, and the analogy is presented in the case of 
Dolomite-mountains situated at diagonally opposite 
ends of the Groden Pass fault-system (see fig. 7, p. 578). 


REsULTs. 


(A) Facts and Deductions confirmatory of the Results of 
previous Researches. 


In summarizing the foregoing description of the geology of the 
Groden Pass and its neighbourhood, the more general features will 
first be noted, in which the stratigraphy of the Pass bears out the 
result of recent researches in the Dolomites (p. 564), more widely 
considered, in the Peri-Adriatic area of the Alps. 


(1) Combination of reversed and normal faults.—The 
fault-system of the Groden Pass has been found to comprise faults 
inclined at various angles to the horizon as well as vertical 
faults. Some of the inclined fault-planes are typical planes of over- 
thrust... The author would specially note the combination of the 
reversed and normal faults in two oppositely-inclined fault-groups, 
passing through the two opposite anticlinal wing-folds that have 
been overcast southward and northward. The oppositely-inclined 
planes of the Grdden Pass faults, if continued upward, would 
therefore meet each other as well as the vertical planes. The area 
is comparatively small, hence very involved stratigraphical relations. 
must have ensued between the dovetailed parts of fault-blocks. 


(2) Virgation of fault-lines.—The surface-outcrops of the 
faults diverge from the Pass height outward on both the western 
and eastern slopes. A divergent arrangement of fault-lines has been 
termed a ‘virgating system’ by American geologists, and a ‘fan- 
shaped fault-bundle’ by Austrian geologists. It is in association 
with the central convergence of the eastern and western fault- 
bundles that the main faults of the Groden Pass anticline (namely, the 
Pitzculatsch-Colfosco Fault, and the Vallbach-Corvara Fault) have 
their throw reversed on the opposite sides of the Pass. 

The faults may be conveniently distinguished, according to their 
geographical direction, as:—(a) Longitudinal or strike-faults, 
directed east and west, east-north-east and west-south-west, and 
east-south-east and west-north-west; (6) Diagonal or oblique 
faults, directed north-north-west and south-south-east, north- 
north-east and south-south-west, north-west and south-east, and 
north-east and south-west; (c) Transverse faults, directed 
north and south, or nearly so. 

It must, however, be understood clearly that such grouping is 
arbitrary, since longitudinal faults give off branches in oblique or 
transverse directions, and fault-planes may at one part of thei: 


Vol. 55.] TORSION-STRUCTURE OF THE DOLOMITES. 577 


force cross the strike, and at another part curve into the direction 
of strike. In short, the fault-system is pre-eminently a fault- 
network. Rapid variation in the throw of the fault is a marked 
feature, and is associated with the frequent branching of faults. 

Similar features of overthrusting, rapid variation in the throw of 
faults and in the precise angle of inclination of the fault-planes, 
branching and curving of faults, have been demonstrated by the Aus- 
trian geologists to be characteristic of the Judicarian-Asta system * 
(cf. Suess) as presented in the Peri-Adriatic region of the Alps. 


(B) New Facts and Deductions respecting the Geology of 
the Rocks of the Groden Pass. 


(1) The dyke-and-sill phenomena.—Evidences in the field 
and the authors map and sections afford proof of dyke-and-sill 
injections as an igneous network in the greater number of the 
fault-planes of the Grdden Pass, not only in the longitudinal or 
strike-faults,” but also inthe diagonal and transverse faults. Evi- 
dence is everywhere to be obtained that the fault-shearing must 
have taken place while the igneous material was still a magma, and 
could solidify round carried wedges, torn blocks, and the finest 
fragments of faulted and invaded stratified rock. These shear- 
and-contact breccias are typical ‘ fault-rock’; they have been 
grouped hitherto by all observers as ‘ Buchenstein conglomerates 
and tuffs,’ and referred to the Middle Triassic period as a distinct 
_ stratigraphical horizon. | 

The present author’s observations go to show that the injection 
of the dykes and sills into fault-planes was associated with the origin 
of the coarse shear-and-contact breccias, and took place in the last 
epoch of intense crust-movements in the Groden Pass neighbourhood. 
The development of the fault-system of the Groden Pass and Enne- 
berg generally was demonstrated in my previous papers to have 
been the Tertiary epoch of Alpine upheaval; therefore the date of 
origin of the so-called ‘ conglomeratic tuff’ or ‘agglomerate’ is not 
Middle Triassic, but Tertiary. At the same time, there are true 
lava-flows interbedded with the lower horizons of the Wengen- 
Cassian Series, although of no great thickness. These cannot be 
regarded as a determining factor in the subsequent crumpling, 
shearing, and faulting of that soft and yielding series between the 
Mendola Dolomite and the Schlern Dolomite of this region. 


1 The writer drew attention to this feature in a previous paper, when de- 
scribing the analogy of the fault-systems of Enneberg with the Judicarian and 
Asta systems of faults, demonstrated by the Austrian geologists in the Peri- 
Adriatic region. ‘ No hard-and-fast distinction can be drawn between these 
systems; they pass into one another and form one complicated system of 
movements, which may be proved even in the small district of Enneberg to 
have affected the positions of both Triassic and Mesozoic rocks,’ and therefore 
to be of Tertiary age (‘Coral in the Dolomites,’ Geol. Mag. 1894, p. 55} 

2 This was my opinion before carrying out the additional research embodied 
in the present paper. 


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Vol. 55. | THE TORSION-STRUCTURE OF THE DOLOMITES. 579 


(2) The torsion-phenomena.—Another new and far more 
striking feature in the geology of the Pass is the abundant evidence 
that the most conspicuous crust-movement has been one of crust- 
torsion.’ My own observations illustrative of torsion at the Groden 
Pass may now be classified, reference being understood to the 
scheme, map, and sections :— 


1. Torsion of the strike of the strata.—tThe strike of the rocks in the 
various fault-blocks of the anticline veers round from longitudinal to oblique 
directions. 

2. Distortion of the anticline.—The anticlinal ‘buckle’ (Lapworth) 
is asymmetric, divided into two unequal wings by the Plon fault. Both wings 
are well exposed on the western slope, where they form together an anticlinal 
fan of fault-blocks, expanding broadly in the Groden Valley. On the eastern 
slope, the northern wing is well exposed on the Pass, but vanishes below Varda 
in the Enneberg Valley. While the southern wing is represented on the Pass 
only by the higher horizons of strata, it is fully exposed on the Langs-da-fir hill 
above the Valley. The anticline, therefore, shows considerable variation within 
narrow spacial limits. 

What can be actually seen in the Pass structure is a number of separate 
fault-blocks, twisted obliquely away from a central convergent area; and the 
wider fault-gaps (and many of the narrower) filled up by intrusive rocks and 
fault-breccias. What may be deduced from the Pass structure is that if the 
intrusive rocks could be melted away, and the fault-blocks of stratified rock 
could be pulled back into line one with another on the opposite slopes of the 
Pass, the form obtained would be that of an anticlinal fold, the axis of which 
runs centrally along the Pass in the direction of its length, or, in other words, 
traverses the Pass in its meridional direction. 

3. Opposite fold-ares curving away one from another.—The 
distortion of the anticline in its several parts is such that no two sections 
through it show the same relations (compare figs. 1 & 4, pp. 568 & 572). 

The northern wing curves from west-north-west round a southern arc to east- 
north-east, and has been overcast southward into the form of a knee-bend with 
overthrusts at different parts towards the south-south-west and south-south- 
east ; normal faults curved in the same sense as the reversed faults have thrown 
down the strata to the north towards the Dolomite-cliffs of Spitz Kofl and 
Tschampatsch. 

The southern wing curves from west-south-west round a northern arc to east- 
south-east, and is cut by the Pitzculatsch Fault. The adjoining cliffs of Sella 
exhibit a back-fold curved in the same sense, but rather more south-west and 
south-east. An overthrust-plane cuts this back-fold, the overthrust taking place 
towards the north-west, north-north—west, north-north-east and north-east. 
This is, therefore, a return overthrust to northward, compensating the overthrust 
to southward in the northern wing of the anticline. 


1 The crust-movements concerned in bringing about the present structure 
of the Groden Pass and the region of which it forms a part, embrace not only 
those of folding, faulting, overfolding, overthrusting, etc., as usually under- 
stood, but in addition, and even more conspicuously, those which are commonly 
grouped under the head of torsion. 

Those geologists who are familiar, on the one hand, with the advances made 
during the last quarter of a century in knowledge and in speculation respecting 
crust-deformation, by means of folding and faulting, normal or overthrust in 
effect, and parallel, orthogonal, or oblique in direction; and, on the other 
hand, with the remarkable torsioval results worked out by Daubrée in the 
laboratory, and by Lossen and others in the field, will have no difficulty in 
recognizing for themselves what tectonic principles and resulis are new in the 
present paper, and what have been derived from, or anticipated by, the work 
and deductions of others. As respects the terminology employed, reference 
may be made to the works of Heim, de Margerie, Suess, Bertrand, Lapworth, 
Peach & Horne, Daubrée, Lossen, etc. 

2P2 


080 MISS M. M. OGILVIE [MRS. GORDON] oN THE [ Aug. 1899, 

4, Partial intersection of the opposite fold-ares.—An area of 
curve-intersection of the opposite wings is present, which fairly corresponds with 
the central area of the Pass, and the upper part of the eastern slopes. The 
southern wing cuts off the exposure of part of the southern are 
of the northern wing. Presented graphically, the fault-figure of inter- 
section is like the figure 8 laid lengthways across the central area of the 
Pass, while the virgating faults branch outward from the two ends of the figure. 
As a matter of fact, the area of fold-intersection is marked on the ground by 
strongly-contorted rocks, by block-structure, by convergence of the ramifying 
threads of intrusive rock, and by frequently twisted cleavage—a combination of 
features sufficiently indicative of ‘interference’ crust-strains. 

5. Cross-folding in its relation to torsion-forces.— Regarded 
from this central intersecting area, the strike of the radiating fore-folds and 
back-folds is directed to four points of the compass :—west-north-west, west- 
south-west, east-north-east, and east-south-east ; and as the strike of a fold is 
rectangular to the forces producing it, we have to distinguish four directions 
from which forces were acting :—south-south-west, north-north-east, north- 
north-west, and south-south-east. They may be tabulated as follows :— 


West side (northern wing), strike Forces from  north-north-east 


west-north-west and east-south-east. 


East side (southern wing), strike 


west-north-west and east-south-east. 


East side (northern wing), strike 


west-south-west and east-north-east. 


and south-south-west. 
Forces from  north-north-east 
and south-south-west. 


Forces from  north-north-west 
and south-south-east. 


Forees from north-north-west 


West side (southern wing), strike 
and south-south-east. 


west-south-west and east-north-east. 


As the axis of the Gréden Pass Anticline itself lies slightly west-south-west 
and east-north-east, the forces from north-north-west and south-south-east 
have been stronger here than those from north-north-east and south-south-west. 
The phenomena of the converse curves of the opposite folds, the convergence 
of the anticlinal fault-blocks towards the median area of the Pass, and the 
divergence of the fault-blocks outward into more and more oblique positions, 
indicate that the forces did not act in straight lines across the 
area, but in some form of curves round the area, after the 
manner of force-couples. Clearly, also, the relative action of the forces 
must have been inward in the median area where the maximum compression 
is presented, and outward on the lower slopes where virgation is presented. 

The following problem may be constructed in order to elucidate the probable 
action of the forces as indicated by the author’s observations. 

{magine an almost straight line to be drawn across the Pass nearly east. and 
west from Pescosta to Plon. Bisect this line by another at right angles. These 
divide the region roughly into four parts or quarters, which may berepresented 
by A, B, C, & D in the accompanying diagram (fig. 8, p. 581). Let C & D be 
pushed northward, A & B be pushed southward, so as to form an anticline in the 
meridional direction. At the same time, or subsequently, imagine a motion of 
the nature of a twist to be given to each of these quarters: A & C to be moved 
counter-clockwise, B & D clockwise. The effect will be, therefore, as if every 
part within each quarter had received a combination of a forward motion and 
a twist; the resultant motion will be of the nature of a spiral for each quarter 
(epitrochoid). 

Additional complications are indicated, such as a tilting of the southern 
quarters D & ©, D rising and C being depressed, the raised portion D being 
pushed so far above A in the central area. The chief fact, however, is that 
the phenomena of the Gréden Pass indicate the combined action of a 
push and a twist—crust-compression and crust-torsion—resulting in con- 
tending spiral whirls. 

We have, as it were, two dissimilar sets of force-couples acting on the Pass 
anticline, the more powerful set being north-north-westand south-south-east, and 
causing counter-clockwise torsion, the subsidiary set being north-north-east and 
suoth-south-west, and causing clockwise torsion. Consequently, there are two 


Viol. 55.) TORSION-SIRUCIURE OF THE DOLOMITES. 581 


intercrossing torsion-strikes, a principal strike west-south-west and east-north- 
east, and a subsidiary strike west-north-west and east-south-east. 

Such contending whirls of the forces seem to me to explain all the observed 
data—not only the phe- 
nomenon of an inner 
or median area of in- 
tertwining, correlated 
with lateral (east-and- 
west) outer areas of 
virgation, but also the 
phenomenon of asso- 
ciated longitudinal 
and diagonal buckling : 
since the resultants of 
the inner force-compo- 
nents pushing obliquely 
one towards another 
are the stronger result- 
ants, and are those 
which would form 
curved longitudinal 
buckles ; while the re- 
sultants of the outer 
force-components push- 
ing obliquely away one 
from another are the weaker, and are those which would form curved diagonal 
buckles. The latter are, in this area, distinctly subordinate to the longitudinal 
anticlinal buckles in size, but are almost equally important in determining the 
general configuration of the crust. 

The Pass structure thus affords an admirable example of cross-folding and 
buckling due to the conflicting action of force-components, forming two unequal 
sets of force-couples, directed obliquely one against the other. 

6. Torsion-ellipsoid.—The axis of the anticline, which extends from 
Plon to Pescosta in a slightly west-south-westerly and east-north-easterly 
direction, is cut west of Plon by the Wolkenstein cross-fault, and east of 
Pescosta by the Pescosta (or Corvara) cross-fault. The two opposite centres of 
intrusive rock occur on the axial line, the western centre above the waterfall, the 
eastern centre above Ruon hamlet. With these two centres as foci and the 
antielinal axis as a main axis, an elliptical figure may be drawn, which will 
embrace the torsion-phenomena of the Gréden Pass. For convenience I 
propose to term this figure a torsion-ellipsoid. 

A straight line drawn at right angles to the major axis through the centre 
represents the minor axis of the ellipse, and, at the same time, the direction 
of the resultant forces acting inward on the anticlinal buckle, namely, 
in a direction slightly north-north-west and south-south-east. 

The maximum ‘interference’ in the fold-formation has taken place between 
the foci, where the northern and southern fold-ares have cut each other and 
interlocked. 

7. Characteristic furcation of diagonal faults.— Furcation 
takes place in what may be called a dichotomous fashion. ‘The main throw 
of a fault is taken up by the branch or branches in the new direction, while 
the throw either way be sensibly diminished in the continuation of the original 
direction, may die out. or may be replaced by a steep flexure or a series of con- 
tortions, according to the petrographical nature of the strata. 

Two diagonal faults in a north-north-easterly and south-south-westerly 
direction, and a third in a northerly and southerly direction, cut the focal area 
in the western slope of the Pass. A main diagonal fault crosses between the 
Gréden Pass and the Wolkenstein, and passes south-south-westward over the 
Sella Pass, sending off a branch due south. 

Upon the east side of the Pass, one diagonal fault crosses the focal area in 
a north-north-westerly and south-south-easterly direction, a branch passing 
due south into the Sella Massive. The Pescosta Fault is a main diagonal fault 


Fig. 8.—Diagram illustrating the torsion- 
movements at the Groden Pass. 


582 MISS M. M. OGILVIE [MRS. GORDON|oN THE [ Aug. 1899, 


separating the Gréden Pass area from the Pralongia and St. Cassian area. The 
fault runs in a north-north-westerly and south-south-easterly direction, but a 
branch crosses the Pass north and south towards Crap di Sella. These three 
faults afterwards furcate to south-south-west. Still two other faults occur 
farther east—one, the north-north-west and south-south-east fault at St. Cassian ; 
the other, the north-and-south fault which cuts off the Groden Pass Anticline 
finally against the Centurinus group. 

8. Correlation in form and structure between the anticline 
and the adjacent synclinal areas.—The diagonal faults of the Groden 
Pass and their furcations sweep closely round, or pass into, the Dolomite- 
massives occupying the synclinal areas north and south of the Gréden Pass 
anticline. The geological map (Pl. XL) shows that the diagonal torsion-faults 
in springing across and away from the anticlinal buckle permitted the virgating 
fault-blocks to be twisted away from the directions of strike into increasingly 
oblique directions. The various oblique positions assumed by such torsion- 
offshoots from the Pass anticline have determined the boundaries of the synclinal 
areas immediately adjacent to the Pass. 

Hence torsion-faulting is the basis of the correlation in form which obtains 
between the convex curves of the anticline and those of the adjacent Dolomite- 
massives. There is also a correlation in structure, since the opposite synclinal 
regions behind the main overthrusts and return overthrusts of the Pass anticline 
are clearly opposite regions of rock-distension, correlated with the Pass area 
of strong compression and even dovetailing of crust-folds. In the peripheral 
parts of the massives which immediately adjoin the anticline the rocks have 
undergone a thrust towards the anticline ; while in the internal parts, remote 
from the anticline, the rocks have subsided into deep troughs. 

A certain reciprocity of structure may be noted between individual synclinal 
basins on opposite sides of the anticline. It will be remembered that the 
synclines diagonally opposite each other have undergone the same direction of 
spiral twist. Thus the Spitz Kofl and Tschampatsch groups in the Gardenazza 
Massive are the reciprocals of the Pitz Kofl and Meisules groups in the Sella 
Massive. Again, a structural correlation has been indicated between the deep 
synclines of the Lang Kofi and Sass Songe mountains at diagonally opposite 
curves; and a correlation also exists between the shallow synclines of the 
Sta. Maria-Wolkenstein and the Pralongia meadows placed diagonally opposite 
each other at the north-western and south-eastern curves of the ellipsoid. 

9. Torsion-figures. — Oblique fault-angles are formed (a) when a 
diagonal fault directed north-north-east and south-south-west meets or intersects 
a diagonal fault directed north-north-west and south-south-east; (0) when a 
north-and-south fault meets or intersects any diagonal fault; (¢) in various 
cases of oblique intersection between longitudinal and cross-faults. The several 
possibilities 0. coincidence and intersection can be verified in the accompanying 
map (Pl. XL), tugether with the consequent formation of distorted lozenge- 
shaped and polygonal figures. 

Meantime, attention is simply called to such as occur in the Groden Pass. 
The two limiting-faults AB’ & A'B (fig. 7, p. 578) form an X shape, with elon- 
gated centre, disposed east and west across the Pass, while the areas between the 
arms of the X are laid out in long-sided V and W figures, with the intervention 
of small triangular wedges at sharp torsion-curves. ‘These forms are similar 
to the characteristic torsion-figures which were obtained experimentally by 
Daubrée. 

The chief joints and the cleavage-planes have the same oblique and inier- 
secting directions as the diagonal faults, and, like the latter, these finer planes 
of rupture veer round to directions parallel with the curving strike of the 
Pass folds. In short, the present author’s observations go to show that the 
torsion-figures, evident on a large scale in the general structure of the Pass, 
are equally demonstrable in the cleavage-phenomena of the rocks. 

10. Superposition of the torsion-phenomena upon pre- 
existing crust-folds.—tThe intimate association of the longitudinal bundles 
of faults and the furcating diagonal or transverse faults is unmistakable. 
Not only do fault-dykes pass uninterruptedly from one to the other, but also 
the stratigraphy on the opposite sides of a diagonal fault shows that the 


Wolter | TORSION-STRUCTURE OF THE DOLOMITES, 583 


occurrence of the fault permitted the strata on the one side to be twisted and 
faulted with different degrees of complexity, and sometimes in a different sense 
from the strata on the other. Therefore I regard these faults as a simul- 
taneously developed system of complex torsion-curves, due to the inertia of the 
rock-masses while undergoing torsion-deformation. xs 

At the same time, it is noteworthy that the fundamental form of an anticline 
everywhere underlies the torsion-phenomena. Disregarding for the moment the 
diagonal buckles, one anticline can be followed west and east from the Groden 
Valley to the Enneberg Valley. It has been cut by cross-faults at several points, 
and its axial line has been disjointed and displaced at such points, hence the 
anticlinal form would seem to be older than the cross-faults. ‘The Groden Pass 
area represents only one of the anticlinal segments, displaced laterally from its 
neighbours west and east by the Wolkenstein and Pescosta diagonal faults. 
Intrusive rocks are present in both of these faults, and are associated with the 
ramifying series of dykes which mark the system of torsion-faults in the anticline. 

These data lead me to infer that torsion-deformation took place subsequently 
to the determination of a meridional anticlinal buckle. The probability is 
that the torsion-phenomena represent a later and more com- 
plex phase of crust-movements, superinduced upon a simpler 
phase characterized chiefly by lateral compression. The evidence 
is that the simpler folds in the Groden-Enneberg area had their axes in almost 
meridional direction; whereas the more complex folds of the torsion-epoch 
have no straight axes. The torsion-folds are curved, and the torsion-faults lie 
in all possible oblique directions, displaying complicated phenomena of inter- 
section and reversal. 

The disposition of anticlinal buckles in curves circling round separate massives 
in the detached synclines is entirely a result of crust-torsion. 


Til. Tue Anticrine or tur BucHEeNstErn VALLEY. 


Northern slopes of the Buchenstein Valley.—Buchen- 
stein Valley is the name given to the upper part of the Cordevole 
Valley (see Pl. XL). The Cordevole stream flows east-north- 
eastward from the Pordoi Pass to Arabba, then bends east-south-east 
towards Pieve, and there curves sharply south-eastward. The curve 
described by the river is much the same as the curve described by the 
Groden Pass round the northern base of the Sella Massive, and it 
will be shown to be due to the same structural feature of torsion. 

The steep crags of Cherz Hill rise on the north of the valley. 
An old river-terrace occurs about 500 feet above the present river- 
level, where two groups of cottars’ houses are perched, called 
respectively Varda and Cherz. Dark precipices rise 1400 feet 
higher to the summit (about 7000 feet), and it is chiefly among these 
precipices behind Varda and Cherz that instructive rock-exposures 
are to be found. 

Southern slopes of the Buchenstein Valley.—The ridge 
of Belvedere and Sasso di Mezzodi shuts in the valley on the south. 
This is the ridge which has been already recognized on paleonto- 
logical grounds (see p. 562) as corresponding generally in position 
with the geographical limit of the different facies in Enneberg and 
Fassa during the Wengen-Cassian time. Enneberg then, in my 
opinion, represented the submarine terrace, which was at once 
the upthrow side of a contemporaneous Middle Triassic fault or 
flexure, and part of the area over which Middle Triassic lavas and 
tuffs spread inward from the active zone of crust-movement. We 


584 MISS M. M. OGILVIE [ MRS. GORDON | ON THE [Aug. 1899, 


have now to ascertain what changes were induced in this region 
of Middle Triassic disturbance during the Tertiary epoch of Alpine 
uprise. 

Cherz Hill overthrusts.—The accompanying diagrammatic 
sketch (fig. 9) shows an exposure observed among the rocks above 


Fig. 9.—Cliff-eaposure in the southern face of Cherz Hill, towards 
Varda, showing the origin of the so-called Buchenstein agglomerate. 


WK. MH. 7 aii 


S=Seis Limestone. Werf, FD = Fault-dyke. 

C=Campil Sandstone s ep Agg=Shear-and-contact breccia (so- 
and Shale. gem called Buchenstein agglomerate). 

B=Buchenstein banded limestone MK= Muschelkalk. 


and plant-bearing shales. 


[ All the rocks are altered at the zones of contact; the Werfen strata are 
crushed and streaked into the ‘ agglomerate’ at some points; the Muschel- 
kalk is broken up into huge wedges of ‘ agglomerate’ or dragged out into 
brittle paper-like lamine; the Buchenstein limestone and shales have 
been changed into black earthy or banded rocks; while green ‘ pietra verde’ 
and other highly altered rocks mark the zone of Buchenstein rocks actually 
next the wain fault-dyke. | 


Varda. Werfen strata and Muschelkalk occur here below the 
augite-porphyrite of Cherz Hill, at a height of 1000 feet above 
their exposure in the valley at Soraruaz, and are overthrust 
above the augite-porphyrite of the Arabba area. The overthrust- 
plane hades northward. 

Contact- and fault-alteration.—The overthrust series of 
rocks have been greatly compressed and sheared, the fossils found 
in the Werfen strata being squeezed and distorted. Patches of 
Werfen strata and greater masses of Muschelkalk have been rolled 
together with the intrusive rock into a shear-and-contact breccia. 
Here, as elsewhere, this mechanical complex has been regarded as 
a sedimentary series, the so-called ‘ Buchenstein conglomeratic 
limestone.’ Fig. 9 displays the true relation of the rocks to the shear- 
and-contact breccia particularly well, since it shows wedges of 
various horizons, more especially large blocks of Mendola Dolomite 


—_ 


~ 


Vol. 55. | TORSION-STRUCTURE OF THE DOLOMITES. 585 


still im situ in the midst of the brecciated shear-rock. Contact- 
alteration is everywhere evident along the many threads of intrusive 
igneous rock. 

Specimens of the intrusive rocks have been kindly determined for 
me by Prof. Watts. They include augite-porphyrite, aud a variety 
which might be described as olivine-melaphyre, together with a 
variety of liebenerite-porphyrite. 

The chief occurrence of the intrusive rock is as a fault-sill 
between a normal fault inclined north and with northerly downthrow 
and a reversed fault inclined north with southerly overthrust. It 
has been injected into a ruptured ‘ knee-bend’ flexure of the rocks, as 
at the Groden Pass. The figure also exhibits a transverse fault 
cutting the inclined faults and seamed with a thread of intrusive rock. 
The strata on either side of the transverse dyke have been strongly 
sheared and altered. Onthe west side is the familiar shear-and- 
contact breccia of Lower and Middle Trias; on the east side the 
Wengen Series is present, comprising true interbedded dust-tuffs and 
lavas, as well as fossiliferous shales and shaly limestones. There is a 
contact-zone not more than 12 inches wide,in which the Wengen 
rocks have been altered to easily-powdered greenish pseudo-tuffs 
answering to the general appearance of pietra verde. 

Oblique faulting across the Cherz overthrusts.-— 
The main overthrust is exposed chiefly in Muschelkalk horizons. 
A lower overthrust can also be distinguished in some places, slicing 
contorted fragments of the Werfen rocks along with the Muschelkalk. 
Both are cut off on the middle slopes helow Sella by the diagonal 
north-north-westerly and south-south-easterly, or Campolungo 
branch from the Pescosta Fault (p. 573). 

The most remarkable feature about the Cherz Hill overthrusts is 
that the rocks have not been sliced along continuous planes, but 
as a number of oblique torsion-wedges, each wedge showing a certain 
individuality in the precise stratigraphical relations of the inclined 
faults (see fig. 10, p.586). A radiating bundle of these oblique faults 
occurs behind Varda, and has given the overthrust group of rocks 
the twist which has carried them round to the west-north-west. 

The small area of Varda offers an example of a fold overcast 
primarily towards the south, but sliced obliquely across its strike 
into a number of movable pieces, capable of being twisted and set in 
a new direction of strike, at the same time that the strains of com- 
pression induced overthrusting. 

The Prilongia-Soraruaz diagonal fault.—An im- 
portant vertical diagonal fault cuts the Pralongia meadows in 
a north-and-south direction, crosses the Buchenstein Valley, and 
curves south-south-westward near Soraruaz. This fault runs parallel 
with the Campolungo Fault, and both throw down the strata on 
the west: that is, towards Sella. The Soraruaz Fault marks also the 
median line dividing the eastern and western portions in the torsion- 
system of the Buchenstein anticline. 

Whereas the Arabba, or western part of the anticline, 1s charac- 
terized by the exposure of an intruded sheet of porphyrite in the 


Fig. 10.—Parallel sections from Monte Sief and Cherz Hill to the 
Buchensten Valley, on the scale of ae 


N. 
Sett Sass, Richthofen Monte Sief, Coi di Lana, 
2562 metres. Riff. 2426 metres. 2464 metres. 


Cross-fault. 
Contrin & Castello Ruaz Fault, passing into 
Fault. the Pieve Overthrust. 


SD=Schlern Dolomite. Mk=Muschelkalk. 
C=Campil Sandstone and Shale. | LM=Lower Muschelkalk. 
Weg=Wengen strata. Wf= Werfen strata. 
B=Buchenstein limestone and shales. | TPl1=Thrust-planes. 
Agg=Shear-and-contact breccia. 


[The western portion, between the Campolungo-Cordevole and the Pralongia- 
Soraruaz cross-faults, is twisted from the eastern portion, comprising Monte 
Sief and Pieve. ] 


Fig. 11.—Faults in the fold-form of the Buchenstein Valley. 
N. 8 


iy Lye L Dl Ld S| 


Fig. 12.—Fold-form of the Buchenstein Valley and Sett Sass (for 
comparison with fig. 3, p. 568). 
N. 5. 


Fr Or 
Nolen] THE TORSION-STRUCTURE OF THE DOLOMITES. 58% 


main body of the fault-network, the Pieve, or eastern part, 1s 
characterized by wonderful exposures of highly-folded and strongly- 
sheared Werfen rocks and Muschelkalk (including the uppermost 
horizons representing true Buchenstein strata), arranged as a fan of 
fault-blocks virgating eastward. 

The overthrusts in the Pieve area.—The uppermost of the 
Cherz Hill overthrusts is twisted eastward by the Soraruaz Fault 
into Col di Lana; the lower descends the Gliera slopes in a west- 
north-westerly and east-north-easterly direction, but it is twisted 
into a westerly and easterly direction near St. Johann by intersection 
with a subordinate oblique fault, and continues through the Federa 
fields into Col di Lana. The divergence of these overthrusts towards 
Col di Lana is in remarkable contrast with their overlapping position 
in the Varda area. 

Another strike-fault runs south of these from Soraruaz, in a west- 
north-westerly and east-south-easterly direction, to the slopes of Col 
di Lana, immediately above Pieve. The throw of this fault is 
different on the east and west of its intersection with the St. Johann 
oblique fault. 

It has thus been demonstrated that the crushed buckle of older 
Trias at Soraruaz and St. Johann is flanked on the northern wing 
by S-folds, with southerly overthrusts. Although the accompanying 
map (Pl. XL)* does not include a survey of the Belvedere ridge, 
the general northerly dip of the Muschelkalk rock in the middle and 
higher exposures of that range, as contrasted with the inward dip of 
the Muschelkalk in the lower hill-horizons, would seem to indicate 
the presence of a back-fold in the southern wing of the anticline. 

The curved normal fault between the northern 
wing of the anticline and its correlated syncline.— 
Once more we find a steep flexure broken by a normal fault as the 
means by which a series of reversed faults has been neutralized. 
The flexure is best seen on the northern slopes of Monte Sief 
(fig. 10, p.586). The Wengen strata strike north 40° east and dip 35° 
westward on the mountain, while the Wengen-Cassian Series of Pra- 
longia, with a nearly east-and-west strike, and northerly dip, comes 
into contact with the bent series of Monte Sief along a flexure-fault 
with downthrow to the north. The fault describes a torsion-curve 
from west-north-west at Campolungo, round a southern arc 
through Monte Sief to east-north-east, where it is cut by the Val- 
parola diagonal fault. This curved normal fault bounds the 
syncline of Pralongia and Sett Sass. 

The Buchenstein torsion-system.—tThe Pordoi-Pass area 
of this region represents a portion of the northern wing, very deeply 
sunk in comparison with the Varda portion of the same wing. It 
will be dealt with more conveniently on a subsequent page (p. 599). 
Sufficient data have been already given to afford a clue to the com- 
plete system of torsion in the Buchenstein region (see fig. 13, p. 588). 


* The stratigraphical details of the Buchenstein virgating faults can be seen 
in the map; the paths marked on the map are old footpaths, now in great 
measure obliterated, owing to the building of fortifications and the laying-out 
of strategical roads at present going on in the valley. 


RADE BOY OULAD, SSE: 


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Vol..55-] THE TORSION-STRUCTURE OF THE DOLOMITES. 589 


First, one observes that the divergent faults east of the Soraruaz 
diagonal fault curve variously north-eastward and south-eastward, 
whereas the faults west of the Soraruaz Fault curve north-westward 
round Cherz, and south-westward through the Arabba Hills. 
Further, that the chief oblique faults intersecting the eastern fault- 
bundle are north-north-west and south-south-east in direction, 
whereas those across the western bundle are north-north-east 
and south-south-west in direction, becoming north-east and south- 
west and east-north-east and west-south-west in the strongly- 
compressed part of the Cherz Hill curve. 

From a knowledge of the Groden Pass and a comparison of figures, 
it is not difficult to recognize two opposite fold-ares, meeting in a 
central area (Soraruaz) of fold-intersection and maximum torsion- 
shear. The torsion force-couples have induced clockwise torsion 
in the north-western and south-eastern quarters, counter-clockwise 
torsion in the north-eastern and south-western quarters. 

If a straight line be now drawn from Canazei in the Avisio Valley, 
through the area of intersection and north of Monte Sief, to meet 
the Valparola stream, the line will have a west-south-westerly and 
east-north-easterly direction’ parallel with the line followed by the 
main torsion-fault of the Groden Pass. Such a line, moreover, will 
be found to correspond with an actual line of contact in nature, 
between an intrusive igneous sheet and the Wengen strata exposed 
on the Pordoi, Sella, and Cherz slopes. The natural line varies 
from the drawn one only where the former follows the contours of 
Campolungo and Cherz above the Arabba stream. The line from 
Canazei to the Valparola stream is recognizable as the chief torsion- 
strike, while a subordinate torsion-strike runs from west-north-west 
(Cherz Hill curve) to east-south-east (Pieve and Cordevole Valley 
curve). 

The complete torsion-system of Buchenstein may be embraced 
within an elliptical outline, and, just as in the case of the Grdden 
Pass, there are opposite areas of subsidence behind the northern 
and southern wings of the anticline respectively. Sella and Sett 
Sass represent two segmented portions of the northern synclinal 
area separated by the diagonal buckle of Campolungo, while the 
Marmolata mountain represents the southern synclinal area. 

Relation of Col di Lana to the Belvedere ridge.— 
The petrographical similarity between the rocks of Col di Lana and 
Cherz Hill on the one hand, and those of the Belvedere ridge on the 
other, has been the subject of frequent comment by geclogists. The 
apparent thickness of the rock-complex on Col di Lana and Cherz 
Hill is due to the occurrence of the overthrust-planes. Now, the 
system of torsion-faults set forth above explains Col di Lana and 
Cherz Hill as obliquely-twisted segments forming the northern fold- 
are of the Buchenstein Anticline, whose southern fold-are is formed 
by the Belvedere ridge. Thus, instead of Col di Lana representing 
an individual centre of eruption in Middle Triassic time, as suggested 
by some, it is shown by its stratigraphy to have been originally a 
homogeneous part of the Belvedere body of strata. 


590 MISS M. M. OGILVIE [MRS, GORDON] ON THE [Aug. 1899, 


East-and-west cross-faults limiting the Buchenstein 
torsion-system.—The western extremity of the Belvedere 
ridge, named Cima di Rossi, is separated from the Rodella Hill 
complex of similar rocks by the fault over the Sella Pass (p. 570) 
towards Canazei. This transverse fault is accompanied here by a 
fault-dyke continuous with the intrusive sheet in the strike-shears. 
The Rodella fault-block west of the transverse fault has heen twisted 
in counter-clockwise direction to the east-north-east, and the Cima di 
Rossi block, east: of the transverse fault, has been twisted also in 
counter-clockwise direction, but to the west-south-west. Referring 
to the diagram of torsion (fig. 8, p. 581), the Rodella block and the 
Cima di Rossi block represent the B & D force-spirals respectively 
in two adjacent torsion-systems. 

Again, the downthrow of the transverse fault is on the east side, 
towards Sella; the fault therefore neutralizes the sum of the diagonal 
faults through Sorarnaz, Campolungo, and Bova Alp (p. 599), whose 
downthrow is in ali three cases on the west side, towards Sella. 

The limiting cross-fault east of the Buchenstein torsion-system 
is the Valparola Fault, with an easterly downthrow. 

If we now in imagination turn back the intercrossing axes of the 
torsion-strikes into straight line one with another, Cima di Rossi 
would be brought into touch with Rodella at the western extremity 
and Col di Lana with Monte Padom at the eastern. 

Superposition of Tertiary upon Triassic strike.— 
I previously pointed out the obliquity of Tertiary lines of crust- 
movement to pre-existing lines of Triassic disturbance (see p. 563). 
The probable relation of the later movements to the earlier may 
now be indicated, in accordance with the results obtained. 

A Middle Triassic flexure or fault, with an east-and-west strike in 
this particular locality, was acted upon obliquely during the Tertiary 
upheaval by combined movements of compression and torsion, after 
the manner described in the case of the Grodden Pass. While the 
new movements apparently concentrated themselves along the pre- 
existing lines of crust-weakness, the new crust-buckles took shape 
across the former strike in the form of cross-folds, and the move- 
ments culminated in oblique shears and diagonal and transverse 
ruptures, accompanied by the injection of dykes and sheets in the 
curved faults. The overlapping or virgating shear-wedges of torsion 
then gradually adjusted themselves in the new directions of strike, 
while adjacent fault-blocks settled themselves on opposite sides of 
the diagonal and transverse ruptures, such movements of adjustment 
taking place along fault-planes primarily determined during the 
period of active torsion. 


IV. Tae Serta Massive. 


The Sella Massive presents a highly characteristic type of the 
mountains in the Southern Tyrol Dolomites. 

The geological map published by Mojsisovics! gives expression 
to the theory that Sella Mountain was pre-eminently a coral-reef 


1 «Die Dolomit-Riffe von Sid-Tirol u. Venetien,’ 1879, chap. viii, pp. 227-240. 


Wok ss. TORSION-STRUCTURE OF THE DOLOMITES. 591 


formation built during the Wengen, Cassian, and Raibl periods, 
having been formed in continuity with the ‘Lang Kofl Reef’ during 
Wengen and part of Cassian time. The following paragraphs 
give an account of the researches made and conclusions arrived at 
by the present author in the years 1892-1896. 

Structural significance of the ravines of Val la 
Stries and Val di Mezzodi.—The Sella Massive occupies an 
area of subsidence, elliptical in outline. The Groden Pass Anticline 
curves round it on the north, the Cima di Rossi portion of the 
Buchenstein Anticline curves round it on the south; the Campo- 
-lungo diagonal buckle limits it on the east, and on the west the 
diagonal buckle of the Sella Pass dips towards it. 

Two long narrow valleys with precipitous sides run up into the 
heart of the Sella Massive. The one is Pissadoi ravine, called also 
Val di Mezzodi, ascending from the Gréden Pass south-south- 
westward to the hanging glacier which descends from the Boe ridge ; 
the other is Val la Stries, ascending from the Sella Pass eastward 
to the Boe ridge. Their axial lines would meet in the middle of 
the mountain at a wide angle, and the direction of curve which 
would thus be suggested is parallel with several important diagonal 
fault-curves through the east side of Sella. Itis, moreover, practically 
the axis of the torsion-ellipsoid of Sella itself. 

The line of section shown in fig. 14 (p. 592) runs north-west 
and south-east, as nearly as possible transverse to the direction of 
this curve. A second line of section is also given north and south, 
cutting transversely a subordinate direction of strike in the mountain 
(fig. 16, p. 594). The strike of the rocks curves round from one 
direction to another, holding parallel with the peripheral outline of 
the massive. The dip is, in the main body of the mountain, 
inward to the centre, but near the periphery the rocks, especially 
on the south and east sides, dip outward. 

Pitzculatsch exposures.—tThe first part of the line of 
section (fig. 14, p. 592) passes from Plon over Pitzculatsch to that 
corner of Sella which is known as the Griiner Fleck, and thence 
over the high precipices of the Meisules terrace. 

The Pitzculatsch Fault has been already described (p. 567). 
South of it, in its immediate neighbourhood, true ‘ Buchenstein 
limestone’ (see footnote, p. 569) is wedged into the grass of the steep 
slopes in block-form, and probably represents sheared rock. The 
dark, banded limestone and tufaceous strata at the base of the 
Wengen Series have a considerable surface-outcrop, and can be 
examined in stream-courses. The general strikeis north 60° to 65° 
east ; the dip is about 50°, but diminishes to 30° nearer Sella. 

A Cipit-Limestone horizon follows, which marks locally the limit 
between Wengen and Cassian strata, and has been previously termed 
‘ Lower Cassian’ by the present author on account of its containing 
the first indications of the Cassian fauna. Its character on the 
Pitzculatsch slope of Sella is precisely the same as that which is 
to be seen in the typical area of Priilongia." 


1 Quart. Journ. Geol. Soe. vol. xlix (1893) p. 16. 


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Vol. 55. ] THE TORSION-STRUCTURE OF THE DOLOMITES. 093 


Large weathered blocks full of coral- and encrinite-remains are 
characteristic of the horizon, and were first described by Richthofen 
in the Cipit stream between Schlern and the Neisser Alp. 

At Pitzculatsch there follows above this horizon a certain thickness 
of interbedded limestones and marls dipping about 30° towards the 
mountain. I found in these a typical ‘Stuores’ Cassian fauna, 
and followed the outcrop towards the Groéden Pass. Not only are 
the fossiliferous marls present, but also the higher horizons of more 
thickly-bedded brownish-yellow limestone, full of Cidaris-spines and 
other small fossils. The same zone of Cassian limestone is present 
on the ridge of Prilongia above the Stuores meadows. 

Here, at Pitzculatsch, the yellow limestones are followed by thickly- 
bedded calcareous horizons with numerous encrinite-remains and 
blocks of coral-growth, and then succeeds the ‘ dolomite -cliff of 
Gruner Fleck. But, so far as I could examine it, this last rock gave 
a distinctly acid reaction. 

This section therefore proves a conformable succession of the rock 
called Schlern Dolomite (although largely calcareous in certain 
places) upon marls and limestone containing a typical ‘Stuores’ or 
Middle Cassian fauna. No individual zone is wanting which has 
been demonstrated and fixed paleontologically by the writer in the 
survey of the neighbouring typical area of Pralongia and Stuores. 
Hence there is no reason whatever for mapping the dolomitic 
limestone here as a ‘reef-built facies’ corresponding in age to a 
‘bedded facies’ of earthy deposits. It succeeds the Wengen-Cassian 
Series conformably, and is therefore geologically younger than these 
strata. 

Peripheral overthrust of Sella at the Griner 
Fleck.—The precipitous cliffs of the Meisules group in Sella sur- 
mount the Pitzculatsch hill. Griiner Fleck is the name given to 
a grassy ledge midway up the rocks at the north-western corner. 
Even from below it can be observed that the ‘ Schlern-Dolomite’ 
rocks below the Griner Fleck dip steeply inward with the general 
dip of the Pitzculatsch succession, whereas the ‘ Schlern-Dolomite ’ 
rocks of Meisules are almost horizontal, and in their continuation 
towards the Groden Pass dip outward from the mountain. 

This difference becomes still more evident when an ascent is 
made to the Griiner Fleck. Cassian marls and calcareous rocks are 
present on the ledge, and share the strike-and-dip relations of the 
Meisules terrace. Both the Cassian marls of the Grier Fleck and 
the overlying dolomite meet the lower dolomite along a disturbed 
shear-plane; an overthrust of certain horizons of the Cassian strata 
and the overlying Schlern Dolomite has taken place above the same 
horizons of rock in the Pitzculatsch conformable succession, upon a 
plane inclined south-eastward gt an angle of about 50°. Con- 
firmatory evidence of the thrust-plane is afforded in the cliffs facing 
the Groden Pass. 

Immediately east of the Gruner Fleck no Cassian strata are 
apparent in the overthrust-group. Farther round, however, Cassian 
strata come increasingly into evidence, while below the shear-plane 


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Volgs.| THE TORSION-SIRUCTURE OF THE DOLOMITES. 599 


the Schlern Dolomite (which is not less than 500 feet thick below the 
Griiner Fleck) has been gradually cut away by the thrust-plane, 
so that it thins out to mere streaks of sheared and smashed rock. 

Opposite the highest point of the Groden Pass the Cassian strata 
above and below the shear-plane almost meet; but the difference in 
their dip-and-strike relations is perfectly distinct, since the Cassian 
strata above the shear-plane incline outward, and those below 
dip from 25° to 40° inward. The shear-plane descends from about 
the 2300-metre contour-line at the Griiner Fleck to 2200 opposite 
the Pass height, and to 2150 at its exposure in the Pissadoi Ravine. 

In the direction of the ravine.the dolomite again thickens below 
the shear-plane, a circumstance which is associated with the general 
west-south-westerly and east-north-easterly strike of the conformable 
-succession of Wengen, Cassian, and Schlern-Dolomite strata on the 
Pass. The course of the shear-plane through the cliffs is marked by 
patches of vegetation, wherever the Cassian strata have been 
weathered out along the exposure of the plane. 

While the Schlern Dolomite below the shear-plane is a variabie 
factor with regard to thickness, that above the shear-plane is 
practically constant in this respect, and represents the complete 
thickness, where it has Cassian strata at its base and Raibl strata 
.on the top of the Meisules terrace. This thickness may be estimated 
as 1100 feet at the most. 

Immediately west of the Griiner Fleck the relations of the shear- 
plane are disturbed by a scree-slip, which seems, from the strati- 
graphical features on either side, to coincide with a small transverse 
fault. Beyond it, the precipitous walls of dolomite correspond to 
the similar precipices next the Griiner Fleck on the Groden-Pass side. 
The position of the shear-plane, however, can be still determined 
by differential strike and dip, and is also indicated by a well-marked 
horizontal fissure through the rock. 

The dolomite below the shear-plane forms an outjutting crag, 
named Buscatins on the local map. Together with the Cassian 
strata below it, the Schlern Dolomite of Buscatins strikes towards 
the Ciavatzes Alp, and is gradually cut out in that direction. On 
the top of Buscatins indications of Cassian limestone are present, 
but scree (and what is probably shear-breccia) cover the terrace 
between Buscatins and the western face of the Meisules cliffs. 
The line of scree continues southward into the midst of the Cassian 
strata exposed on the Sella Pass. These occupy the Pass-ridge 

from about the 2275-metre contour up to 2400 metres. The dip 
changes in this group of Cassian strata. The strata below the 
Sella Spitze have the almost horizontal position of the younger rocks 
forming these summits, whereas the Cassian strata on the Sella- 
Pass ridge have a steep and variable north-north-easterly dip. The 
Wengen strata, so widely exposed over the Sella Pass, are here 
“highly contorted. 

In the ravine of Val la Stries the Cassian strata are slightly 
-inclined, as at the Sella Spitze. They correspond to the Meisules over- 
thrust series, and are succeeded by Schlern Dolomite in its normal 

292 


596 MISS M. M. OGILVIE [MRs. GORDON] oN THE [Aug. 1899, 


thickness of about 1100 feet. The overthrust-plane may be said to 
disappear from view when it enters the Cassian strata of the Sella 
Pass. Considerable tectonic disturbances are, however, evinced in 
the Wengen-Cassian group wherever exposures are found on the 
southern slopes of the Sella Pass towards the Salei stream, and on 
the steep descent of Val la Stries towards Roja. The soft strata 
are twisted in all directions, and riddled with small faults. This. 
is the explanation of the wide surface-outcrop attained by Wengen 
and Cassian strata, more especially the former, on the south-west 
side of the Sella Massive. 

The contorted Wengen-Cassian strata and the sheared fragments. 
of Schlern Dolomite below the thrust-plane form part of the anti- 
clinal group of strata belonging to the south-western quarter of the 
Groden-Pass torsion-scheme, while the strata above the thrust-plane 
represent a back-fold from the correlated part of the Sella syncline. 
Differential movements of torsion have taken place here in super- 
posed horizons of the earth’s crust, the upper horizons having been 
twisted northward and north-westward, while the lower horizons 
were twisted southward and south-eastward. The shear-plane has 
passed spirally through the Wengen-Cassian Series of softer strata 
and also the more resisting Schlern Dolomite. 

The torsion of the thrust-fold into an are-shape is cognate with 
the torsion of the strike of the rocks. Thus the Meisules fold-are 
forms a southern curve in the virgating group of torsion-curves 
demonstrated on the west of the Groden Pass. The heaping-up of 
the calcareo-dolomitic strata towards the north and north-north-west 
is correlated with a general attenuation of these strata in the internal 
portion of the massive, and a consequent sinking of Jurassic strata 
along a curve parallel with the curve of the Meisules fold-arc. 

The Pordoi Pass overthrust.—The Pordoi Pass forms 
what is usually regarded as the southern limit of the ‘Sella Mountain. 
It extends east and west between two wide outcrops of the Wengen- 
Cassian Series, here, as at the Groden Pass and the Sella Pass, 
strongly contorted and often faulted. 

The Pordoi Spitze are southern summits of the Sella Massive 
which stand north of the Pass and exhibit an undisturbed succession 
of Schlern Dolomite, Raibl, and Dachstein-Limestone strata dipping 
slightly outward. On-the south side of the Pordoi Pass the summit. 
of Sasso Pitschi (Sasso Beccie) rises from the midst of the Wengen- 
Cassian Series. It is composed of Schlern-Dolomite rocks, not only 
dipping steeply north-westward, but also showing actual twists in 
the strata similar in direction to twist-curves which can be seen in 
the Dachstein Limestone that forms the highest summit (Boe) in the 
massive. The disturbed stratigraphy of Sasso Pitschi offers a 
marked contrast to the gentle outward dip of the strata on the 
opposite Pordoi summits. 

The differential dips are separated by the Pordoi Pass overthrust- 
plane, which hades northward: I have described the details on 
a previous occasion.’ Sasso Pitschi presents a lower slice of 


1 Geol. Maz, 1894, pp. 53-54 & fig. 


Vol. 55.] TORSION-STRUCTURE OF THE DOLOMITES. O97 


Schlern-Dolomite rock below the shear-plane, while the Cassian 
strata on the Pordoi Pass are above the shear-plane. Thus the same 
relations hold between Sasso Pitschi and the Pordoi summits as 
between the rocks of the Griiner Fleck and the Meisules group in 
the north-west of Sella. One important fact is that in every part 
of the circuit so far Wengen and Cassian strata have 
preserved precisely the same palwontological and 
petrographical features. 

The direction of the torsion-movements associated with the Pordoi 
overthrust is indicated by the change of strike and dip in the over- 
- thrust group on the east and west sidesof the Pordoi summits. On 
the west side, towards Val la Stries, the Schlern Dolomite strikes 
almost due north-and-south, and dips from 5° to 10° inward. A small 
transverse fault east of the Pordoi summits marks a sharp curvature 
of the strike to west-north-west and east-south-east, and it then 
turns gradually eastward, while the dip is as much as 15° to 20° 
outward. The Sasso Pitschi fault-block has likewise a rapidly 
twisted strike, from west-south-west and east-north-east opposite 
Monte Forca to south-west and north-east a little lower down the 
Cordevole slopes. The dolomite-rocks of Sasso Pitschi show abun- 
dant evidence of shear-brecciation and slickensides. 

The strike-torsion therefore describes an arc from west to east 
round the southern curve of the Sella Massive, comparable to the 
torsion-curve round the south of Cherz Hill opposite Arabba 
(p. 585). The shear-plane is also similarly inclined in the two 
places. These features indicate that the Pordoi portion of Sella 
represents a fold-arc in high horizons of the northern wing of the 
Buchenstein torsion-system. At the same time it is asunken block 
occupying an area of tension between the two opposite and divergent 
torsion-curves of the main anticline, namely, the northern or Varda- 
Cherz curve and the southern or Belvedere—Cima di Rossi curve. 
The fold-are has been broken, and the overlay and underlay of the 
fold have been twisted differently. The shear-zone occurs chiefly 
in the Wengen-Cassian Series, while the Schlern-Dolomite rocks 
that form Sasso Pitschi represent a torsion-wedge caught in an area 
of cross-movement and sharp curvature. 

Recognition of rocks on the east side.—The eastern 
side of Sella, facing Campolungo Pass and Cherz Hill, proved an 
arduous field to examine. It is much cut up by faults, and the 
greatest care has to be exercised in identifying the rocks belonging 
to each fault-segment. The chief difficulty is in respect to the age 
of the dolomitic rock, as the Dachstein-Limestone horizon is in great 
measure dolomitic, and can be distinguished from Schlern Dolo- 
mite only by a persevering search for fossils. Fortunately Megalodon 
triqueter, the typical Dachstein fossil, occurs very namerously 
throughout the Dachstein rock-horizons in most parts of Sella, and 
the higher Dachstein horizons are full of smaller bivalves ,and 
gasteropods. 

The Raibl strata are easily recognized from their petrographical 


598 MISS M. M. OGILVIE [MRS. GORDON] ON THE  [ Aug. 1899, 


character wherever they have been exposed to weather-action. 


Brownish fossiliferous sandstones at the base ; rose-tinted or chalky- 


looking dolomitic flagstones, sometimes with beds of dolomite; 
brilliant red, violet, and greenish marls, and an interbedded fine, 
variegated, or pale breccia always form the series of Raibl strata as. 
observed by me at Sella, Sett Sass, Sass Songe, and other localities. 
The few fossils found in this series on the Sella Mountain were 
typical Raibl species, and they were found in the brownish sand- 
stones. Ostrea montis-caprilis and Gervillia Bouéi were the most 
characteristic types in these. 

The Schlern-Dolomite rock proved often highly calcareous, 
and it was found to be comparatively easy to identify it on the 
east side, in spite of the disturbed stratigraphical relations, after 
the minute examination previously made on the west side up Val 
la Stries. It contains Cidaris-spines and highly-altered crystalline 
outlines of molluscan shells in great numbers; encrinite-remains 
and algal structures at all horizons; occasional banks of coral- 
growth ; and sometimes good specimens of sponges. In the highest 
horizons the rock showed drusy cavities, with large gasteropoda in 
them resembling the Chemnitzia found in the Wetterstein lime- 
stone, although unfortunately I did not succeed in getting them 
out of the cliffs. Only fragments of these and of the bivalve-shells 
could be secured. 

The Schlern Dolomite of the Sella Mountain is emphatically more 
calcareous and more fossiliferous than the Raibl Series. The 
latter is clearly a deposit which was originally magnesian. The 
fossiliferous sandstones at the base may be said to mark the gradual 


transition from the generally deeper-sea conditions of the previous 


period to the shallowing and variable conditions of Raibl time.’ 
Pian de Sass.—The name of ‘ Pian de Sass,’ sometimes written 
-* Plan de Sass,’ is given by the country-people to a shelving terrace 


on the east side of Sella. As often happens, the application of the 


name in the Government Survey map differs from the common usage 
in the district. That map (scale sis) places the name opposite a 


rounded summit at the southern end of the terrace overlooking 
the Campolungo Pass. But the smaller Survey map, on the scale of 


ie aa places the name on another outstanding rock close to a ridge 


at the northern end of the terrace, where there is a col between 
Corvara and the Campolungo Pass. 

I understand that this northern rock was the one visited by 
Prof. Rothpletz, and described by him* under the name of Pian de 


t «Coral in the Dolomites,’ Geol. Mag. 1894, p. 49 & pl. ii. ee 

2 “Geol. Querschn. durch die Ost- - Alpen,’ 1804, p. 55. I may be allowed 
to remark that my own early observations on Pian de Sass were made in 
1892-93 without any knowledge of those made by Prof. Rothpletz. In jthe 
course of subsequent conversation with him, I was pleased to find that our 
observations agreed in two important respects—(1) the identity of the Pian 
de Sass rock as Schlern Dolomite, and not Dachstein Dolomite, as mapped by 
Mojsisovies ; (2) the existence of a transverse fault on the east side of Sella with 
dowuthrow to the west. 


a 


Vol. 55.] TORSION-STRUCTURE OF THE DOLOMITES. 599 


Sass. As a matter of fact, the rock at the northern end of the 
terrace is called Cra di Mont in the district, and that of the southern 
end is called Col di Stein, while the terrace is variously spoken 
of as Pian de Sass or as ‘the Lago,’ from the presence of a small 
tarn on it called Lago di Boe. 

The torsion of the Pordoi overthrust at Bova Alp.— 
To return now to the circuit of Sella, the only means of tracing the 
Pordoi overthrust-fault eastward is by following the continuation 
of the different strike-and-dip systems of the Pordoi and the Sasso 
Pitschi fault-blocks, respectively above and below the shear-plane of 
the Pordoi Pass. In this way the fault may be traced in an east- 
north-easterly direction as far as the Bova-Alp corner of Sella, 
where the dolomite-rocks curve sharply northward. The curvature 
is very unexpected, since the strike of the Pordoi series is almost 
eastward and the dip slightly outward. 

The sharp curvature takes place where the Pordoi overfold is 
intersected by a diagonal torsion-fault directed north-north-east and 
south-south-west, parallel with a diagonal buckle that runs through 
the eastern side of the mountain. The overfold is broken up into 
several shear-slices on that side.1 The diagonal fault crosses the 
Cordevole Valley towards Col di Luc, but is subdivided into several 
branches where it enters Sella. The north-north-east and south- 
south-west branch passes through the mountain to the Groden Pass ; 
its downthrow is westerly. A north-north-west and south-south- 
east branch crosses the Pissadoi Rayine towards Ruon (p. 571); 
its downthrow also is westerly. 

Strata below the shear-plane (east side).—The Wengen 
Cassian Series on the upthrow or east side of the Bova-Alp diagonal 
fault is thus raised high on the Bova Alp relatively to the Schlern 
Dolomite of the mountain. The Wengen strata are the typical 
tufaceous shales and succeeding calcareous horizons; the Cassian 
strata include the fossiliferous marls with interbedded banks of Cipit 
Limestone, and the high horizons of thick-bedded yellow limestones 
crammed with echinoderm-remains. The average reading of the 
strike in these strata between the Bova Alp and the Campolungo Pass 
is north 30°, 35° east, dip 40° west, which would indicate that the 
Wengen-Cassian Series here is the continuation of the group of 


1 This is a case in point where a diagonal fault (which may be said to be 
transverse, as it cuts an overfold across its strike) cannot therefore be said to 
have originated subsequently. The phenomena of shearing differ on the oppo- 
site sides, hence the probability is that here is an example of contemporaneous 
faulting and shearing. I have treated this and similar cases in the Buchen- 
stein Valley and the Groden Pass as evidence of crust-torsion. The diagonal 
fault and the overthrust have both crossed obliquely an older east-and-west fold. 
I wish to emphasize this strongly, as in Alpine literature the great transverse 
(diagonal) faults of the Alps are considered to be in the main a set of phenomena 
subsequent to the thrusting in the Alps. But the transverse faults cannot be 
said to be of later origin, unless it can be proved that the thrust-phenomena 
on both sides of the fault are identical. In the Sella area virgating bundles 
of faults occur towards any geographical direction; some members of a bundle 
may be shear-faults, while others may be vertical, but there is every reason 
to consider them the result of one set of torsion crust-movements. 


600 MISS M. M. OGILVIE [MRS. GoRDON| oN THE [Aug. 1899, 


strata buckled below the peripheral shear-plane on the south of 
Sella. 

Some thickness of Schlern Dolomite surmounts the Cassian strata 
on the Campolungo Pass, and has the same strike and dip as these 
strata. The dolomitic rock has been weathered into fantastic needles 
and large irregular blocks, cleavage-slabs of the rock forming the 
dominant structural feature, although in places the planes of strati- 
fication may be clearly distinguished. Cleavage has taken place 
parallel with the strike, and also in a north-and-south direction 
(see fig. 21, p.614). These intersecting sets of cleavage-planes give 
evidence of an actual twist of the overfold at the Campolungo Pass. 

The Campolungo-Pass outcrop of Schlern Dolomite thins out south- 
ward towards the Bova Alp, and is cut off onthe north. At the same 
time, certain lenticular patches of Raibl strata are present at intervals 
on the top of the Schlern-Dolomite streak. The most vividly 
coloured and largest of these occurs on the mountain-slope imme- 
diately west of the needles of Schlern Dolomite, and at a higher 
level than the latter. 

Strata above the shear-plane (east side).—A moun- 
tain-shelf composed of Schern Dolomite and Raib! strata rises above 
the Bova Alp, and the same horizons of rock continue throughout 
the east side of Sella in the form of a diagonal north-north-easterly 
and south-south-westerly anticlinal fold, with strata dipping eastward 
and westward. Schlern Dolomite, with a strike north and south, dip- 
ping 30° westward, and a slight easterly flexure, forms the prominent 
rounded summit of Col di Stein and the shelving terrace of Pian de 
Sass, north of Col di Stein. The upper surface both of the summit 
and terrace is wavy, and the strata show frequent contortions. 
Raibl rocks are present at the top of the terrace in complete succes- 
sion, conformably overiying Schlern Dolomite. Large blocks of Dach- 
stein Limestone are strewn over the terrace, some of them containing 
numerous specimens of Megulodon triqueter ; there is, however, no 
Dachstein-rock an situ on the terrace. 

The strike of the rocks curves round on the terrace from north 
and south to north-north-west and south-south-east in the upper 
part, where the dip is inward, and to north-north-east and south- 
south-west in the lower levels of the terrace, where the strata dip 
outward. The strata are, in short, twisted in different directions. 
The cleavage-planes cross each other in northerly and southerly and 
north-westerly and south-easterly directions. 

The outward-dipping lavers of Schlern Dolomite descend to the 
grassy slopes between the Campolungo Pass and the Corvara Pass, 
and meet there Cassian marls and limestones with a north-easterly 
strike and a steep dip towards the terrace. 

Associated fold-fracture and strike-torsion. — I 
have frequently heard the opinion expressed that the Raibl patch 
west of the Campolungo Pass is merely a slipped fragment from 
the complete succession of Raibl strata on the Pian de Sass terrace 
above. But that by no means explains all the facts as they may be 
observed in the neighbourhood of the Bova Alp and Pian de Sass. 


Vol. 55.] _ TORSION-STRUCTURE OF THE DOLOMITES. 601 


I regard the Campolungo-Pass exposure of Schlern Dolomite, 
together with the irregular appearances of Raibl rock above it, 
as fragments of underfolded strata which have been steeply tilted 
down to the north-west, and twisted obliquely beneath heavy 
overfolded masses with easterly flexure. The overlay of the fold 
comprises the strata on the Pian de Sass terrace and the summit of 
€ol di Stein. The underlay of the fold comprises the strongly- 
sheared strata between the Campolungo Pass and the Bova Alp 
corner (fig. 14, p. 592). 

According to this view, the needles of Schlern Dolomite which 
stand upon the Campolungo Pass would represent on the east of Sella 
another small sheared fragment below the peripheral overthrust, 
offering complete analogy with the southern dolomitic fragment of 
Sasso Pitschi; and neither of these abrupt summits can be said, 
upon the evidence of stratigraphy, to have arisen as individual coral- 
reefs. 

Peripheral overthrust in the north-eastern part of 
the massive.—Immediately north of the Pian de Sass terrace an | 
escarpment runs eastward from the imposing cliffs of Vallon to the 
grassy col between Corvara and Campolungo. The escarpment 
terminates abruptly against the small peak of Cra di Mont, the 
eastern corner (‘ Cra’) of the Sella Massive. The col below is some- 
times called ‘ Corvara Col,’ and sometimes erroneously ‘ Campolungo 
Pass’ (p. 598). The escarpment is composed of the diagonal anti- 
«line of Schlern-Dolomite rock and Raibl horizons, faulted against 
the downthrown Raibl strata and Dachstein dolomitic limestone 
forming the high cliffs on the west. ‘The strata of the escarpment 
are crumpled and broken at intervals by flexure-faults. One well- 
marked flexure occurs about the middle of the ridge, and bends the 
strata very steeply eastward. Lago di Boe lies in the hollow of that 
flexure, and is surrounded on all sides by Schlern Dolomite be- 
longing to the same overthrust series as that on Pian de Sass. 

Another and more twisted flexure-fault occurs at a lower level. 
In the hollow of it a small wedge of highly-tilted Cassian rock 
occurs, Which can be determined as a high horizon of marls and 
encrinite-limestone. The Schlern-Dolomite peak of Cra 
di Mont crops out below the Cassian wedge, and the 
Schlern-Dolomite strata dip from 35° to 45° westward. 

The position of the Cassian rocks upon the Schlern Dolomite 
indicates the passage of the peripheral overthrust-plane, which 
emerges here as a reversed fault-branch from the diagonal (north- 
north-east by south-south-west) fault between Pian de Sass and the 
Campolungo slopes. The diagonal fault continues its own direction 
below Cra di Mont, and leaves the mountain at this point. It 
penetrates Cassian and Wengen strata in a north-north-easterly 
direction, but soon furcates again, giving off another reversed fault- 
branch in a north-north-westerly direction between the Piz terrace 
and Crap de Sella, and itself continuing in a north-north-easterly 
direction to the Rudort stream opposite Corvara. The diagonal fault 
depresses the western portion, and is recognizable as one of the series 


602 MISS M. M, OGILVIE [MRS.GORDON| oN THE [Aug. 1899, 


of north-north-east and south-south-west faults, with westerly down- 
throw, which mark the east side of Sella. 

The higher reversed fault-branch, above Cra di Mont, may be 
traced as a low overthrust-plane round the curvature of the moun- 
tain as far as Piz Kofl. It represents the return-fold from Sella in 
the south-eastern quarter of the Groderi-Pass torsion-system. The 
thrust-plane separates the outward-dipping Schlern Dolomite of the 
Piz terrace from numerous small twisted segments of the Schlern 
Dolomite and Cassian strata belonging to the underlay of the peri- 
pheral fold. The dip in these segments is always inward, and they - 
correspond to the similar fragments on the Campolungo Pass and 
Corvara Col. It will be objected by some that these segments are 
all landslips and do not permit of a stratigraphical reading. To 
such objections I can only reply that minute investigations on the 
spot will convince an unbiased mind that the ‘slips’ are sheared 
slices through the middle limb and underlay of a twisted fold." 

The lower reversed fault, above Crap de Sella, has a high incli- 
nation and crosses the Gréden Pass almost: vertically in a north-west 
to south-east direction. The summit of Crap de Sella is composed 
of the highest horizons of Cassian strata,—thick-bedded, yellowish 
limestones full of Cidaris-spines and encrinite-stems. A few block- 
remnants of dolomite weathered in situ show that the Cassian Series 
was followed by the conformable succession of Schlern Dolomite. 
Thus the Crap de Sella fault has effected a repetition of Cassian 
strata and Schlern Dolomite at a level of about 250 feet below the 
outcrop of the same horizons of rock on the Piz slopes, and is the 
lowest of the reversed faults on this side of Sella. 

The overlapping of shear-planes in different horizons of the 
crust in the Bova-Alp region, as contrasted with the divergence 

of shear-planes in the Piz region, is a typical torsion-phenomenon, 

and points to relatively stronger oblique compression in the Bova- 
Alp region. It may be compared with the case in the northern 
fold-are of the Buchenstein Valley, where the shear-planes overlap 
in the west and open out in the east of the centre of torsion. 

The steep slopes below the ‘Crap’ present a complex network 
of faults in the Cassian and Wengen strata. The general tendency 
is to buckle up the strata along diverging torsion-curves parallel with 
the curve of the Piz terrace above. The faults are chiefly north- 
and-south, and they meet the main north-north-east and south-south- 
west diagonal fault of the Campolungo Pass. The curve described 
by the course of the Rudort stream precisely po amagye ss with 
the general direction of these torsion-curves. 

The northern and southern fold-arecs in the peri- 
pheral overthrust.—A continuous series of peripheral over- 
thrusts has now been traced completely round the Sella Massive. 


1 The complete form of a torsion-curve is composed of a number of unit- 
shears; a shear in one direction dies out, as a shear in a new direction starts at 
a small angle with the other. Thus a curve of torsion-shears is formed on the 
principle of furcation previously enunciated (p. 581), and the precise angle of 
inclination differs in the several shear-planes. 


= ee ee 


Vol. 55:] TORSION-STRUCIURE CF THE DOLOMITES. 603 


[In all cases overthrust has been outward from the heart of the 
mountain, and has served to neutralize steep inward and downward 
flexures of the strata from the twisted anticlinal buckles which 
surround the synclinal area of the mountain. Hence, no matter 
where .a section is drawn through Sella, the same general lines will be 
obtained in the peripheral fold-form (figs. 15 & 17, pp. 592 & 594). 
The fold-form at once recalls the ‘fan-structure’ of the central 


- massives of the Alps. 


Cassian strata have been frequently carried along the overthrust- 
plane above Schlern Dolomite, while the Schlern Dolomite below 
the overthrust has been variously cut, as a continuous slice of irre- 
gular thickness in the north-west of the mountain, and as sheared 
wedge-shaped fragments at other parts of the periphery. 

The peripheral overthrust-fold subdivides itself naturally into two 
fold-arcs, a northern and a southern, separated by a well-marked 
depression in the massive, from Pian de Sass westward across the 
central area. The northern arc is the wider and larger; it com- 
prises the Meisules torsion-curve round the north-west of Sella, and 
the Piz-terrace torsion-curve round the north-east, overthrust being 
to the north-west and north-east respectively. The strata of the 
underlay thin out southward, in which direction therefore con- 
tinuously lower horizons are sheared against the thrust-plane. The 
Meisules and Piz-terrace curves correspond to the D & C force- 
spirals in the Groden-Pass scheme of torsion. 

The southern fold-are comprises the Pordoi torsion-curve round 
the south-south-west and the Bova-Alp curve round the south- 
south-east. This curve represents the sunken northern fold-are 
corresponding to the A & B force-spirals in the Buchenstein-Valley 
torsion-system. | Overthrust has taken place to the south-south- 
west and south-south-east. The underfolded strata have been 
dragged and sheared into a series of slices thinning out northward, 
and therefore continuously lower horizons occur next the thrust- 
plane as it twists towards Val la Stries and Bova Alp. 

As these peripheral overthrusts have taken place in oblique 
compass-directions, the axis of maximum tension in the rocks com- 
posing the massive is a line dividing the D & A force-spirals on 
the west from the C & B force-spirals on the east. Such an axis 
would run, generally speaking, north and south from the Pissadoi 
Ravine to Monte Forca, immediately east of the Pordoi summits. 
The resultant forces of compression must have acted at right angles 
to this axis (see fig. 19, p. 607). 

Considered from the aspect of the torsion-movements, the Sella 
Massive is a buckle occupying a torsion-basin between the cross- 
anticlines of the Sella Pass and the Campolungo Pass, and is itself 
directed north-north-east and south-south-west. But it occupies a 
synclinal area between the east-and-west anticlines of the Groden 
Pass and of the Belvedere ridge. From this it would seem that 
there has been oblique folding in the Sella Massive, north-north-east 
and south-south-west, as well as meridional folding. These two 
told-axes are denoted by the direction of two chief ravines in the 


604 MISS M. M. OGILVIE [MRS. GORDON| ON THE [Aug. 1899, 


massive, namely, the Pissadoi Ravine, north-north-east and south- 
south-west, and the Val la Stries Ravine, directed east and west. 

Torsion-phenomena on the eastern side.—tThe strike of 
the strata, and the overthrusting in the peripheral fold, curve round 
an eastern arc from the Groden Pass to the Cordevole Valley. The 
actual change of direction takes place at a sharp angle in the neigh- 
bourhood of Pian de Sass, and the influence of conflicting force- 
components at this part so far explains the confused position of the 
rocks. North of Pian de Sass the shear-planes diverge north and 
north-west ; south of Pian de Sass they converge south-west towards 
the Bova Alp. While the overthrusts may be taken in themselves 
as a proof of lateral compression, the curvature of the shear-planes 
is a proof that the lateral compression was combined with horizontal 
torsion. 

Further evidence of the crust-torsion is afforded by the presence 
of vertical faults radiating outward from the inner areas of Sella 
in north-easterly and south-easterly directions, and therefore inter- 
secting the shear-planes. These faults are transverse to the several 
tangential shear-slices which compose the complete torsion-curve, 
and may be termed torsion-radii. 

The chief rock-joints also form a radiating series on the east 
side, radiating to north-east, east, and south-east. They stand 
undoubtedly in torsion-correlation to an opposite series of fissures 
and slight faults which radiate from the higher horizons of Cherz 
Hill to the north-west, west, and south-west, round the Campo- 
lungo curve of the hill. 

The Sella Series and the Cherz Series are separated by the 
Campolungo Fault, which limits the Sella synclinal area on the 
east side. On the downthrow or west side of the fault the Wengen- 
Cassian strata are tilted westward, and the strike is twisted to 
north-west and south-west. On the east or upthrow side there is a 
decided dip-flexure from west (facing Sella) to north-east (facing 
Pralongia), and the strike twists to north-north-east and to east- 
south-east. 

The Campolungo Fault therefore traverses a diagonal anticline 
directed north-north-east and south-south-west, and dividing the 
deep Sella basin from the shallower syncline of Prilongia. The 
diagonal fault is met on the west side by curved torsion-faults from 
the two main east-and-west anticlines on the north and south, and also 
by torsion-radii diverging outward from the adjacent basins. These 
faults and curves are so intimately associated with the diagonal 
anticline that the latter is comprehensible only as the expression 
of a vertical movement contemporaneous with horizontal movements 
of torsion. 

Cleavage-planes penetrate the rocks of the mountain, generally 
speaking, in two directions, north-north-west and south-south-east, 
and north-north-east and south-south-west. Round the eastern 
curve of the mountain, however, the arrangement is specialized in 
accordance with the sharp curvature and strong compression on 
this side. North-and-south cleavage-planes pass through all the 


Vol. 55. | TORSION-STRUCTURE OF THE DOLOMITES, 605 


rocks of the eastern side ; they are intersected by planes at varying 
oblique angles to north-west in the north-eastern curve, and to 
south-west in the south-eastern curve. 

Evidence of a former east-and-west strike.—Minor 
complications are present on the eastern side which bear testimony 
to a pre-existing strike. These are east-and-west, flexures and 
flexure-faults. ‘The Lago di Boe escarpment, in the middle of the 
eastern side, is an upthrow separated from two shelving terraces 
north and south by east-and-west faults. The northern is the Piz 
terrace, with flexure to the Groden Pass; the southern terrace is 
that of Pian de Sass, which is separated from another upthrow, 
namely, that of Col di Stein, by an east-and-west fault parallel with 
those which limit the Lago-di-Boe upthrow. A southerly flexure 
of the strata descends from Col di Stein towards the Buchenstein 
Valley. 

Thus the eastern side, taken from north to south, is composed of 
alternating arches and troughs. Such a series indicates crust- 
folding at some time from north and south. 

The same succession of east-and-west flexures is quite apparent 
throughout the mountain, but the component arches occur at wider 
intervals in the central downthrow of the mountain. Corresponding 
to the Pian-di-Sass trough, a broader trough runs through Vallon 
and the Pizza Longa to the inner basin of the west side of the 
mountain. The arch of the Lago-di-Boe escarpment is continued 
westward through the areas of the Pissadoi and Meisules summits. 
The Col-di-Stein arch, south of Pian de Sass, curves southward 
and runs through the Pordoi and Sella summits. The troughs 
external to these arches are indicated by the outward flexures, but 
the actual hollows of the outer troughs have been covered by tke 
peripheral overthrust. 

There is absolute stratigraphical evidence in all cases that this 
series of east-and-west flexures in Sella Mountain has been broken 
up by the various oblique shear-planes, the radiating faults and 
joints, and the cross-cleavages which I group together under the 
name of torsion-phenomena. Therefore we have to bear in 
mind that the forces which induced these phenomena had an already 
folded crust to work upon. 

Stratigraphy at the Boe summit.—There is still the 
highest terrain of the Sella Massive to be discussed, which should, 
according to Mojsisovies’s description in his ‘ Dolomit-Riffe,’ be 
wholly occupied by ‘Dachstein Limestone.’ That is, however, not the 
case, as | showed in my paper in the Geological Magazine for 1894. 

Ascending to the Boe summit from Val la Stries, the Dachstein 
horizon is met at a lower level than that mentioned by Mojsisovics. 
Abundant specimens of Megalodon triqueter were found by me 
in the rock at the 2600-metre contour-line. The strike was 
north-west and south-east, the dip very slight, about 8° or 10° 
towards the summit. Already from that horizon the eye was 
attracted by the appearance of bright, brick-red, earthy strata on 
the north side of the Boe summit. Viewed from a distance they 


“ 


606 MISS M. M, OGILVIE [MRS. GORDON] on THE  [ Aug. 1899, 


seemed to rest conformably upon the Dachstein Limestone of the 
western side, and it was difficult to think how Dachstein Limestone 
could form the highest summit. Nearer investigation brought out 
rather complicated relations, Dachstein Limestone in its highest 
fossiliferous horizons forms the Boe summit. It is part of an 
overcast fold from the south and south-east, with the C-shaped 
curvature towards the north and north-west, while the brick-red 
earthy strata are part of an attenuated and sheared series of 
Jurassic rocks which lie in the trough of the overfold (fig. 18). 


Fig. 18.—JInfold of Jurassic rocks, viewed from the east, and 
showing the compression and shearing of the strata. 


| Jur = Jurassic. 


The Jurassic infold is favourably exposed for examination. The 
Val la Stries or western aspect is at once the simplest and the 
most complete. The various horizons of Jurassic rock are found to 
be stretched, and therefore thinned, from north to south along a 
shear-plane of Dachstein Limestone. Thus, Liassic rocks occupy 
the terrain partially covered by the Pissadoi Glacier, while the 
younger brick-red marls (Fleckenmergel) and nodular shales 
and limestones of higher Jurassic horizons occur nearer the Boe 
summit. Maploceras Stazyczi (Geuschn.) was met with in the higher 
‘horizons. The fossils found in the Liassic limestone-rocks were 
numerous, but badly preserved, chiefly ammonites belonging to 
the Aygoceras angulatum-zone. The shear-surface of the Dach- 
stein rock is undulating, and is penetrated by several vertical 
chasms, some of which have undoubtedly a structural import. 

A well-marked fissure separates the Dachstein-rocks of the Boe 
summit from the contorted Jurassic marls immediately north of it. 
The fissure denotes the reverse plane of movement with downthrow 
on the side of the marls. Radial dislocations penetrate the infolded 
strata, radiating westward. These meet the reversed fault of the 
Boe summit in a basin of Dachstein strata on the east side of the 
ridge. ‘The basin is occupied by a small lake, the Eis See. 

Just as in the case of intersection of a shear-plane at the Bova 
Alp, the plane of the overthrust undergoes a sharp curvature at the 
point of intersection, and is twisted almost due north, slightly north- 
north-east. The reverse plane becomes then almost vertical, and 
faults Dachstein Dolomite against Liassic and other Jurassic strata. 
The Jurassic strata thin out from west to south, where the radiating 
faults diverge, but are strongly crumpled and compressed on the 
east, where the faults converge. The radiating faults through 


Vol. 55.] TORSION-STRUCTURE OF THE DOLOMITES. 607 


them are radii to the western curve limiting the outcrop of the 
Jurassic strata, a curve parallel with the torsion-curve round the 
western periphery of the mountain (see Pl. XL). 

A diagonal buckle, directed north-north-east, extends from the 
Boe summit towards the Eis See summit, and is composed of His 
highest horizons of the Dachstein Series. The summit-buckle 
which is fractured lengthways, with downthrow to the west, is aver 
thrusteastward and ‘ i 
southward upon Fig. 19.—Diagram of torsion at the 
the main mass of Boe summit. 

Dachstein Dolomite 
forming the eastern 
part of Sella. 

The occurrence of 
Jurassic strata west 
of the summit- 
buckle is highly 
significant. It is 
demonstrative of a 
central subsidence- 
area within the 
wider subsidence- 
area occupied by 
the whole massive. 
The highest strata 
may besaid to have 
collapsed into the 
space afforded cen- 
trally as a result of 
the outthrust and 
overthrust of the 


rocks of the massive 
all round the peri- [The general outline of the summit-buckle and over- 


phery. This phe- ree is shown by strong broken lines. The 
eavy arrows represent the evoiute movements of 

nomenon confirms the overlay, the dotted arrows represent the invo- 

the correctness of lute movements of the underlay. ] 

the observations al- ff=Radial faults. H.=Bamberg shelter-hut 

ready detailed. The (Alpine Club). 


Jurassic strata are, 

moreover, present in a trough directed north-north-east and south- 
south-west, parallel with the leading diagonal buckles in the Sella 
area. 

The summit-buckle is parallel with the two buckles on the eastern 
side which have been already discussed. namely, the diagonal 
anticline exposed in Raibl and Schlern-Dolomite rocks north-north- 
east and south-south-west through the mountain from the Piz ter- 
race to the Bova Alp, and the diagonal anticline which runs across 
the Campolungo Pass exposed in Wengen-Cassian strata. Both of 
these lower anticlines, as well as the summit-buckle, are traversed 
by diagonal faults, with downthrow to the west. 


608 MISS M. M. OGILVIE [MRS. GORDON] on THE _[ Aug. 1899, 


Evolute and involute torsion-movements at the 
summit.—The Jurassic strata have subsided upon a sliding- 
plane and have been twisted south-eastward in proportion as the 
underlying Dachstein-rocks have been in their main body over- 
thrust to the north-west towards the periphery, and in smaller 
mass twisted south-eastward along with the Jurassic strata. At the 
same time the Dachstein rocks of Vallon below the His-See summit 
have been twisted south-westward, a movement precisely the converse 
of that which has taken place in the higher rocks between the Boe - 
and Kis-See summits. This movement round the Eis-See summit 
repeats the C-spiral movement characteristic of the south-eastern 
quarter in the Groéden-Pass scheme, while the movement in the 
Jurassic infold and Boe ridge repeats the movement of the D-spiral 
in the south-western quarter of the Groden-Pass scheme. 

The southern part of the summit-buckle is overthrust round a 
small southern fold-are parallel with the Pordoi and Bova-Alp 
fold-arc in the southern periphery of the mountain. The underlay 
of the Dachstein-rock has been tilted inward and sliced northward, 
while the overlay has been thinned towards the south-west and 
south-east. These complex movements repeat the A & B spiral 
movements already demonstrated in the southern part of the peri- 
pheral overthrust. (See fig. 19, p. 607.) 

The similar appearance presented by the curved masses of 
calcareo-dolomitic strata at Sasso Pitschi and the southern part of the 
Boe summit-ridge is therefore no chance resemblance, but a result 
of precisely similar crust-torsion at the one place and at the other. 

The same spiral directions of twisting movement, therefore, 

explain the position of the strata in the main mass of the mountain 
and in the summit-area. Centrifugal forces have pushed outward 
-and upward the Dachstein horizons of the summit-buckle, while 
centripetal forces have pressed inward and tilted downward the 
Dachstein and Jurassic horizons of the summit-trough. Thus crust- 
movements which may be termed ‘evolute’ and ‘involute’ have 
taken place in reference to a central area upon which the Eis See 
rests. The lake-area is that in which radiating faults converge, 
and apparently denotes the superposition of a diagonal arch upon 
an earlier east-and-west arch. 

Fan-structure.—The Dachstein buckle on the top of Sella 
affords a miniature example of Alpine fan-structure. It rises from 
the midst of a circumferential trough much elongated in shape. 
The fundamental fact is that its position here is the result of 
combined translatory and rotatory movements. The 
older rocks have been twined above younger horizons. 

In the same way the peripheral overthrust-rocks of the Sella 
Massive have been twined in different directions outward and 
upward relatively to inward and downward flexures of younger 
strata. These flexures represent the synclinal curves corresponding 
to anticlinal curves round the mountain. Hence the mass of rocks 
composing the overlay of the peripheral overthrust rises from a 
circumferential trough proportionately larger than the trough below 


Vole55=| TORSION-STRUCTURE OF THE DOLOMITES. 609 


the summit-buckle, but similarly elongated in shape with reference 
to a north-north-easterly and south-south-westerly axis. 

The mountain-massive of Sella may be described as an elliptical 
basin or sag. 

Rock-twining and dolomitization.—The main body of 
Dachstein-Raibl-Schlern-Dolomite rocks is disposed as an elliptical 
‘tier’ of rock which may be termed a rock-whorl. In each 
part of the whorl corresponding to an individual spiral movement 
the upper horizons of the whorl have been twisted and bent in 
opposite directions from the lower horizons. The mass has 
therefore undergone twining-strains to a very great 
degree. The lines dividing parts of the rock-whorl which move 
in opposite directions are ‘nodal lines’ in respect of the crust- 
movements. Dynamo-metamorphic changes undoubtedly have taken 
place in rocks undergoing such powerful strains, and the processes 
which brought about the dolomitization of the ‘ Dachstein’ and 
‘Schlern’ calcareous masses may have been directed or greatly 
aided by these torsion-strains. 


Fig. 20.—The Sella folds, before and after torsion. 
N. S. 


2a ga 4a 4b 5a 


\ 


? 
Se t ee 


Character of the two movements.—tThe effect of the earlier 
movement has been described above as a simple wrinkling of the 
crust into a series of folds with east-and-west strike (p. 605). 

I have distinguished five folds in the region examined :— 


1 (a) Grdden-Pass arch; (0) Groden-Pass trough, now involved in the 
thrust-plane of the northern fold-are of the Sella Massive. 

2 (a) Arch of Meisules-Pissadoi-Zehner summits and the Lago di Boe 
escarpment ; (0) corresponding trough through the heart of the 
mountain, including the Jurassic infold. 

3 (a) Boe summit ; (0) trough between Boe and Pordoi. 

4 (a) Arch of Sell ae -Pordoi- Col di Stein summits; (5) southern trough, 
including Val la Stries, Monte Forca, Bova Alp. 

5 (a) Cima-di-Rossi portion of the Belvedere-Buchenstein arch. 


The later movement was locally one of compression from west- 
north-westerly and east-south-easterly directions. Had there been 
no previous folds the result would presumably have been the for- 
mation of crust-folds directed north-north-east and south-south-west. 


e726. 8. No, 219. 2B 


610 MISS M. M. OGILVIE [MRS. GORDON] ON THE  [ Aug. 1899, 


Distorted folds in that direction can be traced upon the basis of 
dip-flexures as follows :— 

1 (a) Sella-Pass arch; (6) Ciavatzes trough and the underthrust on the 
western side. 

2 (a) Arch of the Meisules terrace in the direction from the Meisules to 
the Sella summits ; (4) parallel inward flexure towards the centre. 

3 (a) Pissadoi and Pordoi arch crossing the centre in the neighbourhood 
of the shelter-hut ; (0) diagonal central trough (Jurassic inthrow). 

4 (a) Arch from the Hissee summit to the Boe summit; (0) trough from 
the Vallon downthrow inward to the summit-ridge. 

5 (a) Arch of the eastern side; (6) trough mostly concealed in the under- 
thrust, inward flexures apparent at Cra di Mont and the Campo- 
lungo Pass. 

6 (a) Main arch across Campolungo. 


It is quite in accordance with our knowledge of crust-movement 
that a crumpling and contraction of the crust from east and west 
should succeed a crumpling and contraction from north. and south. 
The whole interest lies in the investigation of the details; in 
determining firstly, which was the earlier of the movements in any 
given area; secondly, how far the late movements were modified by 
the pre-existing crust-folds. 

What actually took place in the Enneberg area during the later 
movement was the subsidence of elliptical areas of the 
crust, associated with converse torsion-movements in 
different horizons of the crust. In the areas of sub- 
sidence, crust-whorl above crust-whorl was arranged 
in tighter and more contracted positions than would 
have been possible without torsion-movements, 

Torsion-buckles.—The presumptive geographical direction 
and particular local position that would have been assumed by dia- 
gonal folds if the crust had been more mobile have been determined 
by the writer not only upon the basis of dip-flexures and diagonal 
faults parallel with them, but also upon the evidence of series 
of torsion-buckles. These buckles are distorted periclinal bulgings 
of the crust at places where diagonal arches of the later movement 
have interfered with and crossed arches of the earlier movement. 
The maximum torsion-effects are apparent in the crossing of the 
chief anticlines in the older system, namely, those of the Gréden Pass 
and Belvedere-Buchenstein. The bulgings are typically lozenge- 
shaped in ground-plan, with a longer axis in some oblique east-and- 
west direction, and a short axis in some oblique north-and-south 
direction, but not rectangular to the other. 

As an example, take the torsion-buckle at Plon, on the west of 
the Groden Pass (see map, Pl. XL). The diagonal north-north-east 
and south-south-west arch across the Sella Pass has intersected 
there the Gréden-Pass Anticline, and the effect has been the de- 
termination of a local centre of crust-weakness and cross-ruptures. 
The chief crust-rupture has occurred along (a) the west side of the 
diagonal arch, and is marked by an intrusive dyke. (6) Oblique 
torsion-faults are associated with the chief ruptures ; they form 
two opposite virgating bundles, the one converging eastward 


Wolss5- | TORSLON-STRUCTURE OF THE DOLOMITES. 611 


towards the height of the Groden Pass, the other converging west- 
ward round the Champinoislopes below Lang Kofl. (c}) Intrusive 
sills penetrate the fault-planes in the opposite bundles, and are 
continuous with the cross-dyke. The sill-intrusions are pre- 
dominant in the inclined planes hading north in the Vallbach area 
of downthrow towards the Spitz Kofl group north of the Groden Pass, 
and in the inclined planes hading south in the Champinoi area of 
downthrow towards the Lang Kofl group on the west side of the 
cross-arch. (d@) The cross-axes of the buckle are directed east-north 
east and west-south-west (from the Groden-Pass apex of virgating 
faults to the Lang-Kofi apex), and north and south. Another 
example of a torsion cross-buckle occurs at Pescosta. 

Owing to the inelastic nature of the crust, deformation of the 
east-and-west folds was the essential condition upon which new 
crust-forms could be carried out. The virgating fault-curves which 
turn away from the cross-buckles on all sides show that these 
areas were individual centres of evolute movements in 
deep layers of the crust. The term ‘evolute’ has special 
reference to a compensating ‘involute’ movement (p. 608). The 
intrusion of igneous rock into the cross-buckle shows that the 
molten layers below the crust had involute movement towards 
such centres. The greater the compression at any given area, the 
wider would the buckle become and the greater would be the mass 
of intruded rock. 

The northern synclinal curves of Sella have reference to these two 
eross-buckles on the Groden-Pass Anticline; while the southern 
synclinal curves of Sella have reference to two other cross-buckles 
formed at the areas where the same diagonal anticlines (Sella 
Pass and Campolungo Pass) have been superposed on the Belvedere- 
Buchenstein Anticline. 

A general law may be thus stated:—The chief torsion-buckles 
in a system of torsion-folds are formed where the cross-anticlines 
are superposed upon main anticlines of the pre-existing series of 
erust-folds; such areas of superposition are of necessity major 
centres of crust-weakness, peculiarly liable to invasions of molten 
rock during the active period of crust-torsion. 

Torsion as affected by, and affecting, petrographical 
conditions.—All round Sella the Wengen-Cassian Series has been 
let down by faults from the anticlinal cross-buckles, and has been at 
the same time twisted downward into the underlay of the peripheral 
overthrust of the massive. ‘The series has therefore sunk relatively 
to both the great masses of calcareous rock—Middle Triassic lime- 
stones below and Upper Triassic limestones above. The intermediate 
Wengen-Cassian Series would inevitably have been buried at some 
parts had the twisting and compression been greater (see fig. 20, 

. 609). 
5 ee tice danger threatened the mixed series of Jurassic strata, 
comprising marls, breccias, and thin nodular limestones. They 
were bent inward and twisted downward beneath portions of 


Dachstein Limestone moving outward and upward. Curious 
2m 2 


612 MISS M, M. OGILVIE [MRS. GORDON] oN THE  [ Aug. 1899, 


variations in thickness were effected, both in the case of the Wengen- 
Cassian Series and the Jurassic rocks. Such appearances have been 
attributed to natural causes—ground-inequalities during deposition, 
coral-growth, etc.; but any striking cases observed at Sella are 
results of the complex shearing movements during crust-torsion and 
compression. 

While the crust-strains can be always demonstrated in the 
fragmental rocks by means of the contorted and fractured strata, 
less stratigraphical disturbance is visible in the calcareous horizons. 
Sufficient proof, however, of crust-strains through the calcareous 
rocks is presented by the significant fact of their dolomitization. It 
may be added that the earthy Raibl strata which occur beween the 
two calcareous horizons of Upper Trias very frequently show 
contortions and fractures when the calcareous horizons seem com- 
paratively little disturbed. 

Strike-torsion.—The fault-blocks composed of the ical 
geological horizons and extending between the old anticlines and 
the later diagonal anticlines have a small torsion-angle relative to 
the original strike. For example, taking the D-quarter of the 
Groden Pass as a type (Pl. XL), we find that the Muschelkalk block 
of Pitzculatsch Hill has a torsion-angle of strike of about 20°, while 
the Upper Triassic rocks in the massive have a greater torsion-angle, 
about 35° to 40°. It is only in the highest horizons that the 
strike-torsion has reached an angle of 50° to 70°. 

The Groden-Pass scheme will show how two cross-directions of 
strike are always co-ordinated as a necessary result of the action of 
the torsion-forces. A west-south-west and east-north-east strike at 
one part of a torsion-curve is responded to by a west-north-west and 
east-south-east strike in the other part of the curve; similarly, a 
south-west and north-east strike is responded to by a north-west and 
south-east strike in the other portion, and a south-south-west and 
north-north-east strike is co-ordinated with a north-north-west and 
south-south-east strike. 

Summary.—Briefly summarizing, we note that 


(1) The synclinal basin of Sella is included within a polygon of faults whose 
planes incline inward. 

(2) Steep downthrow-faults or flexures from the surrounding anticlines are 
neutralized by peripheral overthrusts from the synclinal basin. ‘The Wengen- 
Cassian Series is sunk, strongly contorted and mutilated between these 
corresponding faults round the massive. 

(3) Torsion has taken place in different directions in the overlay and underlay 
of the peripheral overthrust. 

(4) The same horizons of Dachstein strata that bend outward in the peri- 
pheral overthrust bend inward to form the underlay of a summit-overthrust, 
but the underlay has been twisted in opposite directions from the twisting in 
the overlay. The overlay of the summit-overthrust repeats the same directions 
of twist as the overlay of the peripheral overthrusts. 

(5) Thus the Upper Trias of the massive is arranged i in two whorls, as a 
result of combined movements of torsion and compression. 

(6) The Lower and Middle Triassic strata are heaped up in torsion-buckles 
situated at the four oblique corners of the massive: Plon, Pescosta, Arabba, 
and Rodella. These have been local centres of eruption during torsion- 
movements. 


Wolkes5./ TORSION-STRUCTIURE OF THE DOLOMITES. 613 


V. Serr Sass AnD PRALONGIA. 


The Sett-Sass and Prailongia area a companion to 
the Sella Syncline.—The Dolomite-mountain of Sett Sass, 
together with the meadows of Pralongia and Stuores, form a 
broken-up synclinal area on the southern side of the Langs-da-Fur 
Anticline and on the northern side of the Buchenstein Anticline. 
The diagonal buckle of the Campolungo Pass extends from the Groden 
Pass to the Buchenstein Anticline, and separates the Sett Sass and 
Pralongia Syncline from the companion syncline of Sella. 

On the western side of the diagonal buckle three parallel faults 
have already been traced in a north-north-easterly and south-south- 
westerly direction, all having downthrow to the west, and therefore 
lowering continuously younger rocks towards the central depression 
of the Sella Massive (pp. 590 & 604). My earlier work showed that 
the Pralongia ridge was cut by faults with downthrow to the east, 
that is, towards Sett Sass; only one fault was traced on the west 
side of the Prilongia ridge with downthrow to the west.’ 

Eastern flexure-fault of the Campolungo- Pass 
Anticline.—The subsequent examination of the Buchenstein 
Valley has disclosed the southerly continuation of these cross-faults 
penetrating the Pralongia ridge. The diagonal fault between 
Pralongia and the Ruones slopes is parallel with the Campolungo 
and Pian-de-Sass Faults. It continues with the same north-north- 
easterly and south-south-westerly direction through the buckled-up 
Wengen rocks of the Cherz and Campolungo slopes. It separates 
two general strike-systems in the rocks of Cherz Hill, the fault- 
block on the west side having a north-easterly and south-westerly 
strike and dip to north-west, the other on the east side of the fault 
having a north-westerly and south-easterly strike and dip towards 
the north-east. The fault may be said to cut off the east-and-west 
Varda overthrusts on its east side from the Muschelkalk, augite- 
porphyrite, and Wengen rocks composing the diagonal fault-block 
of the Campolungo Pass. This fault passes through the steep flexure 
of the rocks from the diagonal arch of the Campolungo Pass towards 
the Selvaza and Ruones hollows on the east side. 

The oblique torsion-faults which slice the Varda overthrusts round 
the south-west of Cherz Hill meet the north-north-east and south- 
south-west Campolungo Fault. It is impossible to trace these oblique 
torsion-faults northward through the Wengen rocks of Cherz Hill, 
as these are largely grass-grown. But it may be noted that a con- 
tinuation in that direction would mean a general convergence of the 
fault-lines towards the Selvaza hollow. All the exposures of Wengen 
strata which can be found on the Selvaza slopes show considerable 
contortions in the rocks, and prove strong compression. 

These features indicate a radiating bundle of small oblique torsion- 
faults through the curved overthrusts round the south-west of Cherz 
Hill. The correlation of these torsion-fault curves and radii with the 


> Quart. Journ. Geol. Soe. vol. xlix (1893) p. 18 & map A. 


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Wolke 51 THE TORSION-STRUCTURE OF THE DOLOMITES. 615 


converse curves and oppositely radiating faults on the eastern side 
of Sella has been pointed out above (p. 604). 

Pralongia Fault.—The next diagonal fault that I determined 
on the Pralongia ridge is the Pralongia Fault, which divides a 
central portion of the ridge, including the highest point (2182 metres), 
from a western wing, where a cross stands upon a slightly lower 
summit (2141 metres). The western wing is thrown down, and 
large blocks and standing pieces of the highest thickly-bedded 
Cassian limestones are preserved on it; whereas the fossiliferous 
marls representing an older paleontological zone than these limestones 
are exposed on the high central segments at Stuores. 

This Prailongia Fault may be traced northward along a line of 
landslips as far as Corisell on the right bank of the Sore stream. 
There it meets the eastern extremity of the southerly limiting-fault 
of the Groden-Pass Anticline. Traced southward, the Pralongia 
Fault causes marked disturbance in the strata of the southern 
slopes at the 2000-metre and 1900-metre contour-lines. It is 
continued through the overthrusts of Cherz Hill and across the 
Buchenstein Valley to the Soraruaz area, whence it curves towards 
Sasso di Mezzodi. This fault throughout has a downthrow to the 
west. 

Stuores bundle of diagonal faults.—Another diagonal 
fault cuts the Prilongia ridge, separating the central part with 
its summit at 2182 metres from an eastern wing with its summit 
at 2172 metres. Downthrow is to the east; hence the central 
part of the Pralongia ridge corresponds to a diagonal 
north-north-east and south-south-west arch with 
flexure-faults on the opposite sides. This fault is a 
branch from the more important diagonal fault which limits the 
Stuores meadows against the western side of Sett Sass, with con- 
siderable downthrow to the east. Between these two faults others 
are present with similar effect, converging towards the north of 
the Stuores meadows. The bundle of Stuores faults intersects the 
southern overthrusts, and the latter curve at the area of intersection 
from a west-north-westerly and east-south-easterly to a west-south- 
westerly and east-north-easterly direction. The analogy between 
the Stuores bundle and the Bova-Alp bundle of diagonal faults 
(p. 604) will be at once apparent. 

The chief fault of the bundle between Stuores and Sett Sass 
is continued northward along the western side of the Kreuz-Kofl 
dolomite-mountains.. The main Stuores Fault marks as great a 
downthrow of the strata on the east side of the Prilongia meadows 
as that which has taken place on the west side, where a west-south- 
west and east-north-east curved torsion-fault limits the Langs- 
da-Fiir Anticline against the syncline of Siadu, and in both cases 
the downthrow is eastward. 

These two faults form the two sides of a triangle whose wide base 
is formed by the uptilted Wengen strata of Campolungo and Cherz 


1 See my paper in Quart. Journ. Geol. Soc. vol. xlix (1893) pp. 64-66, and 
Rothpletz, ‘ Geol. Querschnitt durch die Ost-Alpen,’ 1894, p. 57. 


616 MISS M. M. OGILVIE [MRS. GORDON] ON THE [ Aug. 1899, 


Hill. The three faults across the Priilongia ridge diverge at almost 
equal distances one from another within the triangle, and demon- 
strate alternate cross-buckling and depression of the strata entirely 
analogous to that observed on the east side of Sella; but here the 
general downthrow is eastward, while at Sella it is westward. The 
base of the triangle is an anticlinal curve round the south-west, 
towards which direction the diagonal faults of Prilongia diverge. 

Strike-torsion round Pralongia and Sett Sass.—The 
wide triangular exposure of Cassian strata at Prilongia is cha- 
racterized on the south side by a torsion of the strata from a 
north-easterly and south-westerly strike at Monte Sief, an easterly 
and westerly direction of strike on the Selvaza slopes, to a northerly 
and southerly direction of strike on the Ruones slopes; on the 
north side, by a torsion of the strata from a west-north-westerly 
and east-south-easterly direction at Hisenofen, and an east-north- 
easterly and west-south-westerly direction in the lower slopes 
between the Piccol and Stuores streams, to a northerly avd southerly 
direction in the upper Piccol slopes. 

Thus two torsion-ares limit the shallow syncline of the Pralongia 
meadows—=2 northern arc from Ruones to the lower Piccol district, 
and a southern are from Corvara round Cherz Hill to Monte Sief. 
As in the case of the Sella syncline, D & C spiral movements have 
been followed in the northern arc, and A & B spiral movements 
through the southern arc. But whereas the northern arc and the 
associated torsion-movements form the greater part of Sella, it is 
‘the southern are which is the larger round Pralongia and Sett Sass, 
so that torsion-curves corresponding with the A & B spiral move- 
ments predominate in this area (see fig. 8, p. 581). 

Northward continuation of the diagonal Campo- 
lungo Anticline.—Although the Langs-da-Fiir Anticline crosses 
the Prilongia system between Corvara and St. Cassian, it is evident 
that the north-north-easterly and south-south-westerly strike con- 
tinues down the Abtey Valley, and that Campolungo and Abtey 
form a main diagonal anticlinal buckle between two opposite 
synclinal areas occupied by Dolomite-massives.' Pralongia was 
part of a long syncline limited north and south by two earlier 
east-and-west anticlines (Langs-da-Fur and Buchenstein) and after- 
wards crossed obliquely by the superposed anticline of the Campo- 
lungo Pass. ‘Torsion-curves pass from the east-and-west anticlines 
towards the north-north-east and south-south-west anticlines. 

Relation of the Sett-Sass Syncline to Prilongia.— 
Minor complications within the Pralongia Syncline have arisen, 
owing to the presence of another diagonal anticline, namely that of 
Priilongia, parallel with the Campolungo Anticline. This cross-arch 
has broken up the original syncline into two troughs, of which that 
occupied by Sett Sass is the deeper. Again, in the Sett-Sass 
Syncline another cross-arch is apparent, parallel with those of 
Prilongia and Campolungo. It forms that part of Sett Sass which 


" Quart. Journ. Geol. Soe. vol. xlix (1893) p. 27 & fig. 4. 


Vol. 55. TORSION-STRUCTURE OF THE DOLOMITES. 617 


includes the south-western summit (2434 metres) and is continued 
northward to the Eisenofen huts. Flexure-faults directed north- 
north-eastward and south-south-westward are again present—the 
western with downthrow to the west, the eastern with downthrow 
to the east. The most deeply sunk part of Sett Sass is the western 
wing, which is wedged between the diagonal arches of Prilongia 
and Kisenofen. 

Relation of the Sett-Sass Syncline to the Buchen- 
stein Anticline.—Sett Sass represents a synclinal basin as deep 
as that of Sella, and, like it, bounded by a polygon of faults with 
downthrow to the mountain. As the map (Pl. XL) shows, Monte 
Sief and Col di Lana are at the east-north-eastern end of the twisted 
Belvedere-Buchenstein Anticline, while Cima di Rossi is at the west- 
south-western end. <A steep northward flexure of the strata marks 
the whole northern face of this anticline. 

In its proximity to this anticline on its south side, and in its 
downthrow from the Cassian strata of Prilongia, Sett Sass offers a 
precise analogy with the conditions affecting the south and east of 
the Sella Massive. The resemblance became evident to me while 
engaged in mapping the area of Sasso Pitschi, Pordoi Pass, and 
Pian de Sass; and it suggested a clearer interpretation of the 
geology of Sett Sass than had occurred to me from my more limited 
standpoint of 1892. 

The writer’s map* was reduced from the original survey, and 
several of the details were omitted for the sake of clearness in the 
reduced map. The accompanying map of the west and south sides 
of Sett Sass is therefore given, with all the details as originally 


entered on the Survey map on the scale of sam CEE): 


Peripheral overthrust round the southern curve of 
Sett Sass.—The chief feature of the south side is the rock which 
was called ‘ Richthofen Riff’ by Mojsisovics and portrayed by him in 
an excellent photograph.” This so-called reef may be explained 
in precisely the same way as the present writer explained Sasso 
Pitschi,* namely as a slice of Schlern Dolomite below an overthrust- 
plane. 

Careful collection of the fossils in the Cassian marls overlying 
the Richthofen Reef, and as careful comparison of these with the 
fossils found in the Cassian marls below the Reef and upon 
Prilongia and Stuores meadows, made it impossible to determine 
any zonal distinction. In short, the Cassian marls above and below 
the Richthofen Reef are identical both in respect of their fauna and 
their petrographical character. 

With regard to the relations of strike and dip, these vary con- 
siderably when they are followed round the southern curve of the 
mountain. The Schlern-Dolomite rocks of Sett Sass strike east and 
west, and dip 12° northward. The Cassian strata dip regularly below 


1 Quart. Journ. Geol. Soc. vol. xlix (1893), map A. 
2 « Dolomit-Riffe,’ 1879, p. 248. 
3 «Coral in the Dolomites,’ Geol. Mag. 1894, p. 53. 


618 MISS M. M. OGILVIE [MRS. GORDON] oN THE  [ Aug. 1899, 


Sett Sass, but assume irregular relations with respect 
to the Richthofen Reef. Thestrike-readings are north 45° west 
above the Richthofen Reef, veering to north 60° west a little 
eastward, and to east and west still farther east. The dip varies 
from 25° northward above the Richthofen Reef to 60° farther east ; 
and still farther east the strata are tilted almost vertically. The 
Schlern-Dolomite rock of the Richthofen Reef is really at a higher 
level than that occupied by the Cassian strata in the col between 
the Reef and Sett Sass. Such rapid variation along the plane 
between the Cassian strata and the underlying Schlern Dolomite 
would in itself suggest some stratigraphical disturbance of the 
nature of a thrust-plane. 

‘ Dolomite ’-rock forms only the upper half of the Reef, and 
very rapidly thins out eastward. The lower half of the Reef is 
separated from the upper half by an inclined joint- 
plane. The lower half consists of the brownish-yellow limestones 
which mark the uppermost horizons of Cassian rocks all round 
Sella, at Crap de Sella, on Prialongia, and elsewhere. 

Another joint separates this lower half of the Reef-rock from a 
thin basal grey limestone. I followed all three horizons of the 
reef both eastward and westward, and found that soft Cassian 
marls gradually appeared along the continuation of 
these inclined ‘joints’; I regard the inclined joints 
as subordinate shear-planes associated with a main over- 
thrust-plane above the Richthofen Reef, upon which the fossiliferous 
soft- bedded Cassian marls have been overthrust southward above the 
higher horizons of Cassian limestone at some points, and for the most 
part, and above Schlern Dolomite at the Richthofen Reef. 

The map (Pl. XL) and section (fig. 10, p. 586) perhaps explain the 
relations better than a verbal description. Combined with the 
overthrust there has been a differential twining movement in the 
sense of the B-spiral. The overlay of the fold has been twisted 
south-eastward, while the underlay has been twisted north-westward. 
The easterly shear-faults denote segmentation of the underlay due 
to torsion. 

Peripheral overthrust round the west of Sett Sass. 
—A curvature of the peripheral overthrusts takes place where the 
diagonal Hisenofen arch (p. 617) crosses the overthrust. The mode 
of torsion of a thrust-plane under such conditions has been demon- 
strated already in several cases. Here torsion of the strike of the 
strata has been effected from east and west on the south to north-west 
and south-east on the west, while the shear-faults run north and 
south. 

A series of narrow ridges diverge from the diagonal fault on the 
west side of the Hisenofen arch. They radiate from the curvature 
of the cliffs westward and north-westward, and are composed of 
Raibl strata, massive Dachstein-Limestone blocks, and, in less 
number, Schlern-Dolomite blocks. The Raibl rocks are clearly in 
their true position, as they may be followed at about the same level 
along the base of the western cliffs. The Dolomite-blocks are 
largely fallen masses. 


Viol.55-| TORSION-STRUCTURE OF THE DOLOMITES. 619 


Cassian strata are present round the base of the mountain above 
the level of these ridges, and a good exposure is met with farther 
north above a steep crag of Dachstein Limestone in its true position 
with Raibl strata at its base. This exposure proves the peripheral 
overthrust at the west side; it occurs at about the 2250-metre 
contour-line, about midway between the two western summits 
marked 2334 and 2434 metres in the map. Subordinate shears 
also pass through this part of the peripheral overthrust, and may 
be traced to the divergent series of ridges at the angle of curvature 
or south-western corner of the mountain. 

The presence of Cassian strata above successively 
higher horizons of Upper Trias from south to north 
proves how strong the shearing has been in the underlay of the 
peripheral folds. The effect is one which can be explained only on 
the basis of differential twists in the overlay and underlay of a fold 
—the overlay having been twisted south-westward while it was 
thrust outward, and the underlay having been tilted steeply with 
easterly dip and simultaneously twisted north-eastward. Thus 
continuously higher horizons of the underlay would be brought at 
the shear-plane into contact with continuously lower horizons of the 
overlay. 

Although the rocks succeeding the Cassian strata above the 
shear-plane are less disturbed than those below, they show strong 
compression and the thinning-out of the various horizons along the 
shear-plane. Schlern Dolomite represents a small wedge between 
Raibl strata above and below. The Raibl strata below occur in 
bedded fragments, of various horizons, much as in the case of Pian 
de Sass (p.597). The strata comprise (a) sandstones with Myophoria 
Keferstemu ; (6) red and violet marls ; (c) pale dolomitic sandstones 
and breccias; (d) red, violet, and greenish marls and dolomitic 
flagstones. ‘The usual opinion about the western face of Sett Sass 
is that the rocks are mostly rock-slips and screes, with the ex- 
ception of the succession of Raibl strata just quoted and the 
Dachstein Limestone above it. 

I have devoted several days of toilsome work to the ‘screes’ 
and ‘slips,’ and have seen in many places clear evidence that the 
strata had been primarily sheared and twisted into their present 
position. Small surface-slips have taken place along original lines 
of fault-shear, but this is a feature characteristic of the whole 
district, and merely demonstrates adjustment along the lines of 
weakness. 

Pralongia and Castello thrust-plane.—tThe exposure of 
Cassian strata on the Montagna della Corte Pass, between the two 
summits of Richthofen Riff and Monte Sief, shows another repetition 
of the fossiliferous marly horizons and succeeding Cidaris-lime- 
stones. This subordinate thrust-plane may be traced eastward 
towards Castello along a ridge of block-scree which is chiefly com- 
posed of shear-fragments of Cassian strata and Schlern Dolomite 
weathered a situ. The fault-plane passes east-north-eastward 
through the meadows, as far as the transverse fault of the Val- 
parola stream. The Valparola Fault is a westerly one limiting 


620 MISS M. M. OGILVIE [MRS. GORDON] ON THE  [ Aug. 1899, 


another diagonal arch, that of Lagazuoi and Sasso di Stria, parallel 
with the Sett-Sass and Prialongia diagonal arches. 

Westward from Montagna della Corte, the lower thrust-plane 
may be traced through the southern slopes of Prilongia. A wedge 
of dolomitic limestone is again present at about the 1950- and 
2000-metre contour-lines immediately south of the Prilongia 
summit, and is here associated with an intrusive sill of porphyrite. 
The fault-plane curves sharply northward through the Ruones 
meadows, still accompanied by the intrusive sill, and gradually 
assumes a higher angle of inclination (70° to 80°). Its further 
continuation is round a north-western arc between Langs-da-Fir | 
and Siadu, with downthrow to Siadu. The intrusive sill round 
Prilongia is therefore a thread from the Pescosta and Langs-da-Fur 
intrusive mass. 

The Prilongia-Castello thrust-plane describes a wider torsion-are 
round the south-west than the higher thrust-plane above the 
Richthofen Reef, but it is characterized by the same A & B spiral 
movements which are found to answer generally for the southern 
torsion-ares in this neighbourhood. ‘he Castello portion represents 
the B-spiral, where the underlay has been tilted with a steep inward 
dip and twisted northward and north-westward, while the overlay 
has been twisted almost horizontally outward to south and south- 
east. The Prilongia portion represents the A-spiral, where the 
underlay has been steeply tilted with a north-easterly dip and twisted 
in that direction, while the overlay has been twisted south-westward. 
The overlay of the Priilongia overthrust comprises the strata of the 
Pralongia ridge, which on the other side of the ridge form the 
underlay of the peripheral overthrust of Sett Sass. Therefore the 
strata of the Pralongia thrust-whorl have endured twining strains 
of the same nature as those described on a preceding page for the 
main whorl of the Sella Massive. 

The normal fault of Monte Sief.—The flexure of the 
Monte-Sief strata towards the north is very marked. The Wengen 
rocks strike north 40° east, and dip 35° north-westward. The flexure 
is cut by a highly-inclined normal fault, with downthrow towards 
Sett Sass. As the angle of inclination is much greater than the 
inclination of the reversed fault-planes of Montagna della Corte and 
the Richthofen Reef, the three fault-planes would meet if continued 
upward. Thus the tendency of compression was to bring the over- 
thrust mass of Sett Sass always closer to the Middle Triassic 
anticline of Monte Sief and Col di Lana. 

Once more it is the softer Wengen-Cassian Series which has been 
chiefly crumpled, sliced, and torn, together with small shear-frag- 
ments of the overlying calcareous rock, between the advancing 
overthrust mass of Upper Trias and the upwardly-bulged mass of 
Middle Triassic limestone (see fig. 10, p. 586). 

The normal fault of Sett Sass.—The Schlern-Dolomite 
rock of Sett Sass, which has a scarcely perceptible dip (about 8° to 
10°) above the Richthofen Reef, makes a steep flexure on the north 
side of the mountain, cut by a slight flexure-fault. The Raibl and 


Vol. 55.] TORSION-STRUCTURE OF THE DOLOMITES. 621 


Dachstein strata lie in the hollow of this flexure at the Eisenofen 
huts. Immediately north of the huts and of Lake Valparola, Cassian 
strata are dislocated by a steep fault and brought, along with Schlern 
Dolomite, into complex stratigraphical relations with the Raibl strata 
and Dachstein rock in the Sett-Sass basin. 

This Eisenofen-Valparola Fault with southerly downthrow was 
previously demonstrated by the writer to be a curved continuation 
of the east-and-west Falzarego Fault which runs from the Tra-i-Sassi 
Pass to the Ampezzo Valley. In its portion north of Sett Sass this 
fault may be regarded as a reversed one limiting the northern 
side of the basin, and neutralizing the steep flexure-fault of Monte 
Sief which limits the Sett-Sass basin on the south. The Monte- 
Sief and Sett-Sass Faults give expression to a general overcasting of 
earlier east-and-west anticlines towards the south during the later 
torsion-movements. At the same time we have seen how com- 
pensating overcasts took place towards the north in the Langs-da-Fiir 
Anticline north of Siadu. 

The northern fold-are of Prailongia and Sett Sass.— 
A northern fold-are is presented in the curved form of the Langs- 
da-Fiir Anticline, but the anticline is cut off from the basin of 
Siadu by the intrusion of porphyrite continuous with that of the 
Pescosta centre (p. 583). ‘The Siadu basin is cut off from a corre- 
sponding basin on the opposite side of the Sore stream by the 
diagonal arch of Prilongia continued northward between Ru and 
the Centurinus Dolomite-group. The downthrow from this arch 
towards the Centurinus group is part of the long downthrow from 
the north-north-west and south-south-east fault-shears between 
Abtey and the Dolomite-group of Kreuz Kofl and La Varella. 

Cross-arches.—the anticlines of the earlier epoch of com- 
pression are the easterly continuation of the arches demonstrated in 
the Sella area, and will now be briefly mentioned in the same order, 
to facilitate comparison (p. 609) :— 

1 (a) Langs-da-Fir limiting anticline; (6) Siadu trough. 

2(a) Ruones-Piccol-Tra-i-Sassi arch ; (0) Stuores and Sett-Sass trough 
(Fondo di Valparola). 

3 (a) and (6) [wanting]. ' 

4(a) Southern arch of Pralongia and Sett Sass; (6) southern trough 


(underlay of southern overthrusts). 
5 (a) Monte-Sief and Col-di-Lana limiting anticline. 


The diagonal series of cross-buckles, and the torsion-curves and 
torsion-radii associated with them, indicate two later diagonal 
arches across the middle of the area—the Pralongia-Soraruaz arch 
and the Hisenofen-Sett Sass arch (2434 metres). 

The main diagonal anticline is that of Campolungo, limiting the 
area on the west, and the eastern limit is the diagonal arch crossing 
Tra i Sassi, and forming a natural boundary between the two 
distinct torsion-systems of Enneberg and Ampezzo. 

If we consider now the position of the strata in the Sett-Sass 
area previous to the torsion-movements, clearly the Cassian strata 
occupied a relatively high position in the arches north and south of 


622 MISS M. M, OGILVIE [MRS. GORDON] ON THE _[ Aug. 1899, 


that area, while the Upper Triassic limestones were well depressed 
in the Sett-Sass trough. It was therefore natural that, during 
oblique compression and overcasting in the later period of folding, 
reversed faults should carry to a certain extent lower horizons in 
the arches above higher horizons in the troughs. 

Compensating torsion-movements in companion 
basins.—The chief diagonal anticline is that of the Campolungo 
Pass, and the predominating torsion-phenomena have distinct 
reference to the torsion-buckles formed at its superposition upon 
the Gréden-Pass and Buchenstein Anticlines. 

The leading torsion-curves of Sella are determined by the oblique 
and divergent faults which pass south-eastward from the Gréden 
Pass to the Campolungo arch, and by the oblique faults which pass 
north-eastward, trom the Cima-di-Rossi and Col-di-Luc portions of 
the southern anticline, towards the Campolungo arch. 

The leading torsion-curves of Pralongia and Sett Sass are deter- 
mined by the oblique faults which pass south-westward from the 
Langs-da-Fur Anticline to the Campolungo arch, and by the north- 
western faults which pass from the Buchenstein Valley to the 
Campolungo arch. Both the basins east and west of the arch are 
elliptical, but the long axis of the Sella basin is directed north- 
north-east and south-south-west; while the long axis of the 
Prilongia and Sett-Sass basin is directed north-north-west and 
south-south-east, parallel with the leading torsion-curves (Corvara- 
Contrin, Ruones-Castello, Piccol-Lake Valparola). 

Whereas the torsion of the strike in the anticlines has only 
been through a small angle of about 20°, here, as at Sella, the strike- 
torsion is greater in the higher horizons occupying the syncline, 
where it is north-east and south-west and north-north-east to south- 
south-west, in the immediate neighbourhood of the diagonal arches 
west of Sett Sass, veering to north-west and south-east in the 


Castello meadow. 


Conclusions. 


(1) The area of Sett Sass and Pralongia originally formed part of a main 
east-and-west syncline situated between a Groden-Hnneberg anticline on the 
north and a Belvedere-Buchenstein anticline on the south, and dating from an 
early period of crust-movement so far begun in Middle Triassic time (see ‘ Coral 
in the Dolomites, Geol. Mag. 1894). ' 

(2) During the great Middle Tertiary epoch of crust-compression this syncline 
was thrown into a series of cross-arches and troughs oblique to the former 
synclinal axis; the chief diagonal arch was that of the Campolungo Pass, which 
subdivided the original syncline into two adjacent basins, Sella on the west and 
Pralongia and Sett Sass on the east, and whose superposition on the Groden- 
Pass Anticline has been accompanied by igneous intrusions. 

(3) During the continuance of crust-compression neutralizing flexure and 
overthrust-faults took place in the combined sense of the earlier and the later 
movements ; thus torsion fault-curves were formed and were associated with 
fault-radii across the curves. The fault-curves of Pralongia and Sett Sass 
describe an are round the south-west, while the fault-radii diverge from a 
northern area of convergence towards westerly, west-south-westerly, south- 
westerly, south-south-westerly, and southerly directions. 


Vol. 55.] TORSION-STRUCIURE OF THE DOLOMITES. 623 


(4) A series of four crust-whorls was determined by the inclined planes of 
the fault-curves. The lowest whorl is exposed in Middle Trias, and partly in 
Lower Trias; it passes through Langs-da-Fiir, Campolungo, Cherz, Monte Sief, 
to Castello, and is characterized by inclined faults towards the Pralongia and 
Sett Sass basin, and intrusive porphyrite in the faults. The succeeding whorl 
is exposed in the Wengen-Cassian Series and passes through the Ruones, Pra- 
longia, Montagna della Corte, and Castello meadows. It is characterized by 
overthrust southward, and steep flexure northward towards Stuores and the 
southern curve of Sett Sass. The next whorl is fragmentary, being represented 
by the Cassian and Schlern-Dolomite rocks composing the Richthofen Reef and 
the continuation of that slice round the western and southern curvature of Sett 
Sass. This fragment also shows overthrust southward and steep northward 
flexure. The highest whorl in this basin is that of the Upper Trias composing 
Sett Sass, which has been overthrust southward above the Richthofen Reef and 
bent steeply northward towards Eisenofen. All four whorls are incomplete on 
the east side of the basin, where they are cut by cross-faults. 

(5) The most important tectonic feature is the result of the particular com- 
bination of normal and reversed faults similarly inclined, but with very different 
angles of inclination. The most compressed portion of the area is at Monte 
Sief and Sett Sass, where the series of faults is as follows :— 


Pl meet { 2 Highly inclined normal fault at Monte Sief. 
Say Ml 6. Moderately ,, reversed ,, at Montagna della Corte. 


upward. | Slightly ., . |. ab ble IRichthofen Bele 
Planes meet fd. Moderately ,, normal ,, in Sett Sass. 
downward. | e. Highly » reversed ,, at Hisenofen. 


The grouping of these inclined faults is such that increased compression 
tended to bring the mass of strata composing Sett Sass nearer the strata of 
Monte Sief and Col di Lana. 


Appendix. 


Analogy of Monte Sief with Rodella Hill.—The diagonal 
fault between Sasso di Stria and Sett Sass has effected a lateral 
southward displacement of the strata which composed the east-and- 
west anticline of Cima di Rossi, Belvedere, and Col di Lana. The 
eastward continuation of this anticlinal buckle of older Trias and 
lava must be sought some distance south of the Nuvolau and 
Carnera Dolomite-massives. 

The diagonal fault west of the Sasso di Stria arch is parallel 
with the diagonal fault of the Sella arch, and these two faults form 
the eastern and western limits respectively of the area of torsion 
described in the foregoing pages. These are definite confines, 
which limit a four-sided area, influenced by the Gréden-Pass torsion- 
system on the north and the Buchenstein torsion-system on the 
south. The area is a typical torsion-unit in the Dolomites, and 
displays in a marked degree the phenomena of interference cross- 
fauits, cutting a series of peripheral overthrusts round the synclines, 
and parallel flexure-faults between the anticlinal buckles and the 
synclinal basins. 

Both the limiting diagonal faults displace the outcrop of the 
Belvedere-Buchenstein Anticline towards the south: that is, they 
effect downthrow on their east side. MRodella is present, west of 
the Sella Fault, as a curious torsion-block of older rock in the imme- 
diate vicinity of the torsion-basin occupied by the Platt-Kofl and 


624 MISS M. M. OGILVIE [MRS.GORDON|oN THE [ Aug. 1899, 


Lang-Kofl group. Similarly, Monte Sief is left west of the Sasso- 
di-Stria faults, as a torsion-block of older strata in close proximity 
to the Sett-Sass basin. 

Lake Alleghe.—Lake Alleghe seems to be an area of con- 
vergence for several diagonal faults. The north-north-westerly and 
south-south-easterly fault from Corvara to Contrin continues down 
the Cordevole Valley towards Caprile and Lake Alleghe. The faults 
on both sides of the diagonal arch of Sasso di Stria, as well as a 
diagonal fault west of the next diagonal arch of Travernenzes and. 
Nuvolau, all tend to converge if continued southward towards Lake 
Alleghe. Hence the lake seems to be a chief centre of torsion- 
radii in the district (see fig. 22, p. 630). 

The Cortina area.—lI should wish here to indicate briefly how 
the laws of torsion may be also applied to the stratigraphy of two 
other localities which I examined and mapped geologically.! 

The Falzarego Valley represents an older east-and-west anticline 
which has been twisted round the southern arc of the Tofana group. 
The fault-curves hade northward and pass obliquely north-westward 
through Tra 1 Sassi and north- eastward round the Cortina meadows. 
The chief diagonal arch which has crossed the anticline is that of 
the Ampezzo Valley. A sharp curvature of the strike from the 
Falzarego to the Ampezzo Valley is again the seat of intersection of 
normal and reversed faults by a group of radiating faults. These 
faults radiate southward and eastward from the Tofana massive 
at Verviers, Lake Majorera, and Romerlo. The Tofana bundle of 
fault-radii is therefore, in its south-easterly direction, compensatory 
to the Centurinus bundle north of Pralongia, where the fault-radii 
are directed towards the west and south-west. 

Dirrenstein Mountain.—The present author’s map of 
Dirrenstein Mountain’ exhibits a complicated system of faults. 
The leading fault-curves describe a narrow northern fold-are round 
the mountain, and hade southward. 

The Diirrenstein Massive denotes cross-buckling superposed upon 
an older east-and-west trough. The east-and-west anticline on the 
north has been penetrated by a series of reversed faults, slicing chiefly 
Muschelkalk and Wengen strata. A steep northward flexure at the 
Sarl Kofele has been cut by a normal fault letting down the Cassian 
and Schlern-Dolomite strata of Dtrrenstein. The latter are cut 
into several cheaigfices in the part next Sarl Kofele, so that the 
section from the anticlinal arch to the synclinal basin would closely 
resemble that of the equally compressed area of Col di Lana, Monte 
Sief, and Sett Sass. The central portion of the Diirrenstein Massive 
represents part of the original trough, round which older strata 
have been twined ; the inthrow is on Platz meadow. ‘The general 
strike is north-west to south-east, in the central part of the area, 
but in the torsion-ares north of it the strike veers round from 
north-east and south-west to north-west and south-east. 

Two features deserve special attention in this area: one is that 


1 Quart. Journ. Geol. Soc. vol. xlix (1893) map B, pp. 28-32 & pp. 68-69. 
2 Ibid. map C, facing p. 32. 


Woks 51 TORSION-STRUCTIURE OF THE DOLOMITES. 625 


overthrusts have taken place towards the north; the other is the 
torsion of the strike in a north-westerly and south-easterly direc- 
tion. 

With regard to the northward overthrusts, the Dirrenstein 
area resembles the Gréden-Valley and Seis-Alp area farther west. 
Both areas are proximal to the schists of the Central Alps. The 
inclined faults therefore hade away from the main anticline of the 
Alps, so far as it is represented by the flanking schists. This is 
quite in accord with my experience within the Dolomites—the 
inclined planes hade away from torsion-buckles and 
towards the chief synclinal basins within the areas 
specially examined. 

With regard to the south-easterly torsion of the strike at 
Diirrenstein, it corresponds with the general torsion which the 
district of the Dolomites undergoes in the neighbour- 
hoodof the Sexten Valley. It is explained as a strike 
compensatory to, and co-ordinated with, the crust-torsion in the 
direction of the north-north-western and south-south-eastern arches 
of the Gréden and Enneberg area. 


VI. ApprLicATION oF THE PRINCIPLES OF ToRSION IN THE DOLOMITES 
AND IN THE JUDICARIAN-AsTA REGION, 


Correlation of anticlines and synclines.—So far as 
the observations of the present author go, there is one general law 
which governs the inclination of the fault-planes in the torsion- 
structure of the Dolomites. Whether overthrust-planes or normal 
fault-planes, if they are parallel with the strike of the rocks, 
they incline towards the areas of subsidence in the particular 
localities. 

Hence at Diirrenstein and the Prags margin the inclination of 
the fault-planes is south and south-west towards the broad synclinal 
area of Dachstein Dolomite, comprising the Rothwand, Pfanes, 
Tofana, and Cristallo groups. Round the southern curve of the 
same synclinal area, my observations in the Falzarego and Cortina 
district showed that the fault-planes incline northward and north- 
westward. . 

Again, it has been found in Enneberg that thef&ehief anticlines 
have distinct reference to the particular synclines 
north of them. The knee-bend flexures facing south are the 
most strongly compressed. Overthrust-fractures have occurred, 
while torsion has, at the same time, produced a fan of obliquely- 
set anticlinal slices at varying angles of obliquity to the original 
anticlinal axis. Corresponding phenomena have taken place where 
return knee-bends formed facing the north, and were twisted in the 
diagonally opposite direction. The squeezed and shattered anti- 
clines are pierced by intrusive rocks, for the most part injected along 
fault-planes. 

The Gréden-Pass Anticline has the Spitz-Kofl and Sass-Songe 


Gs. Gis. No. 219: 28 


626 MISS M. M. OGILVIE [MRS. GORDON] on THE  [Aug. 1899, 


mountain-group as the corresponding syucline of the northern wing, 
and this syncline is marked by attenuation of the strata towards 
the Puez Alp, where Jurassic and Cretaceous rocks are present. 
The anticline of the Buchenstein Valley has on the south and south- 
east Sella and Sett Sass, as the corresponding syncline of the 
northern wing. Boththese synclines are characterized by a similar 
attenuation of the rocks towards an inner depression, containing 
inthrown high horizons of Upper Triassic or even Jurassic rock. 

The relations would be extremely simple, had they not been 
complicated by the diagonal torsion-folds. The diagonal anticline 
of Enneberg is that which forms the Abtey Valley, and is recog- 
nized again in the Corvara, Ruones, Campolungo, and Cherz-Hill 
buckle crossing from the Grdden-Pass Anticline to that of the 
Buchenstein Valley (see map, Pl. XL). 

It is the combination of longitudinal and diagonal 
buckling which has marked out the separate synclinal 
areas in Knneberg; and this combination has been 
explained fully as the result of the curving torsion 
fold-ares formed in diagonally opposite senses. 
Those of any one torsion-system combine with those 
of adjacent torsion-systems to produce a whorl- 
shaped arrangement of anticlines round separate 
synclinal areas. 

Anticlines have been twisted round synclines, and the rocks in 
the synclines have themselves been twisted and distorted, buckled 
up and depressed, overthrust and faulted normally, cross-faulted 
and cleaved, to an extent that has not hitherto been realized. 

Tiers-Duron torsion-system.—We may apply the prin- 
ciples of torsion throughout the Dolomites. And, first, to recur 
to the continuous east-and-west ridge from Mahlknecht to Col 
di Lana, which I replaced in imagination above (p. 562). The 
ridge as there reconstituted was supposed to have been once an 
actual line of Middle Triassic flexure and lava-outflow, limiting an 
ancient submarine terrace to the north of a wide sea-basin. The 
same line may be traced westward through Botzen and eastward 
towards Pieve di Cadore, Tolmezzo, Raibl, etc. (see fig. 22, p. 630). 

The continuity of the ridge was described as having been broken 
in the Tertiary period of Alpine upheaval by the influence of the 
torsion-forces demonstrated in the case of the Buchenstein part of 
the ridge (§ III, pp. 587-590). 

In the area immediately west of the Buchenstein Anticline I 
would distinguish a torsion-system extending through the broken 
anticlines of the Tiers and Duron Valleys, with the Schlern and 
Platt Kofl Mountains as northern synclines, and Rosengarten as 
the southern syncline. The cross-buckle of Mahlknecht separates 
the adjacent synclines of Schlern and Platt Kofl, much as the Cam- 
polungo buckle separates the adjacent synclines of Sella and Sett 
Sass. The anticlinal axis of the Tiers-Duron system is set west- 
south-west and east-north-east. The Rodella portion has been 
twisted northward, and the Tiers portion southward. 


Mol sey TORSION-STRUCIURE OF THE DOLOMITES. 627 


The opposite Dolomite-mountains represent torsion-segments 
curving away one from the other and from the torsion-axis along 
the various correlated oblique directions, as already demonstrated in 
the cases of Sella and Sett Sass. These examples of oblique torsion- 
systems along one and the same original line of strike suffice to 
prove the general application of torsion to the complicated strati- 
graphy of the neighbourhood. The complications would not have 
arisen, had not Permian and Middle Triassic flexures previously 
existed in another direction of strike than that called forth by 
the horizontal forces acting during the later uprise of the Alps. 

On the other hand, all the faults are reduced to order, when it is 
recognized that the area has been broken up into a number of 
individual torsion-systems in each of which the strike has under- 
gone the necessary change. Adjacent systems are separated by 
cross-faults, many of which give evidence of having continued 
to act as planes of adjustment after torsion had taken place (see 
also p. 574). | 

Strike-torsion at Fassa.—In order to investigate further 
the action of the later horizontal forces of compression and torsion, 
one of the torsion-axes of strike must be followed. The new strike- 
axis of Col di Lana and Cima di Rossi, which lie east-north-east 
and west-south-west across the Buchenstein Valley, curves south- 
west at Canazeiand passes obliquely across the Fassa Valley. There 
it forms the torsion-axis of a system in which the southern spurs 
of Rosengarten branch at the north-western area of subsidence, 
and the diagonally opposite, south-eastern area is occupied by the 
Vallaccia and Monzoni group (fig. 22, p. 630). ‘The Buchenstein and 
the Fassa axes form together one torsion-curve veering from west- 
south-west to south-west. A parallel axis of torsion farther south 
passes through the ‘ eruptive’ area of Fleims and Predazzo. The 
torsion-axis may be said to lie in the eruptive rocks, while areas of 
subsidence are present all round the eruptive centre except on the 
south-east side. The Latemar group occupies the area of subsidence 
on the north-west side of the Fleims axis, and the dolomite-rocks 
of Viezzena and Dosso Capello lie south of the axis. The torsion- 
curve in both these cases is a curve which is characteristic of the 
Judicarian-Asta system of faults (pp. 577 & 602, footnotes). 

The angle of torsion through which the old east-and-west strike 
was shifted was much greater at Fassa and Fleims than at Buchen- 
stein ; and the eruptive group of Viezzena and Predazzo occurs where 
the torsion-curve crosses the original strike at an angle of about 45°, 
that is, where the torsion was unusually pronounced. At the same 
time, the area is proximal to the Permian porphyry. The inevitable 
conclusion is that eruptive activity broke out in that area afresh as 
a result of torsion, and must therefore have occurred at a 
fairly advanced stage of the torsion. The latest outbreaks in 
the area may be identified with the most acute phase of torsion, since 
the transverse, as well as the diagonal, faults which cut the main 
overthrusts and torsion strike-faults of the Gréden-Pass and the 
Buchenstein-Valley systems are occupied by fault-dykes, radially 

28 2 


628 MISS M. M, OGILVIE [MRS.GoRDON| on THE [Aug. 1899, 


arranged with regard to the Viezzena and Predazzo area. They 
pass from it in a south-south-westerly and north-north-easterly 
direction to Buchenstein, more north-and-south at Rodella and the 
Sella Pass, and more south-south-east and north-north-west towards 
Rosengarten, the varying direction agreeing with the reciprocating 
character of torsion-faults. 

This arrangement shows the radiating faults to have 
been initiated in association with eruptive outbreaks 
in the area next the resisting mass of Permian eruptive rock. 
Also, they clearly mark a relatively late phase in the torsion, since 
they frequently cut less curved faults belonging to the Asta system, 
although in other cases they pass into them and form a Judicarian- 
Asta curve (see footnote, p. 577). Such a curve, however, is no 
simple tectonic line, but the result of cross-folding. 

Torsional eruptivity.—Upon the basis of the observations 
detailed above, we have to distinguish different phases in the pro- 
tracted history of torsion, marked by progressive phases in the 
collateral history of eruptivity. 

The ‘middle limb’ between the anticlines and synclines of the 
earlier east-and-west Alps presented a series of septal lines of crust- 
weakness, to which were added in the Judicarian district north-and- 
south lines of crust-weakness attendant upon the earlier Permian 
intrusive mass. These were the special lines which determined 
the form of the later peri-Adriatic depression. 

The histcry of torsion starts with oblique fracture of the old 
septal lines along correlated diagonal lines (see p. 571). Escape 
of the underlying molten rock along the old fold-septa, inrush 
towards and spreading out of the underlying rock within the 
torsion-buckles, which took shape as torsion proceeded, and injection 
of dyke-material into torsion-faults in course of formation may 
be regarded as progressive stages of torsional eruptivity during 
mountain-upheaval. Hruptivity is a necessary part of the regional 
dynamic phenomena (see p. 611). The later phases of decadence 
have reference more especially to the synclinal torsion-basins. The 
demarcation of a torsion-basin, the heaping-up of the strata 
peripherally, and their attenuation centrally are results of 
torsion-movement. And the local escape of underlying rock at the 
rim or within attenuated central areas denotes a further stage of 
torsion. 

Thus torsional eruptive activity may be said to have marked 
time in a history of Alpine movement, which extends from the later 
Cretaceous to the present age. 

Characteristic stratigraphical features in the Judi- 
carian-Asta district.—The geology of the Adige Basin and 
the Cima d’Asta area has been made known in a series of able 
works by Suess, Lepsius, Vacek, Bittner, and other well-known 
Austrian geologists. A brilliant chapter by Suess, in his ‘ Antlitz 
der Erde,’ summarizes the facts as known in 1885, and leads the 
reader clearly and carefully through the intricacies of the Adriatic 
Subsidence. Cima d’Asta was described by Suess as a Horst, 
since the investigations of Mojsisovics had pointed out the repeated 


a 


Vol. 55. | TORSION-STRUCIURE OF THE DOLOMITES. 629 


appearance in the Dolomites of northwardly-inclined normal flexures 
passing into faults with downthrow on the north; whereas Suess, 
Bittner, and other geologists had traced overfolds and thrusts 
towards the south and south-east in the area south of Cima d’Asta, 
and in the Judicarian district. 

The present author and Dr. Salomon (see p. 565) showed the 
existence of overfolds and overthrusts within the Dolomites whose 
direction agreed with that demonstrated in the Judicarian and Asta 
areas. Now this paper shows that a characteristic feature of the 
Dolomites is the repeated combination of flexures and 
flexure-faults, towards the north and north-west, in 
the sense demonstrated by Mojsisovics, with overfolds 
and overthrust-faults towards the south and south- 
east: that is, in the Judicarian-Asta sense. The inclina- 
tion of the planes is in both cases precisely the same, but the actual 
combined result is so far neutral. 

The neutralizing action of similarly-inclined normal 
and reversed faults whose direction is curved, explains 
the recurrence of Dolomite-massives with the same strata and the 
same tectonic features over a wide area. 

A further fact brought out in this paper is equally significant 
for the structure of the Dolomites, namely, the relation of return- 
folds and overthrusting to the original fold-system. The strike- 
faults on the southern and inner portion of the Dolomites mostly 
produce overthrust southward ; the strike-faults along the northern 
rim (as, for example, Diirrenstein) are overthrust northward. 

This want of uniformity is paralleled by the researches of 
Bittner and Vacek in the Adige Basin. There the chief fault is the 
Judicarian Fault, ranging north-north-east and south-south-west, 
and with it the occurrences of eruptive rock are associated. Along 
this western limit and throughout the mountains, the overcasting 
and overthrusting are eastward ; whereas along the eastern limit of 
the same area the quartz-porphyry has been overthrust westward 
over the rocks of the Adige Basin. The occurrence of fold and 
back-fold, the frequent obliquity in the shape of folds, the variation 
of the same lines of disturbance from gentle flexures into sharp 
faults, and the relations between strike and diagonal faults are 
identical. 

The Judicarian Faults, north-north-east and south-south-west, 
are said to be crossed by Asta Faults, which come from the Lom- 
bardy Plain, both in an east-south-easterly and east-north-easterly 
direction, or are likewise associated with dykes. Certain sharp 
north-and-south faults, sometimes more north-north-west and south- 
south-east, cut the others. The virgation of faults is still another 
feature common to the Dolomites and to the Judicarian-Asta region ; 
while the latter area also confirms the observation, made with 
respect to the eruptive rocks in Fassa, Fleims Valley, Buchenstein, 
and Hnneberg, that the bosses and dykes are present 
pre-eminently in twisted anticlines and along diagonal 
lines of fault where torsion has been greatest (fig. 22, 
p- 630). 


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Mol gs. THE TORSION-STRUCTURE OF THE DOLOMITES. 631 


The identity in the tectonic character of the adjacent neighbour- 
hoods is unmistakable ; and if torsion can be applied correctly as 
an explanation of these features in Enneberg, there is every reason 
to suppose that it can be applied for the whole area. 

Age of acute torsion.—The Judicarian or north-north-east 
and south-south-west system of folds and faults in the adjacent 
neighbourhood affects the whole series of rocks, from Permian to 
Middle Tertiary. Hence the oldest period which can be adduced for 
the acute stage of torsion and the injection of the eruptive rocks 
along the chief torsion fault-lines and curves is Middle Tertiary. 

In a word, the outbreak of the more acid series of 
eruptive rocks in Southern Tyrol marked an advanced 
phase in the phenomena of strike-torsion in that 
region, and was associated with an important system of 
diagonal and transverse faults, some of which in all 
probability still act as planes of lateral displacement 
and crust-adjustment. 

It is worthy. of remark, that the recurrences of eruptive activity in 
Southern Tyrol would thus be proved to have been always associated 
with great crust-movements: (1) those of Permian uprise and 
mountain-making ; (2) those of Triassic depression; (3) those 
of Tertiary torsion and mountain-making, inducing and followed 
by local subsidences. 

During the period of torsional uprise, the eruptive activity 
chiefly took the form of central bosses and laccolithic expansions 
in the characteristic crust-buckles, and was accompanied by fault- 
dykes and sills. During the subsequent period of local depression 
the activity has largely taken the form of superficial flows and 
volcanic outbursts. 

It is just possible that some of the interrupted north-and-south 
lines of fault in the Judicarian-Asta region (fig. 22, p. 630), as well as 
the north-and-south exposures of Permian eruptive rocks, in which 
again Tertiary rocks burst through, may correspond in position to 
ancient transverse lines and valleys in the pre-Permian and Permian 
Alps. This seems especially worthy of attention in the occurrence 
of the Tertiary rocks in the Vicentine area, Asta, and Fleims-Fassa 
centres. These areas occur along a north-and-south line, and in 
each case the eruptions are associated with outcrops of old schist- 
rocks or of older eruptive rocks. In Scotland, it has been proved 
that fresh outbreaks of eruptive rocks in many cases followed old 
valleys.’ 

Peri-Adriatic torsion-curves.—The sketch-map of the 
Judicarian-Asta area given by Suess* has been taken by the 
present author as the basis of a new diagram (fig. 22). Torsion- 
curves have been drawn through the area in accordance with the 
principles laid down in the present paper. Generally considered, it 
depicts a region folded in one geological age along east-and-west 


1 A. Geikie, ‘ Anc. Vole. Gr. Brit.’ vol. ii (1897) pp. 61, 65, 96. 
2 « Antlitz der Erde, vol. i (1885) p. 322. 


632 MISS M. M. OGILVIE [MRS. GORDON] on THE [ Aug. 1899, 


lines, and in a much later geological age folded obliquely to the old 
lines—cross-folding and crust-contraction haying followed longi- 
tudinal folding and contraction. 

The Judicarian strike in the western area is north-north-east and 
south-south-west, parallel with the strike of the new folds at Sella ; 
and the development of this series has been accompanied by the 
development of a correlated series in a north-north-westerly and 
south-south-easterly direction (see p. 612), shown in the Trieste 
strike. Torsion of old anticlines has taken place in these directions, 
with the development of northern and southern fold-arcs round 
individual basins. The curve from Schlern to the Sexten Valley 
describes a northern torsion-are round the basin of the Dolomites, 
while the curve from Cima d’Asta to Pieve di Cadore and Auronzo 
describes a southern torsion-are round the Dolomites. 

The leading curves of the torsion-system trend from west to 
south-west and south-south-west in the Adige and Judicarian area, 
and from east to south-east and south-south-east in the Carinthian 
and Trieste area. The large sheet of Permian porphyry presents a 
disturbing element in the course of the torsion-curves, dividing the 
Adige torsion-basin from the basin of the Dolomites and deflecting 
the curves round its southern edge. 

The diagram shows at a glance an important general correlation. 
Short lines in an east-and-west direction have been drawn by the 
writer to indicate the existence of an older strike, as inferred above 
and in a former paper. These east-and-west lines are crossed by 
the torsion-curves at increasingly oblique angles where the curves 
trend south-westward and south-south-westward, and it is there 
where Tertiary eruptive activity. has been displayed in the Judi- 
carian reglion—a region of earlier Permian eruptivity. 

The relation of the peri-Adriatic system of torsion-curves to the 
torsion-phenomena of the Alps generally cannot be discussed here. 
In my opinion, the principles of crust-torsion exemplified in the 
region of the Dolomites can be shown to be equally applicable to 
the structure of the entire Alpine system. ‘This I propose to deal 
with elsewhere. 


I cannot conclude without giving expression to a deep feeling of 
personal indebtedness to the writings of Prof. Suess and Dr. Bittner. 
The classical works in which the former has traced the great curves 
of the Alps and its related mountain-systems, taken together with 
the persistent demonstration by Dr. Bittner of the characteristics 
of the complicated fault-system in various regions of the Kastern 
Alps, lead almost inevitably to the conception of crust-torsion on 
a grand scale. 

I must again gratefully acknowledge my great indebtedness to 
Baron F. von Richthofen, whose original interpretation of the 
Triassic succession in the Dolomite country has not only formed 
the foundation for the researches made by me and all other workers 
in the same field, but stands to-day undisturbed after forty years 
of controversy. 


Hi 
het al 
pas int 


Quart. Journ. Geol. Soc. Vol. LV, Pl. XL. 


GENERAL GEOLOGICAL 
of the 


SELLA MASSIVE ano ENte= 


By ; 

Maria M.Ogilvie, D.Sc (Mrs 
1898. 

Scale of metres. 


© 100260 0; 
wih SRE sn , 1000 2000 2500 3000 


Leuine Wothensiein. 
—_ ———s 


Vol. 55.] - | TORSION-STRUCTURE OF THE DOLOMITES. 633 


My grateful thanks are especially due to Prof. Lapworth, who, 
with his unfailing kindness to workers in geology, has freely ex- 
tended to me advice and encouragement. The reader will have 
gathered for himself to what extent the general inferences drawn by 
Prof. Lapworth accord with my own detailed field-work ; and it was 
a matter of especial gratification to me when he consented to read 
this paper on my behalf at the present meeting of the Geological 
Society. 

Finally, my cordial thanks are also due to Prof. Watts for his 
kindness in communicating this paper, as well as for his careful 
microscopic examination of the specimens of igneous rock brought 
by me from various localities in Enneberg. 


EXPLANATION OF PLATE XL. 


General Geological Map of the Sella Massive and Enneberg, on the scale of 
500" or about 1°267 inches to the mile. 

It will be noted that a small area north-east of Vallon, left white in error, 
should have been shaded as Schlern Dolomite. 


Discussion. 


Prof. Bonney said that he had not visited the region since 1880, 
and then had not passed over the precise area examined. The 
hypothesis advanced by the Author explained many difficulties, but 
he had doubts about the date assigned to the eruptions, for he felt 
convinced that these were of Triassic age. Also he much doubted 
the ages assigned to the movements, namely, whether the east- 
and-west foldings were the earlier. He had pointed out more than 
ten years ago that in the Alps, most strongly in the eastern 
and western portions, foldings could be traced from north-north- 
east to south-south-west modifying the east-and-west foldings, 
which, however, had an even boundary on thenorth. The former 
foldings agree with post-Carboniferous and pre-Mesozoic folds, of 
which he gave instances. The Alps, in fact, were regions of 
repeated movements, and greatly as he was impressed by the ability 
of the paper, he must suspend his judgment till he could read and 
consider it thoroughly. ; 

Prof. Sottas expressed his admiration of this brilliant and solid 
piece of work, which had been rendered intelligible to the meanest 
capacity by the lucid explanation of Prof. Lapworth. In the 
course of the exposition we had witnessed with mingled feelings 
the dissolution of Richthofen’s coral-reefs, as they disappeared in a 
chaos of thrusts and overfolds, and the evolution of a new system 
which was more wonderful than the old. The structure of the 
Dolomites still seemed to the speaker suggestive of coral-reefs, which 
could not have been mere fringes, but were comparable to barriers 
and atolls; and it was possible that in the Tyrol we were confronted 
with mixed phenomena. If so, the disturbances of the district could 
not be regarded as affecting a homogeneous system of sheets, and 


Quart. Journ. Geol. Soc. Vol. LV, Pl. XL. 


Genera GeotocicAL Map 
of the 


SELLA MASSIVE ann ENNEBERG 


Varella. 


Centuries Spitz. 


Maria M. Ogilvie, D.Sc (M's Gordon) * 5064. 
1898. 
Scale of metres. 
© Wo0zt0H0K00%0 | | |, 1000 1500 2000 2500 3000 3500 4000 4500 5000 métres. 
Luine Wotkenstein. 


CRESPEINA DE DoRA. 


aren, gall. By Zz at 
SIMANi. Wo 


—— 


! \Colfosco 
PLescost 


SOPOT Eb, 


é [i idnendogln 


ONDO DI. VALPAROLA: 


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‘ = ae ie See 6 = : Ssaees 
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f poe: ee EDachsteinhalle.. | Se Piéve: 
#} te LIOR race rencosrsied ; COE 
Zt 7 : 
ad ve a > 6 Schlern Dolomitesttt: eitins PER M PAIN crsssssssssesee FAULT LINES. Probable continuation of do. 
5 Canazet. * Cine Rosst: i hee ee a. FCASSIAM .orrssreve —— STRIKE ano DIP ati 
HYG. + 2392) = : | Eruprive Rocks. Conracr Rocks. acaba OPER CR SLIPS. “SSRs: g 


78 , r é ‘ y 5 tint 
RS RN eR em = i A A ea A gR geenn—y nga l  eatepeter mn-i. 


634 THE TORSION-STRUCTURE OF THE DOLOMITES. | Aug. 1899, 


account should be taken of the original inequalities of the sea-floor, 
which might find a parallel in the tropical Pacific. The tuffs of the © 
district could not all belong to the Tertiary era; on this point the 
evidence of contemporaneous Triassic corals seemed conclusive. 

Prof. Warts pointed out that, among the rocks submitted to him, 
there were some undoubted tuffs, some augite-porphyrites and 
labradorite-porphyrites, the constituents of which occurred in the 
tuffs, and one example of a rock which appears to be related to 
hebenerite-porphyrites. 

Dr. J. W. Gregory expressed his congratulations to the Author 
on the brilliant results attained by the combined application of 
stratigraphy and paleontology. He doubted whether the coral-reef 
theory would have been proposed had any detailed study of the 
corals been then made. The resemblances between the dolomites in 
the Eastern and Western Alps was of much interest: in the latter 
area the principal Triassic dolomite-mass was similarly isolated by 
faults and intersected by thrust-planes, and the reef-corals described 
from it were of Upper Mesozoic age and had been let down into the 
dolomites by trough-faults. With reference to the age of the volcanic 
rocks, it had been proved in the Cottians that they belonged to more 
than one age. Along the great bow of the Western Alps there were 
outcrops of massive igneous rocks in positions analogous to those 
along the Judicarian line, and the speaker had endeavoured to show 
that they were later than the Middle Kainozoic. 

Prof. Larworra pointed out that the Author recognized the 
existence of contemporaneous igneous rocks and tuffs in the 
Buchenstein-Cassian succession of Triassic age; but she claimed 
that the igneous rocks occurring in the fault-lines were intrusive, 
and were of Tertiary date. This paper was the result of several 
seasons of hard field-work in a critical area of the Dolomite country, 
by one who had previously made herself familiar with all the 
stratigraphical zones. He was himself prepared to accept her 
description of the complex folding and faulting in the area covered 
by her work in the field; and he looked upon her map and sections 
of that area as a most important and suggestive contribution to our 
knowledge of Alpine stratigraphy. 


Vol. 55.] THE GEOLOGY OF NORTHERN ANGLESEY. 635 


35. On the Grotocy of Nortaern Aneiesry. By C. A. MatLey, 
Esq., B.Sc., F.G.S. With an Apprnpix on the Microscopic 


Srupy of some of the Rocks, by Prof. W. W. Warts, M.A., 
Sec.G.S. (Read June 7th, 1899.) 


ConrTENTS. 
Page 
epbutroduetory Remarks ....0. 005. dscsdies sen sate ensemeeerdenenie oe csb ae 635 
II. Description of the Rocks............ Ae RUE RS 5 MO Re Rena ps arts 637 
(a) The Green Series. 
(6) The Northern Complex. 
(ec) The Ordovician Rocks. 
III. Relation of the Green Series to the Ordovician ............-+. 638 


(a) Palxontological Evidence. 
(i) Fossils north of the Green Series. 
(ii) Notes on the Northern Fossils. 
(iii) Fossils south of the Green Series. 
(iv) Conclusions from the Paleontological Evidence. 
(0) Stratigraphical Evidence. 
(i) Nature of the Boundary. 
(ii) Proofs of an Unconformity. 
(c) Conclusion. 
1V. Earth-movements and their Effects 
(a) Contortions and Folds. 
(6) Dislocations. 
(c) Cleavage. 
(d) Crushing. 
(e) Disruption. 
(f) The Crush-Breccias and Crush-Conglomerates. 
(i) Trwyn Pen-careg. 
(ii) Porth y Corwgl. 
(iii) The Cemaes District. 
(iv) Western part of the North Coast. 
(v) Dykes in the Crush-Zones. 
(vi) Method of Formation. 
(g) Age of the Movements. 


V. The Northern Complex and its Relation to the Ordovician... 667 
(a) Limestones. 
(6) Quartzites and ‘ Quartz-Knobs.’ 
(c) The Ordovician Rocks. 
(d) Relation of the Northern Complex to the Ordovician. 


BMPR STIR «ov alcw when ssnesn n/t sasnceee aden ee tack smadean ceepitan setiemaaains te 674 
VII. Appendix on the Microscopic Study of some of the Rocks ... 675 


I, Intropuctory REMARKs. 


Tue northern part of Anglesey contains a group of rocks regarding 
the age of which geologists hold divided opinions. As the well- 
defined district in which they lie occupies the north of the island, 
the strata taken as a whole are known as the ‘ Northern District 
Rocks.” From their frequently twisted and contorted aspect, 
Prof, Hughes calls them the ‘ Gnarled Series.’ These beds have a 


636 MR. C. A. MATLEY ON THE [ Aug. 1899, 


general dip to the north or north-east, and consist mainly of green 
chloritic schists and grits, and greenish-grey and purple phyllites, 
slates, and shales. They are everywhere bounded on the south by 
black slates and shales of acknowledged Ordovician age. ‘This 
boundary-line forms a curve running from coast to coast from near 
Carmel Head on the west through Llanfflewin to Porth y Corwgl on 
the east; it is shown on the 1-inch Survey map, and is considered 
by several geologists (among others, Ramsay, Hicks, Callaway, and 
J. F. Blake) as a line of dislocation—an ordinary fault according 
to Ramsay,’ or according to later writers as a thrust whereby 
the Northern District rocks have been pushed over the Ordo- 
vician beds. Ramsay? believed this northern area to be mainly 
altered Cambrian strata, with some Lower Silurian (Ordovician) 
beds in the northernmost parts near Cemaes,*? though he could 
not here separate the rocks of the two systems. Dr. Hicks’ con- 
sidered the beds north of the curved fault to be pre-Cambrian 
(Pebidian) ; Dr. Callaway ° also classified the beds as pre-Cambrian 
of the slaty (Pebidian) type. Prof. Blake’ concurring in the pre- 
Cambrian view, grouped the rocks into two sets:—the ‘Sedi- 
mentary Series’ and the ‘ Disturbed Volcanic Group,’ both of which 
he assigned to the middle part of his ‘ Monian System’; he also 
separated from them certain conglomerates and black shales in the 
northernmost part of the district as ‘ undoubted Ordovician.’ 

On the other hand, Prof. Hughes ® has long held the opinion that 
the supposed fault is either non-existent or of little throw, and that 
the barren green and gnarled strata of the Northern District are 
intermediate in age, as they are in position, between the black 
Ordovician slates of the south and those of the north. Dr. Roberts? 
supported this view, and in 1891 Sir A. Geikie also expressed his 
opinion * that the whole of the Northern District strata were of Bala 
age. This view finds expression in the recently-published Index 
Map of England and Wales (Sheet 7). 


1 Mem. Geol. Surv. ‘ Geol. N. Wales,’ 2nd ed. (1881) p. 236 & fig. 88. 

2 Ibid. pp. 234 & 242; Geol. Surv. Map, Sheet 78. 

3 This is the spelling adopted by the inhabitants and the postal authorities, 
but the village is called Cemmaes on the Ordnance maps. For all other 
names I follow the spelling of the 6-inch Ordnance Survey map. 

* Geol. Surv. Eng. & Wales, Horiz. Sec. Sheet 40. 

> «Pre-Cambrian (Dimetian, Arvonian, & Pebidian) in Caernaryonshire & 
Anglesey,’ Quart. Journ. Geol. Soc. vol. xxxv (1879) p. 295. 

6 « Archean Geol. of Anglesey,’ 2bid. vol. xxxvii (1881) p. 210; ‘Archean & 
Lower Palzozoic of Anglesey,’ 2bid. vol. xl (1884) p. 567. 

7 ¢Monian System of Rocks,’ zbéd. vol. xliv (1888) p. 514. 

8 «Altered Rocks of Anglesey, Proc. Cambr. Phil. Soc. vol. iii (1880) 
pp. 346-347 ; ‘Geol. of Anglesey,’ Quart. Journ. Geol. Soc. vol. xxxvi (1880) 

. 239. 
me Geol. Mag. 1881, p. 573. 
10 Pres, Addr, Quart. Journ. Geol. Soc. vol. xlvii (1891) Proe. p. 182. 


Vol. 55. | GEOLOGY 0¥ NORTHERN ANGLESEY. 637 


Il. Description oF THE Rocks. 


By far the greater part of the area is occupied by the set of strata 
called by Prof. Blake the ‘Sedimentary Series,’ in contradistinction to a 
‘ Disturbed Volcanic Group’ which forms a strip in the northernmost 
part. As, however, this disturbed group appears to be as sedimentary 
as the former, I use the term ‘ Green Series ’ for the prevailing strata 
north of the Ordovician boundary, because they are characteristically 
of a greenish tint, though they have purple and yellowish bands in 
them. The ‘ Disturbed Velcanic Group’ of Blake will for the present 
be called merely the ‘ Northern Complex.’ 


(a) The Green Series. 


A careful and graphic description of these rocks is given by 
Ramsay in the ‘ Geology of North Wales,’ the principal correction by 
later writers being to limit his use of the term schist. ‘The straia 
on the whole dip to the north or, in the western part of the area, to 
the north-east; but these directions are not constant, especially in the 
western part. For instance, in the neighbourhood of Pen-yr-orsedd, 
Caerau, and Nanner the beds have a south-easterly dip, and near 
Groes-fechan they form a low dome. Various writers have pointed 
out the characteristic types of rock. The highly contorted Mynydd 
Mechel! Schists occupy the centre of the curve of the boundary- 
fault ; in part they are thoroughly foliated and crystalline, in part 
they are very quartzose and distinctly gritty, and they appear to be 
grits and shaly beds in which a crystalline texture and foliated 
character has been developed, sometimes to the complete obliteration 
of clastic structure. Dr. Callaway has recently shown that the 
foliation is more marked and the crystalline structure more complete 
as we pass southward to the boundary-fault.. I am inclined to 
think that they are in part foliated representatives of the Llan- 
fechell Grits, a set of rather thickly-bedded green grits which 
succeed the schists to the north. 

With the exception of the beds in the extreme north of Anglesey, 
the country north of the Llanfechell Grits is occupied by green 
slates with purple zones and numerous coarser gritty layers. The 
Rhosbeirio Shales of Dr. Callaway—soft greenish, purple, and 
yellowish-brown shales in the centre of the district, with a constant 
northerly dip—form part of this series; and similar beds may be 
followed across the strike as far as Cemaes. To the east of 
Amlwceh they are extremely contorted or ‘gnarled.’ Grits (of 
a greyer type) again set in in some force in what appear to be 
the highest beds, along part of the northern coast, especially in 
the neighbourhood of Trwyn Cemlyn and Cerig Brith, and they are 
recognizable among the contorted beds near Point lianus. 

It is generally considered that these slaty and gritty deposits 
contain a certain proportion of volcanic dust and ash, and, though 


1 Quart. Journ. Geol. Soc. vol. liv (1898) pp. 374-381. 


638 ‘ «MR. CG. A. MATLEY ON THE [Aug. 1899, 


my microscopic slides have yielded very little evidence of this, I 
have found a rock containing some volcanic fragments in the series 
near Taldrws, Cemlyn. The detailed stratigraphy of this Green 
Series is very complicated, and requires working out ; but the succes- 
sion may be provisionally stated as below, in descending order :— 
(1) Cemlyn Flagegy Grits, Phyllites, and Shales. 
(=Llaneilian Beds in part.) 
. (2) Rhosbeirio and Cemaes Shales and Slates, with Grit-bands. 


=Llaneilian Gnarled Series in part.) 
(3) Llanfechell Grit and Mynydd Mechell Chloritic Schists. 


Numerous dykes and bosses cut through these beds. Some are 
acid, others basic, and ophicalcites and serpentines also occur. Their 
relationships are interesting, but do not come within the scope of 
this paper. 


/ 


(6) The Northern Complex. 
This group of rocks lies along the coast, north of a line running 
almost due east-and-west from Mynydd Wylfa to Bull Bay, passing 
a little north of Cemaes Pier. Among these rocks are some that 
correspond with the Green Series farther south, but the bulk havea 
very different facies. Prof. Blake says that this part of the district 
may be roughly described as ‘full of agglomerates, coarse ashes, 
quartz-knobs, limestones, and conglomerates.’* As some of these 
rocks owe their clastic appearance to crushing, their description 
may be more fitly left till the effects of earth-movements have been 
considered. 


(c) The Ordovician Rocks. 


These lie in the Northern Complex in strips and patches. They 
consist of conglomerates and pebbly sandstones, grey sandy shales, 
and black argillaceous shales with some ironstone. As they are 
found associated with the last-mentioned group, their fuller con- 
sideration wiil be also deferred to a later part of this paper. 


IIT. Renatrion oF THE GREEN SERIES TO THE ORDOVICIAN. 


The arguments for and against the Ordovician age of the Green 
Series fall under two heads—paleontological and stratigraphical. 


(a) Paleontological Evidence. 


The Ordovician age of the Green Series has been inferred, 
on paleontological grounds, from certain fossils mentioned as 
occurring near Craig Wen and in a limestone near Carmel 
Head. Prof. Hughes discovered Orthis Bailyana and other Orthides 
in the beds cut through by the tramway at Craig Wen. These 
beds are not, however, part of the Green Series; Prof. Blake 


? Quart. Journ, Geol. Soe, vol, xliv (1888) p. 517. 


Vol. 55: | GEOLOGY OF NORTHERN ANGLESEY. 639 


includes them in his ‘ Disturbed Volcanic Group,’ and claims the 
fossils as pre-Cambrian (Monian).' As I have found abundant 
examples of Orthis calligramma in these beds, they are un- 
doubtedly Ordovician ; but the determination of their age does not 
carry that of the Green Series with it. 

Sir A. Geikie mentions’ a fossiliferous limestone near Carmel 
Head as proving the Bala age of the green beds; but it is worthy 
of note that, though Ramsay recorded that ‘a few poor fossils ’* 
indicated a Bala age, his map shows that he was satisfied that the 
fossil-bearing bed was distinct from the Green Series. I have 
collected fossils from this limestone; but, as the relationship of this 
bed to the Ordovician and the Green Series is rather a question of 
stratigraphy, this point will be taken up again in dealing with the 
stratigraphical evidence. 

We will now compare the fossils that occur in the rocks north 
of the barren Green Series with those that are found south of 
that series, as this should throw some light on the succession. For, 
if we consider the green rocks to be conformably interbedded 
between the Ordovician on the south and the fossiliferous beds on 
the north, we assume a general ascending succession from south 
to north, and we therefore ought to expect that fossils found along 
the northern coast will belong to a higher zone than any horizon 
occurring in the southern rocks, 


(i) Fossils north of the Green Series. 


Fossils have been known to occur at three localities in Northern 
Anglesey, namely :—the tramway at Craig Wen, already mentioned ; 
Porth Padrig, near Cemaes; and in a limestone at another Porth 
Padrig, north-west of Mynachdy ; but Orthis Bailyana is the only 
fossil hitherto identified. 1 have succeeded in finding identifiable 
specimens in several localities, and append a list. 

(x) Porth Padrig. Black Shales.—Most of the forms have 
been sheared out of recognition, but I have collected the following - 
eraptolites :— 

Didymograpius superstes, Lapw. Cenograptus gracilis, Hall. 
Dicellograptus sextans, Hall. | Leptograptus sp. 
Climacograptus Scharenbergi, Lapw. Dicranograptus sp. 
Diplograptus euglyphus, Lapw. | 


(3) In the same beds, in the Vicarage grounds above the Porth, 
T obtained :— 


Paterula balcletchiensis, Dav. | Siphonotreta (2). 
Acrotreta sp. 


1 Quart. Journ. Geol. Soe. vol. xliv (1888) pp. 523 & 542; Geol. Mag. 1890, 
p. 312. [This statement requires some modification, as Prof. Blake pointed out 
in the discussion, and I willingly make the desired correction. In his paper 
of 1888 he regarded the Monian age of these beds as only ‘probuble,’ stating at 
the same time that, he was ‘quite ready, if possible, to receive the fossils as 
characteristic’ of his Monian system. | 

2 Pres. Addr. Quart. Journ. Geol. Soc. vol. xlvii (1891) Proc, p. 132. 

3 Mem. Geol. Surv. ‘Geol. N. Wales,’ 2nd ed. (1881) p. 229. 


640 MR. C, A. MATLEY ON THE 


[Aug. 1899, 

(y) Dicranograptus-beds of Penterfyn.—Near a cottage 
called Penterfyn, south of Ogof Gynfor, are small quarries in flaggy 
ironstone interstratified with black, often pyritous, shales, some of 
the layers of which are crowded with Dicranograptus :— 


Cenograptus gracilis, Hall. 
Cryptograptus tricornis, Hall. 
Dicellograptus intortus, Lapw. 
Dicellograptus sp. 

Climacograptus Scharenbergi, Lapw. 
Dicranograptus ramosus, Hall. 


Dicranograptus rectus, Hopk. 

Diplograptus teretiusculus, Tullb., or 
euglyphus, Lapw. 

Didymograptus sp. 

Lingula brevis, Portl. 


(6) At Ogof Gynfor, in pebbly grits, the following occur :— 


Orthis vespertilio, Sow. 

(Dalmanella) testudinaria, Dal. 

conjinis, Salter (?). 

—— calligramma, var, 
Salter. 

— (?),small species with simple ribs. 


Strophomena, cf. Stropheodonta imbrex, 
var. semiglobosina, Davy. 

Orthis or Rhynchonella (imperfect), 
large form with very strong ribs. 

Rhynchonella sp. 

Crinoid-ring. 

Trace of a trilobite. 


Carausit, 


(e) At 100 yards east of Ogof Gynfor, in similar beds :— 


Orthis vespertilio, Sow. 


_ | Rhynchonella sp. 
(?), small species with simple ribs. 


Lamellibranchs, ef. Ctenodonta. 


(Z) At 120 yards north of Ogof Gynfor, near the boundary-fault. 
Beds similar to 6 and e yielded Lingula, cf. tenuwgranulata, M‘Coy. 


(n) Craig Wen tramway. In ashy-looking flaggy beds Prof. 
Hughes found Orthis Bailyana, Dav. 


I have also obtained :— 


Orthis, ef. confinis, Salt. 
sp. 


Orthis calligramma, var. Carausii, 
Salter. 


(0) Limestone-blocks in Ordovician breccia, at the western Porth 
Padrig, north-west of Mynachdy, yielded :— 


Stenopora (Favosites) fibrosa, Goldf. 
Solenopora compacta, Bill. = Tetra- 

diwm Peachi, Nich. & Eth. jun. 
Prasopora Graye, Nich. & Eth, jun. ? 
Monticulipora sp. 


Operculum of a Maclurea like M, Lo- 
gam, Salt., or M. Peach, Salt. 

Large gasteropod, ? Maclurea. 

Crinoid-stems and ossicles. 

Cast of a portion of a trilobite 


Orthis, perhaps O. calligramma or resembling Jilenus. 


O. flabellulum ? 
? Operculum of a Maclurea resembling 
M. matutina, Hall. 


(ii) Notes on the Northern Fossils. 


The graptolites which have been identified by Prof. Lapworth 
and Miss E. M. R. Wood are all typical Glenkiln forms, and the 
black shales in which they occur may be assigned to the Upper 
Llandeilo, or the Lower Bala of some authors. The accompanying 
brachiopods, Lingula brevis and Paterula balcletchiensis, are also 


Weol./55..] GEOLOGY OF NORTHERN ANGLESEY. 641. 


Llandeilo forms. The latter species has hitherto been recorded, I 
believe, only in the Scottish Llandeilo. 

For stratigraphical reasons it is almost. certain that the pebbly 
sandstones of Ogof Gynfor and the neighbourhood lie below the 
Dicranograptus-beds of Penterfyn. All the species, too, occur as 
low as the Llandeilo, so that the Ogof Gynfor rocks may be looked 
upon as Upper Llandeilo. The commonest form in these beds was 
a small Orthis (? Zygospwra) with simple ribs, which I could not 
identify. The Zingula is large, 1 inch long by nearly 2 inch wide. 
Its frontal margin is missing, but in contour and size the specimen 
agrees with L. tenwigranulata. The fine granulation is not pre- 
served, owing to the coarseness of the matrix. 


It was most interesting to find, associated with these fossils, 
specimens of the so-called species Orthis Carausii, because the 
occurrence of this form in the Orthis-grits of Central Anglesey seems 
to be the principal reason why Prof. Hughes assigns the basement 
Paleozoic rocks there to the period of the Tremadoe Slates, though 
Dr. Callaway has questioned the correctness of this conclusion.’ It 
only occurs occasionally at Ogof Gynfor, but one band in the Craig 
Wen tramway-beds was crowded with casts of the shell, and 
single individuals are to be found in other parts of the tramway. 
I have examined a large number of specimens and compared them 
with Davidson’s figures and descriptions, and (by the kindness of 
Prof. Hughes) with specimens from Central Anglesey in the Wood- 
wardian Museum. The concentric lines of growth are not so well 
preserved, though this may be due to the nature of the matrix, 
and a few examples very slightly exceed the dimensions given by 
Davidson ; but the majority of the specimens are within those limits, 
and all of them, in number of ribs, relative convexity of valves, 
and internal characters, agree with Orthis Carausii. O. Carausu 
was separated as a distinct species from O. calligramma as much on 
account of its occurrence at a lower horizon (namely, Tremadoce and 
Lower Arenig) as from its smaller dimensions.” But we now see 
that in Northern Anglesey the Carausi-form occurs with O. testu- 
dinaria, O. vespertilio, etc.: that is to say, on the horizon of the 
ordinary calligramma-form ; and the last-named is a very variable 
shell, frequently blending into the Carausw-type. There does not 
therefore seem sufficient justification for their separation into distinct 
species, and I follow Salter’s first identification of this brachiopod 
as a dwarf variety of Orthis calligramma. 


It is evident that Orthis Bailyana is not pre-Cambrian, and we 
may with confidence accept Davidson’s statement that in Wexford 
(the only other locality where this species occurs) it is found with 
O. calligramma, O. biforata, Leptena sericea, and Favosites fibrosus. 
These are taken to indicate a Bala age in Wexford, but the Anglesey 
beds are more likely to be Upper Llandeilo. 


1 Quart. Journ. Geol. Soe. vol. xxxvi (1880) p. 238 & vol. xl (1884) p. 580. 
2 Davidson, Monogr. Pal. Soc. (1882-1884) ‘ Brit. Sil. Brach.’ Suppl. p. 183. 


OF J. G.S. Nos 219: Po 


642 MR. C. A. MATLEY ON THE [Aug. 1899, 


Mr. B. N. Peach has examined the fossils from the limestone- 
blocks of the western Porth Padrg, and sends me notes concerning 
them. The relationship of these blocks to the breccias in which 
they lie will be dealt with later (p. 647), but it may be at once 
mentioned that in Mr. Peach’s opinion the limestone cannot be of 
earlier date than Ordovician, and that it is in all probability of 
Llandeilo age. He has no knowledge of the occurrence of Stenopora 
SJibrosa below the Llandeilo, Opercula of the Maclurea matutina-type 
are very common in the Durness Limestone, both in Sutherland 
and Skye. M. magna, M. Logan, and M. macromphala, M‘Coy, are 
found in the Stinchar Limestone, Ayrshire, which is either upper- 
most Llandeilo or at the base of the Caradoc. At Mr. Peach’s 
suggestion, | sent some microscopic sections from this Porth Padrig 
limestone to Dr. G. J. Hinde, who has very kindly examined them 
and found that they contain Solenopora compacta, Prasopora Graye? 
(both these forms occur in the Craighead Limestones of Girvan), 
and a species of Monticulipora. 


(ii1) Fossils south of the Green Series. 


In the central area south of the Green Series the fossiliferous 
beds consist of basal conglomerates which rest unconformably on 
older rocks or are faulted against them, and pass up through sand- 
stones into black shales. The basal conglomerates and grits are 
locally rich in the Orthis referred by Prof. Hughes and Dr. Davidson 
to O. Carausu. Accompanying this species have been found frag- 
ments of trilobites considered by Dr. Woodward and Dr. Callaway to 
be Jlenus, Asaphus, and Ogygia, but by Prof. Hughes and Dr. Hicks 
to be Niobe and Neseuretus.' In several localities the black shales 
have yielded graptolites.2 The lowest horizon indicated by them 
in this central area is at Caemawr, where Didymograptus Murchi- 
soni occurs. From Llysdulas Chmacograptus cclatus has been 
identified; from Llanbabo Diplograptus (probably D. folcaceus), 
Dicranograptus ramosus, Climacograptus Scharenberyi, Dicellograptus 
Morrisi, and Leptograptus sp. From the black slates of Parys 
Mountain Monograptus gregarius and other species belonging to 
the MW. gregarius-zone (Lower Birkhill) were obtained. At 
‘Treiorwerth Henslow found some fossils, mostly brachiopoda, which 
Prof. Hughes with some hesitation has also referred to a Llandovery 
horizon. They appeared to the latter to include such forms as 
Atrypa marginalis, Strophomena rhomboidakis, Meristella angusti- 
frons, Orthides including O. calligramma (?) and var. plicata, Petraia 
elongata (?), and Nebulipora cf. lens. 

In other parts of Anglesey, cut off from this central area by out-— 
crops of pre-Cambrian rocks, fossiiferous Ordovician strata occur.’ 
Near Llangwyllog there are graptolites typical of the highest Arenig 
or lowest Llandeilo. In North-eastern Anglesey Mr. Greenly has 
found black-shale boulders with Climacograptus bicornis (?), and 

1 Quart. Journ. Geol. Sac. vol. xl (1884) pp. 579 & 589. 

2 Ibid. vol. xxxvi (1880) p. 288, vol. xxxviii (1882) p. 26, & vol. xl (1884) 


p. 580. 
® Ibid. vol. xxxvi (1880) p. 238 & vol. lii (1896) p. 628. 


Vol. 55. GEOLOGY OF NORTHERN ANGLESEY. 643 


recently he has recorded undoubted Arenig fossils (Didymograptus 
patulus, D. nitidus, D. eaxtensus?, Climacograptus?) from the Caer- 
narvonshire side of the Menai Bridge.* 

The sole evidence for assigning the basal Protozoic rocks of Central 
Anglesey to a Tremadoc horizon is the occurrence of the fragmentary 
and disputed trilobites mentioned on p. 642, and the presence of 
Orthis Carausu. Ihave shown that this brachiopod is found a few 
miles away in Llandeilo Beds. There is a marked absence of typical 
Arenig graptolites, such as Tetragraptus and Phyllograptus, and the 
lowest zonal graptolite, Didymograptus Murchisoni, indicates a Lower 
Llandeilo horizon. The evidence of Tremadoc age should therefore, 
as Dr. Callaway has already argued, be rejected until further proof 
be afforded. It is much more likely that the fossil-bearing beach- 
rocks of Central Anglesey are equivalents of the base of the 
Llandeilo, or the top of the Arenig, and there is in this area a 
succession through the Llandeilo and Bala into the Llandovery 
horizons noted at Treiorwerth and Parys Mountain. 


(iv) Conclusions from the Paleontological Evidence. 


We see, then, that the southern Ordovician contains fossils from 
early Llandeilo to the Llandovery. The northern Ordovician com- 
mences rather higher in the Llandeilo, and ranges perhaps into the 
Bala. The palzontological evidence is therefore distinctly opposed to 
the theory that the Green Series is of Bala age, interbedded between 
older strata on the south and newer strata on the north. That theory 
was first suggested by Prof. Hughes, at a time when fossils from 
the area were almost unknown, because he thought that it afforded 
a simple and natural explanation of the geological structure. But 
this simplicity of structure is shown by the fossils to be untenable. 
We have to imagine an almost complete inversion of the strata, and 
even then we have to account for the mysterious absence of the 
Green Series between the Llandovery and the basement-rocks of the 
central area. On paleontological grounds alone it seems necessary 
to abandon the theory; if not, we land ourselves in stratigraphical 
complexities far more improbable than those which the assump- 
tion of a Bala age for the Green Beds was intended to remove. 

The fossils bring out another point which is worthy of discussion, 
namely, that the conglomerate in Northern Anglesey seems to be ona 
higher horizon than the Ordovician base in Central Anglesey ; in 
the latter area it is below the zone of Didymograptus Murchisoni, 
in the north it appears to be well above that zone. This may be 
explained on the reasonable assumption of an overlap to the north, 
such as would result from a continuance of the conditions which 
caused the overlap of the successive horizons of the Cambrian when 
followed from Merionethshire northward. Anglesey seems to have 
remained dry land throughout the Cambrian period, and if its more 
elevated portion lay in the north of the present island when it was 
slowly submerged in Ordovician times, the old beach creeping up 
the slopes of the sinking land would there be of later date. 


1 Geol, Mag. 1898, p. 561. 
272 


644 | MR. C, A. MATLEY ON THE [Aug. 1899, 


(b) Stratigraphical Evidence. 


Not only is the paleontological evidence strongly against the Bala 
age of the Green Series, but stratigraphical considerations are equally 
conclusive, although some writers have adduced evidence that part of 
the boundary cannot be anything but a bedding-plane. That the 
Green Series is older can be demonstrated in two ways: (i) by an 
examination of the boundary, and (ii) by proofs of an unconformity. 


(i) Nature of the Boundary. 


The boundary is mapped by the officers of the Geological Survey 
as a simple curved line, broken south of Amlwch by a cross-fault. 
In so crumpled a region as Anglesey the simplicity of the dividing- 
line isin favour of its being a dislocation. Ramsay! inferred the 
necessity of a fault from the dying-out of the dykes at the junc- 
tion, and Blake” because the boundary brings together various parts 
of the two series. As Dr. Callaway*® has already examined this 
Junction, especially with reference to the eastern half, I have con- 
tented myself with examining it in that portion at only a few 
localities, but have devoted more attention to the western part of 
its course. At its eastern extremity, in the little cove of Porth y 
Corwgl, it is admitted to be faulted, and the hade seems to be 
steeply to the north. North of the break are the highly-crumpled 
or ‘gnarled’ green rocks; south of it are Ordovician slates, grits, 
and pebbly slates, which are so broken as to become in part a 
*crush-conglomerate.’ The movement producing the dislocation 
is therefore clearly one of compression. Dr. Callaway has pointed 
out that conglomeratic Ordovician beds fringe the boundary for 
about 2 miles; he suggests that we are near the base of the Black 
Slate Series, and that the Ordovician is here inverted. Prof. Blake 
has examined the two localities farther to the south-west, where 
Dr. Roberts* states that the Ordovician can be traced quite uninter- 
ruptedly into the Green Series, but he does not consider that the 
exposures justify the latter’s conclusions.? Nowhere did I find a 
passage between the two series. At Bothedd, where a passage has 
been suggested,’ the Ordovician black slates are interbedded with 
bands of grit and breccia whose green colour at first sight suggests. 
a transition ; but these bands are very distinct from the apparently 
overlying rocks, and owe their colour to the circumstance that they 
are largely made up of green fragments such as are found in the 
Green Series. A microscopic section (N.A. 49)" of one of these bands 
shows it to be a grit almost entirely made up of fragments of fine 
phyllites, generally sericitic, a few quartz-grains, and some chloritic 
shales. The clastic structure is not due to crush. The presence of 


* Mem. Geol. Surv. ‘Geol. N. Wales,’ 2nd ed. (1881) p. 235. 

2 Quart. Journ. Geol. Soc. vol. xliv (1888) p.514. ° Jbid. vol. xl (1884) p. 567.. 
4 Geol. Mag. 1881, p. 573. 

> Quart. Journ, Geol. Soe. vol. xliv (1888) pp. 515 & 529. 

6 Jbid. vol. xlvii (1891), Pres. Addr. Proc. p. 182. 

7 The numbers in parentheses are those of the slides in my cabinet. 


Wol.55.] . GEOLOGY OF NORTHERN ANGLESEY. 645 


these bands suggests again that we are near the overturned base of 
the Ordovician. Beds of very similar character occur in the black 
shales about 2 mile farther on, and also on the eastern slopes of 
Mynydd-y-Garn. 

It may be remarked that along most of the course of the fault 
the green beds are generally crumpled and crushed, the neighbour- 
ing black shales are frequently similarly affected, and small outcrops 
of white quartzite, evidently introduced by the movement, occasionally 
mark its track. 

At Caerau the fault splits; the more northerly branch brings in 
a V-shaped Ordovician outcrop north of Mynachdy, the north- 
westerly emerges at Porth yr Ebol. The former runs from Caerau 
through Mynachdy Lodge to Porth Newydd. For the first part of 


Fig. 1.—Eastern side of Porth yr Ebol. 


AB, CD=Intersecting thrusts. 1—Green flaggy slates, much crushed and 
brecciated. 2= Ordovician blue-black slates. 


its course the Green Series, represented here by a purple slate, is 
brought against the granite and altered rocks of Mynachdy, the 
characteristic bed along the junction being a white quartzite, but 
mingled with it are. patches of limestone, grit, blue and dark 
quartzite, and black shale. Farther north the Ordovician comes on, 
and the junction, though invisible, is unmistakably faulted. The dip 
and strike of the two series are discordant ; on the north side the 
beds are shattered by hundreds of tiny horizontal faults, and on 
the south the black shales are highly compressed, and courses of 
sandstone in them are squeezed into lenticles. 

The more westerly branch of the fault can be traced without 
difficulty from near Mynachdy to Porth yr Ebol, where it may be 
seen as an irregular synclinal curve in the cliff that forms the eastern 
side of the Porth (fig. 1). This undulating junction has caused it 


646 MR. C. A. MATLEY ON THE [| Aug. 1899, 


to be mistaken for a bedding-plane, but the bands in the two series. 
strike against each other. Its true character can be seen more 
plainly in a little creek that has been eroded at right angles to the 
trend of this cliff near its seaward termination, where the thrust 
AB can be seen rising steadily to the westward at an angle of 20°, 
and bringing the green beds over the younger Ordovician. This 
little creek has been eroded along another overthrust CD, which has 
here a nearly east-and-west course, and again brings up the Green 
Series. The thrust CD is a somewhat later movement than AB, 
and its pressure has bent the earlier thrust-plane, thus accounting 
for its synclinal curve. The green beds are highly crushed and so 
broken as to be practically crush-breccias, and are much rolled out 
near the junction. The Ordovician rocks are also much crushed 
(N.A. 89 & 90). 
The later thrust has here an inclination of 60° to the horizontal. 

Its course can be readily followed in a west-north-westerly direc- 
tion, first across the shore and then inland in front of the lower 


ory, Carmel 
aN 
SSS 


Pen bryn 
yr Eglwys Mynachdy 


a. Ny. 


Fig. 2.—Sketch-map of 
the North-western corner Shaded areas = Ordovician.. 
of ANGLESEY. Unshaded_areas= pre-Llandeilo. 


Scale: 2inches to 1 Mile.——~ 


beacon. Its inclination decreases to 30°, and continues to flatten, 
as shown by the course of its outcrop on the rising ground. It 
finally passes out to sea in the unnamed Porth south of Porth y 
Wig, where an almost level platform has been worn along the 
junction. The underlying beds are the Ordovician slates. The 
overthrust beds are greenish-grey gritty phyllites, as a rule highly 
contorted and smashed, and showing microscopically evidences of 
movement. They are ‘succeeded at Carmel Head by beds with 
broken limestone and quartzite, where they form almost a ‘ crush- 
conglomerate.’ In Porth Gron, hading north-west at 45°, can be 
seen another thrust forcing the Green Series over contorted grey 
Ordovician slates ; but perhaps enough detail has been given to 
prove that the asserted interstratifications of the two series are the 
deceptive results of earth-movements. Fig. 2 shows the course of 
the principal faults and thrusts in this corner of the island. 


lard 


Woll.55: || GEOLOGY OF NORTHERN ANGLESEY. 647 


There still remains the point brought forward by Sir A. Geikie, 
that a limestone with Bala fossils exists on the shore in the north- 
western part of the island, and that it forms part of the Green 
Series. This limestone occurs in the Ordovician tract near Mynachdy, 
at the base of the Black Slates in a cove called Porth Padrig.’ It 
is not found as a bed, but as abundant limestone-blocks, more or 
less rounded, lying in a thick greyish breccia, below which lies a 
patch of black shale, and streaks of this shale run up in irregular 
strings into the limestone-breccia, denoting considerable dis- 
turbance. Above this breccia are black shales of the ordinary 
Ordovician type, with which are interbedded several breccia-bands. 
These thinner breccias also contain limestone-blocks, some almost 
as thick as the bands in which they lie. The coarse fragmental 
deposits in which the limestone-masses occur appear to be the local 
equivalents of the basal conglomerates of Ogof Gynfor and Porth 
Llanlliana, and therefore may be considered of Upper Llandeilo 
age, while the limestone-fossils, according to Mr. Peach, are also 
Upper Llandeilo. Although, therefore, the limestone-blocks look 
like pebbles and boulders of ordinary clastic origin, the palsonto- 
logical evidence is against this view, and we seem to be confronted 
with the same phenomenon as in beds of about the same horizon in 
Southern Scotland, where limestone-nodules of contemporaneous 
age lie in the midst of conglomerates. This confirms Ramsay’s 
conclusions” respecting this limestone, as he speaks of these masses as 
‘irregular bands,’ ‘ thin irregular bands,’ and ‘ concretionary half- 
crystalline limestone.’ In their lower part they may also have under- 
gone some breaking-up by movement. Mr. Peach adds the following 
to his notes respecting the fossils from this locality :—* From what 
I have seen of the limestones in the Southern Uplands of Scotland, 
T should think that this limestone is of approximately the same date 
as the conglomerate in which it occurs: that is, that the liimestone- 
masses are not derived pebbles, but that they are in some way 
formedin place. The manner in which the quartz-pebbles 
are enclosed in them points to this conclusion. The Stinchar Lime- 
stone, where it thins out, is represented as a series of knots or 
masses in the heart of the Benan Conglomerate with which it is 
associated. The same is the case with the limestones of Wrae and 
Glencotho, and also with the fossiliferous conglomerates of Kilbucho 
and Duntercleuch in the Lead Hills, where the fossils are found in 
calcareous concretions and masses similar to these limestone-knots.’ 

These inconstant nodules are therefore Llandeilo limestones lying 
in Ordovician breccias. They do not form part of the Green Series, 
nor can we correlate them with the Cemaes limestones. The latter 
are unfossiliferous, differ in texture, weather in a different way, and 
retain their characteristic appearance in an exposure at Carmel 
Head not very far from the outcrop of this Llandeilo rock. The 
presence of these fossils, therefore, throws no light on 
the age of the Green Series. 


1 Not to be confounded with the larger Porth of the same name near 
Cemaes. 


2 Mem. Geol. Surv. ‘Geol. N. Wales,’ 2nd ed. (1881) pp. 229, 242, & 246. 


648 MR. C. A. MATLEY ON THE [ Aug. 1899, 


Gi) Proofs ‘of am 
Unconformity. 


The evidence detailed in 
the foregoing pages affords 
ample proof that the Green 
Series is older than the re- 
cognized Ordovician rocks 
of the district. It remains 
to be seen whether the 
two sets are conformable 
or unconformable to each 
other. If unconformable, 
we may hope to find some- 
where the Ordovician 
(1) lying on the denuded 
edges of the Green Beds, 
or (2) containing frag- 
ments derived from them. 
An example of the first 
kind has been instanced 
by Prof. Blake at Ogof 
Gynfor, and of the second 


200 yards). 


Pre-Llandeilo rocks of the Northern Complex. 


* by Dr. Callaway in the 
s included fragments of the 
‘Ss conglomerates of Pyttiau 
= near Llaneilian.’ 

CS Ogof Gynfor lies on the 
al north coast near Llanba- 


drig, among the rocks 
which I have called the 
Northern Complex. 
There is a consensus of 
opinion that the rocks 
occurring here are an up- 
ward continuation of the 
Green Series: so that, if 
there is an unconformity 
of the Ordovician in re- 
spect te this northernmost 
group, there must be a 
still greater unconformity 
with regard to the Green 
Series. I have ventured 
to produce a figure of 
the coast-section (fig. 3), 


Section at Oyof Gynfor, near Llanbadrig : (length 


Fig. 3. 


Conglomerates and sandy shales (Llandeilo). 


\ 


we 


ES ex . . 
3. «partly because it illus- 
esses — trates how very broken 


even the Ordovician beds 
are, and partly because it 


1 Quart. Journ. Geol. Soe. 
vol. xliv (1888) p. 519 & vol. xl 
(1884) p. 568. 


Rol. 5. GEOLOGY OF NORTHERN ANGLESEY. 649 


shows some very interesting and unmistakable examples of thrust- 
planes. The section, which extends farther south than Prof. Blake’s 
figure, differs from his in some respects, but differences may well 
be expected, for the section has to be constructed piecemeal as it 
is slowly revealed by scrambles over the rocks. Parts of the 
section are inaccessible, and some of the details are doubtful, but 
in its main features it will be found correct. 

The Ordovician beds occupy a faulted syncline, overthrust on the 
north, as Prof. Blake has pointed out, by limestone-beds. That the 
fault is an overthrust one is rendered unmistakable by the series of 
small thrust-planes which branch from the main fault, and clearly 
indicate that the basal conglomerates have been moved in successive 
steps across the succeeding sandy shales. The uppermost plane re- 
presents a travel of about 15 feet, and the curling round of the broken 
edges of the beds to lie in the plane of movement is well exhibited. 
These conglomerates are seen in one place to lie on greenish gritty 
phyllites which contain bands of fine grit and white quartzite. The 
junction is undulating; there has certainly been some movement 
along it, and the underlying rocks (N.A. 46 & 47) are highly crushed 
and have become augen-sericitic schists or phyllites. These changes 
seem, however, to have taken place to some extent before Ordovician 
times, as pieces of sericite-schist occur in the conglomerates, and I 
think that the relationship of the beds really represents an uncon- 
formity. Moreover, at the head of the gulf the conglomerate lies 
against a white quartzite: pebbles in the former appear to be 
derived from the latter; and the same relation between quartzite 
and quartz-conglomerate is to be seen at other localities in the 
neighbourhood, as well as on the headland of Porth Llanlliana. 
The conglomerates are largely made up of white quartz and quartzite- 
pebbles, which closely resemble the ‘ quartz-knobs’ of the vicinity, 
and they contain also occasional identifiable fragments of green slate, 
limestone, and other rocks that occur zn situ close by. 

Dr. Callaway found a similar assemblage in the conglomerates 
fringing the boundary-thrust at Pyttiau, but there they contained 
an abundance of limestone-blocks which corresponded exactly with 
the Cemaes limestone. The phenomenon of Llandeilo limestone- 
masses in the basal breccias at the western Porth Padrig must, how- 
ever, make us very cautious in accepting the presence of calcareous 
inclusions as proof of an unconformity. 

Perhaps, however, the most convincing proof is to be derived 
from an examination of the geologieal structure of Mynydd-y-Garn, 
a faulted inlier, mainly of contorted beds of the Green Series, lying 
in the midst of Ordovician ground. The summit and the eastern part 
of the hill are built up of a massive and crushed coarse conglomeratic 
breccia, which passes up, through slates interbedded with breccia and 
egrit-bands, into the ordinary black shales of the Ordovician. This 
massive breccia is the result of the denudation of granitic, gneissose, 
and schistose rocks, granulites, grits, etc.: indeed, such an assemblage 
as may be found i sitw on Pen Bryn-yr-Eglwys, 2 miles distant. 
The southern part of the inlier contains typical beds of the Green 


650 ! MR. C. A. MATLEY ON THE [ Aug. 1899, 


Series, consisting of highly crumpled, green, altered slates, agreeing 
closely with some seen near Llanfair-y’nghornwy Rectory, about 
? mile away. At the southern boundary the Ordovician black slates 
can be seen dipping into the hill, and there appears to be an inver- 
sion accompanied by a thrust, the emergence of which sweeps round 
the south of the hill to the western side, where it merges into and 
may form part of the fault that here too brings the Green Series: 
and the Ordovician ground into juxtaposition. At the south-eastern 
extremity, in the yard of the cottage called Cefn-du-mawr, the 
black shales which dip into the hill are interbedded with numerous 
bands of a green breccia unmistakably made up of fragments 
of the green altered slates. These fragments, like the parent- 
rocks, are in the condition of sericitic phyllites, and afford the 
clearest evidence that the Green Series had not only been exposed 
to denudation in Middle Ordovician times, but that the green rocks. 
had even at that period undergone considerable alteration. 


(c) Conclusion. 


Both paleontology and stratigraphy make it impossible to arrive 
at any other conclusion than that the Green Series is older than the 
recognizable Ordovician. ‘The disposition and dip, and even the 
apparent interstratifications of the rock-groups, are no guide to the 
true structure of the district, which is comparable in these respects: 
with such regions of powerful earth-movements as the Alps, the 
Scottish Highlands, and other mountain-ranges. The barren green 
rocks have been brought up and driven southward over black 
Ordovician and perhaps even Silurian slates by a great thrust which 
extends from sea to sea in a sweeping curve. This thrust is steeply 
inclined at its eastern end; at its western end it shows the low 
slope characteristic of the thrust-planes of the North-western 
Highlands. I have instanced other thrusts of varying hade which 
also bring the Green Series over the Ordovician, while the latter is. 
elsewhere seen to lie with a strong unconformity upon the green 
beds and to contain fragments derived from them. 

As to the actual age of the Green Series, all that Northern 
Anglesey teaches us at present is that these beds are older than the: 
Llandeilo, and had been subjected to alteration, foliation, and denu- 
dation before Upper Llandeilo times. Geologists who have worked 
over the whole of Anglesey find,them to agree so closely with rocks. 
in other parts of the island, which they consider pre-Cambrian, that 
a similar age for the Northern Anglesey rocks must be provisionally 
conceded. 


LV. EaRtTH-MOVEMENTS AND THEIR EFFECTS. 


The foregoing account will have made it evident that Northera 
Anglesey is a region affected by powerful earth-movements that 
have bent, folded, broken, crushed, contorted, and overturned the 


Vol. 55-| GEOLOGY OF NORTHERN ANGLESEY. 651 


strata ; in certain parts there is also extensive ‘disruption of the 
beds, resulting in the phenomena known as ‘ crush-conglomerates.’ 
These various effects will now be considered. 


(a) Contortions and Folds. 


In the south of the district the chloritic schists of Mynydd Mechell 
are thrown into contortions which are everywhere visible in the 
bare rocky hills which they occupy. The individual folds, though 
small, are not as a rule sharp, nor do their axes seem confined to 
one particular direction. In the north-east, stretching for several 
miles along the coast between Amlwch and Point Ailianus and 
extending southward to the bounding thrust, is another and more 
sharply-contorted area, described by Ramsay and other writers. 
Beds of the same character, and showing similar fine contortions, 
occur elsewhere, as for example near Llanfair-ynghornwy Rectory 
(see fig. 4), where the beds have a beautiful damascened appear- 
ance. Here, as in most cases, the axes of the folds slope in the 


Fig. 4.—Contorted green phyllites: part of rock-face in quarry 
behind Rectory, Llanfair-y’nghornwy. 


WE. 


Y \\ AN \n 
RO AY 
: \ \\ \ 
VIS 
SW |) 
WN We} \ 
ON} 


YN AR 
WAAAY 


same direction as the dip, and the inference from this general 
southerly to south-westerly tilt of the crests of the anticlines is 
that the region has been affected by a powerful push acting asa 
whole from the north: a conclusion which is in harmony with the 
general structure of the district, as developed in the first part of 
this paper. 

Even where the dip is at first appearance quite steady, a close 
examination or more favourable exposures will show in some cases 
that small contortions interfere with the apparent steadiness. 
An example of this may be seen in the Rhosbeirio Shales of 
Bodewryd Newydd quarry, and I have noticed a number of other 
instances, some in the neighbourhood of the crush-conglomerates. 
Between Trwyn Pen-careg and Cemlyn there is continual over- 
folding to the south and consequent repetition of the beds; here too 
are instances of folds in which the axes are almost horizontal. 


G52 MR. C. A. MATLEY ON THE [ Aug. 1899, 


In the region north of Cemaes the rocks have mostly been 
smashed instead of forming contorted folds, but in the shaly 
limestone of Pig y Barcud and elsewhere there are beautiful con- 
tortions on a small scale. The intensity of the folding may be well 
seen in the large limestone-quarry of Trwyn y Pare. This lime- 
stone exhibits in the mass no definite dip or strike, and bedding can 
rarely be made out, except where a coal-black crushed band of 
shale twists about on the south side of the quarry, or where thin black 
carbonaceous films make the structure evident. The limestone has 
the appearance of being built up into vertical prisms, and, save for the 
colour of the rock, the observer might readily imagine that he was 
looking at a quarry of basalt exhibiting vertical columns and joints. 
Though the structure of the massive limestone has been largely masked 
by jointing, etc., two remarkable folds in the quarry show that it has 
also been intensely folded. These folds face each other on opposite 
sides of the quarry. That on the north side shows the junction of 
the limestone with the overlying beds, which are represented by 
broken shaly material weathered into a muddy mass. The lime- 
stone has been curled up on every side into a basin-like fold with 
vertical sides, in shape like the bowl of an egg-cup or wine-glass, 
which would be better seen if the soft shaly stuff in the interior 
were scooped out. The axis is vertical and the curving-in of the 
encircling wall of limestone to form the base of the cup can be 
well seen. The diameter of this fold varies but slightly, say, from 
4 to about 43 yards. The front has been quarried away, and 
the upward continuation of the fold has also been removed by 
quarrying or denudation. The second fold, which is similar but not 
so regular, is to be seen 30 yards to the south on the opposite side of 
the quarry, and this too is filled in by a weathered mass of broken 
yellowish-green and black shaly material with less weathered 
harder pieces that represent the strata succeeding the limestone. 

Such folds as these cannot be produced by earth-movements 
acting in any single direction. We must have a combination of 
forces acting either simultaneously or consecutively in at least two — 
directions, and these directions, if only two, would have to be at 
right angles toeach other. One of the folding forces may be taken 
as having acted transversely to the north-and-south line that joins the 
centres of these two.folds, that is, in an easterly or westerly direction. 
This leaves for the second force the movement from the north to 
which reference has already been made. 


(6) Dislocations. 


Faults form so commonly the junctions between the rock-groups as 
to make the relationship of the various strata to each other a matter 
of extreme difficulty. The section at Ogof Gynfor (fig. 3, p. 648) 
affords a good instance of the terribly fractured nature of even the 
Ordovician rocks of the district. It exhibits normal faults, reversed 
faults with a more or less curved fracture, and gently sloping thrust- 
planes. We have already seen instances of dislocations on a larger 


Wool s5. | GEOLOGY OF NORTHERN ANGLESEY. 653° 


scale in investigating the relations of the Green Series to the Ordo- 
vician, and similar dislocations of the rocks are common in the 
Northern Complex of Cemaes and Porth Wen. The older rocks here 
crop up in strips between newer beds, and are bounded on one side 
by a normal, on the other by a thrust-fault. I have detected a 
number of each kind in the cliffs of the north coast, and others are 
interred from the stratigraphy. The line of fracture of the reversed 
faults as exhibited in coast-sections is often not straight, but a more 
or less sigmoidal*curve, and overfolds can be sometimes seen in 
connexion with them. One such broken overfold is visible in bedded 
quartzites, south of the graptolitic shale of Porth Padrig, and 
another example is seen in the ‘ quartz-knob’ at Llanbadrig Point 
(Irwyn y Buarth); see fig. 5. Of this knob Prof. Blake? says 


| : 
aj |) 
W J i 


Fig. 5.—Section*in quartz- 


knob, Llanbadrig Povnt. 


[Heavy lines denote shear=-plaxes.] 


1 = Quarizite. 

2 = Slaty beds with broken 
pieces of limestone (= 
crush-conglomerate). 


‘the phenomena here are those of ordinary faulting, resulting, not 
from pressure, but from tension. We cannot get this quartz-knob 
into its place by folding.’ But an examination of the quartz-rock of 
this small headland shows several polished planes of shear which curve 
down into the sea and along which the waves have found lines of 
weakness. Out of these curving shear-surfaces curve other surfaces 
of shearing. The neighbouring rocks are crush-breccias and the 


2 Quart. Journ. Geol. Soc. vol. xliv (1888) p. 518. 


654 MR. C. A. MATLEY ON THE [ Aug. 1899, 


section indicates to my mind not ‘ ordinary faulting resulting.... 
from tension, but thrust-faulting due to pressure. 

In connexion with the overfolding mentioned as occurring around 
the shores of Cemlyn Bay, there seems to have been plenty of 
shearing movement on a small scale at an angle agreeing with or 
only slightly oblique to the bedding. It is often difficult actually 
to prove this, although some of the planes are unmistakable. 
Movement gently oblique to the beds is inferred from the curious 
* wedging-out’ of individual strata when followed either along the 
dip or the strike. Individual laminze are seen to terminate along 
some of these planes; this pro- 
duces an appearance of false Fig. 6.—Porth Newydd: small 
or current-bedding, but it is horizontal faults in the cliff north 


due, I think, to the trunca- of the Ordoviccan boundary. 
tion of the lamine by shear- | “i 
planes. 7 
There are other horizontal [J 
faults which indicate a general 7 
shaking and shattering of the abt 
beds rather than a movement fL= 
in a definite direction. Such Ly 
are the tiny dislocations al- 
ready mentioned near the (ja 
Porth Newydd fault, where oe 
hundreds of them are revealed |_| 
by the banding of some nearly | 
vertical beds. A small por- [ 
tion of a rock-face exhibiting a 
twenty-eight of these miniature | 
faults is shown in fig. 6. Sy 
ales 
(c) Cleavage. . “TH 
The phenomena of cleavage fi 
haye not been closely studied, a a 
but a few points may be //] 


brought forward. Though the 
rocks bave been subjected over 
the whole of the area to close [Distance between bands=about 1 inch. ] 
compression, yet it is only in 
a few localities that they are seen to split obliquely to the bedding. 
The black shales of the Ordovician around Carmel Head are sometimes 
changed to argillaceous slates, and the coarse, black-banded, grey, 
sandy shales (also Ordovician) of Llanlliana and the neighbourhood 
are similarly cleaved, but less perfectly. Along these planes quartz- 
veins frequently appear. Even the conglomerates have been affected, 
and new structural planes are seen to cut across the bands of 
pebbles and determine the splitting of the mass. 

The strike of the most evident cleavage is more or less east-and- 
west, but does not always agree with the strike of the rocks. In 


Vol. 55.] GEOLOGY OF NORTHERN ANGLESEY. 655 


the area north of Craig Wen, where folds in the conglomerates and 
grits are often concealed by cleavage-planes, I noticed a divergence 
of some 15° between cleavage-strike and bedding-strike. Weathering 
sometimes brings out other systems of close-jointing, which may be 
earlier cleavages more or less obliterated by the pressure which 
produced the principal cleavage. or instance, the limestone and 
jaspery masses in the ‘crush-conglomerates’ at Penrhyn, near 
Cemaes, have such a set of vertical planes at right angles to the 
already-noticed cleavage-strike. A third set is sometimes noticeable 
agreeing in strike with the principal cleavage, but dipping north- 
ward at a much gentler angle. The facts suggest a series of move- 
ments in Anglesey very similar to those that produced the three 
cleavage-systems noticed by Mr. Lamplugh in the Isle of Man; but 
the point requires further attention. 


(d) Crushing. 


In the ordinary parallel cleavage described under the last head 
there is little or no sliding movement, the particles of the rock 
retaining as a whole the same position relatively to their neighbours 
before and after the compression. A further stage in the effects of 
- eompression is the differential movement of the molecules of the 
rock, causing them to slide past each other, and resulting as a rule 
in a phacoidal structure and a wavy cleavage. This breaking-down 
of the origina! structure by shearing movements is usually accom- 
panied by a development of a micaceous mineral, such as sericite, 
that renders the divisional planes glossy. Hard and resistant 
fragments included in the rock tend to be pulled out into phacoids, 
or to be rolled out into strings, or to break up into minor fragments. 
All stages up to complete mylonization may be observed. 

The breaking-up of rocks into phacoids is best known on the 
minute, but occurs also on the macroscopic scale. A good example 
is to be seen south of the graptolitic shales of Porth Padrig, in a 
yellowish-brown sandy rock. Again, a mass of limestone on the 
coast 250 yards north of Ogof Gynfor is similarly divided by 
curved joints into lenticles. These are not by any means solitary 
instances. 

On the smaller scale we have an ‘ augen’-structure developed in 
fine grits, as, for example, in Porth Padrig (underneath a broken 
overfold, N.A. 9) and in the older beds of the Ogof Gynfor uncon- 
formity (N.A. 46 & 47). Similar structures are common north of 
Craig Wen, and interbedded with the Craig Wen quartzite are shales 
which in part are practically mylonites (N.A. 43). 

Compression and shearing have had a marked effect on some of the 
conglomerates of the northern coast, and the results may be studied 
on both sides of Porth Wen Bay and in some localities inland. The 
pebbles have been sometimes flattened, sometimes pulled out into 
long phacoids or even strings of quartz or quartzite, at other times 
chopped into pieces by parallel planes of movement and thoroughly 
brecciated. 


656 MR. C. A. MATLEY ON THE [Aug. 1899, 


(e) Disruption. 


Instances of the partial breaking-up of bands of rock may be noted 
outside the bounds of the crush-conglomerates themselves. An 
excellent example is to be seen in the Ordovician of Porth Newydd, 
a cove situated north-west of Mynachdy, near the western end of 
the Northern District boundary-fault. The ordinary black Ordo- 
vician shales are here interstratified with courses of grit, and the 
breaking-up of these grit-bands is shown in the cliff in the clearest 
manner. The appended sketch (fig. 7) shows that these courses are 


Fig. 7.—Disrupted grit-courses in Ordovician black shales, 
Porth Newydd. 


[The two lowest grit-bands are introduced from another part of the section. | 


broken into longer or shorter pieces, lying quite dissociated one from 
the other, and strong transverse cracks indicate the commencement 
of further disruption. The ends of some of the pieces are pointed, 
those of others bluntly rounded. One of the bands has become a string 
of phacoids or lenticles, which a very little more pinching would have 
separated into distinct pieces. The shales have a general undu- 
lating dip to the north, and would not of themselves have suggested 
that the strata had been subjected to such powerful forces as those 
to which the disrupted grits testify. A little farther south more 


EE ae EL GO EE a aa 


Wol.-55.\| GEOLOGY OF NORTHERN ANGLESEY. 657 


complete disruption is observed, the pinched-out bands being there 
separated into distinct lenticles. A microscopic slide (N.A. 56) 
cut from near the surface of one of the bands figured in the sketch 
shows that the grit is considerably crushed and schistose. 

In the example just given the grit-courses do not exceed a few 
inches in thickness, but disruption of thicker beds of Ordovician 
grits has taken place at the eastern end of the district, south of the 
bounding fault at Porth y Corwgl. Im the face of the quarries 
south of the Porth may be seen, lying at intervals in the Black 
Slates, discontinuous masses of grit; they are evidently parts of 
bands similar to those seen a little farther north, which are clearly 
interbedded with the slates. Similarly-shaped isolated bands of 
conglomerate are shown by Prof. Blake in his figure of Porth Wen, 
west side.* 

North-west of Cemaes Pier, near Penrhyn, the fine slaty shales 
contain numerous thin layers of tougher or more indurated material, 
which, if followed for a few inches, are seen alternately to thicken 
and thin in a lenticular way and quickly die out. This irregu- 
larity of bedding seems best explained as an example, on a smaller 
scale, of the disruption exhibited in Porth Newydd. Fig. 8 (p. 658) 
shows this breaking-up in a small overfold. 


(f) The Crush-Breccias and Crush-Conglomerates. 


The completely disrupted strata known as ‘ crush-conglomerates ” 
may be looked for, if we take the Manx examples as our guide, 
along zones of powerful crushing, especially in areas where the soft, 
fine-grained, slaty rocks alternate with tougher and more brittle 
strata, such as grits and quartzites. Most of the crush-conglo- 
merates which I am about to describe are indeed formed mainly of 
lumps of hard quartzose beds in a finer matrix, and in some cases 
they can be traced into areas where these harder portions form 
recognizable interbedded bands. The occurrence and significance of 
such beds in Anglesey seem to have been recognized to some extent 
so long ago as 1880 by Prof. Hughes (although he does not 
specify any localities) in his paper ‘On the Altered Rocks of 
Anglesey.’ The following extract* has most bearing on the subject :— 
‘ When on a small scale nodules, or on a large scale masses, of hard 
rock lying in compressible shale are subjected to contortion, the 
shale is squeezed out over the harder masses, producing a kind of 
fault all round between the harder and softer rock, and giving rise 
to slickensides and similar phenomena, and often mineral changes 
are set up along the parts thus more crushed. In the case of a 
crumpled and gnarled shale in which there are thin lamin of 
harder and softer beds, this unequal yielding must produce similar 
results, and a kind of slickensides must pervade the whole mass.’ 

Some of these rocks were described by Prof. Blake in 1888 as 
volcanic agglomerates, and were included by him in his ‘ Disturbed 


1 Quart. Journ. Geol. Soc. vol. xliv (1888) p. 521, fig. 23. 
2 Proc. Cambr. Phil. Soc. vol. iii (1880) p. 344. 


@..J. G. 8. Nae Zig: Qu 


Vol. 55.1 THE GEOLOGY OF NORTHERN ANGLESEY. 659 


Volcanic Group.’ He remarks upon their unusual features, in some 
localities especially, as in Porth Wnol, where ‘there is wild con- 
fusion in the rocks. The most remarkable feature is the occurrence 
of great quartz-lumps, which are of all sizes and shapes, and lie 
promiscuously in agglomerates of slates, grit, and dust...... They 
must have been in existence previous to the formation of the 
agglomerate, which we cannot here refer to the action of a crush- 
faulty... |. . In the headland of Pen-y-pare we get another agglo- 
merate of quartz-lumps and ash.’* 

In 1896 Sir A. Geikie, in a short communication to the British 
Association, announced ” that he was convinced, in the light of the 
Manx examples, that these breccias are crush-conglomerates, pro- 
duced by the breaking-up of stratified rocks (mainly grits and 
slates) in situ. The limestone-masses he refers to the disruption 
of some of the limestone-bands of the neighbourhood. He, however, 
points out that the strata which have been disrupted are largely 
composed of volcanic detritus, so that the arguments he originally 
based on the volcanic nature of these beds are not disturbed. 

Prof. Blake has expressed his inability to concur in this ‘ crush- 
conglomerate’ theory, mainly on the ground that the Anglesey 
agelomerates are composed of ‘a variety of rocks not like those of 
the immediate neighbourhood.’ ® 


(i) Trwyn Pen-careg.—The example of a crush-conglomerate 
that will be first noticed is to be found on Trwyn Pen-careg, a head- 
land east of Cemlyn Bay, and it is selected for first description 
as il occurs here in its simplest form and offers an intermediate 
stage between the broken grit-bands of the Ordovician of Porth 
Newydd and the more complicated disruption to be seen west 
of Cemaes. Immediately north of Trwyn Pen-careg lies Cerig 
Brith, with which the headland is connected by a shingly beach 
when the tide is low. The promontory of Trwyn Pen-careg itself 
terminates in a small cliff of crush-conglomerate of a somewhat 
rudimentary character. it consists of greenish-grey slaty and gritty 
beds, such as are seen on Cerig Brith, but broken into fragments. 
Most of the pieces are angular, but some are rounded sufficiently to 
be considered ‘ pebbles,’ and their surfaces are covered by a glossy 
sericitic mineral developed by the shearing. The ‘pebbles,’ or 
authiclasts as they may be termed, are mostly small, one of the 
largest noticed measuring 15x 6x9 inches; but much larger masses 
_of almost unbroken beds lie among the brecciated fragments. Some of 
the purple slaty bands of the locality are included in the crush-zone. 
Pieces of the purple rock lie among the green fragments, and by the 
contrast of colour emphasize the fragmental character of the mass, 
but on the whole the purple ‘ pebbles’ are localized in definite parts 
-of the breccia, thus showing that the amount of relative displace- 
ment has been small. 

The area of disruption is narrow and short. South of it we 
find similar, much contorted, and overfolded greenish and purple 
1 Quart. Journ. Geol. Soe. vol. xliv (1888) pp. 517-518. 

2 Geol. Mag. 1896, p. 481. 8 Ibid. p. 570. 
20 2 


660 MR. C. Ag MATLEY ON THE [Aug. 1899, 


phyllites. The ex- 
posure is important. 
in that it is not 
complicated by lime- 
stones and quartzites. 
as in the crush-zones- 
nearer Cemaes, nor 
has the crushing so: 
completely disinte- 
grated the beds as 
in that area. We 
have here a zone of 
rocks identical in 
composition with the. 
contorted beds on 
either side of it, 
consisting of those 
beds brecciated and 
displaced, and with 
some of the frag- 
ments more or less 
rounded; it is evi- 
dently authiclastic 
in origin. 


oS 


ly to the strike, with a senndragranmatic 


(Length = about 500 yards.) 


oct 
¢ 


aque 


Quartzose and jaspery rocks. 
[The portion at X is the rock-face shown in fig. 10, p. 662. ] 


Q= 


Gi) Porth 
Corwgl.— At the 
extreme east of the- 
Northern District 
the thrust between. 
the Ordovician and 
the Gnarled Series: 
reaches the coast 
at Porth y Corwegl.. 
Black shales occur: 
immediately south 
of the junction, but 
within a few yards 
they are interstrati-- 
fied with grits of 
various degrees of 


h the crush-conglomerate, obl 
lds. 


uy) 


suggestion’ of the overfo 


Cemaes: section throu 


Dykes, of later date than the folding. 


S coarseness, and some- 
= of the shales also 
= take on a_pebbly. 
4 character. The grits 
Hit idently int 
G.q are evidently inter- 


bedded, but at the 
southern end of 
the Porth they are 
much disrupted and 


Fig. 9.—Coast, Penrhyn, 


Vol. 55.] GEOLOGY OF NORTHERN ANGLESEY. 661 


lie in lenticular patches among the shales. Pieces of these grit- 
beds form ‘ pebbles,’ often with slickensided surfaces; and angular 
fragments of the shale, pebbles of quartz and grit, and these 
“ pseudo-pebbles ’ are all felted together into a solid rock. Most of 
the pebbly shales seem to have been, on the whole, formed in the 
ordinary way by the denudation of older rocks. To the south the 
slates return to their ordinary character, but bands of grit lie more 
or less isolated, showing that there is still disruption, though in a 
less severe form. | 

This locality (4) introduces us to a crush-conglomerate in 
‘Ordovician beds, and hence fixes the age of the movement as post- 
Ordovician ; (11) shows us a deposit consisting partly of pebbles of 
earlier date, formed by denudation, and partly of pseudo-pebbles 
derived from neighbouring beds of contemporaneous age by 
rushing. Whence we may learn that the test of included frag- 
ments to determine the relative age of beds, largely used in un- 
ravelling Anglesey geology, must be very cautiously applied. 


(iii) The Cemaes District.—The largest and most typical 
development of the crush-breccias is exposed along the coast in the 
neighbourhood of Cemaes at Porth Wnol, on Wylfa Head, and along 
the shores of Cemaes Bay. Immediately south of this remarkable 
zone lie the green-and-purple slaty beds which occupy the greater 
part of the Northern District, and compose the crush-zone at 
Trwyn Pen-careg. As we strike across the green-and-purple beds 
northward, say from Porth y Pistyll towards Wylfa Head, they 
re seen to dip a little east of north at a low angle (10° to 20°), 
increasing to 40° at Porth y Gwartheg. Patches of brecciated 
rock, agreeing in character with the Trwyn Pen-careg breccia, are 
visible here and there. Contortions set in, whose axes agree in 
direction of dip with the bedding, and the bedding becomes 
irregular, so that thin, harder, and flaggy bands in them appear to 
die out if followed for a few inches or feet along the strike. 
On reaching Porth Wnol these beds still form the main mass of the 
exposures ; but in them lie pieces of the gritty beds of the series 
and great lumps of greenish glassy quartzite that weathers with a 
white crust ; a still larger mass near by forms one of the ‘ quartz- 
knobs’ of Prof. Blake. 

On this headland, and along the shores between Porth yr Ogof 
and Porth y Wylfa, the slaty rocks are thoroughly broken up, and 
contain many inclusions of grit and quartzite. A few limestone- 
masses are folded in among the strata. One of these, of which 
about 30 feet in length is seen, is of such irregular shape that, had 
it been, as has been suggested, ejected from a volcano, it would have 
broken into several pieces in falling. 

I may mention here that limestone-‘ pebbles’ in these rocks 
are not common, and such few as are seen generally occur in the 
neighbourhood of these limestone-masses. 

The great majority of the inclusions are clearly identical with the 
grits that occur in thin bands to the south, and in thicker beds 


Nl) AA 
—_ i y 


y oe 


3 a 


— ene ZC : 
SE 


“ey MM ppad gy jo8o 1h yO ‘osnoyy eTA MA 


(ydvuabopoyd v wou unig) 
"ayuauiopbu0d-ysnio ay) we wounoyrznugs fo soyat bumoys ‘sanwag wwau ‘ulywuag uo aonf- 


Pol 


e 


or 


“SLT 


Vol. 55.] THE GEOLOGY OF NORTHERN ANGLESEY. 663 


around Cemlyn Bay. The matrix is also comparable with the fine- 
grained beds of the same series. I consider that the strata are, in the 
main, the upper beds of the Green-and-Purple Series, the grit-bands 
of which have been so much broken up that the fragments lie piece- 
meal in the shaly matrix, though contorted bedding can still be 
traced in places. As for the quartzites and limestones, some of the 
former are green, and graduate into the ordinary green grits, and 
such may, therefore, be considered altered grits of the same series ; 
but others, and the limestones, are in all probability parts of beds 
occurring higher in the succession, which have been folded in and 
erushed among the older disrupted strata. 

As we pass along the shore, between Porth yr Ogof and Porth y 
Wylfa, the crush-conglomerates still resemble the Cemlyn beds, and 
the grit-bands can be traced here in places, though generally they 
are completely disrupted. At the south-eastern corner of Porth y 
Wylfa, the greyish-green slates and flaggy grits of Porth y Pistyll and 
Porth y Gwartheg reappear. Some of the grits are broken to 
crush-breccias, but the fragments are angular and little displaced. 
To the north authiclasts again appear in the rocks, and this pseudo- 
pebbly character obtains along the coast all the way to Cemaes. I 
have not noticed any of the felsite-fragments which have been 
stated to occur both here and on Mynydd Wylfa. On Trwyn y 
Penrhyn (near Cemaes village) the rocky coast exhibits, among the 
broken-up grits and slates, masses of quartzite and limestone, some 
over 300 feet long, which follow the general strike of the beds. 
The limestones are clearly identical with those that occur on the 
eastern side of Cemaes Bay, where they are more fully exposed. 
Some of the calcareous shales belonging to them are also disrupted. 
I give a section (fig. 9, p. 660) along this part of the crush-zone which 
shows that in general structure the crushed rocks consist of a series 
of overfolds. This section (taken obliquely to the strike of the beds) 
gives only a generalized suggestion of what has taken place; the 
folding is in reality very much more complex, and is complicated by 
numerous thrusts and faults. In one spot, opposite the house 
known as Bay View, where the flaggy beds which constitute the 
bulk of the crush-conglomerate have been less disrupted than usual, 
the folding is still evident (fig. 10, p. 662). 

The eastern shore of Cemaes Bay yields further exposures of 
crush-conglomerate. Near the rifle-range is seen bedded limestone, 
passing down into glossy blue-black and greenish shale and beds 
of quartz-grit and quartzite. The bedding is very irregular; 
the bands of grit and quartzite are squeezed out among the shales 
into a succession of somewhat lenticular or rounded pieces, and 
all gradations from long bands to isolated fragments and lumps 
may be noticed. Fig.11(p. 664)gives an example of two such bands 
from this locality. These irregular crumpled beds of grit, quartzite, 
limestone, and shale are to be seen as far as the target which 
is fixed upon a headland (Pig y Barcud) of highly-contorted lime- 
stone and laminated limestone-shale. Occupying a broken and 
‘overfolded anticline between this limestone-headland and the large 
limestone-quarry of Trwyn y Parc isa strip some 100 yards wide 


664 MR. C. A. MATLEY ON THE [Aug. 1899, 


of typical crush-conglomerate, which consists of a dull slaty matrix 
full of grit-bands more or less broken into fragments. Some of tie 
bands can be followed unbroken along the strike for quite 8 feet, 
but they are mostly broken up into isolated pieces, the majority of 
smallsize. I measured some, however, having the following dimen- 
sions :—d3 by 3 feet; 65 by 2 feet; 6 by 23 feet. These larger 
inclusions were more or less lenticular in outline, and had the 
longest axis in the direction of the line of strike. They showed 
very little alteration; but the matrix of this crush-zone displays 
the typical micro-structures of crush-rocks, corresponding in all 
essential respects with the Isle of Man examples. 

The main limestone-mass,—that of Trwyn y Parc, in which the 
basin-like-folds noticed earlier in this paper (p. 652) occur—is now 
reached. It forms a band some 250 yards broad, beyond which is 
another tract of rocks similar to those on Cemaes shore. Though the 
beds are still broken up, the cataclastic derivation of the quartzite- 
lumps may be clearly inferred from their frequent occurrence as 
series of more or less connected lenticles. 


Fig. 11.—South-eastern corner of Cemaes Bay: parts of broken 
guartzite-bands. 


[The upper band is 33 feet, the lower 44 feet, in length. ] 


Continuing from this point along the shore of Porth Padrig, we 
come upon a large development of bedded grit and quartzite inter- 
stratified with pale yellow and sage-green, felspathic, shaly, and gritty 
mudstones, an occasional patch of limestone, and some Llandeilo 
black graptolitic shales. The thickness of individual beds is often ex- 
tremely irregular, and the whole of this section has evidently under- 
gone much movement. At Llanbadrig there is another development 
of limestone and quartzite among grey and reddish slaty beds. The 
harder rocks are very much crumpled up among the softer ones, and 
pieces of quartzite and limestone have become detached and lie 
isolated in the slates. ‘The structure appears to be somewhat similar 
to that noticed at Penrhyn, though the disruption is not so complete. 
Many of the bands can be readily traced, others are very irregular, 
and we find all stages from strings of lenticles to ‘pebbles.’ The 

uartzite-masses are much brecciated: some even seem to be made 
up of cemented fragments. 


Vol. 55.] GEOLOGY OF NORTHERN ANGLESEY. 665 


At the same time the explanation of the presence of the included 
fragments as due to ‘crush’ must not be pressed too far, for there 
are some inclusions, especially near Llanbadrig Point, which appear 
to be real pebbles ; and it seems that some pebbly slates have also 
been involved in the crush-movement and contributed their contents 
to the disrupted rocks. In some places irregular beds occur which 
simulate the crush-conglomerates, but appear to be mainly the 
result of crushing on pebbly slates. The true pebbles may be 
almost as much deformed and broken by movement as interbedded 
erit-bands. In one of these tracts of doubtful origin, north-east of 
‘Ogof Gynfor, all doubt as to the ordinary clastic nature of some of 
the inclusions was removed by finding in the rock a band of 
conglomerate which ran for quite 20 feet without a break, and by 
tracing patches of the same or a similar band in other parts of the 
exposure. It is, however, no easy matter in some cases, especialiy 
inland, where exposures are not continuous, to distinguish breccias 
originally clastic from those only secondarily so: that is, between 
crushed breccias and crush-breccias; and I have had to suspend 
judgment as to the real nature of some strata. The existence of 
‘one area of crush-conglomerate inland is, however, confirmed by 
microscopic evidence (N.A. 62). It lies south-west of Rhyd-y- 
clafdy, a farm east of Cemaes and north of the Amlwch Road, and 
similar rocks are seen at intervals between this locality and Porth 
Padrig. 

From Ogof Gynfor to Porth Wen the rocks show abundant 
evidence of great movement and disturbance. Around Porth Wen 
the disturbance is more pronounced, and the harder masses tend to 
break up and become surrounded by the softer. In the southern 
corner of Porth Wen Bay we again have rocks which may be called 
erush-conglomerates. As at Penrhyn and Llanbadrig, they he 
among masses of limestone and quartzite, and they look like 
disrupted beds of the Cemlyn grits and slates. East of Amlwch 
again, the folds of the highly-contorted Llaneilian rocks are some- 
times so broken that the harder grit-bands are shattered and 
‘discontinuous ; but the disruption is rarely complete. 


(iv) Western part of the north coast.—The ragged aspect 
of the rocks which characterizes the crush-conglomerate coast- 
‘scenery around Cemaes and Wylfa reappears between Hen Borth 
and Carmel Head, and becomes more conspicuous as we pass west- 
ward. It has already been seen that Carmel Head.is an area of 
powerful thrust-faults, and we may well expect to find crush- 
breccias here. The green beds depicted in fig. 1 (p. 645) have 
this brecciated character. At the extreme west, on Carmel Head 
itself, a strip of the Cemaes limestone is folded in with the crush- 
conglomerate, and fragments of it may be found as authiclasts 
farther east. 


It may be inferred from the foregoing evidence that the north 
coast of Anglesey from end to end has been intensely crushed. 
Along those portions of the coast where the rocks are fairly homo- 


666 MR. C. A. MATLEY ON THE [ Aug. 1899, 


geneous—whether they be soft and slaty, as between Bull Bay 
and Porth Wen, or whether they be hard and resistant, like the 
conglomerates and grits of Llanlliana headland and Torllwyn— 
there is no marked disruption; but whenever there are rapid alter- 
nations of the soft and hard types, then disruption becomes more: 
or less pronounced, and on the horizons of such deposits come in 
extensive zones of crush-breccias and crush-conglomerates. 


(v) Dykes in the crush-zones.—A number of subparallel 
basaltic dykes cut through the crush-conglomerates at Penrhyn, 
Llanbadrig, Porth Wnol, and Trwyn Pen-careg. They agree, on 
the whole, in direction with the strike of the crushed beds, and are 
clearly of later age than the movement; for they keep a straight 
course through the crush-conglomerate, and pass through it and the 
associated great limestone-masses uninterruptedly. 

There are, however, traces of dykes which, being of earlier date 
than the movement, have suffered equally with the rocks into 
which they were intruded. I have found the relics of two of 
these early intrusions. A few blocks of one of them lie in the 
slaty crushed matrix at Trwyn y Pare. The other is to be found 
east of the ‘ quartz-knob’ of Llanbadrig Point. It lies mainly 
in two lenticles surrounded by a broken quartzite-band and 
some slaty beds, but other lenticles and pieces of it lie near, folded 
and faulted among the other rocks. Not only have these dykes 
been torn to pieces, but their internal nature and arrangement have 
been altered. Almost all the structures and minerals have been 
obliterated by the movement, and their original composition and 
texture can now only with difficulty be recognized. Prof. Watts 
states respecting them (N.A. 10, Trwyn y Parc; N.A. 11 & 65, 
Llanbadrig) :—‘ Originally they appear to have been porphyritic 
basalts with a fine-grained groundmass. Their minerals are now 
largely calcified, the ilmenite converted into leucoxene, and the 
porphyritic crystals are mere ghosts, smashed, filled up with 
chlorite, and converted into aggregates of mica-flakes.’ 


(vi) Method of formation.—The causes ieading to the 
production of crush-conglomerates have been already discussed 
by Mr. Lamplugh in connexion with the Isle of Man examples, and 
Anglesey serves to confirm his conclusion that they are mainly due 
to the differential yielding of rocks when greatly compressed. The 
Porth Newydd sketch (fig..7, p.656) shows thatshale has been capable 
of accommodating itself to the squeezing by flowing round the harder 
masses; but the grit-bands, although yielding and stretching to 
some extent, have commenced to break, and the deficiency in exten- 
sibility has been made up by the broken pieces moving away from 
each other. The same effect has been produced, in the neighbour- 
hood of this section, in the black shale itself; for we find tougher 
black shale forming lenticles and discontinuous layers in the softer 
shale. Porth Newydd, too, shows that disruption can go on un- 
accompanied by folding ; but folding has, without doubt, largely aided 
the dismemberment of these rocks. Especially destructive to the 


Vol. 55.] GEOLOGY OF NORTHERN ANGLESEY. 667 


integrity of the strata would be the results of two systems of 
movement acting somewhat obliquely to each other, and this may 
have been the case in Northern Anglesey. Jointing, cleavage, and 
bedding would all be of service in producing a cataclastic structure. 


(g) Age of the Movements. 


The thrusting of older beds over the Ordovician rocks and the 
disruption of the Ordovician in Porth Newydd and Porth y Corwgl 
determine the age of the last period of great movement in 
Northern Anglesey as post-Ordovician. This movement is 
older than the dykes that cut through the crush-conglomerates, but 
we are not sure whether they are of Carboniferous or of Tertiary 
age. The Carboniferous rocks of Anglesey being, however, compara- 
tively undisturbed, as also seem to be the underlying deposits mapped 
as Old Red Sandstone, the period of the movement must lie between 
Upper Ordovician and Upper Old Red times. This movement may 
well have been contemporaneous with that of post-Cambrian and pre- 
Carboniferous date which produced disruption in the Manx slates.’ 

The recognizable Ordovician rocks have a less altered and, as a 
rule, a less disturbed look than most of the older deposits, and the 
Ordovician conglomerates give evidence that the older rocks had 
undergone considerable alteration, movement, and upheaval before 
Llandeilo times. 


VY. Tue Norruern CompLex AND 1Ts RELATION TO THE ORDOVICIAN. 


We now return to a consideration of the highly-complicated area 
spoken of as the Northern Complex. Apart from Ramsay’s 
description,” the only account which gives any detail of this area 
appears to be that of Prof. Blake under the head of ‘ The Disturbed 
Volcanic Group.’* We have seen that the ‘agglomerates’ of the 
latter writer’s description are crush-conglomerates, and that they 
are, in the main, disrupted portions of his ‘ Sedimentary Series ” 
(Green Series). The limestones, or at least some of them, he con- 
sidered to be the result of ‘ the action of calcareous springs,’ * while 
the ‘ quartz-knobs’ he looked upon as the product of ‘ pre-Cambrian 
geysers.” This group abounds in other lithological types, andin the 
complex lie the conglomerates, sandstones, and shales whose age is 
proved by the fossils recorded above (p. 640) to be Llandeilo. 
Ramsay ° believed that rocks of two systems, namely, Lower Silu- 
rian (Ordovician) and ‘altered Cambrian,’ occurred in this part 
of the district, but he found it impossible to determine how much 
of the strata belonged to each system, though he was inclined 
to consider the Cemaes limestones and all their associated rocks as 


1 Lamplugh, ‘ Crush-conglomerates of I. of Man,’ Quart. Journ. Geol. 
Soe. vol. li (1895) p. 584. 

2 Mem. Geol. Surv. ‘ Geol. N. Wales,’ 2nd ed. (1881) p. 240. 

3 Quart. Journ. Geol. Soc. vol. xliv (1888) p. 517. 

* Ibid. p. 519. 5 [hid. pn. 476. 

5 Op. supra cit. p. 242. 


668 MR. C, A. MATLEY ON THE [Aug. 1899, 


Ordovician. Some writers, as we have seen, have found a way out of 
the difficulty by lumping all the rocks together as Bala. Prof. Blake 
first definitely placed in the Ordovician the basal conglomerates and 
overlying strata of Ogof Gynfor and Porth Llanlliana. 

The prosecution of detailed field-work has not yet revealed a full 
or satisfactory sequence of the rocks in this area, though I am still 
hopeful of succeeding in this task. Nevertheless, some remarks 
on two of the principal rock-types and their relationship to the 
Ordovician may be of interest. 


(a) Limestones. 


The limestones of the district are of two main types. One is a 
fairly pure, blue limestone, effervescing freely with acid, and is the 
only kind that is quarried for lime. Its largest exposures are at 
Trwyn y Pare near Cemaes, and in the quarries near Llanlliana 
Farm ; but it also occurs at Penrhyn, at Pig y Barcud, between 
Llanbadrig and Cae-Owen, at the southern end of Porth Wen Bay, at 
Carmel Head, and in patches at other places. It is sometimes a 
laminated limestone with filmy black carbonaceous partings, but 
often so crushed that the partings are almost obliterated and the 
rock welded into a solid mass. 

The other type weathers characteristically as a light grey 
rock, but is brown or dark bluish and often gritty internally. 
Though it sometimes effervesces readily with acid, it is usually 
impure, dolomitic, or siliceous. It is often found with the blue 
limestone, and the two types appear to pass one into the other. It 
sometimes weathers to a ferruginous-brown colour. Between Ogof 
Gynfor and Porth Llanlliana there are strips of this impure lime- 
stone running from the coast inland; it occurs again on the south- 
east side of Porth Wen Bay, in Porth Padrig, on Penrhyn, and at 
various other localities. I have had none of the limestones analysed, 
but was told that the analysis of a rock from Porth Gynfor (Hell’s 
Mouth) showed it to be highly magnesian, as it yielded 61°15 per 
cent. of carbonate of magnesia and only 21:40 per cent. of carbonate 
of lime. This result, if trustworthy, could have been obtained, 
I think, only from a quite exceptional piece of rock, the magnesia- 
percentage being considerably higher than in pure dolomite. 

When the limestone retains its lamination the rock-structure is 
traceable, and it is generally found to be highly crumpled, some- 
times also to be imperfectly cleaved, so as to approach an imperfect 
limestone-slate. Black shales sometimes occur with the limestone 
and also reveal the bedding, as at Llanlliana Farm quarries, where 
the dip is seen to be almost vertical. The obliteration of bedding 
in the Trwyn y Pare quarry has been already noticed (p. 664), and 
it is most obscure in the solid limestone of other exposures. Much 
of it seems to be a cataclastic rock recemented by calcite and dolo- 
mite or sometimes by quartz-veins. 

It was interesting to find 12 yards of limestone in a ‘level’ 
driven into Mynydd-y-Garn near Ty’n-y-maen Chapel. This lime- 
stone has no outcrop. 


Vol: 55-] GEOLOGY OF NORTHERN ANGLESEY. 669 


Prof. Blake has shown that part of the Llanbadrig limestone is 
oolitic,» with compound grains: that is to say, two or three grains 
are often enclosed within a larger grain. From this structure, as 
well as from its intrusive appearance in the mass, he deduces that 
it is of later date than the rocks among which it occurs and that it 
was formed by the action of calcareous springs. I did not find an 
example of this structure at Llanbadrig, though I do not doubt its 
occurrence there ; but there is a band of light-brown limestone on 
the shore of Cemaes Bay, along the course of the rifle-range, which 
displays similar structures, except that the oolitic grains are not 
compound. This oolitic structure shows some breaking-down by 
veining, recrystallization, and a certain amount of dolomitization 
(N.A. 87), and may once have been a more common feature of 
these rocks.?. The nuclei show no trace of organisms. 

No fossils have yet been discovered in the limestones, though 
there are some structures in a microscope-slide (N.A. 12) from the 
Llanbadrig limestone which may possibly be organic. The general 
absence of fossils fits in with Prof. Blake’s chemical theory, but if 
we consider the reconstruction that these rocks have undergone by 
shattering, crystallization, veining, dolomitization, etc., we should 
expect very few organic remains that the limestones may have once 
contained to escape destruction. The crush-conglomerate explana- 
tion of the ‘ agglomerates’ of the north coast should clear away the 
difficulty experienced by Prof. Blake in accepting the limestones as 
ordinary bedded rocks. Their irregular, and sometimes even intrusive, 
appearance is an effect due to these hard resistant masses having 
been broken and crushed in by complicated movements among 
thinner strata. 


(6) Quartzites and ‘ Quartz-Knobs.’ 


The bands and pieces of quartzite which have been mentioned 
in connexion with the crush-conglomerates are for the most part 
evidently altered grits and sandstones. There are, however, both 
in and away from the crush-zones, thicker masses of quartz-rock of 
which Prof. Blake speaks as presenting ‘the most remarkable features. 
of allthe Anglesey rocks.’* He refuses to apply to these the name of 
quartzite, styling them ‘ quartz-knobs,’ and suggests that they have 
been produced by hot siliceous springs which may or may not have 
reached the surface. He distinguishes them by their purity of com-- 
position, their internal structure, obscurity of bedding, and form of 
outcrop, their characteristic mode of occurrence being as isolated. 
hummocks which vary in size from a low mound to a good-sized hill. 
In composition they are certainly of remarkable purity ; for instance, 
it was stated to me that the Craig Wen rock had yielded on analysis 


1 Quart. Journ. Geol. Soc. vol. xliv (1888) p. 518; ‘Microsc. Struct. of | 
Older Rocks of Anglesey,’ Brit. Assoc. Rep. 1888 (Bath) p. 589. 

2 It may be remarked that oolitic limestones are known in the Dalradian of | 
Scotland ; see A. Geikie, ‘ Text-Book of Geol.’ 3rd ed. (1893) p. 150, footnote. 

3 Quart. Journ. Geol. Soc. vol. xliv (1888) p. 475. See also Brit. Assoc.. 
Rep. 1888 (Bath) pp. 390-392. 


670 MR. C. A. MATLEY ON THE [Aug. 1899, 


99:6 per cent. of silica; but purity is not a sine quad non of a quartz- 
knob, for Prof. Blake includes among them, on account of their 
peculiar stratigraphy, some which ‘ might well pass for grits.’ 

Leaving Prof. Watts to deal with their microscopic structures, 
we may notice the manner of occurrence of some of these rocks in 
the field. The mass at Llanbadrig Point has already been dealt 
with (p.653 & fig. 5). It is cut up by thrust-planes, parts of it are 
well bedded, and it contains abundance of clastic grains. Another 
quartzite-mass is shown in the Ogof Gynfor section (fig. 3, p. 648), 
This latter is continued inland, by way of Penterfyn, as a bold, 
sometimes interrupted ridge, with a branch to Is-allt. Another 
ridge, overlain by Ordovician conglomerate, occurs between Ogof 
Gynfor and Porth Llanlliana. 

Prof. Blake figures another quartz-knob at Porth Llanlliana,} but 
its structure is not so simple as a general view leads one to suppose. 
At the base of the cliff itis a bedded and markedly clastic quartzite, 
the bedding being almost flat. It is separated from the more 
inclined mass above by a nearly horizontal plane which I take to be 
a shear-plane, as along it may be found some pieves of impure 
limestone and crushed shale. This plane is continued as a steep 
upward curve, and we find a mass of impure limestone forming a 
kind of sharp anticline in the heart of the knob. Climbing the 
steep slope to investigate it from the top of the cliff, we find that 
the quartzite is not a typical ‘ knob,’ but a reef or ridge along which 
are a number of small disused quarries. The rock is clearly a 
quartzite with abundant clastic grains, and it is overlain by a purple 
conglomerate. 

The quartzite-ridge crops out again at Hell’s Mouth and can be 
followed with the overlying purple conglomerate almost uninter- 
ruptedly to Craig Wen, ‘ the greatest quartz-knob of the district,’ ? 
which is being rapidly removed to make silica-brick. Here the 
outcrop widens. The north side of this hill gives the impression of 
a set of thick beds dipping steadily enough, though with a slight 
undulation, below the conglomerate; but the bedding-planes are 
full of slickensided surfaces. Along the road on the west side are 
faint indications of what seem to be southward-tilted anticlines, and 
small patches and pockets of a pale, highly-crushed, quartzose shale 
lie in the quartzite. A quarry driven into the eastern side of the 
hill, in the general direction of the strike, shows that a thick shale is 
included in the quartzite, and moreover that the rock has undergone 
such movement that the shale forms a tortuous band around masses 
of quartzite and has been so crushed in places as to be mylonitic. 
The north side of this quarry is represented in fig. 12 (p. 671). 
Purple and green are the prevailing colours of the shale. 

Descending into Porth Wen, we find the beds to be much disturbed. 
By the pier is a conspicuous detached rock of the same quartzite 
containing some thin crushed shale, and overlain by the same purple 
conglomerate. The broken and confused rocks south of the pier 
seem to be a continuation of the Craig Wen mass, and Prof. Blake 


? Quart. Journ. Geol. Soc. vol. xliv (1888) p. 520, fig. 22. 
2 Ibid. p. 521. 


Vol. 55.] GEOLOGY OF NORTHERN ANGLESEY. 671 


regards the confusion and irregularity as an appearance caused by 
*the underground branchings of the quartz-knob.’* Considering 
that all the other rocks in the Bay are shattered and displaced, we 
may safely assign this effect to disturbance. Its difference from 
the ordinary crush-conglomerates consists mainly in this, that the 
latter aré derived from soft rocks with subordinate hard layers, 
while here the predominating rocks are hard, with only subordinate 
soft layers. 


Fig, 12.— Quarry on the east side of Craig Wen, looking north: the 
section coincides approwimately with the strike of the beds. 


[The line-shading denotes the shales, crushed into the quartzite, which is 
indicated by small crosses. | 


We see, then, that the ‘quartz-knobs’ of Porth Llanlliana and 
Craig Wen are long ridges of a pure quartzite, which is built up— 
in part, at any rate—of clastic elements, shows bedding, contains 
bands of shale, and exhibits evidence of crushing and movement by 
which it has (to some extent) been broken up. Further movement 
might divide such ridges into a series of detached lenticles or ‘ knobs.’ 
This is what I consider has taken place between Porth Wen and 
Bull Bay, and in other parts ot this northern area where quartz- 
rock and limestone form strips or occur as lenticular, elliptical, or 
rounded masses along a zone which has a rough agreement with 
the general strike. A series of small ‘knobs’ of limestone and 
quartzite is exposed south of Bull Bay village. The farmer who 
worked the land told me that one of the quartzite-knobs had been 
entirely removed for road-metal, that it ‘did not run deep,’ but 
was surrounded everywhere by the country-rock. This statement 
strengthens the opinion that these masses are mere lenticles along 
lines of movement, and is confirmatory of the explanation that 
Mr. Greenly ? has given of the ‘ quartz-knobs’ of Pen y pare, near 
Beaumaris. 

Microscopic sections from the crush-zones reveal all the successive 


1 Quart. Journ. Geol. Soc. vol. xliv (1888) p. 521. 
2 ‘ Quartzite-Lenticles in Schists of S.H. Anglesey,’ Geol. Mag. 1896, p. 551. 


672 MR. C. A. MATLEY ON THE [Aug. 1899,. 


stages in the breaking-up of minute grit-bands to form tiny ‘ pebbles.’ 
We can pass from the microscopic slide to the hand-specimen, from 
the hand-specimen to the coast-exposure or quarry, and see the 
same stages of disruption of the harder rocks among the softer, on 
an ever-increasing scale. We have even gone farther and found 
that the isolated quartz-knobs and the detached limestene-masses 
are separated portions of great rock-sheets, and it is a matter of 
definition rather than a question of principle whether they should. 
be called the ‘ pebbles ’ of a great crush-conglomerate. 


(c) The Ordovician Rocks. 


Prof. Blake first recognized the Ordovician age of the Ogof 
Gynfor conglomerates ; the fossils recorded on p. 640 confirm his 
identification and fix the age as Llandeilo. These pass up, as 
shown in the section (fig. 3, p. 648), into black shales, which are: 
so quartzose as almost to merit the name of grits; their upward 
continuation seems to be the Dicranograptus-shales of Penterfyn, 
exposed inland, which contain some flaggy bands of oolitice iron- 
stone. The presence of Ordovician ironstones in Anglesey has, ipso 
facto, been considered to suggest an Arenig horizon,! but the 
Penterfyn ironstone is distinctly Llandeilo. The boundaries of this 
Ordovician tract are the two main faults shown in fig. 3, p. 648, 
which give a gradually widening outcrop till the series is cut off by 
an east-and-west fault from Porth Padrig; but these faults enclose 
much quartzite as well as Ordovician beds. Another tract, of a 
V-shape, mainly of conglomerates and grits, lies between this area 
and Porth Llanlliana. Its structure is obscured by cleavage, but 
the beds appear to be much folded and faulted, as the accompanying 
sketch (fig. 13, p. 673) indicates. 

We pass’ now to the noble headland of Llanlliana or Dinas Cynfor,. 
whose fine cliffs are mostly composed of Ordovician conglomerates. 
The uppermost beds are black-banded, grey, quartzose shales, 
cleaved into rude slates, and we recognize their equivalence with 
the darker gritty shale which occupies a similar position at Ogof 
Gynfor. South of these conglomerates and slates is the reddish- 
purple conglomerate that lies on the quartzite. This is so cut off 
from the other conglomerates that it is a question whether it should 
be included in the Ordovician; Blake was doubtful whether it should, 
and its colour is characteristic of the old rocks. But it seems to be 
partly derived from the underlying quartzite, its colour is sometimes 
leached out and then it closely resembles the other conglomerates, 
and fig. 13 has shown us that the undoubted Ordovician conglo- 
merates contain purple zones. We may, therefore, for the present 
regard it as the basal bed of the Ordovician, and we can follow it 
from Hell’s Mouth to Porth Wen still lying on the quartzite. The 
folded and cleaved conglomerates and grits, which lie between the 
purple rock and the sea, and form the headland of Torllwyn now 


1 Quart. Journ. Geol. Soe. vol. xxxviii (1882) p. 21. 


Mol. 55. GEOLOGY OF NORTHERN ANGLESEY. 673 


fall into place as Ordovician, and we have no difficulty with the 
Orihis Baalyana-beds which are part of this series, though perhaps 
faulted against the conglomerate. 

The remaining Ordovician outcrops are not extensive. To the 
east, between Porth Wen and Bull Bay, is a narrow’ strip, about 
z mile long, of conglomerate forming the ridge of Mynydd Pant-y- 
gaseg; near it, in Porth Pridd, are the black shales noticed by 
Prof. Blake. Finally, in Porth Padrig are the shattered black shales 
which have yielded Glenkiln graptolites; their horizon appears to 
be near that of the Penterfyn beds.! They strike inland a short 
distance, but are soon faulted out. It will be perhaps needful to 
add various small exposures of broken-up rocks to this summary of 
the Ordovician strata. 


bend 


OS) SNAP? 
a 


Fig. 13.—Purple band in cleaved grits and 
conglomerates, on the coast about 400 yards 
west of Porth Lianlliana. 


[The cleavage is not shown. ] 


This Ordovician sequence has a general correspondence with that 
established in Central Anglesey, where the series commences with 
conglomerates and passes up through grits and sandstones into 
black slates, in which ironstone is occasionally present. 


(d) Relation of the Northern Complex to the Ordovician. 


What, then, is the age of such strata in the Northern Complex 
as are not included in the Ordovician? Some of them, though 
shattered to ‘ crush-conglomerates,’ are clearly portions of the Green 
Series. The more typical members, like the limestones and the 
quartzites, come in between the Green Series and the Ordovician, 
and they may be in upward conformable sequence with the green 
strata. The Ogof Gynfor section shows that the limestone has 


' T brought away from the seaweed-covered rocks of Porth Padrig, near the 
black shales, a specimen of oolitic ironstone. It seems to be the equivalent of 
the Penterfyn ironstone, though my notes do not make it clear whether the 
specimen came from the black beds or from the neighbouring rocks. 


Q.J.G.8. No, 219, 2x 


674 MR. C. A. MATLEY ON THE [Aug. 1899, 


been brought up against the Llandeilo conglomerates by an over- 
thrust-fault. The limestone is therefore older, and there are occa- 
sional fragments probably derived from it in these neighbouring 
conglomerates. Also the conglomerates contain abundance of 
quartzite-pebbles, and lie on the quartzite, so that the quartzite is 
older than the conglomerate. 

The various lithological types of Northern Anglesey—the purple 
and paie boulder-conglomerates, the sporadic outcrops of limestone, 
the shales and flaggy beds of varied colours, the serpentines and other 
intrusions—have a remarkable resemblance, as Prof. Lapworth 
pointed out to me, to the general facies of the Girvan and Bal- 
lantrae rocks of Southern Scotland. Now the Lower Girvan rocks 
do correspond in age with the recognized Ordovician of Northern 
Anglesey, and, like the latter, their basal bed is a purple, red, or 
white conglomerate which lies on the Ballantrae rocks. The latter, 
once suggested to be pre-Cambrian, have proved to be no older than 
the Arenig. It therefore deserves consideration whether the two 
areas do not correspond in more respects than in lithological simi- 
larity, and whether we may not recognize in the Green Beds or in 
the Northern Complex, or in both sets of strata of Northern Anglesey, 
a series of rocks not very much older than the Llandeilo. We find, 
for instance, that black shales typical of the undoubted Ordovician 
are found among the pre-Llandeilo limestones, and that the purple 
colour which characterizes certain zones in the Green Series is not 
wanting in the Llandeilo conglomerates. On the other hand, the 
included fragments in these conglomerates prove that the Green Series 
and the quartzites had already undergone much alteration; moreover, 
the green rocks are correlated by geologists with the pre-Cambrian 
of other parts of Anglesey, and there is also the general argument 
(p. 643) that Northern Anglesey remained above water throughout 


Cambrian and Arenig times. Swayed by these conflicting con-- 


siderations, we are not in a position to assert unhesitatingly whether 
the Northern Anglesey rocks below the Llandeilo are of Arenig, 
Cambrian, or pre-Cambrian age. Though evidences appear to favour 
the opinion that these rocks, and more especially the Green Series, 
are very much older than the Ordovician conglomeratic base, it seems 
better to adopt a cautious attitude, and until the discovery of fossils, 
or pending the results of further work, to use, in speaking of their 
age, the general term pre-Llandeilo. 


VI. Summary. 


The principal conclusions arrived at in the foregoing pages may be 
summed up in the following statements :— 

(1) The barren green strata which form the floor of the greater 
part of Northern Anglesey are older than the Ordovician rocks to the 
south, and owe their apparently overlying position to a great over- 
thrust which sweeps in a curve from sea to sea. 

2) In the northernmost part of the island is a complex of rocks 
of varied lithological character. Among them occurs a group of 


> ee 


Vol. 55. | " GEOLOGY OF NORTHERN ANGLESEY. 675 


strata comprising conglomerates, grits, shales, and ironstone—all or 
most of which are of Llandeilo age. 

(3) The whole region has been extensively affected by powerful 
earth-movements, mainly acting from the north, which have con- 
torted, overfolded, dislocated, cleaved, crushed, shattered, and altered 
the strata. Thrust-planes of the Highland type occur, and the 
north coast exhibits extensive tracts of crush-conglomerates. 

(4) The isolated masses of limestone and quartzite that are to be 
found in the Northern Complex are portions of bedded strata which 
have been broken up by movement. 

(5) The green strata and the rocks of the Northern Complex are 
older than the Llandeilo, and were metamorphosed to their present 
extent before Upper Llandeilo times. Whether these rocks are pre- 
Cambrian, Cambrian, or even Arenig, Northern Anglesey as yet affords 
no direct proof, but the available evidence points strongly to the 
view that the bulk of the strata are of pre-Cambrian age. 

(6) The strata yield little evidence of contemporaneous volcanic 
activity. 


In conclusion I have to express my indebtedness to Prof. Lapworth 
and Miss E. M. R. Wood for their examination and determination of 
the graptolites, and to the former also for various suggestions; also 
to Mr. B. N. Peach for identifying and forwarding notes on the lime- 
stone fossils. Finally, my thanks are due to Prof. Watts for the 
trouble that he has taken in examining a large number of rock- 
sections aud contributing the following appendix. 


VII. Appenpix.—On the Microscopic Srupy of some of the Rocks of 
Nortnern Anetesey. By Prof. W. W. Warts, M.A., Sec.G.S. 


The following notes are based on the examination of about 100 
slides made from rocks collected by Mr. Matley during his work in 
Northern Anglesey, and examined by me at his request. These 
rocks may be classed under the following heads :— 


(1) The Green Series. 

(2) The Ordovician Rocks. 

(3) The Quartzites and ‘ Quartz-knobs.’ 

(4) The Results of Earth-movement ; Crush-Conglomerates. 


(1) The Green Series. 


These rocks usually show their original clastic structure dis- 
tinctly, although they are often considerably altered. They vary 
from coarse quartzose grits, through finer grits, to close-grained 
phyllites. The fragments consist of quartz-grains, clastic mica, and 
felspar, the first constituent being present in greatest quantity. 
Secondary chlorite and sericite are usually developed, the latter 
becoming more abundant as the evidences of earth-movement in- 
crease, and certain bands in the fine grits are schists consisting of 


676 PROF. W. W. WATTS ON THE MIcRoscoPrc stupy [Aug. 1899, 


little but sericite. More usually the groundmass is made up of 
fine chlorite-flakes embedded in granulitic quartz. Epidote in veins 
and isolated crystals is usually present. Secondary chalcedonic 
silica has often been deposited along planes and lenticles pro- 
duced by the movement. In the finer-grained rocks strain-slip is 
present, and not infrequently the rock is brecciated and contains 
fragments derived from itself; one example (N.A. 43, from the 
Craig Wen ‘ quartz-knob’) has the structure of a mylonite. One 
rock (N.A. 18, near Taldrws, Cemlyn) has been detected in the 
Green Series which contains, in addition to angular grains of quartz, 
several fragments of orthophyre, of angular grit, and crushed rock. 
Another rock (N.A. 70, Hell’s Mouth) in this series contains frag- 
ments, possibly of volcanic origin. The rock from Porth yr Ysgraff 
(N.A. 20), found in the neighbourhood of a dyke and of serpentine, 
exhibits dark spots, probably developed by contact-action subse- 
quently to foliation. A specimen of Llanfechell Grit (N.A. 86, 
Pen-y-bont) contains fragments of granulite, quartz-schists, micro- 
pegmatite, and felspar, all clearly derived from an area of foliated 
rocks. The bulk of the rocks may be spoken of as chloritic 
schists, chloritic and sericitic phyllites, and phyllitic 
grits. 


(2) The Ordovician Rocks. 


The rocks examined are mostly from the neighbourhood of the 
junction with the Green Series, collected with the view of obtaining 
evidence from the contained fragments, or else from the Ordovician 
beds in the Northern Complex. A typical specimen (N.A. 53, 
from Cefn-du-mawr, Llanfair-y’nghornwy) contains, among abun- 
dant angular fragments of quartz, granulated and non-granulated, 
the following larger fragments of rocks:—(qa) sericitic phyllites 
consisting mainly of granular quartz with little sericite; (6) well- 
foliated sericitic phyllites with minute quartz-grains; (c) sericitic 
phyllites with larger quartz-grains; (d) fine sericitic phyllites con- 
sisting almost solely of sericite; (¢) green quartz-chlorite-schists ; 
and (f) fine gritty rocks. All these types have been found among 
the rocks of the Green Series examined, and all are in precisely the 
same stage of metamorphism as in the fragments. Other examples 
of the rocks contain fragments of quartzose grits, quartzites, and 
rocks quite undistinguishable from those of the ‘ quartz-knobs.’ In 
one specimen there are abundant fragments of a limestone now 
crystalline. No volcanic fragments have been discovered in any of 
the specimens examined by me, with the exception of one doubtful 
instance from the western Porth Padrig. In a few cases, where 
there has been much movement, the groundmass of these rocks, 
and of the finer bands within them, becomes a sericitic schist. 
The state of metamorphism of the rock-fragments indicates that 
there must be a considerable gap between the Ordovician rocks 
and those of the Green Series. The rocks from Mynydd-y-Garn 
(N.A. 74 & 75) contain fragments of granitic, gneissic, and schistose 


ee 


Ee 


oe —— = 


Vol. 55.] OF SOME OF THE ROCKS OF NORTHERN ANGLESEY. 677 


rocks such as might have been derived from the area (N.A. 82, 83, 
& 84) near Pen Bryn-yr-Eglwys, 2 miles away, where granites, 
quartzose gneisses, and biotite-gneisses occur in situ. 


(3) The Quartzites and ‘ Quartz-knobs.’ 


Under the microscope I have not found it possible to draw any 
line between quartzites and the rocks of Prof. Blake’s ‘ quartz- 
knobs.’ Evidence of rounded quartz-grains can be generally ob- 
tained in both types of rock, but is not more easily obtainable in the 
one type than in the other. The amount of growth of secondary 
quartz on the grains is not very great, and it is difficult to identify 
because the old quartz is not much fuller of inclusions than the new, 
and at times the whole rock is traversed by abundant seams of bubbles 
which pass from one adjacent grain to another. Still,in most of the 
slides I have found this secondary growth, and when it is well 
developed the grains interlock in a way which shows that it is only to 
be expected that the clastic structure would not be always apparent. 
In all the slides there is a certain amount of interstitial quartz 
which takes several forms; it may be granulitic, microcrystalline 
and interpenetrating, cryptocrystalline, or minutely clastic. In 
some cases the adjacent well-rounded grains are coated with fringes 
of bright sericite (N.A. 31, from a ‘ quartz-knob’ at Llanbadrig Point 
[Trwyn y Buarth]).* The grains often exhibit strain, but not often 
granulitization. Grains of felspar and other minerals are decidedly 
rare, and the groundmass is usually purely siliceous, but in some 
cases it is full of sericite, which has a parallel and schistose arrange- 
ment. Two specimens were cut from a band of shale included in 
the ‘ quartz-knob’ of Craig Wen. One of them was a rather fine- 
grained quartzose grit, very much crushed, with its grains embedded 
in a groundmass of sericitic schist ; the other was a sericite-schist, so 
much crushed as to be brecciated and to have acquired the structure 
of a mylonite; lenticles of quartzite are crushed into it. 


(4) The Results of Earth-movement ; 
Crush-Conglomerates. 


Nearly all the rocks examined have suffered in some way from 
earth-movement. Hither they are cleaved, or they show strain-slip, 
or they are brecciated and phacoidal; and the amount of crushing 
may be roughly measured by the amount of sericite developed in 
the groundmass, as well as by the shearing, granulitization, and 
eventual fraying-out of the contained fragments of quartz. Most 
of the stages towards the formation of crush-breccias and crush- 
conglomerates can be traced in the slides as well as upon the 
ground, and the best examples are as marked and unmistakable 
as those discovered in the Isle of Man by Mr. Lamplugh. As a 


1 See Greenly, Trans. Edin. Geol. Soc. vol. vii (1897) p. 256. 


678 MR. C. A. MATLEY ON THE [Aug. 1899, 


rule the coarser rocks form fragments in the finer, but not infre- 
quently ‘pebbles’ (authiclasts) and matrix are made of the same 
material. Many of the larger fragments have undergone no 
mechanical deformation in their interior, but the smaller fragments 
are kneaded and crushed, and the isolated grains of quartz are granu- 
lated. Usually the fragments consist of a single type of rock, but 
often several distinct types occur together. In the example (N.A. 
63) from the west side of Porth y Wylfa various grits, sericitic and 
chloritic schists, etc., occur in a single rock-slide, as is the case with 
the thrust-conglomerates described by Gardiner & Reynolds from 
Portraine.’ Sometimes quartzites of the ‘ quartz-knob’ type occur 
in the conglomerates, but so far no fragments of volcanic rock have 
been found in them; indeed, in all the rocks examined there is 
very little volcanic material. Quartzite-bands found in the crush- 
conglomerates are much crushed. 


DIscussron. 


The Rev. J. F. Biaxe said that the first impression created on 
him by the paper just read was a sense of his own rashness eleven 
years ago in attempting to explain the whole of the Monian system 
in a single evening, whereas the Author that night had been unable 
to conclude his account of even a very small portion of the rocks. 
The second impression was one of satisfaction that an independent 
worker, who had been enabled to devote some time to the subject, 
practically confirmed all the speaker’s contentions (quartz-knobs 
excepted); which was all the more important, inasmuch as in the 
new Index-map of the Geological Survey all the Monian rocks of 
the district had been changed into Ordovician on the strength of 
some supposed intercalations of black shale, which the Author now 
rightly interpreted as a result of complex thrusting. He begged 
that the Author would modify the statement he had made that the 
speaker had claimed Orthis Bailyana as a Monian fossil. He had 
never come nearer to that than saying that he should like to do so ; 
but, after an examination of the Wexford beds tn situ and the col- 
lection in the hands of the Irish Geological Survey, he could find no 
encouragement for any such idea. He quite appreciated the statement 
of Prof. Watts that the northern so-called ‘ volcanic series’ did not 
contain any fragments of volcanic rocks, or very few, in the shape 
of lapilli; but the angular scattered fragments of felspars, ete. 
seemed to suggest some volcanic origin. He did not understand 
the Author’s section [fig. 9, p. 660], as the folds were indicated as 
having a north-and-south axis, whereas, the pressure being from the 
north, the axis must be east-and-west. 

With regard to the quartz-knobs, the best was seen near Parys 
Mountain. Not every quartzite in the district was a quartz-knob, 
and the rounded grains in many of the latter had been recognized 


1 Quart. Journ. Geol. Soe. vol. liii (187) p. 527. 


= 


Vol. 55. GEOLOGY OF NORTHERN ANGLESEY. 679 


by the speaker and accounted for. These were not the difficulty ; 
it was the stratigraphical one. If quartz-knobs were fragments of 
old sandstones separated by earth-movements, where were these 
sandstones, and what was the cause of the remarkable purity of the 
material? Some of these knobs were quite white, and perfectly 
_ isolated amidst miles of dark schistose slates, etc. 

Prof. Sottas joined in recognizing the importance of this con- 
tribution to our knowledge of an unusually difficult country. As 
regards the ‘ quartz-knobs’ he was in complete agreement with the 
Author; and having had, through the kindness of Prof. Blake, the 
opportunity of studying specimens from a typical quartz-knob of 
Anglesey, he had found in them the same characters as those that 
distinguished the quartzites of Howth and Bray, which had clearly 
originated from true sandstones. ‘The joints and other fissures of 
these masses were filled with secondary quartz, which had penetrated 
the adjacent portions of the rock and destroyed in many cases all 
traces of its original structure; but the great mass of the rock had 
escaped this influence, and afforded obvious evidence of a clastic 
origin. The isolation of the quartzite-masses stood in connexion 
with the earth-movements that had produced ‘ flow-breccia’; 
indeed, the whole terrane had been forced into a state of °‘ flow,’ 
and the ‘quartz-knobs’ were phacoids of quartzite on a grand scale. 
The quartzite and green-and-red slates of Howth and Bray would 
require but slight alteration to acquire characters like those of the 
Green Series of Anglesey. 

Dr. Hicks congratulated the Author on the careful manner in 
which he had worked out the geology of an important and difficult 
district in Anglesey. He believed that the interpretation put 
forward by him was essentially the correct one, and the one to be 
expected in an area where pre-Cambrian and Lower Paleozoic rocks 
had been so greatly affected by earth-movements. The Orthis 
exhibited seemed to him to be Orthis Carausii, which is found at 
St. David’s in beds of Tremadoc age. There are conglomerates in 
Anglesey belonging to different horizons—the oldest, he believed, 
are those near Llanfaelog, which contain not only fragments of 
green schists but also pebbles of gneiss and granite, and are over- 
lain by a series of greenish and grey sandstones older than the 
slates of Llandeilo and Arenig age. In so greatly faulted an area 
it is extremely difficult to make out the natural succession, for series 
of beds are frequently absent or not exposed, not from want of 
deposition, but as the result of faults and overthrusts. 

Prof. Warts said that microscopic examination had not enabled 
him to discern any difference between Prof. Blake’s ‘true quartz- 
knobs’ and others which that observer disclaimed as quartz-knobs. 
He had had the pleasure of working with Prof. Sollas in the 
Howth district, and eagerly awaited the publication of the latter’s 
map. The structure of some crush-conglomerates curiously simu- 
lates the geological map of that district—and this extraordinary 
resemblance extends to the hand-specimens of the rock, even to the 
very appearance of the quarries. There is no doubt that the origin 


680 THE GEOLOGY OF NORTHERN ANGLESEY. [Aug. 1899. 


of quartzite does still present considerable difficulties. He could not 
refrain from saying that the kindly spirit in which Prof. Blake had 
spoken of the present Author’s work deserved their warmest thanks. 

Prof. Larpworts also spoke. 

The AvtHor, in reply to Prof. Blake, stated that he had seen 
the latter’s ‘ best quartz-knob’ near Parys Mountain, but it was 
outside the area described. Several masses in Northern Anglesey 
specifically mentioned by Prof. Blake as ‘ quartz-knobs’ were dealt 
with in some detail in the paper, but time had not permitted the 
evidence to be given that evening. He thanked all the speakers, 
especially Dr. Hicks, for the very kind way in which they had 
received his paper. 


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CONTENTS, am 
= ; - | 


PAPERS READ. 
20. Prof. T. G, Bonney & the Rev. Edwin Hill on the Relations of the Chalk 


and Drift insMoen and Rigen ‘isc..: cts, as. Mek enee tetany tee 305 — 
21. Mr. J. B. Marr on Limestone-knolls in the Craven District of Youre and 
elsewhere. (Plate MALV.)" lecivaseis..nsss,0cresvas stain ttanseeys oat aien ae 327 
22. Mr. J. R. Dakyns on Limestone- knolls below Skipton and Grassington in 
CGHAVONT oi. cc ciane wen « vareiee nse Wn dwiie's os C8 os vec tp dee eae sapaeriee aaa ee ean a 
23. Dr. Wheelton Hind on Three new Species of British Carboniferous Lamelli- 
branchiata. °>(Plate SX V2) e.ca. il ease oc. causes saeeel eae pore 365 
24, Mr. C. T. Clough & Dr. W. Poilard on Spinel and Forsterite fa the” 2 
Glenela Limestone: 02%. 6.2: ene oo. stoeesas vteeceesrieeeednc cass ocece iret ene 7 
25. Mr. A. Vaughan Jennings on the Geology of the Davos District. (Plates 
XXVI & XXVIL. Ve PET gee des See F ak wis ws delve 34 20 24 nes Salsa oe SC 381 
26. Prof. H. G. Seeley on Hemiomus major, gen. et sp. nov., from Tonbridge: eines 413 
27. Prof. H. G. Seeley on Evidence of a Bird from the Wealden Beds of Ansty 
Tanie; "Cuckfield oc ag ese sNGiexgee ss -sstaees + pe detec sta: oes eon arena 4) 
28. Mr. E. T. Newton on the Vertebrate Fauna of the Ightham Fissure. (Plate 3 
KX VIL) ooo i riety feaduanees aes cagecsadees thentvonks ove useay es aaa a 419. 
29. Mr. John Parkinson on an Intrusion of Granite into Diabase at Sorel Point, 
Jersey, . (Plates XX EX GN) ak Movwkne swans tatte ress acct tee ae ee 430 
30. Messrs. J. Park & F. Rutley on the Rhyolites of the Hauraki Goldfields, New 
Zealand, | (Platés XX XIX V 1) oe chs: vcverchesesuecavsinat saree) tere 449 
31. Mr. J..B. Hill on Progressive Metamorphism of Dalradions Sediments inthe = © 
Loch Awe Region =:2. tigeeis:t<:s seuss puote. +s -cabes su ske ov chat ene sete ann 470° 
32. Dr. A. W. Rowe on the Genus Micraster, between the zones of Rh. Cuvieri ' 
and M. cor-anguinum. (Plates XXXV-XXXIX.) err 
33. Mr. W. Gibson and Dr. W. Hind on Agglomerates and Tuffs in the Carboni- 
ferous Limestone Series of Congleton Edge, with an Appendix on the Petro- 
graphy of the Rocks by Mr. H. H. Arnold-Bemrose .....:.....-.:sceceecaseeceeee 548 
34. Miss M. M. Ogilvie [Mrs. Gordon] on the Torsion-Structure of the Dolomites, 
(Plates. )e 55 ig 2h: scapes ade tec nu shoes sk gate eveear Devea eam ee ane 560 
35. Mr. C. A. Matley on the Geology of Northern Anglesey, with an Appendix on 


the Microscopic Study of some of the Rocks by Prof. W. W. Watts ......... 605 


(No. 220 will be published next November. | 


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Vol. 55. THE GLACIAL PHENOMENA OF SPITSBERGEN. 681 


36. AppitionaL Notes on the GuactaAL PHENOMENA of SPITSBERGEN. 
By E. J. Garwoop, Esq., M.A., F.G.S. (Read June 21st, 
1899.) 

[Pirates XLI-XLVIII.] 


I. InrRopvuctIion. 


In a paper published in the preceding volume of this Journal,’ 
an account was given of the glacial phenomena observed in Spits- 
bergen by Dr. Gregory and myself during our visit with Sir Martin 
Conway in 1896. The work accomplished that year was practically 
confined to observations made in the valleys lying to the east of 
Ice Fjord, namely Advent Vale and Sassendal, with their tributary 
glens and connecting passes. Over this district there is no approach 
to a continuous sheet of ice; our detailed investigations were 
therefore limited to an examination of the small glaciers occurring 
over restricted areas, or debouching into the larger lateral valleys, 
- from the icefields to the north. The time at our disposal that 
year did not admit of an expedition on to the inland ice, marked 
in the chart as occurring farther north, of which we caught glimpses 
on more than one occasion from the summits of the Sassendal peaks. 
From the views, however, which we obtained, this district promised 
to afford admirable material for the study of ice-action on a large 
scale. As no information could be procured regarding the character 
of the interior of the northern part of West Spitsbergen, save that 
the chart bore the mysterious legend ‘high inland ice,’ a term 
which we had found on previous occasions to be synonymous with 
‘unexplored,’ I decided to revisit the island, and was fortunate 
in persuading Sir Martin Conway to join me on an expedition 
during the summer of 1897 into the interior of the country lying 
north of Ice Fjord. 

The objects of the expedition also included the exploration of the 
mountain-ranges in the neighbourhood of Horn Sound, situated at 
the southern end of the island, from which I had been driven back 
by bad weather the previous year. 

The geographical results obtained have already been published.” 
The present communication records observations made on ice- 
action in the districts which we traversed during this expedition. 


Il. Tae Inzanp Icn. 


The tracts of ice which we visited are described as ‘high 
inland ice’ in the old chart of Spitsbergen, and occupy two distinct 
areas. The larger of these covers a tract of elevated ground lying 
between N. lat. 78° 30' & 79° 10’, and E. long. 16° & 20°. 


* Vol. liv (1898) p. 197. A full list of references to previous work on ice in 
Spitsbergen and kindred districts elsewhere will be found in the paper quoted. 
* Geogr. Journ. vol. xii (1898) p. 137, 


Q. J. G. S. No, 220. 2Y 


682 " MR, E. J. GARWOOD ON THE [Nov. 1899, 


The other tract lies immediately to the west of this, and occupies 
the greater part of King James’s Land; they are separated one 
from the other by Dickson Bay and Wijde Bay and by the depressed 
area which connects these inlets (see Map, Pl. XLI). 

The expression ‘inland ice’ is a vague geographical term, useful 
perhaps when applied generally to a country in which land-ice 
predominates, but which has been neither mapped in detail nor 
differentiated into separate glacier-systems. For strict accuracy, 
however, the terms ‘ ice-sheet’ and ‘ glacier’ convey a more definite 
meaning. Though I am not aware that an ice-sheet has ever 
been scientifically defined, most writers appear to use it in the 
sense of a complete covering of ice, radiating from a watershed 
consisting of snow and ice, and not confined or directed by visible 
barriers of rock, while a glacier, though it may originate in an 
ice-sheet, occupies a definifé valley. As thus defined, a small 
ice-sheet does exist on each:of- the above areas, the radiating- 
point and chief gathering-ground being situated somewhat north- 
west of the centres of each area, with supplementary radiating-points 
to the north and east. If we accept this view, the rock-ridge of Mount 
Chydenius, in the eastern tract, and the group of peaks including 
the Three Crowns protruding above the ice in the centre of King 
James's Land, may be regarded as groups of nunatakkr, though, in 
the latter ease, the system is extremely complicated (see panorama, 
Pl. XLIT). There can be no doubt, however, that, whether this appli- 
cation of the term ‘ice-sheet ’ is accepted or not, the effect produced 
is practically the same as that which would result from the presence 
of a much more extensive sheet. We have here a district from 
which the ice-cap, which once buried it more deeply, is gradually 
melting off: the melting has not, however, yet progressed sufficiently 
to have reached the Alpine-glacier stage, and we still have un- 
doubtedly the effects of an ice-sheet with its valley-bound ground- 
ice and freely moving surface-layers, with the result that the latter 
travel in an independent direction, frequently at right angles to 
the former. The district has, however, reached a stage in its history 
when the original central surface radiating-point has been replaced by 
several separate decentralized points by the lowering of the ice-surface 
and the obstruction offered by a constantly increasing number of 
nunatakkr.’ Here is in fact a condition of things almost identical 
with that which obtained in our own country, on the land-ice 
hypothesis, during the Glacial Epoch. As the cold conditions 
passed away and the ice-sheet covering Britain melted off, the 
radiating-point must have been replaced by decentralized points in a 
similar manner ; and this fact is perhaps not sufficiently borne in 
mind in accounting for such phenomena as the intercrossing of the 
erratics in many of our own glaciated districts. 


1 A careful examination of the nunatakkr met with during the expedition 
across these ice-sheets revealed nothing unexpected as regards their flora. 
The plants all belong to the more universally distributed species collected on 
the coast and in the ice-free valleys, such as Saxifraga oppositifolia, Papaver 
nudicaule, Dryas octopetala, etc. 


Vol. 55.] GLACIAL PHENOMENA OF SPITSBERGEN, 683 


IIT. Surrace-PHENOMENA OF THE ICE-SHEETS. 


Although in some respects the surfaces of these ice-sheets are 
not the best place to observe the action of ice, they are not without 
their points of interest. In the upper portion near the radiating- 
points the slope of the surface is gentle and snow-covered, becoming, 
however, wavy and undulating as it approaches a nunatak; in 
places also eddies may be observed, distinctly comparable with the 
swirl of river-water in the neighbourhood of submerged rocks, so 
that, even where no rock is visible above the ice, the presence of 
buried mountain-ridges mav be often inferred. In immediate 
proximity to a group of nunatakkr the ice is frequently much 
crevassed, especially towards the lee side of the obstruction, the 
fissures representing true marginal crevasses as the direct result of 
differential ice-movement. Glacial lakes are also of frequent 
occurrence here. On the impact-face’ of a nunatak the ice is 
much compressed and rises considerably above its average level 
(Pl. XLVI, fig. 2). This is undoubtedly due to the retardation of 
the lower layers, and the increased shear-friction produced in the 
upper ones: this surface-swelling therefore corresponds to the raised 
lip which surrounds the snouts of many of the glaciers of the 
country when advancing or when impeded by their old moraines, 
as previously described.” 

In connexion with this compression of the ice in the neighbour- 
hood of the nunatakkr, an interesting phenomenon is sometimes 
noticeable which does not appear to have been previously described. 

When any crevassed portion of the ice-sheet is thrust against 
such an obstruction, the pressure brought to bear causes the 
crevasses to close, and an interesting peculiarity in the constitution 
of the bridges that span the crevasses is forcibly brought to notice. 
These bridges, instead of consisting of snow as do those which 
occur in Swiss glaciers, are composed of solid ice, the result of 
continuous melting in the summer and the action of severe 
winter-frosts. When therefore the walls of the crevasse are 
reunited, the ice-bridge which spans it is squeezed upward into the 
form of an arch which finally becomes a complete tunnel: these 
may be seen not infrequently running in parallel sets for long 
distances (Pl. XLVI, fig. 1); being broken in places, water readily 
obtains access to them, and it is not an uncommon occurrence to 
find these tunnels being made use of as drainage-channels for the 
surface-water of the district. One of the most striking instances 
observed by us occurred where the drainage from the Devonian 
shales forming the flank of a nunatak coursed in a blood-red stream 
between the blue translucent walls of a tunnel of this description 


(Pl. XLY). 


1 There being no recognized English equivalent in general use for the st oss- 
seite of the German geologists, I have ventured to use for it the term im pact- 
face throughout this paper, since it commended itself to me as a fairly accurate 
and expressive substitute. 

2 Quart. Journ. Geol. Soc. vol. liv (1898) p. 208 & pl. Urs 

"2N2 


684. MR. E. J. GARWOOD ON THE [ Nov. 1 899, 


Another interesting point to be noticed in connexion with these 
nunatakkr is their effect on the englacial moraines brought 
down by the ice-sheet. In several cases where a nunatak pro- 
truded from the ice, the overriding of the upper layers and the 
heaping-up of the ice on the impact-face of a nunatak caused the 
moraine-material, interstratified in the lower layers of the ice, to be 
brought up and deposited on the surface in a manner similar to 
that recorded in connexion with the Greenland ice-sheet.! (See 
Pl. XLVI, fig. 2.) 

Attention is here called to this action, because it appears probable 
that the upward motion of this material is produced in identically 
the same way aS was shown to occur in the case of raised-beach 
material brought up by the advancing front of the Ivory Glacier in 
the paper previously cited,—the obstruction exerted on the lower 
layers of the glacier by the ice-talus in the one case being repre- 
sented in the other by the submerged portion of the nunatak. 

Under this category I was at first inclined to place the material 
which forms one of the most interesting medial moraines of 
Nordenskjold Glacier. It consists of a row of large rounded and 
polished blocks of hard Archean granites, many of which are 
4 to 6 feet in diameter. They could be seen stretching away up the 
glacier to its source in a large nunatak of Carboniferous rocks, which 
separates the main mass of the glacier descending from Mount 
Chydenius from the smaller glaciers to the south. These blocks 
were almost perfectly rounded, and occurred at intervals of many 
yards (Pl. XLVIII, fig. 2); they were entirely free from admixture 
of angular débris, and had undoubtedly travelled in or beneath the 
ice. They may have reached the surface by elevation against the 
nunatak as described above: unfortunately the thick weather 
which we encountered during the exploration of this ice-sheet 
prevented me from deciding this question; but, judging from a 
distant view which I afterwards obtained from the coast, I am — 
inclined to think that they originated in a different way. 

The blocks appear to belong to an earlier period of glaciation, when 
the ice-sheet covered much higher ground than at present, and had 
therefore a different radiating-point. During this period the blocks © 
must have been stranded on the surface of the nunatak as part 
of the ground-moraine of the ice-sheet, and strewn over the surface 
much as are the hyperite-boulders observed by me 1500 feet up on 
the plateau of the Sassendal. As the disintegration of the Carboni- 
ferous rocks takes place, these Archean blocks are hurled on to 
the glacier below, and travel down the ice parallel with the 
angular surface-moraine strewing the surface a little nearer to the 
side. We thus have a kind of fossil moraine again playing its 
part as a surface-moraine, at a distinctly subsequent period in the 
glacial history of the district. 


The observations made in the previous year upon the elevation of 


1 “Meddelelser om Greenland,’ pts. i-vi (1879-1883). 
* Quart. Journ. Geol. Soc. vol. liv (1898) p. 205. 


Vole 55. GLACIAL PHENOMENA OF SPITSBERGEN. 685 


loose material by the advancing front of the Ivory Glacier were 
borne out by phenomena of a similar character met with during 
this expedition. Wherever suitable material existed, it was in- 
variably picked up by the sole of the ice and sheared up gradually 
through layer after layer till thrown out on the surface of the ice. 
I would especially mention the débris so thrown out by the ice 
on the south side of King’s Glacier, and the englacial material 
brought up against the nunatakkr mentioned above. 


TY. DRAINAGE OF THE |cE-SHEETS. 


Where the ice-sheets are crevassed, as in the neighbourhood of 
nunatakkr, no surface-drainage really exists, but everywhere above 
the snow-line in summer, where the surface is unbroken, an 
enormous quantity of water is constantly set free. This accumulates 
to such an extent as to saturate the snow and form a spongy mass, 
into which the traveller frequently sinks even when supported on 
snow-shoes. This occasionally collects in some of the surface-eddies in 
the ice and forms lakes, especially in the hollows formed on the lee 
side of a nunatak. ‘The resulting drainage gathers into rills and 
water-channels, and eventually into voluminous streams which, in 
King James’s Land, have excavated channels several feet below the 
surface of the ice. These channels, with their treacherous banks, 
their slippery floors of hard blue ice, and their rushing torrents, 
occasionally form serious obstacles to the exploration of the ice- 
sheets. One of the interesting features to be noticed in connexion 
with these streams is the abundance of rock-fragments occasionally 
found in their channels; these are derived from morainic material, 
and during their passage downward become to some extent rounded 
and waterworn before being deposited lower down the valley. 

In addition to surface-streams, englacial streams are also met with, 
and it is in connexion with one of these latter that the most 
suggestive deposits of this character occurred. About a day’s march 
from the coast, on the left bank of King’s Glacier, we found a very 
interesting example of an englacial stream, which originated in a 
lake formed annually on the lee side of a large nunatak. During 
the winter months the entrance to the channel was evidently 
blocked by snow, so that the water, formed by melting snow in 
spring, accumulated between the edge of the ice and the hollow 
formed on the lee side of the nunatak. As the summer advanced 
the snow-barrier melted away, and the water of the lake escaped 
with great impetuosity down what may have originally been a 
flaw in the ice, but which, when we saw it, was a tunnel 
12 to 15 feet in diameter excavated in the solid ice. The direction 
of the tunnel ran at right angles to the direction of the valley and 
was plentifully strewn with moraine-material. This material was 
derived partly from angular fragments which constantly fell from 
the slopes of the nunatak, and partly from the englacial moraine 
dragged up to the surface by the pressure against the nunatak. 
The débris derived from both these sources had evidently been 


686 MR. E. J. GARWOOD ON THE [Nov. 1899, 


carried with great force along the tunnel during the bursting of the 
lake in the previous spring, and, when we saw it, still strewed the 
mouth and floor of the tunnel; the direction of this channel, as 
previously stated, was at right angles to the main lie of the valley, 
so that on the valley becoming free from ice, as the climate amelio- 
rated, this waterworn glacial material would be deposited as a 
gravelly ridge, running roughly at right angles to the long axis of 
the valley and forming a kame. (See Pl. XLVII, fig. 2.) 


V. Rate or Movement or tHe Icz. (Pl. XLIV.) 


During our short visit to the interior we were unable to under- 
take any measurements to ascertain the rate of movement of the 
ice-sheets. From what we saw of them, however, I am inclined to 
think that the motion is not nearly so great as that of the glaciers 
near the coast. The rate of advance of these latter glaciers was not 
accurately measured; but, judging from observations made before 
and after our journey into the interior, I do not think that this 
rate can average less than 15 or 20 feet in every 24 hours. I have 
endeavoured to check this estimate by observations made on 
the size of the icebergs daily calved from the front of King’s Bay 
Glacier. The bergs here do not appear to be produced by any 
strain on the ice due to a sudden fall in the ground along the edge 
of the coast, but are caused primarily by the action of the tides. 
As the tide rises, the upward pressure exerted by the water upon 
the submerged portion of the glacier-front forces off a narrow 
strip of ice which breaks up and floats away in the form of 
icebergs. The same phenomenon takes place during the fall of the 
tide, and, as the support of the water is withdrawn, another slice is 
removed. This discharge appears chiefly to occur immediately after 
half-tide ; in both cases the amount broken off will therefore 
represent half the portion of ice which has advanced in the in- 
terval between one complete rise and fall of the tide. Broadly 
speaking, then, four periods of discharge may be said to occur every 
24 hours. I endeavoured to estimate the width of the bergs collected 
in front of the glacier as we rowed through them on the evening 
after our return to the coast ; many of these could not have been 
less than 8 to 10 feet across in their shortest diameter. If, 
therefore, we suppose these to represent the width of ice broken 
off during one rise or fall of the tide, this would give 32 to 40 feet 
as the amount of advance in 24 hours; or even supposing that these 
larger bergs represent a portion of the ice-front which resisted one 
rise or fall of the tide, and which would represent the advance 
during half a day, it would give 16 to 20 feet for the daily 
motion of the glacier. In addition, however, to the larger bergs, 
splinters of ice were constantly falling throughout the day; and I 
do not think, therefore, that an estimate of 25 feet for the motion 
of this glacier during every 24 hours would be excessive. 


Wor s5.| GLACIAL PHENOMENA OF SPITSBERGEN. 687 


VI. Acrion oF SEA-ICE. 


The relative amount of action produced by the various forms of 
sea-ice is difficult to differentiate; scratches found on the surface of 
submerged rocks may be due to either icebergs or floe-ice, or to 
movements taking place in the continuous sheet of ice occupying a 
bay in winter. Beautiful examples of scratching and grooving are 
to be found on the surface of some of the submerged limestone-beds 
which lie south-west of Coal Haven in King’s Bay. 

Since these are covered by water, except at very low tide, their 
glaciation cannot be attributed to the action of land-ice. They 
form the base from which a spit of shore composed of pebbles and 
boulders projects into the fjord, at low tide enclosing a lagoon. 
This ridge is chiefly composed of blocks of rock dropped by icebergs 
which have stranded in the shallow water at the edge of the reef 
and partially melted before being carried out to sea. Itis therefore 
probable that the scratches, which here run parallel to the coast- 
line, are produced by these icebergs. Some, however, which I 
observed running at right angles to the coast, may have been 
produced by the pressure of the ice covering the bay in winter due 
to any sudden increase in the cold, when a direct thrust would 
take place on shore, the centre of the bay becoming the radiating- 
point, in a manner similar to that suggested by Mr. Lamplugh in the 
case of the ice-sheet that occupied the North Sea during the Glacial 
Period. 

As the country is known to have been rising for some time 
past, I am inclined to think that much of the rounding of the lower 
slopes surrounding the bay has been produced by ice of this 
description ; and I would suggest that the smooth contours of the 
islands to the north (and especially Walden Island, which we visited 
during our first expedition to the country) were impressed on those 
hard Archean rocks by sea-ice during the elevation, and not by 
glaciers originating on the mainland. It would be interesting 
to determine, if possible, wnether any particular boulder has received 
its characteristic glaciation during the forward movement of a glacier 
or during its voyage on an iceberg; but no definite distinction 
between the marks produced by these different modes of origin 
seems to exist. I was impressed, however, by the fact that the 
majority of the boulders collected from icebergs by the Jackson- 
Harmsworth Expedition appeared to possess one side much more 
definitely planed and polished than the rest of the block, and I 
found the same characteristic among many of the boulders which 
I examined on the spot. This feature is what we might expect in 
blocks carried by floating ice and ground against projecting reefs 
under water, for in this case the boulder would probably retain its 
original position in the ice until deposited on the melting of the 
berg, and would not be constantly rolled over in the ice in the way 
which must usually occur with fragments embedded in the lower 
layers of a moving mass of land-ice. It is possible that this fact 
may help to decide whether in some Glacial deposits the boulders 
have originated in land-glaciers or floating ice. 


688 _ MR. BE. J. GARWOOD ON THE [Nov. 1899, 


VII. Rock-scuLpruriné above THE SNow-Line. (Pl. XLVIII, fig. 1.) 


The snow-line in Spitsbergen is usually stated to reach sea-level. 
This is perhaps true as regards North-east Land, which appears 
to be covered by a continuous ice-sheet. In West Spitsbergen, 
however, especially on the western coast and in the neighbourhood 
of Ice Fjord, this is certainly not the case. The snow-line here 
lies somewhere about 1200 to 1500 feet above sea-level, and usually 
rises even higher by the end of August. The mountain-slopes along 
the coast at Mount Starashchin, King’s Bay, and elsewhere, and the 
lower slopes of the valleys of the interior, namely, Sassendal and 
Advent Vale, exhibit typical curves produced by the action of 
running water. 

The character of the scenery above the snow-line presents a 
marked contrast to these flowing curves. They are replaced by 
angular contours and vertical precipices produced by the action of 
frost alone. These wild and jagged outlines are perhaps most 
noticeable in the cleaved and foliated Archean and Hekla Hook 
formations, a good example of the latter occurring in the range of 
the Hornsunds Tinde in the south of the island (Pl. XLVIIL, fig. 1). 

The rocks of the Carboniferous dolomite-series are carved into 
pyramidal masses with vertical chimneys and horizontal ledges, 
recalling the well-known Dolomites in the Austrian Tyrol, and 
frequently presenting inaccessible faces. Many fine examples of 
peaks of this type occur in the centre of King James’s Land, where 
the Three Crowns and their neighbouring summits have been carved 
out of an horizontal plateau of Permo-Carboniferous strata which 
once completely covered this district. The curved slopes of the 
pedestals on which they stand are formed of copious screes from 
frost-riven Devonian shales. On the upper plateaux that flank the 
Sassendal and Advent Vale the same effect of frost is conspicuous: 
in this case, however, the horizontal bedding and unequal hardness 
of the Triassic and Jurassic rocks have caused a series of terraces 
to be produced. 

In speculating as to whether, in former times, the ice-sheets 
attained a greater thickness than at present and submerged the 
mountain-tops which now stand out as nunatakkr, it has been 
suggested that this angularity of the peaks rising from the midst of 
the ice demonstrates their continued freedom from any covering of 
ice even during Glacial times. 

The more the district is studied, however, the more evident 
becomes the fact that denudation is proceeding with a rapidity 
difficult for those to realize who are only acquainted with weather- 
ing in a temperate climate ; and I do not think that any argument 
can be drawn from the present angularity of the peaks above the 
snow-line. Itis only necessary to camp in the immediate proximity 
of a nunatak like the Pretender in King James’s Land, where 
fragments are falling continuously, and rock-avalanches occur every 
few hours; or to note the size of the medial moraines draining these 
rock-islands—to realize that a very few years would suffice to 
remove entirely any surface-features which might have been 


Geol. Soc. Vol. LV, Pl. XLI. 


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BESS IN FEET. 
East of Greenwich 18° 


TI” 


Vol: 55.| GLACIAL PHENOMENA OF SPITSBERGEN. 689 


impressed on them in former times. The presence of boulders of 
diabase on the plateaux of Sticky Keep in the ice-free Sassendal at 
an elevation of 1500 feet, where they must either have been raised 
nearly 1000 feet, unless the valley has since been excavated to that 
depth, or carried up on the surface of a glacier which attained that 
thickness, not to quote other instances observed on the island, is a 
sufficient proof of the former much greater extent and thickness of 
the ice in the district. 


EXPLANATION OF PLATES XLI-XLVIII. 


Pruate XLI. 


_ Outline-map of Central Spitsbergen, on the scale of about 14 miles to the 
inch, showing the radiating-points of the inland ice. 


Puate XLII. 


Panoramic view showing the main ice-streams entering the eastern end of © 
King’s Bay. 

The ice in the immediate foreground is derived from the local glaciers at the 
foot of Mount Neilson. Its motion is slow, it is uncrevassed, and it terminates 
on a flat of raised-beach material. The bulk of the glacier beyond (Crowns 
Glacier) is derived from the Highway Glacier and the ice-sheets north and west 
of the Pretender Range. Its motion is much slower, and it terminates in a 
vertical face from which icebergs are calved. The estimated advance of the 
main mass is 25 to 30 feet in 24 hours. 

The mountain-ranges extending across the island from Mount Neilson are 
composed of Hekla Hook Beds, and form the southern boundary of the King’s 
Highway. The range marks a line of thrust against which patches of Car- 
boniferous rocks have been let down, and this thrust-plane no doubt determined 
the original direction of King’s Bay. Views obtained from the summit of 
Mount Neilson show that the country south of the range is mountainous, and 
not covered with an ice-sheet as indicated on the chart. 

The centre of the view is occupied by two nunatakkr. The larger of these, 
on the right, is formed of Carboniferous Limestone, exhibiting a thrust-plane 
between the lower and upper beds. The more distant nunatak, on the left, is 
of Devonian conglomerate similar to that of which the islands in the bay are 
formed. 


Pruate XLITI. 


The terminal front of King’s Glacier: the thickness of the ice showing above 
sea-level is about 100 feet. 
I=South-east Islands (see panorama, Pl. XLII). 
M= Englacial moraine, elevated and thrown out at the end of Neilson Glacier, 
about 50 or 60 feet above sea-level. 


Puate XLIV. 


Icebergs calved from King’s Glacier at half-tide. View taken at midnight, 
looking south-east from sthe north-west islands of Devonian conglomerate 
shown in the panorama (Pl. XLII). 

The undulating shore-line AB is formed of Permo-Carboniferous dolomitic 
limestone, and the thrust-plane already mentioned runs between it and the 
mountain-range. From the icebergs shown in this plate the approximate 
rate of motion of King’s Glacier was deduced. Moraine-material is con- 
spicuously present on many of them, and some of it can be seen stranded in 
the foreground. Boulders from this showed the characteristic unilateral 
striation to which reference is made on p. 687. Attention is also directed to 
the Corrie Glacier, examples of which were described in a former paper, Quart. 
Journ. Geol. Soc. vol. liv (1898) p. 200. 


690. MR. E. J, GARWOOD ON THE [Nov. 1899, 


PLATE XLV. 


A collapsed ice-tunnel near Pretender Peak. 
The view is taken inside the tunnel, which is about 8 feet high: other 
tunnels are seen in the distance. 


. Prats XLVI. 


Fig. I. Ice-tunnels formed against the Pretender Range. 

Bird’s-eye view, to show the manner in which the ice-bridges are 
ridged up into parallel tunnels by the pressure of the ice against the 
barrier opposed to it by the range. A nearer view of some of 
these tunnels is shown in Pl. XLV. 

Fig. 2. View of nunatakkr causing elevation of englacial material. 

This not only constitutes an interesting example of the way in 
which the ice is ridged up on the impact-face of the nunatak (A), but 
affords a striking proof that the moraine-material frequently found in 
connexion with this upridging of the ice is not thrown off from the 
nunatak around which it occurs, but is in reality upraised englacial 
material. In the present example, the upper nunatak (B) and the 
moraine that encircles the impact-face of A are both formed of 
Archzxan rock, while the nunatak A is composed of Carboniferous 
dolomite. 


Puats XLVILI. 


Fig. 1. Surface-stream on Highway Glacier. (See p. 685.) 

Above the level of crevassed glaciers the ice-sheet is entirely drained 
by streams of this description, which frequently contain waterworn 
glacial material. The width of the torrent is about 15 feet, and the 
depth of the channel about 14 feet. 

Fig. 2. Englacial stream with moraine, King’s Glacier. 

The view shows an ice-tunnel 15 feet in diameter, which has been 
excavated by water escaping from a glacial lake immediately to the 
right of the picture. The moraine from a neighbouring nunatak is 
being carried into the tunnel, and waterworn fragments were found 
some distance from the entrance. The material lying on the floor of 
the channel is heaped up at right angles to the direction of the valley. 


Pruate XLVI. 


Fig. 1. The range of the Hornsunds Tinde, viewed from its southern extremity 
on Mount Hedgehog. 

This range has been entirely carved by frost out of Hekla Hook 
Beds, along the bedding and jointing shown in the picture, producing 
what has been aptly termed houseroof structure. 

The ice-sheet out of which the range rises is seen in the distance. 
In the immediate foreground the almost vertical precipices are coated 
with hoar-frost, which has formed to a depth in some places of 
18 inches, a product of the fogs that enshrouded the mountains during 
the three weeks preceding the day on which the photograph was 
taken (see Alp. Journ. vol. xviii, 1897, p. 378). 

Fig. 2. One of the erratics of the Archean moraine, Nordenskjéld Glacier. 

The boulder shown in this figure is one of the series described in the 
text (p. 684) as forming an independent moraine coinposed of isolated 
polished Archzan blocks, 4 to 6 feet in diameter. The view is taken 
looking down the glacier, towards the coast. 


[For other views of the district, supplementing in many respects those here 
reproduced, the reader may consult Geogr. Journ. vol. xii (1898) pp. 152-155). 


‘AdIOVID =NOSTIAN 


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| Quart. Journ, Geol. Soc. Vol. LV. Pl. XLII. 


Devonian N, W. Radiating Carboniferous P . : 
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pure Island. Islands. HI se ——__—_—__ Pretender. Pass. Pass. Range. Neilson. 
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Quart. Journ. Geol. Soc. Vol. LY. Pl. XLVI. 


| ICAETIE 


ICE-TUNNELS FORMED AGAINST THE PRETENDER RANGE, 


Figs2: B 


SWAN ELECTRIC ENGRAVING CO. PHOTO BY E. J. GARWOCD. 


VIEW OF NUNATAKKR CAUSING ELEVATION OF ENGLACIAL MATERIAL. 


Quart. Journ. Geol. Soc. Vol. LV. Pl. XLVI. 
EG jolts 


SURFACE-STREAM ON HIGHWAY GLACIER. 


Ric, 2: 


SWAN ELECTRIC ENGRAVING CO. PHOTO BY E. J. GARWOOD. 


ENGLACIAL STREAM WITH MORAINE, KING’S GLACIER. 


. 


f Te ay “ A Ley 


‘y 


en 


Quart. Journ. Geol. Soc. Vol. LV. Pl. XLVIII. 
Bice tr 


THE RANGE OF THE HORNSUNDS TINDE, FROM MOUNT HEDGEHOG, 
SHOWING FROST -DENUDATION. 


ice 2: 


PHOTO BY E. J. GARWOOD. 


SWAN ELBCTRIS ENGRAVING CO. 


ONE OF THE ERRATICS OF THE ARCHAZAN MORAINE, 
NORDENSKJOLD GLACIER. 


Vol. 55.] GLACIAL PHENOMENA OF SPITSBERGEN. 691 


Discussion. 


Mr. Marr said that not only had the Author confirmed the 
observations of others, but he had also made many new observations. 
Every glacial area should be studied by geologists, and each would 
no doubt contribute new facts of geological importance. The 
Author had spent two seasons in Spitsbergen; he was now about 
to start for the Himalayas, and he (the speaker) felt sure that the 
Fellows of the Society would wish him a successful expedition. In 
conclusion he wished to thank the Author for the admirable way in 
which he had presented his paper to the Society. 

Mr. Lamptvuee expressed his gratitude to the Author for the new 
facts, which all tended to confirm the deductions to be drawn from 
the glacial phenomena of parts of the British Islands with which he 
was acquainted. Time alone limited the number of pertinent 
- questions which might be asked in this connexion: he must be 
content now to enquire, first, whether the Author had observed 
any instance where the streams flowing on the ice-sheets had inter- 
sected emerging ridges of solid rock; and, secondly, to what extent 
the ice-fields would grow again under present conditions if they 
were entirely removed in this area. 

Mr. Satrer asked whether the Author had seen anything 
resembling the Boulder Clay and glacial gravel-deposits of Eastern 
and Central England, while examining the débris from the inland 
ice-sheets described by him. Such rapid denudation and other 
phenomena shown to exist in Spitsbergen, acting on the soft 
Jurassic Clays of Central England, would certainly be sufficient to 
bring about many, if not all, the effects of glacial and torrential 
action observed. 

The AvrHor, in reply to Mr. Lamplugh, thought that should an 
englacial river cut down to a transverse ridge occurring under the ice, 
such a col as was suggested would be produced; no such case, how- 
ever, was actually met with. He was strongly of opinion that the 
ice-sheets described were at one time much more extensive than at 
present, and that the greater part of the ice now covering the 
country was the result of accumulation in former times; were 
the district freed from ice and given a fresh start at the present 
time, he did not think that ice would now accumulate to any great: 
extent. ‘This was proved by the existence of the ice-free area 
traversed in 1896, when the island was crossed from coast to coast 
without encountering more than one glacier which covered the 
extreme watershed. 


692 PROF. W. J. SOLLAS ON SILURIAN [Nov. 1899, 


37. Fossrts in the Untverstry Musrum, Oxrorp: I. On Siturtan 
EcuinorpEa and OpuiuroipEa. By Prof. W. J. Sotzas, M.A., 
D.Se., LL.D., F.B.S., F.G.S. (Read April 12th, 1899.) 


As the work of arranging the Geological Collections of the Oxford 
University Museum proceeds, much interesting material is brought to 
light. Some of this will be described from time to time; but as the 
descriptions will be undertaken by more than one observer, some 
advantage may be gained, if only in indicating the common source 
of the material, by bringing these contributions together under the 
title of ‘ Fossils in the University Museum, Oxford.’ In this com- 
munication I propose to treat of some Silurian Echinoidea and 
Ophiuriodea. 


The Family Eucladide. 


The interesting and remarkable fossil described by Dr. Woodward 
under the name of Hucladia Johnson has recently been placed by 
Dr. Gregory in a new family—the Eucladide, of which hitherto it 
has been the sole representative. We are now able to assign it 
companions, and to add to our knowledge of its structure, with the 
result, as I believe, of showing that a more fundamental distinction 
exists between this group and all other Ophiuroidea than between the 
two recognized subdivisions Ophiure and Euryale. The family 
must be relegated at least to a new order, which 
may be called the Ophiocistia. 

Before proceeding further, it will be necessary to clear up certain 
doubtful points in the anatomy of Hucladia Johnson. The exposed 
surface of the fossil was described by Dr. Woodward’ as the ventral 
aspect, and good reasons were given for this proceeding, attention 
being called to the fact that the arms originate from it, and that 
it bears the madreporite. The existence of vertebral ossicles is 
not asserted. A re-examination of the fossil led my friend, 
Dr. Gregory, to ascribe a dorsal character to its exposed surface ; 
and a curious pentagonal rosette in the centre, rightly interpreted 
by Dr. Woodward as the buccal armature, came consequently to 
be regarded, though with expressed doubt, as ‘ radial plates.’ 
A dorsal position of the madreporite necessarily followed, and, 
indeed, was claimed as an archaic character.* Certain markings 
associated with the fossil were described and figured by Dr. Gregory * 
as vertebral ossicles. 

The study of the new material which has come under my obser- 
vation, as well as of Eucladia Johnsoni itself, leads to the conclusion 
that Dr. Woodward was certainly correct in his determination of 
the aspect of his specimen and that the pentagonal rosette is the 
buccal armature, for it is interradial in orientation, and closely 
resembles structures obviously of that nature in the new Eucladid- 
forms to be presently described ; the ventral position of the madre- 


1 xiorn, a box, Lat. cista. 2 Geol. Mag. 1869, p. 241. 
3 Proc. Zool. Soc. 1896, p. 1040. - 4 Ibid. p. 1041, fig. 6. 


Vol 55.| ECHINOIDEA AND OPHIUROIDFA. 693 


porite is involved in the determination of the ventral aspect of the 
specimen. 

As regards the structures described as vertebral ossicles, their 
form is so obscure that additional evidence as to their nature was 
felt. to be necessary, and permission was asked, and very kindly given 
by Dr. Woodward, to have one of the arms of the fossil sliced across 
for closer examination. Dr. Gregory was good enough to have this 
operation carried out. Two arms were traversed by the section ; 
neither showed any indication of such a structure as had been 
imagined to represent a vertebral ossicle. One had evidently been 
broken along the median ventral line after death and crushed so 
that the broken ends overlapped (an overthrust on a small 
scale), but it contained no vertebral ossicle; the second arm had 
likewise been broken, and some loose plates were scattered in the 
interior, but it was not possible certainly to identify any of these 
with a vertebral ossicle, though some might possibly be open to this 
interpretation. 

A question arises as to the external skeleton of the arms. 
Dr. Woodward described them as covered by minute imbricated 
plates, the projecting points of which give it an extremely scabrous 
appearance. Dr. Gregory states that the arms have no external 
arm-plates, but are covered by a granular integument: by this, no 
doubt, he merely intends to express the opinion that the scales 
covering the arms cannot be correlated with those of recent 
Ophiuroidea. Transverse sections present no natural apertures by 
which tube-feet could be extruded to the exterior, and an examina- 
tion of the surface shows that it was completely covered by closely- 
arranged overlapping plates, which are of two kinds: one larger, 
prominently projecting, with thickened conical ends, exhibiting a 
tendency to become mucronate; the other smaller, thinner, and less 
projecting, with gently-rounded terminations. No openings are 
visible at any point of these heavily-armoured appendages. Dr. 
Woodward, and subsequently Dr. Gregory, have spoken of these 
appendages as ‘ bifurcated’ or ‘ branched’ arms. It is conceivable 
that they may be so, but such a view does not seem to be supported 
by evidence. Avoiding hypothetical terms, the appendages of each ray 
may be spoken of as a paired series, the members of which are 
gradually larger from the mouth outwards. There are seven pairs 
in each series, of which the first or most proximal is situated on the 
buccal armature, taking its origin from one of the plates of the 
dental rosette. If the arms were provided with vertebral ossicles, 
and if these articulated with a series of similar ossicles arranged 
along a radius, the term ‘bifurcate or branching arms’ might 
perhaps be appropriate, but there is not the least evidence that this 
is or ever was the case, though a branching of the nerves and 
vessels supplying the arms must be conceded. The succeeding 
pairs pass out from a series of openings on the ventral side of the 
‘ disc,’ and there is a separate opening for each appendage, so that 
on the removal of these bodies a paired series of holes is left in the 
walls of the test. 


Figs. 1 & 2.—Eucladia Woodwardi, sp. nov. Reconstruction, 
dorsal and ventral aspects ( x 2). 


[One arm, the most proximal of the radius on the lower right-hand corner, 
is omitted, so as to show the aperture from which it proceeds. ] 


Vol. 55. | SILURIAN ECHINOIDEA AND OPHIUROIDEA. 695 


Kuctap1a Woopwakrbdt, sp. nov. (Figs. 1 & 2.) 


Certain star-fishes which have long lain in museums without a 
name, as being too problematical for determination, prove on close 
examination to be species of Hucladia; but so different is their 
aspect, owing to the difference in the state of preservation, that no 
one at first glance would have suspected their true nature. After 
first placing these forms in a new family, and then in a new s«*s, 
I am at last led to describe them merely as a new species. Ali the 
known examples of Hucladia Woodwardi, which is dedicated to the 
author of the genus, occur as hollow, ochre-stained casts in a matrix 
of fine-grained sandstone of Lower Ludlow age, Leintwardine. The 
Oxford University Museum contains no less than nine specimens, and 
there is one in the British Museum (Natural History); of these 
ten, five show the exterior dorsal surface and five the exterior ventral 
surface. All agree in presenting five paired series of appendages, 
proceeding from the ventral surface of the body, which now possesses 
a more or less oval outline. The specimens are all of nearly the 
same size, the central body measuring about 2x3 em., the longest 
arms 2°5 em. in length, and about 3 mm. in breadth where broadest. 
Not more than four, possibly only three, pairs of arms can be traced 
in connexion with each radius, but an additional pair may have 
existed close to the buccal armature, and have since become crushed 
out of recognition. 

The dorsal surface (fig. 1)—This is completely covered by 
numerous rounded polygonal or irregular scales, about -2 mm. 
thick and not exceeding 5 mm. in diameter; their surface is 
richly granulated. They are not arranged according to any dis- 
coverable law, though there may be a tendency to run parallel with 
the ambitus. In their present state they overlap each other to 
such an extent that one plate may be half concealed by another ; 
no doubt they were imbricated during life, but the excessive overlap 
now presented is probably in part due to crushing. The direction 
of the imbrication is upward, that is, in the direction opposite to 
that of tiles on a roof, and thus resembles the imbrication of the 
dorsal surface of a recent Ophiuroid. The plates are all of the 
same nature, and there are no openings on the dorsal surface. 

The ventral surface (fig. 2).—In the centre the powerful 
buccal armature is a very conspicuous object. It consists of five 
pairs of strong plates or ossicles, precisely similar in their form and 
arrangement to those of Hucladia Johnsom. Around the armature 
are numerous small plates, irregularly disposed; from their form 
and size these may be regarded as elements of the test, though they 
may possibly include remains of crushed arms. If, as judging from 
analogy we might suppose, minute arms proceeded from the outer 
angles of the jaws, they have since disappeared. 

Outside the irregularly scattered small plates larger ones are seen 
arranged: along the five radii these are escutcheon-shaped, imbri- 
cated, and form a single series of three. Distally, each plate is 
produced into three processes, a single median and two lateral ; 
the angle formed by the side of the plate and each lateral process is 


696 PROF. W. J. SOLLAS ON SILURIAN [Nov. 1899, 


rounded and thickened to form one side of a circular aperture for 
the passage or insertion of the arm, and the other half of the aperture 
is completed by the thickened margin of a similarly excavated 
adjacent or adradial plate. The adradial plates form a pair, which 
meet in the interradius. The arrangement is similar to that which 
occurs in the genus Huthemon, to be next described; in the latter, 
however, the plates are not overlapping, but tesselated. The over- 
lapping of the plates is less on the ventral than on the dorsal side, 
a difference which is probably due to the less amount of displace- 
ment suffered by the ventral plates ; and this, again, is explicable on 
the assumption that the ventral surface was flatter than the dorsal. 

The arms.—The arms of this species do not exhibit that 
marked increase in size, as their position in the series becomes 
more distal, which is characteristic of Hucladia Johnsoni. Their 
average length is 25mm. Near their tapering extremities the arms 
present on both dorsal and ventral surface three plates, two of 
which are lateral and one median, recalling the characteristic 
plating of an Ophiuroid arm ; but nearer the origin the number 
of conspicuous plates on either surface is increased to four or even 
more, and smaller supplemental plates are inserted between them 
in a manner precisely similar to that already described in the case 
of Eucladia Johnsoni. The larger plates, swollen at first and 
becoming mucronate finally, are produced into a short awn-like 
termination. | 

A search, which proved unsuccessful, was made for some trace of 
vertebral ossicles: had these structures been present originally, 
they must either have been very small or some traces would still be 
discernible. In Lapworthura, which occurs in the same rocks, the 
vertebral ossicles are the most obvious elements in the brachial 
skeleton. 

The distinction of Hucladia Woodward: from E. Johnsoni rests 
on the smaller number of arms possessed by the former and the 
closer approach of these to equality in dimensions. The specimen 
selected as the ‘type’ is exhibited in the Oxford University Museum, 
and bears a label stating where its description may be found. 


EvrHEMON’ IGERNA, gen. et sp. nov. (Figs. 3 & 4, p. 698.) 


This dainty little star-fish bears the label ‘ Crinoid ?, Croft Farm,? 
Wenlock Limestone.’ It retains its calcareous composition, and 
lies embedded in limestone with the oral surface uppermost. The 
portion preserved consists of the remains of a depressed spheroidal 
or subpentagonal test, several pairs of arms, and the buccal 
armature. 

The arms much resemble those of an Ophiuroid in outward 
appearance, but proceed from the test in pairs, as in Hucladia: a 
single arm on one side of a radius having its fellow symmetrically 
placed on the other. There were at least two pairs of arms to each 
radius, or twenty arms in all. Additional pairs may have been 

1 ebOnuwr, well-made. 
* Croft Farm is situated in the Malvern district. 


an agg a ae 


Velcnes| ECHINOIDEA AND OPHIUROIDEA. 697. 


present originally, but if so they have left no traces of their exist- 
ence. ‘The arms of the distal pairs are the larger, measuring from 
12 to 13 mm. in length, and about 1:5 mm. in breadth where 
widest ; thence they taper to the extremity. The number of 
joints is about thirty. The smaller proximal arms cannot have 
much exceeded 5 mm. in length. 

Three plates, which (without asserting any homology) may be 
compared to the lateral and ventral plates of a recent Ophiuroid, 
occur in each joint of the arms; their ends are pointed, but not 
spined. There are indications of the presence of a fourth or dorsal 
plate. The existence of vertebral ossicles is doubtful, and though 
it might be inferred from the general character of the arms, yet 
there is important negative evidence to the contrary. Thus, in the 
case of two of the larger arms, which possess well-preserved lateral 
plates but have lost the ventral plates, the interior is merely filled 
with matrix presenting no signs of ossicles, nor on clearing out the 
interior with a brass point could any trace of such structures be 
brought to light. It would certainly seem unlikely that the con- 
ditions which allowed of the persistence of the lateral plates should 
have proved so much less favourable to the vertebral ossicles, which 
are usually the more massive of the two structures. 

The test measures from 7 to 8 mm. in diameter; its ventral surface 
is incomplete, indeed has wholly disappeared, with the exception of 
a ring of polygonal plates in the region of the ambitus. Fifteen: 
_ plates enter into the composition of this ring; five are single and 
radial, while five are paired and interradial or adradial. ach of the 
radially-situated plates is the most proximal of a series of three, the 
second of which is cruciform in outline, and the last much smaller 
and almost square. The adjacent distal corners of the first radial 
and its neighbouring adradial are excavated so as to bound a semi- 
circle, which is completed and converted into a circular aperture by 
the rounded angle of the cruciform plate, and by an additional 
element which may be regarded as a second adradial. Through 
this aperture an arm of the first pair proceeds. The second pair of 
arms proceeds from a similar but larger aperture which is bounded 
by the distal angle of the cruciform plate, and by additional’ plates 
which are not clearly enough revealed for description. By a careful 
removal of the matrix the sides of the test have been partly exposed 
to view. A single polygonal interradial plate, relatively large, lies 
between the two adradial plates above, and on each side of it 
another polygonal plate is seen, but its relation to the radial plates 
is hidden by the arms which overlie it. 

The dorsal surface, owing to its envelopment in the matrix, is con- 
cealed, but by cleaning out the interior of the test a glimpse of part 
of it may be obtained from within; the central region, however, 
remains covered by the buccal armature. Few details can be made 
out, but it is clear that the roof of the test was as compactly built 
as the sides ; it presents itself as a continuous calcareous sheet, in 
which the existence of five comparatively large radial plates is 
barely suggested. 

Q.J.G.8. No. 220. 22 


Fig. 3.—Euthemon igerna, gen. et sp. nov. Specimen showing the 
ventral aspect, magnified nearly 3 diameters. 


La isep ethos 
a 
Sad. 


* 


RIS FLO S Foxe 
ERLAROCS Rrecner sin’ 


Vol. 55.] SILURIAN ECHINOIDEA AND OPHIUROIDEA. 699 


The buccal armature’ occupies the greater part of the interior 
of the test. It consists of five strong pieces, interradially placed, and 
meeting in the centre to form the dental rosette. Hach piece appears 
to be traversed by a median longitudinal fissure, and is probably 
composed of a pair of ossicles. 

The genus Huthemon differs from Hucladia in the absence of 
imbrication of the plates that form the test. 


On a review of the characters presented by the three species just 
described, it will be admitted that their affinities are with the 
Ophiuroidea. The absence of any openings on the dorsal surface, and 
of any indication of an anus, the ventral position of the madreporite, 
and the sharp distinction of the arms from the test indicate this 
much. On the other hand, they differ from all known Ophiuroids 
in several important particulars. 

The structure and disposition of the arms is unlike anything 
known among either the Ophiure or the Euryale, and finds no 
parallel among any group of fossil Ophiuroidea. If we consider the 
disposition of the arms first, we find as a constant character among 
the rest of the Ophiuroidea the extension of five of these appendages 
over the ventral surface of the disc as far as the buccal aperture: 
the vertebral ossicles of the arms are also serially represented in 
the buccal armature. In the Eucladide also the arms are given off 
from the ventral surface of the test, and the first pair have their 
origin in the outer distal angle of the jaws: if, however, we are to 
regard the serial arms of Eucladide as the free extremities of lateral 
branches given off in pairs from a median hypothetical arm, then 
we must admit that the branching takes place within the test to an 
extent otherwise unknown within the class.” If we turn next to 
the structure of the arms, we find no less striking peculiarities. No 
decisive evidence exists to prove that vertebral ossicles are present, 
but if they are they must be out of all proportion small compared with 
the lumen of the arm. Since the cavity of the arm is almost entirely 
unoccupied by skeletal structures, the question naturally arises as to 
the nature of the soft parts which it contained. The distal arms are 
so large that they might well have afforded room for extensions of 
the digestive viscera from the test. The absence of visible apertures 
in the armsis another very puzzling feature, and one is almost tempted 
to enquire whether the paired appendages are to be compared 
with arms at all. 

The nature of the buccal armature is very different from that 


1 The buccal armature is seen in the middle of fig. 4, separated by an annular 
space from the wall of the test. This space was probably covered in the living 
animal by a buccal membrane. 

2 In connexion with this, Mr. Minchin has called my attention to the 
remarkable Ophiuroid described by my friend Mr. W. P. Sladen under the name 
of Astrophiura permira, Aun. & Mag. Nat. Hist. ser. 5, vol. iv (1879) p. 401. It 
presents several striking analogies with the Ophiocistia. The arms are not 
paired, it is true, but single and much reduced ; they are, however, incorporated 
with the test to an unusual extent. The vertebral ossicles are peculiar and 
rudimentary, and the buccal armature is more Asteroid than Ophiuroid in 


character. 
Poe 


700 PROF. W. J. SOLLAS ON SILURIAN [Nov. 1899, 


of any other Ophiuroid, though there is a certain amount of corre- 
spondence in the paired structure of its five pieces. The absence 
of any opening that could be taken for bursal apertures is note- 
worthy. 

The position of the Eucladide is altogether anomalous, and 
requires at least ordinal recognition, I propose therefore to place 
the group in a new order, the Ophiocistia, to rank as of the 
same value as the Euryale. The Ophiocistia are Ophiuroidea with 
five paired series of appendages, proceeding from the ventral surface 
of a plated test; and in which vertebral ossicles are absent or 
insignificant. 


MyrrasTicHas ciegas, gen. et sp. nov.’ (Fig. 5, p. 701.) 


This remarkable form, presumably a sea-urchin, forms part of the 
Grindrod Collection, acquired by purchase, and is labelled in different 
handwriting ‘ Fish?’ and ‘ Palmipes?’ The second is a better 
guess than the first, inasmuch as the fossil is evidently an Echino- 
derm ; as to its class there is less certainty, but most probably its 
affinities are with the Echinoidea. , 

In the living state Myriastiches had the form of a large sac with 
very thin walls, so that on death it suffered collapse, and now lies 
flattened out in a shaly limestone of Lower Ludlow age. Some 
mud from the sea-floor seems to have penetrated to the interior, as 
the opposite walls are separated by a thin layer of foreign material. 
Only a part of the organism is visible on the surface of the slab in 
which it lies; the rest is partly concealed within the matrix, and 
partly has been lost in extricating it. The whole of the flattened 
sac measures approximately 10x15 cm.; the part which is fully 
exposed to view measures 8 X 12 cm. 

The ambulacral areas occupy an insignificant portion of the test, 
which is thus almost wholly interambulacral. The 
interambulacral areas are composed of exceedingly numerous and 
consequently minute calcareous plates, which are almost square in 
outline, with rounded corners ; they become hexagonal apparently 
by truncation of opposite corners of the square. They measure 
0-75 mm. in length and breadth, and about 0°15 mm. in thickness ; 
the plates are closely tesselated together, though occasionally with 
a slight degree of imbrication, the overlapping edges being adjacent 
sides of the square, so that a lozenge-like design results. The 
characteristic appearance resulting from the number and minuteness 
of the interambulacral plates no doubt suggested the reference to 
Palmipes ; it finds no parallel among known Kchinoidea. A few 
granules, not more than two or three, occur on some of the plates, 
but there is a remarkable absence of any indication of spines. 

The number and disposition of the ambulacral areas cannot be 
determined. There is one which extends right across the fossil, and 
a small fragment of another, which runs for some distance round the 
margin. The ambulacra were probably abnormal; if five areas had 


1 orixos, a row or rank, 


Voless.|) ECHINOIDEA AND OPHIUROIDEA. 701 


existed with the usual arrangement, more evident signs of them 
might be naturally expected. The specimen is, however, somewhat 
overfolded and overthrust, so that additional ambulacra may easily 
exist concealed. 

The breadth of an ambulacral area is 3°5 mm.; it is composed of 
two rows of narrow plates bearing double pores (fig. 5). The 
length of a plate is 1°75 mm., 
its breadth about 0°32 mm., so Fig. 5.—Ambulacral and adjacent 


that on the average there are interambulacral plates of 
two ambulacral to each adjacent Myriastiches gigas, gen. é 


interambulacral plate. The pair sp. nov. (X about 9). 
of pores is situated in that moiety 

of the plate which helps to form 
the median ambulacral suture. 
The pore does not seem to be com- 
pletely defined by its own plate, 
an adjacent plate taking part in 
its boundary. ‘The character of 
the sutural line between the 
ambulacra and the interambu- 
lacra is inconstant: sometimes it 
presents itself as an approxi- 
mately straight line, the sides 
of square interambulacral plates meeting the truncated ends of the 
ambulacral; sometimes it is a zig-zag, corresponding to the angles 


f 
if 


OG 
NM 


made by adjacent hexagons when the interambulacral plates acquire — 


the hexagonal form. 

A hollow cast, lying in the midst of the flattened sac, appears to 
represent a single strong jaw, like that of an HKchinoid: of the 
apical region there is no indication. 

In the characters of the ambulacra Myriastiches makes an approach 
to the extinct Cystocidaroida of Zittel ; but if, as seems natural, the 
genus is to be included in that group, the diagnosis of the order as 
given by Dr. Gregory may have to be amended so as to admit of the 
reception of forms unprovided with spines. 

The differences between Myriastiches and the two other genera— 
Paleodiscus and Echinocystis—which so far form the contents of the 
Cystocidaroida, are more than generic, and require the institution of 
anew family, the Myriastichide, which may be thus defined :— 
Cystocidaroida in which the interambulacral areas are composed of a 
large number of rows of minute square plates, and the ambulacra of 
two rows of small plates bearing double pores suturally situated. 

Genus: Myriastiches, with the characters of the family. 


PaLzopiscus FEROX, Salter. (Figs. 6-11, pp. 702, 703, & 704.) 


The specimens in the Oxford University Museum are in the usual 
state of casts, only occasionally presenting remains of the original 
calcareous test and spines. ‘They afford views of the ventral surface, 
sometimes from within, sometimes from without; the dorsal surface 
is rarely exposed, and none of the specimens exhibit the apical 


Fig. 6.—Paleodiscus ferox : ventral aspect of peristomal region (Xap: 


Fig. 7.—Paleodiscus ferox : lantern of Aristotle seen from within (x 4). 


Vol. 55.] SILURIAN ECHINOIDEA AND OPHIUROIDEA. 703 


region. The largest example measures 5 cm. in diameter. In all 
cases the organism that furnished the cast has been compressed 
from above downward, never from side to side. A careful study 
enables me to supplement the excellent descriptions of Salter and 
Wyville Thomson in several important particulars. The plates of 
_ the test are all of them overlapping; the wide interambulacra 
become narrower towards the mouth, and cease at the peristomal 
margin, or are continued only a very short distance beyond by a few 
minute plates. The series of adambulacral plates is fairly regular, 
and the succeeding rows of the interambulacra maintain a rough 
parallelism with it. The ambulacral areas do not cease at the 
peristome, but are continued as far as the pointed ends of the jaws, 
the sides of adjacent ambulacra lying in contact immediately beyond 
the termination of the interambulacra (fig. 6). 

Dr. Gregory, after a comprehensive survey of the characters 
which have been regarded as diagnostic of the Echinoids, selected 
the disposition of the ambulacral plates as a decisive criterion 
in the case of Palwodiscus, and, asserting that these lie flush with 
those of the interradii, pronounced in favour of its relationship to the 
Kchinoidea: a conclusion doubtless correct, but deduced from false 
premises, for the ambulacra do not possess the characters assigned 
to them, and it is to the buccal apparatus that we must turn for 
convincing evidence of the true nature of Paleodiscus. 

The buccal armature (fig. 7).—The ventral surface seen from 
within affords an excellent study of the ‘lantern.’ Most con- 
spicuous are five strong rectangular bars with rounded corners 
situated radially; on either side of each of these a strong ridge is 
seen, which widens out flange-like distally. If these ridges represent 
the ‘epiphyses’ of the alveoli, then the rectangular bars can 
scarcely be other than the intermediate piece or ‘rotula.’ The 
epiphyses do not meet interradially as in recent urchins. In 
addition to these elements a third is sometimes met with which 
presents a strap-like form, bifurcate at the distal end. If this should 
be the ‘radius,’ as I believe it to be, it must have suffered some 
displacement, since it is never seen lying immediately over the middle 
line of a rotula. 

In addition to these elements, teeth of Echinoid character are 
present ; traces of them may 
still be seen in connexion Fig. 8.—An isolated tooth of 
with the ‘lantern, and in Paleodiscus ferox ( x 9). 
one instance an_ isolated 
tooth (fig. 8), freed from its 
sheath, lies fully exposed 
over the surface of an 
interambulacrum. It is composed of denser material than the other 
ossicles of the skeleton, and in consequence appears less opaque ; 
it has an elongated lancet-like form, is sharp at one extremity, 
longitudinally grooved, and divided at the other extremity by a 
single furrow ; its length is 5:5 mm., its maximum breadth 0-2 mm. 

The close relation of Paleodiscus to the Echinoidea being thus 


Fig. 9.—Transverse section through an ambulacrum of 
Paleodiscus ferox ( x 12). 


0. 


[The uppermost line was obtained from a transverse section of a wax im- 
pression of a hollow cast: the remaining lines are restored from a general 
study of the ambulacra. The thin lines are entirely hypothetical. | 


Figs. 10 & 11.—Ambulacrum of Paleodiscus ferox: hollow casts — 
from the vicinity of the mouth and the ambitus respectively ( x 12). 


[The lowermost figure shows the median zigzag sutural line of the outer or 
Echinoid ambulacral plates, on a central ridge formed by the sandstone which 
fills the hollow of the ambulacral groove. The more darkly shaded areas repre- 
sent the cavities left by the inner or Asteroid series of ambulacral plates: 
the light circular processes at the margins of these represent one pore of a pore- 
pair—its fellow is not very conspicuous in these casts. | 


Vol. 55.] SILURIAN ECHINOIDEA AND OPHIUROIDEA. 705 


definitely indicated by the nature of the buccal apparatus, the in- 
vestigation of the ambulacra acquires additional interest, since it 
affords an opportunity of discovering the precise stage at which these 
important organs had arrived in the course of evolution during early 
Paleozoic times. The structure of the ambulacra is more compli- 
cated than has been supposed, or than is suggested by a study of 
the fossil in its usual state of preservation. All that can be usually 
seen in ordinary casts of the oral surface is a furrow, which 
represents the ambulacral groove, whence the plates have wholly 
disappeared, leaving, however, impressions, which prove clearly that 
they did not lie flush with the plates of the interradii. In better- 
preserved examples the furrow is seen to be bordered, even on the 
oral side of the test, by a row of pores, 0°19 mm. in diameter, - 
usually single, more rarely double, situated at the point of flexure, 
where the ambulacral plates bend inward to form the ambulacral 
groove. The form of the groove in transverse section, as shown in 
fig. 9, can readily be made out by taking a cast in wax, and slicing 
this across. The ambulacra do not appear to have been limited to 
the oral surface, since, in addition to the impressions which regularly 
radiate over this aspect, fragments of others may be detected: these 
can only have been derived from the aboral surface which has been 
squeezed down into contact with the oral. In the examples just 
described the ambulacra present a remarkable resemblance to those 
of an Asteroid, although I think the pores do not, as Dr. Gregory 
supposed, lie between adjacent ambulacral plates, but are confined 
each to a single plate, as in modern urchins. 

In unusually well-preserved specimens additional features may be 
observed. A shelf of the matrix, bearing on its outer surface the 
impressions of additional plates, is found to roof over the ambulacral 
furrow, and partly conceals the ambulacral plates or their casts, 
which dive beneath it and appear as a row of slanting tubes 
(figs. 9 & 10). 

A single specimen exists in the Oxford University Museum 
wherein some of the original plates of the test, displaying the 
characteristic mesh-structure of recent Echinoids, are preserved. An 
examination of these fully confirms the inference that might be 
drawn from the best-preserved casts, namely, that each ambulacrum 
was provided with two series of paired plates, one forming its roof, 
the other its floor. The last set correspond to the ambulacral 
plates of an Asteroid, the former to those of an Hchinoid; and in this 
observation we find the clue to that long-standing riddle, the corre- 
lation of the ambulacra of Asteroids and Kchinoids. 

In some specimens the ambulacral plates are almost entirely 
~ concealed on the outer surface by the ‘ velvety pile’ of thin spines, as 
Wyville Thomson happily phrased it ; on the interambulacral plates 
these spines are far more sparsely scattered. 


As I was led to investigate the ambulacra of Palwodiscus by a train 
of a priori reasoning, it may not be out of place to indicate at this 
point the general direction of my argument. If we consider the 
relation between function and structure in the Ophiuroidea, 


706 PROF. W. J. SOLLAS ON SILURIAN [Nov. 1899, 


Asteroidea, and Echinoidea, we find a marked distinction between the 
first and the two latter, in the fact that the latter possess adhesive 
tube-feet, by which they are able to hold fast to the ground, and 
thus move surely though very slowly. The power of a large 
Echinoid to hold on to the perpendicular face of a rock, even when 
exposed to a heavy ground-swell, must have been often observed 
with surprise by the shore-collector. The Ophiuroid, on the other 
hand, is without adherent suckers, but makes up for their absence 
by its power of rapid movement. ‘The structure of the brittle-star 
is in complete adaptation to this faculty ; and its ambulacral ossicles, 
originally similar to those of a star-fish, have become modified to 
serve as the well-known vertebral column, which affords both 
protection to the nerves and vessels of the arms and attachment 
to the powerful longitudinal muscles by which these organs of 
locomotion are flexed. 

The Echinoids and .Asteroids are equally well adapted to their 
respective modes of progression. The tube-feet are lines along which 
tension is active; the pullis resisted at one end by the ground, at the 
other by the skeleton, which is constructed in an ideally perfect 
manner to withstand the pull. In ancient star-fishes the ambulacral 
ossicles were mere trabeculae lying parallel with the flat ventral 
surface, a very inefficient position: this, in the evolution of the race, 
they have exchanged for that which they now possess, namely, 
arrangement in the form of an arch. This arch isso deep that it not 
merely furnishes the required amount of resistance, but securely 
protects the underlying nerve and water-vessel. In the Echinoids 
such an arch would be rather a source of weakness, as interrupting 
the continuity of the closed, more or less spherical form, which is 
of itself sufficient to supply the requisite amount of resistance. 
Yet, if the ambulacra of Echinoids and Asteroids are to be considered 
homologous, it may be inferred that such an arrangement was at 
one time in existence. In such a case, what would be the probable 
course of transition from the primitive state to that which at 
present obtains ? One might conjecture that the discontinuity in the 
spherical form would be bridged over by a tangential growth, either 
of new plates, or of processes from the bases of those already 
existing. After this new growth had arisen, the original ambulacral 
plates, included within the test, would become functionless and 
might be dispensed with ; as useless organs they might be expected 
to disappear. Thus, by hypothesis, ancient urchins should have 
existed in which the ambulacral skeleton would unite both Asteroid 
and Kchinoid characters. It was this consideration that led me to 
investigate closely the ambulacral region in Palwodiscus, with, as 
we have seen, confirmatory results. 

The structure of the ambulacra in Palewodiscus forcibly recalls 
that of Mesites,’ which has likewise been regarded as a link between 

l Mesites Pusireffskit, Hoffmann, Verh. Mineralog. Gesellsch. Petersb. ser. 2, 
vol. i (1866) p. 1 & pl.i; F. Schmidt, Mém. Acad. Imp. Sci. St. Pétersb. ser. 7, 
vol. xxi (1873) No. 11, p. 34 & pl. iii; Neumayr, ‘ Die Stamme des Thierreiches,’ 
1889, p. 420; Steinmann & Deederlein, ‘Elemente der Palaontologie,’ 1890, 


p- 181; Heckel, ‘ Festschrift z. 70ten Geburtstage v. Carl Gegenbaur,’ vol. i 
(1896) p. 119. 


Vol. 55.] ECHINOIDEA AND OPHIUROIDEA. 707 


star-fishes and urchins. Heckel, however, among the latest writers 
on the subject, refers it to the Agelacrinide, and in doing so follows 
Zittel.. Lang has raised several objections to the inclusion of 
Mesites with the Echinoidea: he remarks?:—‘(1) Itis quite uncertain 
that the ambulacral vessel lay in this [the inner] canal, and not in the 
outer channel ; (2) the ambulacral feet, in Echinoids, pass through 
the ambulacral plates and not between them as in Mesites; and 
(3) it is not at all certain that the pores of Mesites really served for 
the passage of ambulacral feet.’ None of these objections, however, 
apply to Paleodiscus; and, considering the positive nature of the 
evidence afforded by this fossil, the position of Mesrtes becomes a 
matter of secondary importance, and one upon which I do not feel 
impelled to pronounce an opinion, especially as I have had no 
opportunity of examining actual specimens. 

Regarding the suggestions which have been offered as to the 
connexion between function and structure in the case of urchins 
and star-fishes, reference may be made to the ambulacral spines: 
these, on the theory propounded, are not merely protective in 
the usual sense, that is, against enemies, but serve as struts, 
preventing the tube-feet from pulling the body of the animal into 
immediate contact with the ground; and thus protect it from 
bruising and attrition. 

It is noteworthy that in Palwodiscus the test has not yet acquired 
the rigidity that characterizes the majority of Echinoids, and hence 
at this stage of development there is an obvious advantage in the 
possession of twofold ambulacra. As tesselation becomes more 
compact this advantage is diminished, and the Asteroid ambulacral 
series finally becomes functionless and disappears; except, and the 
exception is significant, in the case of the ambulacral auricule: 
these, as Johannes Miiller long ago divined, represent the otherwise 
lost internal ambulacral plates, and they have survived because they 
have a function to serve, namely, as processes of attachment for 
the retractor-muscles of the buccal armature. 


Ecuinocystis pomum, Wyville Thomson, (Figs. 12-14, pp. 708 & 
709.) 


Only one out of a series of seven specimens has been crushed 
from above downwards, all the rest are laterally compressed. The 
primary tubercles are centrally pitted or perforate. 

Sir Wyville Thomson asserted that teeth were borne by the outer 
ends of the alveoli; but Prof. Duncan questioned this, and regarded 
their presence in this position as accidental. It is difficult to 
be certain on this point. I have repeatedly observed appearances 
similar to those figured and described by Wyville Thomson; 
the spines have every appearance of being proper to the alveoli, 
but the buccal membrane, which bears similar spines, extends so 
close to the extremities of the alveoli, that the association with the 


1 Zittel, ‘Grundziige der Palzontologie,’ 1895, p. 157. 
? Arnold Lang, ‘ Text-book of Comparative Anatomy, Engl. transl. (1896) 
pt. ii, pp. 386, 387. 


oe? PROF, W. J. SOLLAS ON SILURIAN [ Nov. 1899, 


latter elements may be, as Duncan supposed, merely accidental. 
The question, which is of interest, owing to its connexion with that - 
of the origin of the pyramids, cannot be regarded as decisively 
settled. . 

Although teeth have not been observed, the alveoli, as seen from 
the front, that is, towards the axis of the test, present a deep groove 
similar to that which occurs in recent Echinoids, and which in 
them is occupied by the tooth. 

Although badly preserved, partly in consequence of the thinness 
of the plates, the ambulacra still display characters of interest: 
a row of minute tubercles borders them on the outer margin, and 
a double row of even smaller tubercles runs along each side of the 
middle line (fig. 12). The pore-pairs each lie in an oval depression 


Fig. 12.—Part of an ambulacrum of Fig. 13.—Part of the 
Kchinocystis pomum. same, more highly 
magnified. 


(peripodium), and those of the inner series are associated with 
the larger outer tubercles; those of the outer row are similarly 
associated with the inner tubercles (fig. 13). A considerable 
amount of irregularity disturbs this arrangement, attributable in 
some degree to imperfect preservation. It is probable, almost 
certain, that these ambulacral plates, so singularly Echinoid in 
character, are those of the outer or Echinoid series; the specimens 
in our collections are all, so far as I am aware, casts of the external 
surface only, and the exposed casts of the plates are consequently 
also superficial. The question then arises whether a second or 
internal set was also present. It is by no means impossible: in a 
single example in the Oxford University Museum a minute portion 
of the test is imperfectly preserved in carbonate of lime; sections 
made through this passed through one side of the ambulacrum, and 
exhibited the appearance shown in fig, 14. Had this structure 
continued throughout, no doubt could have been entertained on 
the point, and the existence of a second set of plates would have 
been proved; after twenty sections had been obtained in a space 
of 2 mm., the upper portion disappeared, possibly owing to the 


Viele 55. ECHINOIDEA AND OPHIUROIDEA. 709 


curvature of the ambulacrum, which removed it from the protecting 
influence of a thin layer of sandstone that covered it elsewhere. 


Fig. 14.—Transverse sections through the ambulacrum of a specimen 
of Echinocystis pomum partly preserved in carbonate of lime. 


On grinding deeper, evidence was obtained in favour of this explana- 
tion, so that on the whole the existence of an inner series would 
appear to be indicated. 


PROTOCIDARIS Sp. 


I had completed an account of this fossil when the last volume 
(vol. lii) issued by the Paleeontographical Society reached me; and I 
found very similar remains described there by my friend Mr. Whid- 
borne, under the name of Protocidaris acwaria, gen. et sp. nov.’ 
These are found in Devonian rocks, east of Barnstaple. Like many of 
the fossils from Leintwardine, the specimen in the Oxford University 
Museum (Grindrod Collection) presents casts of the original structures, 
more or less iron-stained, but in some cases preserving some of the 
original calcareous substance. Spines and interambulacral plates are 
allthat remain of the organism, which most probably was an Echinoid. 
The plates are thin, irregularly oval or round, measuring 3x5 mm. 
in some instances; they are minutely granulated and bear a widely- 
perforated central tubercle, which does not appear to have been seated 
on a boss. The spines are of two kinds, a smaller, 2 or 3 mm. long, 
and a larger, as much as 13 mm. long, truncated at the head, which 
is deeply and widely excavated like the mamelon ; no longitudinal 
striations are now visible. 

It would not be prudent to give these remains a specific name, 
for they may belong to the same species as that described by 
Mr. Whidborne; the only points of difference now discoverable are 
the absence of a boss and of striations on the large spicules, 

On closer examination of Hchinocystis, a marked resemblance 
between the interambulacral plates of this genus and those of 


1 Lom. cit. (1898) p. 203 & pl. xxv, figs. 1-2 a. 


710 _ PROF. W. J. SOLLAS ON SILURIAN [Nov. 1899, 


Protocidaris appears, and it is quite possible that both Mr. Whid- 
borne’s specimen and that in the Oxford University Museum may 
represent an unusually large form of Echinocystis. 


The general question of the evolution of the Echinoids 
is greatly elucidated by a study of the Palwodiscus and Echinocystis 
just described. The comparatively early appearance of the Asteroids, 
as shown by the occurrence of Palcasterina in the Tremadoc Slates 
of St. David’s, and the marked Asteroid affinities of the Silurian 
Ecbinoids, particularly of Palwodiscus, suggest that the Echinoid 
branch has been directly derived from the Asteroid, rather than 
that both have descended from a common stock. 

Adopting the former as the more probable hypothesis, it has 
already been shown that the ambulacral plates of the Echinoids 
may be regarded as the survivors of what was once a twofold 
series, and an attempt may next be made to find an interpretation 
of that complex buccal armature, ‘ Aristotle’s lantern.’ This is by 
no means an easy task. Dr. Gregory has taken a first step, in 
conjecturing that the pyramids may have been produced by a 
modification of ambulacral plates; and if this be not precisely 
true, it is at least suggestive. 

It may be observed at the outset, that the pyramids of the 
lantern lie, like other plates of the true KEchinoid test, superficial 
to the water-vascular system, and hence must be correlated with 
the outer and not the inner ambulacral series of Pulwodiseus and 
its allies. But the buccal armature evidently arose very early in 
the development of the phylum, possibly even determined its origin, 
and consequently the outer ambulacral series, from which we 
imagine the lantern to have been mainly derived, must have also 
made its appearance at a very primitive stage. Neumayr, who 
pointed out the significance of the structure of the ambulacra in 
Mesites, and suggested an explanation of the ambulacral system of 
the Echinoids similar to ours, asserted that a superficial series of 
plates occurs outside the radial nerves and water-canals in young 
Asteroids, and subsequently disappears. If so, the twofold series 
may be regarded as originally common to the two groups: the 
outer, becoming functionless with the arching of the ambulacra, was 
lost in star-fishes ; while the inner, becoming functionless as the test 
acquired rigidity, was lost in the Echinoids. 

A comparison of the buccal armature in star-fishes and urchins 
reveals a certain general resemblance. In the former a pair of 
jaws, recalling the alveoli of Echinoids, are braced together by the 
‘odontophore’ in much the same way as the pyramids of the 
lantern are united by the rotula: which, it may be added, lies 
deeper than the water-canal, and thus recalls an Asteroid relation- 
ship. The jaws of the star-fish bear spines; the alveoli of the 
urchin carry each a tooth. The odontophore occupies an inter- 
radial, the rotula a radial position ; and the surfaces of muscular 
attachment of the jaws or pyramids (strangely similar in the two 


Vol. 55.] ECHINOIDEA AND OPHIUROIDEA. Tut 


cases) are distinguished by a like difference in position: so that it 
would seem necessary to rotate Aristotle’s lantern through an angle of 


= to bring it into homologous relations with the buccal armature of 


star-fishes., 

The structure of the Asteroid armature has been correctly 
analysed by Ludwig, who has illustrated by a diagram the manner 
in which the jaws have arisen by modification of the first, 
pairs of ambulacral and adambulacral plates: this diagram might 
almost stand for a drawing of the mouth-parts in Palwocoma 
Marstoni, a fossil Asteroid of Lower Ludlow age. From this we 
learn that the first pair of ambulacral plates, losing the parallelism 
which prevails in the arm, diverge from each other to overlap near 
their termination the enlarged first adambulacral plates, which bear 
the teeth or, rather, spines. In urchins, on the contrary, there 
appears to be no splaying-out of the enlarged ossicles at the com- 
mencement of an ambulacrum, and the muscularly-attached sides of 
the alveoli continue in the radial direction. ‘The alveoli are, how- 
ever, generally regarded as interradial in nature; and from this it 
seems to follow that while in star-fishes the ambulacral ossicles have 
diverged to meet in an interradius, in urchins on the contrary it is 
the adambulacral ossicles which have diverged to meet along the 
radii. 

At this stage of our enquiry we receive important aid from 
ontogeny. The diagram on the following page is taken from Lovén’s 
faithful drawing of the mouth-parts in a young specimen of Gonio- 
cidaris canaliculata, A. Ag., 1'45 mm. in diameter (fig. 15). The 
hemipyramids are seen to be interradial in position, and on our 
hypothesis represent the first pair of adambulacral plates; the 
epiphyses are as truly radial, and may be regarded as the first pair 
of ambulacral plates. Immediately over the interradial line, where 
the two hemipyramids meet, lies a plate which subsequently becomes 
the tooth; it occupies a position precisely corresponding to that of 
the odontophore in Asteroids. In a second illustration, the buccal 
ossicles of the same specimen are represented as seen from the side 
(fig. 16, p. 712). This is an extremely instructive view: the epi- 
physes or ambulacral elements are shown lying above the pyramids, 
as they should do if of ambulacral origin; and, further, they are 
obviously divergent from the radial plane, or convergent towards the 
interradius, thus recalling the splaying-out of the first pair of ambu- 
lacral ossicles in the jaws of star-fishes. 

So far the resemblance between the buccal armature of a young 
urchin and that of a star-fish would appear to be complete, and it 
would be difficult not to see here a case of precise homology, were it 
not for the difference in the relations of the two sets of ossicles to 
the water-vascular system ; yet, since this difference does certainly 
exist, we are driven to conclude that the resemblance is but another 
instance of that far from uncommon phenomenon which Ray 
Lankester has designated ‘homoplasy.’ The young specimen just 
mentioned presents rudiments of both rotula and radius, which, 


Fig. 15.—Goniocidaris canaliculata, A. Ag. (After Sven Lovén,’ 
‘ Echinologica,’ Bihang till k. Svensk. Vetensk. Akad. Hand. 
vol. xvitt, 1893, pt. iw, pl. ivi, fig. 22.) | 


i{The above figure gives an inside view of the peristomal plates I, 5, & V, 
showing half-pyramids of 5 with tooth, and the muscles (m.re, m.pro) 
attached to the solitary peristomal 5; the beginnings of the epiphyses 
(ep.) and of the rotula (ro.).] 


Fig. 16.—Side view of the buccal armature of Goniocidaris canaliculata. 
(After Loven, op. supra cit. fig. 23.) | 


[The above figure shows the raised half-pyramids beginning to enclose the 
teeth, also the radius and rotule. | 


Vol. 55. | SILURIAN ECHINOIDHA AND OPHIUROIDEA. (Ss 


as we have learnt from Palcodiscus, made their appearance very 
early in the phyletic development of the Echinoids. They occupy 
in the young specimen the same position as in the adult, and, as 
in Palcodiscus, lie one above the other in the radial plane. It 
is difficult to discover homologies for these parts, but since they 
lie above the water-vascular canal they may be assigned to the 
Asteroid and not to the Echinoid system of the ambulacrum. In 
ancient and primitive star-fishes the ambulacral plates are said to be 
alternately, not oppositely, disposed; and if this be the case, the 
suggestion arises that the radius and rotula may correspond to a 
pair of ambulacral ossicles, which have been pushed one over 
the other in the course of development. The elongation and diver- 
gence of the Echinoid ambulacral plates to form the epiphyses: 
would carry the Asteroid ambulacral ossicles in its course, and 
during this translation a displacement might conceivably arise. 
Such a view, however, is difficult to harmonize with the symmetrical 
arangement of the muscles of the radii. The radius indeed, with 
its forked end and connexion with the interambulacra, has the 
appearance of representing an entire ambulacral arch. The rotula is 
certainly a single and unpaired element, it arises as a single rudi- 
ment, and sections through it show no trace of suture, while the 
calcite which forms its skeleton is optically a single crystal. Its 
position in the radius corresponds to that of the rudiment of the 
tooth in the interradius, and it braces together the pyramids in 
much the same fashion as the odontophore links the jaws of star-fishes. 
Can there have been ten unpaired elements in the mouth of the 
ancestral Asteroid ? 

A later stage of development than that represented by the young 
Gomocidaris is furnished by a young example of Strongylocentrotus 
drebakensis, O. F. M., the mouth-parts of which have also been 
illustrated and described by Lovén. In this, as Lovén points out, 
the hemipyramids have not yet become closely approximated in 
the radial plane, and consequently the interpyramidal muscles are 
of considerable length. The epiphyses, as seen from within the 
test, have acquired an interradial position, those of adjacent 
ambulacra meeting along an interradius. This is the arrangement 
of the parts in an Asteroid carried to an extreme. 

The lantern of Aristotle is at present in existing urchins dis- 
tinguished by its great relative height, but if it originated from 
ambulacral ossicles it must have been primitively far more depressed. 
The upward growth, which we imagine to have taken place, finds 
an exact parallel in the case of brittle-stars and star-fishes, the jaws 
in both of these groups being extremely depressed in fossil forms 
of Lower Ludlow age: indeed, it would not be far from the truth 
to affirm that, as the thickness of the jaws in recent Ophiuroids is 
to that of Silurian forms, so is the height of the modern lantern of 
Aristotle to that of Palwodiscus. The proportion is not exact, but 
nearly so. The rotule in Paleodiscus lie at about the level of the 
inner ambulacral series. 

The severance of the lantern from the plates of the test is an 
Q.J.G.8. No. 220, OA 


714 PROF. W. J. SOLLAS ON SILURIAN [Nov. 1899, 


interesting feature not met with in modern star-fishes or Ophiuroids : 
it is closely paralleled, however, in the Ophiocistia. Unfortunately 
we know very little of the anatomy of the buccal armature of this 
group, but that it was practically free from the remainder of the test 
seems to be demonstrated by the specimens of Huthemon and 
Eucladia in the Oxford University Museum. 

Summarizing the foregoing conclusions, I regard the lantern of 
Aristotle as homoplastic oh the buccal armature of star-fishes ; the 
pyramids are the modified first adambulacral plates ; the epiphyses 
have arisen from the first ambulacral plates cf the Echinoid series ; 
and the teeth represent the odontophore, which has acquired a 
persistent root; the radius and rotula remain problematical. 


The enquiry into which the characters of Palwodiscus have led 
us may be fitly concluded by an endeavour to picture to ourselves 
the manner in which a transition may have been effected from the 
Asteroid to the Echinoid type. The divergence probably commenced 
with change of character in the buccal apparatus. As this became 
increasingly efficient in the urchin, as compared with the star- 
fish, so did the power of obtaining food: in correlation with the 
increased alimentation stand the greater size of the body and the 
length of the large coiled intestine. With the development of the 
body, the incorporation of the arms was associated: by no means 
an unique phenomenon, since other instances are presented, by 
Astrophiura among modern Ophiuroids, and by the Ophiocistia among 
their extinct representatives as well as by some star-fishes. On the 
final absorption of the arms there would be left an apical region 
devoid of ambulacra, near which these organs would terminate ; 
the position of the anus might readily fluctuate with the growth of 
the intestine, and the madreporite would also be subject to wander- 
ings as the body underwent changes in size and form. In Kchino- 
cystis we meet with an organism very similar to that which hypo- 
thesis would lead us to expect: the ends of the ambulacra, the 
madreporite and the anus, instead of being associated as in regular 
urchins, are here free and independent. The apical disc has not 
yet appeared, but may well have arisen, at least in part, from the 
valvular plates of the anal pyramid, as Dr. Gregory has already 
suggested. 

Whether Echinoids be direct descendants of Asteroids or not, 
there can be little doubt that the two groups are closely connected. 
Their most distinctive common mark is the possession of tube-feet. 
and there would be considerable convenience in uniting them and 
their extinct predecessors into a single group, which might be 
termed the Helkopoda. Brittle-stars, which appear to have 
diverged from star-fishes at about the same time as Echinoids, retain 
greater primitiveness of character, but have become highly specialized 
in their mode of progression: the extinct and existing forms might 
be united under a new name, though less inconvenience will probably 
result from retaining the term Ophiuroidea and extending its 
meaning. Both Helkopoda and Ophiuroidea are strongly con- 


Vol. 55.] ECHINOIDEA AND OPHIUROIDEA. 715 


trasted with the so-called Pelmatozoa, not so much by their 
power of locomotion, for Antedon is a swift wanderer, as by the 
character of their buccal armature and the absolute difference in 
their method of obtaining nourishment. The Pelmatozoa obtain 
their food as it were in molecules, by ciliary action; the other 
Echinodermata ingest it in larger masses by a prehensile mouth or 
jaws. A name is greatly needed to distinguish the Apelmatozoa, 
and Megophagi might prove useful: it is physiological no doubt, 
but it rests on a morphological character. If these suggestions were 
to be adopted, our classification would stand thus :— 


ECHINODERMATA. 


MicrorHaci or PELMATOZOA. 


Amphoralia. 
» Cystoidea. 
Blastoidea. 
Crinoidea. 
Agelocrinida. 


Mucoruaai (characterized by a buccal armature or prehensile 
mouth). 


Monorcuipa (without a buccal armature). 
Holothuroidea. 


PentorcHipa (with a buccal armature). 


Helkopoda (possessing adhesive tube-feet). 


Asteroidea. 
Echinoidea. 


Ophiuroidea (characterized by muscular arms). 


Aes 


716 PROF. W. J. SOLLAS ON SPONGE-SPICULES IN THE [ Nov. 1899, 


38. On the OcctRRENCE of SPoNGE-sPICULES in the CARBONIFEROUS 
Limestone of DersysHire. By Prof. W. J. Sotzas, M.A., D.Sc., 
LL.D., F.B.S., F.G.8. (Read April 12th, 1899.) 


Arrrr the reading of a paper ‘On the Geology of the Ashbourne 
& Buxton Railway,’’ by Mr. H. H. Arnold-Bemrose, I ventured in 
the discussion that followed to suggest doubtfully the presence of 
sponge-spicules in one of the slices of Carboniferous Limestone that 
were exhibited in illustration of the subject on that occasion. As 
I had then opportunity for only a hasty glance through the micro- 
scope, I was not able to speak with much assurance; but through 
the kindness of Mr. Arnold-Bemrose I have since been able to give 
a more careful study to his preparations, and can now positively 
affirm what I before merely suggested. The remains: of sponge- 
spicules are fairly abundant in a rock-slice taken from a specimen 
obtained at Tissington cutting ; they present themselves as sections 
cut in various directions, longitudinal, transverse, and oblique, 
through long cylindrical rods, the terminations of which are obscure 
and indefinite : in rare instances the rod exhibits a marked expansion 
at one end, but does not assume a form that would enable us to 
refer it to any recognized order of the sponges. The greatest length 
observed for these spicules is 1°55 mm., the greatest diameter is 
0-08 mm., and the least diameter is 0:027 mm. When complete they 
were doubtless larger, but in any case they are far from approaching 
the comparatively colossal dimensions of the spicules of Hyalostelia, 
and rather recall such forms as have been identified by Dr. Hinde, 
‘I fear on insufficient grounds, with those of the existing genus 
Awinella.? The fossilspecies of the so-called Awiella occur in the 
Carboniferous Limestone of Clitheroe (Lancashire). 

The spicules were doubtless originally siliceous ; they are now 
completely transformed into carbonate of lime. The replacement 
has taken place ina very characteristic fashion ; the first stage in the 
process is not represented in this case: for an example we may turn 
to Hyalostelia Smithii, in the spicules of which, particularly in in- 
stances from the Carboniferous Limestone of South-westernu Scotland, 
a rhombohedral pitting extends from all over the surface deep into 
the substance of these bodies; each pit is occupied by a crystal of 
calcite, which has completed its growth within the spicule as freely 
as outside it. The calcite, indeed, appears to have exercised a 
corrosive action on the spicule. Nothing of the kind is observed 
when a spicule is dissolved in caustic potash or hydrofluoric acid ; it 
then melts away uniformly, or only yields more readily along the 
axial canal and between the concentric coatings. The effect in the 
case before us appears to be directly connected with the growth of 
a crystalline solid. In commenting on the preponderant growth 
which frequently occurs at the edges and corners of crystals, I have 
suggested that this is readily explicable by a principle which may 


1 Quart. Journ. Geol. Soe. vol. lv (1899) p. 237. 
? Monogr. Palzont. Soc. ‘ Brit. Foss. Spong.’ pt. 11 (1888) p. 145. 


Wolves. | CARBONIFEROUS LIMESTONE OF DERBYSHIRE. rely 


be loosely termed the ‘surface-tension’ of solids. An alternative 
explanation rests on the undoubted fact that over these regions 
molecular bombardment must attain a maximum ; butin the present 
ease this explanation is excluded, since at the surface where the 
growing rhombohedron of calcite meets the solid substance of the 
sponge-spicule such a bombardment will most probably be at a 
minimum. It seems to me possible that the excavation of the 
spicule stands in close connexion with the pressure exerted upon it 
by the growing crystals of calcite, where these are in apposition. 

However this may be, the final result of the corrosion by calcite 
is to replace entirely the opal of which the spicule originally con- 
sisted, and to replace it by a congeries of minute crystals of calcite. 
Since these crystals may, and generally do, commence their growth 
outside the limits of the spicule, the resulting pseudomorph rarely 
preserves the regular outlines which characterized its antecedent 
state, but exchanges this for a rough and jagged surface, almost 
precisely like that of a stick of sugar-candy. 

The spicules in the slice that I have examined from Mr. Arnold- 
Bemrose’s collection are in this state, and were it not for the fact that 
the crystals of calcite are very minute, and frequently bounded by 
impurities in the limestone, their individuality could only be traced 
doubtfully ; owing to these fortunate circumstances, however, they 
are as clearly defined as corresponding structures from the Chalk. It 
may be hoped, now that attention has been called to their occurrence, 
that further examples of these spicules may be obtained which may 
throw some light on their nearer affinities. In insoluble residues 
of the limestone, after treatment with acid, the occurrence of either 
remnants of sponge-spicules or minute crystals of quartz may be 
predicted.’ 

A physical or chemical explanation of the replacement of the 
comparatively insoluble opal of siliceous organisms by carbonate of 
lime has not yet been suggested, and seems as remote as when Zittel 
and myself first demonstrated its occurrence more than twenty years 
ago. 


Discussion. 


Dr. G. J. Hinpe said that some time since, with the permission 
of Mr. Arnold-Bemrose, he examined the identical microscopic 
section of limestone (No. 809) from the Tissington cutting referred 
to by the Author, but failed to recognize any sponge-spicules in it; 
and even now he (the speaker) did not feel convinced that the 
fragments of rods shown in the slide were sponge-spicules, while 
the calcite-bodies with circular outlines appeared to belong to 
Calesphera. The solitary siliceous fragment obtained by dissolving 
some of the limestone was probably a portion of a spicule. 

Dr. Hicks also spoke, and the AvurHor replied. 


) [Since this was written a small fragment of limestone, kindly given to me 
by Mr. Arnold-Bemrose, has been treated with acid, and in the insoluble 
residue several fragments of siliceous spicules have been found which agree in 
form and dimensions with those in the thin slice. ] 


718 MR. F, R. 0. REED ON THE LOWER PALHOZOIC [Nov. 1899, 


39. The Lower Patzozo1c Bepprep Rocks of County WATERFORD. 
By F. R. Cowrzr Reep, Esq., M.A., F.G.S. (Read May 10th, 
1899.) 

[Prater XLIX.| 


ConTENTS. Page 
I. Introductory Remarks’ ...c..cuccscknsues onaoemrs noeneeaceee eee 718 
Ik; Weseription Of the Hxposumes, 45.3. --5.4.cee scene renee meena 721 
(a) Raheen and Newtown Head. 
(6) Tramore Bay. 
(c) Garrarus and Kilfarrasy. 
(d) Annestown and Dunabrattin. 
(¢) Knockmahon. 
(f) Ballydouane Bay. 
(g) Killelton Cove to Ballyvoyle. 
III. General Succession and Subdivision of the Strata ............ 740 
LV. Paleontological Notes enicce-t ener cenese eee shoe ee eeen ae 741 


V. Petrological Notes on the Contemporaneous Volcanic Rocks. 763 
VI. Correlation of the Rocks of the Waterford Coast with those 

of other sAneas: ose. c0 tn ene. ne euee coe cle ct ae te eee 766 

WE, WCOMCIUSTON Wg alin cron eee se eee Ge eee eee 770 


I. Lyrropuctory REMARKS. 


THE principal exposures of the Lower Palzeozoic and associated rocks 
are found in the sea-cliffs which extend for nearly 20 miles westward 
from Tramore to Ballyvoyle Head, and along the banks of the Suir 
near Passage. Inland the outcrops are much obscured by Drift, 
and consequently the best opportunity of determining the succession, 
ete. is afforded by the coast-sections, which will therefore be here 
described. The complexity of many of these sections is con- 
siderable, and is mainly caused by the intrusion of various later 
igneous rocks, as Sir A. Geikie has remarked." 


Historical Summary. 


The earliest geological account of the region was published by 
Thomas Weaver” in 1821, in his paper on the ‘Geological Relations 
of the East of Ireland, but no details were given. 

In 1824 the Rev. R. H. Ryland’s ‘ History, Topography, & 
Antiquities of the County & City of Waterford’ appeared, in which 
we find many references to the rocks and mines (pp. 255, 258, 273). 

The paper by J. Hodgson Holdsworth * in 1833 on the ‘ Geology 
of the District of the Knockmahon Mines’ is specially interesting 
from its record of the discovery of fossils in the ‘ slate-rock’ near 
Knockmahon. 

In 1837 Weaver * published a paper on the ‘ Geological Relations 
of the South of Ireland,” in which he gave an account of the 


1 « Ancient Volcanoes of Great Britain,’ vol. i (1897) p. 247, 
2 Trans. Geol. Soc. vol. v (1821) pp. 117, 248, 251. 
3 Journ. Geol. Soc. Dubl. vol. i (1833) p. 85. 

4 Trans. Geol. Soc. ser, 2, vol. v, pt. i (1837) p. 1. 


ut ig 4 


Vols 55. | BEDDED ROCKS OF COUNTY WATERFORD. 719 


‘Transition rocks,’ enumerating the different lithological varieties 
and mentioning the occurrence of fossils in a cliff east of the 
Bonmahon river and also inland. 

Sir R. Griffith’ mentioned the ‘ Transition’ beds of this area in 
a paper in 1839, and in the same year Major Austin * described the 
‘Geology round the Shores of Waterford Haven.’ 

A paper by T. Austin ’ in 1841 dealt with the ‘ Elevation of Land 
on the Shores of Waterford Haven,’ and J. Apjohn*in the same 
year referred to the district in his Presidential Address to the 
Geological Society of Dublin. 

Some of the fossils from the Ordovician beds on the coast were 
described by Portlock’ in 1843, and in 1844 Sir R. Griffith ° 
mentioned the area in a communication to the British Association 
entitled ‘Certain Silurian Districts of Ireland.’ A fuller list of 
fossils from the beds near Tramore was given by H. N. Nevins’ 
during the same year, and in another paper® certain localities 
at which ‘Silurian’ fossils had been found in Waterford and 
the adjoining counties were mentioned. Sir R. Griffith’ in the 
following year discussed ‘The Order of Succession of the Strata 
of the South of Ireland,’ and referred the ‘schistose strata’ of 
County Waterford to the Lower Silurian. A few of the Waterford 
fossils were mentioned or described by M‘Coy* in his Synopsis 
published in 1846. 

The fullest and most detailed account which had so far appeared 
on the geology of the county was published by J. Beete Jukes " in 
1852, entitled ‘Sketch of the Geology of the County of Waterford.’ 
In this there is a description of the varieties of igneous rocks, some 
of which were noticed to be interstratified with fossiliferous sedi- 
ments. ‘The relations of the ‘ Silurian’ and Devonian beds are also 
discussed, and the movements which have affected the district. 
The fossiliferous limestones at Quillia and Tramore are considered 
to lie on different horizons, the lowest being at Quillia. 

There is a brief account of the older rocks of County Waterford 
in Murchison’s ‘ Siluria’ (1st ed. 1854, p. 166). The papers by 
J. Kelly * on the Paleozoic rocks of Ireland express the view that 
the Waterford beds may be compared with the Bala Series of 
England, and a list of fossiliferous localities in the county is 
given. An important paper by Jukes & Haughton,” entitled 
‘The Lower Paleozoic Rocks of the South-east of Ireland,’ was 


1 Journ. Geol. Soe. Dubl. vol. ii (1839) p. 78. 

2 Proc. Geol. Soe. vol. iii (1839) p. 154. 

3 Tbid. (1841) p. 360. 

* Journ. Geol. Soc. Dubl. vol, ii (1841) p. 132. 

° ‘Rep. Geol. Londond.’ 1843, pp. 262, 283, 292, ete. 

© Rep. Brit. Assoc. Trans. (York) p. 46. 

7 Journ, Geol. Soc. Dubl. vol. iii (1844) p. 78. © hid. poor. 
® Ibid. p. 150. 10 «Syn. Silur. Foss. Irel.’ pp. 7, 16, 26, ete. 
1 Jour:. Geol. Soc. Dubl. vol. v (1852) p. 147. 

22 T[bid. vol. vii (1856) p. 115; ded. vol. viii (1860) p. 251. 

13 Trans. Roy. Irish Acad. vol, xxiii (1809) p. 563. 


720 MR. F. B.C. REED ON THE LOWER PALZOZOIC [Nov. 1899, 


published in 1859. In it there are short lists of fossils from the 
so-called ‘Cambro-Silurian,’ and particular attention is paid to the 
igneous rocks. 

Some general remarks on the succession of the rocks along the 
coast from Dungarvan to Annestown are found in a paper by 
W. B. Brownrigg & Theo. Cooke.’ 

The publication of the Geological Survey Memoir in 1865, in 
explanation of Sheets 167, 168, 178, & 179, marks an important 
advance in our detailed knowledge of the area. The care and 
accuracy with which the work was done in the face of great 
difficulties can be fully appreciated only by one who knows the 
country intimately. After the publication of this memoir no work 
of importance was done for many years on the older rocks. Some 
of the graptolites were described by W. H. Baily? in 1869, and 
there is a brief account of the general geology in G. H. Kinahan’s 
“Geology of Ireland, published in 1878 (p. 27). Prof. Lapworth * 
referred to the occurrence of certain species of graptolites in County 
Waterford in his paper on the ‘ Distribution of the Rhabdophora,’ 
The petrological characters of some of the igneous rocks were 
described by Dr. Hatch* in 1889, and in 1891 Sir A. Geikie’ gave 
a brief account of the vulcanicity of the area in his Presidential 
Address to the Geological Society. Messrs. McHenry & Watts’s 
“Guide to the Collection of Rocks & Fossils belonging to the 
Geological Survey of Ireland,’ issued in 1895, summed up (pp. 82, 
89, 90) our knowledge of the geology of the county. Sir A. Geikie,” 
in his great work on voleanic action in the British Isles, described 
in general terms the igneous rocks of Waterford and directed 


special attention to the prevalence of intrusions and to the complex 


of-voleanic vents. 

Three papers‘ on questions relating to the structure, stratigraphy, 
and paleontology of parts of the district have been contributed by 
the present author. 


Scheme of Treatment. 


In this paper the bedded rocks, both sedimentary and volcanic, as 
displayed on the coast will alone be dealt with. The intrusive 
rocks will be described on another occasion. In order to present 
the evidence clearly, it will be convenient here to consider the 
exposures separately, and they will consequently be described in 
the following order: (a) Raheen and Newtown Head; (6) Tramore 
Bay; (¢) Garrarus and Kilfarrasy ; (d) Annestown and Duna- 
brattin; (e) Knockmahon; (f) Ballydouane Bay; (g) Kuillelton 
Cove to Ballyvoyle. 


1 Journ. Geol. Soc. Dubl. vol. ix (1860) p. 8. 

2 Quart. Journ. Geol. Soc. vol. xxv (1869) p. 158. 

’ Ann. Mag. Nat. Hist. ser. 5, vol. iv (1879) p. 424. 

4 Geol. Mag. 1889, p. 545. 

5 Quart. Journ. Geol. Soc. vol. xlvii (1891) Pres. Addr. Proe. p. 155. 

6 « Ancient Volcanoes of Great Britain,’ vol. i (1897) pp. 242-250. 

7 Geol. Mag. 1895, p. 49; Quart. Journ. Geol. Soc. vol. liii (1897) p. 269; 
Geol. Mag. 1897, p. 502. 


a me et lie lt tr sea nate: te gh di GN eee te aS 


————————————— 


Nok 55. | BEDDED ROCKS OF COUNTY WATERFORD. 721 


IJ. Descrrrtion oF THE EXPOSURES. 


(a) Raheen and Newtown Head. 


It is along this strip of coast just north of Newtown Head, near 
the mouth of the River Suir, that is seen the most distinct and 
extensive section of the contemporaneous igneous rocks regularly 
interstratified with the fossiliferous beds (fig. 1, p. 722). The 
succession is traceable in a comparatively undisturbed series of 
beds for a distance of nearly amile along the shore. The exposure 
begins on the foreshore a few hundred yards north of Raheen Bridge, 
below the old Geneva Barracks. The cliffs themselves are here 
composed of Boulder Clay, but on the beach, and particularly at 
low water, are found reefs of rocks consisting of olive-coloured or 
greyish mudstones, mostly without good cleavage, and either 
breaking with a subconchoidal fracture or splintering into angular 
fragments. Sandy seams from 3 to 6 inches thick are occasion- 
ally interstratified with the mudstones, and the lower beds contain 
black carbonaceous patches. The total thickness of these mudstones 
is unknown, but they are exposed for fully 300 yards along the coast. 
Their general dip is towards the line of cliffs, at angles of from 45°” 
to 60° north-west. Numerous small faults traverse them, and 
their strike is in places distorted for a short distance. An interesting 
example of a small volcanic neck occurs in them about 150 yards 
north of Raheen stream. 

Dipping below these mudstones a short distance north of this 
stream are found hard, compact, black slaty mudstones breaking 
up into irregular cubical fragments or splintering with a subcon- 
choidal fracture. These beds, which are traversed by several small 
faults, do not measure more than 12 feet in thickness, and beneath 
them come greenish-grey, thin-bedded, ashy sandstones, with black 
shaly fragments, exposed on the reefs opposite Raheen stream. The 
individual beds are from 6 to 12 inches thick, and the thickness 
of the whole series amounts to about 30 feet with a north- 
westerly dip of 45° to 55°. The next bed in descending order 
is a tough grey felsite [6 w]! about 6 feet thick, scarcely separable 
from an underlying peculiar perlitic felsite into which it imper- 
ceptibly passes. This perlitic felsite [7 w], which is fully described 
on p. 763, shows its structure very distinctly on the white weathered 
surface and forms a conspicuous rib of rock on the beach, about 
35 feet thick, with a dip of 45° north-westward. Beneath it is a 
bed of coarse volcanic breccia, 10 feet thick, composed of subangular 
and rounded fragments of felsites and slates. Then comes a series 
of thin-bedded fissile greenish ashes with a thickness of 70 to 
80 feet, and resting on dark greenish and black sandy mudstones 
with a slight unconformity, for the line of junction is somewhat 
irregular, and the lowest layers of the ashes contain rounded masses 
and pebbles of the mudstones pointing apparently to contem- 
poraneous erosion. The mudstones are about 40 feet thick, and 


+ The numbers in brackets refer to slides in my collection. 


“A Ul 
[4 QT] sey1sToy poppeq jo sseum pepupouy = AA 


[4 QT] ogtspoy oatsnaqut Loa8 Td=A 


"3293 0G 01 OZ ‘(4 GT] A avon Las04 
puv poeysno ‘soqispoy oatssuut Aors-ysintg = a 


"709J Q ‘opspof cepnpou Aors-yaeq = J, 


"F995 OG 
[Zoe] eqstey Ayu foa8 - yslteatin = g 


y003 § ‘[“ FT] OFSTOF IeTNpoNT = 


39°F 06 ‘[TO¢] 
[“ eT] oqisjey ystucer$ ayed oalssuy = & 


999f GT 
°4 OL ‘[eo9] Hn9 ontspay £ox8 yordu0g = g 
"992 (9 ‘stodv] Suryeuseyye 
ur sya pae [goa] [eo¢] sensieq = oO 


"3225 GT ‘LZ09] eye1eu0]38e dIUBIIOA = N 


"(4205 ZL) Syny esavog = PL 


"(4903 OT) o7e10M0188e olUvd[OA = 'T 
"(qe27 OG) BN Jo spueq q7IM ‘sepispoy Kong = yy 


eer Gr 
s}loyo peppeq - uly, = ¢ 


"(q00} F) OUspoy = T 


‘Loo¢e] [109] 


400} OF ‘(soTeyg usay 
ey) souoyspnur Apuvs SNOOJI[ISSOY = TT 


"(929 08 
07.04) S49 Ystuse49 opssy poppaq-uiyy, = 49 
"(900} OL) eyetour0[83e oruvojOA = WT 
"2025 GE ‘[4 1] opsyoy ortpted houg = x 
"y02f 9 ‘Lm Q] oytsqey Lord ySnoq, = a 

*(490F QE) seu0ys 

-pues Ayse poppeq-urqy fo.15-ysiuee1g = 9 
‘(q@0} GT) souojspnut Ayys youg = g 

‘saves Apurs 
UIT} YIia So7e[s pue seuUo}spnu UEDA = 


[99°7 06 =Yout T : eyvos eyeurrxoadd y | 


"Pray Unoimarr fo aps yps0w ay2 uo asoysosof ay) LO wonros or» nUuunibog —T “SLT 


Vol. 55.] LOWER PALHOZOIC ROCKS OF COUNTY WATERFORD. 723 


dip at 45° north-westward. 


It is from these beds that the organic 


remains were obtained which were described by Portlock and 
others ' from the locality called Newtown Head. 
Salter * describes the following trilobites from these beds :— 


Acidaspis Jamesii, Salt. 
Amphion benevolens, Salt. 
Ampyx mammillatus, Sars. 
Barrandia Portlockii, Salt. 


Trinucleus seticornis, His. ( = hiberni- 
cus, Reed). 
Salteria involuta, Salt. 


Davidson * mentions the following brachiopods :— 


Lingula ovata, M‘Coy. 
brevis, Portl. 


Crania divaricata, M‘Coy. 
Strophomena corrugatella, Davy. 


In the Dublin Museum of Science & Art are the Geological 
Survey collections, and I have had the privilege of examining them, 
with the result of identifying the following species from Newtown 
Head. Those marked with an asterisk have been collected also by 
me from these beds. 


Orthis calliigramma, Dalm. 
Piectambomtes quinqguecostata, M‘Ooy. 
Lingula brevis, Portl. 
Orbiculoidea oblongata, Portl. 
Pholidops ? balcletchiensis, Dav. 
Ctenodonta sp. 
Bellerophon perturbatus, Sow. 
Pleurotomaria sp. ? 
Orthoceras gracile, Portl. 
- sp. 
Bijolkihes ef. striatus, Hichw. 
Echinosphera granulata, M‘Coy ? 
x Giyptocystis ct. pennigera, Hichw. 
Dicellograptus sp. 
Didymograptus sp. 


Acidaspis Jamesii, M‘Ooy. 
*Ampyx mammillatus, Sars. 
costatus, Sars. 

* Asaphus sp. 

Calymene duplicata, Murch. 
* Cybele cf. bellatula, Dalm. ? 
ef. rex, Nieszk. 
McHenryi, sp. nov. 

Harpes Flanagant, Port. 
*Lichas laxatus, M‘Coy ? 

Barrandia Portlockii, Salt. 

Spherexochus nurus, Beyr. 
* Trinucleus hibernicus, Reed. 

Turrilepas scotica, Nich. & Eth. 

Orthis argentea, His. 


The commonest fossils occurring here are Ampyxw mammillatus, 
Orthis argentea, and Trinucleus hibernicus. The beds do not seem 
divisible into zones, the same general facies occurring throughout, 
but the exposure has been too limited on the occasions of my visits 
to collect with the idea of zonal subdivision. 

A wedge of very decomposed felsite, some 4 to 5 feet wide, is 
exposed close under the elifts, running into these fossiliferous beds 
near their base. At the base of the mudstones are found thin- 
bedded cherts [601] [500] 12 feet thick, and below them come grey 
felsites and ashes in alternating layers, amounting in all to about 
30 feet, with the usual strike and dip. Underlying them is a 
coarse volcanic agglomerate composed of large rounded or subangular 
lumps and small angular fragments of various felsites, slates, 
mudstones, and sandstones, with a thickness of 10 feet. Beneath 
this are coarse ashes 12 feet thick, resting on an agglomerate [602] 
containing rounded or subangular fragments of pinkish felsites, 
varying from small chips to pieces 6 inches or more in diameter, 


1 Portlock, ‘Rep. Geol. Londond.’ 1843, pp. 262, 283, etc. ; M‘Coy, ‘Syn. Sil. 
Foss. Irel.’ 1846, pp. 7, 16, 26, ete. 

2 Mem. Geol. Surv. dec. ii, vii & xi; Monogr. Paleont. Soc. ‘Brit. Trilob.’ 
pp. 82 & 140. 

3 Monogr. Palzont. Soc. ‘ Brit, Silur, Brach.’ vol. iii, pp. 38, 50, 78, ete. 


724 MR. F. R. 0, REED ON THE LOWER PALZOZOIC [Nov. 1899, 
embedded in a greenish matrix with broken crystals of felspar, 
etc. The bed averages 15 feet in thickness. 

At this point masses of shingle and seaweed hide much of the 
outcrop of the beds, but below the agglomerate a series of alter- 
nating felsites [503] [568] and greenish thin-bedded ashes, 60 feet 
or so thick, can be traced. | 

An angular rib of a compact greyish felsitic rock [605] with a 
thickness of 10 to 12 feet stands up here on the beach, and under 
the microscope is seen to consist of an agglomeration of fragments 
of highly vesicular lava in a finer pumiceous matrix. A pale 
greenish, massive, well-jointed felsite [13 w] [501], 20 feet thick, 
occurs below, and then a thin band of nodular felsite [14 wj 3 feet 
thick. Beneath this is a greenish-grey flinty felsite [502] 50 feet 
or so thick, and another nodular felsite of a darker colour, 
6 feet thick. 

Bedded bluish-grey massive felsites [15 w] amounting to a 
thickness of 20 to 30 feet, in places crushed, and with a few 
fragmental beds near their base, follow next in descending order 
with the usual dip; and we then meet with several tongues and 
irregular veins of a pale grey intrusive felsite [16 w] irregularly 
cutting across the strike of the felsites for a distance of 160 feet or 
more at the base of the cliffs. This felsite, which is of a type en- 
tirely different from those of the bedded series, has been intruded into 
the latter, rendering them horny and fissile, and strips of them 
occur between the intrusive tongues. One of these included masses 
measures 10 feet across, and forwale of dark greenish massive 
felsites [18 w], some of which are nodular with intercalated tuff- 
bands. Beyond this intrusion bedded felsites, occasionally nodular, 
and thin-bedded ashes again set in to a thickness of about 40 feet. 
An intrusive tongue of fine-grained dark grey felsite [20 w], very 
similar to that just mentioned, is then met with, having a width 
of 30 to 40 feet near the cliffs, but thinning seaward. A crush- 
zone, 1 foot thick, is found cn its northern margin. Beyond it are 
bedded, grey, compact, horny felsites [21 w], with some thin nodular 
bands [22 w] intercalated; they are crushed and altered where in 
contact with the intrusive rocks, and do not amount to more than 
30 feet in thickness. A mass of intrusive rocks, felsites [606], 
etc. extends from them for some 300 feet or more along the 
shore, showing signs of crushing on its margin, and apparently 
consisting of several more or less distinct intrusions, differing slightly 
in colour and texture. Parts of it contain numerous xenoliths, and 
are scarcely distinguishable from a fine ash. As we approach 
nearer to the northernmost point of Newtown Head it [606] includes 
several large masses and blocks of the bedded felsites [44 w] 
and greenish ashes, some of them still preserving their bedding- 
planes. There are no signs of bedding in the intrusives. 

At the northernmost point of Newtown Head a green diabase 
[607] sets in; it is penetrated by veins of a rock very similar to 
the felsite (606), but the smaller veins of it and the margins of the 
larger tongues are highly vesicular. 


Vol. 55.] BEDDED ROCKS OF COUNTY WATERFORD. 125 


The section now increases in. complication, and we meet with 
bedded fine felsitic tuffs [611] [610] dipping into the cliff at angles 
from 45° to 60°, and associated in an intricate manner with the 
intrusions of diabase [607] and greyish felsite [606]. On the 
south side of a projecting spur fine-bedded greenish felsitic tuffs [610 | 
are seen, containing many vesicular fragments, and with occasional 
interbedded bands of darker tuff [611] passing into a patch of 
coarse agglomerate at the base of the cliff. These beds dip at 
about 60° into the cliff, and are traversed by numerous small faults 
and thrusts. A bluish-grey rotten intrusive rock of doubtful nature 
[608] [517], with vesicular margins and showing conspicuous 
spheroidal jointing with concentric shells, cuts across them and 
covers nearly all the foreshore, but on the south side of this mass 
the tuffs with thin-bedded felsites are again traceable, dipping into 
the cliffs at 45°. One of these felsites [609], which thickens out at 
the expense of the tuffs, is dark green and contains porphyritic 
felspars. Following the cliffs southward we find small veins 
of a new type of felsite piercing the bedded rocks and entangled 
with them. These small veins, in a distance of about 100 or 
150 feet, swell out into massive sheets of a bluish-grey flinty felsite 
which belongs to a later outburst of volcanic activity, and with 
the complex group of intrusions of diabases, felsites, etc., dis- 
played on the south side of Newtown Head, brings the cliff- 

sections here to a close at the northern end of Woodstown Strand. 


In the small cove below Ballyglan House, on the north side of 
Knockaveelish Head, the 
cliffs are made up of _. 
soft black slates, greenish Fig. 2.—Ground-plan of disturbed beds 
mudstones, and thin on the foreshore near Tramore. 
flags dipping mostly at 
70° north-westward, but 
in places much crushed 
and disturbed, and at the 
southern end folded over 
in a gentle anticline. 
Though in Sheet 179 of 
the Geological Survey 4 Za 
map this locality is ee LE 
marked with an asterisk, ee ess ae 
I have myself been un- panieae s 7 of oe [112 we 

1 =I1mpure lmestones ramore limestone 

oe Ms scale ios Pee rb ee nes ay locally crushed : 
the Survey Collections. O=Black ei a enehs aeaiod and appearing 
The age of these beds as irregular tongues in the limestones. 
must therefore remain D=Intrusive vein of felsitic glass (110 w] [33]. 
doubtful for the present. A few yards east of this locality similar veins 


pierce the slates, and are inyolved in their 
The Old Red Sandstone crushing and crumpling. 
Conglomerate rests upon [See p. 726.] 


them unconformably. 


726 MR. F. R. C. REED ON THE LOWER PALA0ZOIC [Nov. 1899, 


(b) Tramore Bay. 


Along the west side of this bay the strike of the beds and trend 
of the coast nearly correspond. From Tramore village to Great 
Newtown Head the impure limestones, slates, etc., are almost 
continuously exposed.1_ Dark grey, more or less calcareous slates — 
conformably underlie the limestones, which dip at angles from 30° 
to 75°, and contain an abundant fauna. A thick sheet of diabase 
[59 w]is a conspicuous object in the cliffs, resting for the most 
part on the top of the limestones, but occasionally cutting across 
them. 

At the north-western corner of the bay the dark grey slates are 


Fig. 3.—Section in the cliff-face between Tramore and 
Doneraile Cove. 


Ny ih, 


BA WLM 
wii, iw BE gfe 
Aes Ve? aft, We iyflor 
Os i Lae 


ML. 
La Oe iene ee © en = 3) 


A=Drift and surface-soil. | D=Black slates, crushed along fault- 


B= Diabase. lanes. 
C=Zone of crushed and baked E=Sandy limestones (Tramore Lime- 
slates. stone Series). FF= Faults. 


much crumpled and crushed, and their relations are obscure. Small 
intrusive veins of felsitic glass [33] [110 w] penetrate the slates and 
limestones, but not the diabase. Tongues of black slate run into 
the limestones like intrusions, and several faults add to the con- 
fusion (figs. 2 & 3). But this zone of disturbance exists only near 
the junction of the slates with the limestones, as in the cliffs behind 
we find the latter undisturbed and generally in an almost vertical 


1 Geol. Mag. 1897, p. 502. 


Vol. 55-] BEDDED ROCKS OF COUNTY WATERFORD. 727 


position, with a strike from north-east to south-west ; while on the 
reefs at low water the slates alone 

are exposed, butina muchcrushed Fig. 4.—Ground-plan of the 
condition. The exceedingly com- foreshore near T'ramore (dis- 
plicated relation of the slates and tance = about 150 yards). 
limestones does not extend for 
more than 100 yards, and then 
the diabase [112 w] comes down 
and spreads out over the fore- 
shore, enclosing patches of the 
bedded rocks. Their relations are 
not, however, quite simple even 
here, for their line of junction 
is wavy and irregular, and along 
it they are occasionally crushed or 
shattered into a friction-breccia. 
There is no evidence that we 
are dealing with an unconformity 
due to contemporaneous denuda- 
tion and original conditions of 
deposition, but all the facts point to 
mechanical disturbance subsequent 
to the deposition and consolidation 


of the beds (fig. 4). A=Intrusive diabase [112 w]. 
In a small cove below Doneraile B=Impure limestones, dipping 
Walk occur (fig. 5, p. 728) thin into the cliffs at high angles 


: (Tramore Limestone Series). 
beds of fine black argillaceous C=Black slates, locally much A 


slates, ashy grits, and cherty beds, turbed and crushed (Tramore 
all very much baked and altered, a pet 
and resting on the diabase, which wes ee 
is seen tate intruded into their me > gh 
base. These beds have the same 
dip as the limestones which underlie the diabase (fig. 6, p. 728), and 
there is nothing to make us doubt that they are part of the same 
regular conformable series, and that they occur in their true order 
of succession. On the south side of this cove, and resting upon the 
fine black slates, etc.,is seen an intrusive sheet of peculiar grey 
altered diabase [66][10]{18][12], which separates them from 
some pale greenish bedded felsites. These appear to be contempo- 
raneous volcanic rocks, and to overlie regularly the sedimentary beds 
(fig. 7, p. 729). As the trend of the coast is just here across the 
strike of these beds, it is possible to trace the succession in the cliffs 
in spite of the interruptions due to snbsequent intrusions. These 
bedded felsites [13][80][54 w] are seen dipping at angles of 60° to 
70° into the cliffs, and thus agreeing with the above-mentioned 
sedimentary beds. The section shown in fig. 7 (p. 729) is seen in 
the face of one of the small projecting spurs of cliff. 

There is a thick irregular mass of greyish felsite [120] [58 w] 
intruded among the bedded felsites in the cliff as one approaches the 
steps down to the beach from Doneraile Walk, and at this place the 


728 MR. F. R. C, REED ON THE LOWER PALMOZOIC [Noy. 1899, 


felsites are thin-bedded, and have bands of black slate and calca- 
reous felsitic tuffs [644] [53 w] intercalated among them. These 
are exposed again atthe top of the cliffs. At this point a fault 
of not much importance occurs, with a downthrow to the north, 


Fig. 5.—Section in the cove below Doneraile Walk. 


vn ldtuan hy 


W 
4, “Hy 
“all WD 


Ly i 
vivi/ / 
/ | 


A=lIntrusive diabase. 

B=Bedded black shales, thin limestones, flags, cherts, ashy grits, ete. 
(Carrigaghalia Series). 

C=Sheet of grey altered diabase [66] [10]. TT=Small thrust-plane. 


Fig. 6.—Section in the cliff below Doneratle Walk. 


A = Diabase. 
B= Bedded sandy limestones (Tramore Limestone Series). 


shifting back westward the limestones and diabase, so that they 
reappear in the cliff-face on its south side. All the rocks in its 
vicinity are much disturbed and shattered, especially on the south 
side, and numerous smaller faults traverse them. 


Vol. 55. | BEDDED ROCKS OF COUNTY WATERFORD. 729 


About 50 yards south of this cove another fault cuts across the 
beds nearly at right angles to their strike, causing a horizontal 
displacement of all the beds of about 30 feet. The limestones from 
this point to Lady Elizabeth’s Cove form the cliffs, dipping at 
65° north-westward and resting conformabdly on the dark calcareous 
slates. A striking feature in the limestones is the occurrence of 


Fig. 7.—Section in the cliff, 40 yards north of Doneraile Cove. 


Myry 

by Pepuy 
wea) 

Te aye 4, Me, 


f 


li 


i 


f 
[{/ 


f  A=Bedded pale greenish felsites [13] [80]. 
B=Conspicuous band of felsite [54 w]. . 
BP fiinls bedded banded felsites and slate, (°° S80 
TT=Small tbhrust-plane. 


frequent nodular bands, composed principally of masses of Monti- 
culipora petropolitant. Other organic remains occur in places in 
some abundance. ‘The following species have been here collected, 
of which those found by me are marked R, and those in the Survey 


Collection labelled ‘ > , locality 20,’ are markel 8. :— 


S. Agnostus agnostiformis, 8S. Turrilepas cf. scotica, Nich. & 
M‘Coy. Kth. 
S. Asaphus Haughtoni, sp. nov. R. Orthis calligramma, Dalm. 
Ss. sp. R. 8. Orthisina (?) crispa, M‘Coy. 
S. Bronteus hibernicus, Portl. R. ef. sguamata, Pahl. 
R. Calymene Blumenbichi, var. R. Plectambonites sericea, Sow. 
Curactaci, Salt. R. 8. Rafinesquina deltoidea, Conr. 
R.S. brevicapitata, Portl. 8. exoansa, Sow. 
R. Cybele sp. 8S. Stropheodonta imbrex, Pand. 
8S. Llenus sp. S. Ptilodictya dichotoma, Portl.? 
R. 8. Phacops Jamesti, Portl. S. Conularia elongata, Portl. 
S. Remopleurides Portlocki, sp.nov. | R. Stenopora fibrosa, Goldf. 
S. Salteri, sp. nov. R. Monticulipora petropolitana, 
S. Beyrichia affins, Jones, Pand. 


Close to Lady Elizabeth’s Cove is the volcanic neck figured by 
Du Noyer in the Survey Memoir, fig. 5, p. 54. In the pathway 
between Doneraile Cove and Lady Elizabeth’s Cove occurs a series 
of thin beds of cherts [854] [52], tufts, felsites [626] [5671 [9], 

Q. J. G. 8. No, 220, 3B 


730 MR. F.R. C. REED ON THE LOWER PALMOZOIC [Nov. 1899, 


and altered slates, forming part of the bedded series resting on 
the limestones, as seen in the cliffs nearer Tramore. Sections of the 
cherty rocks reveal traces of radiolaria. Dr. G. J. Hinde, who has 
kindly examined the sections, is, however, unable to say definitely 
that radiolaria are present, though he admits the close resemblance 
of the rock to a radiolarian chert. 

Returning to the shore and south side of Lady Elizabeth’s Cove, 
we find that it is principally composed of the diabase-sheet, but in 
contact with it above is a small exposure of baked and altered black 
slates which, just at their junction with the diabase, contain grapto- 
lites. Some were collected here by the Survey officers in 1865, and 
are recorded in the Memoir in the list of fossils. They comprise 
the foilowing forms :— 


Callograptus Salteri, Hall. Dendrograptus sp.? 
Climacograptus bicornis, Hall. Didymograptus sp. 
ef. teretiusculus, His. Dicellograptus sp. 


Cenograptus gracilis, Hall. 


Recently I have myself collected the following’ at this spot :— 


Diplograptus foliaceus, Murch. | Dicellograptus sp. 
Cryptograptus tricornis, Carr. | 

A fault shifts the limestones seaward on the south side of this 
cove, and with the diabase-sheet they form the cliffs till we come 
to a small cove just north of the Ladies’ Bathing-cove opposite the 
rock of Carrigaghalia (fig. 8). In this cove the black graptolite- 


Fig. 8.—Section im cliffs of northern cove opposite Carrigaghalia. 


cid Waltdigintecy 
M] pee) SIVA 
hf) iil Avi 
| f > ul 
LR. iam 
BCs 


Oe TS 
Wes — ar eas 
Mi ae atak + 


y i) 
LHD b tpt en + 


ise SSS SS 


a —— 
wre ~~ SaaS Ss SS 


A=Intrusive sheet of greyish felsite [118 w}. 

B=Black shales with flaggy beds, baked near the contact with the intrusive 
rocks (Carrigaghalia Series). 

C=Impure fossiliferous limestones (Tramore Limestone Series). 

D=Coarse dark green diabase. 


shales dipping north-north-westward at 75° are found again, with 
the limestones dipping below them regularly, and with an intrusive 
felsitic sheet [118 w] piercing the former. A few thin, sandy tuff- 
bands [641] and crushed felsites are interbedded among these shales, 


1 Determined by Miss G. L. Elles, Newnham Coll. 


Vol. 55.] BEDDED ROCKS OF COUNTY WATERFORD. 731 


which closely resemble those in the cove under Doneraile Walk 
(fig. 5, p. 728). So far I have found only one graptolite—a Climaco- 
graptus—at this spot. 

The section previously given’ by me is now obscured. ‘The 
black shales in the Ladies’ Bathing-cove yielded the following 
graptolites :— 

Climacograptus perexcavatus, Lapw. Dicranograptus Nicholsoni, Hopk. 


Cryptoyraptus sp. ramosus, Hall. 
Dicellograptus sextans, Hall (?). 


Tongues of greyish felsite [4] [68] similar to that in the cove to 
the north penetrate the shales which also form all the upper part of 
the cliffs. 

It was presumably from some of these shales between Lady 
Elizabeth’s Cove and this spot that the graptolites mentioned by 
Prof. Lapworth ? from a list given by Baily * were obtained. ‘They 
comprise the following species, and are stated to have been found 
in ‘ dark shales in Tramore Bay ’ :— 


Climacograptus bicornis, Hall. Dicranograptus ramosus, Hall. 
Cenograptus gracilis, Hall. Didymograptus sp. 
Dicellograptus sextans, Hall. * | Diplograptus foliaceus, Murch. 


The graptolitic fauna mentioned above in the various collections is 
characteristic of the Dicranograptus-shales which in South Wales 
overlie the Llandeilo Limestone. 

South of the Ladies’ Bathing-cove the limestones are seen stretching 
along the coast and dipping westward or west-north-westward at 
angles varying from 45° to 60°, with the diabase-sheet running 
through them and other intrusions piercing them; and at Newtown 
Cove we find them at its mouth dipping at 45° north-westward. As 
we proceed up the glen they are seen to be overlain by some dark 
fossiliferous calcareous shales, and these pass up into very fossili- 
ferous calcareous shales and mudstones with beds of impure lime- 
stone, all of which are much weathered and are exposed for some 
50 yards at the side of the road running up the glen. A much- 
crushed sheet of diabase [628] is found near the top of the series, 
and above it come soft, dark, unfossiliferous concretionary shales 
breaking with an irregular fracture. Upon them rests another 
intrusive sheet, 40 feet thick, of dolerite [116] [629], and upon it a 
mass of greenish felsite [630] exposed for some 30 yards by the 
roadside. 

As the strike of the graptolitic shales of Lady Elizabeth’s and 
the neighbouring coves would bring them nearly to the mouth of 
Newtown Cove, there must be a fault between these points shifting 
them up the glen. The soft dark shales above the crushed diabase- 
sheet probably represent them. The limestones are more argillaceons, 
and the argillaceous graptolitic shales more calcareous. The diabase- 
sheet has almost thinned out. 


1 Geol. Mag. 1897, fig. 1, p. 507. 


2 Ann. Mag. Nat. Hist. ser. 5, vol. iv (1879) p. 424. 
% Quart. Journ. Geol. Soc. vol. xxv (1869) p. 158. 


38B2 


732 


MR. F. R. C. REED ON THE LOWER PALAOZOIC 


[ Nov. 1899, 


The following fossils have been collected here by me from the 


lower beds (top of Stage 2):— 


Calymene Blumenbachi var. Caractaci, 
Salter (?). 

—— brevicapitata, Portl. 

Cheirurus sp. 

Cybele sp. 

Enerinurus fallax, sp. nov. 

Harpes sp. ? 

Phacops Brongniarti, Portl. 

Jamesii, Portl. 

Remopleurides tuberculatus, sp. nov. 


Trinucleus concentricus, Eaton (?). 
Primitia mundula var. producta, 
Jones. 
Orthisina cf. sywamata, Pahl. 
(2) crispa, M‘Coy. 
Plectambonites quinquecostata, 3 
sericea, Sow. 
Echinosphera sp. 
Bolboporites sp. ? 


M‘Coy. 


From the upper beds (Stage 3) the following were collected :-— 


Agnostus agnostiformis, M‘Coy. 
Ampyx cf. Volborthi, Schmidt. 
mammniitllatus, Sars. 
Asaphus radiatus, Salt. (?). 
rectifrons, Portl. 


S sp. 

Bea Portlocki, Salt. 

Calymene Blumenbachi var. Caractact, 
Salt. (?). 

brevicapitata, Portl. 

—-s 

Gries gelasinosus, Portl. 

Cybele sp. 

Encrinurus fallax, sp. nov. 

Harpes Dorani, Porth. (?). 


sp. 

I ie Bailyi, Salt. 

—— Davisi var. pseudolimbatus nov. 
—— cf. Dalmani, Volb. 

Lichas hibernicus, Portl. (?). 
Megalaspis sp. y. 


Phacops Brongniarti, Portl. 
truncato-caudatus, Portl. 
Remopleurides Colbiz, Portl. 
dorsospinifer, Portl, 
laterispinifer, Portl. 

Salteri, sp. nov. 

tuberculatus, sp. NOV. 
Tramoria punctata, gen. et sp. nov. 
Trinucleus concentricus, Haton (?). 
hibernicus, Reed. 

Primitia strangulata, Salt. 
Beyrichia affinis, Jones. 

Turrilepas cf. scotica, Nich. & Eth. 
Orthis calligramma, Dalm. 

— 5s 

De te (2) crispa, M‘Coy. 
Plectambonites quinquecostata, M‘Coy. 
sericea, Sow. 

Helminthochiton sp. 

Glyptocystis sp. 


In the Geological Survey Collection at Dublin the following 
fossils from this locality are preserved, but the two stages were 
not distinguished, though frequently indicated by the lithological 


character of the specimen :— 


Stages. 
Agnostus agnostiformis, M‘Coy... 2, 3 
Asaphus rectifrons, Portl. ......... 3 
= Od See nciratpsirionl oe Ruielontoeaollees 2 
Ampyzx ct. Portlocki, Barr. ...... 3 
Barrandia Portlocki, Salt. ...... 3 
Calymene brevicapitata, Portl. De ie 
SP. iesee ea weeaee Come eee amemee Zor 3 
Cheirurus gelasinosus(Portl.), var. 2 
Cybele tramorensis, Reed ......... 2 
TUGOSE, APO oseenae once pas ue 2or 3 
sextuberculata, sp. NOV....... 2 or 3 
verrucosa, Dalm. (Ce eas oh 3 
Encrinurus fallax, Sp.MOV. ance 2, 
Illenus Davisi var. pseudolim- 
DOLUS Dow, eon, esa ee 2or3 
CT ee EPP RS Sars Ak ahinta Zor 3 


Stages 
Megalasptsyep. 0 ann -.-<donereeeee 2 
1 OP 6 RR PR PE 3 
Phacops Jamesti, Portl. ............ > 
— Brongniarti, Porth, cone 3 
truncato-caudatus, Portl.... 2, 3 
Remopleurideslongicostatus, Portl. 2 or 3 
Salcerd, sp. MOVs ese een caeeee 2or 3 
Trinucleus hihernicus, Reed ...... 3 
concentricus, Haton (?) ...... Qi a 
Tramoria punctata, gen. et sp. 

WOW Seren ras Muscacs Mase eeetenee eee 3 
Beyrichia affinis, Jones ..........+. 2) 3 
Lingula brevis, Portl.............06 2 
Crania (Pseudocrania) sp. ....+.+ 2or 3 
Orbiculoidea elongata, Portl....... 2 
Orthis (Platystrophia) biforata, 


MEGA Wir eas ca electocontnases eee 


Vol. 55.] 


Stages. 
Orthis calligramma, Dalm. ...... 2. 
elegantula, Dalm. (?)......... Zor 3 
Orthisina (2) crispa, M‘Ooy ...... 2 
Plectambonites sericea, Sow. ...... 2 
Porambonites intercedens var. 
Bilose (MOY) ciate de. see e eae sees at Zor 1 


Rafinesquina deltoidea, Cour. ... 2 
expansa, Sow. 
Stropheodonta imbrex, Pand....... 2 


BEDDED ROCKS OF COUNTY WATERFORD. 


733 
Stages. 
Strophomena cf. arachnoidea, 
Horne (2h lias oo sae erate 
Coscinium cf. proavum, Hichw.... ? 
Polypora assimilis, Lonsd.......... 2 
Cyrtoceras sonax, Salt. ............ Zor 1 
FLOLOPEO SION). S20. cae eee Zor 3 
PE QUOSTESF SSC E)) Sowa sone dans sone 2 
Monticulipora (Diplotrypa) petro- — - 
POULGNG, PANG. “ese .sccceseonh 2, 


(c) Garrarus and Kilfarrasy. 


The intrusive felsites [561] [636] [32] exposed in the cliffs in the 
middle of Garrarus Strand contain numerous large included blocks 
and crushed strips of black shales, resembling lithologically those 


near Tramore. 
end of the Strand, 
immediately west of 
a small cave in a 
narrow cleft in the 
cliffs, the black 
shales are seen at 
the level of the 
beach, much shat- 
tered and faulted, 
and penetrated in 
all directions by 
veins of intrusive 
felsites and rotten 
andesitic dolerites 
(83 w][84w][385 w] 
[22], which are also 
crushed and cut off 
by the other felsites 
[81 w] (see fig. 9). 
In the Survey 


Close to the east side of the large spur at the western 


Fig. 9.—WSection at the base of the cliffs, near 
the western end of Garrarus Strand. 


A=Caleareous black shales, much crushed and dis- 
turbed. 
B= Intrusive veins [83 w] [85 w]. 
F F= Faults shifting the intrusive veins. 
EF’ K’=Main line of displacement, marked by much 
crushing of the adjacent beds. 


Memoir the following species from black slates on Garrarus Strand 


are said to have been found :— 


Plectambonites sericea. 
Lingula brevis. 


Asaphus gigas (2). 


Calymene brevicapitata. 
Remopleurides Colbii. 


The slates, which here contain ovoid calcareous concretions, dip 
into the cliff at 60° to 75°, and seem to be i situ from this point 
as far as the western side of the rounded headland (marked 1¥5 on 


the 6-inch Ordnance map). 


A greyish felsite [81 w] overlies these 


slates and encloses patches of them, and several other intrusions 
pierce and disturb them considerably. 
About 30 yards west of the Black Door, at the eastern end of 


734 MR.F,R. C. REED ON THE LOWER PALZOZOIC [Nov. 1899, 


Kilfarrasy Strand, similar slates occur in the bend of the cliffs 
and: ©) -exbend 
westward to Fig. 10.—Cliff-section, Kilfarrasy Strand, on the 


the west side west side of the road to the beach. 
of the road polled) 
‘ Ite 

down to the tee 

- We is My 
Strand. A vol- Age a eh dean tucises 

icneck [96 gee 

“ NZ ,° th 4 uy Wn Way 
canicneck [96] ae HA ali ect . 
[802] pierces x ae 
— Seyi 


them near the 
Black Door ; 
they are every- 
where highly 
cleaved and 
much faulted R 
and folded. A —«si\\ 
greenish felsite Mes Be ee A 
[560] [801], get ee ene ee a ee 
restin g on, and A=Black shales, finely fissile, and crushed at the junction. 
containing nu- B=Intrusive felsite [801] with numerous large xenoliths of 


the shales. 
ETS frag- ¢—Rotten brecciated rock at the junction. 
ments of them, 
extends for 50 yards west of the road (see fig. 10), and then 
a block of limestones similar to those in Tramore Bay is found 
faulted into it (see fig. 11), with many signs of crushing in the 


_ Fig. 11.— Cliff-section, Kilfarrasy Strand, 100 yards west of 
the road to the beach. 


oath 
IN, v 
yh el We yy =fley, ibd ey, Ia) ¥ 
ee Nite tine 8S GELB ORL AM cay MODE whee gy? Eh yy 
My iy ay an Me ta, My MM a fli dey rly MY Dag, 
i “tig tite" rj; Dey y ", ON I NEY LZ 4) yea Vf, 
2 y CO LET fo mc SE 
Ti / j 


y, 2 5 ge 
ipod ictyjes wig cpa 


A=Intrusive greyish felsite [54]. 

B=Impure limestones (Tramore Limestone Series), with black shaly crush- 
zones at the margins. 

C=Intrusive greenish felsite [86] [40], with included strips of shale. 

D=Pale greenish intrusive felsite [25] free from inclusious. 

E=Intrusive vein of pale greyish felsite [67]. 


Vol. 55.] BEDDED ROCKS OF COUNTY WATERFORD. 735 


neighbourhood. Another block of the same limestones, showing 
a sharp overfold (see fig. 12) and penetrated by a vein of felsite [48], 
is found a little farther west beyond a patch of black sandy shales 
at the base of the cliff and an irregular mass of intrusive greenish 
felsite [17]. A third block of the limestones, dipping 45° to 60° 
west-south-westward, is well seen in a stack on the foreshore. 


Fig. 12.—Chiff-section, Kilfarrasy Strand. 


ce sree 


bath 


’ a yy 
ne masa i ongeR A END 
ahi) Y ha nig fey Min Mls 


Pos, 
"aly, Mee iY 
wis, 


A=Impure limestones (Tramore Limestone Series) showing folds. 
B = Intrusive vein of felsite [48] swelling out on the foreshore. 


On the west side of the peninsula called Kil’arrasy Island black 
shales, much disturbed and destitute of any regular sequence, are 
found poorly exposed on the grassy slopes in association with 
shattered greenish felsites [797] and a massive columnar felsite 
[798]. Probably they belong only to an included mass. Towards 
the western end of this straight stretch of coast, but } mile east 
of Green Island, black calcareous slates again appear at the base 
of tbe cliff, and are traversed by numerous veins and tongues of 
green felsites [783] [781] [779], etc. By the zigzag path down 
the cliffs to the beach, about 400 yards east of Green Island, 
shattered and highly cleaved vertical calcareous slates are exposed, 
similar to those of Stage 1 at Dunabrattin farther west, and con- 
taining Monticulipora petropolitana. 


(7d) Annestown and Dunabrattin. 


At the eastern end of Morageeha Strand is an intricate group 
of intrusive felsites, etc. [656] [655], enclosing strips and patches of 
the black shales which form the cliffs to the west, with a general 
north-westerly dip of about 60°, still penetrated by cccasional veins 
and irregular tongues of felsite [651] [652] [653]. In places they 
are much disturbed and contorted. Occasional thin calcareous 
layers, or tougher, less cleaved, slaty bands are intercalated, and in 
one case (fig. 13, p. 736) is seen a sharp sigmoidal fold broken and 


736 MR. F. B.C. REED ON THE LOWER PALZOZOIC [Nov. 1899, - 


displaced. At the Long Rock the group of igneous rocks—mostly 
felsites [716] [717j [718] [721] [722] [723|—breaks through 
them, but they continue westward along Knockane Strand to Boat- 
strand Harbour with but little change, and occasionally pierced 


Fig. 138.—Sceetion of sigmoidal fold in the rocks on Moragecha 
Strand, Annestown. 


F- 


aa +3} ES oS A B 


= FEE = 
EEEEE=ABZ 


= OZ 


~S ZS A> 
SS SSS =a 
ASS SSS => cl a= SEE EAA 

Sao 

ZZ 


DEAE 
—SSS—S_E_ 


BAZ SS 


B=Thick calcareous band in slates. | B‘= | tered and drawn out in the com- 
C=Thin flagey band in slates. C'= } mon limb of the S-shaped fold. 
B"=B much shattered and displaced near the second thrust-plane, TP?. 
D=Black slates. D'=The same, much disturbed. 
TP'=Thrust-plane replacing the middle limb of the fold and truncated by a 
later fault, FF. 
TP? = Probable thrust-plane below the level of the beach. 


A=Thin calcareous band in slates. | AT= [ren much compressed, shat- 


Fig. 14.—Section on the west side of Dunabrattin Head. 


Whitty, oo fivetire OTe bey 5 
WY nace MOG apt Aoi 
ja rzcggrenderatnl nO rirst,,, eet Yi, Bidar 
ee eats SPL Fs Vi tease iy" SS Sif) once gatas yl pee 
oy ae Ht me 
s The Sia sl sohils, = ad's 
CN hae 


yay Se 
tly 

OT AW ERT 
Wal Ore svt 


A=Black shales dipping 8.H. at 45° ; much crushed and shattered in places. 

B=Impure limestones and caleareous shales (Tramore Limestone Series), with 
Porambonites abundant in the lower beds. Same dip as the shales. 

C=Intrusive vein of diabase [770] crushed. 

D=Grey splintery felsite [774]. 


by veins of intrusive felsite [726] [727] [728] [729]. Locally 
they are much disturbed, but in one spot are horizontal. At 
Boatstrand Harbour they dip beneath the fossiliferous limestones of 


Dunabrattin Head, and on the west side of the Head, in a little cove, © 


the section illustrated in fig. 14 is seen. Several masses of diabase 
[770] and dolerite [771] here also occur close to the mass of felsite 
774]. The limestones at their base, which rests conformably on 
the slates, are dark grey, and dip 45° south-eastward. They 


Ce el 


ome 


Vok.ss.| 


BEDDED ROCKS OF COUNTY WATERFORD. 


737 


yielded the following fossils, with numerous bands of Monticulipora 


petropolitana :— 


Phacops Jamesii, Portl. 
Asaphus sp. 
Orthis calligramma, Dalm. 


Orthisina (2) erispa, M‘Coy. 
Porambonites intercedens var. filosa 


(M‘Coy), very abundant. 


Nearer the extremity of Dunabrattin Head, on the north side 
of the western cove, more decomposed and softer calcareous beds 
yielded the following fossils, which indicate the upper part of 
the Tramore Limestones, as in Newtown Cove :— 


Asaphus sp. 

Cheirurus gelasinosus, Portl. 
Llienus sp. 

Encrinurus fallax, sp. nov. 
Phacops Brongniarti, Portl. 
Trinucleus concentricus, Katon (?). 


Trinucleus hibernicus, Reed. 
Primitia mundula, Jones. 
Turrilepas ef. scotica, Nich. & Eth. 
Orthis sp. 

Plectambonites sericea, Don. 
Stenopora (2) fibrosa, Goldf. 


The dip of the beds here varies from 20° to 30° south-eastward, 


and they have suffered several small displacements by faults. 

In the Geological Survey Collection at Dublin are the following 
fossils from Dunabrattin Head; but, as they are not labelled according 
to horizons, it is purely on lithological grounds that we can assign 
them to the different stages :— 


Stage 1. (Brack Arcittaceous Limestone.) 


Asaphus (Ptychopyge?) radiatus 
(Salter), var. 
rectifrons, Portl. 


Asaphus (Ptychopyge) sp. 
Illenus Bailyi, Salt. 
Orthisina (2) crispa, MM‘Coy. 


—- Haughtoni, sp. nov. ? 


Stage 2. 


Plectambonites sp. 


Phacops Jamesii, Portl. 
Orthisina ()) crispa, M‘Coy. 


truncato-caudatus, Portl. 


Megalaspis sp. y. sp. 
Ilienus Davisi, Salt. Orthis biforata, Schloth. 
Lichas sp. Echinosphera sp. 


Plectambonites sericea, Sow. 


Stage 3. 


Cheirurus gelasinosus, Portl. 


Ampyx sp. 
Trinucleus hibernicus, Reed. 


Calymene brevicapitata, Porti. 
Megalaspis sp. y. 


On the rocky slopes on the west side of the extreme point, the 
beds consist of fine-grained, tough, grey calcareous slates, highly 
cleaved, considerably faulted, and nearly devoid of organic remains. 
Towards the eastern side of the headland, where the cliffs are per- 
pendicular, the beds dip in some places 60° south-eastward. 


(e) Knockmahon, 


The tall cliffs along the straight coast-line in the townland of 
Knockmahon consist of a long succession of unfossiliferous, purplish, 
black, greyish, and mouse-coloured earthy slates and soft mudstones, 


738 MR. F. R.C. REED ON THE LOWER PALZOZOIC [Nov. 1899, 


dipping mostly at high angles westward, and pierced by numerous 
small intrusive veins and by several large sheets of felsite [693] 
[690] [692] [243] [239], which are frequently columnar [693] [239]. 
At the eastern end of this long strand the rocks in Foilnaneena 
Cove are much crushed and shattered for a distance of nearly 
50 yards, and constitute a huge mass of vein-stuff composed of 
fragments of felsites, ‘ greenstones,’ the above-mentioned slates and 
mudstones, vein-quartz, etc., all impregnated with copper-ore. 
Below the ruined engine-house on the edge of the cliffs east of 
the cove at Knockmahon, in which is the wooden jetty, occurs a 
mass of fossiliferous limestones (fig. 15) similar to those near Tramore, 


Fig, 15.—Section at the base of the cliff below the engine-house, 
Knockmahon. 


~ 4 (GER ee Sy 
lex FEA 


i B= Se 


A=lIntrusive felsite [687] crushed along the fault-plane F. 
B=Intrusive greyish felsite [686] crushed along the fault-plane F. 
C=Bedded impure limestones traversed by several zones of crushing, O', 
D=Greenish felsite [688] intrusive in H. 

E=lIntrusive vein of felsite [689] penetrating D and H. 

H=Pale purplish, cleaved and disturbed slates. KF F=Faults, 


let in by faults between the slates and igneous rocks [688] [689] 
[686]. The bedding of the limestones is almost horizontal. 

The following fossils have been collected or recorded from this 
locality :— 


S=Survey Collection. G=Sir R. Griffith’s Collection. .M=nmy collection. 


S. G. M. Monticulipora petropolitana. G. Orthis (2) productoides. 
G. Stenopora fibrosa (?). G. simplex. 
S. M. Asaphus sp. G. elegantula. 
8. G. M. Phacops Jamesit. S. M. Orthisina (2) crispa. 
G. truncato-caudatus, G. Porambonites intercedens 
S. Calymene brevicapitata. var. jilosa. 
S. Trinucleus sp. G. Plectambonites sericea. 
G. Orthis biforata. G. Rafinesquina expansa. 
G. calligramma. G. Murchisonia sp. (?). 


(f) Ballydouane Bay. 


At the western end of Ballydouane Bay is a mass of a peculiar 
banded calcareous rock [184 w], called by Kinahan ‘ ophiolite,’ and 
haying very much the appearance of serpentine. This mass is 
bounded on the east by a fault which brings the Old Red Sandstone 


ron. 55. | BEDDED ROCKS OF COUNTY WATERFORD. 739 


beds against it, as described by the present author in a former 
aper.} 

The rock is greenish to purplish-grey, and is banded with light 
green or reddish parallel layers, which have a regular dip ot 60° 
north-north-westward, and apparently represent original planes of 
bedding. It is also frequently traversed by a network of pale 
greenish or yellowish veins, as in the case of serpentine; and 
is in places brightly stained a vivid red or verdigris-green by 
impregnations of iron- and copper-ores. Micaceous hematite also 
occurs on some slickensided surfaces and in veins, in addition to 
a greenish earthy carbonate of copper. There exist also irregular 
nests and bands of pale greenish-yellow epidote, and white quartz 
and calcite—occasionally tinged pink by iron. Sometimes the rock 
seems to have suffered brecciation in place, and subsequently the 
fragments have been re-cemented. 

This peculiar altered limestone yields a few fossils, and I have 
obtained a crushed specimen of an Orthis or Orthisina from it. 
There are specimens of Orthisina sp. (?) also from it in the Geological 
Survey Collection; and in the Memoir are recorded in addition 
(pp. 18, 24, 59) Orthis sumplex, Phacops truncato-caudatus, and Tri- 
nucleus seticornis (probably Z'r. concentricus). 

In the small coves in the headland west of Ballydouane Bay 
these altered limestones are not so distinctly banded, and are under- 
lain by a mass of intrusive nodular felsite [250] associated with 
an earlier intrusion of dolerite [249], which has suffered brecciation 
in places. A volcanic neck of felsitic conglomerate containing 
many fragments of the limestone brings the section to a close. 


(g) Killelton Cove to Ballyvoyle. 


In the western Killelton Cove, part of which is called Lady’s Cove 
on the 6-inch Ordnance map, black unfossiliferous slates (some of 
which are banded) are found in contact with a green felsite [205j, 
and from this point westward to Ballyvooney Cove black and grey 
untfossiliferous slates compose the clitis, with occasional intrusive 
veins, sheets, and dykes of various ‘ greenstones’ [203] and felsites 
[204]. The latter have been affected to some extent by the crushing 
and disturbances which have cleaved or contorted the slates. The 
slates show in several places a distinct north-north-westerly dip at 
angles varying from 60° to 70°. 

On the western side of Ballyvooney Harbour there is found a 
late intrusion of quartz-porphyry (209], with no signs of crushing, 
but enclosing fragments of the cleaved slates and felsites. From 
this spot for about 2 miles westward to Stradbally Creek the cliffs © 
are lofty and precipitous, and consist of similar highly-cleaved 
black and grey slates with bands of’ grit, either vertical or dipping 
steeply north-north-westward. But at about 2 mile west of the 
mouth of the creek the dip of the slates changes to about 70° 
south-westward, At the mouth of the creek they are vertical, and 


Quart. Journ. Geol. Soc, vol. liii (1897) p. 269. 


740 MR. F.R.C. REED ON THE LOWER PAL HOZOIC [Nov. 1899, 


on the west side they dip at 60° to 80° south-westward, with several 
thin interstratified beds of rotten cleaved ash and flagegy layers 
opposite Blind Cove. Beyond this point, as far west as Stradbally 
Beg, grey slates with approximately the same angle and direction 
of dip compose the cliffs, but immediately in the vicinity of the great 
mass of felsite [120 w] [121 w] [122 w] forming the promontory 
their dip changes to the north-east. On the western side of the 
headland the old south-westerly dip, however, again sets in. 

On a small promontory about 7 mile east of Ballyvoyle Head, the 
slates are seen to dip at angles varying from 45° to 60° north-east- 
ward ; and in the well-known section at the Head itself (illustrated 
in the Survey Memoir, fig. 7, p. 60) they dip northward at 60°, and 
have the Old Red Sandstone resting unconformably on their edges. 

No fossils have so far been found in these slates along the coast. 


ILL. GENERAL SUCCESSION AND SUBDIVISION OF THE STRATA. 


Where the succession is most complete, as near Tramore, we find 
at the base dark grey or black unfossiliferous slates which may be 
conveniently called the Tramore Slates. Above these come a 
series of impure limestones, which may be termed the Tramore 
Limestone Series. These are dark grey at the base, and pass 
down into the underlying slates, constituting Stage 1 of the series. 
These beds are also well exposed on the west side of Dunabrattin 
Head, as before mentioned. 

Separated from these lower beds by no strong lithological differ- 
ence, but generally by a more arenaceous character and paler colour, 
comes the main mass of the limestones, These constitute Stage 2, and 
are well displayed along the west side of Tramore Bay and also at 
Dunabrattin Head. The limestones faulted in among the igneous 
rocks at Kilfarrasy and Knockmahon, and probably the altered 
calcareous beds of Ballydouane Bay, belong to this stage. <A typical 
fossil of this horizon, not occurring in the overlying stage, is Phacops 
Jamesit. 

The uppermost group of beds of the Tramore Limestone Series, 
forming Stage 3, is more argillaceous -and fossiliferous; it is 
especially well developed in Newtown Cove, near Tramore, and 
occurs also at Dunabrattin Head. One of the characteristic species 
which are not found in the underlying beds is T'rinucleus hibernicus. 
It is probable that the ‘ black shaly beds’ on the shore at Garrarus 
Strand, containing a few fossils, belong to this horizon. I have 
searched these beds at this locality without obtaining any recog- 
nizable specimens, and unluckily those collected by the Surveyors - 
cannot be found (except one, namely, Lingula brevis). 

Above Stage 3 of the Tramore Limestone Series in Tramore Bay 
comes the variable series of graptolitic shales, thin interbedded grits, 
tuffs, cherts, and felsites. At no other place along the coast have beds 
with a similar fauna been found; but it is possible that some of the 
patches of black shales caught up and entangled among the later 
intrusive rocks at Garrarus, Kilfarrasy, and elsewhere may belong to 
this series. This group of beds, as developed in Tramore Bay, may 


Wal cs. | BEDDED ROCKS OF COUNTY WATERFORD. 741 
be called the Carrigaghalia Series, from its typical fossiliferous 
exposures near the rock of that name, 

The shales near Newtown Head may be called the Raheen 
Shales, from their only exposure near the Raheen stream, and 
their fauna indicates a higher horizon than even the Carrigaghalia 
Series ; for the Orthis argentea-zone, to which they may be compared, 
lies at the top of the Dicranograptus-shales, to which it will be shown 
that the graptolitic beds of the Carrigaghalia Series correspond. 

The felsitic lavas and tuffs and the greenish slates, mudstones, 
etc., which overlie the Raheen Shales, are therefore the highest 
rocks of the bedded series as yet observed. There is mo evidence 
to show to what the lavas, etc. below the Raheen Shales exactly 
correspond. As for the thick mass of barren limestones at Duna- 
brattin Head above the beds with the Tramore Limestone fauna, 
it can only be said that they rest conformably upon Stage 3, and 
apparently form part of the same series. 

The relative positions of the beds, and loeal succession and corre- 
lation, are represented in the accompanying table (p. 742). 


IV. Patmontoxtoeicat Norss. 


(Pl: be) 


Many of the fossils from the Ordovician beds on the Waterford 
coast have been mentioned or described by various paleontologists. 
The references to the papers by Baily and Lapworth on the grapto- 
lites have been previously given (see pp. 720, 731), and other 
references are given below. In M‘Coy’s ‘ Synopsis of the Silurian 
Fossils of Ireland,’ published in 1846, the following species from 
Waterford are mentioned :— 
Murchisonia corallii, Sow. Knock- 


mahon, Tramore. 
Leptena complanata, Sow., var. do. 


Encrinurus Stokesti, M‘Coy. 
Newtown Head. 
Phacops Jamesti, Portl. Knockmahon, 


sericea, Sow. do. Tramore, 
Orthis alternata, Sow. do. Murchisont, Portl. do. 
~—— concentrica, Portl. do. Asaphus Buchi, Brongn. (?). 
crispa, M‘Coy. do. Newtown Head. 
—— eleganiula, Dalm. do. & New- | Trinucleus seticornis, His. do. 
town Head. | Ampyx nasutus, Dalm. do. 
— (2) productoides, M‘Coy. Knock- | Favosites fibrosa, Goldf. Knockmahon, 
mahon, ‘'ramore. Tramore. 
——- pseudopecten, M‘Coy. do. petropolitana, Pand.(?). do. & 
-——— rugifera, Portl. do. Ballydouane Bay. 
—— simplex, M‘Ooy. do. Acanthalepis Jamesiz, M‘Coy. 
virgata, Sow. do. Newtown Head. 
Spirifer tridens, M‘Ooy. do. 
Atrypa filosa, M‘Coy. do. 
Portlock’ had previously mentioned some species from County 
Waterford :— 
Ampyx Austinii, Portl. Tramore. | <Asaphus dilatatus, Dalm. Newtown 
Phacops Jamesti, Port. do. Head. 


Amphion pseudoarticulatus, | 5 
Portl. _ 


Illenus crassicauda, Dalm. Tramore. 


1 ‘Rep. Geol. Londond.’ 1843, pp. 261, 283, 291, ete. 


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LOWER PALZOZOIC ROCKS OF COUNTY WATERFORD. 


743 


Davidson’ records a number of brachiopoda from the beds on 


Wol.5s. | 
the coast :— 
Tingula ovata, M‘Coy. Newtown Head. 
brevis, Portl. do. 
Crania divaricata, M‘Coy. do. 
Discina oblongata, Portl. Tramore. 
Porambonites inter- | Dunabrattin, 
cedens var. filosa Knockmahon, 
(M‘Coy). Tramore. 
Orthis elegantula, Dalm. 
calligramma, Knockmahon, 
Dalm. Tramore. 


Orthis simplex, M‘Coy. Knockmahon, 


Tramore, 
—— crispa, M‘Coy. do. 
— biforata, Schloth. do 


—-(?) productoides, M‘Coy. do. 
Strophomena simulans, M‘Coy. do. 
corrugatella, Day. | Newtown. 
—— expansa, Sow. Knockmahon, 
Tramore. 


Many of the trilobites were first described and named by Salter. 
In his monograph’ the following species are described from 


Waterford :-— 


Phacops Jamesii, Portl. 
Brongniarti, Portl. 
—- Bailyi, Salt. Tramore. 


Amphion pseudoarticulatus, Portl. 

Tramore. 
Amphion benevolens, Salter. Newtown 
Head. 


Amphion pauper, Salter. Tramore. 
Calymene senaria, Conr. 
duplicata, Murch. 
Barrandia Portlockii, Salt. Newtown 
Llienus Bowmani, Salt. [ Head. 
Bailyi, Salt. Dunabrattin. 


In the Decades of the Geological Survey * several other species 


are described :— 


Ogygia [Barrandia] Portlockii, Salt. 
Newtown Head. 


Ampyx mammillatus, Sars. do. 
—— rostratus, Sars. do. 
Phacops Jamesii, Portl. | Waterford. 
Acidaspis Jamesii, Salt. Newtown. 


Trinucleus Thersites, Salt. Tramore. 


Trinucleus seticornis, His. Newtown. 
Remopleurides Colbit, Portl. Tramore. 


dorsospinifer, Portl. do. 

longicostatus, Portl. do. 
Salterta involuta, Salter. Newtown 
Head. 


There is finally the long list of fossils in the Geological Survey 
Memoir of County Waterford (Sheets 167, 168, etc.). 

I have myself examined all M‘Coy’s specimens used in compiling 
his ‘ Synopsis,’ and have identified the following :— 


Acanthalepis Jamesit ........000.005 = 
Orthis concentrica \ 

Orthis rugifera 
Orthis elegantula, Newtown Head == 
Atrypa filosa 
Asaphus Buchi 
Trimucleus seticornis ............++- = 
AMPYL NASULUS .ocsccrecercerensaees = 
Orthis virgata 
WPUCUF ER UT UAENS ©. atte ancaeusee es wens = 
Phacops Murchison ............+.. = 
Encrinurus Stokest (pars) ......... == 
Leptena complanata .........s.000 = 


Sere eee erssesce 


Pete e reese eee reser eseeee 


Pere sere eter eereeses 


Glyptocystis ef. pennigera, Eichw. 
Rafinesquina expansa, Sow. 


Orthis argentea, His. 

Porambonites intercedens var. filosa. 
Barrandia Portlockii. 

Trinucleus hibernicus. 

Ampyx mammillatus. 

Orthis calligramma, Dalm. 

Orthis biforata, Schloth. 

Phacops Brongniarti. 

Cybele sp. 

Rafinesquina deltoidea. 


Orthis [ Orthisina ?| crispa, Leptena [ Plectambonites] sericea, Orthis simplex, 
O. (2) productoides, Phacops Jamesii, and Favosites | Monticulipora] petropolitana 
hold good, so far as the specimens allow of specific characters being determined. 


1 Monogr. Paleont. Soe. ‘ Brit. Silur. Brach.’ vol. iii, pp. 38, 50, 78, ete. 
2 Monogr. Palzont. Soc. ‘ Brit. Trilob.’ pp. 32, 34, 44, etc. 
> Mem. Geol. Surv. dec. ii (1849) pls. vil & x; dec. vii (1853) pls. i, vi, & vii; 


dec. xi (1864) pl. vi. 


144 MR. F. R. C. REED ON THE LOWER PALH0ZOIC [Nov. 1899, 


The characteristic feature of the Tramore Limestones and Raheen 
Shales is the abundance and variety of the trilobites. They are 
by far the commonest fossils, and their vertical distribution is also 
of stratigraphical importance. The brachiopoda are not numerous, 
and the scarcity of mollusea and actinozoa is most noticeable. 

An important feature is the occurrence in these beds of several 
peculiar genera or species which are extremely rare or unknown 
from other British localities. Such are Amphion, Megalaspis, 
Tramoria, Porambonites, Cosconium; and the species of Ampyw, 
Cybele, Barrandia, Acidaspis, etc. A few of the forms occur in 
Tyrone or in the Balcletchie Beds. The following species 
have not been found elsewhere in the British Isles:— 


Acidaspis Jamesit, Salter. Phacops Jamesit, Portl. 
Amphion benevolens, Salter. Bailyi, Salt. 
pauper, Salter. Salieria tnvoluta, Salt. 
Ampys cf. Volborthi, Schmidt. Tramoria punctata, gen. et sp. nov. 
ef. Portlocki, Barr. Trinucleus hibernicus, Reed. 
Asaphus Haughtont, sp. nov. Remopleurides Portlock, sp. nov. 


Salteri, sp. nov. 
tuberculatus, sp. nov. 


Barrandia Portlockii, Salt. 
Cybele cf. bellatula, Dalm. 


Mc Henry, sp. nov. Beyrichia affinis, Jones. 
ef. rex, Nieszk. Orthisina cf. squamata, Pahl. 
sextuberculata, sp. nov. Porambeonites intercedens var. filosa 
— tramorensis, Reed. (M‘Coy). 
Encrinurus fallax, sp. nov. Hyolithes cf. striatus, Hichw. 
Tlienus Bailyi, Salt. Coscinium ef. proavum, Hichw. 
—- Davisi var. pseudolimbatus Glyptocystis ef. pennigera, Kichw. 
nov. Monticulipora (Diplotrypa) petrepoli- 
——- ef. Dalmani, Volb. tana, Pand. 


TRINUCLEUS HIBERNICUS, Reed. 


The specimens attributed to Tr. seticornis, His., from the fossili- 
ferous localities on the Waterford coast, and thus recorded in the 
Survey Memoir, etc., are found to belong to Zr. hibernicus.’ Tr. 
seticornis has not so far been observed by me in any collection 
from Waterford. Tr. hibernicus is extremely abundant at Newtown 
Cove, and has also been found on the same horizon at Dunabrattin 
and in the Raheen Shales at Newtown Head. There is a fine 
specimen of a complete individual from Dunabrattin in the Geological 
Survey Collection, from which the following details may be added 
to the description of the species previously published. 

The genal spines are very long and straight, and extend parallel 
to each other behind the pygidium for a distance nearly equal to 
that of the whole trilobite, much resembling those in 7. Bucklandi, 
Barr. 

There are six segments (as usual) in the thorax with flattened, 
straight-pointed pleure. The axis is about one-quarter the whole 
width of the thorax. Each pleura is divided diagonally into two 
parts, the anterior portion being flattened and widening towards the 
point, and the posterior portion elevated and narrowing towards 


1 Geol. Mag. 1895, p. 52, 


Wol. 55.| BEDDED ROCKS OF COUNTY WATERFORD. 745 


the point. The obscure fulcrum is situated where the pleura bends 
sharply back to end in the short point. A narrow articulating 
band runs along the anterior and posterior edges of each pleura. 

The pygidium is about three times as broad as long, with a short 
conical axis nearly reaching the posterior margin and marked with 
six rings, the grooves that separate them being strongest and deepest 
at the sides. The pleural portions are flat, and show only one or 
two faint furrows. 


MEASUREMENTS. 
mn. 
Total length of trilobite from front of fringe to extremity of pygidium . 15°5 
Length of the genal spines behind the pygidium ............cccccseeseeseeees 12:0 
Total length of the genal spine from the genal angle .................:ee000 16:0 
mm. mm 
Moneinol head) «2. ...5--.<e0cees 7°0 Width of thorax ...........-..- 10:0: 
GUIS ED. mer ae eee 55 2 BRIS) a ateonen sae ge 2°5 


32 


Pi PY SAUNA. sence en 3:0 


Ampyx cf. Vorzortui, Schmidt. 


The species of Ampys which occurs most frequently in Stage 3 
of the Tramore Limestone Series at Newtown Cove is distinct from 
A. mammillatus, and does not seem referable to A. costatus. It 
approaches most closely that named by Schmidt’ A. Volborthi from 
Stages Be & B3,in Russia. Our specimens arenot, however, sufficiently 
perfect to admit of a close comparison. The head-shields most 
resemble Schmidt’s fig. 12, pl. vi; and the pygidia, fig. 17, pl. vi. 
It is a large form, one of the head-shields (without the spine) 
measuring 18 mm. in length. 


Harpes Franacant, Portlock. 


The single specimen of this species from the Waterford area is in 
the Dublin Museum. It comes from Newtown Head, and consists of 
a nearly periect cast of the under-surface of a head-shield. With 
the exception of the coarser nature and irregular distribution of the 
pores in the limb, it shows a close resemblance to the Russian 
species H. Spasskii (Kichwald)’ from the Echinospherite-limestone 
Ci. The linear arrangement of the pores, described by Schmidt? as 
existing on the limb of this foreign form, is not observable, but on 
the cheeks the fine raised radiating lines with rows of pores between 
them are fairly distinct. Portlock’s* figures and description of 
H. Flanaganz \ack detail, but the description which Schmidt gives of 
the glabella, cheeks, position of eyes, etc. in H. Spasskic would apply 
without much modification to the Irish species. 


1 «Rey. Ostbalt. Silur. Trilob.’ pt. iv, Mem. Acad. Imp. Sci. St. Petersb 
ser. 7, vol. xlii (1894) no. 5, p. 80 & pl. vi, figs. 11-20. 

2 Hichwald, ‘Sil. Schichtensystem vy. Estland, 1840, p. 86; and ‘Leth 
Ross.’ 1860, p. 1375 & pl. li, fig. 27. 

3 «Rev. Ostbalt. Silur. Trilob.’ pt. iv, p. 66 & pl. v, figs. 3-9. 

* «Rep. Geol. Londond.’ 1843, p. 268 & pl. v, figs. 5-7. 


Q.J.G.8. No. 220. 3¢ 


746 MR. F. R, C. REED ON THE LOWER PALXOZOIC [Nov. 1899, 


ReEMOPLEURIDES PorTLocKI, sp. nov. (Pl. XLIX, fig. 4.) 


In the Geological Survey Collection at Dublin there are two 
specimens (Nos. 1278 & 1455) labelled R. Colbi, which apparently 
belong to a new species of the genus, distinct from any of those 
hitherto described from British localities. One of the specimens 
(No. 1278) is the cast of a head-shield without the free cheeks. 
The glabella is large, flattened, transversely oval, twice as broad 
across the middle as across the base, and produced in front into a 
wide obtuse tongue of the same width as the base of the glabella, 
and in length equal to about one-third that of the glabella. The 
narrow eyes embrace the sides of the glabella, slightly indenting its 
base on each side, and reaching from the neck-furrow to the 
tongue. They decrease in width from the base forward, forming 
only a very narrow band towards the front. 

The surface of the glabella is marked by two pairs of slightly 
curved furrows directed obliquely backward. The anterior pair, 
which is the stronger, is situated at about half the length of the 
glabella, and neither pair reaches the axial furrows, each member 
forming an isolated groove on the surface of the glabella, as in 
R. radians, Barr. In addition to these furrows the whole surface 
of the glabella is ornamented with fine transverse but slightly wavy 
lines, not concentric with the margins, but roughly parallel to the 
neck-furrow. The latter is well marked, and separates off the 
rounded neck-ring, which has precisely the same ornamentation. 


MEASUREMENTS. 


Length of head-shield .................. 9 
~ glabella, including tongue . 7 
Width of glabella across the middle ... 9 
ss pun tn thie (hase) ioe. seses 5 
4s tongue of glabella_......... 5 


This species occurs in Stage 2 of the Tramore Limestone Series 
of Tramore Bay. 

Affinities.—The presence of furrows separates this form at 
once from all British species’ except A. radians, Barr.” and R. 
Barrandit, Nich. & Eth. From &. radians it differs in the pre- 
sence of only two pairs of furrows, in the width of the projecting 
tongue of the glabella, and in the ornamentation. From &. Bar- 
randu it differs in the rounder shape of the glabella, the shorter 
tongue, the longer eyes, the direction and position of the furrows, 
and the ornamentation. The lineation of the glabella recalls some- 
what that found in R. longicostatus, Portl, &. nanus, Leucht.* 
shows a somewhat close resemblance in the shape and proportions 
of the head-shield, but no ornamentation has been described in this 


1 Mem. Geol. Surv. dec. vii (1853) pl. viii. 

2 «Syst. Silur. Boh.’ 1852, vol. i (Trilob.) p. 859 & pl. xliii, figs. 33-39. 

3 «Mon. Sil. Foss. Girv.’ 1880, p. 151 & pl. x, figs. 13-16. 

4 Schmidt, ‘ Rev. Ostbalt. Silur. Trilob.’ pt.iv (1894) p. 88 & pl. vi, figs. 84— 
35, and references. 


Vol. 55.] BEDDED ROCKS OF COUNTY WATERFORD. TAG 


form, and it has usually three pairs of furrows. . Jentzscha, 
Pompeckj,' appears also to be allied in many respects, but shows no 
ornamentation. 


REMOPLEURIDES SALTERI, sp. nov. (Pl. XLIX, figs. 1-3.) 


There is another form from Tramore in the Dublin and Cambridge 
collections possessing a peculiarly shaped transverse glabella, which 
shows several characteristic features. The glabella is transversely 
oval, broadest at about one-third of its length from the neck-furrow, 
and with rounded but well-marked lateral angles near the base, 
round which the eyes bend sharply. In front it is produced into a 
short narrow tongue of about one-fourth the maximum width of 
the glabella. The band-like eyes embrace the sides of the glabella 
and slightly indent its base, where they are nearly as wide as the 
neck-ring. 

The surface of the glabella is marked by two pairs of short, 
slightly curved, isolated furrows. ‘The posterior pair is about half 
way between the neck-furrow and anterior pair. In young speci- 
mens both pairs are very faint. In addition to these furrows the 
glabella possesses a conspicuous ornamentation consisting of fine 
wavy, rather irregular lines, particularly strong in young individuals, 
and concentric to the margins, near which they are most distinct. 
Abundant small tubercles are dispersed between them, and are a 
characteristic feature. 

The neck-ring is rounded, short, and broadest in the middle, the 
lateral angles being pointed, owing to the strong neck-furrow 
curving backward at the sides. The neck-ring is ornamented with 
rather larger tubercles than those on the glabella, and they appear 
to be generally arranged in four or five rows, the largest forming 
the posterior marginal row. 

There is one specimen with seven body-rings attached to the head- 
shield. ‘These show a broad axis about three times the width of 
the narrow pleure, as in ft. Colbiz; but the rate of tapering of the 
axis is slower than in this species, the width of the axis of the first 
body-ring being 3°5 mm., and that of the seventh being 2°5 mm. 
The axial rings are covered with small tubercles and granulations, 
the larger tubercles being arranged along the posterior edge. The 
pleure are short, faleate, curved backward, with a strong short 
oblique furrow running back from the prominent fulcral tubercle 
situated on the front border close to the axis. A corresponding 
notch is found on the posterior border. The pygidium is unknown. 

This species seems allied to R. Portlocki, but the ornamentation 
is very distinct. 


MEASUREMENTS. LP HH: 
mm mm. 

Length of head-shield .................. 6:0 4:0 
4 BEE MAW AM Rw PddeseeS! 50 3'0 
Maximum width of glabella............ fh, 50 


Width of glabella at the neck-furrow 2°25 20 


1 Beitr. zur Naturk. Preussens, ‘ Die Trilobitenfauna d. ost- u. westpreuss. 


diluy. Geschieb.’ 1890, p. 87 & pl. i, figs. 31 a & 6. 
302 


748 MR. F. R. C. REED ON THE LOWER PALZOZOIC [Nov. 1899, 


Occurrence.—From the character of the rock the specimens 


seem to have come from the lower part of Stage 3, Tramore Lime- 


stone Series. 


REMOPLEURIDES TUBERCULATUS, Sp. noy. (Pl. XLIX, fig. 5.) 


Glabella subcircular to transversely oval, moderately convex, with 
large abruptly projecting frontal tongue, with parallel sides and 
rounded anterior end, measuring in length two-fifths that of the 
glabella, and in breadth rather more than one-third its greatest 
width. 

Surface of glabella marked by one distinct pair of basal furrows 
obliquely curving backward, but not reaching the neck-furrow or 
axial furrows. An indistinct second pair is observable in some 
specimens. The whole surface is also ornamented with coarse 
tubercles of equal size. 

Eyes narrow, linear, encircling the sides of the glabella, and in- 
denting its base, where they rather suddenly increase in width as 
they bend round to the neck-furrow. 

Neck-furrow deep. Neck-ring rather narrow antero-posteriorly, 
measuring only about one eighth the length of the glabella, and 
ornamented with similar tubercles not arranged in rows. 


MEASUREMENTS, 


Tength of head-shield. ....:...2::00.<0s 15:0 
glabella, including tongue. 13:0 

Width of glabella across the middle. 13°5 
s at the neck-furrow. 6:5 

Length Ol HOMSUC) (cree secon cence 50 
Wadth of tommue (ite oo. .csccaes arrestee 5:0 


The tuberculated glabella of this species recalls Salter’s descrip- 
tion of R. platyceps, but in no other respect do the species resemble 
one another. The single pair of furrows and the tuberculated 
surface of the glabella mark it off from &. Portlocki and R. Salterd. 

R. Barrandu, Nich. & Eth. has three pairs of furrows and other 
points of difference. . Panderi, Billings’ agrees in having a single 
pair of furrows, and fF. canadensis, Billings® in possessing a 
tubercular ornamentation. 

Occurrence.—R, tuberculatus is found at the top of Stage 2 
and in Stage 3 of the Tramore Limestone Series in Newtown Cove. 


CHEIRURUS GELAsINOSUs, Portlock. 


Occurs in Stages 2 & 3 of the Tramore Limestone Series. The 
larger specimens show the typical characters as described in detail 
and figured by Salter. Some of the smaller specimens, which I 
attribute with some hesitation to this species, may possibly owe their 
points of difference to age, but they show a remarkable resemblance 


1 Billings, ‘ Pal. Foss. Canada,’ Geol. Surv. Can. vol. i (1861-1865) p. 293 & 
fig. 283. 

2 Ibid. p. 128 & fig. 164. 

3 Monogr. Palzont. Soc. ‘ Brit. Trilob.’ p. 71 & pl. v, figs. 6-8. 


Vol. 55.] BEDDED ROCKS OF COUNTY WATERFORD. 749 


to some individuals of the very variable species Ch. exsul, Beyr.’ 
which occurs in the Echinospherite-limestone C1 of Russia and the 
equivalent beds of Scandinavia. 


Puacops Jamesit, Portlock. 


This species does not appear to have been recorded outside 
Treland. Its original discoverer * records it from the ‘Silurian 
schists of Tramore, County Waterford.’ Salter* records it from 
«Newtown on the Suir,’ and in his monograph* from Tyrone as 
well. The Geological Survey Memoir on the Waterford area 
frequently confuses this species with Ph. Brongniarti, as I have 
previously mentioned elsewhere.’ It is characteristic of Stage 2 of 
the Tramore Limestones, and is especially abundant at Quillia and 
Pickardstown. In the upper beds (Stage 3) its place is taken by 
Ph. Brongniartit. I have nothing to add to Salter’s description 
of the species, except that some individuals have the front slightly 
pointed, as in the supposed male form of Ph. Brongmarti.® 

Schmidt ” is inclined to place Ph. Jamesii and Ph. Brongniarti in 
the subgenus Pterygometopus, which is especially characteristic of 
Stages Bs & C1 in Russia. Ph. sclerops (Dalm.) is the type of 
this subgenus, but Ph. Jamesiz is certainly most nearly allied to those 
members of it which are transitional to Chasmops. So far as the 
characters of the glabella go, Ph. Jamesii bears the closest resem- 
blance to Ph. ingrica, Schmidt (op. cit. p. 95 & pl. ii, fig. 16), which 
occurs in the Echinospherite-limestone C1 and is one of these 
intermediate forms. 


Puacors BronentaRti, Portlock. 


Unlike Phacops Jamesi, this species has been recognized in various 
localities in the British Isles. It is readily distinguished from 
Ph. Jamesvi by the larger eyes and characters of the glabella, but, as 
above stated, it has been confused with it in the Survey Memoir, 
so that the species Ph. Jamesti does not appear in the list. 
Ph. Brongmarti appears also to mark a slightly higher horizon 
than Ph. Jamesw, for it is most abundant in the upper beds in 
Newtown Cove, while it is rare (or absent?) in Stage 2 of these 
limestones. Schmidt’ compares this species with his Ph. trigono- 
cephala from the Orthoceras-limestone B3, but it seems to me to 
be more allied to some of the higher forms which pass into 
Chasmops, and are specially characteristic of the higher stage C1 in 
Russia. 


1 Schmidt, ‘Rev. Ostbalt. Silur. Trilob.’ pt. i, Mem. Acad. Imp. Sci. St. 
Petersb. ser. 7, vol. xxx (1881) No. 1, p. 187, and references to Ch. exsul and 
its subspecies. 

? Portlock, ‘Rep. Geol. Londond.’ 1843, p. 283. 

3 Geol. Surv. Mem. dee. vii (1853) No. 1, p. 10. 

* Monogr. Palzont. Soe. ‘ Brit. Trilob.’ 1864, p. 32. 

® Geol. Mag. 1897, p. 505. 

6 Salter, Monogr. Palxont. Soc. ‘Brit. Trilob.’ 1864, p. 35. 

7 *Rev. Ostbalt. Silur. Trilob.’ pt. i (1881) p. 62. 

8 Ibid. p. 81. 


750 MR. F. R. C. REED ON THE LOWER PALMOZOIC [ Nov. 1899, 


I am doubtful whether it occurs at Newtown Head, but it is 
abundant at Newtown Cove, and is also found at Dunabrattin in 
Stage 3 of the Tramore Limestone Series. 


PHACOPS TRUNCATO-cAUDATUS, Portlock. 


Rare ; occurs in Stages 2 & 3 of the Tramore Limestone Series. 

Salter * records it only from Tyrone, but I have found it myself at 
Tramore and inland, and there are specimens of it in the Survey 
Collections in Dublin. It belongs to the subgenus Pterygometopus, 
but shows certain features linking it rather closely to Chasmops.” 


Puacors Bartyt, Salter. 


Salter (op. cit. p. 44) described this species from the ‘ Caradoc 
Slates of Tramore.’ It is atypical Pterygometopus, comparable with 
Ph. sclerops, Dalm. and other allied forms from the Orthoceras- 
limestone of Russia and Scandinavia. | 


CALYMENE BREVICAPITATA, Portlock. 


In Stage 2 of the Tramore Limestones this species is the common 
Calymene. It also occurs associated with C. Blumenbachi var. 
Caractaci in Stage 3. Salter’s® views on the synonymy of C. brevi- 
capitata do not commend themselves to me. The head-shield 
certainly agrees in many respects with C. senaria, Conrad, but in 
the indistinct and indefinitely defined anterior pair of glabellar lobes 
it more closely resembles C. cambrensis, Salter. The rounded and 
elevated border to the front of the head-shield, however, distin- 
guishes it from the latter. The pygidium differs from both these 
_ species in possessing only four rings on the axis, of which the 
posterior one is very faint, and in having only four grooved pleure 
on the lateral portions. The short broad shape of the axis also 
distinguishes it from C. cambrensis. 

Our Tramore form is almost identical with Salter’s fig. 5, pl. ix, 
which he says is C. brevicapitata, Portl. in part. The whole head- 
shield, thorax, and pygidium are ornamented with fine tuberculations. 
There is no doubt in my mind that this form is distinct from 
C. senaria, Conr.* as defined by Salter, and also from C. brew- 
capitata, Portl. as described by M‘Coy,’ whose type-specimen 
Salter rightly attributes to C. cambrensis. 


CYBELE TRAMORENSIS, Reed. (Pl. XLIX, fig. 6.) 


This species, which has been previously described by the present 
author,® was founded on an imperfect head-shield. But there is a 
specimen from Stage 2 of the Tramore Limestone Series of Tramore 
in the Dublin Museum which shows also a well-preserved fixed 


1 Monogr. Palzont. Soc. ‘ Brit. Trilob.’ 1864, p. 44. 

2 Schmidt, ‘ Rev. Ostbalt. Silur. Trilob.’ pt. i (1881) p. 63. 

3 Monogr. Palzont. Soc. ‘ Brit. Trilob.’ pp. 96-99 & pl. ix, figs. 5-7. 
* Pompeckj, Neues Jahrb. 1898, vol. i, p. 200. 

> * Brit. Pal. Foss.’ 1855, p. 165 & pl.i F, figs. 4 & 5. 

® Geol. Mag. 1895, p. 49. 


Vol. 55.] BEDDED ROCKS OF COUNTY WATERFORD. Tol 


cheek, and therefore some further notes on the species may be given 
here. 

The posterior outer portion of the fixed cheek is much produced 
laterally, and the posterior border of the cheek curves steadily 
backward to the genal angle, which is bent downward and pro- 
duced into a rounded spine that has been broken off short, but is 
most distinct. This is a most uncommon, if not unique, feature 
in the genus. 

The eye-ridge runs at right angles to the axial furrow, from the 
level of the anterior glabella-furrow to the base of the long stalk- 
like eye-lobe, which is situated at a distance from the axial furrow 
about equal to the width of the glabella, and is directed obliquely 
forward, outward, and upward. 

There are three large tubercles on the fixed cheek, the inner two 
being in a line parallel with the axial furrow. 


MEASUREMENTS. 
mm. 
BRST OL CVC TIES. oBaee es ssteet «deci aw sisaigiauen ocietive coll sane eee eee Reacts 6-0 
ee MeV LODE SEALS & pUodigeh voces set'ss eh aaiesnes encecaeeaceemereee ae ee 4:0 
,, fixed cheek from the eye-ridge to the posterior margin ... 9:0 
Width of fixed cheek, measured obliquely from the base of the eye- 
HIE TpO Wee EMA ySPUNCY ioc t cise nay conn sale saciesan see <ouccapeh aayeMe eee 16°0 


CyseLe McHenryi, sp. nov. (Pl. XLIX, fig. 7.) 


Head-shield semilunar, twice as broad as long, slightly convex, 
and arched from side to side. Genal angles rounded. 

The glabella occupies about the middle fifth of the breadth of the 
head-shield, is cylindrical, nearly parallel-sided, gently convex, rising 
highest in the centre between the first pair of lateral lobes. The 
anterior end is obtusely pointed. The length is about one and a 
half times the breadth. The central portion of the glabella is 
marked off, and swells up between the lateral lobes, rising above 
them, so that the glabella appears divided into a median raised 
and two depressed lateral portions. Straight, almost parallel axial 
furrows mark off the glabella on each side and curve round its 
anterior end, defining there a narrow depressed border bearing 
a row of marginal tubercles along its outer edge. The sides of 
the glabella are marked by three pairs of strong, short, lateral 
furrows, slightly oblique, and rather less in length than one-third 
of the width of the glabella. The two posterior pairs of furrows 
are of equal depth along all their length, and are nearly at right 
angles to the axial furrows. The anterior pair is rather less deep, 
but more oblique to the axial furrows. 

The basal lateral lobes and second pair are of equal size, but the 
first (anterior) pair is rather larger and more swollen, though less 
sharply defined. 

The frontal lobe is large, more than one-third of the length of the 
glabella, obtusely pointed in front, and with obtuse lateral angles, 
opposite which is the usual pair of deep lateral pits at the anterior 
ends of the axial furrows. 


752 MR.F.R.C. REED ON THE LOWER PALHOZOIC [Nov. 1899, 


The occipital ring is marked off by a strong neck-furrow, is 
rounded, and wider in the centre than at the sides. 

The fixed cheeks are wide, gently convex, with the genal angles 
rounded. A strong neck-furrow marks off the neck-ring, which 
broadens gradually towards the genal angle. 

The eye is situated at about one-third of the width of the glabella 
from the axial furrow, and opposite the second glabellar furrow. The 
eye-ridge runs out from the level of the first glabelJar furrow to the 
eye. 

The posterior branch of the facial suture runs almost parallel to 
the posterior edge of the head-shield; the anterior branch curves 
inward and forward to the front border. 

The ornamentation is important. It consists of scattered tu- 
bercles of two or three sizes, but none are very small. They are 
distributed all over the glabella, cheeks, and neck-ring, and, except 
on the glabella, have no definite arrangement. On the glabella 
those of the first size seem to have a regular plan of arrangement. 
On the frontal lobe there are two median parallel pairs of large 
tubercles, placed so as to form a square, with also two smaller 
tubercles closer together in front. Inside the square is a diamond 
pattern, formed by four small tubercles. 

Behind these, on the central portion of the glabella, are six large 
tubercles roughly arranged in three rows. 


MEASUREMENTS. 
mm. 
ensthiof head-shield (is. di0. 268: ss ssaccarestoskecees 70 
Wadthvor, the same. o-500 ont ce sows Sai Sassi See en eee 14:0 
Length of glabella ..... Dred cchaeeecascedeainec unease carer act 50 
Widthiot the sane eo e.o. 5 tec ence case ree ck seeeceere 4:0 


This species is allied to C. verrucosa, Dalm. but differs from it 
in the shape and characters of the glabella and lateral lobes. In 
these points it resembles C. rev, Nieszk. but differs in the tuber- 
cular non-punctate cheeks and absence of frontal marginal spines. 

The form of the glabella, fixed cheeks, position of eyes, and 
tubercular ornamentation ally it to C. Worth, Hichw. and 
C. affinis, Schmidt, but it differs in the lobation and furrows of 
the glabella. Though the ornamentation reminds one of C. bella- 
tula, Dalm. yet the position of the eyes and glabellar characters 
are completely different. 

In these beds of Newtown Head C. rugosa, Portl. occurs, and it 
may be that C. McHenryi is merely the head-shield of this species. 
But until the pygidium of the one is definitely found in connexion 
with the head-shield of the other, it seems to me safer to keep them 
distinct. 


CYBELE SEX-TUBERCULATA, sp. nov. (Pl. XLIX, fig. 8.) 


A slightly distorted head-shield of a new species of Cybele 
(No. 1412) which is in the Geological Survey Collection at Dublin 
comes apparently from Stage 2 of the Tramore Limestone Series of 


Wel 55. | BEDDED ROCKS OF COUNTY WATERFORD. 753 


the neighbourhood of Newtown Cove. It differs from any with 
which I am acquainted, and is not too imperfect for a partial specific 
diagnosis. 

The glabella is strongly convex and club-shaped, the anterior 
third forming the frontal lobe expanding suddenly to about double 
the width of the neck. There are three pairs of equidistant small 
deep pits indenting the sides of the narrow neck-like part of the 
glabella, and the faint occipital furrow likewise ends in a pair of 
similar pits. The anterior pair is situated just behind the point 
where the glabella widens into the frontal lobe. There are also 
three pairs of conspicuous equidistant large tubercles along the 
length of the glabella, the front pair being on the frontal lobe. 
Along the front edge of the glabella are four or five similar large 
conical tubercles projecting forward. No other tubercles exist on 
the glabella, but the surface is finely granulated. The axial furrows 
are wide and deep. 

The fixed cheek is imperfectly preserved, but is seen to be more 
than twice as wide as the glabella at its base, and strongly convex, 
bending downward and backward towards the genal angle. A 
distinct ridge runs outward close to the anterior edge of the fixed 
cheek, from the base of the frontal lobe of the glabella to the eye. 
Two large tubercles are seen in front of this ridge, and two similar 
tubercles lie in a line behind it parallel with the axial furrow. 
Another smaller one lies nearer the genal angle. No other tubercles 
are visible on the fixed cheek, but a fine granulation is present as 
on the glabella. 

The neck-furrow is broad though shallow, and the neck-segment 
is narrow, rounded, and tuberculated. 


MEASUREMENTS. 
mm. 
erbetin ot Rend -BielG yoo o.k .5.4,-.ceaesccsesacdeeanasoons 50 
Width (approximately) of the same .................. 10:0 
oo Of elabellat the base 2. .250:.5-2s2eseeses shoe 25 
SK ie, » across the frontal lobe ............ 50 


Affinities.—The club-shaped glabella and short pit-like furrows 
resemble Cybele brevicauda, Ang. but the eye-ridge and sparse 
tubercles on the glabella with the large anterior marginal tubercles 
recall C. coronata and C. rex. 


ENCRINURUS FALLAX, sp. noy. (Pl. XLIX, figs. 9-12.) 


There is an abundant small species of Hnerinurus occurring in 
Stage 3 of the Tramore Limestone Series, and also with much less 
frequency in Stage 2. This form was attributed to E. sexcostatus 
by Baily, but Salter * had declared previously that this species was 
not found in Ireland. So far as the Waterford area is concerned, 
Salter appears to be right, for this Encrinurus belongs to another 
species, as will be seen from the following description. 


a Mem. Geol. Sury. dec. vii (1853) No. 4, p. 5. 


754 MR. F. R.C. REED ON THE LOWER PaLmozoIc —[ Nov. 1899, 


Head-shield broadly semicircular in shape, strongly conyex from 
side to side and also from back to front. 

Glabella regularly convex, swollen, subcylindrical, slightly broader 
in front than at the base, but not inflated in front or overhanging 
the margin as in &. sexcostatus. Anterior end of glabella obtusely 
rounded. Neck-furrow at the base strong, slightly arched forward. 
Three pairs of short lateral furrows indent the sides of the glabella ; 
the basal furrows are the longest, and are slightly directed forward, 
marking off a pair of very narrow basal lobes not wider than the 
neck-ring. ‘The second pair of furrows is usually short, but some- 
times continued weakly over the surface of the glabella, curving gently 
backward so as nearly to meet the basal furrows, and thus faintly 
defining a pair of middle lateral lobes separated from each other by 
a space equal to about a quarter the width of the glabella. The 
anterior pair of furrows is very short, merely indenting the sides of 
the glabella, and they are situated at the same distance from the 
second pair as the latter are from the basal pair. 

The frontal lobe is about double the length of the anterior pair 
of lobes, and does not overhang them laterally. It is rounded in 
front, where it is encircled by a marginal furrow which runs into 
the deep and strong axial furrows. A narrow tuberculate, almost 


horizontal border is thus marked off sharply from the anterior end 


of the glabella, as in H. Seebachi, Schmidt, and a few other species. 
Where the marginal furrow meets the axial furrow a small deep 
pit is found on each side. 

The fixed cheeks are convex and much swollen, being elevated 
nearly as much as the glabella. They are produced backward, and 
strongly bent down towards the genal angles. 

The eye-lobe is large and elevated, standing up prominently from 
the cheek. 

The facial suture curves backward and outward from the front 
of the glabella to about the level of the second lateral furrow, 
where the eye is situated at a distance from the axial furrow equal 
to about the width of the glabella. From this point the facial 
suture bends sharply outward, and running nearly parallel to the 
posterior margin of the head-shield, cuts the outer edge immediately 
in front of the genal angle. 

The free cheek is triangular, with a rounded border marked off 
by a strong marginal furrow from the convex tuberculated inner 
portion, which rises steeply up to the tall conical eye borne on a 
short constricted stalk. 

The neck-lobe and segment are narrow and rounded, the latter 
widening a little towards the genal angles. 

The whole surface of the head-shield is ornamented with small 
tubercles, but on the fixed cheeks there are in addition a few of 
larger size; and three or four of such larger tubercles are noticeable 
on the free cheeks. 

The thorax is known only from two young individuals which are 
almost complete. These show twelve body-rings, with an axis mea- 
suring about one quarter the whole width of the thorax. The axis 


~ 


Vol. 55. | BEDDED ROCKS OF COUNTY WATERFORD. 755 


is convex and prominent; each ring has a median raised rounded 
ridge, ornamented with tubercles and furnished with a narrow flat 
articulating band on the anterior and posterior margins. A con- 
Spicuous nodule is seen on each side, as in Calymene Blumenbach. 
The pleural portions are gently convex, for the pleure curve down- 
ward beyond the obscure fulcrum. Each pleura is nearly straight 
to a point a little beyond the fulerum, but then it bends backward 
somewhat. The fulcrum is situated at a distance of about two-thirds 
the length of the pleura from the axial furrow. The surface of 
each pleura bears a median rounded tuberculated ridge, like the axis, 
with a narrow anterior and posterior articulating band extending 
out as far as the fulcrum. The free ends are bluntly pointed. 

The pygidium resembles in shape that of Z. sexcostatus, but it 
has only twelve to fifteen rings marked on the axis, and of these, 
usually the first nine or ten (but sometimes only the first four) 
are continuous across the axis as complete rings. The axis ends 
a short distance from the posterior end of the pygidium, tapering 
gradually backward to its bluntly-pointed extremity. 

There are five strong rounded pleure on each side, rather more 
strongly curved back than in F. seawcostatus. The sixth pleura is 
very short, closely pressed against the side of the axis, and often 
obscure. The first four pairs are large, distinct and prominent, 
possess no furrows, and curve regularly backward. The fifth pair 
is weaker, and runs nearly straight backward. ‘The sixth pair, as 
stated, is very weak and short. 

There are several large tubercles on each axial ring of the 
pygidium, with smaller tubercles ir regularly scattered between them, 
On the first pleura there are three or four large equidistant tubercles ; 
on the second two or three; on the third two; and on the fourth 
and fifth one or two. Salter (op. cit.) says that in &. sewcostatus 
the ribs are always smooth. 


MEASUREMENTS. 
(1) (2) (3) 
mm. mm. mm. 
Length of head-shield ......... 4:5 50 70 
Width of the same ......... 10-0 10:0 13:0 
Length of pygidium ......... 6:5 50 70 
Width of the same _......... 9-0 9-0 8:5 


Affinities.—Though this species is allied to H. sexcostatus by 
many characters, yet it shows several differences of some importance : 
(1) its glabella is not swollen in front, and does not overhang the 
front margin; (2) the lateral furrows of the glabella are different ; 
(3) the cheeks are tuberculated, not pitted; (4) the number of 
axial rings in the pygidium is less; (5) the pygidial pleuree curve 
back more strongly and are ornamented with tubercles; (6) the 
sixth pair of pleurz is nearly obsolete. 


MEGALASPIS, Sp. @. 


A small hypostome, 9 mm. long, in the Geological Survey Col- 
lection at Dublin, shows by its characters that it belongs to this 


756 MR. F. R. C. REED ON THE LOWER PaLmozoic [| Nov. 1899, 


genus (or subgenus). It comes from Stage 2 of the Tramore 
Limestones of Tramore. Its features are closely similar to those of 
M. limbata, Ang., from the Orthoceras-limestone,’ and it possesses 
the same shape, the posterior pair of nodules, the striated border, etc. 
of that species. But the central portion slightly widens in front 
and is not so distinctly marked off from the anterior wings. More- 
over, its whole surface is ornamented with curved striz, arched 
backward and parallel to the side-borders. 


Mueatasris, sp. y. 


In my collection there are some large parabolic pygidia without 
any trace of an axis, axial rings, or pleure. They are in an im- 
perfect state of preservation, but the surface is seen to be flattened 
and smooth, with a slightly excavated border which, beneath the 
crust, shows an ornamentation of concentric striz particularly 
strong on the upper and inner edge. The anterior margin of the 
pygidium is imperfect. The whole shape is rather more pointed 
and elongated than that of Asaphus gigas (De Kay) as figured by 
Salter, and the absence of all trace of an axis completely dis- 
tinguishes it. 

The estimated length of one specimen is 45 mm., and its width 
from 50 to 60 mm. 

This form is found in Stage 3 of the Tramore Limestones in 
Newtown Cove and at Dunabrattin (Geol. Surv. Coll.). The speci- 
mens from the last-named locality are in a somewhat better state of 
preservation, and are slightly more elongated, one measuring 52 mm. 
in length and the same in breadth. Angelin’s* Megalaspis rudis 
resembles this form in the absence of any trace of an axis and of 
any furrows. 

Associated with this form there is a head-shield which probably 
belongs to it. From the specimens, which are unfortunately imper- 
fect, we are able to judge that it much resembled A. gigas as figured 
by Salter. But the eyes are placed rather more forward, and the 
axial furrows behind them are quite wanting. ‘There is a fine 
specimen of the head, minus the free-cheeks, measuring 35 mm. in 
length, in the Geological Survey Collection from Dunabrattin, and 
the present author has one from Newtown Cove. 


Asapuus (PrycHopyer ?) Rapratvs, Salt. var. 


There are several specimens of pygidia in the Geological Survey 
Collection from the Tramore Limestones of Dunabrattin, labelled 
Ogygia, which agree in all their principal characters with Salter’s 
A, radiatus.* But they differ in being rather less transverse in shape, 
and in possessing nine instead of eight furrows on their pleural 


? Brogger, ‘Ueber die Ausbild. Hypost. skand. Asaphiden,’ Bih. t. Kong. 
Svensk. Vet.-Akad. Handl. vol. xi (1886) No.3 p.40. 

? Brogger, ‘ Die Silur. Etagen 2 u. 3,’ 1882, p. 77 & pl. xii, fig. 10. 

° Pal. Scand.’ 1854, p. 50 & pl. xxvii, fig. 5. 

* Monogr. Paleont. Soc. ‘ Brit. Trilob.’ p. 157 & pl. xviii, figs. 1-5. 


Vol. 55.] BEDDED ROCKS OF COUNTY WATERFORD. 757 


portions. The oblique striation which Salter figures does not 
extend so far inward from the margin, but reaches only to the tip. 
of the axis, and maintains the same width all round the sides. 
A specimen in my collection is from Stage 3, Newtown Cove. 
A. radiatus has been found inCounty Louth, as well as at Rhiwlas ; 
Salter (op. cit.) compares it with a Russian Ptychopyge described 
by Lawrow. 


AsapHus (PrYcHOPYGE) sp. 


A distorted and imperfectly-preserved pygidium from Stage 1 of 


the Tramore Limestones of Dunabrattin is of a broad semicircular 
shape, with seven or eight ribs onthe pleural portions, a conical axis 
of the same shape and relative length and distinctness as A. rectefrons, 
measuring about one quarter the “width of the pygidium at its front 
end, and extending for about two-thirds of its length, with seven or 
eight rings indicated on it. 

This form may be compared with Angelin’s Piychopyge lata.” 


Asapuus Haventoni, sp.nov. (Pl. XLIX, fig. 13.) 


An exceedingly well-preserved specimen of a pygidium from the 
Tramore Limestone Series (Stage 2) of Tramore, in the Geological 
Survey Collection at Dublin, shows certain peculiar features which 
render it necessary to create a new specific name. Its characters 
are as follows :— 

Outline broadly parabolic, gently convex from side to side, 
flattened from front to back, furnished with a rather broad concave 
depressed border. Surface smooth, unornamented. Anterior 
margin nearly straight, lateral angles not truncated. Axis marked 
only by a very slight curving forward of the margin, and by a weak 
depression on each side. A sharp raised ridge on each side of the 
axis runs from this depression obliquely outward and backward 
to the lateral border at an angle of about 15° to the front margin, 
limiting posteriorly the elongated triangular surface of the articula- 
tion at the lateral angle. This triangular facet is marked by a few 
faint irregular raised lines. Theridge becomes suddenly very weak 
on crossing the concave border, and is defined posteriorly by a deep 
furrow which ends at this border. 

At the posterior end of the pygidium the border is rather nar- 
rower than at the sides, and has a width of about one-fifth of the 
total length of the pygidium. It is everywhere markedly excavated 
and depressed below the central elevated, gently convex portion of 
the pygidium. A slight truncation and bending-up of the edge is 
noticeable directly behind the posterior end of the axis. Axis less 
than one-third the width of the pygidium, very depressed, only 
indicated near the anterior margin by a very faint independent con- 
vexity ; behind this it is entirely indistinguishable, being level with 
the general surface and without axial or transverse furrows. Its 
posterior end, however, is indicated in front of the concave border, 


1 « Pal. Scand.’ 1854, p. 55 & pl. xxxi, fig. 1. 


758 MR. F. RB. C. REED ON THE LOWER PALHOZOIC [Nov. 1899, 


the rounded tip being very faintly elevated. There is no trace of 
furrows on the pleural lobes. 


MEASUREMENTS. 
mm. 
hengthiof pysitiamas viens xdenaae dso sneremanermeede at 21:0 
Wadlihoiithie eam (<5 5 ahe oh ode anion oa ance cumece neers 36:0 
OL ISIS ab tue iromt OMG. costes eames meeee ne eaten: 13° 
Thenpth. Of the'sanie .61.. 01 Aaneeestetaeace <0 soemcutnenone 15:0 


Asaphus platyrhachis, Steinhardt,’ has a pygidium resembling 
that of A. Haughton in its weak convexity, in the relative width 
and the faintness of the axis, the marking of its posterior end, and 
the concavity of the border. But it differs in being elongated and 
not transverse in shape, and in possessing traces of ribs on the 


pleural portions. 


Irtanvus Davist, Salt. var. PSEUDOLIMBATUS Nov. 


A somewhat abundant species of Jl/enus occurring in Stage 2 of 
the Tramore Limestone Series, of which there are several rather 
imperfect specimens in the Geological Survey Collection at Dublin, 
shows a few features different from J. Davisi,’ to which it has been 
ascribed. The large eyes are nearer the posterior margin of the 
head-shield than in J. Davisz; there is a small median tubercle 
near the base of the glabella, as in J. lambatus, Linnarsson,? and the 
surface of the shell is finely punctate. 

There are ten body-rings as in J. Davisi, and the relative width 
of the axis and pleure and position of the fulcrum are as in that 
species. Pygidium similar in shape to that of J, Davisi, but with 
the lateral angles truncated. 

It is possible that this form really constitutes a distinct species, 


TRAMORIA PUNCTATA, gen. et sp. nov. (Pl. XLIX, figs. 14-16.) 


Portions of the head-shield of a peculiar trilobite occur with 
some frequency in Stage 3 of the Tramore Limestone Series. In 
the Geological Survey Collection at Dublin are the most perfect 
specimens that I have seen. ‘The characters are the following :— 

Head-shield semicircular, flattened, surrounded by a raised 
flattened border of equal width, ornamented with thread-like lines 
concentric to the margin. ‘The inner side of the border slopes down 
into the furrow which marks it off from the rest of the head-shield, 
and in this furrow lies a single series of nearly equidistant pits 
averaging about fourtoevery5mm. The genal angles are produced 
into flattened spines curving slightly inward and devoid of the 
furrow and pits, but ornamented with the concentric lines of the 


1 Steinhardt, Beitr. z. Naturk. Preussens, No. 3 ‘ Die in preuss. Gesch. gef. 
Trilob.’ 1874, p. 24 & pl. i, fig. 10; Pompeckj, ‘Die Trilobf. d. ost- u. west- 
preuss. diluv. Gesch.’ 1890, p. 82 & pl. v, fig. 7. 

2 Monogr. Palzont. Soc. ‘ Brit. Trilob.’ p. 194 & pl. xxix, figs. 10-16. _ 

3 «Om Vestergotl. Cambr. o. Silur. Aflagr.’ Kong. Svensk. Vet.-Akad. Handl. 


vol. viii (1869) No. 2, p. 77 & pl. ii, fig. 43. 


Vol. 55. | BEDDED ROCKS OF COUNTY WATERFORD. 759 


border. The glabella, which is slightly raised above the general 
surface of the head-shield and is nearly three-quarters its length, 
is of a peculiar shape, being much expanded between the large 
embracing eyes and contracted in front of them. In front of the 
eyes it is broadly conical, with an obtusely-rounded anterior end 
situated a short distance behind the marginal pitted furrow. 
Between the eyes it is transversely oval, being twice as wide as in 
front of them, and the width of this portion is about twice the 
length. Its sides are closely embraced by the large semiannular eyes. 
A straight neck-furrow parallel to the posterior margin of the neck- 
ring marks off the glabella at its base. A pair of very short 
oblique furrows, in some specimens bent round into a V-shape, 
indent the surface of the posterior portion of the glabella at a 
distance from the neck-furrow equal to about one-fifth the whole 
length of the glabella, and separated one from the other by a space 
equal to about one-third its basal width. There are no other dis- 
tinct furrows on the surface of the glabella, but it is ornamented by 
fine, closely-set, transverse undulating lines arched forward in the 
centre and on each side, 

The neck-ring is broad, flat, and parallel-sided. ‘It is marked by 
several thread-like lines, gently curved forward in the centre. 

The large semiannular eyes, embracing the hinder part of the 
glabella, rest with their base on the neck-furrow and against the 
neck-segment, and then curving forward extend half the length of 
the glabella. ; 

The facial suture can be satisfactorily traced only in front of the 
eyes, and from the anterior end of the glabella it is seen to strike 
off obliquely outward so as to cut the front margin of the head- 
shield. The distance apart of the facial sutures at their point 
of section of the margin is about equal to the width of the broadest 
portion of the glabella. 

The free cheeks are flat and unornamented, except for a few 
obliquely-directed raised lines running back from the marginal 
furrow for a short distance. | 

The under-surface of the border (doublure) of the head-shield is 
marked by a few concentric strie. There is a transverse sinuous 
suture running from the glabella to the outer margin of the head- 
shield, the interpretation of which is doubtful. 

Body-rings and pygidium unknown. 


MEASUREMENTS, 

mm, 

enathy of ead sail ooo ce. sinines ob sin on ons etoaatheadas tae eee cov 14-0 
Width of the sama “i.255: jin hk. ftdsek de Be ee res Oe 30:0 
Bish ath of MIVA: -.h. cine LAM dd. eked ubboo tien deadeeieh esse behest 90 
Width of the same between the eyes ............ceccesececnesececeees 14-0 
3 ii HW Frodt'of thie Gyes' weiss sensi’ oceilsad cadens 8:0 

» along the neck furrow «00.01... 0c0eeccceceesetees 3:0 

jy) OE ALOU THREE sem, 25). AW Oras Pek oben Wel Hdaback adctaneeuts. 20 


Affinities.—It is difficult to assign this peculiar form to any 
known genus. It seems to be allied to Remopleurides by the large 


760 MR. F. R.C. REED ON THE LOWER PALHOZOIC [Nov. 1899, 


embracing eyes, the tongue-like projection of the glabella, and the 
linear ornamentation; but the pitted marginal furrow, raised border, 
and the divergent anterior branches of the facial suture are not 
found in any species of that genus. 

The course of the facial suture reminds one somewhat of that in 
Proetus, which also has some species with enormously developed 
eyes closely applied to the glabella. The pits in the marginal 
furrow recall the Cambrian genus Huloma. 

It seems therefore necessary to institute a new generic as well as 
specific name for this fossil, and it may be termed Tramoria punctata, 


OrtTHIS aRGENTEA, Hisinger. 


The species of Orthis which occurs in great abundance in the 
sandy shales of Newtown Head was named by the officers of the 
Survey O. elegantula. M‘Coy' had previously assigned it to Pander’s 
species O. parva, and Salter * called it O. striatula, Conrad. David- 
son® considered Salter’s specimens to belong to O. testudinaria. Miss 
Elles, who has kindly examined numerous specimens from this 
locality, identifies it with Hisinger’s * species O. argentea, and thus 
confirms the opimion which I hold. The species in Sweden is a 
very variable one, but is characteristic there’ of beds which are 
equivalent to our Hartfell, being particularly abundant in the lower 
part and marking a zone at the top of the Dicranograptus-shales. 
In Wales * it has been recognized on a similar horizon, and here we 
find it associated with some characteristic Llandeilo fossils. In 
these specimens the lateral ribs do not curve up so much towards 
the hinge-line, and in this respect resemble Lindstrém’s figures of 
the species, but differ from the Welsh form. 


Orruisina cf. sauamata, Pahlen. 


A portion of a valve from Stage 2, Tramore Limestone Series, 
Newtown Cove, shows the peculiar ornamentation described and 
figured by Pahlen’ in O. squamata of the Kchinospherite-lime- 


stone.® 


Orruis (Onruisina ?) cRIsPA, M‘Coy. 


Common in Stage 2, Tramore Limestone Series. Some specimens 
show internal characters resembling Orthisina, and the ornamenta- 
tion of the valves is closely similar to that of Orthisina squamata and. 


1 M‘Ooy, ‘Brit. Pal. Foss.’ 1855, p. 221. 

2 Salter, Mem. Geol. Surv. vol. iii, 2nd ed. (1881) p. 545; ‘Cat. Cambr. Sil. 
Foss. Woodw. Mus.’ 1873, p. 38. 

3 Monogr. Paleont. Soc. ‘ Brit. Silur. Brach.’ vol. iii, p. 226. 

4 Hisinger, ‘Leth. Suec.’ 1837, p. 72 & pl. xx, fig. 15; Lindstrom, ‘ Fragm. 
Silur.’ p. 26 & pl. xiv, figs. 12-15. . 

6 Tullberg, ‘Skanes Graptoliter I,’ Sver. Geol. Undersokn. Ser. C, No. 50 
(1882); Linnarsson, ibid. No. 31 (1879) p. 20. 

6 Marr & Roberts, Quart. Journ. Geol. Soc. vol. xli (1885) p. 476. 

7 «Monogr. balt.-silur. Arten d. Brach.-Gattung Orchisina,’ Mem. Acad. Imp. 
Sci. St. Petersb. vol. xxiv (1877) No. 8, p. 20 & pl. ii, figs. 1-4. 

8 Schmidt, Quart. Journ. Geol. Soc. vol. xxxviii (1882) p. 520. 


Wol. 55.] BEDDED ROCKS OF COUNTY WATERFORD. 761 


allied forms. Orthisina is a characteristic genus of the Lower 
Ordovician of Russia and Scandinavia.1 The Waterford form of 
O. crispa is very variable, and possibly comprises more than one 
species. A subquadrate, subglobose variety from Knockmahon, with 
flattened lateral angles and almost obsolete concentric markings, is 
figured by Davidson.? Another with a weak sulcus in the ventral 
valve and considerably flattened (Davidson, op. ct. fig. 8) has a 
finer ornamentation than is usual in the Tramore specimens 
(Davidson, op. cit. fig. 5). 


PoRAMBONITES INTERCEDENS, Var. FILosA (M‘Coy). 


Davidson * discussed this species at length, and mentioned its 
sole undoubted places of occurrence in the British Isles as Duna- 
brattin, Tramore, and Knockmahon. I have found it in consider- 
able abundance in the lower portion of the Tramore Limestones 
on the west side of Dunabrattin Head, and there are specimens 
in the Geological Survey Collections at Dublin from the beds 
near Tramore. The specimens from Wrae Quarry, Peeblesshire, 
were considered doubtful by Davidson. P. intercedens, together 
with several others of Pander’s* species of the genus, was put by 
Eichwald’ into Schlotheim’s species P. wquirostris, but neither 
Davidson nor De Verneuil considered Hichwald’s synonymy correct. 
It is, however, clear that Davidson did not use the specific name 
in the limited sense in which Pander had done, as a comparison 
of the Irish specimens with Pander’s figures at once shows. 
Schmidt ° records P. intercedens, Pander, from the Orthoceratite- 
limestone (Vaginatenkalk), B3; but itis not stated whether he uses 
the name in the extended sense. P. wquirostris (Pander), which 
may be compared with our form, is stated by the same author’ to 
occur in the Echinospheerite-limestone, C1. 

Brogger ° thinks that the Irish form may be a separate species, 
but the variety of P. intercedens (Pander) which he figures from 
the Orthoceras-limestone bears an extremely close resemblance to 
the specimens from Dunabrattin Head. M‘Coy’s® type-specimen, 
which I have examined, came from the ‘schists at Knockmahon, 
Tramore, County Waterford.’ There is a valuable discussion of 
the affinities of the genus in a paper by Neetling,'° and in Hall & 
Clarke’s*' great work on the Brachiopoda. 


1 Frech, ‘ Leth. Geogn.’ pt. i, vol. ii (1897) p. 73. 
2 Monogr. Palzont. Soc. ‘ Brit. Silur. Brach.’ vol. iii, p. 256 & pl. xxxviii, 


fig. 6. 
3 Jhid. p. 195. 
4 « Beitr. z. Geogn. Russ. Reich.’ 1830, p. 95. 
5 «Leth. Ross.’ 1860, p. 794. 
6 «Rev. Ostbalt. Silur. Trilob.’ pt. i, Mem. Acad. Imp. Sci. St. Petersb. 
ser. 7, vol. xxx (1881) No. 1, p. 21. 
7 Guart. Journ. Geol. Soc. vol. xxxviii (1882) p. 521. 
8 « Die Silur. Etagen 2 u. 3,’ 1882, p. 50 & pl. xi, figs. 1 a—d. 
9 «Syn. Silur. Foss. Irel.’ 1846, p. 39 & pl. iii, fig. 28. 
10 Zeitschr. Deutsch. Geol. Gesellsch. vol. xxxv (1883) p. 355. 
11 Paleont. N. Y. vol. viii (1894) Brach. pt. ii, p. 225. 


Q.3.G.8. No. 220. 3D 


762 MR. F. R. C. REED ON THE LOWER PALHOZOIC [Nov. 1899, 


Coscrnium cf. proavum, Eichwald. 


There are several specimens in the Dublin Collection named Nebuli- 
pora from the Tramore Limestones of Tramore which are closely 
allied to Kichwald’s Cosciniwm proavum of the Russian Orthoceras- 
limestone.’ The oval or subcircular fenestrules in the flabelliform 
polypary are separated by celluliferous portions of six or seven rows 
of cells measuring nearly twice the diameter of a fenestrule, and thus 
the fenestrules are more distant one from the other than in the 
Russian form, specimens of which I have examined as well as the 
original figures and descriptions. 


Hyouirues cf. striatus, Eichwald. 


Not uncommon in the Raheen Shales at Newtown Head, and 
comparable to Hichwald’s H. striatus from the Orthoceras-lime- 
stone.” Schmidt’ quotes it from the Brandschiefer (Kuckers Shale), 
C2. Kichwald mentions that there is a variety of the species with 
the longitudinal strie fine and close together, and ours agrees with 
this description. It is certainly distinct from any described British 
species. 


MEASUREMENTS. 
mm. mm. 
Teng t he car eiericanciticsamaesitasencesest 10 13°5 
Width at proximal end ............ 3 1 AED 


Guiyptocystis cf. penNIGERA (Kichwald), 


The specimen described by M‘Coy * as Acanthalepis Jamesii, and 
believed by him to be a fish-scale, is in truth the plate of a cystidean. 
This fact was noted by me when I examined the type in the Dublin 
Museum in 1896; but I have subsequently found that so far back as 
1860 Eichwald ’ had assigned it to this group of echinoderms, and 
compared it with his species Glyptocystis (= Cheirocrinus) penni- 
gera from the Orthoceratite-limestone. Schmidt° described this 
species more fully, and recorded it from the uppermost part of the 
Orthoceratite-limestone and the ‘ Brandschiefer.’ More recently’ 
he mentions it as occurring in the Kuckers Shale (Brandschiefer), 
C2, in association with Echinosphera aurantium, etc. Heeckel ® 
has still more recently figured and redescribed it. 

The original Irish specimen was found at Newtown Head in the 
Raheen Shales, and I have myself obtained a plate of the species 
from the same locality. There are several specimens of it in the 
Geological Survey Collections. 


‘Urw. Russl.’ pt. ii, p. 44 & pl. i, fig. 5; ‘Leth. Ross.’ 1860, p. 398. 
‘Leth. Ross.’ 1860, p. 1046 & pl. xl, fig. 15. 
Quart. Journ. Geol. Soc. vol. xxxviii (1882) p. 521. 
‘Syn. Silur. Foss. Irel.’ 1846, p.'7 & pl. i, figs. 1-2. 

° *Teth. Ross.’ 1860, p. 646 & pl. xxxii, fig. 1. 

6 «Neue u. wenig bek. Balt.-Silur. Petrefacten,’ Mem. Acad. Imp. Sci. St. 
Petersb. vol. xxi (1874) No. 11, p. 15 & pl. i, figs. 7-12, pl. ii, figs. 1-3. 

7 Quart. Journ. Geol. Soc. vol. xxxviii (1882) p. 521. 

& «Die Amphorideen u. Cystoideen: Beitr. z. Morph. u. Phylog. d. Echinod.’ 
Festschr, z. 70ten Geburtstage v. C. Gegenbaur, vol. i. (1896) p. 150 & pl. iv. 


As { 


Pod 


Vol. 55.] BEDDED ROCKS OF COUNTY WATEREORD. 763 


GuypTocystis sp. 


This form, from Stage 3 of the Tramore Limestone Series, was 
previously 1 compared by me with Gl. Logani (Billings), but the 
examination of more material shows that this was an error. 

The angular spaces between the strong ribs radiating from the 
elevated centre of the conical plate to the angles are occupied by 
regular radiating rows of minute granules separated by fine linear 
strie parallel to the ribs. This peculiar ornamentation is particu- 
larly well seen in an external cast of a six-sided plate bearing half 
a pore-rhomb with the characters rather of Gl. gigantea (Leucht.)’ 
than of Gl. pennigera. 


Monticutrpora (DieLorryeA) PETROPOLITANA, Pander. 


Characteristic of Stage C in Russia. Abundant in Stages 1 & 2 
of the Tramore Limestones. Milne-Edwards & Haime* described 
it from these at Tramore, Knockmahon, and Ballydouane. 


V. Prrrotocicat Norges on THE CoNTEMPORANEOUS 
Vortcanic Rocks. 


The mode and place of occurrence of these rocks have been 
described above, and it will have been noticed that all are of a 
felsitic character. Microscopically they show some interesting 
features. Perlitic and nodular structures are not uncommon. 
Thus, at Raheen, near the top of the bedded series, a light grey tough 
felsite (see fig. 1, D, p.722) [6 w] is found to be traversed by well- 
marked perlitic cracks filled with clear transparent material, and 
small ragged crystals and microlites of felspar are observable with 
minute, circular, clear spots in the groundmass. With crossed 
nicols, the groundmass is seen to be cryptocrystalline and almost 
isotropic in parts; but it is mainly composed of innumerable 
microspherulites closely packed together and giving a black cross. 
In the perlitic cracks they are especially distinct and sharp, 
and these, at any rate, must be regarded as secondary in origin. 
Some nests and veins of angular grains of clear non-spherulitic 
quartz also are visible, and the few small felspar-microlites are 
arranged in parallel lines of flow. There are a few small, twinned, 
lath-shaped crystals of plagioclase-felspar with very low angles of 
extinction, which probably are oligoclase. 

The pale grey felsite [7 w] underlying this (fig. 1, E, p. 722) 
shows perlitic structure with great distinctness on weathered 


1 Geol. Mag. 1897, p. 511. 

2 Schmidt, Mem. Acad. Imp. Sci. St. Petersb. ser. 7, vol. xxi (1874) No. 11, 
p. 23 & pl. ii, figs. 11 & 12. 

* Dybowski, ‘ Die Chetetide d. Ostbalt. Silur-Form.’ 1877, p. 24, & pl. i, 
figs. 4 & 5; Nicholson, ‘ Struct. & Affinities of the Genus Monticulipora,’ 1881, 
p. 156; poe & Frech, ‘ Leth. Geognost.’ pt. i (1880-1897) p. 473 & pl. iii, 
figs. 1 a-0. 

+ Monogr. Palzont. Soc. ‘ Brit. Foss. Corals, 1854, p. 264, & references to 
foreign literature. 

3Dn2 


764 MR. F. R.C. REED ON THE LOWER PALZOZOIC _—[ Nov. 1899, 


surfaces, in connexion with a kind of concretionary structure 
intimately related to a series of rectilinear cracks traversing the 
rock in all directions, and not arranged with any regularity. In 
each of the areas thus enclosed is a series of closely-packed 
concentric perlitic cracks, often with subsidiary systems of con- 
centric cracks. The whole appearance of the rock reminds one, on 
a minute scale, of the spheroidal jointing in granite and other rocks. 
With crossed nicols the perlitic structure becomes invisible, and the 
groundmass is seen to consist of an indistinct microcrystalline 
aggregate or irregular mosaic, with only a few microspherulites and 
felspar-microlites. In some places the blurred-mosaic structure is. 
less evident, and the groundmass appears to consist of crowded 
groups of incipient or ill-developed microspherulites. There are 
no phenocrysts visible. 

This rock has been analysed for me in the University Laboratory, 
Cambridge, by Messrs. H. O. Jones & C. Robinson, with the: 
following results :—- 


Per cent 

DIO! ICR Pe erences eee canteen duane ee 78:12 
ALO, ALUMINA ie, ccsecevesorsaeesacecneedae 13°61 
Fe,O, Iron Sesquioxide  .................. 1-08 
CaO Cinte. e cc sense se nhoeme se vaac tess 2°04 
Mic @. Ma onesia Mast. sedactecups he acer ss “71 
KOT sPobashe Mee Maan uieGes sadeeae 2°67 
aR O) SOU dese penducesnee.nncaneeaeners “24 
TL OF INVOICE oes oats: cent Jost seteceoe “75 

99°22 


This analysis shows a type distinct from any described‘ from the: 
Waterford area, particularly in the proportion of the potash to the 
soda. 

Another felsite [568] [13 w] from Newtown Head shows under 
the microscope a minute distinct mosaic of irregular quartz-grains,. 
each containing many inclusions. Locally this structure appears 
to be more of a granophyric than of a micropoikilitic nature. 
Nests of clear granular quartz occur, probably representing original 
vesicles, and one or two porphyritic plagioclase-felspars are also- 
distinguishable. 

A pale greenish felsite [501], from the same series, showing 
in the groundmass loosely-packed clear circular spots which, with: 
crossed nicols, are seen to possess no radial structure but to enter 
merely into the general granular character of the groundmass, 
seems to be a variety of the nodular felsites which are common at 
Raheen. ‘The nodules are frequently as large as peas, and stand 
out on a weathered surface; but sometimes [14 w], under the 
microscope, they give no clear indication of their presence. 

In another case [502] they are visible under the microscope, 
in ordinary light, as circular or slightly irregular areas free from. 
the semi-opaque microlites, granules, and dust which are aggre-- 
gated round their margins, and scattered less thickly throughout 


1 Hatch, Geol, Mag. 1889, p. 545 & references. 


Volt 55. BEDDED ROCKS OF COUNTY WATERFORD. 765 


the groundmass. These clear areas, representing sections of the 
nodules, frequently coalesce [502] [22 w], and are often crowded 
with clear transparent felspar-microlites and a few needles of apatite. 

A micropoikilitic or granophyric structure [14 w] [502] [15 w] 
[22 w] is not uncommon in the groundmass, and occasionally 
[22 .w]is of coarser texture in the nodules. The latter are also 
sometimes [22 w] marked by a central, clear, rounded quartz-grain 
which does not seem to be of secondary origin. In one case [21 w] 
the nodules are outlined by a distinct narrow ring of clear angular 
quartz-grains. 

The analysis of one of these nodular felsites [22 w] was carried 
out for me in the University Laboratory, Cambridge, by Messrs. 
H. O. Jones & C. Robinson :— 


Per cent. 

SiO) | MOUNGAy iside-wapeescnees on ss suddsonistel 75°70 
AO) POA WAMU chateaus eo anna ieenclsaaeeenne 12°58 
Bes Ol Tron SesqulOxide ¢7..00.. 0000. sever 1-72 
CARE PIAS ian a8 oth ocak aecice,« alee seo tea 1:55 
INia@) Ea estan Va... Saco ce scacwere. west “70 
iO) SPotasn %..205. Pe diascauis Sata dutsa ca meee 4:50 
INO SSOC a fed itecs dee tinn atesnanhansacsee ee 1:30 
EEO, Water si iiesee. MR ee nen 1:23 

99°78 


This analysis bears a remarkable resemblance to that of the 
Tardree rhyolite quoted by Teall,! which is as follows, differing 
chiefly by the smaller amount of alumina and lime, and the absence 
of magnesia :— 


Per cent 

RO MSEC eh eh stat oo wcuis nalewiennia anurans tame 76-4 
A OP EN Minnis | ys dbans dndtinwe ade beet ete 14:2 
HesO; ron) Sesquioxdeys.. sceiacdnensssetg 16 
CO MARC ag ae seis newiapeet soa se san So Cota 6 
BES OE ONSEN pose sae ssominesnatewene aes anand ae 4:2 
Na OES OMe ote atiodn ode sasocktaoanosrenwes 18 
EON IW ations 248i coe. elves ed phuaessecs 15 

100°3 


The Tramore felsites belonging to the Carrigaghalia Series mostly 
contain porphyritic felspars [13] [626], probably of andesine; but 
in some cases [54 w] [80] phenocrysts are almost absent. Mono- 
clinic felspars are occasionally present [626], and porphyritic 
quartz-crystals as well [13]. The groundmass is generally micro- 
crystalline, with varying degrees of coarseness, and rarely [567] is 
it eryptocrystalline. Granophyric and porphyritic quartz-pheno- 
erysts, similar to those described in the Fishguard felsites,* are 
noticeable in some slides [626], and microperthitic structure in 
the felspar-crystals is occasionally visible [13]. Lines of flow and 
banding are also present in some cases [54]. 

The tuffs in the Raheen Series are composed mostly of fragments 


«Brit. Petrogr.’ 1888, p. 348. 
2 Quart. Journ. Geol. Soe. vol. li (1895) p. 165. 


766 MR. F. BR. C. REED ON THE LOWER PALHOZOIC [Nov. 1899, 


of felsites with chips of slates, etc., embedded in a fine paste, which 
with crossed nicols breaks up into an irregular granular aggregate 
[18 w] [610] [611]. Those in the Carrigaghalia Series are of very 
finely powdered materials and frequently calcareous, but call for 
no further description [53 w] [644]. 


VI. CorRELATION oF THE Rocks oF THE WATERFORD Coast 
WITH THOSE OF OTHER AREAS. 


The exact stratigraphical horizon of these beds has always been 
a disputed point. Jukes’ speaks of the limestone at Tramore as 
resembling the Bala Limestone of North Wales. Salter,” in de- 
scribing trilobites from the Newtown Head sandy shales (Raheen 
Shales), speaks of these beds as Llandeilo Flags, but with regard to 
those near Tramore calls them simply Lower Silurian. Jukes & 
Haughton,’ and Kelly,’ compared the beds on paleontological 
grounds to the Bala of England and Wales. Inthe Memoir of the 
Geological Survey of Ireland® the beds are termed Bala, but Baily 
considered that several horizons were represented. Salter’ in 
1864-65 described the species of Amphion from Tramore as occur- 
ring in Caradoc Slate, and the Barrandia from Newtown Head as 
occurring in Llandeilo Flags. Subsequently,* in his list of Irish 
fossils in the Woodwardian Museum, he termed the Waterford beds 
Lower Bala, noting that both Middle and Lower Bala appeared to 
occur at Newtown Head. Kinahan”® correlated all the Waterford 
fossiliferous beds with the Bala: and Caradoc, including them all in 
his ‘ Ballymoney Series.’ The occurrence of Glenkiln Shales with 
some of the typical graptolites was noted by Lapworth,” but Baily* 
had previously determined many of the species. Davidson,” in 
describing various brachiopoda from Newtown Head, Tramore, and 
Dunabrattin, calls the beds in which they occur Caradoc. Messrs. 
McHenry & Watts'* in their guide-book say that the graptolites 
at Tramore indicate the Llandeilo age of the black shales, etc., and 
that the limestone is ‘ approximately equivalent to that of Llandeilo.’ 
Sir A. Geikie** speaks of the Tramore Limestones as ‘ calcareous 
bands full of Bala fossils.’ 

The Tramore Limestones have been compared on pale- 


1 Journ. Geol. Soc. Dubl. vol. v (1852) p. 147. 

2 Mem. Geol. Surv. dec. vii (1853) pl. vi, p. 4. 

3 Ibid. pl. viii, p. 6. 

4 Trans. Royal Irish Acad. vol. xxiii (1858) p. 565. 

5 Journ. Geol. Soc. Dubl. vol. viii (1860) p. 251. 

6 Explan. Sheets 167, 168, 178 & 179 (1865) pp. 9, 23. 

7 Monogr. Palzont. Soe. ‘ Brit. Trilob.’ pp. 82, 140. 

8 «Cat. Camb. Silur. Foss. Woodw. Mus.’ 1873, p. 38. 

‘Geol. of Irel.’ 1878, pp. 27, 49. 

10 Ann. Mag. Nat. Hist. ser. 5, vol. iv (1879) p. 424. 

11 Quart. Journ. Geol. Soc. vol. xxv (1869) p. 158. 

12 Monogr. Paleont. Soc. ‘ Brit. Silur. Brach.’ vol. iii, pp. 51, 196, ete. 
13 «Guide to Collects. of Rocks & Foss. Geol. Surv. Irel.’ 1895, pp. 82 & 112. 
14 ¢ Ane. Vole. of Gr. Britain,’ vol. i (1897) p. 248. 


© 


Vol. 55.] BEDDED ROCKS OF COUNTY WATERFORD. 767 


ontological grounds! with the Balcletchie Shales of Scotland, but our 
knowledge of the fauna of the latter is very incomplete. It appears 
meanwhile probable, in the light of my recent work, that the Tramore 
Limestones mainly represent beds of a lower horizon than the 
Balcletchie Shales. The latter contain Hartfell graptolites, but the 
former are overlain by beds containing a general Glenkiln facies. 
Thus we may have to regard the few Tramore Limestone species 
in the Scotch area as merely the survivors of a migration from an 
adjoining area. In a similar way the Cystideans and Chasmopes 
of the Upper and Middle Bala of the Lake District and Wales are 
looked upon by Mr. Marr? as the surviving representatives of an 
earlier Scandinavian fauna which migrated from its old home. 

In the Waterford area, the difficulty arising from the fact that these 
graptolitic Glenkiln shales were seen to overlie beds containing what 
was held to be a Bala fauna probably led to the idea that the same 
principles of classification of the beds as those employed in other parts 
of Great Britain were not here applicable. Kinahan in one place’ 
says :—‘ The groups of fossils indicative of the age of the English 
Silurians are to some extent mixed up together in the Irish rocks, 
on which account they are not in Ireland a reliable test of the age 
of the rocks.’ Elsewhere* the same writer says :—‘ In the rocks of 
the Ballymoney Series the assemblage of fossils is to be compared 
with that of the Bala rocks, but Caradoc fossils are not uncommon ; 
while whenever black shales occur, no matter on what horizon, 
they nearly always contain fossils of Llandeilo type.’ 

The graptolitic shales and associated beds forming the Carrig- 
aghalia Series correspond paleontologically with the Dicrano- 
graptus-shales of Wales, which, as described by Messrs. Marr & 
Roberts’ and Misses Crosfield & Skeat,° rest on the Llandeilo Lime- 
stone. We might suppose that the underlying Tramore Limestones 
would correspond closely with the latter, but such is not the case ; 
the faunas are completely different. The Didymograptus-shales have 
not been identified in the Waterford area, though on the opposite 
side of St. George’s Channel, in South Wales, they underlie the 
Llandeilo Limestone. It may be urged that the ‘ Tramore Slates 
may represent them, and this is possibly the case, but there is no 
paleontological evidence as yet in support of this view. 

In Sweden, below the Cenograptus gracilis-zone (which is at the 
base of the equivalent of our Glenkiln Shales), comes the Orthoceras- 
limestone down to the top of the Ceratopyge-kalk.’ Though the 
term Orihoceras-limestone is used with somewhat different signifi- 
cation and comprehensiveness by different authors and in different 


1 Geol. Mag. 1897, p. 510. 

2 Quart. Journ. Geol. Soe. vol. xxxvili (1882) p. 325. 

8 Journ. Roy. Geol. Soc. Irel. vol. v (1878) p. 120. 

4 «Geol. of Irel.’ 1878, p. 25. 

5 Quart. Journ. Geol. Soc. vol. xli (1885) p. 476. 

6 Ibid. vol. lii (1896) p. 523. 

7 Tuilberg, Sver. Geol. Undersokn. Ser. C, No. 50 (1882); G. L. Elles, Quart. 
Journ. Geol. Soe. vol. liv (1898) p. 525. 


768 MR. F. R. C, REED ON THE LOWER PALZOZOIC [Noy. 1899, 


parts of Scandinavia,’ yet the above definition serves our purpose 
for comparison. The uppermost part of the Orthoceras-limestone 
is called the Cystidean Limestone, which is partly equivalent to the 
Kchinospheerite-limestone C1 of the Russian Baltic provinces.? 
Below this comes the main mass of the Orthoceras-limestone, 
which in Russia is more or less represented by the ‘ Vaginatenkalk ” 
B 3 and Glauconite-limestone B2. The fauna of the Tramore Lime- 
stones shows some remarkable points of resemblance with that of 
the upper part of the Orthoceras-limestone. Thus the characteristic 
genera Porambonites, Amphion, and Gilyptocystis are common to both. 

The subgenus of Phacops called Pterygometopus, represented in 
the Waterford area by Ph. Jamesu, Ph. Brongniarti, Ph. truncato- 
caudatus, and Ph. Bailyi, and in Russia by such species as Ph. 
sclerops, Ph. trigonocephata, is also a typical and abundant form. 

As regards species, the following are characteristic of both 
areas :—Monticulipora petropolitana, Porambonites  intercedens, 
Ampyx mammillatus, with the more widely distributed forms 
Stropheodonta imbrex, Rafinesquina deltoidea, Orthis (Platystrophia) 
biforata, Orthis calligramma, Plectambonites sericea.* To the exist- 
ence of allied species some foreign paleontologists have previously 
drawn attention. Thus Schmidt* compares his Phacops trigono- 
cephala from Stage C1 with Phacops Brongniarti ; Holm’ compares 
Menus Esmarki, Schlotheim, with Iilenus Baily, Salter.® 

I am able further to mention the following additional closely 
allied or representative species :— 


Asaphus rectifrons, Portl.—A. expansus and allies. 

Amphion benevolens, Salt.—A. Fischeri, Hichw. 

Agnostus agnostiformis, M‘Coy—A. glabratus, Ang. 

Chetrurus gelasinosus, Portl.—Ch. exsul, Beyr. * 

Ch. sp.—Ch. perlongus, Broge. 

Polypora assimilis, Lonsd. (?)— Polypora furcata, Hichw. 

Cybele tramorensis, Reed— Cybele coronata, Schmidt. 
"Barrandia Portlockti, Salter— Ogygiocaris dilatata, var. Sarsi, Ang. 
8 Pseudocrania divaricata, M‘Coy—Pseudocrania depressa, Kichw. 


Several Waterford species are also comparable with Scandinavian 
or Russian forms :— 

Ampy«x cf. Volborthi, Schmidt. 

Ampyx cf. Portlocki, Barr. 

Orthisina ef. sgwamata, Pahl. 

Cosciniwm ef. proavum, Kichw. 


1 Nathurst, Sver. Geol. Undersdékn. Ser. Ba, No. 4 (1884); Moberg, Sver. 
Geol. Undersokn. Ser. C, No. 109 (1890) p. 18. 

2 Schmidt, Quart. Journ. Geol. Soc. vol. xxxviii (1882) p. 521. 

3 Schmidt, ‘ Untersuch. ib. d. Silur-Form. v. Ehst. N.-Livl. u. Gisel,’ Archiv 
f. Naturk. Liv-, Ehst- u. Kurlands, vol. ii (1861) p.1; & Quart. Journ. Geol. 
Soc. vol. xxxvili (1882) p. 514. 

4 «Rey. Ostbalt. Silur. Trilob.’ pt. i, Mem. Acad. Imp. Sci. St. Petersb. ser. 7, 
vol; xxxi(1681)| No. pacle 

5 Ibid. pt. iii, ser. 7, vol. xxxiii (1886) No. 8, p. 53. 

6 Monoer. Palzxont. Soc. ‘ Brit. Trilob.’ p. 192. 

7 Frech, ‘ Leth. Geogn.’ pt. i, vol 11 (1897) p. 91 footnote. 

8 Eichwald, ‘Silur. Schichtensystem n Ehst.’ 1840, pp. 170 & 171; von Huene, 
Neues Jahrb. 1899, vol. i, p. 138 & pl. xii. 


Vol. 55.] BEDDED ROCKS OF COUNTY WATERFORD. 769 


An unexpected resemblance in the facies of the fauna of the 
Tramore Limestones to that of the upper part of the Orthoceras- 
limestone is thus indicated. 

It seems therefore that Stages 2 & 3 of the Tramore Limestones 
may be especially compared with the Echinospherite or Cystidean 
Limestone, and the Kuckers Shale C2 in Russia. Stage 1 may 
possibly include beds as low as, or lower than, the Megalaspis gigas- 
zone (=B:3 ‘ Vaginatenkalk,’ Russia). 

With regard to the Raheen Shales of Newtown Head, the 
abundance of Orthis argentea enables us to compare them with the 
Orthis argentea-zone in South Wales, which comes at the top of 
the Dicranograptus-shales.1_ We find in them such characteristic 
Llandeilo fossils as Calymene duplicata and Bellerophon perturbatus. 
We thus feel safe in placing these beds above the graptolitic shales 
of the Carrigaghalia Series, though possibly some of the felsites etc. 
of the top of that Series at Tramore may belong to this higher 
horizon. But in addition to some British forms there are other 
species peculiar to the beds, and others suggesting a Scandinavian 
or Russian affinity, as in the case of the Tramore Limestones. 
Especially interesting is this latter group, which comprises the 
species Ampyx mammuillatus, A. costatus, Orthis argentea, Cybele 
ef, rex, Hyolithes cf. striatus, and Glyptocystis cf. pennigera. 
Harpes Flanagani is allied to H. Spasskii, and Remopleurides Port- 
locki, sp. nov., to R. nanus, Leucht. All the foregoing species are 
specially characteristic of Stage C of Russia? (which includes the 
Kchinospherite-limestone Ci and the Kuckers Shale C2), or of the 
Scandinavian Cystidean Limestone,’ Lower Chasmops-limestone, 
Beyrichia-limestone, and part of Tullberg’s Middle Graptolite-shales. 
Marr* considered the Cystidean Limestone as partly equivalent to 
the British Lower Bala (=Llandeilo). It seems that we may 
especially compare the Raheen Shales with the upper part of 
Tullberg’s’ Series E of the Middle Graptolite-shales, on account of 
the abundance of Orthis argentea and its association with species 
of Ampyx, Trinucleus, and Cystideans. 

There are a few fossils in the Raheen Shales which usually are 
found only on somewhat higher horizons, such as Spherexochus 
mirus and Lichas laxatus, but the former is recorded by Salter ° 
from Carrickadaggan (County Wexford) with the same Cystideans. 


The occurrence of this Lower Ordovician fauna with apparently 
Kast European affinities in the western part of the British Isles is of 
great interest with reference to the questions of ancient bio-geo- 


1 Marr & Roberts, Quart. Journ. Geol. Soc. vol. xli (1885) p. 476. 

? Schmidt, Quart. Journ. Geol. Soc. vol. xxxviii (1882) p. 521, & ‘Rev. 
Ostbalt. Silur. Trilob.’ pt. i (1881) p. 23. 

° Nathorst, Sver. Geol. Undersokn. Ser. Ba, No. 4 (1884); Moberg, ibid. 
Ser. C, No. 109 (1890) p. 18; Tullberg, ibid. Ser. C, No. 50 (1882); Frech, 
* Leth. Geogn.’ pt. i, vol. ii (1897) pp. 72-77. 

4 Quart. Journ. Geol. Soc. vol. xxxviii (1882) p. 313. 

5 Tullberg, op. cit. pp. 19 & 20. 

® Monogr. Palzont. Soc. ‘ Brit. Trilob.’ 1864, p. 79. 


770 MR. F.R,C. REED ON THE LOWER PALZOZOIC [Noy. 1899, | 


graphical provinces and the extension and distribution of the seas 
and lands of this period. On the strength of the evidence afforded by 
the trilobites, Frech' distinguished four marine provinces in Lower 
and Middle Ordovician times; the British Isles lay in the North 
Atlantic province, and Scandinavia and Russia in the Baltic province. 
But of the twenty genera of trilobites which he quotes as peculiar 
to the latter province, five have long been known from the British 
Isles, another is not peculiar to the province, another is very rare 
and found only in Russia, seven others belong to beds lower than 
any that we are comparing, and another to a much higher horizon. 
Marr” believed that the large Asaphi of the Orthoceras-limestone 
of Sweden did not reach Britain till Lower Bala times, and the 
Cystideans and Phacopes of the subgenus Chasmops not till the 
Middle Bala was being deposited. 

It seems, however, that the connexion between the Baltic and 
Irish areas was closer and somewhat earlier, though in what manner 
this happened is obscure. The differences in the Baltic and Irish 
faunas appear to be only such as the distance and probable diversity 
of local conditions and sedimentation would lead us to expect. A 
suggestion of the propinquity of the British contemporary facies is 
afforded by the occurrence of certain typical British species (Caly- 
mene duplicata, Bellerophon perturbatus, etc.) in the higher beds, 
which shows the gradual loss of Baltic characters and the influx of 
British forms. The immigration into England of the Cystideans 
and of the forerunners of the Middle Bala Chasmopes may, therefore, 
have come as much from Ireland as from their headquarters in the 
Baltic area. 

We may conclude that during the accumulation of the greater 
part of the Tramore Limestones the physical and biological conditions 
in Wales and England did not allow of the spread of their peculiar 
fauna. But from the time of the deposition of the Dicranograptus- 
shales the conditions continuously approximated. 

Volcanic activity in County Waterford is seen to have commenced 
about the period of the accumulation of the Dicranograptus-shales 
near Tramore, and possibly earlier at Raheen, where also it con- 
tinued till after the Orthis argentea-beds had been deposited. In 
the Haverfordwest area volcanic rocks of this age have not been 
described, but farther west and north in the St. David’s and 
Fishguard districts Dr. Hicks* and the present writer* have recorded 
felsitic lavas and tuffs of Lower, Middle, and Upper Llandeilo age. 


VII. Concivston. 


The facts above recorded show that the bedded Ordovician rocks 
of the Waterford coast represent mainly the Llandeilo (Lower Bala) 
of England and Wales, but are of special interest because they 


1 «Leth. Geogn.’ pt. i, vol. ii (1897) pp. 88 & 89. 

2 Quart. Journ. Geol. Soc. vol. xxxviii (1882) p. 313. 
3 Ibid. vol. xxxi (1875) p. 167. 

4 Ibid. vol. li (1895) p. 149. 


q 


HIN 


Edwin Wilson, Cambridge. 


TRILOBITES FROM THE 
WATERY ORD COAST 


Vol. 55. ] . BEDDED ROCKS OF COUNTY WATERFORD. 771 


possess a heteropic type of development and:a faunistic facies allied 
to that of Eastern Europe. Volcanic activity accompanied their 
deposition. 

No Middle or Upper Bala sedimentary beds have been recognized, 
but it is probable that Arenig beds are present, though as yet 
paleontological evidence is wanting. 


I wish especially to express my thanks to Sir A. Geikie for 
permission to examine the Survey Collections in Dublin, and my 
indebtedness to Mr. McHenry, of the Irish Geological Survey, for 
much yaluable help and attention. 


EXPLANATION OF PLATE XLIX. 


Trilobites from the Waterford Coast. 


Fig.1. Remopleurides Salteri, sp. nov. A slightly compressed head-shield 
without free cheeks. x 4. In the Dublin Museum. 
2. Do. Thorax. x 4. In the Dublin Museum. 
3. Do. Head-shield shortened by compression. Xx 4. In the Dublin 
Museum. 
4, Remopleurides Portlocki, sp. nov. Head-shield without free cheeks. 
x 3. In the Dublin Museum. 
5. Remopleurides tuberculatus, sp. nov. A slightly distorted glabella. 
x 2. In the Woodwardian Museum. 
6. Cybele tramorensis (Reed). Imperfect head-shield. x 2. In the 
Dublin Museum. 
7. Cybele McHenryi, sp. nov. Imperfect head-shield. x 4. In the 
Dublin Museum. 
8. Cybele sex-tuberculata, sp.nov. Imperfect head-shield. x 4. In the 
Dublin Museum. 
9. Encrinurus fallax, sp. nov. Imperfect head-shield. x 4. In the 
Dublin Museum. 
10. Do. Free cheek. Xx 6. In the Woodwardian Museum. 
11. Do. Pygidium. xX 4. Inthe Dublin Museum. 
12. Do. Complete young individual. x 4. In the Dublin Museum. 
13. Asaphus Haughtoni, sp. nov. Perfect pygidium. Nat. size. In the 
Dublin Museum. 
14. Tramoria punctata, gen. et sp. nov. Portion of head-shield. x 2. 
In the Dublin Museum. 
15. Do. Cast of portion of head-shield. x 2. In the Dublin Museum. 
16. Do. Imperfect free cheek. x2. In the Dublin Museum. 


Discussion. 


Prof. Sottas, from a personal knowledge of the district, could 
bear testimony to the faithful descriptions of the Author, and com- 
plimented him on a very complete piece of work. The suggested 
comparison of the Tramore Limestones with the Orthocerenkalk of 
the Baltic was of extreme interest, for hitherto the distinction 
between the British and Baltic provinces during Lower and Middle 
Ordovician times had been regarded as so sharp’ that authors had 
invented a special isthmus to account for their separation. No 
doubt the paleontological evidence, when presented in detail, would 
support the Author in his contention ; but, for the present, it might 
be noted that Amphion, though a rare genus, had always been 


772 LOWER PALHOZOIC ROCKS OF COUNTY WATERFORD. [Nov. 1899. 


regarded as widely distributed and not peculiar to the Baltic, while 
of the 20 genera and subgenera of trilobites which were recognized 
as peculiar to the Baltic region, few, if any, were mentioned by the 
Author as occurring in the Waterford district. 

Prof. Warts also spoke. 

The AurHor expressed his gratification at the manner in which 
his paper had been received, and, in reply to Prof. Sollas, said 
that the fauna of the Tramore Limestone Series had decidedly not 
the same facies as that of the Llandeilo Limestone, which was an 
approximate equivalent in Wales. He had therefore looked else- 
where for a similar facies, and had been struck by the resemblance 
borne by the beds immediately below the Dicranograptus-shales in 
the Baltic area. The evidence was set forth in detail in his 


paper. 


GENERAL INDEX. 


TO 


THE QUARTERLY JOURNAL 


AND 


PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 


Acanthosphera australis, sp. nov., 48 
& pl. viii. 

Etheridgei, sp. nov.,49 & pl. viii. 

Accentor modularis (?) fr. Ightham 
fissure, 420. 

‘Achliz Urika (S. Morocco), sect. to 
Jebel Asif Sig, 204. 

Actinolite-prisms in Beinn Donachain 
limest., 484; act. rocksin Anglesey, 
292; act.-tufts in rocks nr. junc- 
tions ibid., 294-297 & pl. xxili 
(microse. sects.). 

A£olian, see Wind-action. 

Agglomerate of Cleary’s Hill(N.S.W.), 
23, 35-36; agel. & tuffs in Carb. 
Limest. Series of Congleton Edge, 
548-559 w. map & sects.; agglom. 
in Ordoy. of Waterford coast, 723 
et seqq. 

Aghnagreggan (Tyrone), granite & 
sandst.-junction, 274, 275 fig. 

Alders Farm cutting (Derby), 225. 

Alleghe, Lake (S. Tyrol), area of con- 
verging faults, 624. 

Ambulacrum, single, vars. of, in 
Micraster, 502-503. 

Amia anglica, sp. nov., 3, 5 & pl. i. 

Colenutti, sp. nov., 8 & pl. i. 

——,, distrib. of recorded spp., 9. 

Ammonites armatus-beds, betw. Rugby 
& Catesby, 71. 

capricornus-beds ibid., '79. 

Henleyi-beds ibid., '78. 

ibex-beds 2bid., 77. 

—— Jamesoni-beds ibid., 77. 

—_ obtusus-beds ibid., 68. 


Ammonites oxynotus-beds, betw. Rugby 
& Catesby, 69. 

pettos-beds ibid., 75. 

raricostatus-beds ibid., 71. 

semicostatus-beds ibid., 67. 

—— Turneri-beds ibid., 67. 

Ampysx cf. Volborthi, 745. 

Amselfluh-Wiesen fold (Davos), 401 & 
pl. xxvii (sect.). 

Amsmiz, Wad (Atlas Mts.), geol. of, 
207 w. sect. 

Ancylus Vinti, see Carbonicola. 

AnpErson, Gr., quoted, 413. 

Anpzrson, T., quoted, Ixxxvi. 

Andesite-tuff of Waihi, 463-464. 

Andesitic basalts of Raggedstone Hill, 
ete., 138, 141 ; gold-bearing do., of 
Hauraki, 449, 464-465 & pl. xxxiii 
(microse. sect.) 

Anprews, O. W., quoted, 89. 

Anglesey, serpent. & assoc. rocks in, 
276-304 figs. & pl. xxiii (microse 
sects.) ; (N.), geol. of, 635-680 figs. 

Annestown (Waterford), Lr, Palzoz. 
of, 735-736 fig. 

Annual General Meeting, ix. 

Anser sp., fr. Ightham fissure, 419. 

Ansty Lane (Cuckfield), Wealden 
bird (?) from, 416-418 figs. 

Anthracomya calcifera, sp. noy., 865— 
366 & pl. xxv. 

Anti-Atlas, sect. to Tezert, 200. 

Apatite, interlam. w. magnetite at 
Gellivaara, i. 

Aplite of Sorel Point, 430 e¢ segq. 
specific gravity of same, 444. 


774 


Archean pebbles in Middle Perm. 
conglom., 118-119 & table iii ; Arch. 
rocks of 8. Malverns, 131 e segq.; 
junct. w. Llandovery strata in 
Hollybush Pass, 143 fig.; Arch. 
moraine-material of Nordenskjold 
- Glacier, 684 & pl. xlviii. 

Ardrishaig Series, 473, 475-476 et 
seqq.; progressive metamorphism in, 
480-482, 

Argiline-beds of Trinidad, orig. of, 

187. 

Arlberg-kalk of Davos district, 387. 

Arnoup-Bemrossz, H. H., on Geol. of 
Ashbourne & Buxton Ry.: Ash- 
bourne to Crake Low, 224-237 figs. 
& pls. xvii-xviii (sects.); on a Sill 
& Faulted Inlier in Tideswell Dale 
(Derby), 239-249 figs. & pls. xix—xx 
(map & microse. sects.); on Petrogr. 
of Rocks of Congleton Edge, 556- 
559; quoted, 716. 

Arosa-Cotschna fold (Davos), 405- 
410 figs. & pl. xxvii (sect.). 

Asaphus Haughtoni, sp. nov., 757-758 


& pl. xlix. 
—— (Ptychopyge?) radiatus, 756- 
757 


Lae, ) sp., 757. 

Ash, peace in Carb. rocks betw. 
Ashbourne & Crake Low, 225 e¢ 
seqq., 233-234; ejected blocks in 
same, 234-235; in Ordov. of Water- 
ford coast, 721 et seqg. ; see also Tuff. 

Ashbourne & Buxton Ry., geol. of, 
224-238 figs. & pls. xvii-xviii (sects. ). 

Ashes Farm cutting (Derby), 225. 

Asif el Mel (Atlas Mts.), geol. of, 210- 
211 w. sect. 

Asif Sig, Jebel (Atlas Mts.), sect. to 
Achliz Urika, 204. 

Asta-Judicarian region, applic. of 
principles of torsion to, 625-632 w 


map. 

Aebary Limeworks (Cheshire), sects. 
at & near, descr. & fig., 550-552. 

Asteroidea contrasted w. Echinoidea, 

° 9706-707, 710-714. 

“Astley Bank (Shropshire), Perm. at, 
T9110. 

ArvuErstone, W. G., obituary of, lviii. 

Atlas Mts. & S. Morocco, geol. of, 
190-212 w. sects. 

Attermire Scar (Yorks), fault-escarp- 
ment, pl. xxiv facg. 339. 

‘Arrwoon, M., obituary of, lix. 

Auditors elected, v. 

Augite-andesite, altered, of Waite- 
kauri, 465. 

Augite-porphyrite of S. Tyrol, 585. 

Auriferous, see Gcld-bearing. 


GENERAL INDEX. 


[Nov. 1899, 


‘ Austonungszone’ 
156. 

nee in crush-conglomerates, 

Avalonia, generic value discussed, 93 
et seqq. 

Avicula contorta-shales of Davos dis- 
trict, 386, 400; see also Rheetic. 

Awaruite (?) in Anglesey serpentine, 


in Malvern area, 


Awe, Loch (Argyll), progressive meta- 
morphism i in Dalradian of region, 
470-493 w. map. 

nae (S. Morocco), Tertiaries of, 
1 


Baggeridge-Sedgley area (Staffs), 

ue & Upper Perm. of, 114, 
15 

Bala age of Green Series in N. Angle- 
sey denied, 643 ; (Lr.) age of strata 
of Waterford coast, 770-771. 

Balance-sheet for 1898, XXX1V—XXXvV. 

Ballydouane Bay (Waterford), Lr. 
Palzoz. of, 738-739. 

Ballyvoyle (Waterford), Lr. Palzoz. 
betw. Killelton Cove and, 739-740. 

Banded serpentine in Anglesey, 281. 

Barbados (W.I.), Gdlobigerina- & 
radiolarian beds comp. with those 
of Trinidad, 184-187 w. vert. sect. 
& chem. anal. 

Barham (Kent), Pecten fr. Chalk Marl 
Oly KC: 

Barwtow-JAMESON Fund, list of reci- 
pients, xxxi. 

Barr (Staffs), Perm. of, 116. 

Barraba (N.S.W.), radiolar. rocks of, 
17, 18 e segq., 38. 

Basalt-tuff of Congleton Hdge, 556. 

Basalts in Malvern area, 138, 141, 
149, 158 et segg.; in Atlas Mts., 
199, 201, 203 e¢ segg.; in Loch Awe 
region, 479; use of term, 169; see 
also Andesitic, ete. 

Bastite-serpentine in Anglesey, 288 & 
pl. xxiii (microse. sect.). 

Batuer, F. A., on Pyramid-pebbles or 
‘ Dreikanter,’ xc—xci. 

Bavermay, H., on Gellivaara & Kiiru- 
navaara iron-ore deposits,i; elected 
Auditor, v. 

Brasury, H. C., quoted, lxxxix. 

Brrcuer, C. E., elected For. Corr., 
Xcil. 

Bett, D., obituary of, lix. 

Belvedere ridge (S. Tyrol), relat. to 
Col di Lana, 589. 

Bembridge Beds, Amia from, 2, 3, 7. 

Bennikz, J., Murchison Fund Award 
to, xly. 


Vol. 55. | 


Bentley Hall cutting (Derby), 226. 

Bertrand, Marcet, elected For.Memb., 
v. 

Biessy Medallists, list of, xxxi. 

Bingara (N.S.W.), radiolar. rocks of, 
17, 18 et seqq., 38. 

Biotite-gneisses of Davos district, 384. 

Biotite-rhyolite fr. Waihi, 461-462 & 
pl. xxxili (microse. sect.). 

Bird (?) fr. Wealden of Ansty Lane, 
416-418 figs. 

Black Shales (Cambrian) of S. Mal- 
verns, etc., 140 e¢ segg,, 157 et seqg. 

Bled Hummel (Morocco), Lr. Cret. 
red shales & sandst. of, 197. 

Blockhouse (Riigen), sect. descr. & 
fig., 320-321. 

Bobbin of indurated shale fr. Howie- 
toun, lxxxvi. 

Bobbington (Shropshire), Upper Perm. 
near, 105, 108 & table i. 

Bodlondeb (Caernarvon), felsitic lavas 
& tuffs of, 170-176 w. map & sect. 
Boe summit (S. Tyrol), stratigr. & 

tectonics of, 605-608 figs. 

Bonney, T. G. (& Miss C. A. Ratsry), 
on Serpent. & Assoc. Rocks in 
Anglesey, 276-302 figs. & pl. xxiii 
(microse. sects.) ; (& Rev. E. Hit), 
on Relats. of Chalk & Drift in 
Moen & Rigen, 305-324 figs. ; 
quoted, 175, 394, 397, 398, 447. 

Bosworru, J. A., obituary of, lx. 

Boulder-beds of Misfiwa (S. Morocco), 
205; of Scottish Highlands, 487- 
489. 

Boulder Clay betw. Rugby & Catesby, 
79-81, 82; betw. Ashbourne & 
Buxton, 225, 226, 237, 238; in 
Moen & Rigen, 305-326 figs. 

Bova Alp (S. Tyrol), torsion of Pordoi 
overthrust at, 599. 

Bowdon (Cheshire), pyramid-pebble 
found near, xe. 

Bowhills district (Shropshire), Upper 
& Middle Perm. of, 108-110 & 
pl. xi (map). 

Branching spherulites in Hauraki 
rhyolites, 452, 455, 456, 466 & 

Spl. xan. 

Brander, Pass of (Loch Awe), phyllites, 
etc. of, 480, 483. 

Breccias, Perm., of Lr. Severn Basin, 
102, 103 e¢ segg.; Malvern breccias, 
151, 164; breccias in Carb. Limest. 
of Craven district, 333 et seqq. figs., 
343-349 figs.; breccias of Davos 
district, 395-397 fig. 

Breccia-sandstone, Upper Perm., of 
S.E. Shropshire, 105, 111. 

Briart, A., obituary of, lviii. 


GENERAL INDEX. 


775 


Bridgend (Glamorgan), Zanclodon 
cambrensis from, 89-96 & pl. x. 

Brine-springsin Lr. Cret.ofS. Morocco, 
197, 201. 

Broadfield Farm (Enville), Perm. near, 
table i, facg. 108. 

Bronsil (Malverns), geol. struct. of 
district around, 164-166. 

‘Buchenstein agglomerate,’ a shear- 
and-contact breccia, 567-569. 

Buchenstein Valley (S. Tyrol) anti- 
cline, 583-590 w. maps & sects. ; 
its relat. to Sett Sass syncline, 617. 

Buckles, torsion-, 610-611. 

Bucxmay, 8.8., on Gravel at Moreton- 
in-the-Marsh (abs.), 220. 

eee (Staffs), Perm. near, 113, 

15. 


Bindner Schiefer of Davos district, 
385. 

Bunter Beds at Ashbourne, 224, 225, 

Burial-grounds, best sites for, Ixxv. 

Buxton & Ashbourne Ry., geol. of, 
224-238 figs. & pls. xvii-xviii (sects.). 


Cahirconlish (Limerick), Carb. Limest. 
vole. rocks of, 237, 288. 

Se ee of Beinn Donachain, 

Calc-hornfels, limest. altered into, 483. 

Calcareous tufa in 8. Morocco, 195, 
196. 

Calymene brevicapitata, 750. 

Cambrian pebbles in Middle Perm. 
conglom., 119; Black & Grey Shales 
of S. Malverns, ete., 140 e seqq., 
157 et segq. 

Campolungo Pass (S. Tyrol) anticline, 
H. flexure-fault of, 613-615; 
continuation of, 616. 

Canis lupus (?) fr. Ightham fissure, 
427-428. 

Carbonicola Vinti, 367-368 & pl. xxv. 

Carboniferous foss. found in Middle 
Perm. conglom., list of, 125; sand- 
stone-pebbles in same, 122 & table 
iil; Carb. lamellibr., three new spp., 
365-371 & pl.xxv; Carb. rocks N. & 
S. of Craven Fault, 328, 349-351 ; 
Carb. nunatak on Nordenskjold 
Glacier, 684. 

Carboniferous Limestone pebbles in 
Middle Perm. conglom., 122, 123 & 
tables iii-iv; OC. L. betw. Ashbourne 
& Crake Low, 224 et segg.; O. L. 
altered by igneous rocksin Tideswell 
Dale, 239 et segg. ; OC. L. of Derby- 
shire, sponge-spicules in, 716-717. 

Carp, G. W., quoted, 20, 31, 37. 

Cardium (?), Mioc., fr. Ormara, vi. 


776 


Carposphera nana, sp. nov., 215 & 
pl. xvi. 

Carrigaghalia (Waterford), cliff-sect. 
descr. & fig., 730. 

Carrigaghalia Series, 740-741, 742; 
correl. w. Dicranograptus-shales of 
S. Wales, 767. 

Casanna Schiefer of Davos district, 
390, 391, 401, 411, 412. 

Cassian strata in 8. Tyrol, 561 e 


seqq. 

Giselle (S. Tyrol) & Pralongia thrust- 
plane, 619-620. 

Castle Hill (Shropshire), Upper Perm. 
ola lle 

Catesby (Northants), sects. betw. 
Rugby and, descr. & fig., 65-88 w. 
list of foss. 

Cemaes (Anglesey), broken-up beds 
near, 657, 658 fig.; crush-breccias 
of, 660 fig., 661-665 figs. 

Cemeteries, best sites for, lxxv. 

Cenellipsis favosa, sp. nov., 216 & 
pl. xvi. 

— scitula, sp. nov., 216 & pl. xvi. 

setosa, sp. nov., 216 & pl. xvi. 

Cenospheraaffinis, sp. nov., 44 & pl. viil. 

scitula, sp. nov., 43 & pl. viii. 

Cerig-moelion (Anglesey), variolit. 
serpentine near, 283, 284, 288, 
ophicalcite of, 289; porphyrite (?) 
of, 294; actinolitic rock of, 296. 

Chalk, relats. w. Drift in Moen & 
Rigen, 305-326 figs. ; anal. of Mz- 
craster from, 494-547 & pls. xxxv— 
Xxxix. 

Chalky Lower Boulder Clay, nr. Rugby, 
81. 

Cuapman, F., Lyell Fund Award to, 
xlvii. 

Chase End Hill (Malverns), geol. 
struct. of, 148-149 fig., 155. 

Chawnhill (Staffs), Perm. near, 112, 
118, 114. 

Cheirurus gelasinosus, 748-749. 

Chepstow (Monmouth), foss. oak from, 


iv. 

Cherts, radiolar., of N.S.W., 20 ez 
segg., 88; do. of Mullion Parish 
(Cornw.), 214; ch. in limest. betw. 
Ashbourne & Crake Low, 226 e¢ 
seqgg., 286; in Draughton Quarry, 
3309 fig. 

Cherz Hill (S. Tyrol) overthrusts, 584 ; 
oblique faultg. across same, 585; 
cliff-exposure in S. face of, 584 fig. ; 
sect. to Buchenstein Valley, 586. 

Chidley’s Farm (Shropshire), Middle 
Perm. near, 103 & table i. 

Chilton (Bucks), glaucon. limest. fr. 
Kim. Clay of, Ixxxvii. 


GENERAL INDEX. 


[Nov. 1899, 


Chlerite-rock in Anglesey, 297-300. 

Chlorite-schists of Loch Awe region,. 
476-478. 

Chonetes papilionacea, occurr. at 
Congleton Edge, 550, 559. 

Chrysotile (?)-veins in Tideswell Dale, 
247. 


Chydenius, Mount (Spitsbergen), 682. 

Chypons Farm (Mullion Parish),. 
radiolar. in chert from, 214-219 & 
pl. xvi. 

Cipit Limestone, 562, 591. 

Claystones, radiolar., of N.S.W., 18,. 
20 et segq., 41. 

Cleary’s Hill (N.S.W.), agglomerate 
of, 23, 35-36. 

Cleavage-phenomena in Groden Pass, 
575; of Sella massive, 604; in N. 
Anglesey, 654-655. 

Clent Hills district (Staffs), Perm. of, 
111-112. 

Cuouey, C. T., & Pounarp, W., on 
Spinel & Forsterite fr. Glenelg 
Limest., 372-379 w. chem. anal. 

Coal Hill (Malverns), geol. struct. of 
district, 157-160. 

Coal Measures (Upper) of N. Staffs, 
Anthracomya calcifera, sp. nov. 
from, 365-366 & pl. xxv; Cardoni- 
cola Vinti fr. same, 367-368 & 
pl. xxv. 

Coal-seam, crushed, in Dale Beck 
Quarry, 351-352. 

Coastal lowlands of S. Morocco, 194— 
196. 

Cockpurn, Gen. C. F., quoted, 519,. 
544. 

Col di Lana (S. Tyrol), relat. to Bel- 
vedere ridge, 589. 

Coxcuester, W., obituary of, lx. 

Coxz,G. A. J., on Age of cert. Granites: 
in Tyrone & Londonderry, 273-275 
fi 


g. 

Cotenutt, G. W., quoted, 2. 

Colfosco (S. Tyrol), portion of Groden 
Pass anticline, 5738. 

Columnar clay in Tideswell Dale, 239 
et seqg., 247-248. 

Compton (Shropshire), Middle & 
Upper Perm., 103, 104, 105; sect.. 
to Gatacre, 106-107. 

Congleton Edge (Cheshire), Agglom. 
& Tufts in Carb. Limest. Series of,. 
548-559 w. map & sects. 

Conglomerate striated by earth- 
movemt., at Melmerby, 11-15 fig. ; 
conglom.inradiolar.series of N.S. W.,. 
23 ; conglom. (Perm.) of Lr. Severn 
Basin, 97-128 w. tables i-ui & 
pls. xi-xii (maps) ; see also Crush- 
conglomerates. 


Vol. 55.] 


OContact-and-shear breccia of Buchen- 
stein, etc., 567-569, 577, 584. 

Contorted Boulder Clay, nr. Rugby, 
80-81; Drifts in Moen & Rigen, 
305-326 figs. 

Conversazione announced, ii. 

Conway, Sir M., quoted, 681. 
Conway (Caernarvon), felsitic lavas & 
tuffs near, 170-176 w. map & sect. 
Corals in Devonian limest. of Tam- 

worth (N.S.W..), list of, 28-29. 

Coral-limestone in radiolar. series of 
N.S.W., 25, 61; in Carb. Series of 
Tideswell Dale, 239, 240, 248. 

Oorner, F., quoted, 419. 

Corrie Glacier (Spitsbergen), 689 & 
pl. xliv. 

Cortina area (S. Tyrol), tectonics of, 
624. 

Corvara-Pescosta Fault (S. Tyrol), 
573-574. 

Coscinium cf. proavum, 762. 

Coton Hall (Shropshire), Perm. near, 
110. 

Cotschna-Arosa fold (Davos), 405- 
410 figs. & pl. xxvii (sect.). 

Council Report, ix. 

Council & Officers elected, xxiv. 

Cra di Mont (S. Tyrol), 599, 601. 

Cracoe (Yorks), limest.-knolls near, 
338. 

Craig Wen (N. Anglesey), Ordov. 
foss. found near, 640; sect. in quarry 
on E. side of, 671. 

Crake Low cutting (Derby), 229-231 
fig. & pls. xvii—xviii (sects.); C. L. 
Quarry, 231 & pl. xvili (sect.). 

Craven district (Yorks), limest.-knolls 
in, 327-364 figs. & pl. xxiv; Craven 
Faults, 328; nat. of disturb. S. of 
same, 331-388, 351-354; Carb. 
rocks N. & S. of same, 328, 349- 
351. 

Cretaceous rocks of 8S. Morocco, 197- 
198, 199 e¢ segg. 

Cromer (Norfolk), ammonite from, 
xci; comparison of Drifts w. those 
of Moen & Rigen, 321, 325, 326. 

‘ Cross-arches’ of Sett Sass, etce., 
621. 

Cruach Mhor (Loch Awe), boulder- 
bed of, 488. 

Cruachan (Ben) granite, its infil. on 
metamorph. of neighb. area, 485, 
489, 491. 

Cruglas (Anglesey), serpentine of, 284, 
285. 


Crush-breccias & crush-conglomerates 
in N. Anglesey, 657-667 figs., 677- 
678; seealso Fault-breccias, Contact- 
and-shear breccias, ec. 


Q. J.G.8. No. 220. 


GENERAL INDEX. 


7717 


Crushing, as a result of earth-movemt. 
in N. Anglesey, 655. 

Crystallines, older, of Davos district, 
384-385. 

Ctenodonta pentonensis, sp. nov., 368- 
370 & pl. xxv. 

Ouckfield (Sussex), Wealden bird (?) 
fr. Ansty Lane, 416-418 figs. 

Cybele McHenryi, sp. nov., 751-752 & 
pl. xlix. 

sex-tuberculata, sp. nov., 752- 

753 & pl. xlix. 

tramorensis, 750-751 & pl. xlix. 

Cyrtoidea absent fr. radiolar. cherts 
of Cornwall, 219. 

Cystocidaroida, proposed amendment 
of diagnosis, 701. 


Dachstein Dolomite, rock-success. 
below the, 561-562; exposures of, 
600, 605, 606. 

Daxyns, J. R., on Limest. Knolls 
below Skipton & Grassington in 
Craven, 359-361. 

Dale Beck Quarry (Yorks), breccias 
in, 844-345; crushed coal-seam in, 
351-352. 

Dalradian of Loch Awe region, pro- 
gress. metamorph. in, 470-493 w. 
map. 

Dalton-in- Furness (Lanes), knoll- 
struct. in Coniston Limest. near, 355, 
356. 

Danes, W. B., obituary of, liii. 

DarsBisuireE, R. D., quoted, xe. 

Davin, J., quoted, 89. 

Davin, T. W. EH. (& Prrruan, E. F.), 
on Paleoz. Radiolar. Rocks of 
N.S.W., 16-37 fig. w. anal. & pls. ii- 
vii (map & sects,); Bigsby Medal 
awarded to, l. 

Davies, A. M., on Glaucon. Limest. 
fr. Kim. Clay, lxxxvii. 

Davos district (Switzerland), geol. of, 
381-412 figs. & pls. xxvi-xxvii (map 
& sect.). 

Detcano, J. F.N., elected For. Memb., 
xcii. 

Demnat, Wad (Atlas Mts.), geol. of, 
199-201 w. sect. 

Denudation above snow-line in Spits- 
bergen, 688-689 & pl. xlviii. 

Derbyshire, sponge-spicules in Carb, 
Limest. of, 716-717 ; see also Ash- 
bourne, Tideswell Dale, etc. 

Devonian age of radiolar. rocks of 
Tamworth & Jenolan (N.S.W.), 
30-31 ; radiolar. in same, 38-63 & 
pls. vili-ix; D. limest. of S. Devon, 
knoll-struct. in, 857; D. rocks in 
Spitsbergen, 683, 688, 689. 

3 


778 


Diabases, in Malvern area, 158, 161, 
163, 164; intrus. of granite into, 
at Sorel Point, 430-448 figs. & 
pls. xxix—xxx (microse. sects.) ; diab. 
of Davos district, 397-398 ; boul- 
ders in Spitsbergen, 689; diab. on 
Waterford coast, 727, 730, 736 ; use 
of term, 169. 

Diagonal faults of H. side of Groden 
Pass, 573-574; of Pralongia-Sora- 
ruaz, 585, 615; Stuores bundle of, 
615-616 ; diag. dispos. of Dolomite- 
massives w. respect to Groden Pass 
anticline, 575-576 ; charact. furcat. 
of diag. faults, 581-582. 

Diallage-rocks in Anglesey, 279, 290. 

Diatom-frustules, formg. iridescent 
scales in radiolar. earths of Trinidad 
& Barbados, 186-187. 

Diszey, G. E., exhib. specims., xe. 

Dicranograptus-beds of Penterfyn, 640, 
672. 

Diganwy (Caernarvon), nodular fel- 
sites at, 175. 

Dinas-bach (Anglesey), 
gabbro of, 293. 

Diopside (white augite) of Glenelg, 
376, 377. 

Diorite in Atlas Mts., 205, 207, 210. 

Distriactis vetusta, sp. nov., 53 & pl.ix. 

Divining-rod, & the search for water, 
lxxi-]xxii. 

Dodd’s Barn (Shropshire), Perm. at, 
108, 109. 

Dolerite in Tideswell Dale, 240 et segq., 
245-247 & pl. xx (microse. sects.) ; 
in Holyhead I., 294; in Loch Awe 
region, 479; of Dunabrattin, etc., 
736, 739. 

Dolomites, torsion -struct. in, 560- 
634 figs. & pl. xl (map); Carb. 
dolom. in Spitsbergen, 688 ; Permo- 
Carb. zbid., 689. 

Dolomitic Wenlock Limestone-pebbles 
in Middle Perm. conglom., 120-121 
& tables iii-iv; dolomitic veins in 
Anglesey serpentine, 277. 

Dolomitization influenced by torsion- 
strains, 609; dolomit. of Llan- 
badrig limestone, 669. 

Dolomitized limest. in Carb. rocks 
betw. Ashbourne & Crake Low, 227, 
236; breccia in Draughton Quarry, 
334; limest. of Cracoe & Settle, 
341. 

DonatD, Miss J., on LEctomaria & 
Hormotoma, w. Descr. of Brit. Spp., 
251-272 & pls. xxi-xxii. 

Doneraile Cove (Waterford), cliff- 
sect. betw. Tramore and, 726; cliff- 
sect. N. of, 729. 


enstatite- 


GENERAL INDEX. 


[Nov. 1899, 


Doneraile Walk (Waterford), sects. 
descr. & fig., 727, 728. 

Dorfliberg anticline (Davos), 406. 

Dorysphera echinata, sp. nov., 45 & 
pl. viii. 

Downham (Lancs), limest.-knolls of, 
338, 339. 

Downton Sandstone-pebble in Perm, 
conglom., 121 & table iii. 

Drainage, new system in conn. w. Geol. 
Soc. Apartments, x; dr. of ice- 
sheets in Spitsbergen, 685-686 & 
pl. xlvii. 

Draughton Quarry (Yorks), sect. 
descr. & fig., 331-337 ; breccias of, 
344 fig. 

‘ Dreikanter’ or pyramid-pebbles, xc— 
XCi. 

Drift, to be avoided in reservoir-sites, 
lxix ; Drifts of 8S. & E. Engl., schorl- 
rock pebbles in, 220-223 ; Dr. betw. 
Ashbourne & Crake Low, 225, 226, 
237, 238; relats. w. Chalk in Moen 
& Rigen, 305-326 figs. 

Drift-maps, necessity for, xxix; MS., 
of E. Counties, pres. by F. W. 
Harmer, v. 

Druppalonche clavigera, gen. et sp. 
nov., 217 & pl. xvi. 

ovata, sp. nov., 218 & pl. xvi. 

Ducan fold (Davos), 400 & pl. xxvii 
(sect.). 

Duy, W. S., quoted, 19, 37. 
Dunabrattin (Waterford), Lr. Palzoz. 
of, 736-737 w. sect. & lists of foss. 

Dunoon Phyllite Series, 471. 

Duron-Tiers torsion-system (S. Tyrol), 
626-627. 

Diirrenstein Mountain (8. Tyrol), tec- 
tonics of, 624-625. 

Dyke-and-sill phenomena of Groden 
Pass, 577 ; dykes in crush-zones of 
N. Anglesey, 666; see also Basalt, 
Dolerites, etc. 


Earth-movements, producing striz in 
conglom., 11-15, 128; producing 
knoll-struct., 337, 339 et segg., 357 ; 
producg. breccias, 343; e.-m. & their 
effects in N. Anglesey, 650-667, 
677-678 ; see also Torsion-struc- 
ture. 

Eastern Counties, Drift-maps pres. by 
F. W. Harmer, v. 

Lchinocystis, Protocidaris possibly re- 
ferable to, 710. 

pomum, 707-709 figs. 

Echinodermata, modified classif. of, 
715. 


Vol. 55.] 


Echinoidea, Silur., in Oxf. Univ. Mus., 
692-715 figs. ; evolut. of, 710, 714— 
715; contrasted w. Asteroidea, 706- 
707, 710-714. 

Ectomaria, generic characters, etc. of, 
252-254, 

— (?) exigua, sp. nov., 256 & 
pl. xxi. 

girvanensis, sp. nov., 256 & 
pl. xxi. 

— pagoda var. orientalis nov., 255 
& pl. xxi; var. Peachii nov., 254 & 
pl. xxi- 

Hisenofen-Valparola fault (S. Tyrol), 
621. 

Elbolton (Yorks), limest.-knoll of, 
359-360. 


Ellipsidium castanea, sp. noyv., 51 & 
pl. ix. 

Ellipsoid of torsion, 581. 

Ellipsostigma australe, gen. & sp. nov., 
51 & pl. ix. 

Encrinurus fallax, sp. nov., 7538-755 & 
pl. xlix. 

Englacial material in Spitsbergen, 
effect of nunatakkr on, 684 & 
pl. xlvi; englac. streams ibzd., 685- 
686 & pl. xlvii. 

England (8. & H.), schorl-rock pebbles 
fr. S.W. England in Drift of, 220- 
223. 

Enneberg (S. Tyrol), torsion-struct. 
in, 560-634 figs. & pl. xl (map). 

Enstatite- gabbro in Anglesey, 279, 
293 ; in Davos district, 398. 

Enstatite-rock in Anglesey, 279, 291- 
292. 

Enville (Shropshire), Middle & Upper 
Perm. of, 102-108 w. sect. & 
table i. 

Eocene in S. Morocco, 194. 

Epidiorites of Loch Awe region, 476- 
478; altered, ibid., 486-487. 

Epidosite, limest. altered into, 478. 

Eruptivity, torsional, in Alpine areas, 
628. 

Estimates for 1899, xxxii—xxxiil. 

Eruerines, R., Jun., list of corals in 
radiolar. series of Tamworth 
(N.S.W.), 28-29. 

Ethmodiscus not a deep-water indi- 
cator, 189. 

Eucladia Johnsoni, anatomy of, 692- 
693. 


— Woodwardi, sp. nov., 694-696 - 


figs. 

Bucladide placed in new order, 692. 

Europe, Internat. Geol. Map pre- 
sented, vil. 

Euthemon igerna, gen. & sp. nov., 696- 
699 figs. 


GENERAL INDEX, 


779 


Fahrnitzer Ufer (Rigen), Drift & 
Chalk of, 319-320. 

Falco peregrinus fr. Ightham fissure, 
420. 

Fan - structure in the Sella massive, 
608. 

Fassa (S. Tyrol), strike-torsion at, 
627-628. 

Fault-breccias of Crayen district, ete., 
343-349 figs. 

Fault-dykes of Pitzculatsch, 567 ; of 
Vallbach, 569-570. 

Faulting, in Malvern area, 131 et 
segg., 151 et segg.; in Atlas Mts, 
202, 206, 211, 212; in Chalk of 
Moen & Rigen, 305, 306, 323; in 
N. Anglesey, 640 e¢ segg., 652-654 
figs. ; see also Torsion-structure. 

Felis catus fr. Ightham fissure, 428. 

Fellows elected, i-vil, lxxxiv—xcii; 
number of, ix, x, xxi; names read 
out, x¢, xCii. 

Felsites, nodular, of Bodlondeb, 171 ; 
Ordov. nodular, etc. of Waterford 
coast, 763-765 w. chem. anal.; 
intrusive, ibid., 724 et seqq. 

Felsite-porphyry includg. magnetite 
at Kiirunavaara, 1. 

Felsitic lavas & tuffs ur. Conway, 170- 
176 w. map & sect. 

Felspar-glass, 465. 

Frincn, B. T., quoted, vi. 

Filtering effect of sand, lxxvi. 

Financial Report, xxxii-xxxviii, 

Flint-implements, see Implements. 

Floating ice, gravel formed fr. drop- 
pings of, 220. 

Folding, in Malvern area, 151 ef seqq. ; 
in Atlas Mts., 210, 212; in Chalk & 
Drift of Moen & Riigen, 306 ez segq.; 
in Carb. Limest. of Craven district, 
331 et segg. figs. ; in Davos district, 
399-410 figs. & pl. xxvii (sect.); in 
Loch Awe region, 475-476; in N. 
Anglesey, 651-652 fig.; see also 
Torsion-structure. 

Footprint, monotreme (?), fr. Trias of 
Stourton, lxxxix. 

Foraminiferal cherts in Carb. rocks, 
226 ; foram. marls, see Globigerina- 
beds ; foram. limest. of Draughton, 
334. 

Forchhammers Pynt (Méen), sect. 
descr. & fig., 307, 308. 

F pee ers Awe), igneous rocks from, 


Foreign Correspondents elected, v, 
XCil ; number of, x, xxi; list of 
XXVi. 

Foreign Members elected, ii, v, XCli ; 
number of, x, xxi; list of, xxy. 

3E2 


? 


780 GENERAL INDEX. 


Forsterite fr. Glenelg Limest., 372- 
380 w. chem. anal. 


Four Ashes (Shropshire), Middle © 


Perm. of, 104. 

Fow ter, Sir J., obituary of, 1x1. 

Fowlet Farm (Malverns), geol. struct. 
of district, 161-164. 

Fox, Howarp, quoted, 214. 

Fringilla celebs (?) fr. Ightham fis- 
sure, 420. 

Furrowing of Chalk in Moen & Riigen, 
324. 

Fyne, Glen (Argyll), granite of, 478, 
490, 491. 


Gabbros in Anglesey, 276 e¢ segq., 293 ; 
cause of schistose struct. in same, 
300. 

Gadat, Wad (Atlas Mts.), geol. of, 
201-203 w. sect. 

Garsutt, J., quoted, lxxxix. 

Garnetiferous limestone assoc. w. 
radiolar, rocks of N.S.W., 20. 

Garrarus (Waterford), Lr. Paleoz. 
of, 733 fig. 

Garwoop, H. J., Add. Notes on Glac. 
Phenom. of Spitsbergen, 681-690 & 
pls. xli—xlviii (map, etc.). 

Gatacre (Shropshire), Upper Perm. of, 
105 & tablei; sect. to Compton, 
106-107. 

Guixiz, Sir A., on Pseudo-foss. fr. 
Silur. of Tipperary, ii; his edit, of 
Vol. iii of Hutton’s ‘Theory,’ x, 
lxxxix; receives Murchison Fund 
Award for J. Bennie, xlv. 

Gellivaara (Sweden), iron-ore de- 
posits, 1. 

Geological Literature, Record of, xi. 

Geological Survey, Index Map, i, xiv ; 
l-inch Maps pres., ili, vii, Ixxxiv, 
Ixxxix; more detailed maps neces- 
sary, lxxix—lxxxi ; proposed removal 
to S. K., xxx. 

Gizson, W., & Hinp, W., on Agglom. 
& Tuffs in Carb. Limest. Series of 
Oongleton Hdge, 548-555 w. map & 
sects. 

Gilbert’s Cross (Shropshire), Perm. of, 
105 & table i. 

Gillow Heath (Cheshire), sect. on road 
to Congleton deser. & fig., 554- 
550. 

Gindafy (Atlas Mts.), geol. of, 209- 
210 w. sect. 

Glacial deposits betw. Rugby & 
Catesby, 79-82; in Atlas Mts., 199, 
202, 2038 et segg.; glac. phenom, in 
Spitsbergen, 681-691 & pls. xli- 
xlviii (map, etc.) ; glac. strize con- 
trasted w. slickenside-strize, 13, 


[ Nov. 1899, 


Glacier, definition of term, 682. 

Glauconitic limestone fr. Kim. Clay, 
Ixxxvil. 

Glauwa (Atlas Mts.), geol. of, 205. 

Glenelg Limestone (Inverness), spinel 


& forsterite from, 372-380 w. chem. 


anal, 

Globigerina-marls of Trinidad & Bar- 
bados, 181 e¢ segg. w. chem. anal. 

Glyptocystis cf. pennigera, 762. 

sp. (Tramore Limest.), 763. 

Gneisses of Davos district, 384. 

Gold-bearing veins assoc. w. serpentine 
in N.S.W., 18; g.-b. andesites of 
Hauraki, 449. 

Goniocidaris canaliculata, 711, 712 
figs. 

GoopEnoveu, Sir W. H., obituary of, 
Ixi. 

Gorpon, Mrs., see Ocinvin, M. M. 

GouLp, C., obituary of, Lxii. 

Graig-fawr (Anglesey), variolit. ser- 
pentine & gabbro near,. 276, 281, 
283, 286 et seq. 

Granites of Tamworth district (N.S. 
W.), 20; of Tyrone & London- 
derry, age of, 273-275 fig.; of 
Northern Jersey, intrus. into dia- 
base, 430-448 figs. & pls. xxix-xxx 
(microse. sects.) ; tale-gran. of Davos 
district, 398 ; gr. of Ben Cruachan, 
478, 485, 489; of Glen Fyne, 478, 
490, 491. 

Granophyric struct. in Waterford 
felsites, 764, 765. 


‘Graphitic slates in Loch Awe Series, 


474. 

Grassington (Craven), limest.-knolls 
below, 359-361. 

Gravel at Moreton-in-the Marsh, 
220. 

Great Central Railway, geol. of, 65- 
88 figs. w. list of foss. 

Green Series in N. Anglesey, 637-638 ; 
relat. of same to Ordovie. ibzd., 638— 
667 figs. ; pre-Llandeilo age of, 674; 
microsc. char. of, 675-676. 

Greenstones in Anglesey, 294. 

Greocory, J. W., quoted, 681, 692, 
693. 

Grey Shales (Cambrian), of S. Mal- 
verns, etc., 141 e¢ segg., 157 e¢ 
seqq. 

Grits, caleareous, of Congleton Edge, 
558. 

Grit-breccias, 349. 

Grit-knolls, 341. 

Groden Pass (8. Tyrol) anticline, 
566-583 w. maps & sects. 

Groom, T. T., on Geol. Struct. of 
S, Malverns & of Adjac. Distr. to 


==. 


Vol. 55.| 


the west, 129-168 figs. & pls. xiii- 
xv (map, etc.). 
Grimer Fieck (S. Tyrol), peripheral 
overthrust of Sella at, 5938-596. 
Gullet Pass (Malverns), geol. struct. of, 
148. 
GimBeL, CO. W. von, obituary of, liii. 
GwinneELL, W. F., exhib. specims., xc. 


Hadid, Jebel (S. Morocco), iron-ores 
of, 198. 

Hatt, J., obituary of, liv. 

Hamstead (I. of Wight), Amza from, 


2B. TF: 
Handsworth (Staffs), Perm. of, 116, 
118 


Harmer, F. W., pres. MS. Drift Maps 
of E. Counties, v. 

Harpes Flanagani, 745. 

Harrison, J. B., Wollaston Fund 
Award to, xli; on Geol. Success, in 
Naparima District (Trinidad), 181- 
188 w. map, vert. sects. & chem. 
anal, 

Hauptdolomit of Davos district, 386- 
387, 403. 

Hauraki Goldfields (N.Z.), rhyolites 
of, 449-469 w. chem. anal. & 
pls. xxxi-xxxiv (map & microsc. 
sects. ). 

Hayrnr, H., obituary of, Lxii. 

Hekla Hook Beds, 688, 689, 690. 

Helwosestrum nigrum, sp. nov., 54 & 
pl. ix. 

Heliosoma echinatum, sp. nov., 50 & 
pl. ix. 

Parone, sp. nov., 50 & pl. ix. 

Helwsphera clavata, sp. nov., 50 & 
pl. viii. 

—- fenestrata, sp. nov., 49 & pl. viii. 

robusta, sp. nov., 49 & pl. viii. 

Tamworthi, sp. nov., 49 & pl. viii. 

Helkopoda, new group, 714, 715. 

Hemiomus major, gen. & sp. nov., fr. 

- Tonbridge, 413-415 figs. 

High Holborn (London), Palzolith. 
impJemts. from, xcii. 

Highway Close Barn cutting (Derby), 
229, 230 figs. & pls. xvii—xviii 
(sects.), 231 et segq. 

Highway Glacier (Spitsbergen), sur- 
face-stream on, 685 & pl. xlvii. 

Hit, Rev. E., & Bonnzy, T. G., on 
Relats. of Chalk & Drift in Moen & 
Rigen, 305-324 figs. 

Hitt, J. B., on Progress, Metamorph. 
of Dalradian Sedim. in Region of 
Loch Awe, 470-492 w. map. 

Hino, W., on Three New Spp. of 
Lamellibr. fr. Oarb. Rocks of Gr. 


GENERAL INDEX. 


781 


Britain, 365-370 & pl. xxv; & Gis- 
son, W., on Aggiom. & Tuffs in 
Carb. Limest. Series of Congleton 
Kdge, 548-555 w. map. & sects. 

Hinpe, G. J., on Radiolar. in Devon. 
Rocks of N.S.W., 38-63 & pls. viii- 
ix; on specims. of those rocks, 11; 
elected Auditor, y; on Radiolar. in 
Chert fr. Chypons Farm, Mullion 
Parish (Cornw.), 214-219 & pl. xvi; 
quoted, 394-325, 642. 

Hippurites sp. fr. Chalk of Wouldham, 
xe. 

Hirundo rustica fr. Ightham fissure, 
420. 

Holaster planus-zone, 
Micraster in, 512-518. 

Ho.uanp, Pu., chem. anal. of Hauraki 
rhyolites, 467. 

Hollybush Conglomerate & Quart- 
zite, of Midsummer Hill, etc., 139, 
145. 

Hollybush Hill (Malverns), geol. 
struct. of, 188-142 figs. & pl. xiii 


features of 


(map). 

Hollybush Pass (Malverns), geol. 
struct. of, 147-148. 

Hollybush Sandstone, of Raggedstone 
Hill, 133 e¢ segg.; of Midsummer 
Hill, ete., 189 e¢ segg.; of White- 
leaved Oak, etc., 158 ez seggq. 

How, G., elected For. Corr., xcii. 

Holyhead (Anglesey), serpentine, 
gabbro, etc. of, 278-280. 

Horizonal types of Mieraster, 496. 

Hormotoma, generic characters, etc. of, 
257-262. 

——- antiqua, sp. nov., 270 & pl. xxii, 

articulata, 268 & pl. xxii. 

cingulata, 264 & pl, xxi. 

—— (?) dubia, sp. nov., 263 & pl. xxi. 

—— (?) gracillima, 263 & pl. xxi. 

—— Grayiana, sp. nov., 270 & pl. xxii. 

Griffithi, sp. nov., 267 & pl. xxii. 

—— (?) Pipert, sp. nov., 266 & pl. 


Xxii. 

— Salteri, 262 & pl. xxi. 

similis, sp. nov., 268 & pl. xxii. 

Hornblende-andesites of Waitekauri, 
464-465. 

Hornblende-schists of Loch Awe re- 
gion, 476-478; altered, zbid., 486- 
487. 

Horne, Jonny, Murchison Medal 
awarded to, xliii. 

Hornfels of Beinn Buidhe, ete., 490. 

Hornstones, radiolar., of Davos dis- 
trict, 394-395. 

Hornsunds Tinde (Spitsbergen), rock- 
sculptg, above snow-line, 688 & 
pl. xlviii. 


782 


Houseroof structure on Hornsunds 
Tinde, 690. 

Howietoun (Stirling), bobbin of indu- 
rated shale from, Ixxxvi. 

Hurlet Limestone horiz. of Penton 
Linns, Ctenodonia pentonensis, sp. 
nov. from, 368-370 & pl. xxv. 

Hurron’s ‘Theory of the Earth,’ 
vol, iii. of, x—xi, lxxxix. 

Hyalomorphs=vitrified felspars, 462, 

Hyalostelia Smithii, struct. of spicules 
in, 716. 

Hyuanp, J. 8., obituary of, lxii. 

Hyolithes cf. striatus, 762. 


Ice, Plioc. gravel formed fr. droppings 
of floating, 220; inland, of Spits- 
bergen, 681-682 & pls. xli-xlii; 
rate of motion zbid., 686 & pl. xliv; 
sea-ice 2bid., action of, 687. 

Ice-age, Perm., 127-128. 

Ice-sheets in Spitsbergen, surface- 
phenom. of, 683-685 & pls. xlv— 
xlviii; drainage of, 685-686 & 
pl. xlvii. 

Ice-tunnels in Spitsbergen, 683 & 
pls. xlv—xlvi. 

Icebergs calved fr. King’s Glacier 
(Spitsb.), 686 & pl. xliv. 

Ightham (Kent), vertebrata fr. rock- 
fissure at, 419-429 & pl. xxviii. 

Igneous-rock boulder fr. Drift of 
Norton Heath, xvii; igneous bands 
in Cambr. of Malvern area, 158 e¢ 
segg. See also Diabase, Dolerite, ezc. 

Illenus Davisi, var. pseudolimbatus 
nov., 758. 

Tminifiri (Atlas Mts.), travertine nat. 
arch of, 199-201. 

Imintanut (Atlas Mts.), geol. of 
country betw. Sus and, 211-212. 
Impact-face, suggested equivalent for 

‘ stoss-seite,’ 683. 

Implements, stone, fr. Scaling, 
Ixxxviii ; fr. Thames Valley Drift in 
London, xcii; (?) in gravel at More- 
ton-in-the-Marsh, 220, 222. 

Index Map (Geol. Surv.), i, xiv. 

Index Slips issued w. Q. J., xi. 

Indurated shale, bobbin of, lxxxvi. 

een, beds in Lias, etc., 

8. 

Ingleton, see Dale Beck. 

Inlier, faulted, in Tideswell Dale, 239- 
250 figs. & pls. xix-xx (map & 
microse. sects.). 

International Geol. Map of Europe, vii. 

Interporiferous area, varieties of, in 
Mieraster-test, 499-501 & pl. xxxvi. 

Intrusive igneous rocks of Loch Awe 
region, 476-479 ; of 8. Tyrol, 568, 


GENERAL INDEX. 


[Nov. 1899, 


565-866, 567 et segg.; of Water- 
ford coast, 724 et seqq. 

Iron-ore deposits of Gellivaara & 
Kiirunayaara, 1; of Jebel Hadid, 
198. 

Ironstone foss. nodules fr. Lias, xcii ; 
ool. Ordov. ironst. in N. Anglesey, 
672. 


Jaspers contg. radiolaria in N.S.W., 
17 et segg., 38. 

Jebel Hadid, etc., see Hadid, ede. 

Jebelet or Little Atlas, metamorphic 
rocks of, 196. 

JENNINGS, A. V., on Geol. of Davos 
District, 381-412 figs. & pls. xxvi- 
XxvVli (map & sect.). 

Jenolan Caves (N.S.W.), 
rocks of, 17, 39. 

Jersey (Northern), see Sorel Point. 

Jonus, H. O., quoted, 764, 765. 

Jonus, Neviuix, quoted, 416. 

Jupp, J. W., receives Bigsby Medal 
for T. W. E. David, 1. 

Judicarian-Asta region, applic. of 
principles of torsion to, 625-632 w. 
map. 

JuKES-Brownge, A. J., on Oceanic 
Deposits of Trinidad, 177-181. 

Jurassic rocks, infold on Boe summit, 


605-606 fig. 


radiolar. 


Kayser, E., elected Kor. Member, 


Ixxxvil. 
Keal Hill (Yorks), limest.-knoll of, 
360. 


Keisley Limestone, knoll-struct. in, 
395-356. 

Kernnarp, A. S., quoted, 419. 

Kielerbach (Riigen), Chalk & Drift at, 
316-319 figs. 

Kiirunavaara (Sweden) iron-ore de- 
posits, i. . 

Kilchrenan (Argyll), altered rocks of, 
477 


Kilfarrasy (Waterford), Lr. Palzoz. 
of, 734-736 figs. 

Killelton Cove (Waterford), Lr. 
Palzoz. betw. Ballyvoyle and, 739- 
740. 

Kilmartin (Argyll), epidiorite of, 477. 

Kimeridge Clay, glaucon. limest. from, 
lxxxvil. 

Kine, W. W., on Perm. Conglom. of 
Lr. Severn Basin, 97-127 fig., 


ee eae 


stream w. moraine, 
pl. xlvu. 


Vol. 55. | 


King’s Quay (I. of Wight), <Amia 
from, 2, 4, 5, 7, 8. 

Kingswinford - Stourbridge area 
(Staffs), Middle Perm. of, 113. 

Kirxsy, J. W., quoted, 367-368. 

Kuzin, —, on Filtering Effect of Sand, 
Ixxvi. 

Knockaveelish Head (Waterford), 
exposures N. of, 725. 

Knockmahon (Waterford), 737-738 
w. sect. & list of foss. 

Knolls, limestone-, in Craven district, 
etc., 327-364 figs. & pl. xxiv. 

Knoll-structure, artif. reprod. of, 342 
fig., 343. 

Kollickerbach (Riigen), Chalk & Drift 
at, 318 figs., 319 [miscalled Wald- 
halle]. 

Krampass (Rigen), Chalk and Drift 
near, 312; see also Sassnitz, ete. 

Kiister’s Pit (Riigen), 314. 


Lady Hlizabeth’s Cove (Waterford), 
729, 730. 

Lakes, glacial, in Spitsbergen, 683. 

Laminated Carb. Limest. in Tideswell 
Dale, 240, 243, 248. 

Lamprophyres in Loch Awe region, 
479. 

Landslip areas, dangerous as reservoir- 
sites, lxx. 

Lanius collurio (?) fr. Ightham fissure, 
420. 


Lapwortu, C., quoted, 127, 633, 675; 
Wollaston Medal awarded to, xxxix. 

Laret (Davos), sect. on ry. near, 402; 
Lareter Bach, outcrops on E. side 
of, 404 fig. 

Lavas, felsitic, nr. Conway, 170-176 
w. map & sect. ; vesicular, in Tides- 
well Dale, 240 e¢ seqg., 247 & pl. 
xx (microse. sect.). 

Lavatory, cost of new, at Geol. Soc. 
Apartments, x. 

Leintwardine (Shropshire), Hucladia 
Woodwardi, sp. nov. from, 694-696 
fi 


Ss. 

api isdnaree australe-beds & their 
relation. to radiolar. rocksof N.S. W., 
17, 19, 21 e¢ segg., 61, 64. 

Leptena-limestone of Dalecarlia, etc., 
knoll-struct. in, 357. 

Lepus cuniculus fr. Ightham fissure, 
422. 

variabilis, do. do., 421. 

Lewisian Gneiss Series in Glenelg, 
375, 380. 

Lias betw. Rugby and Catesby, 65-88 
figs. w. list of foss.; ironst. foss. 
nodules fr. Lias, xlii; L. of Boe 
summit, 606. 


GENERAL INDEX. 


783 


Library & Museum Committee, annual 
report, Xlli—xiv. 

Library, list of donors to, xv—xx. 

Liebenerite-porphyrite of S. Tyrol, 
585. 

Liesiscu, Tu., elected For. Oorr., v. 

Limekiln Wood (Cheshire), sect. deser. 
& fig., 552-554. 

Limestonesin radiolar.seriesof N.S.W., 
18, 20 et segg., 40; glauconit., in 
Kim. Clay, Ixxxvii; magnesian, 
etc. in N. Anglesey, 668-669; see 
also Siliceous, Tufaceous, ete. 

Limestone-knolls in Craven district, 
etc., 327-364 figs. & pl. xxiv. 

Lindridge (Shropshire), Perm. near, 
table i, face. 108. 

Lnosphera (2) sp. ind., 44 & pl. viii. 

Lithodendron-kalk of Davos district, 
386, 400, 403, 409. 

Llanbadrig (Anglesey), sect. at Ogof 
Gynfor near, 648; sect. in quartz- 
knob at Ll. Point, 653; crushed 
rocks of, 664; altered limest. of, 
669. 

Llandeilo (Upper) in N. Anglesey, 
640, 641 e¢ segg.; Lland. age of 
strata on Waterford coast, 770- 
(wae 

Llandovery sandstone-pebbles in Mid- 
dle Perm. conglom., 119-120 & 
tables iii-iv; Ll. sandst.-débris on 
Hollybush Hill, 143. 

Llanfair-y nghoruwy (Anglesey), con 
torted phyllites near, 651 fig. 
Llanfechell Grits in N. Anglesey, 

637. 

Llyn Dinam (Anglesey), gabbro of, 
277, 293. 

Llyn Penrhyn (Anglesey), gabbro of, 
277; actinolitic rock of, 295. 

Loch Awe Series, 473, 474-475 et¢ 
seqgg.; progressive metamorphism in, 
482-486. 

La@winson-Lessine, F., elected For. 
Corr., lxxxvii. 

Londonderry & Tyrone granites, age 
of, 273-275 fig. 

Lucy, W. C., obituary of, lxiii. 

Ludlow (Lr.) of Leintwardine, Eu- 
cladia Woodwardi, sp. nov. from, 
694-696 figs.; L. L. of (?), Myria- 
stiches gigas, gen. & sp. noy. from, 
700-701 fig. 

Lutra vulgaris (2) fr. Ightham fissure, 
428 


Lyrtt Medal & Fund, list of recipients, 
XXX, 


Magnetite of Gellivaara & Kiiruna- 
vaara, i. 


784 


Marrtanp, A. G., pres. map of Collie 
coalfield (W. A.), Ixxxvi. 

Makran coast (Pers. Gulf), Mioe. 
Cardium (?) from, vi. 

Malvern district, Huthemon igerna, 
gen. & sp. nov. fr. Wenlock Limest. 
of, 696-699 figs. 

Malvern Tunnel, sect. along line of, 
150; theoret. restor. of same, 156. 
Malverns (8.), geol. struct. of, 129-169 

figs. & pls. xiii-xv (map, etc.). 

Mammalian humerus, see Hemiomus. 

Man, I. of, limest.-knolls comp. w. 
those of Yorks, 363. 

Maxcovu, J., obituary of, lvi. 

Marmorized Carb. Limest. in Tides- 
well Dale, 239, 240, 242 et segq., 248. 

Marossa (Atlas Mts.), geol. of country 
between Sus and, 211 w. sect. 

Marr, J. E., on Conglom. nr. Mel- 
merby (Cumberland), 11-13 fig.; 
on Limest.-Knolls in Craven Dis- 
trict, etc., 327-358 figs. & pl. xxiv. 

Martins (Malverns), geol. struct. of 
district, 161-164. 

Mataura (N.Z.), rhyolite of, 462-463. 

Matizy, O. A., exhib. schorl-rock 
pebbles, viii; on Geol. of N, Angle- 
sey, 635-675 figs. 

Mauritius, Pteropus-bones from, xc. 

May Hill Sandstone of Midsummer 
Hill, etc., 1389 et segg.; of White- 
leaved Oak, etc., 157 et segg.; of 
Bronsil district, 165. 

May Hill Sandstone escarpment, 166- 
168. 

McManoy, ©. A., Lyell Medal awarded 
to, xlvi. 

Megalaspis, sp. a (Tramore Limest.), 
755-756. 

, sp. y (Tramore Limest.), 756. 

Megalodon triqueter, occurr. in Sella 
massive, 600, 605. 

Megalosauroid jaw, fr. Rhetie nr. 
Bridgend, 89-96 & pl. x. 

Megophagi, new name for Apelmato- 
zoa, 715, 

Meles taxus fr. Ightham fissure, 428. 

Melmerby (Cumberland), conglom. 
nr., 11-15 fig. 

Mendola Dolomite, 567-569, 571 e¢ 


seqq. 

Men Highlands, source of Middle 
and Upper Perm. rock-materials, 
127. 

Mercury Bay (N.Z.), rhyolites of, 
449, 450, 453-454 & pl. xxxii 
(microse. sect.). 

Mesites, ambulacr. struct. of Palgo- 
discus comp. with, 706-707. 

Metamorphic rocks of 8. Morocco, 


GENERAL INDEX. 


[Nov. 1899, 


196; of Loch Awe region, 470-493 
Ww. map. 

Metamorphism, progressive, in Dal- 
radian of Loch Awe region, 470- 
493 w. map. 

Mrver, O. A. J., quoted, 543. 

Micxkwirz, A. von, quoted, xci. 

Micraster, anal. of genus, 494-546 & 
pls. xxxv-xxxix. 

cor-anguinum, 538 & pls. xxxv- 

xxxix; var. datior nov., 539-540 & 

pls. xxxv—xxxvil. 

cor-bovis, 518-524 & pls. xxxv- 

REI, 

cor-testudinarium, 534-538 & 

pl. xxxv. 

Lesket, 525-528 & pls. xxxv- 

XXxvili; pass. form. betw. M. pre- 

cursor and, 528-530 & pls. xxxv- 

XXXVIIL. 

precursor, new group, 496, 530- 
534 & pls. xxxv—xxxix; pass. form. 
between M. Leskei and, 528-530 & 
pls. xxXxV-xXxxVlil. 

Microfelsite=rudimentary form of de- 
vitr. glass, 466. 

Microfelsitic structure in Hauraki 
rhyolites, 452 e¢ segg. & pls. xxx1i— 
Xxxiv (microsc. sects.). 

Microperthitic structure in orthocel. of 
Jersey granite, 433, 435. 

Microtus arvalis fr. Ightham fissure, 
425, 

nivalis (2) do. do., 425. 

Mid-Glacial Sands & Gravels, betw. 
Rugby & Catesby, 82. 

Midsummer Hill (Malverns), geol. 
struct. of, 138-142, 151 ed segq. figs. 
& pl. xiii (nap); view of, pl. xv. 

Millom (Cumberland), knoll-struct. in 
Coniston Limest. of, 855, 356. 

Millstone Grit of Lancaster Fells, 
horiz. slickensidg. in, 353. 

Mitne-Hpwarps, A., elected For. 
Memb., v. 

Miltsin, see Asif Sig. 

Mineaye, J. C. H., chem. anal. of ra- 
diolar. rocksof Tamworth(N.S.W.), 
31-32. 

Miocene Cardium (2) fr. Ormara, vi; 
Mioc. rocks in S. Morocco, 194, 
195; Mioe. vole. rocks of N.Z., 451. 

Misfiwa (Atlas Mts.), geol. of, 205. 

Mittelbildungen (Trias), of Davos dis- 
trict, 387-389. 

Méen (Baltic), relats. of Chalk & 
Drift in Rigen and, 305-326 figs. 
Monckton, H. W., exhib. specims., 

Ixxxvi. 
Monian age of Green Series discussed, 


639, 640, 678. 


Vol. 55. ] 


Monotreme (?) footprints fr. Trias of 
Stourton, Ixxxix. 

Monte Sief (S. Tyrol), normal fault 
of, 620; analogy w. Rodella Hill, 
623-624 ; sect. to Buchenstein 
Valley, 586. 

Monticulipora (Diplotrypa) petropoli- 
tana, 763 

Moreton-in-the-Marsh (Gloucester), 
gravel at, 220. 

Morocco (S8.), geol. of, 190-212 w. 
sects. 

Mullion Parish (Cornwall), radiolar. 
in chert fr. Chypons Farm, 214- 
219 & pl. xvi. 

Mourcuison Medal & Fund, list of 
recipients, xxix. 

Mus Lewisi (= M. Abbotii) fr. Ightham 
fissure, 424-425. 

Muschelkalk of 8. Tyrol, 567 et segg. 

Mustela putorius fr. Ightham fissure, 
425, 

robusta, do. do., 425-427 & pl. 

XXVill. 

vulgaris, do. do., 425. 

Mylonized rock of Glenelg, etc., 374- 
375. 

Mynachdy (Anglesey), Ordov. foss. 
found N.W. of, 640. 

Mynydd Mechell Schists in N. Angle- 
sey, 637, 651. 

Mynydd-y-Garn (Anglesey), faulted 
inlier of, 649-650. 

Myriastiches gigas, gen. & sp. nov., 
700-701 fig. 

Myriastichids, fam. nov., 701. 


Names of Fellows in arrear read out, 
X¢, XCil. 

Naparima Marls, success. & geol. re- 
lats. of, 177-189 w. map & vert. 
sects. 

Nariva Beds, their place in the Tri- 
nidad rock-success., 180-181, 187; 
outcrops deser., 182, 183; Hoc. age 
of, 188. 

Neilson, Mt. & Glacier (Spitsbergen), 
689 & pls. xlii-xliii. 

New Inverawe (Loch Awe), phyllites 
of, 480. 

‘New South Wales (Australia), Palzoz. 
radiolar. rocks of, 16-37 fig. w. 
anal. & pls. ii-vii (map & sects.) ; ra- 
diolaria in same, 38-63 & pls. viii-—ix. 

Newron, E. T., on Amia fr. Oligocene 
of I. of Wight, 1-10 & pl. i; on 
Megalosaur. Jaw fr. Rhetic nr. 
Bridgend (Glamorgan), 89-94 & 
pl.x; Add. Notes on Vertebr. Fauna 
of Rock-fissure at Ightham, 419- 
429 & pl. xxviii. 


GENERAL INDEX, 


785 


Newtown Head (Waterford), Lr. 
Paleeoz. of, 721-725 w. sect. & lists 
of foss. 

Nicuotson, H. A., obituary of, lxiv. 

Nodular felsite, of Bodlondeb, 171; of 
Waterford coast, 763-765 w. chem. 
anal.; nod. limest. in Tideswell 
Dale, 248. 

Nodules, phosphatic, in Lr. Lias nr. 
Rugby, 68; various, in Middle Lias 
ibid., 73, 87; ironstone fossilif, in 
Lias, xcli. 

Nordenskjéld Glacier (Spitsbergen), 
Archzean moraine-material of, 684 
& pl. xlviii. 

‘ Northern Complex’ in Anglesey, 638. 

Northfield (Staffs), Upper Perm. of, 
116-117. 

Norton Heath (Essex), igneous boulder 
fr. Drift of, lxxxvil. 

Number of Fellows, For. Memb. & 
For. Corr., 1x—x, xxi. 

Nunatakkr, in Spitsbergen, flora of, 
682; effect on englacial material, 


684 & pl. xlvi. 


Oak, foss., fr. Chepstow, iv. 

Oax ey, C., obituary of, lxvi. 

Oberdiluvium of Rigen, see Drift. 

Obersee (Esthonia), pyramid-pebbles 
fr. shore of, xci. 

Obsidian, devitrified, of Bodlondeb, 
171, 173; of Hauraki, 453, 458- 
459 & pl. xxxii (microse. sects.). 

Oceanic deposits of Trinidad, 177-189 
w. map, vert. sects. & chem. anal. 

Ocitviz, M. M., on Torsion-struct. of 
Dolomites, 560-633 figs. & pl. xl 


(map). 

Ogof Gynfor (Anglesey), Ordov. foss. 
of, 640; sect. at, 648. 

Old Red Sandstone conglom. unr. 
Melmerby, striated by  earth- 
movemt., 11-15 fig.; O. R. 8. peb- 
bles in Perm. conglom., 121-122 & 
table iii; O. R. S. & granite-junct. 
in Tyrone & Londonderry, 273- 
275 fig. 

Oligocene of I. of Wight, Amia from, 
1-10 & pl. i. 

Olivine-dolerite of Tideswell Dale, 
245-246, 248-249 & pl. xx (microsce. 
sects.). 

Olivine-melaphyre of 8. Tyrol, 585. 

Omahu (N.Z.), rhyolites of, 451- 
453, 455-457 & pls. xxxii-xxxiv; 
chem. anal. of same, 467. 

Ophicaleareous Grits of Davos dis- 
trict, 394. 

Ophicalcite of Anglesey, 277 e¢ segq., 
289-290. 


786 


Ophiocistia, ord. nov., 692, 700. 

Ophiolite (altered limest.) of Bally- 
douane Bay, 738-739. 

Ophitic diabase of Northern Jersey, 
see Diabase. 

Ophiuroidea, Silur., in Oxf. Univ. 
Mus., 692-715 figs. 

Ordovician in N. Anglesey, 638, 
672-673 fig.; relat. of same to 
Green Series zbid., 638-667 figs. ; 
do. to Northern Complex b7d., 673- 
674; microsc. char. of Ord. rocks 
ibid., 676-677 ; Ord. of Waterford 
coast, 718-772 figs. & pl. xlix (foss.). 

Ormara (Makran coast), Mioc. Car- 
dium (?) from, vi. 

Ormerod, H. M., obituary of, lxvi. 

Orogenic movements, sce Harth-move- 
ments. 

Orthis argentea, 760. — 

— Bailyana, Monian (?) age of, 
discussed, 688-639, 640, 678. 

Caraustt regarded as a dwarf 

var. of O. calligramma, 641. 

(Orthisina 2) crispa, 760-761. 

Orthisina ef. squamata, 760. 

Orthoclases in Jersey granite, etc., 
433, 435, 436 fig. 

Osborne Beds, Ama from, 2, 4, 5, 7,8. 

Otterburn Valley (Yorks), limest.- 
knolls of, 340; pseudostromatism (?) 
in limest. of, 341 fig.; folded & 
broken limest. of, 545 figs. 

Overthrusts of Cherz Hill, 584; 
oblique faultg. across same, 585 ; 
overthr. in Pieve area, 587; peri- 
pheral, of Sella, at Griiner Fleck, 
etc., 593-596, 601; N. & S. fold- 
ares in same, 602-604 ; overthr. of 
Pordoi Pass, 596; torsion of same 
at Bova Alp, 599; peripheral, round 
S. & W. of Sett Sass, 617, 618. 

Oxford Univ. Museum, Silur. echinoid. 
& ophiuroid. in, 692-715 figs. 


Paleodiscus ferox, 701-705 figs. 

Paleolithic implemts. etc. fr. Thames 
Valley Drift in London, xlii. 

Paleozoic radiolar. rocks of N.S.W., 
16-37 & pls. ii-vil; absence of 
Paleoz. in Moroccan Atlas, Nile 
Valley, etc, 2138; Lr. Palzoz. 
strata of Co. Waterford, 718-772 
figs. & pl. xlix (foss.). 

Pappichthys, see Amia. 

Park, J., on Rhyolites of Hauraki 
Goldfields, 449-451 & pl. xxx 
(map). 

Parkinson, J., on Intrus. of Granite 
into Diabase at Sorel Point, 480-447 
figs. & pls, xxix-xxx (microse. sects. ). 


GENERAL INDEX. 


[Nov. 1899, 


Parsenn-Furka Pass (Davos), sect. H. 
of, 407. 

Partnach Schiefer of Davos district, 
389. 

Pracu, B. N., Murchison Medal 
awarded to, xliii ; quoted, 642, 
647. 

Pebbles, of Middle Perm. conglom., 
composit. of, 118-123 & tables iii- 
iv; striation of, non-glacial, 11-15, 
128 ; pebbles of schorl-rock in Drifts 
of 8. & E. Engl., 220-228. 

Pegmatites, red, in Ben Cruachan 
area, 485. ° 

Pendleside Limestone, correl. of, 350, 
362. 

Pendock’s Grove (Malverns), geol. 
struct. of district, 157-160. 

Penrhyn (Anglesey), coast-sect. at, 
660; rock-face, showg. relics of 
stratif. in crush-conglom., 662 fig. 

Penrhyn-Fadog (Anglesey), variolit. 
serpentine near, 283; diallage-rock 
& enstatite-rock near, 290, 291; 
actinolite-rocks near, 292, 295. 

Penterfyn (Anglesey), Dicranograptus- 
beds of, 640, 672. 

Penton Linns (Dumfries), Céenodonta 
pentonensis, sp. nov. from, 368-370 
& pl. xxv. 

Peri-Adriatie torsion-curves, 631-632 
w. Map. 

Perlitic cracks in quartz, Waikino 
rhyolite, 461 & pl. xxxiii (microse. 
sect.) ; perlit. struct. in Waterford 
felsites, 721, '763, '764. 

Permeable rocks, to be avoided in 
reservoir-sites, lxxi. 

Permian conglomerates of Lr. Severn 
Basin, 97-128 w. tables i-iii & 
pls. xi-xii (maps). 

Permo-Carboniferous rocks in Spits- 
bergen, 688, 689. 

Permo-Triassic age of movemts. wh. 
prod. limest.-knolls of Craven 
district, etc., 354. 

Perry Hill (Staffs), Perm. breccia of, 
117. 

Pescosta-Corvara Fault (8S. Tyrol), 
573-574. 

Phacops Baily, 750. 

Brongniarti, 749. 

—— Jamesii, 749. 

truncato-caudatus, '750. 

Philley Brook (Shropshire), Perm. 
near, table i, facg. 108. 

Puiuirs, J. St. J., quoted, 273. 

Phosphatic nodules, in Lias nr. 
Rugby, 68. 

Phyllites of Ardrishaig Series, 473 ; 
progressive metamorphism of same, 


Vol. 55.] 


480-482; contorted phyll. in N. 
Anglesey, 651 fig. 
Pian de Sass (S. Tyrol), 598-599. 
Picrodon, generic value discussed, 93 
et seqg. 
Pieve area (S. Tyrol), overthrusts in, 
87. 


Piping-down of sand, etc. into Chalk, 
325, 326. 

Pissadoi Ravine (S. Tyrol), structur. 
significance of, 591. ° 

Pirrman, HK. F., & Davin, T. W. E., 
on Palxoz. Radiolar. Rocks of 
N.S.W., 16-37 fig. w. anal. & 
pls. ii-vii (map & sects.). 

Pitzculatsch (S. Tyrol) fault-dyke, 
567 ; exposures at, 591-592. 

Plagiacantha australis, sp. nov., 56 & 
pl. ix. 

Plagioclase, corroded, lying in uni- 
form felsp. subst., 456 fig.; pre- 
ponderance in Hauraki rhyolites, 
466. 

Plagioclinal struct. of Midsummer 
Hill, 155. 

Plagoniseus colligatus, sp. nov., 56 & 
fi 


cristatus, sp. nov., 56 & fig. 

simplex, sp. nov., 56 & fig. 

— (2) vetustus, sp. nov., 57 & fig. 

—— (2) sp., 57 & fig. 

Plas-coch (Anglesey), serpentine, etc. 
of, 280, 284, 297. 

Plateau of S. Morocco, 196-198. 

Pleistocene vertebrata fr. Ightham 
fissure, 419 ez segg. 

Pliocene rocks in S. Morocco, 194, 
195 ; (?) gravel at Moreton-in-the- 
Marsh, 220; Plioc. vole. rocks of 
New Zealand, 449, 451. 

Plon Fault (S. Tyrol), 567. 

Polishing of rocks by wind-action, i, 
XC-XCi. 

PotiarD, W., & Croven, C. T., on 
Spinel & Forsterite fr. Glenelg 

“. Limest., 372-379 w. chem. anal 

Polygenic breccia of Davos district, 
396 fig., 397. 

Porambonites intercedens var. /filosa, 
761. 

Pordoi Pass overthrust (S. Tyrol), 
596-597 ; torsion of same at Bova 
Alp, 599. 

Porphyrites in Atlas Mts., 207 ; (?) in 
Anglesey, 294; in Loch Awe re- 
gion, 478, 479. 

Porter, D. A., quoted, 37. 

Porth Llanlliana (Anglesey), ‘ quartz- 
knob’ of, 670; purple band in 
cleaved grits & conglom. W. of, 
673 fig. 


GENERAL INDEX. 


787 


Porth Newydd (Anglesey), horizont. 
faults in cliff N. of Ordov. boundary, 
654 fig. ; disrupted grit-courses in 
Ordov. black shales, 656 fig., 666. 

Porth Padrig (Anglesey), Ordoyv. foss. 
at, 639, 640. 

Porth y Corwgl (Anglesey), Ordov. 
crush-conglom. in, 660-661. 

Porth yr Ebol (Anglesey), sect. in, 
645. 

Post-Ordovician age of last period of 
movemt. in N. Anglesey, 667. 

Pralongia (S. Tyrol), geol. of, 613- 
623 w. maps; Pr.-Soraruaz dia- 
gonal fault, 585, 615; Pr. & 
Castello thrust-plane, 619-620. 

Pre-Devonian age of Tyrone & Lon- 
donderry granites, 273-275 fig. 

Pre-Llandeilo age of Green Series, 
etc. in N. Anglesey, 650, 674. 

Pre-Silurian age of Anglesey ser- 
‘pentines, 301. 

Prelongei, see Pralongia. 

Pressure, effects of, shown in Anglesey 
rocks, 300-301 ; in knoll-limestones 
of Craven district, etc., 331 et seqq. 

Pretender Range (Spitsbergen), ice- 
tunnels formed against, pl. xlvi; 
rock-avalanches from, 688. 

Princestown (Trinidad), Globigerina- 
marls, etc. of, 182-183. 

Protamia, see Amia. 

Protocidaris sp., 709-710. 

Pseudo-fossils fr. Silur. of Tipperary, 
li. 

Pseudostromatism in limest. of Craven 
district, etc., 338, 341 fig. 

Pteropus-bones fr. Mauritius, xc. 

Pumice-tuff of Waikino, 457 & 
pl. xxxiv (microse. sect.). 

Pwll-pillo (Anglesey), variolit. ser- 
pentine near. 282 fig., 283, 286. 

Pyramid-pebbles, xc-xci. 

Pyrites in vole. ash betw. Ashbourne 
& Crake Low, 2383, 234. 


‘Quartz vermiculé’ in granite, ete. of 
Northern Jersey, 433, 438-439. 

‘ Quartz-blows’ in Hauraki district, 
461, 463. 

‘ Quartz-knobs’ in N. Anglesey, 669- 
672 fig., 678 et segg.; microse. 
struct. of same, 677. 

Quartz-porphyries in Loch Awe 
region, 478, 479; of Ballyvooney 
Harbour, 739. 

Quartzites in Atlas Mts., 202, 203; 
granulitic, of Glenelg, etc., 374-375; 
q. in N. Anglesey, 669-672 fig., 678 
et segg.; microsc. struct. of same, 


677. 


788 


Radiating-points of ice-sheet in 
Spitsbergen, 682 & pl xii 
(map). 

Radii of torsion, 604. 

Radiolaria in Devon. rocks of N.S.W., 
38-63 & pls. viii-ix; in chert fr. 
Chypons Farm, Mullion Parish 
(Cornw.), 214-219 & pl. xvi. 

- Radiolarian Paleoz. rocks of N.S.W., 
16-87 fig. w. anal. & pls. ii-vii (map 
& sects.); Tertiary rocks of Trinidad 
& Barbados, 181 et segg. w. chem. 
anal.; radiolar. hornst. of Davos 
district, 394-395. 

Raggedstone Hill (Malverns), geol. 
struct. of, 131-138, 151 et segg. 
figs. & pl. xiii (map); view of, 
pl. xiv; sects., 186, 144, 147. 

Raheen (Waterford), Lr. Palzoz. of, 
721-725. 

Raheen Shales, 741, 742; correl. w. 
Orthis argentea-zone of 8S. Wales, 
769. 

Raisin, Miss C. A., & Bonney, T. G., 
on Serpent. & Assoc. Rocks in 
Anglesey, 276-302 figs. & pl. xxiii 
(mierose. sects. ). 

Rauchwacke (Upper) of Davos dis- 
trict, 387 ; (Lower) ibzd., 389. 

Raw, F., quoted, 567. 

Record of Geological Literature, xi. 

‘Red-and-green Schists’ of Davos 
district, 393-394. 

Resp, F. R.C., on Lr. Palseoz. Bedded 
Rocks of Co. Waterford, 718-772 
figs. & pl. xlix (foss.); quoted, 
305, 306. 

Reef-breccias, 329 ; reef-knolls, 329 e¢ 
segg., 339, 361 et segg. 

Reference, Committee of, xi—xii. 

Rui, O., quoted, 2. 

Remopleurides Portlocki, sp. nov., 
746 & pl. xlix. 

Saltert, sp. nov., 747 & pl. xlix. 

—— tuberculatus, sp. nov., 748 & 
pl. xlix. 

Reraya, Wad (Atlas Mts.), geol. of, 
206-207 w. sect. 

Reservoirs, geol. considerations conn. 
with, Ixix. 

Rhetic of Bridgend, Zanclodon cam- 
brensis from, 89-96 & pl. x; Rh. 
of Davos district, 385-386. 

Rhatikon (Davos), outcrops on H., 
404 fig. 

Rhodosphera Ruesti, sp. nov., 44 & 
pl. viii. 

Rhosbeirio Shales in N. Anglesey, 
637. 

Rhoscolyn Parish (Anglesey), ser- 
pentine, gabbro, etc. of, 278-280. 


GENERAL INDEX. 


[Nov. 1899, 


Rhyd-bont (Anglesey), variolit. ser- 
pentine near, 282 fig. 

Rhynchonella Cuviert-zone, anal. of 
Micraster betw. M. cor-anguinum- 
zone and, 494-547 & pls. xxxy— 
66.0 

Rhyolites, tufaceous, of Bodlondeb, 
173; of Hauraki goldfields, 449- 
469 w. chem. anal. & pls. xxxii-— 
Xxxiv (map & microse. sects.) ; 
altered, of Davos district, 398. 

Rhyolite-tuff of Bodlondeb, 174. 

Ricutuoren, F. von, quoted, 560, 
561, 632. 

Richthofen Reef (S. Tyrol), 617, 618. 

Ridney Hill (Shropshire), Perm. at, 
table ii [p. 109]. 

Rosinson, O., quoted, 764, '765. 
Rock-sculpturing above snow-line in 
Spitsbergen, 688-689 & pl. xviii. 
Rodella Hill (8. Tyrol), analogy w. 

Monte Sief, 623-624. 

Reaper, C., quoted, 365, 370. 

Romsley (Shropshire), Perm. at, table 
ii [p. 109], 110. 

Rows, A. W., Anal. of Genus M7- 
craster, as det. by rigid zonal col- 
lectg. fr. zone of Ah. Cuviert to that 
of M. cor-anguinum, 494-546 & 
pls. xxxv—xxxix. 

Rugby (Warwick), sects. betw. Catesby 
and, descr. & fig., 65-88 w. list of 
foss. 

Riigen (Baltic), relats. of Chalk & 
Drift in Moen and, 305-326 figs. 

Ruon (8. Tyrol) rock, 571-573. 

Rutey, F., on Felsitic Lavas & Tufts 
nr. Conway, 170-175 w. map & 
sect.; on Microscop. Char. of Rhy- 
olites of Hauraki Goldfields, 451- 
467 & pls. xxxli-xxxiv (microse. 
sects.). 

Rutsch-striz, see Slickenside-striz. 


Saffi (S. Morocco), Tertiary rocks of, 
95. 

Salt-springs in Lr. Cret. of 8. Mo- 
rocco, 197, 201. 

Sauter, A. E., exhib. specims., lxxxvii, 
lxxxviii, xci; on Occurr. of Schorl- 
rock Pebbles fr. S.-W. Engl. in 
S. & E. Engl. (abs.), 220-221. 

San Fernando Beds, 178 e¢ segq.; 
Oligoc. age of, 188. 

Sand, filtering effect of, lxxvi. 

SANDBERGER, F’, von, obituary of, lvii. 

Sandskredsfald (Moen), sect. deser. 
& fig., 309. 

Sandybrooke cutting (Derby), 225. 

Sassnitz (Riigen), Chalk & Drift near, 
312-316 ; sect. nr. ry.-station, 315. 


Vol. 55. | 


Scaleber (Yorks), knolls near, pl. xxiv 
facg. 339; folded limest. in shale 
near, 345, 346 fig., 347. 

Scaling (Yorks), stone-implemt. from, 
Ixxxvili. 

Schlern Dolomite, age of, 561-562 ; 
exposures of, 593, 595 ez seqq. 

Schorl-rock pebbles, orig. of, in 
Drifts of 8. & HB. Engl., 220-223. 

Sea-ice off Spitsbergen, action of, 687. 

Sedgley-Baggeridge area (Staffs), 
Middle & Upper Perm. of, 114, 115. 

Srsiuy, H.G., on Monotreme(?) Foot- 
print fr. Trias of Stourton, lxxxix ; 
-on Hemiomus major, gen. & sp. nov. 
fr. Tonbridge, 413-415 figs.; on 
Evid. of a Bird fr. Wealden Beds 
of Ansty Lane, Cuckfield, 416-418 
figs. 

Selenite, in Lias nr. Catesby, 77. 

Sella massive (S. Tyrol), geol. of, 590- 
612 w. sects. & pl. xl (map). 

Serpentine, belt of, in N.S.W., 18- 
19; variolitic, etc., & assoc. rocks 
in Anglesey, 276-304 figs. & pl. 
xxiii (microse, sects.); serp. of 
Davos district, 891-393. 

Servino=shaly Verrucano, 389, 395. 

Sett Sass (S. Tyrol), geol. of, 613- 
623 w. maps. 

Settle (Yorks), limest.-knolls near, 
338, 339 & pl. xxiv. 

Severn Basin, Lr., Permian conglom., 
of, 97-128 w. tables i-iii & pls. xi- 
xii (maps). 

Sewage-farms, best sites for, lxxv. 

Shear-and-contact breccia of Buchen- 
stein, ete., 567-569, 577, 584. 

Sheepwalks (Enville), Perm. of, 105 
& table i. 

Shell-rocks, Tertiary, in 8. Morocco, 
194, 195. 

Suerpory, C. D., report on registra- 
tion work in Museum, xiv; quoted, 
544, 

Shropshire (S.E.), Middle & Upper 
Perm. of, 100, 102-111, & pl. xi 
(map). 

Siliceous organisms, replacem. by carb. 
of lime, 716-717. 

Silicified limestones of Stockdale 
Valley, 341. 

Sill (& faulted inlier) in Tideswell Dale, 
239-250 figs. & pls. xix-xx (map & 
microse. sects.); sills of Vallbach, 
569-570. 

Silurian foss. found in Middle Perm. 
conglom., list of, 124; pseudo-foss, 
fr. Tipperary, ii; Silur. echinoid. 
& ophiuroid. in Oxf. Univ. Mus,, 
692-715 figs. 


GENERAL INDEX. 


789 


Simonseat (Yorks), swallow-holes on, 
360-361. 

Skelterton (Yorks), limest.-knoll of, 
359. 

Skipton (Craven), limest.-knolls below, 
359-361. 

Slickenside-strie, 13, 128; in 
Draughton Quarry rocks, 334. 

Socach (Dalmally), altered rocks of, 
481 et segq. 

Solfataric action in N.Z., 450, 464. 

Souuas, W. J., on Silur. Hehinoid. & 
Ophiuroid, in Oxf, Uniy.Mus., 692- 
715 figs.; on Occurr. of Sponge- 
spicules in Carb. Limest. of Derby- 
shire, 716-717. 

Sopwirtn, T., obituary of, lxvi. 

Soraruaz-Pralongia diagonal fault 
(S. Tyrol), 585, 615. 

Sorsy, H. C., presents his portrait, 
Ixxxvil. 

Sorel Point (Jersey), intrus. of granite 
into diabase at, 430-448 figs. & 

_ pls. xxix-xxx (microse. sects.). 

ee ae clypeata fr. Ightham fissure, 

0. 


Spermophilus erythrogenoides from 
Tghtham fissure, 422-424 & pl. 
XXVili. 

Spherozoum sp., 43 & pl. viii. 

Spherulitic serpentines, see Variolitic ; 
spherul. struct. in Hauraki rhy- 
olites, 451 e¢ segg. & pls. xxxii- 
xxXxlv (microsc. sects.). 

Spinel fr. Glenelg Limest., 372-380 
w. chem. anal. 

Spitsbergen, glacial phenom. of, 681- 
691 & pls. xli-xlvili (map, etc.). 

Sponge-spicules in radiolar. rocks of 
N.S.W., 60-61; in Carb. Limest. 
of Derbyshire, 716-717. 

Spongocelia citreum, gen. & sp. nov., 
52 & pl. ix. 

oliva, sp. noy., 52 & pl. ix. 

Spongodiscus acinus, sp. nov., 54 & 
ple ix 

cribrarius, sp. nov., 54 & pl. 


1X. 


punctus, sp. nov., 54 & pl. ix. 

—— seutulatus, sp. nov., 55 & pl. ix. 

Spores lens, sp. nov., 55 & 

pm 

Spongoplegma australe, sp. nov., 44 & 
pl. viii. 

Spongotripus fenestratus, sp. nov., 55 
& pl. ix. 

patella, sp. nov., 55 & pl. ix. 

St. Margaret’s (Cheshire), pyramid- 
pebble found near, xe. 

Ste. Madeleine (Trinidad), Nariva 
Beds, etc. of, 182, 183, 


790 


Staffordshire (N.), Anthracomya calci- 
fera, sp. nov. fr. Upper C.M. of, 
365-366 & pl. xxv; Carbonicola 
Vinti fr. same, 867-368 & pl. xxv. 

Staffordshire (S.), Middle & Upper 
Perm. of, 101, 111-118 & pl. xii 
(map). 

Staurodruppa, gen. nov., 51. 

—— Foxii, sp. nov., 217 & pl. xvi. 

nana, sp. nov., 52 & pl. ix. 

—— nucula, sp. nov., 52 & pl. ix; 
216 & pl. xvi. 

prelonga, sp. nov., 51 & pl. ix. 

Staurolonche Davidi, sp. nov., 46 & 
pl. viii. 

laterna, sp. nov., 47 & pl. viii. 

scitula, sp. nov., 47 & pl. viii. 

—— tenella, sp. nov., 47 & pl. viii. 

Staurolonchidium obliquum, sp. nov., 
47 & pl. viii. 

Staurosphera (?) ornata, sp. nov., 
46 & pl. viii. 

pusilla, sp. nov., 46 & pl. viii. 

Stebden Hill (Yorks), limest.-knoll of, 
359. 

Sticky Keep (Spitsbergen), diabase- 
boulders on, 689. 

Stirrz, A. W., on Mioc. Cardium (?) 
fr. Ormara, Vi. 

Stigmosphera echinata, sp. nov., 215 
& pl. xvi. 

Stigmospherostylus inequalis, sp. nov., 
216 & pl. xvi. 

Stockdale Valley (Yorks), limest.- 
knolls of, 339, 341. 

Stormy Down (Glamorgan), Zan- 
clodon cambrensis from, 89-96 & 

Ie axe 

Stoss-seite, see _Impact-face. 

Stour Valley district (Staffs), Middle 
& Upper Perm. of, 112-115 & pl. 
xii (map). 

Stourbridge-Kingswinford (Staffs), 
Middle Perm. of, 113. 

Stourton (Cheshire), monotreme (?) 
footprint fr. Trias of, lxxxix. 

StraHAN, A., exhib. photogr. plates 
(Purbeck), vii. 

Streams, on surface of ice, in Spits- 
bergen, 685 & pl. xlvii; englacial, 
ibid., 685-686 & pl. xlvii. 

Streifen Schiefer of Davos district, 
389. 

Strela Fold (Davos), 403-405 figs. & 
pl. xxvii (sect.). 

Striation of pebbles by earth-move- 
ment, 11-15, 128. 

Strike, Tertiary, superposed upon 
Triassic, in 8. Tyrol, 590. 

Strike-torsion, 612; round Pralongia 
& Sett Sass, 616; at Fassa, 627-628. 


GENERAL INDEX. 


[Nov. 1899, 


Stubbenkammer (Rigen), Chalk & 
Drift near, 312, 313. 

Stuores (S. Tyrol), bundle of diagonal 
faults, 615-616. 

Stylosphera obtusa, sp. noy., 49 & 
pl. viii. 

vetusta, sp. nov., 46 & pl. viii. 

Sus (S. Morocco), sects. to Amsmiz 
across Jebel Tezah, etc. and to plain 
of Morocco across Jebel Ogdimt, 
208; geol. of country betw. Imin- 
tanut and, 211-212. 

Swallow-holes on Simonseat, 360- 
361. 


Taghnowt (S. Morocco), sect. to Tizi 
Likumpt, 204. 

Talc-schist in Anglesey, 297-300; 
tale-granite of Davos district, 398. 

Taleren (Moen), Drift & Chalk of, 
308. 

Tamworth district (N.S.W.), Palzoz. 
radiolar. rocks of, 17, 19 e¢ segq. 
& pls. ii-vii (map & sects.), 39 e¢ 
seqq. 

Traut, J. J. H., quoted, 16, 62, 375 
et segg., 475, 477, 483, 486; re- 
ceives Wollaston Award for J. B. 
Harrison, xli. 

Tectonics of Davos district, 399-410 
figs. & pls. xxvi-xxvii(map & sects.) ; 
of Dolomites, see Torsion-structure, 

Teluet (S. Morocco), sect. to Tezert, 
200. 

Terebratulina gracilis-zone, features 
of Micraster in, 512-5138. 

Tertiary sea-bottom in S. Morocco, 
194-195 ; T. strike superposed upon 
Triassic do. in 8. Tyrol, 590. 

Test of Mécraster, evol. of sp. features, 
499-514; method of measurem. of, 
514-516 ; contrast betw. high-zonal 
& low-zonal chars., 515-517. 

Tezert (S. Morocco), sects. to Anti- 
Atlas, 200. 

Thames Valley Drift, Paleolith. im- 
plemts. from, xcii. 

Theodiscus hastatus, sp. nov., 53 & 
pl. ix. 

‘ Theory of the Earth,’ Hutton’s, vol. iii 
of, x—xi, lxxxix. 

Third Grit (Lr. Carb.) of Congleton 
Edge, 548, 552, 554, 555. 

Tuompson, B., on Geol. of Gr. Central 
Ry.: Rugby to Catesby, 65-87 figs. 
& list of foss. 

Tuomson, JoserH [the late], on Geol. 
of 8. Morocco & Atlas Mts., 190- 
212 w. sects. 

Thorness Bay (I. of Wight), <Amia 
from, 7 


Vol. 55.] 


Thorpe Fell (Yorks), limest.-knolls & 
shale of, 359, 360. 

Three Crowns (Spitsbergen), 682, 688. 

Throgmorton Street (London), Palzo- 
lith. implemts. from, xcil. 

Thrust-planes indic. by Craven Faults, 
351-353 ; thrust - planes, post- 
Cambr., in Glenelg, 374. 

TippemaNn, R. H., exhib. specims., 
Ixxxvili; quoted, 327, 328 ez segq. 

Tideswell Dale (Derby), sill & faulted 
inlier in, 239-250 figs. & pls. xix- 
xx (map & microse. sects.). 

Tiers-Duron torsion-system (S. Tyrol), 
626-627. 

Tipperary County, pseudo-foss. fr. 
Silur. of, ii. 

Tissington cutting (Derby), 226-229 
& pls. xvli—xviii (sects.) ; sponge-spi- 
cules in Carb. Limest. of, 716-717. 

Titula (Atlas Mts.), evid. of glacial 
action, 202. 

Tizi Likumpt (Atlas Mts.), sect. to 
Taghnowt, 204. 

Toadstone, definition of term, 238; 
see also Dolerite, Lavas. 

Todtalp (Davos district), serpentine 
of, 392, 407. 

Tonbridge (Kent), Hemiomus major, 
gen. & sp. nov. from, 413-415 figs. 

Torsion-structure of Dolomites, 560- 
634 figs. & pl. xl (map). 

Torsional eruptivity in Alpine areas, 
628. 

Totaigite, chem. anal. of, 373. 

Tourmaline, see Schorl-rock Pebbles. 

Trachytes in Atlas Mts., 209, 

Tramore (Waterford), Lr. Palzeoz. of, 
726-733 w. sects. & lists of foss. 

Tramore Limestone Series, 740, 742; 
correl. w. Orthoceras-limest. etc. of 
Seandinavia & Esthonia, 767-769. 

Tramore Slates, 740, 742. 

Tramoria punctata, gen. & sp. nov., 
758-760 & pl. xlix. 

Trappoid breccia, Upper Perm. age 
of, 102, 103. 

Tremadoe age of basal Protozoic in 
Central Anglesey denied, 643. 

Triactiscus lanceola, sp. nov., 53 & 
pl. ix. 

Trias, relat. of Upper Perm. to, in Lr. 
Severn Basin, 102; Tr. of Stourton, 
monotreme (?) footpr. from, lxxxix ; 
Tr. sandst. of Chase End Hill, 149; 
Tr. of Davos district, 385-389 ; 
Tr. success. in 8. Tyrol, 560-562. 

Trilonche, gen. nov., 47. 

elegans, sp. nov., 48 & pl. viii. 

—— Pittmani, sp. nov., 48 & pl. viii. 

— vetusta, sp.nov. & var. a, 48 & 
pl. viii. 


GENERAL INDEX. 


791 


Trinidad (W.I.), Oceanic deposits of, 
177-189 w. map, vert. sects. & chem, 
anal, 

Trinucleus hibernicus, '744-745. 

Trochodiscus (?) dubius, sp. nov., 218 
& pl. xvi. 

planatus, sp. nov., 53 & pl. ix. 

Trust Funds, statement of, xxxvi- 
XXXVIi. 

Trwyn Pen-careg (Anglesey), crush- 
conglom. of, 659-660. 

Trwyn y Pare (Anglesey), foldg. of 
rocks at, 652, 664. 

Tuckhill (Shropshire), Middle Perm. 
of, 103 & table. 

Tufa, calcareous, in S. Morocco, 195, 
196. 

Tufaceous rhyolites of Bodlondeb, 
173; do. of Waikino & Waihi, 
458, 459; tuf. limest. above thick 
ash, betw. Ashbourne & Crake Low, 
225 et segg., 235-236; limest. of 
Congleton Edge, 551, 557-558. 

Tuffs in radiolar. series of N.S.W., 
20 et segg., 34, 42; felsitic, nr. Con- 
way, 170-176 w. map & sect.; thin, 
tuffs in Carb. rocks betw. Ashbourne 
& Crake Low, 225 et segq., 235-236 ; 
tuff in Tideswell Dale, 245, 248 & 
pl. xx (microse. sect.); & agglom. 
in Carb. Limest. Series of Congleton 
Edge, 548-559 w. map & sects.; 
Ordov. of Waterford coast, 725 et 
seqg., 765-766. 

Turdus merula (?) fr. Ightham fissure, 
420 


Tyrone & Londonderry granites, age 
of, 273-275 figs. 


Unconformity, proof of, in N. Angle- 
sey, 648-650. 

Underground waters, varying com- 
posit. of, lxxiv. 

Upper Scar Limestone, correl. of, 350, 
362. 

Urika, Wad (Atlas Mts.), geol. of, 
206 w. sect. 


Val di Mezzodi, see Pissadoi Ravine. 

Val la Stries (S. Tyrol), structur, 
significance of, 591. 

Vallbach (S. Tyrol.), fault-dykes & 
sills, 569-571. 

Valparola-Hisenofen Fault (S. Tyrol), 
621. 

Valuation of property of Geol. Soc., 
XXXVI111. 

Van pen Broeck, E., elected For, 
Memb., xcii. 

Varda (S. Tyrol), tectonics of, 585. 

Variolites of Davos district, 398. 

Variolitic serpentine of Anglesey, 


792 


281-284 figs. 285-289 & pl. xxiii 
(microse. sects.), 803-304. 

Verrucano of Davos district, 389-390, 
399, 401, 410, 411. 

Vertebrata fr. Ightham rock-fissure, 
419-429 & pl. xxviii. 

Vesicular lavas in Tideswell Dale, 240 

_ et segg., 247 & pl. xx (microse. sects.). 

Vespertilio Bechsteint (?) fr. Ightham 
fissure, 420. 

Daubentoni (?) do. do., 420. 

murinus, see V. Bechsteini. 

Virgation of fault-lines (Groden Pass 
anticline), 576-577. 

Virgloria-kalk of Davos district, 389. 

Volcanic rocks, Ordov. contemporan., 
of Waterford coast, petrology of, 
763-766 w. chem. anal. 


Wad Demnat, etc., see Demnat, etc. 

Waihi (N.Z.), rhyolites of, 458-460, 
461-462, 463-464 & pls. xxxiii— 
xxxiv (microsc. sects.) ; chem. anal. 
of same, 467. 

Waikino (N.Z.), rhyolites of, 450, 
457-458, 460-461 & pls. xxxii- 
xxxiv (microse. sects.). 

Waitekauri (N.Z.), andesites of, 464- 
465. 

Watcort, C. D., elected For. Memb., 


re 

Waldhalle (Rigen), see Kollickerbach. 

Watrorp, E. A., on -Ironst. Foss. 
Nodules of the Lias [tide only], xcii. 

Watturr, T. H., exhib. schorl-rock 
pebbles, viii. 

Warp, J., Lyell Fund Award to, 
xl viii. 

Warley district (Staffs), Middle Perm. 
of, 115; Perm. breccias of, 117. 
Warren, 8. H., exhib. specims., xcii. 
Warshill (Shropshire), Perm. of, 110- 

111 & pl. xi (map). 

Washbrook cutting (Derby), 226. 
Waters, subterranean, varying com- 
posit. of, lxxiv. ‘ 
Water-supply, geol. considerations 
conn. with, lxix-lxxiv ; contamina- 

tion of, Ixxvii. 

Waterford Co. (Ireland), Lr. Palzoz. 
bedded rocks of, 718-772 figs. & 
pl. xlix (foss.). 

Warts, W. W., on Microse. Study of 
Rocks of N. Anglesey, 675-678 ; 
quoted, 585, 633, 666. 

Wealden Beds of Tonbridge, Hemi- 
omus major, gen. & sp. nov. from, 
413-415 figs.; of Ansty Lane, bird (?) 
from, 416-418 figs. 

Wells, geol. considerations conn. with, 
lxxi-lxxiv. 


GENERAL INDEX. 


[Nov. 1899. 


Wengen Series of 8. Tyrol, 561, 562, 
569, 571 et seqg. 

Wenlock Limestone-pebbles in Middle 
Perm. conglom., 120-121 & tables 
ii-iv; W. L. of Malvern district, 
Huthemon igerna, gen, & sp. nov. 
from, 696-699 figs. 

ee strata of 8. Tyrol, 560, 584, 
585. 

Wuirtaker, W., addresses to Medal- 
lists & recipients of Funds, xxxix et 
segg.; obituaries of deceased Fel- 
lows, etc., liii-lxvili; on some Prac- 
tical Applic. of Geol., lxix—lxxxiili. 

White-leaved Oak district (Malverns), 
geol. struct. of, 157-160; map & 
sects., 134, 135, 136. 

Wiesen-Amselfluh fold (Davos), 401 & 
pl. xxvii (sect.). 

Wight, I. of, Amia fr. Oligoe. of, 
1-10 & pli. 

Wison, E., obituary of, lxvi. 

Wind-action, polishg. pebbles, i, xc— 
xci. 

Winter Combe (Raggedstone Hill), 
sect. descr. & fig., 145-147. 

Winterburn Reservoir (Yorks), folded 
& brecciated limest. of, 340 fig., 347- 
348 fig. 

Wissowerbach (Rigen), composit. of 
Drift-sand, 313; Drift & Chalk at, 
319. 

Wolkenstein Fault (8. Tyrol), 570. 

Wo.taston Medallists, list of, xxvii. 

Woutaston Fund, list of recipients, 
XXVIil. 

Wombwell’s Farm (Chilton), glaucon. 
limest. fr. Kim. Clay of, lxxxvii. 
Woon, J. G., on Foss. Oak fr. Chep- 

stow, lv. 

Woop, Miss E. M. R., quoted, 567, 
675. 

Woopwarp, A. Smiru, quoted, 89. 

Woolhope Limestone-pebbles in Mid- 
dle Perm. conglom., 120 & tables 
ill-iv. 

Wouldham (Kent), Hippurites from, 
XC. 


Xiphosphera minax, sp. nov., 45 & 
pl. viii. 


Yoredale rocks betw. Ashbourne & 
Crake Low, 224 ez segg. © 


Zanclodon cambrensis, sp. nov., 89-96 
& pl. x. 

Zarktan (Atlas Mts.), 202. 

ZEILLER, R., elected For. Corr., Ixxxvii. 

Zoisite in Anglesey rocks, 296. 

Zonal collecting, advantages of, 497. 


PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET, 


PROCEEDINGS 


OF THE 


GEOLOGICAL SOCIETY OF LONDON. 


SESSION 1898-99. 


November 9th, 1898. 
W. Warraker, B.A., F.R.S., President, in the Chair. 


Richard Taylor Manson, Esq., Derneholm, Stanhope Road, 
Darlington, was elected a Fellow of the Society. 


The List of Donations to the Library was read. 


The PresIDENT invited the attention of the Fellows to the new 
Geological Survey Index Map of England and Wales, which had 
been hung upon the walls of the meeting-room during the recess. 


Mr. Baverman, in exhibiting a map of the Gellivaara iron-ore 
deposits, pointed out that these constitute a chain some 5 miles 
in length, and are made up essentially of magnetite interlaminated 
with apatite. In addition to these mines, which are far north 
of the Arctic Circle (70 miles north and 120 miles west of the Gulf 
of Bothnia), he had had an opportunity of visiting the deposits of 
Kiirunavaara, 100 miles still farther north; here the rocks are of 
a slaty character, and the magnetite is included in felsite-porphyry. 
The Gellivaara ores are contemporaneous with the surrounding rock, 
while the Kiirunavaara ores appear to have been introduced at a 
later period. Mr. Bauerman exhibited specimens from both 
districts, and drew attention to the phenomena of polishing by 
wind-action, etc. 


The following communications were read :— 


1. ‘On the Paleozoic Radiolarian Rocks of New South Wales.’ 
By Prof. T’. W. Edgeworth David, B.A., F.G.8., and E, F. Pittman, 
Esq., Assoc.R.S.M., Government Geologist, New South Wales, 

VOL. Ly. a 


il PROCEEDINGS OF THE GEOLOGICAL socreTy. [Feb. 1899, 


2. ‘On the Radiolaria in the Devonian Rocks of New South 
Wales.’ By G. J. Hinde, Ph.D., F.R.S., F.G.S. 


In addition to the map and specimens mentioned on p.i, the 
following were exhibited :— 


Rock-specimens of Radiolarian Limestones, Claystones, and Tuffs 
(Devonian) from New South Wales, with Microscope-sections of the 
same, and four Photographs showing Radiolarian Rocks 2m situ, 
exhibited by Dr. G. J. Hinde, F.R.S., F.G.S., in illustration of 
the papers on that subject. 


November 23rd, 1898. 
W. Wairaxer, B.A., F.R.S., President, in the Chair. 


John Solomon Vivian Bickford, Esq., Basset Road, Camborne; 
and Louis HE. Stevenson, Esq., Temple Sowerby, Penrith, were 
elected Fellows; and C. D. Walcott, Esq., Director of the United 
States Geological Survey, Washington (D.C.), was elected a Foreign 
Member of the Society. 


The List of Donations to the Library was read. 


It was announced that the President and Camel would be 
At Home to the Fellows on the evening of Friday, December 
16th, 1898. a 


Sir A. Gerxre drew attention to some specimens on the table, 
which had been collected by the officers of the Geological Survey 
from the Silurian rocks of County Tipperary. These contained 
impressions that bore a close resemblance to flattened and drawn-out 
graptolites, and others that might be taken for mollusca or phyllo- 
poda enlarged by cleavage. It seemed to him, however, extremely 
doubtful whether these forms were truly of organic origin. They 
were exhibited in the hope that the paleontologists in the Society 
might be able to throw some light upon them from the zoological 
side. 


Dr. G. J. Hrypz exhibited and commented on specimens of 
Devonian rocks sent by Prof. Edgeworth David and Mr. Pittman 
from the railway-section at Tamworth (New South Wales), which had 
been received since their paper was read. ‘The specimens included 
radiolarian shales and submarine tuffs containing impressions of 
Lepidodendron australe; similar shales with bands of tuff regularly 


Vol. 55. ] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. lil 


interstratified ; radiolarian chert irregularly broken up, and inter- 
mingled with tuff; and hard shale, with numerous radiolaria 
weathered out on the surface. Microscopic sections prepared from 
these rocks were also exhibited. 


The following communications were read :— 


1. ‘ Note on a Conglomerate near Melmerby (Cumberland).’ By 
J. E. Marr, Esq., M.A., F.R.S., F.G.S. 


2. ‘Geology of the Great Central Railway (New Extension to 
London of the Manchester, Sheffield & Lincolnshire Railway) : 
Rugby to Catesby.’ By Beeby Thompson, Hsq., F.G.S., F.C.S. 


3. ‘On the Remains of Amza from Oligocene Strata in the Isle 
of Wight.’ By E. T. Newton, Esq., F.R.S., F.G.S. 


The following specimens and maps, in addition to those men- 
tioned on p. ii, were exhibited :— 


Specimens exhibited by J. E. Marr, Esq., M.A., F.R.S., F.G.S., 
in illustration of his paper. 

Fossils exhibited by Beeby Thompson, Esq., F.G.S., F.C.S., in 
illustration of his paper. 

Specimens of Amia from Oligocene Beds in the Isle of Wight, 
exhibited by G. W. Colenutt, Esq., F.G.S.; and others exhibited by 
the Director-General of H.M. Geological Survey, in illustration of 
Mr. EK. T. Newton’s paper. 

New Geological Survey 1-inch Maps: Sheet 100, Isle of Man 
(Solid and Drift), and new ed. Sheets 355 & 356, Start Point, etc. 
(Drift), presented by the Director-General of that Survey. 


December 7th, 1898. 
W. Warrarer, B.A., F.R.S., President, in the Chair. 


Louis J. Abrahams, Esq., 16 Upper Hamilton Terrace, Maida Vale, 
N.W.; William Bruce Bannerman, Esq., F.S.A.Scot., The Lindens, 
Sydenham Road, Croydon; Torrington Blatchford, Esq., B.A., 
Geological Survey Office, Perth (Western Australia); Ananda K. 
Coomdra-Swamy, Esq., Walden, Worplesdon (Surrey) ; Dahyabhai 
Pitamherdas Derasari, Esq., M.R.A.S., Ahmedabad, Bombay Presi- 
dency (India); Frederic Walter Hodson, Esq., Assoc.M.Inst.C.E., 
Bank Chambers, Loughborough; Joseph Husband, Esq., Assoc. 
M.Inst.C.E., 66 Mona Road, Spring Vale, Sheffield; Prof. John 
Joly, D.Sc, F.R.S., 12 Northbrook Road, Dublin; Frederick 
William Justen, Esq., 120 Alexandra Road, Hampstead, N.W.; 
Thomas Newbitt, Esq., 17 Royal Crescent, West Cliff, Whitby ; 


iv PROCEEDINGS OF THE GHOLOGICAL socreTy. [Feb. 1899, 


Richard Stevenson Norman, Esq., 17 Cowley Hill Lane, St. Helen’s 
(Lancashire); Edward John Power, Esq., 8 Gledhow Gardens, 
S.W.; Prof. H. Narayana Rau, M.A., 11 Sydoji Street, Triplicane, 
Madras; Henry John Rofe, Esq., M.A., 8 Victoria Street, S.W.; 
Ernest Willington Skeats, Esq., B.Sc. (Lond.), Assoc. R.C.S., 
17 Elthiron Road, Walham Green, 8.W.; George Thomas, Esq., 
32 Stuart Street, Aberdare; Charles Wardingley, Esq., 1 Durnlea, 
Littleborough, near Manchester; Mr. Willem van Waterschoot 
van der Gracht, 280 Heerengracht, Amsterdam (Holland); and 
Harold George Watson, Esq., The Beeches, Aldridge, were elected 
Fellows of the Society. 


The List of Donations to the Library was read. 


Mr. J. G. Woop commented on a specimen of sound oak, which 
he exhibited and proposed to present to the Society. The oak was 
found in sinking the cylinders of Chepstow Bridge (Great Western | 
Railway) over the River Wye, under about 40 feet of blue clay, 
sand, etc., and 15 feet below low-water mark. 


The following communications were read :— 


1. ‘The Geological] Structure of the Southern Malverns and of 
the adjacent District to the West.’ By Prof. T. T. Groom, M.A., 
D.Sce., F.G.S8. 

2. «The Permian Conglomerates of the Lower Severn Basin.’ 
By W. Wickham King, Esq., F.G.S8. 


In addition to the specimen mentioned above, the following were 
exhibited :-— 

Specimens exhibited by Prof. T. T. Groom, M.A., D.Sec., F.GS., 
in illustration of his paper. 

Fossils and Rock-specimens exhibited by W. Wickham King, Esq., 
F.G.S., in illustration of his paper. 

Sheets 73, 86, 89, 107, and 150 of the Map of the Geological 
Survey of Saxony, presented by the Director of that Survey. 


December 21st, 1898. 
W. Warrarer, B.A., F.R.S., President, in the Chair. 


William George Crawford Hughes, Esq., Assoc.M.Inst.C.E., 
Haslemere, Brincliffe, Sheffield; Walter Maxwell, Ph.D., Honolulu 
(Hawaii); A. C. Pilkington, Esq., B.A., The Hazels, Prescot (Lanca- 
shire); and H. H. Thomas, Esq., B.A., Roxborough Park, Harrow, 
were elected Fellows of the Society. 


Vol. 55.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. Vv 
The List of Donations to the Library was read. 


The PrestipENt announced that Mr. F. W. Harmer, F.G.8., had 
most generously offered to the Society the manuscript maps of 
the Drift of the Eastern Counties made by the late Mr. Searles 
Wood, Jr., and by himself. The Council, in accepting the maps, had 
passed a resolution specially thanking Mr. Harmer for the gift, and 
the Fellows were now asked to add their thanks to those of the 
Council. 


The following communications were read :— 


1. ‘On a Megalosauroid Jaw from Rhetic Beds near Bridgend 
(Glamorganshire).’ By E. T. Newton, Ksq., F.R.S., F.G.8. (Com- 
municated by permission of the Director-General of H.M. Geological 
Survey.) 

2. ‘The Torsion-Structure of the Dolomites. By Maria M. 
Ogilvie, D.Sc. [Mrs. Gordon]. (Communicated by Prof. W. W. 
Watts, M.A., Sec.G.S.) 


The following specimens were exhibited :— 


Megalosauroid Jaw from the Rheetic Beds near Bridgend, exhibited 
by the Director-General of H.M. Geological Survey. 

Casts of the same Jaw, exhibited by E. T. Newton, Esq., F.R.S., 
F.G.8., in illustration of his paper. 

Rock-specimens, Microscope-sections, and Photographs exhibited 
by Prof. W. W. Watts, M.A., Sec.G.S., in illustration of Miss Ogilvie’s 
[ Mrs. Gordon’s] paper. 


January 4th, 1899. 
W. Wuaitaxer, B.A., F.R.S., President, in the Chair. 


James Vincent Elsden, Esq., B.Sc., Storrington, Pulborough 
(Sussex); James Alexander Leo Henderson, Ph.D., 1 Kingswood 
Road, Upper Norwood, 8.E.; and Harry Bertram Nichols, Esq., 
Assoc.M.Inst.C.E., Grosvenor Chambers, 59 Corporation Street, 
Birmingham, were elected Fellows of the Society; Prof. Marcel 
Bertrand, Paris; and Prof. A. Milne-Edwards, Paris, were elected 
Foreign Members; and Prof. Th. Liebisch, Gottingen, was elected a 
Foreign Correspondent of the Society. 


The following Fellows, nominated by the Council, were elected 
Auditors of the Society’s Accounts for the preceding year :— 
H. Baverman, Esq., and Dr. G. J. Hinpz, F.R.S. 


The List of Donations to the Library was read. 


V1 PROCEEDINGS OF THE GEOLOGICAL society. [Feb. 1899 


Capt. A. W. Srirre, in exhibiting a fossil Cardiwm (?) from the 
beach at the foot of the cliffs of Ormara (Makran Coast), made the 
following remarks :—The specimen on the table has been kindly 
lent to me by Mr. Ffinch, Director of the Government Indo- 
Kuropean Telegraphs. The peninsula of Ormara, whence the shell 
comes, is composed of a mass of flat-topped hills about 10 miles in 
length; it is about 1200 feet high at its western end, sloping down 
to about 400 feet at its eastern end—flat on the top, and ending on 
all sides in cliffs. The rocks are chiefly clay, with a thin conformable 
capping of shelly breccia 20 to 50 feet thick. The fossils in the clay 
are difficult to find, and probably are generally enclosed in nodules 
of the clay somewhat altered, as in this specimen. The fossil now 
exhibited was picked up on the sandy beach near the foot of the cliffs, 
which are naturally undergoing rapid denudation. The formation 
was considered to be of Miocene age, according to a paper read by 
me before this Society in 1874, as determined by Mr. Etheridge. 
I should be glad to learn whether this fossil supports that view of the 
age. Nearly all the coast in question for many hundreds of miles 
is of similar formation: the strata are as a rule slightly inclined 
only, and of fantastic outline. 


The following communications were read :— 


1. ‘Geology of the Ashbourne & Buxton Branch of the London 
& North-Western Railway.—Ashbourne to Crakelow. By H. H. 
Arnold-Bemrose, Esq., M.A., F.G.S. 


2. ‘The Oceanic Deposits of Trinidad (W.I.).’ By Prof. J. B. 


Harrison, M.A., F.G.8S., and A. J. Jukes-Browne, Hsq., B.A., 


In addition to the specimen described above, the following 
were exhibited :— 

Rock-specimens, Microscope-sections, Lantern-slides, and Photo- 
graphs, exhibited by H. H. Arnold-Bemrose, Esq., M.A., F.G.S., 
in illustration of his paper. 

Rock-specimens exhibited by Prof. J. B. Harrison, M.A., F.G.S., 
and A. J. Jukes-Browne, Esq., B.A., F.G.S., in illustration of their 
paper. 


January 18th, 1899. 
W. Warrtaxrer, B.A., F.R.S., President, in the Chair. 
Edmund Dunlop Puzey, Esq., B.A., B.E., Secunderabad, Deccan 
(India); and Charles Bertie Wedd, Esq., B.A., Geological Survey, 
28 Jermyn Street, S.W., were elected Fellows of the Society. 


The List of Donations to the Library was read. 


Wolk 5 5.1 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. vil 


The following communications were read :— 


1. ‘On a small Section of Felsitic Lavas and Tuffs near Conway 
(Caernarvonshire).’ By Frank Rutley, Esq., F.G.S. 


2. ‘The Geology of Southern Morocco and the Atlas Mountains.’ 
By the late Joseph Thomson, Esq. (Communicated by the 
President. ) 


The following specimens, prints, and maps were exhibited :— 


Rock-specimens and Microscope-sections, exhibited by Frank 
Rutley, Esq., F.G.S., in illustration of his paper. 

Prints of Photogravure Plates for the Geological Survey Memoir 
on the ‘ Geology of the Isle of Purbeck & Weymouth,’ prepared and 
exhibited by A. Strahan, Esq., M.A., F.G.S. . 

Geological Survey of England and Wales: 1-inch Geological Map, 


new series, Sheet 300 (Drift) Alresford, by C. EK. Hawkins, etc., 
1898, presented by the Director-General of H.M. Geological Survey. 


Carte Géologique Internationale de l’Europe, , a5 so? Lart. 3, 
Sheets A iii, Aiv, Bi, Biv, Cv, D v, D vi, 1898, presented by the 
Commissioners. 


Harta Geologica generala a Romaniei: Sheets 44 to 47, 1898, 
presented by the Director of the Rumanian Geological Survey. 


February Ist, 1899. 


W. Warraxer, B.A., F.R.S., President ; and afterwards 
Prof. T. G. Bonney, D.Sc., F.R.S., Vice-President, in the Chair. 


Brandon Talfourd Brierley, Esq., Assoc.M.Inst.C.E., Bellayre, 
Lymm (Cheshire), was elected a Fellow of the Society. 


The List of Donations to the Library was read. 


The following communications were read :— 


1. ‘On Radiolaria in Chert from Chypon’s Farm, Mullion 
Parish (Cornwall).’ By Dr. G. J. Hinde, F.R.S., F.G.S. 


2. ‘Gravel at Moreton-in-the-Marsh (Gloucestershire).’ By 
S. S. Buckman, Esq., F.G.S. 

3. ‘On the Occurrence of Pebbles of Schorl-Rock from the 
South-west of England in the Drift-deposits of Southern and 
Eastern England.’ By A. E. Salter, Esq., B.Sc., F.G.S. 

VOL. LY. | 6 


Vill PROCEEDINGS OF THE GEOLOGICAL socieTy.  [May, 1899. 


The following specimens were exhibited :— 


Specimens and Microscope-sections of Radiolarian Chert from 
Chypon’s Farm, Mullion Parish, exhibited by Dr. G. J. Hinde, F.R.S., 
F.G.S8., in illustration of his paper. 


_ Specimens of Gravel from Moreton-in-the-Marsh, exhibited by 
8. 8. Buckman, Esq., F.G.S., in illustration of his paper. 


Specimens and Microscope-sections of Schorl-rock Pebbles from 
the South-west of England, found in the Drift of Southern and 
Eastern England, exhibited by A. E. Salter, Esq., B.Sc., F.G.S., in 
illustration of his paper. 


Specimens and Microscope-sections of Pebbles from Drift con- 
taining Schorl, exhibited by C. A. Matley, Esq., F.G.8., on his 
own behalf, and on that of T. H. Waller, Esq. 


ANNUAL GENERAL MEETING, 


February 17th, 1899. 


W. Wairaxer, B.A., F.R.S., President, in the Chair. 


ReEporRT OF THE CounciIL FoR 1898. 


Once again the Council are in a position to state that the upward 

tendency in the number of Fellows and the financial prosperity of 

the Society, which have formed matter for congratulation in recent 

Annual Reports, have continued uninterruptedly during the past 
ear. 

In 1898 the number of Fellows elected into the Society was 52, 
of whom 41 paid their Admission Fees before the end of the year. 
Moreover, 17 Fellows who had been elected in 1897 paid their 
Admission Fees during the last twelve months, the total accession 
of new Fellows during the year under review amounting, therefore, 
to 58. 

On the other hand, there was a total loss of 54 Fellows during the 
past year—28 by death, 16 by resignation, 2 by transference to the 
List of Foreign Members, and 8 by removal from the List because 
of non-payment of their Annual Contributions. 

From the foregoing figures it will be seen that the actual 
increase in the number of Fellows is 4. 

Of the 28 deceased Fellows, 8 had compounded for their Annual 
Contributions, 18 were Contributing Fellows, and 2 were Non- 
Contributing Fellows. On the other hand, 3 Fellows during the 
past year became Compounders. 

The total accession of Contributing Fellows is thus seen to be 
55 (58—3), and the total loss being 42 (184+16+8), the increase 
in the number of Contributing Fellows is 13, as compared with an 
increase of 18 in 1897. 

Turning now to the Lists of Foreign Members and Foreign 
Correspondents, it will be remembered that at the end of 1897 
there was 1 vacancy in the List of Foreign Members and 2 in the 

b2 


x PROCEEDINGS OF THE GEOLOGICAL society. [May 1899, 


List of Foreign Correspondents. During the year 1898 the Society 
had to lament the loss by death of 5 of its Foreign Members and 
1 Foreign Correspondent. The vacancies thus created were in 
part filled by the election of 3 Foreign Members and 3 Foreign 
Correspondents, but at the end of the year there were still 3 vacancies 
in the List of Foreign Members, and 1 in the List of Foreign 
Correspondents. 

The total number of Fellows, Foreign Members, and Foreign 
Correspondents, which stood at 1333 on December 31st, 1897, 
had increased to 1336 by the end of 1898. 

Proceeding now to consider the Income and Expenditure of the 
Society during the twelve months under review, the figures, set 
forth in detail in the accompanying Balance-sheet, may be 
summarized as follows :— 

The total Receipts, including the Balance of £723 3s. Od. 
_ brought forward from. the previous year, amounted to £3575 7s. 1d., 
being £102 10s. 1d. more than the estimated Income for the year. 
On the other hand, the total Expenditure during 1898 amounted 
to £2499 6s. 5d., being £175 17s. 7d. less than the estimated 
Expenditure for that year. The Balance remaining available for 
the current year is £1076 Os. 8d. 

Among the Receipts during 1898 will be noticed a sum of 
£15 18s. 2d. for ‘Interest on Deposit.’ It may be explained 
here that on January 19th, 1898, the Treasurer was authorized by 
the Council to place £1000, of the then available Balance, on 
Deposit at the Bankers; and it was found possible to avoid making 
any withdrawal from that deposit until very nearly the close of 
the year. 


The Extraordinary Expenditure, which would have been incurred. 


in carrying out the Redecoration of the Society’s Apartments, was 
necessarily postponed, in view of the declared intention, on the part 
of H.M. Office of Works, to lay down a new system of drainage in 
connexion with the Society’s Apartments. This work is to be 
commenced almost immediately, and the Council, having seized the 
opportunity of pointing out to the Secretary of H.M. Office of 
Works the need for improved lavatory accommodation, the Depart- 
ment has agreed to carry out the work; but, on the ground that 
the proposed new arrangements involve a structural alteration and 
addition to the building, has asked the Society to contribute the 
sum of £200 towards the cost. This is a contribution which the 
Council feel justified in recommending, and the assent thereto of the 
Fellows is hereby requested. 

The MS. of the Third Volume of Hutton’s ‘ Theory of the Earth,’ 
edited by Sir Archibald Geikie, under the circumstances detailed in 
last year’s Report, is now in the press. A circular letter was 
recently sent to all Fellows, Foreign Members, and Foreign Cor- 
respondents of the Society, and to all Institutions which receive 
the Society’s publications, inviting them to state whether they 
wished to purchase one or more copies of the volume in question, 
on payment of Two Shillings per copy in the case of Fellows, and 


Le ee ae — 


a 


Vol. 55.] ANNUAL REPORT. x1 


Three Shillings and Sixpence per copy in the case of non-Fellows. 
The number of replies received is hardly such as to warrant the 
printing of more than 500 copies, and it is expected that the sum 
of £50 set down in the Estimates for the current year will amply 
cover the cost of publication of the Hutton Manuscript. 

The Council have pleasure in announcing the completion of 
Vol. LIV of the Society’s Quarterly Journal, and the commence- 
ment of Vol. LV. During the past year Index Slips have been 
issued with each number of the Journal, in accordance with the 
plan elaborated by the Geological Sub-Committee of the Inter- 
national Catalogue Committee. ‘These Index Slips are so prepared 
as to furnish the materials for a card-catalogue of authors and 
subjects, and it is proposed to continue the issue of such slips with 
the Journal of the current year. 

The Record of Geological Literature added to the Society’s 
Library during 1898 will be brought up to the closing day of that 
year. Itis hoped to issue it this year, and in future years, con- 
currently with the May number of the Quarterly Journal. The 
labour involved in preparing and arranging the MS. for the printers, 
and in passing it through the press, is very great; and it has beea 
found impossible to devote an adequate amount of attention to the 
work and its revision, in the short space of time which separates the 
end of December from the beginning of February. 

Dissatisfaction having been expressed with the method, hitherto 
in force, of selecting papers for publication in the Society’s Quarterly 
Journal, the Council appointed a Committee to consider the whole 
question. 

The Committee made the following recommendations, which were 
adopted by the Council in April last, and have since that time 
been acted on :— 

‘1. That it be a recommendation to the President or Chairman 
of the Council, when acting under Bye-Laws, Sect. XXI, Art. 6, 
to appoint as Referees a sufficient number of Fellows, including 
the President and Secretaries, to form a body which the Council 
may appoint as a Committee of Reference, to examine the paper 
and report thereon. The Committee shall be at liberty to take the 
opinion of any person or persons having special knowledge of the 
subject dealt with in the paper, and such opinions may be embodied 
in their Report. 

‘2, That in future all papers be referred, as soon as convenient, 
after they have been delivered at the House of the Society.’ 

It was felt by the Committee that, as any change would be in 
the nature of an experiment, it was undesirable to make any 
alteration in the Bye-Laws, at present, if it could be avoided. It 
will be seen, therefore, that the above resolutions are framed in 
such a manner that, while they are in strict accordance with the 
Bye-Laws, they yet effect a very considerable change in the method 
of reference of papers, which has been in existence for many years 
past. 


Xil PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


The experiment has, so far, worked well, and the Council hope 
that it will give satisfaction both to the Fellows, and to Authors 
of papers. 

The following Awards of Medals and Funds have been made by 
the Council :— 

The Wollaston Medal is awarded to Prof. Charles Lapworth, 
LL.D., F.R.S., in recognition of the value of his researches con- 
cerning the mineral structure of the earth, and more particularly of 
his work among the older rocks of the Highlands of Scotland and 
the Midland Counties of England, and the Graptolitic rocks of 
Scotland. 

The Murchison Medal, with a sum of Ten Guineas, is awarded to 
Mr. B. N. Peach, F.R.S.; and a second Murchison Medal, with a 
further sum of Ten Guineas, to Mr. John Horne, F.R.S.E., in 
recognition of the value of their joint work in unravelling the 
intricate geological problems of the North-western Highlands of 
Scotland. 

The Lyell Medal, with a sum of Twenty-Five Pounds, is awarded 
to Lieut.-Gen. C. A. McMahon, F.R.S., in recognition of the value 
of his services to Petrology, and more particularly of the work done 
by him in India. 

The Bigsby Medal is awarded to Prof. T. W. Edgeworth David, 
as an acknowledgement of his eminent services to Geology in 
investigating the rocks of New South Wales, and in connexion with 
the coral-reef boring in the Island of Funafuti. 

The Balance of the Proceeds of the Wollaston Donation Fund is 
awarded to Prof. J. B. Harrison, M.A., in recognition of his geo- 
logical work in the West Indian Islands, and to encourage him in 
turther research. 

The Balance of the Proceeds of the Murchison Fund (supple- 
mented by a sum of £3 13s. 8d. from the Barlow-Jameson Fund) is 
awarded to Mr. James Bennie, in recognition of his work in adding 
to our knowledge of the Palzeozoology and Paleobotany of the 
Carboniferous and Old Red deposits of Scotland, and to assist him in 
further researches. 

A moiety of the Balance of the Proceeds of the Lyell Geological 
Fund is awarded to Mr. Frederick Chapman, as an acknowledgement 
of the value of his work in investigating the Foraminifera and other 
micro-organisms of various deposits, and to encourage him in 
further work. 

The other moiety of the Balance of the Proceeds of the Lyell 
Geological Fund is awarded to Mr. John Ward, in recognition of 
his valuable contributions to our knowledge of the Paleontology of 
the Carboniferous and other rocks of Staffordshire, and to encourage 
him in further work. 


Vol. 55-| ANNUAL REPORT. Xili 


Report oF THE LIBRARY AND Museum Commitrex For 1898. 


Your Committee have pleasure in stating that the Additions made 
to the Society’s Library during the past year were superior in 
number, and assuredly not inferior in interest, to the acquisitions 
recorded in previous annual reports. 

Enumerating, in the first place, the Donations, it is found that the 
Library received during 1898 no less than 113 Volumes of separately 
published Works; 517 Pamphlets and detached Parts of Works; 
174 Volumes and 95 detached Parts of Serial Publications (Transac- 
tions, Memoirs, Proceedings, etc.) ; and 17 Volumes of Newspapers. 
Moreover, 80 Sheets of Maps were presented by various Donors. 

Among the foreign maps may be mentioned Sheets 26 to 37 of 
the Geologic Atlas of the United States; 14 Sheets of Maps, with 
accompanying Descriptions, of the Geological Survey of Finland ; 
10 Sheets of the Italian Geological Survey Map (Calabria and the 
Apuan Alps); 4 Sheets, with Explanations, of the Hesse-Darmstadt 
Geological Survey Map; and 5 Sheets of Maps of the Saxon 
Geological Survey. 

From our own country came 8 Sheets of the 1-inch Map of the 
Geological Survey of England and Wales; the Banchory (Kin- 
cardineshire) Sheet of the Geological Survey Map of Scotland; and 
Sir A. Geikie’s new Geological Map of England and Wales on the 
scale of 10 miles to the inch. 

Special attention may be directed to the highly-prized donation 
made to the Society’s Library by Mr. F. W. Harmer, consisting of 
the manuscript Maps of the Drift of the Eastern Counties of 
England, drawn up by the late Mr. Searles Wood, Jr., and by 
himself, 

Turning now from Maps to Books, it is felt that the thanks of 
the Society are due to Mrs. Topley for the gift of no less than 156 
Memoirs, Pamphlets, etc. from the Library of the late Mr. W. Topley ; 
and attention is directed to the following, among other donations: 
‘Elemente der Gesteinslehre, by H. Rosenbusch; ‘Manual of 
Determinative Mineralogy,’ by G. J. Brush & 8. L. Penfield ; 
‘Aids in Practical Geology,’ 3rd ed., by G. A. J. Cole; ‘ First 
Lessons in Modern Geology,’ by the late A. H. Green (edited by 
J. F. Blake); ‘ Geology for Beginners,’ by W. W. Watts; ‘ Principles 
of Stratigraphical Geology,’ by J. E. Marr; the Annual Reports of 
the Kansas, Maryland, and Canadian Geological Surveys; 14 
volumes of Memoirs of the Geological Surveys of Sweden, Spain, 
and other countries. 

The Maps and Books enumerated in the foregoing paragraphs 
were the gift of 216 Personal Donors, 92 Government Departments 
and other Public Bodies, and 155 Societies and KHditors of 
Periodicals. 

The Purchases made on the recommendation of the Committee 
comprised 40 Volumes and 16 detached Parts of separately published 
Works; 29 Volumes and 18 detached Parts of Serial Publications ; 
and 27 Sheets of Maps. 


XIV PROCEEDINGS OF THE GEOLOGICAL society. [May 1899, 


Among the Purchased Maps, attention may be directed to the 
Geological Survey Index Map of England and Wales, on the scale 
of 4 miles to the inch, which has been mounted on a roller and 
hung up in the Meeting-room, in lieu of the Greenough Map. 
The latter has been suitably framed, and is now displayed on the 
wall of the Entrance-hall to the Society’s Apartments. 

During the Recess the 260 Volumes of Tracts presented to the 
Society’s Library by Lady Prestwich, in fulfilment of the wishes of 
the late Sir Joseph Prestwich, were placed in two bookcases erected 
for that purpose on the floor of the Museum. ‘These publications 
will thus form a small library, complete in itself, and henceforth 
distinguished as ‘The Prestwich Bequest.’ 

The total Expenditure incurred in connexion with the Library 
during the past twelve months was as follows :— 


Bs ee 
Books, Periodicals, and Maps purchased .... 58 0O 11 
Binding of Books and Mounting of Maps.... 145 16 7 


£203 17 6 


MusEvumM. 


One addition has been made to the collections during the past 
year: this is a specimen of sound oak found in blue clay, 15 feet 
below low-water mark, in sinking the cylinders for Chepstow 
Railway-bridge, and presented by J. G. Wood, Hsq., F.G.S. 

Mr. C. Davies Sherborn reports that, owing to various circum- 
stances, he was unable, during the last twelve months, to make much 
progress with the work of labelling and registering the type- and 
other important specimens in the Foreign Collection. Nevertheless, 
the Australian Collection, formed by Thomas Livingston Mitchell, 
has been catalogued. This consists of 474 specimens, 6 of which 
are figured types, while the remainder is purely of historical 
interest: it forms the first systematic collection from Australia, and 
is all described and enumerated in ‘ Papers relative to Geological 
Surveys—New South Wales, 1851.’ Originally there were 590 
specimens, but only 474, as above mentioned, remain: these are 
now all properly registered and accounted for. 

Mr. Sherborn confidently hopes to complete the work in the early 
part of the present year. 

The total Expenditure incurred in connexion with the Museum 
during 1898 was as follows :— 


2 ie 2) 
Special work (registration, ete.) .......... o> “Oro 
DUMGRICR So oS le Soe a ge eee niece ize 


£16 12 7G 


Vol. 55.| ANNUAL REPORT. . XV 


The appended Lists contain the Names of Government Depart- 
ments, Public Bodies, Societies, Editors, and Personal Donors, from 
whom Donations to the Library have been received during the past 
year :— 


I. GovrRNMENT DEPARTMENTS AND OTHER Pustiic Boptes. 


American Museum of Natural History. New York. 

Australian Museum. Sydney. 

Austria.—Kaiserlich-kénigliche Geologische Reichsanstalt. Vienna. 

Kaiserlich-kénigliches Naturhistorisches Hofmuseum. Vienna. 
Baden.—Grossherzogliches Ministerium des Innern: Geologische Landesanstalt. 

Heidelberg. 

Bavaria.—Koniglich Bayerisches Oberbergamt. Munich. 
Berlin.—KoOnigliche Preussische Akademie der Wissenschaften. 

‘. Birmingham.—Mason University College. 
Buenos Aires. Museo Nacional. 
California.—State Mining Bureau. San Francisco. 
California University. Berkeley. 
Cambridge (Mass.)—Museum of Comparative Zoology, Harvard College. 
Canada.— Geological and Natural History Survey. Ottawa. 
Chicago.—‘ Field’ Columbian Museum. 
Costa Rica.—Museo Nacional. San José. 
Dublin.—Royal Irish Academy. 
Europe.—Commission Géologique Internationale. Berlin. 
Finland.—Finlands Geologiska Undersékning. Helsingfors. 
France.—Muinisteére des Travaux Publics. Paris. 
——. Muséum d’Histoire Naturelle. Paris. 
——. Service de la Carte Géologique. Paris. 
Germany.—Kaiserliche Leopoldinisch-Carolinische Deutsche Akademie der 

Naturforscher. Halle. 

Great Britain—Admiralty. London. 

Army Medical Department. London. 

British Museum (Natural History). London. 

Colonial Office. London. 

Geological Survey. London. 

Home Office. London. 

Ordnance Survey. Southampton. 

Hesse .—Grossherzogliches Ministerium des Innern: Geologische Landesanstalt. 

Darmstadt. 

Holland.—Departement van Kolonien. The Hague. 

Houghton (Mich.).—Michigan Mining School. 

Hungary.—Kéonigliche Ungarische “Geologische Anstalt pee Féldtani 

Tarsulat). Budapest. 

India.—Geological Survey. Calcutta. 

——. India Office. London. 

Public Works Department. Calcutta. 

Indiana.—Geological Survey. Indianapolis. 

Iowa.—Geological Survey. Des Moines. 

Italy.—Reale Comitato Geologico. Rome. 

Kansas.— University Geological Survey. Topeka. 

Kingston (Canada).—Queen’s College. 

La Plata Museum. La Plata. 

Lausanne University. 

London.—City of London College. 

—. Royal College of Surgeons. 

University College. 

Manchester.—Owens College. 

Mexico.—Comision Geolégica. Mexico. 

Munich.—Ko6nigliche Bayerische Akademie der Wissenschaften. 

New South Wales.—Agent-General for, London. 

——. Department of Lands. Sydney. 

——. Department of Mines. Sydney. 

—. Geological Survey. Sydney. 


J Hh 


xV1 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


New York State Library. Albany. 

Museum. Albany. 

New Zealand.—Department of Mines. Wellington. 

Norway.—Meteorological Department. 

Norges Geologiska Undersékning. Christiania. 
Nova Scotia.—Department of Mines. Halifax. 
Padua.—Reale Accademia di Scienze, Lettere, ed Arti. 

_Palermo.—Reale Accademia di Scienze, Lettere, ed Arti. 
Paris.—Académie des Sciences. 

Perak Government. ‘Taiping. 

Pisa.—Royal University. 
Portugal.—Commissio Geologica. Lisbon. 
Queensland.—Department of Mines. Brisbane. 

Geological Survey. Brisbane. 

Rio de Janeiro. Museu Nacional. 

Rome.—Reale Accademia dei Lincei. 

Rumania.—Museum of Geology and Paleontology. Bucharest. 

Russia.—Comité Géologique. St. Petersburg. 

Section géologique du Cabinet de S.M. ’Empereur. St. Petersburg. 

Saxony.—Geologische Landesuntersuchung des Konigreichs Sachsen. Leipzig. 

South Australia.—A¢ent-General for, London. 

Spain.—Comision del Mapa Geoldégico. Madrid. 

St. Petersburg.—Académie Impériale des Sciences. 

Stockholm.—Kongliga Svenska Vetenskaps Akademi. 

Sweden.—Sveriges Geologiska Undersékning. Stockholm. 

Tokio.—Imperial University. 

Tufts College, Massachusetts. 

Turin.—Reale Accademia delle Scienze. 

United States.—Geological Survey, Washington. 

—— National Museum. Washington. 

Upsala University. 

Mineralogical and Geological Institute. 

Victoria.—Department of Agriculture. Melbourne. 

Department of Mines. Melbourne. 

Vienna.—Kaiserliche Akademie der Wissenschaften. 

Washington (D.C.).—Smithsonian Institution. 

Western Australia.—Agent-General for, London. 

—. Department of Mines. Perth. 

—. Geological Survey. Perth. 


Il. SocretrEs AND EDITORS. 


Acireale.—Accademia di Scienze. 

Adelaide.—Royal Society of South Australia. 

Alnwick.—Berwickshire Naturalists’ Club. 

Bahia.—Instituto Geographico e Historico. 

Barnsley.—Midland Institute of Mining, Civil and Mechanical Engineers. 
Belfast Natural History and Philosophical Society. ‘ 
Berlin.—Deutsche Geologische Gesellschaft. 

Gesellschaft Naturforschender Freunde. 

Zeitschrift fiir Praktische Geologie. 

Bern.—Schweizerische Naturforschende Gesellschaft. 

Bombay Branch of the Royal Asiatic Society. 

Bordeaux.—Société Linnéenne. 

Boston (Mass.).—American Academy of Arts and Sciences. 

Boston Society of Natural History. 

Brussels.—Société Belge de Géologie, de Paléontologie et d’Hydrologie. 
Société Malacologique de Belgique. 

Budapest.—Féldtani Kozlony (Geological Magazine). 

Buenos Aires.—Instituto Geografico Argentino. 

—. Sociedad Cientifica Argentina. 

Caen.—Société Linnéenne de Normandie. 

Calcutta.—Indian Engineering. 

Asiatic Society of Bengal. 

Cape Town.—-South African Philosophical Society. 


Wol. 55. | ANNUAL REPORT. xvii 


Cardiff—South Wales Institute of Engineers. 
Chicago.—Journal of Geology. 

Christiania.—Nyt Magazin for Naturvidenskaberne. 
Videnskabernes Selskab. 

Cincinnati Society of Natural History. 

Copenhagen.—Kongelige Danske Videnskabernes Selskab. 
Cérdoba (Argentine Republic)—Academia Nacional de Ciencias. 
Cracow.—Académie des Sciences (Akademja Umiejetosci). 
Darmstadt.—Verein fiir Erdkunde. 

Douglas.—Isle of Man Natural History and Antiquarian Society. 
Dresden.—Naturwissenschaftliche Gesellschaft ‘ Isis.’ 

—. Verein fiir Erdkunde. 

Dublin.—Royal Dublin Society. 

Edinburgh.—Geological Society. 

—. Royal Physical Society. 

—. Royal Scottish Geographical Society. 

—. Royal Society. 

Ekaterinburg.—Société Ouralienne d’Amateurs des Sciences Naturelles. 
Falmouth.—Royal Cornwall Polytechnic Society. 

Felsted School Scientific Society. 

Frankfurt a. M.—Senckenbergische Naturforschende Gesellschaft. 
Freiburg i. B.—Naturforschende Gesellschaft. 
Giessen.—Oberhessische Gesellschaft fiir Natur- und Heilkunde. 
Gloucester.—Cotteswold Naturalists’ Field-Club. 
Haarlem.—Société Hollandaise des Sciences. 
Halitax.—Yorkshire Geological and Polytechnic Society. 

(N. 8.).—Nova Scotian Institute of Science. 

Hamilton (Canada).—Hamilton Association. 

Havre.—Société Géologique de Normandie. 
Hermannstadt.—Siebenbirgischer Verein fiir Naturwissenschaften. 
Hertford.—Hertfordshire Natural History Society. 
Hobart.—Royal Society of Tasmania. 

Indianapolis.—Indiana Academy of Science. 
Johannesburg.—Geological Society of South Africa. 
Kiev.—Société des Naturalistes. 

Lausanne.—Société Géologique Suisse. 

—. Société Vaudoise des Sciences Naturelles. 
Leeds.—Philosophical Society. 

Leicester.—Literary and Philosophical Society. 
Leipzig.—Naturwissenschaftlicher Verein fiir Sachsen und Thiringen. 
Zeitschrift fiir Krystallographie und Mineralogie. 
Zeitschrift fiir Naturwissenschaften. 

Liége.—Société Géologique de Belgique. 

. Société Royale des Sciences. 

Lille.—Société Géologique du Nord. 

Lisbon.—Sociedade de Geographia. 

Liverpool.—Literary and Philosophical Society. 
London.—Academy. 

Athenzum. 

British Association for the Advancement of Science. 
British Association of Waterworks Engineers. 

Chemical News. 

Chemical Society. 

Colliery Guardian. 

East India Association. 

Geological Magazine. 

Geologists’ Association. 

Institution of Civil Engineers. 

Iron and Steel Trades’ Journal. 

Knowledge. 

Linnean Society. 

London, Edinburgh, and Dublin Philosophical Magazine. 
Mineralogical Society. 

Nature. 

Paleontographical Society. 

Ray Society. 

Royal Agricultural Society. 


XVill PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


London.—Royal Astronomical Society. 

Royal Geographical Society. 

Royal Institution. 

Royal Meteorological Society. 

Royal Microscopical Society. 

Royal Photographic Society of Great Britain. 

Royal Society. 

Society of Arts. 

Society of Biblical Archeology. 

Society of Public Analysts. 

Victoria Institute. 

Zoological Society. 

Madison (Wis. ).—Wisconsin Academy of Sciences. 

Manchester.—Geological Society. 

Literary and “Philosophical Society. 

Melbourne.—Royal Society of Victoria. 

Milan.—Reale Istituto Lombardo di Scienze e Lettere. 

Montreal.—Natural History Society. 

Moscow.—Société Impériale des Naturalistes. 

Nancy.—Académie de Stanislas. 

New Haven (Conn.)—American Journal of Science. 

New York.—Academy of Sciences. 

——. American Institute of Mining Engineers. 

Newcastle-upon-Tyne.—North of England Institute of Mining and Mechanical 
Engineers. 

Northampton.—Northamptonshire Natural History Society. 

Niirnberg.—Naturhistorische Gesellschaft. 

Ottawa. Royal Society of Canada. 

Palermo.—Annales de Géologie et de Paléontologie. 

Paris.—Annuaire Géologique Universel. 

——. Revue Scientifique. 

——. Société Frangaise de Minéralogie. 

—. Société Géologique de France. 

Spelunca. 

Penzance.—Royal Geological Society of Cornwall. 

Philadelphia.—Academy of Natural Sciences. 

American Philosophical Society. 

Wagner Free Institute of Science. 

Pisa.—Societa Toscana di Scienze Naturali. 

Plymouth.—Devonshire Association for the Advancement of Science. 

Rochester (N.Y.).—Geological Society of America. 

Rome.—Societa Geologica Italiana. 

Rugby School Natural History Society. 

Santiago de Chile-—Sociedad Nacional de Mineria. 

. Société Scientifique du Chili. 

Scranton (Pa.).—Colliery Engineer. 

Shanghai.—China Branch of “the Royal Asiatic Society. 

St. Peter sburg.—Russische Kaiserliche Mineralogische Gesellschaft. 

Stockholm.—Geologiska Férening. 

Stuttgart.—Neues Jahrbuch fiir Mineralogie, Geologie und Palaontologie. 

—. Verein fiir Vaterlandische Naturkunde in Wirttemberg. 

Sydney.—Australasian Institute of Mining Engineers. 

—. Linnean Society of New South Wales. 

Royal Society of New South Wales. 

Topeka.—Transactions of the Kansas Academy of Science. 

Toronto.—Canadian Institute. 

Toulouse.—Société d’ Histoire Naturelle. 

Truro.—Royal Institution of Cornwall. 

Vienna.—Berg- und Huittenmannisches Jahrbuch. 

—. Kaiserlich-kénigliche Zoologisch-botanische Gesellschaft. 

—. Mimneralogische und Petrographische Mittheilungen. 

Washington (D.C.).—Biological Society. 

Wellington (N.Z.).—New Zealand Institute. 

Wiesbaden.—Nassauischer Verein fiir Naturkunde. 

York.—Natural History Journal. 

—. Yorkshire Philosophical Society. 


I aaa 


Vol. 55.} 


Aburrow, C. 
Agassiz, A. 
Aguilar, R. 
Ameghino, F. 
Ami, H. M. 
Argyll, Duke of. 
Arnold, J. 
Arthaber, G. von. 


Bauerman, H. 
Baur, G. 
Beecher, C. E. 
Belinfante, L. L. 
Bewick, T. B. 
Bigot, A. 
Blake, J. F. 
Blake, W. P. 
Bohm, A. von. 
Bolton, H. 
Bonney, T. G. 
Boule, M. 
Boulton, W. S. 
Branner, J. C. 
Bright, C. 
Brogger, W. C. 
Brown, H. Y. L. 
Brush, G. J. 
Brusina, S. 
Buckman, S. S. 


Carez, L. 
Champion, H. 
Chapman, F 
Choffat, P. 
Clark, W. B. 
Claypole, E. W. 
Clements, J. M. 
Coghlan, T. A. 
Cole, G. A. J. 
Collins, J. H. 
Cornish, V. 
Cortese, E. 
Credner, H. 
Crick, G. C. 
Croix, J. E. de la. 
Cumenge, E. 


Dames, W. 
Davis, W. H. 
Davis, W. M. 
Davison, C. 
Dawson, G. M. 
Dawson, Sir J. W. 
Delachaux, E. 8. 
Delebecque, A. 
Delgado, J. F. N. 
Derby, O. A. 
Dewalque, G. 
Dollfus, G. F. 
Donald, Miss J. 
Douglas, J. 
Dowker, G. 
Draper, D. 
Dunlop, A. 


ANNUAL REPORT. 


II]. Pxrrsonat Donors. 


Eastman, C. R. 
Etheridge, R., Jun. 
Evans, Sir J. 


Fairchild, H. L. 
Fairley, T. 

Feilden, Col. H. W. 
Fordham, H. G. 
Foster, C. Le N. 
Box; EH: 

Francis, W. 

Frazer, P. 


Garrard, J. J. 
Garwood, H. J. 
Gautier, P. 
Geikie, Sir A. 
Geinitz, H. B. 
George, W. J. 
Gilpin, E., Jun. 
Goodchild, J. G. 
Gosnell, R. E. 
Gosselet, J. 
Greenwell, A. 
Gregorio, A. de. 
Gresley, W.S. 
Griffith, P. 
Ginther, A. 
Guppy, R. J. L. 


Hanks, H. G. . 
Harcourt-Smith, J. 
Harlé, E. 
Harrison, J. B. 
Harrison, W. J. 
Hatch, F. H. 
Haverly, C. E. 
Hawell, J. 
Herries, R. S. 
Hill, W. 
Hind,-W. 
Hinde, G. J. 
Hodson, F. W. 
Hodson, G. 
Hogbom, A. G. 
Holland, P. 
Holland, T. H. 
Holmquist, P. J. 
Hoskold, H. D. 
Hovey, E. O. 
Howard, F. T. 


Jones, T. R. 
Jordan, H. K. 
Judd, J. W. 
Jukes-Browne, A. J. 


Kayser, E. 
Kennard, A. 8. 
Kindle, E. M. 
Koch, A. 
K6nen, A. von. 
Kort, W. 
Kossmat, F. 


xix 


Lacroix, A. 
Lapparent, A. de. 
Lebesconte, P. 
Liversidge, A. 


Lyman, B.S. 


Maitland, A.G. 
Malaise, C. 
Manson, M. 
Mantle, H. G. 
Markham, Sir C. R. 
Marr, J. E. 

Marsh, O. C. 
Martin, E. A. 
Maslen, A. J. 
Matley, C. A. 

Meli, R. 

Merriam, J. C. 
Merrill, G. P. 
Mojsisovics, E. von. 
Monckton, H. W. 
Morton, G. H. 
Munthe, H. 


Nares, Sir G. S. 
Newton, E. T. 
Newton, R. B. 
Nordenskjold, O. 


(Ehlert, D. P. 
Omboni, G. 


Packard, A. 8. 
Penck, A. 
Penfield, S. L. 
Perkins, H. I. 
Petterd, W. F. 
Phillips, A. G. 
Plumb, C. P. 
Prestwich, Lady. 
Pretto, O. de. 


Ramond, G. 
Reade, T. M. 
Regan, W. F. 
Reid, C. 
Renevier, E. 
Richard, A. de. 
Richter, E. 
Ritter, E. 
Robellaz, F. 
Rosenbusch, H. 
Rothpletz, A. 


Salinas, E. 
Salter, A. E. 
Sarauw, G. F. L. 
Sars, G. O. 
Sauvage, H. EH. 
Sawyer, A. R. 
Schardt, H. 


xx 


Sernander, R. 
Seward, A. C. 
Shaler, N.S. 
Sheppard, T. 
Skvortzov, J. 
Small, E. W. 
Sorby, H. C. 
Spencer, J. W. 
Stefanescu, G. 
Stephens, J. 
Strahan, A. 
Suess, E. 


Taber, C. A. M. 


PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 


Teall, J. J. H. 
Teisseyre, W. 
Thompson, B. 
Toll, E. von. 
Topley, Mrs. 
Traquair, R. H. 
Tucker, W. T. 


Twelvetrees, W. H. 


Tyrrell, J. B. 


Valentin, .J. 


Van den Broeck, EH. 


Walther, J. 


Ward, L. F. 
Wardle, Sir T. 
Warren, H. 
Watts, W. W. 
Whitaker, W. 
White, J.C. 
Wilkinson, W. F. 
Wilson, E. 
Wiman, C. 
Woodward, B. B. 
Woodward, H. 
Woodward, H. B. 


Zittel, K. A. von. 


[May 1899, 


Vol. 55.] ANNUAL REPORT. xxl 


CoMPARATIVE STATEMENT OF THE NUMBER OF THE SOCIETY AT THE 
CLOSE OF THE YEARS 1897 anp 1898. 


Dec. 31st, 1897. Dec. 31st, 1898. 
Compounders...... Recah ZOSIRE. Melee sin 291 
Contributing Fellows...... SOB ae oe ative are 911 
Non-contributing Fellows. . COTY Beate. 58 
1256 1260 
Foreign Members ........ DO, aes 37 
Foreign Correspondents.... OO) Rear 39 
1333 1336 


Comparative Statement explanatory of the Alterations in the Number 
of Fellows, Foreign Members, and Foreign Correspondents at the 
close of the years 1897 and 1898. - 


Number of Compounders, Contributing and Non- 1956 
contributing Fellows, December 31st, 1897 .. 


Add Fellows elected during the former year fee 17 
[einGl ga ISI ch SA Sees Rts ae ee me fs 
Add Fellows elected and paid in 1898 ........ 4] 
1314 
Deduct Compounders deceased................ 8 
Compounders elected Foreign Members.... 2 
Contributing Fellows deceased .......... 18 
. Non-contributing Fellows deceased ...... 2 
Contributing Fellows resigned .......... 16 
Contributing Fellows removed .......... 8 
— 54 
1260 


Number of Foreign Members and oe a 
Correspondents, December 31st,1897 .... 

Deduct Foreign Members deceased ........ 
Foreign Correspondent deceased... .. 
Foreign Correspondent elected 

Foreign Memiberi¢ . ..< 2... »/am } 


HE EON 


Add Foreign Members elected .............. 
Foreign Correspondents elected ........ 


lwo S| x 


ls 


1336 


| 


XXli PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


DrcEAsED FELtows. 


Compounders (8). 


Barber, C. A., Esq. Oakley, C., Esq. 
Bosworth, J. A., Esq. Ormerod, H. M., Esq. 
Goodenough, Lt.-Gen. Sir W. H. | Walker, W., Esq. 
Lucy, W. C., Esq. Wilson, E., Esq. 
Resident and other Contributing Fellows (18). 
Atherstone, Dr. W. G. Hayter, H., Esq. 
Attwood, M., Ksq. Hosken, J. R., Esq. 
Bell, D., Esq. Hyland, Dr. J. 8. 
Brown, R., Esq. Johnson, J. H., Esq. 
Clark, G..7., Msq. 5 Learoyd, 8., Esq. 
Foggin, W., Esq. Moore, J. C.,, Esq. 
Fowler, Sir J. Potts, J., Esq. 
Goadby, Rev. J. J. )* | Searth, Wi. W., Wse: 
Grimes, J. E., Hisq. Sopwith, T., Esq. 


Non-contributing Fellows (2). 
Colchester, W., Esq. | Gould, C., Esq. 


Foreign Members (5). 


Dames, Prof. W. B. Marcou, M. J. | 
Giimbel, Prof. C. W. von. Sandberger, Prof. F. von. 
Hall, Prof. J. 


Foreign Correspondent (1). 
Briart, M. A. 


Frettows Restenep (16). 


Asano, N., Esq. Macdonald, 8. D., Esq. 


Baxter, W. E., Esq. Mackinnon, A., Esq. 
Edwards, W. B. D., Esq. Malan, Rey. A. N. 
Eustice, G. W., Esq. Mawer, W., Esq. 
Faweett, E. A. S., Esq. Stubbins, J., Esq. 
Ferrier, C. A., Esq. Thomas, J. G., Esq. 
Gordon, Rey. C. R. Warburton, T., Esq. 
TAnson, J. C., Esq. Workman, W. P., Esq. 


Fr~Lows (CoMPoUNDERS) ELECTED Forrrtcn Mempers (2). 
Marsh, Prof. O. C. | Walcott, C. D., Esq. 


Vol. 55. ] ANNUAL REPORT. XXlil 


Frttows Removep (8). 


Clarke, W. H., Esq. Lefroy, G. A., Esq. 
Dent, G., Esq. Taylor, R., Esq. 
Dowen, Rev. Z. T. Williams, W. J., Esq. 
Kemper-Voss, E., Esq. Woodhouse, A., Esq. 


The following Personages were elected Foreign Members during the 
; year 1898 :— 


Prof. Hermann Creduer, of Leipzig. 
Prof. Othniel Charles Marsh, of New Haven, Conn. (U.S.A.). 
Mr. Charles Doolittle Walcott, of Washington, D.C. (U.S.A.). 


The following Personages were elected Foreign Correspondents during 
the year 1898 :— 


M. Marcellin Boule, of Paris. 
Dr. W. H. Dall, of Washington, D.C. (U.S.A.). 
M. A. Karpinsky, of St. Petersburg. 


After the Reports had been read, it was resolved :— 

That they be received and entered on the Minutes of the Meeting, 
and that such parts of them as the Council shall think fit be printed 
and circulated among the Fellows. 


It was afterwards resolved :— 


That the thanks of the Society be given to Prof. T. G. Bonney 
and J.J. H. Teall, Esq. (the latter retiring also from the Council), 
retiring from the office of Vice-President. 


That the thanks of the Society be given to Prof. W. Boyd 
Dawkins, J. E. Marr, Esq., Prof. H. A. Miers, and E. T. Newton, 


Esq., retiring from the Council. 


After the Balloting-glasses had been closed, and the Lists examined 
by the Scrutineers, the following gentlemen were declared - to 
have been duly elected as the Officers and Ceuncil for the ensuing 


year :— 


VOL. LV 


XXIV PROCEEDINGS OF THE GEOLOGICAL sociETy. [May 1899, 


OFFICERS AND COUNCIL.—1899. 


PRESIDENT. 
W. Whitaker, Esq., B.A., F.R.S. 


VICE-PRESIDENTS. 


Henry Hicks, M.D., F.R.S. 

Prof. J. W. Judd, C.B., LL.D., F.R.S. 

Prof. W. J. Sollas, M.A., D.Se., LL.D., F.R.S. 
Rev. H. H. Winwood, M.A. 


SECRETARIES. 


R. 8. Herries, Esq., M.A. 
Prof. W. W. Watts, M.A. 


FOREIGN SECRETARY. 
Sir John Evans, K.C.B., D.C.L., LL.D., F.R.S., F.L.S. 


TREASURER. 
W. T. Blanford, LL.D., F.R.S. 


er 


COUNCIL. 

W. T. Blanford, LL.D., F.B.S. W.H. Hudleston, Esq., M.A., F.R.S., 
Prof. T. G. Bonney, D.Sc., LL.D.,| F-.L.S. 

E.R.S. Prof. J. W. Judd, C.B., LL.D., F.R.S. 
Sir John Evans, K.C.B., D.C.L., | H. W. Monckton, Esq., F.L.S. 

LL.D., F.R.S. F. W. Rudler, Esq. 
EK. J. Garwood, Esq., M.A. Prof. H. G. Seeley, F.R.S., F.L.S. 
J. W. Gregory, D.Sc. A. C. Seward, Esq., M.A., F.R.S. 
Alfred Harker, Esq., M.A. Prof. W. J. Sollas, M Ap iises 
F. W. Harmer, Esq. LED. EES. 
R. 8. Herries, Esq., M.A. A. Strahan, Esq., M.A. 
Henry Hicks, M.D., F.R.S. Prof. W. W. Watts, M.A. 
Rev. Edwin Hill, M.A. W. Whitaker, Esq., B.A., F.R.S. 
G. J. Hinde, Ph.D., F.R.S. Rev. H. H. Winwood, M.A. 


A. 8. Woodward, Esq., F.L.S. 


ASSISTANT-SECRETARY, CLERK, LIBRARIAN, AND CURATOR. 
L. L. Belinfante, M.Sc. 


ASSISTANTS IN OFFICE, LIBRARY, AND MUSEUM. 


W. Rupert Jones. 
Clyde H. Black. 


Vol. 55. | ANNUAL REPORT. XXV 


LIST OF 


THE FOREIGN MEMBERS 


OF THE GEOLOGICAL SOCIETY OF LONDON, 1w 1898. 


Date of 
Election. 


1848. Prof. James Hall, Albany, N.Y., U.S.A. (Deceased.) 
1856. Prof. Robert Bunsen, For. Mem. R.8., Hezdelberg. 
1857. Prof. H. B. Geinitz, Dresden. 
1871. Dr..Franz Ritter von Hauer, Vienna. 
1874, Prof. Albert Gaudry, Paris. 
1875. Prof. Fridolin von Sandberger, Wiirzburg. (Deceased.) 
1877. Prof. Carl Wilhelm yon Giimbel, Munich. (Deceased.) 
1877. Prof. Eduard Suess, Vienna. 
1879. M. Jules Marcou, Cambridge, Mass., U.S.A. (Deceased.) 
1880. Prof. Gustave Dewalque, Lvége. ; 
1880. Baron Adolf Erik Nordenskiold, Stockholm. 
1880. Prof. Ferdinand Zirkel, Lezpzig. 
1883. Prof. Otto Martin Torell, Stockholm. 
1884. Prof. G. Capellini, Bologna. 
1885. Prof. Jules Gosselet, Lille. 
1886. Prof. Gustav Tschermak, Vienna. 
1887. Prof. J. P. Lesley, Philadelphia, Pa., U.S.A. 
1888. Prof. Kugéne Renevier, Lausanne. 
1888. Baron Ferdinand von Richthofen, Bern. 
1889. Prof. Ferdinand Fouqué, Paris. . 
1889. Geheimrath Prof. Karl Alfred von Zittel, Munich. 
1890. Prof. Heinrich Rosenbusch, Hevdelberg. 
1891. Dr. Charles Barrois, Zvile. 
1892. Prof. Gustav Lindstrom, Stockholm. 
1893. Prof. Waldemar Christofer Brogger, Christiania. 
1893. M. Auguste Michel-Lévy, Parvs. 
1893. Dr. Edmund Mojsisovics von Mojsvar, Vienna. 
1893. Dr. Alfred Gabriel Nathorst, Stockholm. 
1894. Prof. George J. Brush, New Haven, Conn., U.S.A. 
1894. Prof. Edward Salisbury Dana, New Haven, Conn., U.S.A. 
1894. Prof. Alphonse Renard, Ghent. 
1895. Prof. Wilhelm Barnim Dames, Berlin. (Deceased.) 
1895. Prof. Grove K. Gilbert, Washington, D.C., U.S.A. 
1895. M. Friedrich Schmidt, S¢. Petersburg. 
1896. Prof. Albert Heim, Ziirich. 
1897. M. E. Dupont, Brussels. 
1897. Dr. Anton Fritsch, Prague. 
1897. Prof. A. de Lapparent, Paris. 
1897. Dr. Hans Reusch, Christiania. 
1898. Geheimrath Prof. Hermann Credner, Lezpzig. 
1898. Prof. O. C. Marsh, New Haven, Conn., U.S.A. Deceased.) 
1898. Mr. C. D. Walcott, Washington, D.C., U.S.A. 
¢2 


XXVi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


LIST OF 
THE FOREIGN CORRESPONDENTS 


OF THE GEOLOGICAL SOCIETY OF LONDON, rw 1898. 


Date of 
Election. 


1866. Prof. Victor Raulin, Montfaucon d’ Argonne. 
1874. Prof. Igino Cocchi, Florence. 

1879. Dr. Emile Sauvage, Boulogne-sur-Mer. 

1882, Prof. Louis Lartet, Toulouse. 

1882. Prof. Alphonse Milne-Edwards, Paris. 

1884. M. Alphonse Briart, Morlanwelz. (Deceased.) 
1887. Senhor J. F. N. Delgado, Lisbon. 

1888, M. Charles Brongniart, Paris. 

1888. M. Ernest Van den Broeck, Brussels. 

1889. M. R. D. M. Verbeek, Padang, Sumatra. 

1890. M. Gustave F. Dollfus, Paris. 

1890. Herr Felix Karrer, Vienna. 

1890. Prof. Adolph von Konen, Gottingen. 

1891. Prof. Emmanuel Kayser, Marburg. 

1892. Prof. Johann Lehmann, Kel. 

1892. Major John W. Powell, Washington, D.C., U.S.A. 
1893. Prof. Marcel Bertrand, Paris. 

1898. Prof. Aléxis Pavlow, Moscow. 

1898. M. Ed. Rigaux, Boulogne-sur-Mer, 

1893. Dr. Sven Leonhard Tornquist, Lund. 

1893. Dr. Charles Abiathar White, Washington, D.C., U.S.A. 
1894. Prof. Joseph Paxson Iddings, Chicago, Ill., U.S.A. 
1894. M. Perceval de Loriol-Lefort, Campagne Frontenex. 
1894. Dr. Francisco P. Moreno, La Plata. 

1894. Prof. A. Rothpletz, Munich. 

1894. Prof. J. H. L. Vogt, Christiania. 

1895. Prof. Paul Groth, Munich. 

1895. Prof. K. de Kroustchoff, S¢. Petersburg. 

1895. Prof. Albrecht Penck, Vienna. 

1896, Prof. S. L. Penfield, New Haven, Conn., U.S.A. 
1896. Prof. J. Walther, Jena. 

1897. M. Louis Dollo, Brussels. 

1897. Mr. A. Hyatt, Cambridge, Mass., U.S.A. 

1897. Prof. Anton Koch, Budapest. 

1897. Prof. A. Lacroix, Paris. 

1897. M. Emmanuel de Margerie, Paris. 

1897. Prof. Count H. zu Solms-Laubach, Strasburg. 
1898. M. Marcellin Boule, Paris. 

1898. Dr. W. H. Dall, Washington, D.C., U.S.A. 

1898. M.A. Karpinsky, St. Petersburg. 


Mole? 5'53| ANNUAL REPORT. XXVll 


AWARDS OF THE WOLLASTON MEDAL 


UNDER THE CONDITIONS OF THE ‘DONATION FUND’ 
ESTABLISHED BY 
WILLIAM HYDE WOLLASTON, M.D., FE.R.S., F.G.S., erc. 


*To promote researches concerning the mineral structure of the earth, and to 
enable the Council of the Geological Society to reward those individuals of any 


country by whom such researches may hereafter be made,—‘ such individual not 
being a Member of the Council.’ 
1831. Mr. William Smith. 1866. Sir Charles Lyell. 
1835, Dr. G. A. Mantell. 1867. Mr. G. Poulett Scrope. 
1836, M. Louis Agassiz. 1868. Prof. Carl F. Naumann, 
1837. eee T. P. Cautley. 1869. Dr. H. C. Sorby. 
Dr. H. Falconer. 1870. Prof. G. P. Deshayes. 
1838. Sir Richard Owen. 1871. Sir A. C. Ramsay. 
1839. Prof. C. G. Ehrenberg. 1872. Prof. J. D. Dana. 
1840. Prof. A. H. Dumont. 1873. Sir P. de M. Grey Egerton. 
1841. M. Adolphe T. Brongniart. | 1874. Prof. Oswald Heer. 
1842. Baron L. von Buch. 1875. Prof. L. G. de Koninck. 
1843. te Elie de Beaumont. 1876. Prof. T. H. Huxley. 
M. P. A. Dufrénoy. 1877. Mr. Robert Mallet. 
1844, Rev. W. D. Conybeare. 1878. Dr. Thomas Wright. 
1845. Prof. John Phillips. 1879. Prof. Bernhard Studer. 
1846. Mr. William Lonsdale. 1880. Prof. Auguste Daubrée. 
1847. Dr. Ami Boué. 1881. Prof. P. Martin Duncan. 
1848. Very Rev. W. Buckland. 1882. Dr. Franz Ritter von Hauer. 
1849. Sir Joseph Prestwich. 1883. Dr. W. T. Blanford. 
1850. Mr. William Hopkins. 1884. Prof. Albert Gaudry. 
1851. Rey. Prof. A. Sedgwick. 1885. Mr. George Busk. 
1852. Dr. W. H. Fitton. 1886. Prof. A.L.O. Des Cloizeaux. 
1853, ee le Vicomte A. d’Archiac. | 1887. Mr. J. Whitaker Hulke. 
M. E. de Verneuil. 1888. Mr. H. B. Medlicott. 
1854, Sir Richard Griffith. 1889. Prof. T. G. Bonney. 
1855. Sir H. T. De la Beche. 1890. Prof. W. C. Williamson. 
1856, Sir W. E. Logan. 1891. Prof. J. W. Judd. 
1857. M. Joachim Barrande. 1892. Baron Ferdinand von 
Herr Hermann von Meyer. Richthofen. 
1858. Mr. James Hall. 1893. Prof. N. 8. Maskelyne. 
1859. Mr. Charles Darwin. 1894. Prof. Karl Alfred von Zittel 
1860. Mr. Searles V. Wood. 1895. Sir Archibald Geikie, 
1861. Prof. Dr. H. G. Bronn. 1896. Prof. Eduard Suess. 
1862. Mr. R. A.C. Godwin-Austen. | 1897. Mr. W. H. Hudleston. 
1863. Prof. Gustav Bischof, 1898. Prof. F. Zirkel. 
1864, Sir R. I. Murchison. 1899. Prof. Charles Lapworth. 


1865. Dr. Thomas Davidson. 


XXVili 


AWARDS 


PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 


OF THE 


[May 1899, 


BALANCE OF THE PROCEEDS OF THE WOLLASTON 


1831. 
1833. 
1834. 
1835. 
1836. 
1838. 
1839. 
1840. 
1841. 
1842. 
1843. 
1844. 
1845. 
1846. 
1847. 


1848. 


1849. 
1850. 
1851. 
1852. 
1855. 
1854. 
1855. 
1856. 
1857. 
1858. 
1859. 


1860. 


1861. 
1862. 
1863. 
1864. 
1865. 


“DONATION 


Mr. William Smith. 
Mr. William Lonsdale. 
M. Louis Agassiz. 

Dr. G. A. Mantell. 
Prof. G. P. Deshayes. 
Sir Richard Owen. 
Prof. C. G. Ehrenberg. 
Mr, J. De Carle Sowerby. 
Prof. Edward Forbes. 
Prof. John Morris. 
Prof. John Morris. 

Mr. William Lonsdale. 
Mr. Geddes Bain. 

Mr. William Lonsdale. 
M. Alcide d’Orbigny. 


Cape-of-Good-Hope Fossils. 


M. Alcide d’Orbigny. 
Mr. William Lonsdale. 
Prof. John Morris. 

M. Joachim Barrande. 
Prof. John Morris. 

Prof. L. G. de Koninek. 
Dr. 8. P. Woodward. 

Drs. G. and F. Sandberger. 
Prof. G. P. Deshayes. 

Dr. 8. P. Woodward. 

Prof. James Hall. 

Mr. Charles Peach. 

Prof. T. Rupert Jones. 
a W. K. Parker. 
Prof. Auguste Daubrée. 
Prof. Oswald Heer. 
Prof. Ferdinand Senft. 
Prof. G. P. Deshayes. 
Mr. J W. Salter. 


1866. 
1867. 
1868. 
1869. 
1870, 
1871. 
1872. 
1873. 
1874, 
1875. 
1876. 
| 1877. 

1878. 
1879. 
1880. 
1881. 
1882. 
1883, 
1884, 
1885. 
1886, 
1887. 
1888, 
1889. 
1890. 
1891. 
1892. 
1893. 
1894. 
1895. 
1896. 
1897. 
1898. 
1899. 


FUND.’ 


Dr. Henry Woodward. 
Mr. W. H. Baily. 

M. J. Bosquet. - 

Mr. William Carruthers, 
M. Marie Rouault. 

Mr. Robert Etheridge. 
Dr. James Croll. 

Prof. J. W. Judd. 

Dr. Henri Nyst. 

Prof, 1.0, Miall: 

Prof. Giuseppe Seguenza. 
Mr. R. Etheridge, Jun. 
Prof. W. J. Sollas. . 
Mr. Samuel Allport. 
Mr. Thomas Davies. 
Dr. R. H. Traquair. 

Dr. George J. Hinde. 
Prof. John Milne. 

Mr. E. Tulley Newton. 
Dr. Charles Callaway. 
Mr, J. Starkie Gardner. 
My. B. N. Peach. 

Mr. John Horne. 

Mr. A. Smith Woodward. 
Mr, W. A. E. Ussher. 
Mr. Richard Lydekker. 
Mr. Orville A. Derby. 
Mr. J. G. Goodchild. 
Mr. Aubrey Strahan. 
Prof. W. W. Watts. 
Mr. Alfred Harker. 

Mr. F. A. Bather. 

Mr. E. J. Garwood. 
Prof. J. B. Harrison. 


Vol. 55.] 


ANNUAL REPORT. 


XxX1xX 


AWARDS OF THE MURCHISON MEDAL 
AND OF THE 
PROCEEDS OF THE ‘MURCHISON GEOLOGICAL FUND,’ 


ESTABLISHED UNDER THE WILL OF THE LATE 
SIR RODERICK IMPEY MURCHISON, Barr., F.R.S., F.G-.S. 


‘To be applied in every consecutive year in such manner as the Council of the 
Society may deem most useful m advancing Geological Science, whether by 
granting sums of money to travellers in pursuit of knowledge, to authors of 
memoirs, or to persons actually employed in any enquiries bearing upon the 
science of Geology, or in rewarding any such travellers, authors, or other persons, 
and the Medal to be given to some person to whom such Council shall grant 
any sum of money or recompense in respect of Geological Science.’ 


1873. 
1873. 
1874. 
1874. 
1874. 
1875. 
1875. 
1876. 


1876. 
18i7. 
1877. 
1878. 
1878. 
1879. 
1879. 
1880. 


1881. 
1881. 
1882. 
1882. 
1883. 
1883. 
1884. 


1884. 
1885. 


1885. 
1886. 


Mr. William Davies. Medal. 

Prof. Oswald Heer. 

Dr. J. J. Bigsby. Medal. 

Mr. Alfred Bell. 

Prof. Ralph Tate. 

Mr. W. J. Henwood. Medal. 

Prof. H. G. Seeley. 

Mr. Alfred R. C. Selwyn. 
Medal. 

Dr. James Croll. 


Rev. W. B. Clarke. Medal. 
Rev. J. F. Blake. 
Prof. H. B. Geinitz. Medal. 


Prof. Charles Lapworth. 

Sir Frederick M‘Coy. Medal. 

Mr. J. W. Kirkby. 

Mr. Robert Etheridge. 
Medal. 

Sir Archibald Geikie. Medal. 

Mr. Frank Rutley. 

Prof. Jules Gosselet. Medal. 

Prof. T. Rupert Jones. 

Prof. H. R. Goppert. Medal. 

Dr. John Young. 

Dr. Henry Woodward. 
Medal, 

Mr. Martin Simpson. 

Dr. Ferdinand von Romer. 
Medal. 

Mr. Horace B. Woodward. 

Mr. William Whitaker. 
Medal. 


1886, 
1887. 
1887. 
1888. 


1888. 
1889. 
1889. 
1890. 
1890. 
1891. 
1891. 
1892. 
1892. 
1893. 
18953. 
1894, 
1894. 
1895. 


1895. 
1896. 


1896. 
1897. 


1897. 
1898. 
1898. 


1899. 
1899. 


Mr. Clement Reid. 

Rev. P. B. Brodie. 

Mr. Robert Kidston. 

Prof. J. 8. Newberry. 
Medal. 

Mr. Edward Wilson. 

Prof. James Geikie. Medai. 

Prof. Grenville A. J. Cole. 

Prof. Edward Hull. Medal. 

Mr. Edward Wethered. 

Prof.W. C. Brogger, Medal. 

Rev. Richard Baron. 

Prof. A. H. Green. Medal. 

Mr. Beeby Thompson. 

Rev. Osmond Fisher. Medal, 

Mr. G. J. Williams. 

Mr. W. T. Aveline. 

Mr. George Barrow. 

Prof. Gustav Lindstrom. 
Medal. 

Mr. A. C. Seward. 

Mr. T. Mellard Reade. 
Medal. 

Mr. Philip Lake. 

Mr. Horace B. Woodward. 
Medal. 

Mr.S. 8. Buckman. 

Mr. T. F. Jamieson. Medal. 

Miss Jane Donald. 

{ Mr. B.N. Peach. Medal. 


Medal. 


Medal 


Mr. John Horne. Medal. 
Mr. James Bennie. 


xxx 


PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 


[May 1899, 


AWARDS OF THE LYELL MEDAL 


AND OF THE 


PROCEEDS OF THE ‘LYELL GEOLOGICAL FUND,’ 


ESTABLISHED UNDER THE WILL AND CODICIL OF THE LATE 
SIR CHARLES LYELL, Barr., F.R.S., F.G.S. 


The Medal ‘to be given annually’ (or from time to time) ‘as a mark of honorary 
distinction and as an expression on the part of the governing body of the Society 
that the Medallist (who may be of any country or either sex) has deserved well 
of the Science, —‘ not less than one third of the annual interest [of the fund] to 
accompany the Medal, the remaining interest to be given in one or more portions 
at the discretion of the Council for the encouragement of Geology or of any of 
the allied sciences by which they shall consider Geology to have been most 
materially advanced, either for travelling expenses or for a memoir or paper 
published, or in progress, and without reference to the sex or nationality of the 
author, or the language in which any such memoir or paper may be written.’ 


1876. 
1877. 
Wee 
1878. 
1878. 


1879. 


1879. 


1879. 
1880. 


1880. 


1881. 
1881. 
1881. 
1882. 
1882. 
1882. 


1885. 
1888. 
1883. 
1884. 
1884. 
1885. 
1885. 
1886. 
1886. 
1887. 
1887. 


1888. 
1888. 
1888. 


1889. 


Prof. John Morris. Medal. 

Sir James Hector. Medal. 

Mr. William Pengelly. 

Mr. George Busk. Medal. 

Prof. W. Waagen. 

Prof. Edmond Hébert. 
Medal. 

Prof. H. A. Nicholson. 

Dr. Henry Woodward. 

Sir John Evans. Medal. 

Prof. F. A. von Quenstedt. 

Sir J. W. Dawson. Medal. 

Dr. Anton Fritsch. 

Mr. G. R. Vine. 

Dr. J. Lycett. Medal. 

Rey. Norman Glass. 

Prof. Charles Lapworth. 


Dr. W. B. Carpenter. Medal. 


Mr, P. H. Carpenter. 

M. Ed. Rigaux. 

Dr. Joseph Leidy. Medal. 
Prof, Charles Lapworth. 
Prof. H. G. Seeley. Medal. 
My. A. J. Jukes-Browne. 
Mr. WilliamPengelly. Medal. 
Mr. D. Mackintosh. 

Mr. Samuel Allport. Medal. 
Rev. Osmond Fisher. 

Prof. H.A. Nicholson. Medal. 
Mr. Arthur H. Foord. 

Mr. Thomas Roberts. 


Prof. W. Boyd Dawkins. 


Medal. 


1889. 
1890. 
1890. 
1891. 


1891. 
1891. 
1892. 
1892. 
1892, 
1898. 
1895. 
1893. 
1894. 
1894. 
1895. 
1895. 
1895. 
1896. 


1896. 
1896. 
1897. 
1897. 
1897. 
1898. 
1898. 
1898. 
1899. 


1899. 
1899. 


M. Louis Dollo. 

Prof.T. Rupert Jones. Medal. 

Mr. C. Davies Sherborn. 

Prof. T. McKenny Hughes. 
Medal. 

Dr. C. I. Forsyth-Major. 

Mr. G. W. Lamplugh. 

Mr. G. H. Morton. Medal. 

Dr. J. W. Gregory. 

Mr. Edwin A. Walford. 

Mr. E. T. Newton. Medal. 

Miss Catherine A. Raisin. 

Mr. Alfred N. Leeds. 


Prof. John Milne. Medal. 
Mr. William Hill. 
Rey. J. F. Blake. Medal. 


Mr. Percy F. Kendall. 

Mr. Benjamin Harrison, 

Mr. A. Smith Woodward. 
Medal. 

Dr. William F. Hume. 

Mr. Charles W. Andrews. 

Dr. George J. Hinde. Medal. 

Mr. W. J. Lewis Abbott. 

My. Joseph Lomas. 

Prof. W. Waagen. Medal. 

Mr. William H. Shrubsole. 

Mr. Henry Woods. 

Lt.-Gen. C. A. McMahon. 
Medal. 

Mr. Frederick Chapman. 

Mr. John Ward. 


Vol. 55.] 


ANNUAL REPORT. 


AWARDS OF THE BIGSBY MEDAL, 


FOUNDED BY THE LATE 


Dr. J. J. BIGSBY, F.RS., F.GS. 


To be awarded biennially ‘as an acknowledgement of eminent services in any depart- 
ment of Geology, irrespective of the receiver’s country; but he must not be 
older than 45 years at his last birthday, thus probably not too old for further 
work, and not too young to have done much.’ . 


1877. 
1879. 
1881. 
1883. 
1885. 
1887. 
1889. 


Prof. Othniel C. Marsh. 
Prof. Edward D. Cope. 
Dr. Charles Barrois. 
Dr. Henry Hicks. 

Prof. Alphonse Renard. 
Prof. Charles Lapworth. 
Mr. J. J. Harris Teall. 


1891. Dr. George M. Dawson. 

1893. Prof. W. J. Sollas. 

1895. Mr. Charles D. Walcott. 

1897. Mr. Clement Reid. 

1899. Prof. T. W. Edgeworth 
David. 


AWARDS OF THE PROCEEDS OF THE BARLOW- 
JAMESON FUND, 


ESTABLISHED UNDER THE WILL OF THE LATE 
Dr. H. C. BARLOW, F.GS. 


‘The perpetual interest to be applied every two or three years, as may be approved by 
the Council, to or for the advancement of Geological Science.’ 


1879. 
1881. 
1882. 
1884. 
1884. 
1886. 
1888. 
1890. 
1892. 


Purchase of Microscope. 
Purchase of Microscope-lamps. 
Baron C. von Ettingshausen. 
Dr. James Croll. 

Prof. Leo Lesquereux. 

Dr. H. J. Johnston-Layvis. 
Museum. 

Mr. W. Jerome Harrison. 
Prof. Charles Mayer-Eymar. 


| 1893. Purchase of Scientific In- 


struments for Capt. F. E. 
Younghusband. 

1894, Dr. Charles Davison. 

1896. Mr. Joseph Wright. 

1896 Mr. John Storrie. 

1898. Mr. Edward Greenly. 


XXXII PROCEEDINGS OF THE GEOLOGICAL society. [May 1899, 


Estimates for 


INCOME EXPECTED. 


COMPOSUGLOMS | 55 504 sors re hoe nai eave taperehe onesie aioe tle a rcleagneheve 99."8, 0 
Due for Arrears of Admission Fees .......... 69 
ANdimission ees, 1B9010% Gs re can, bien eee 240 

———— 309 6 0 
Arrears of Annual Contributions ............ 170: 0:0 


Annual Contributions, 1899, from Resident Fel- 
lows, and Non-Residents, 1859 to 1861 ....1650 


Annual Contributions in advance ............ 835 


i 
(e2) 
Or 
On 
So 
(>) 


Dividends on £2000 India 8 per cent. Stock.............. '60)"O" 70 


Dividends on £300 London, Brighton, and South Coast 
Railway 5 per cent. Consolidated Preference Stock .... 15 0 0 


Dividends on £2250 London and North-Western Railway 
A per cent. Preference Stock ...........cesnosewe dane 90 0 0 


Dividends on £2800 London and South-Western Railway 
A per cent. Prefteromee Stock aii.) iaateny « Rilo ele sisted cue 112 500 


Dividends on £2072 Midland Railway 23 per cent. Perpetual 
IPPereneneensvOc ke iirc cts acai & ake isk totena st taatereveie tens Laren 5116 0 


Sale of Quarterly Journal, including Longmans’ 
Je (Ce Oui Oi ae Pea eect trees Raa Gok baa Gia u 150 0 0 


Sale of Geological Map, including Stanford’s 
BSCCOUME He oii cele sine svele oils ite qasaoncasass. 2 0.050 


Sale of Transactions, Library Catalogue, General 
Index, Hochstetter’s ‘New Zealand,’ and List 


of Fellows ..... SES ney a ee I by OS Geo A 6 0 0 
—- 158 0 0 
2750 10 0 
DAlance BLAINSE SOCleby pa. oA cin ss akdeerercde nea ae 135 14 0 
£2886 4 0 


Note.—The following Funds are available for Extraordinary Expenditure :— 


£ 6S 
Balance in Bankers’ hands on December 81st, 1898 : 
On; Carrent Account: iccc0 sscssucoccsbaecweoes eceeeeereeee 318 Tye 
On Deposit Account oss seynn senile manneee nee eee eeeneene 750 0° @ 
Balance in Clerk’s hands on December 31st, 1898  ..........0008+ Te 


£1076 0 8 


Rol! ss. | FINANCIAL REPORT. XXxiil 


the Year 1899. 


EXPENDITURE ESTIMATED. 


Gi See uae) Ba) Oe 
House Expenditure : 
AMOS) asi. daidivsivasion anany mas eadeemenbiemientwatedeyaeece 15 0 
ire ESM a RCOF? «case oc on cones doe adeaws seaememrars 15, OF 0 
ileckeie PieWtimee ccc .cidccnensnenesas a aestaoceee 1b Oy 0 
RGIS en Suen esa stcealais ilo chi sen ae gc diye aden momeeeoe 208 “Or 0 
FG aap Satay ino om aS A eels Selah oN ate CEE Meas 25 0 0 
Horniture and. Repaitsy.....0c.cstsesaesnae! stems: 40; 30%,.0 
House-repairs and Maintenance................6 50 0 O 
pbaittal MC LEAMIN Ei. ct de encs at once am na das wedsleareas 151070 
Washing ard: Sundress... sccsnvs0ancecoccverecdeaee 30 0 0 
Mea at Wieetimeg) oo. c <ccek demos oa ctu vncseedanancn ae 20: 01, 0 
230 15 O 
Salaries and Wages, etc. : 
Apsistant SeCrehary <xs<- ssn cece eee eee 300 0 0 
Half Premium of LifeInsurance 1015 0 
Aas staat, AD CALIATY 36 33 sceanancnscveccadoaalverseen 150 0 O 
PAidh nb Olen lone u.8. see ed. suse cen. 1 Sede cas ae seeans 100 0 O 
House Porter and Upper Housemaid ......... 9P12) @ 
Winelor, HVOusemiaah 723, . Sand ron evdaccacmussessenac 4212 0 
BBHSE CUETO POM Po eas Hodes nas oc ana ae oa ee en oeenese 40 0 0 
Charwoman and Occasional Assistance......... LOMO 0 
PAGE ONMURAING HY PIER a5. ncccncndavarsccmcecs nee daducuiee 10 10 O 
755 9 O 
Pabraty (books'and Binding yo... << pemeeiewd vin teem es 250 0 0 
LL METS OTEIO Tk adi kha err ear aa ce NE sti Omen O 
Office Expenditure : 
RSPEI MON Viegas tars Sc dadaelgs eases oc anlanseeine vsownne 25, 0.20 
Niscellancous: Primtite a. ..scccse-scccconsacs canes 30 0 0 
Postage and Sundry Expenses ..............0068 90" O00 
145 0 0 
Publications : 
QaacherlyiGOunnal oo. heat aeoas acces isch cot 850 0 0 
Record of Geological Literature ............... 140 0 0 
Dist of Woellews it. .c23.32c2aen cs voes et octen nase net 3D 0 0 
Commission, Postage, and Addressing on 
SPO URE ME MELO. ek, ashe dds cx hoes bp cee SOE 100 0 O 
Abstracts, including Postage .............s.s.000- L1G: OF 0 
1235 0 0 
Estimate of Ordinary Expenditure... 3. y sisie cs «eens 0 2636 4 0 
Publication of Hutton Manuscript .......... 500) <0 
Contribution to cost of new Lavatory, etc. in 
the SOcieby se APartMem tgs ie se esac fi cgsars 200 0 0 


eae COUN 
£2886 4 0 


[The Redecoration of the Society’s Apartments is postponed 
until the alterations in Drainage, etc. have been completed, 
and will not be carried out during the current year. ] 


W. T. BLANFORD, Treasurer. 
January 20th, 1899. 


XXXIV PROCEEDINGS OF THE GEOLOGICAL society. [May 1899, 


Income and Expenditure during the 
RECEIPTS. 


To Balance in hands of Bankers on 


January nist, Leos sweden ce ee (BUS eae 
», Balancein hands of Clerk on January Ist, 
SOB AF ON are, ards wets o hate a eesa aa SIGN Xe) 

. canara (20, ao 
SMOOMPOSIPIONS EO. Cec Lie wide ck al Rode e Meee 99 8 0 
», Arrears of Admission Fees ........ LOR 2 70 
so) Admission ghees. fC. en oe ae eee keels 252 0 0 

—_—_———. 859 2 0 
,, Arrears of Annual Contributions .... 187 11 0 
», Annual Contributions of 1898, namely : 
Resident Fellows ......... GST wie 
Non-Resident Fellows... 6 6 0 
», Annual Contributions in advance .... 42 0 0 
—_——— 1866 18 0 
» Publications: 7 
Sale of Journals, Vols. 1 to 53 .........ccc00 102 ll 9 
si) JOuEMAl BVOlLL DA Mion ee eens 66 8 6 
57 th Greolo gical BN Tapia oii. cinceaaeeeastnte nas O17 88 
,, Record of Geological Literature ... JG 
») ©Dibrary @atalosue::t)...c1-c0: ces - 1 1 6 
 » eLastioteHellows f.2scc.c0.c.taisercreeee 9 0 
4 JOrmerowdsphIMdeN 5 208 cs sceachcae uaa 0 
» General Indexto Quarterly Journal 1 5 O 
air CEEAMSACLIONS \d.cchekteneesacsdaesocs ies 2138 O 
———— 182 111 
5, ancome Wax Repayment, |... ae fee eee 10 19 2 
5, Dividends (less Income Tax) on 
£2000 India 3 percent. Stock .. 58 0 0O 
£300 L. B. & 8. C. Railway 5 p. c. 
Consol. Preference Stock.. 1410 0O 
£2250 L. & N. W. Railway 4 p. c. 
Preference Stock ........ 87 0 0 
£2800 L. & 8. W. Railway 4 p. ¢. 
Preference Stock ........ 108 5 4 
£2072 Midland Railway 23 p.c. Per- 
petual PreferenceStockt.. 50 1 6 
———_—— 317 16 10 
PinterespsomdMeposibe ye usr cit ceo eye cere ae 151852 
*Due from Messrs. Longmans, in addition to the 

above.on Journal, Viol. 04 piccsesectrsosseee eo: £6412 7 
tTDue from Messrs. Stanford, on account of 

Geolosigal Wap A nccitoneecanasee sede Coemeae- nets £1 10.0 
{This Stock was converted as from April Ist, 

1898, from £1295 4 per cent. Perpetual 

Preference Stock to £2072 25 per cent. 

Perpetual Preference Stock. 

We have compared this Statement £3575 7 1 


with the Books and Accounts presented 
to us, and find them to agree. 
GEORGE J. HIND,, \ Hees 
H. BAUERMAN, j 


Vol. 55.] FINANCIAL REPORT. 


Year ended December 31st, 1898. 


PAYMENTS. 
By House Expenditure: £ 
AE ORE Ber fash cage ascleccnsteracos tee Nas Saat anamcaee tec 
Hire Wisarance’ :....25 cess -namevon saeeeerorses 15 
Milectrie Wiohting: -... 06 tese.coscssScadeasecaatees 10 
GaSe oh Soha sas Foaicus oct ecbatecweattaceeecasteaaoeaes 18 
Gels ssc socks des Retehouenesarmeerst ers oeaee 27 
Hurniture and epaits).s:.2..cdccs-stensebvesse- 43 
House-repairs and Maintenance ............... 20 
Anmunl Cleaning, 2.23 do. +n.0-cueusecssccadteouee 14 
Washing and Sundries... .0.decccsaenasacwrese dl 
Meajat Meetings” .......:.0044aetan-teedeeeeeenes 22 
», salaries and Wages: 
Assistant, SECLOLARY: 1 vac .aceseve.te dove vsaeceeedens 300 
a Half Premium of Life Insurance 10 
Assistant LAbEariam, \.05.-.sc+cees fecscndeoatt eae 150 
Aesistamts Olen Su) vase scce dednasibe xt suace meee ees 90 
House Porter and Upper Housemaid ...... 90 
Winder Housemaidl, 5. :...0..2<.dsene dine caceatos 43 
IERANGM EO? ¢.cutdece-nosseinencecigechedatvegpocs se 39 
Charwoman and Occasional Assistance ...... 10 
PICEOUIMATIES WOO accocceseencsates onnqvecete cuties 10 
Pee icea le HpelsGsrl.s cu << stemeiats gine pay se 
», Office Expenditure: 
Sia BLOMOR VR... ceca cede senc ada tseceuneee vs ceceas 25 
Miscellancous Printing ......23..0s.csc.-00c002 28 
Postage and Sundry Expenses ........ teaeeee 92 
Bo | OTE POA OEE AG NEN RR ME ENO SNe ce 
pee Wi epee fs dy aaa, Wak > an ay Mate 
,, Publications: 
Journal, Vols. 1 to 53, Commission on sale 
(L012) 1210 Aner nc - na Oe EEC I ae 8 
Journal, Vol. 54, Commission 
on’ salesthereot oy Js. .0.2 sv -c.+ss 5 8 5 
Paper, Printing, and Illus- 
GMELTOUS, Gorec. en cor cne cach hom eee 
——— 784 
Record of Geological Literature ............ 132 
nist OFM OG WwSls sa 50ce-<cccis reek +n Seats ont eiot 35 
Geological Map, Commission on sale ...... 
Postage and Addressing of Journal, etc.... 90 
Abstracts, including Postage ................ 108 


99 


99 


XXxXV 


Wo) 
HK OnIoenwpwroook 


——— _ 203 12 _ 0 


Hutton’s ‘Theory of the Earth’ (vol.iii)... 12 


Balance in Bankers’ hands on December 
31st, 1898: 


On Current Account ............... 318 
On Deposit Account ................ 750 

Balance in Clerk’s hands on December 
CHUBES ARGU Sr crete teint ore! era eRe) s 7 


W. T. BLANFORD, Treasurer. 


January 20th, 1899. 


bo 
ooooo°ooo°o 


744 11 0 
coher 10 10 90 


146 13 10 


ee 203 17 6 
Ser Le "12° 6 


On 
H= Od Co H= C9 Od Od 


— 1173 10 1 


LOG: 0). § 


£3079 T tt 


a ae 


XXXV1 


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Cor 


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XXXVI11 


FINANCIAL REPORT. 


Vol. 55.] 


‘NVWNUANVE “H 


swonpny | ; 
HaONTH “£ HOCOHD 


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o) GEsS < 868L “STE toqmodaq uo sIoyULg ev courreg “ ‘SOL GF UL yUOWYSOAUT TeyJINZ uo pueprAIq “ 
0¢ 9 POLL erent ee ggg 
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9 € 9 ‘''''* 8901 ® ¥y0019 *yU00 10d & vIpuT -UI puny uo (xB, ouoouy sey) spuopraiq “ 
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Woless.| ANNIVERSARY MEETING —WOLLASTON MEDAL. XXXIX 


AWARD OF THE WoLtAston MEDAL. 


In presenting the Wollaston Medal to Prof. Cuartus Lapworts, 
LL.D., F.R.S., the Presrpent addressed him as follows :— 


Professor LapwortH,— 


On four occasions has the Council of this Society already delighted 
to do you honour, with the Murchison Fund in 1878, with the 
Lyell Fund in 1882 and 1884, and with the Bigsby Medal in 1887. 
Our Funds are usually awarded with the desire of helping observers 
and of stimulating them to further efforts, and from this point of 
view the Funds awarded to you have certainly been most profitable 
investments. Nor could the Bigsby Medal, with its age-limit, have 
been better bestowed than on one who had done so much and such 
good work before reaching the age of 45. 

At that time, however, the effect of your work could hardly be 
appreciated to the full. I believe that the appreciation of it will 
increase as time goes on, and I am glad to know that in an elaborate 
Memoir on the Silurian Rocks of Scotland, shortly to be published, 
the officers of the Geological Survey do full justice to your series of 
papers on those rocks in the South of Scotland, saying that you 
have furnished a complete solution of the stratigraphical and pale- 
ontological difficulties of the subject, and have discovered the key to 
the complicated stratigraphy of the region. The summary, at the 
end of the Chapter on Previous Researches, is written ‘to place 
clearly on record the distinctive features of Prof. Lapworth’s 
achievements,....which resulted in establishing the true order of 
succession of the strata,’ 

We hardly know, indeed, which to admire most, the brilliance of 
your work or the single-mindedness with which it has been done; 
not only in the Scottish Uplands, but also in the still more re- 
markable region of the North-western Highlands, where the officers 
of the Geological Survey have now worked out in detail that most 
complicated structure which you so justly appreciated. 

In establishing the Ordovician System, too, you have done your 
best to promote harmony between the rival claimants for Cambrian 
and for Silurian. 

Since the Bigsby Medal was awarded to you your labours in various 
branches of Geology have been continued, notably in further working 
out the structure of the Southern Uplands of Scotland, in the 
discovery of the English Olenellus-rocks, and in additions to our 
knowledge of the Olenellus-fauna and its geological relations, Your 

VOL, LY. ' d 


xl PROCEEDINGS OF THE GEOLOGICAL society. [May 1899, 


researches on the ancient rocks of Shropshire have as yet been 
published only in abstract: the striking results at which you have 
arrived lead us to hope that ere long they may be published in 
full. 

In your address to the Geological Section of the British Asso- 
ciation in 1892, you astounded your hearers by the way in which 
you applied your knowledge of mountain-structure to questions of 
the largest kind, showing a breadth of view that had not been 
surpassed by any geologist. 

Lately, and in quite another line of work, in that admirable 
Sketch of the Geology of the Birmingham District, issued by the 
Geologists’ Association last year, you have given us one of the best 
accounts of any English district that we possess, weaving in the 
work of others and giving the whole the character of a perfect 
fabric. 

It is not only, however, for your work as a geologist that we wish 
to honour you, but also for your work as a teacher. In saying this, 
I do not refer merely to your professorial work, excellent though it 
be, but rather to that much higher teaching, one may say that 
highest of all teaching, the influence that you have had on your 
fellow-workers in Geology. That influence is to be traced in much 
of the best work that we have had of late years, and during our 
present Session we have had important papers which, I venture to 
say, would not have been written but for lines of thought suggested 
by you. 

We look forward to a long continuance of your brilliant labours, 


Prof. Lapworrs replied in the following words :— 


Mr. PRESIDENT,— 


Tam deeply grateful to the Council of the Geological Society for 
the great honour which they have conferred upon me by the award 
of the Wollaston Medal; and to you, Sir, for the kindly, and indeed 
too kindly, terms in which you have referred to my scientific work. 

It was my happy lot to have, at the very outset of my geological 
career, the aid and encouragement of a master in the science—my 
dear friend, the late Prof. Alleyne Nicholson. It has been my good 
fortune to live in districts where some new geological work could 
be done. And more, since the day when I read my first geological 
paper, I have been encouraged and stimulated by the friendship 
and the sympathy of many earnest geologists, 


Vol. 55.] ANNIVERSARY MEETING—-WOLLASTON DONATION FUND. Xxli 


When I think of my many opportunities, and remember how 
often my results have fallen sadly short of my aims, I feel that this 
distinction is less a reward than a consolation. But I accept it as an 
outward and visible sign that the Council are well aware that the 
same instinctive love for our glorious and all-embracing science as 
that which inspired those whose names adorn the illustrious roll of 
the past Wollaston Medallists has also prompted and guided me in 
my work, and has given me a place in the generous regard of the 
Fellows of the Geological Society. 


AWARD OF THE WoLLASTON DonATIon Funp. 


In handing the Balance of the Proceeds of the Wollaston Donation 
Fund (awarded to Prof. J. B. Harrison, M.A., F.G.8.) to Mr. J. J. H. 
Tratt, M.A., F.R.S., for transmission to the recipient, the PRESIDENT 
addressed him as follows :— 


Mr. Tratt,— 

I have the pleasure of handing over to you the Balance of the 
Wollaston Fund for Prof. J. B. Harrison, in acknowledgement of his 
work in the West Indies and British Guiana. In the course of the 
last 8 years he has contributed several papers to the Society (in 
conjunction with Mr. Jukes-Browne and Mr. G. F. Franks) on the 
Geology of Barbados, which have added much to our knowledge of 
old coral-reefs, of the past physical geography of the region in 
which they occur, and of the oceanic deposits with which they are 
associated. In this work, his ability as a chemist has been of great 
service. 

He has also done most of the field-work for the Geological Map 
of Barbados, and has visited other West Indian Islands and part of 
British Guiana, in order to draw up official reports on soils and gold- 
bearing rocks. In the last of these visits, made last year, he suffered 
repeated and nearly fatal attacks of fever, from which he was slowly 
recovering in December, when we last heard from him, 


Mr. Txatt replied in the following words :— 


Mr. PRresiDENT,— 

In handing this Award to me for transmission to Prof. Harrison, 
you place me in a somewhat unusual position. No communication 
has been received from Prof. Harrison since the Award was 
decided upon by the Council, We know that in December last 

a2 


xlii PROCEEDINGS OF THE GEOLOGICAL socreTy. [May 1899, 


he was recovering from an illness brought on by work in the 
interior of British Guiana, and was contemplating a journey to 
Barbados in January. The fact of our not having received any 
acknowledgement from him is, therefore, probably due to his 
absence from Georgetown. 


I need not repeat what you, Sir, have said about his scientific 
work inthe West Indies and British Guiana. He is a man who, in 
the midst of professional engagements, and without the stimulus of 
frequent, sympathetic intercourse with fellow-workers in science, 
has yet found time to carry out important scientific researches in 
far-distant British Colonies. I feel sure that he would wish me to 
express, on his behalf, the deep sense of the honour which has been 
conferred upon him, and to assure the Society that this mark of their 
appreciation will encourage him to continue his scientific work. 


[The Council have direeted the insertion in the Proceedings of 
the following letter from Prof. Harrison, which reached London 
about a fortnight after the Anniversary Meeting :— 


Government Laboratory, 
Georgetown, Demerara (British Guiana), 
February 15th, 1899. 

SIR, 

: Your letter of January 4th, 1899, only reached me on February 4th, after 
the mail had left for England. This was due to my being absent from this Colony 
in Barbados. Hence I was not able to send my thanks to the Council of the 
Geological Society, for the honour which they have conferred upon me by their 
award of the Balance of the Proceeds of the Wollaston Donation Fund, in time for 
the Anniversary Meeting on February 17th. I must ask you to express to the 
Council of the Society my keen appreciation of the honour which they have conferred 
upon me by their marked expression of approbation of the little geological work 
that I have been able to do in the West Indian Colonies, and to.assure them that the 
remembrance of it will act as an incentive to further work and as an encouragement 
during the somewhat arduous task of investigating the geological structure of the 
goldfields in the forests of the interior of this Colony. 

I purpose to expend the amount awarded to me in part payment of the cost of 
purchasing a Dick’s petrological microscope, such application of the Balance of the 
Proceeds of the Fund being, in my opinion, well suited to meet the intentions of 
the illustrious donor of the Fund. 

I have the honour to be, Sir, 
Your obedient Servant, 
J. B. HaRRIson, 
Government Analyst and Geologist, British Guiana. 
R.S. Herries, Esq., M.A., 
Secretary of the Geological Society. ] 


Vol. 55.] © ANNIVERSARY MEETING—MURCHISON MEDALS. xlili 


AWARD OF THE Murcuison Mepats. 


The Prestpunt then presented the Murchison Medal to Mr. B. N. 
Pracu, F.R.S., and another Murchison Medal to Mr. Jonnw Horne, 
F.R.S.E., addressing them as follows :— 


Mr. Pracn and Mr. Hornz,— 


Since the years 1887 and 1888, in which the Wollaston Fund 
was awarded to you successively, you have continued your work in 
Scottish Geology, taking a leading part in the latter year in that 
Report on the Recent Work of the Geological Survey in the 
North-western Highlands, printed in our Journal, in which the new 
view of the structure of that region is described in some detail. 
You have also dealt with the Olenellus-zone in the same district, 
and, ascending greatly in the geological scale, you have discussed 
Glacial geology and have undertaken cavern-research. 

Mr. Peach, moreover, has done much paleontological work, having 
long acted as Paleontologist to the Scottish Survey, and it should not 
be forgotten that he described the first fossil scorpion found in the — 
Silurian rocks of Scotland. He has also given us a paper on some 
additions to the fauna of the Olenellus-zone, and has noticed a 
radiolarian chert of Arenig age. 

Mr. Horne, either alone or in conjunction with other colleagues, 
has given us a paper on ‘ Foliated Granites and their Relations to 
the Crystalline Schists,’ showing an intimate relation between the 
two rocks and that the foliation in the former may have originated 
in at least two ways; he has communicated other papers to the 
Geological Society of Edinburgh, on igneous rocks, on voleanic necks, 
on fossiliferous Cambrian and Carboniferous rocks, and on glacia- 
tion, taking part also in the Report of the British Association 
Committee on the High-level Shell-bearing Deposits of Clava and 
Kintyre, and in the work of the Inverness Scientific Society. 

Your association together has been productive of much good work, 
and we hope that it may long continue. In handing the Proceeds of 
the Wollaston Fund to one of youin 1888, Prof. Judd remarked that 
as in your researches you had been so constantly ynited, in the re- 
cognition of your services you should not be divided, and that the 
name of Horne would appropriately follow that of Peach. On the 
present occasion, I am glad to say that we have allowed no interval 
between the names, but have, still more appropriately, I think, than 
hefore, coupled them together by awarding a Medal to each of you. 
This Award seems to me to go very naturally with that of the 


xliv PROCEEDINGS OF THE GEOLOGICAL society. [May 1899, 


Wollaston Medal to Prof. Lapworth, as you have both so largely 
helped in the detailed working-out of subjects that he brought 
before you. 


Mr. Psacu, in reply, said :— 
Mr. PRresipEnT,— 


The honour which the Council of the Geological Society have 
conferred upon me is highly prized by me, because it was by the 
advice of Sir Roderick Murchison that my thoughts were turned to 
Geology as a career in life. By means of his generosity I was able 
to avail myself of the scientific training afforded by the Royal 
School of Mines, and through his nomination I received an 
appointment on the Geological Survey. 

I ask you, Mr. President, to convey my heartfelt thanks to the 
Council for having awarded me the Murchison Medal, which, for 
me, has such tender associations. If anything could enhance the 
pleasure of this Award, it is the receiving it from the hands of one 
colleague and the sharing of it with another. 


Mr. Horys also replied, as follows :— 
Mr. Pres1DENT,— 


It is a source of great gratification to me that I have been 
deemed worthy by the Council of this Society to receive the 
Murchison Medal jointly with my old friend and colleague, Mr. 
Peach. For he gave me my early training in field-work, and to 
his range of knowledge and ample experience I have owed much 
during my Survey career. 

It is likewise a special pleasure to be linked with the great 
founder of this Medal, whose name is so closely associated with the 
history of Scottish Geology. While preserving a feeling of loyalty 
to our former chief and his successors in office, we have at the same 
time tried to exercise independence of judgment in dealing with 
Scottish geological questions. In doing so, we have realized, 
perhaps more vividly than others, the permanent value and brilliant 
power of Prof. Lapworth’s researches in Scotland, whose reception 
at this anniversary of the highest honour which the Council can 
bestow is a great pleasure to us. Regarding the Geology of the 
North-western Highlands, we feel that our colleagues who have 
worked with us in that complicated region justly share in the honour 
which has been conferred upon us. 


Vol. 55.] ANNIVERSARY MEETING—MURCHISON GEOLOGICAL FUND. Xxlv 


AWARD OF THE Murcuison GEoLocicaL FUND. 


In handing the Balance of the Proceeds of the Murchison Geo- 
logical Fund (awarded to Mr. James Bennie, of the Geological 
Survey of Scotland) to Sir A. Germis, D.Sc., F.R.S., for trans- 
mission to the recipient, the Presmrent addressed him in the 
following words :— 


Sir ARCHIBALD GEIKIE,— 


In handing over to you the Balance of the Proceeds of the 
Murchison Fund for Mr. Bennie, I have the pleasure of doing 
honour to one who has supplemented his work for the Geological 
Survey by other labours, 

He began geological observations in 1850, while employed in a 
Glasgow warehouse, by collecting fossils from the Lower Carbo- 
niferous rocks of the neighbourhood, and he also examined the 
Glacial deposits, communicating his results to the Geological Society 
of Glasgow. 

He joined the Survey, as Fossil-Collector, in 1868, and held that 
post until lately, when he had to retire on account of age. 

In 1873 he first discovered Holothuride in Scottish Carboniferous 
rocks. He found new species of Blastoidea (described by Mr. 
R. Etheridge, Jun., and Mr. Carpenter) and also Brachiopoda ad- 
hering to Crinoid-stems (producing pathological modifications of the 
latter). He assisted the late H.B. Brady with specimens of Car- 
boniferous Foraminifera, for his Monograph ; wrote a paper, jointly 
with Mr. Kidston, for the Royal Physical Society of Edinburgh, 
‘On the Occurrence of Spores in the Carboniferous Formation of 
Scotland’; and, more lately, worked with great success in the 
collection of Arctic plants from deposits of Glacial age. 

We hope that he may still be able to continue his useful labours. 


-_— 


Sir A. Gerxie replied as follows :— 
Mr. PRresrDENT,— 


Mr. Bennie has commissioned me, on his behalf, to receive this 
Award, and to express to the Council his grateful thanks for the 
honour that they have conferred upon him. His long life has 
been enthusiastically devoted to geological pursuits. Before he 
joined the Geological Survey, the scanty intervals of leisure which 
he could snatch from the daily toil of his avocation were given 


xlvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


up to the search for fossils among the Carboniferous and Pleistocene 
deposits around Glasgow. When he became Fossil-Collector to 
the Survey he was enabled to pursue, as his regular and ordinary 
employment, what had before been the occupation of his brief. 
hours of recreation. And now, having passed the age-limit of 
the Civil Service, and having retired on a small pension, he con- 
tinues to work on in his old way, and appears daily still in his 
accustomed place in the Survey Office, busy with the search for 
micro-organisms among the silt and peat which he gathers from 
some of the floors of vanished Arctic lakes around Edinburgh. ‘The 
stores of knowledge which he has slowly amassed have always been 
at the disposal of others who could make good use of them. That 
his quiet, unobtrusive labours should have attracted the notice and 
received the approbation of the Council of the Geological Society 
is to him a source of deep gratification. So long as life and strength 
remain, he will continue the work which has been the chief 
pleasure and solace of his career. 


AWARD oF THE LyEtt MEDAL. : 


The PresipEent then presented the Lyell Medal to Lieut.-Gen. C. 
A. McManon, F.R.S., addressing him as follows :— 


General McManon,— 


Besides your petrological work in India you succeeded, by work in 
the field as well as with the microscope, in tracing out the relations 
of the gneissose granite or central gneiss of the Western Himalayas, 
and in proving its intrusive character as well as its Tertiary age. 
You thereby threw much light on the theory of the origin of that 
great range, to a knowledge of the Glacial geology of which you 
have also contributed. 

Returning to this country, you have given our Society several 
papers, chiefly on the rocks of Cornwall and of Devon. In these 
you have contended that the serpentine of the Lizard district is 
intrusive, that the banded structure of the accompanying gabbros is 
due to fluxional movements, and that the granite of Dartmoor is 
an intrusive igneous rock of the usual character. These papers and 
various communications to the ‘ Geological Magazine’ show that, 
besides being a skilled observer, you have the valuable adjunct of 


Vol. 55. ] ANNIVERSARY MEETING—-LYELL MEDAL. xlvii 


eritical ability, combined, I need hardly say, with all courtesy. 
Kindred Societies, too, have had the benefit of your work, in the 
microchemical examination of minerals among other things. Nor 
has your Indian experience remained unused. 

Labouring under the disadvantage of taking to the study of 
Geology comparatively late in life, you have attacked it with the 
energy of a British soldier, and have fought your way into the 
foremost ranks of our petrologists. 


Lieut.-Gen. McManon, in reply, said :— 
Mr. PrestpENT,— 


I feel deeply the honour conferred upon me by the Council of the 
Geological Society in awarding to me the Lyell Medal, as a recogni- 
tion of my humble efforts to advance the cause of Geological Science. 
The pleasure which this has given me is greatly enhanced by the 
kindly and flattering way in which you have spoken of my work, 
and by the sympathy accorded to me on this occasion by the 
Fellows of the Society. . 

It is very gratifying for an amateur to have his work stamped 
with the hall-mark by specialists who have made Geology the study 
of their lives. I have always received help and encouragement 
from professional geologists, and had it not been for the generous 
aid which they have invariably been ready to afford, I should not this 
day have been a recipient of the Lyell Medal. 


AWARD oF THE LyELt GeoLogicaL Funp. 


In handing to Mr. Freprericx Coapman, A.L.S., F.R.M.S., a moiety 
of the Balance of the Proceeds of the Lyell Geological Fund, the 
PresipEnT addressed him in the following words :— 


Mr. CHapman,— 


You have been an enthusiastic worker with the microscope for 
many years, and half of the Balance of the Lyell Fund has been 
awarded to you as a mark of our regard for what you have done 
for the fossil Foraminifera and other Microzoa, much of your work 
being published by the Royal Microscopical Society. 

Your earlier papers, written in conjunction with Mr. Sherborn, 


xlviii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899 


were based on the London Clay of our immediate neighbourhood, 
and then on that of Sheppey. 

You have also dealt with the Foraminifera of the Gault, writing 
a set of ten papers specially on the Gault of Folkestone (1891-98). 
The microscopic fauna of the Phosphatic Chalk, of the marl and 
silts of Barry Docks, and of Barbados deposits have been described 
by you in our Journal, and you have also given us an elaborate 
paper on the Bargate Beds and their Microscopic Contents (1894). 
Rheetic Foraminifera you have described in the ‘ Annals & Magazine 
of Natural History,’ Pleistocene Ostracoda and Jurassic Microzoa 
in the Proceedings of the Geologists’ Association, nor have you 
neglected recent Foraminifera. 

That you should have so well used the opportunities which you 
have had while serving under Prof. Judd is a source of satisfaction 
to us, and we hope that this Award may be an encouragement to 
you in further researches. 


Mr. Cuapmay, in reply, said :— 
Mr. PresipEnt,— 


I desire to express my sincere thanks to the Council of this 
Society for selecting me as one of the recipients of the Lyell 
Award, and to you, Sir, for the very encouraging words with which 
you have honoured me. 

However little my work in the past may have merited this dis- 
tinction, I trust that, with further opportunities, my later endeavours 
in Micropaleontology and other branches of microscopical work will 
in some degree justify this selection. 

I cannot let this occasion pass, without saying how much direct 
help and advantage I have derived from the methods of geological 
research carried out in Prof. Judd’s laboratory at the Royal 
College of Science. 

Nor would I forget the invaluable advantages which I have derived 
from the friendship of those engaged in the same line of research, 
and especially are my obligations due to Prof. T. Rupert Jones and 
Mr. C. Davies Sherborn. 


The Presrpenr then handed the other moiety of the Balance of 
the Proceeds of the Lyell Geological Fund to Mr. Jonn Wann, F.G.S., 
addressing him as follows :— 


Vol. 55.] | ANNIVERSARY MEETING—LYELL GEOLOGICAL FUND. Xlix 
Mr. Warp,— 


One half of the Balance of the Lyell Fund has been awarded 
to you, in recognition of your long services to the Geology of 
your district. You have devoted many years to the study of the 
Geology of North Staffordshire, making a large collection of fossils, 
especially Vertebrata, from the Coal Measures, including many new 
forms, and thus aiding, with material, the researches of various 
paleontologists, including Sir Philip Egerton, Prof. Huxley, and 
Dr. Traquair. 

For nearly 40 years you have contributed valuable papers to 
local societies and to mining institutes, among which is a detailed 
essay on the Geological Features of the North Staffordshire Coal- 
field and its Organic Contents. You were indeed the first to 
record a rich marine fauna in certain Coal-Measure horizons in 
North Staffordshire. 

Your detailed and accurate knowledge of the district has always 
been freely placed at the service of other observers. 


Mr. Warp, in reply, said :— 
Mr. PREsIDENT,— 


It is difficult for me adequately to express my appreciation of 
the high honour conferred by the Council of the Geological Society 
in awarding to me a moiety of the Balance of the Lyell Fund; 
and to yourself, Sir, my best thanks are due for the complimentary 
terms with which you have supplemented it. 

Forty years and upwards have now passed away since I was first 
led by the inspiring influence of an old and much revered friend, the 
late Dr. Garner, author of the ‘ Natural History of the County of 
Stafford,’ to devote my leisure hours to the investigation of the 
fossil fauna and flora of the North Staffordshire Coalfield. From 
that time until the present I have never missed an opportunity for 
research. 

It has been my good fortune to labour in a field of science which, 
although local, is one that affords abundant facilities for research 
in Carboniferous Paleontology, and to have been led to the investi- 
gation of a branch of our science which had previously been much 
neglected. 

My attention has principally been directed to one special line 
of research—the Fossil Vertebrata, of which class I have collected 


] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


between 3000 and 4000 specimens of Fossil Fishes and Reptilian 
remains. Of the former, about 40 genera and species are new to 
science, in addition to many rare and unique examples. Within 
the past few years, the principal portion of my collection has been 
added to the National Collections in Cromwell Road, while another 
portion enriches the geological collection in the Edinburgh Museum. 

I avail myself of the present opportunity to acknowledge my 
gratitude to the many eminent paleontologists, to whose generous 
assistance and encouragement I owe so much of my success. To 
Dr. Traquair my thanks are specially due, for the valuable assist- 
ance and friendly aid accorded to me during the past 18 or 20 
years. Not only has he assisted in naming specimens, but he has 
contributed to science a number of papers and separate monographs 
devoted to the elucidation of the structure and affinities of new 
and rare genera and species of Fossil Fishes from my collection. 

I shall look upon the Award not only as bearing the stamp of 
approval and generous recognition of the Council of the Society for 
my past services to Palzontological Science, but also as an addi- 
tional incentive to me to continue with renewed energy those 
researches the pursuit of which has been to me a labour of love 
for so many years. It will be not only my aim, but my highest 
ambition, in the time that yet remains to me, to contribute to our 
common science results that will be of greater scientific value than 
anything that I have hitherto been able to offer, and to render myself 
more worthy of the distinction which has been conferred upon me. 


AWARD OF THE Bicsspy MEDAL. 


In handing the Bigsby Medal (awarded to Prof. T. W. Enez- 
wortH Davin, B.A., F.G.S.) to Prof. J. W. Jupp, C.B., LL.D., 
F.R.S., for transmission to the recipient, the Presipenr addressed 
him in the following words :— 


Professor J upD,— 


As, after studying under Sir Joseph Prestwich at Oxford, Prof. 
David had the advantage of attending your courses at the Royal 
College of Science, it is fitting that you should receive the Bigsby 
Medal for him. 


Vol. 55.| ANNIVERSARY MEETING—BIGSBY MEDAL. hi 


After having engaged in an investigation of the Glacial pheno- 
mena of his native district, South Wales, the results of which were 
published in our Journal and reprinted by the Cardiff Naturalists’ 
Society, Prof. David was appointed to the Geological Survey of 
New South Wales, and during his 9 years’ service thereon many 
reports and maps, as well as independent papers on various branches 
of our science, show his devotion to his work. 

In 1891, having been made Professor of Geology in the University 
of Sydney, he threw himself with energy into the work of teaching. 

Among the series of scientific communications from his pen, two 
must be specially remembered by many of us, namely, his paper on 
Evidences of Glacial Action in Australia in Permo-Carboniferous 
Time, ably delivered by himself in this room in 1896, and generally 
thought to be the most convincing on the subject, and lately the 
equally important paper (written jointly with Mr. E. F. Pittman) 
on the Radiolarian Cherts of New South Wales, read, in the 
authors’ absence, by Dr. G. J. Hinde. 

Besides so much good work in his own Colony, Prof. David has 
greatly assisted in the investigation of the Coral-atoll of Funafuti, 
and it is to his energy and perseverance that the success of this 
undertaking is largely due. 

The Council of the Geological Society do not forget our Colonial 
brethren, but delight to honour those who, like Prof. David, do good 

work in our far-off lands. 


Prof. Jupp, in reply, said :— 
Mr. PREsiDENT,— 


On behalf of my friend, Prof. Edgeworth David, I thank you 
for the kindly terms in which you have spoken of his work. Part 
of that work is known to all Fellows of this Society, by the papers 
which Prof. David has contributed to our Journal. But another, 
and very large part, is the record of geological studies carried on 
during the last 20 years in his adopted country—the great Colony 
of New South Wales. There is, however, one labour of his, which 
I believe will prove to be of especial importance in advancing 
Geological Science. I refer to what he has done in connexion with 
the boring of a Coral-atoll in the Pacific Ocean. Three expeditions 
in successive years have resulted in the carrying down of the boring 
at Funafuti to the depth of 1114 feet. The leader of the first 
expedition—Prof. Sollas—assures me that he owed much to the aid 


hi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


and goodwill of Prof. David in starting this important enterprise. 
In the second expedition, Prof. David, with his accomplished and 
energetic wife, went out to Funafuti, and they were largely instru- 
mental in overcoming the serious difficulties of the work. The third 
expedition, in which the triumph of the investigation was finally 
assured, would probably never have been set on foot but for 
Prof. David’s indomitable perseverance, and for the tact and the 
influence which he brought to bear on all who could aid in this 
important undertaking. ‘The last portion of the core obtained by 
the Funafuti boring will probably be in this country within a few 
days, and, from what I have seen of the other parts of the core, I am 
convinced that its study by zoologists, botanists, and chemists will 
result in new information being obtained concerning the origin of 
coral-reefs—information which will prove of inestimable value to 
the Geologist. 


[ The Council have directed the insertion in the Proceedings of 
the following letter from Prof. David, which reached London about 
a month after the Anniversary Meeting :— 


The University of Sydney (New South Wales), 
February 13th, 1899, 

GENTLEMEN, 

The announcement of the Award to me by you of the Bigsby Medal has 
just come as a very pleasant surprise. I am deeply grateful to you for the honour 
which you have done me, for I deem it a very great honour to receive from such a 
body so handsome a recognition of my efforts as a field-geologist. 

One of the branches of my geological research specially referred to by you, in 
connexion with this Award, is that of Glacial Action in Australia in Permo-Carboni- 
ferous Time. In my capacity as Secretary of the Glacial Committee of the Australasian 
Association for the Advancement of Science exceptional facilities have been afforded 
to me for collecting and reviewing glacial evidences; and any further addition to our 
knowledge of these evidences which I may have been able to make, has been largely 
due to the help of my colleagues on the Glacial Committee, and to the sympathetic 
assistane2 of the Association. 

The excellent reception accorded by the Geological Society to my Glacial paper in 
1897 has already proved a great encouragement to me; and now the Award of the 
Bigsby Medal invigorates me for fresh work, and more than ever strengthens me in 
the resolve to try to show myself in the future not unworthy of your high trust, or 
of this handsome gift. 

Believe me, Gentlemen, 
Yours faithfully, 
T, W. EpGEWwortH Davip. 

The Council 

of the Geological Society of London. ] 


Vol. 55. | ANNIVERSARY ADDRESS OF THE PRESIDENT. hii 


THE ANNIVERSARY ADDRESS OF THE PRESIDENT, 
Witttam Wartaxer, B.A., F.R.S. 


Having fulfilled the pleasant part of my duties, I have now to 
enter on the sad part, to note our losses during the past year. In 
this, precedence will be given to Foreign Members and Correspondents, 
of whom we have lost six. 


WitHetm Barnim Dames was born in 1843, and was educated 
at the University of Breslau, where he took his doctor’s degree 
with a thesis on the Devonian Beds of Freiburg, in Lower Silesia. 
He then went to the University of Berlin, where he worked to the 
end of his life, becoming Professor of Geology and Paleontology. 

His chief work was paleontological, on Echinoidea, Crustacea, and 
more particularly Vertebrata, on all of which he did valuable work 
relating to various formations. To him we are largely indebted for 
a knowledge of that remarkable fossil the Archwopteryw. 

He investigated the Silurian strata of Gothland for the purpose of 
establishing the source of the Silurian rocks in the gravels of the 
North German plain, a subject on which he did much work. 

Since 1885 he had been one of the editors of the Neues Jahrbuch. 
He was elected a Foreign Correspondent of this Society in 1891, and 
a Foreign Member in 1895. He died on December 22nd, 1898.! 


Car. W1LHELM, Ritter von GuMBEL, was born on February 11th, 
1823, at Dannenfels, in the Bavarian Rhenish Palatinate, and was 
the youngest of nine brothers. 

He published his first paper, ‘Geognostic Observations on the 
Donnersberg,’ in 1846, and this attracted the attention of Von 
Dechen, who thereafter always remained his friend. 

In 1848 he passed with distinction the State mining examination 
at Munich, and began practical work at the Colliery of St. Ingbert. 
Soon after he found employment in that district as surveyor, and 
then came the turning-point in his career. The Bavarian authorities 
agreed to start a Geological Survey, and in 1851 Gumbel was called 
to Munich to take part therein as chief geologist. 

He carried out, almost single-handed, the survey of the Bavarian 
Alps, publishing the results in 1861, in a large volume, with 
maps. Meanwhile he had obtained his doctor’s degree, and, in 
1863, was made Honorary Professor of Geognosy and Surveying at 
the University, while in 1868 he was entrusted with the lectures 


1 See also the notice by H. Tietze, Verh. k.-k. geol, Reichsanst. 1898, 
pp. 408-410, 


liv PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


on geognosy and geology at the Polytechnic School and with the 
management of the mineralogical collection. 

In 1869 he became a Member of the Royal Bavarian Academy. 
A reorganization of the mining administration took place in that 
year, and the Geological Survey, under him, was brought into that 
department, the rank of Oberbergrath being conferred upon him at 
the same time. Ten years later he was made chief of the whole 
department, as Oberbergdirector, an office which he held to the 
last, or for nearly 20 years. 

At the beginning of 1897, when he was suffering from the illness 
which proved ultimately fatal, the rank of Privy Councillor was 
accorded to him. He was alsoa Member of many learned societies, 
and of various Orders of knighthood. Moreover, on account of his 
great services in the matter of water-supply, the City of Munich 
conferred upon him the distinction of honorary citizenship. 

He was elected a Foreign Correspondent of this Society in 1863, 
and a Foreign Member in 1877. 

His chief official work is the geological description of Bavaria, in 
four large volumes ; eighteen sheets of the map have also been issued. 
But he has also published some six score memoirs, papers, etc., 
several of the size of books, and treating of all branches of geological 
science, his paleontological work being concerned more especially 
with the smallest forms. 

He often directed his knowledge to the solution of practical 
problems, and in mining matters folk turned to him as the most 
trustworthy authority. 

He died, it may be said, in harness on June 18th, 1898, and his 
body was cremated, according to his wish.’ 


By the death of Jamzs Hart on August 7th, 1898, we lost our 
senior Foreign Member and our senior Wollaston Medallist, for he 
was elected so long ago as 1848, and received the medal (with H. von 
Meyer) in 1858 together with the Proceeds of the fund. 

He was born at Hingham (Mass.) on September 12th, 1811, and 
educated at the Rensselaer Polytechnic Institute at Troy, in the State 
of New York, graduating in 1832, and then serving as Professor of 
Chemistry and Natural Science, and afterwards of Geology. 

Hall joined the Geological Survey of the State of New York in 1836, 
and remained on it till the day of his death, a continuous service of 

1 The above notice is summarized from a full account of his life in the 


Bericht. d.k. Techn. Hochschule, Munich, for 1897-98. There is another 
account, with a bibliographical list, in the Verh. k.-k. geol. Reichsanst. 1898, 


pp. 261-268. 


Vol. 55. | ANNIVERSARY ADDRESS OF THE PRESIDENT. ly 


62 years. At first he seemed more interested in stratigraphical work; 
but in 1843 he was made State Paleontologist, and as such wrote 
or edited thirteen large quarto volumes on the paleontology of the 
State from 1847 to 1894, besides many memoirs and papers in 
the Annual Reports of the State Museum and in the Reports of the 
State Geologist. He also wrote much for various learned societies 
and scientific journals. 

In 1855 he became State Geologist of Iowa, and in 1857 of 
Wisconsin, in the Reports of which Surveys, as well as in those of 
other States, he made many additions to American Paleontology, 
as also in the Reports of various Expeditions or Commissions. The 
Canadian Geological Survey also profited by his help in the descrip- 
tion of Graptolites. 

His descriptions of Palzeozoic invertebrata have been the founda- 
tion for like work in other States and by other observers; and his 
correlation of the Paleozoic formations of New York with those of 
the Mississippi Valley and of Europe is of great importance. 

He also took up broad questions of stratigraphical geology, and 
was the first to note the connexion of the elevation of mountain- 
chains with previous subsidence and accumulation of sedimentary 
deposits. 

Hall was President of the American Association for the Advance- 
ment of Science at the Montreal Meeting in 1857, and first President 
of the Geological Society of America in 1859. In 1842 he became 
M.A. of Union College, in 1862 LL.D. of Hamilton University 
(Canada), and in 1884 received the same honour from McGill 
University, Montreal. Notwithstanding his great age (then 
nearly 86), he took part in 1897 in the Excursion of the International 
Geological Congress to the Ural Mountains, and he continued 
his paleeontological work to the last. 

The foregoing particulars are taken chiefly from notices of his career 
in an English and in an American journal,’ from the latter of which 
we may quote the following remarks, partly as illustrating the 
political difficulties that sometimes beset the official man of science 
in the United States, difficulties from which we are happily 
free in this country:—‘ Extreme longevity combined with per- 
sistent continuity of purpose, and the vast resources of the State of 
New York, must be accounted as a leading factor in any considera- 
tion of the scientific monument which this man erected for himself, 
and for which, in addition to personal work, contributions were 

' Geol. Mag. 1898, pp. 431, 432; Amer. Journ. Sci. ser. 4, vol. vi (1898) 
pp. 487, 438. 

VOL. Ly. é 


lvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


levied from among several generations of assistant co-workers. 
The magnitude of the private and public collections accumulated at 
Albany, the large sums spent for their investigation, and the 
elaborate publication of results, together with the amount and 
variety of the investigations carried on, attracted the rising and 
ambitious paleontologists of the United States to Albany for many 
years. This enabled the State Geologist to equip himself with some 
of the best talent in the country, and in a considerable degree 
determined the quantity and character of the output of his depart- 
ment.... Asa lobbyist among over sixty annual legislatures he 
held an unique position in the State. In his successful adjustments 
to the kaleidoscopic and bewildering political complexion of this 
long period is shown his wealth of resource and adaptability. 
In his managerial skill and tireless energy he was alone and 
without a peer.’ ) 
[Since this notice was written a long account of ‘The Life & 
Work of James Hall” by H.C. Hovey, has appeared,! with Lists 
of his Titles and Memberships and of his Published Works, which 
number 42 books and 260 papers, ranging in date from 1836 to 
two ‘in the press.’ Of course, many of these were joint work. | 


Jutes Marcov was born at Salins, in the French Jura, on April 
20th, 1824, and worked with J. Thurmann on the geology of 
the Jura Mountains. He acted as travelling geologist for the 
Jardin des Plantes, of Paris, visiting North America in 1847, and 
accompanying Agassiz to the Lake Superior district in the following 
year. Later on he studied the geology of New Jersey, of Pennsyl- 
vania, and of Virginia. He made a short visit to Europe in 1850, 
but then returned to America, and published his geological map of 
the United States and the British possessions in North America. 

He entered the geological service of the United States in 1853, 
but was forced by ill bealth to return to Europe in 1855, from 
which year to 1859 he held a Professorship in the Polytechnic 
School at Ztrich. In 1861 he again went to the United States, 
and helped Agassiz in founding the Museum of Comparative Zoology, 
taking charge of the paleontological division. In 1875 he re-entered 
the national service for a time. 

Among his many publications should be noticed a geological 
map of the world. 

Of late years, his papers were mostly of a controversial nature ; 


1 Amer. Geol. vol. xxiii (1899) pp. 187-168 & pls. iv, v (portraits). 


Voll 55. ANNIVERSARY ADDRESS OF THE PRESIDENT. lvil 


indeed, he was a master of controversy, especially in relation 
to the Taconic rocks. 

In 1867 he received the Cross of the Legion of Honour. In 1875 
he was elected a Foreign Correspondent of our Society, and in 1879 
a Foreign Member. He was also a member of many American and 
Kuropean Societies. He died at his home in Cambridge (Mass. ) 
on April 18th, 1898.’ 


FripoLin von SANDBERGER was born on November 22nd, 1826, 
at Dillenburg (Nassau), and was educated at the Universities 
of Bonn, Heidelberg, and Giessen, at the last of which he took the 
degree of Ph.D. He afterwards went tothe University of Marburg, 
where he prepared his first great paper, on the Geological Relations 
of Nassau, published in 1847. 

In 1849 he entered the State service of Nassau as Inspector of 
the Natural History Museum at Wiesbaden, a post which he held 
for 6 years, during which time he published two important works, 
‘Researches on the Tertiary Basin of Mayeice’ and ‘ The Fossils of 
the Rhenish Group in Nassau.’ 

In 1855 he went to Karlsruhe as Professor of Mineralogy and 
Geology at the Polytechniknum, and he worked there for nearly 
9 years. SBesides his professorial duties, he took part in the Geo- 
logical Survey of Baden, and continued his studies on the Mayence 
Basin. 

From 1863 to 1896 he was Professor of Mineralogy and Geology 
at the University of Wurzburg, a post which he resigned on the 
occasion of the jubilee of his doctorate. At Wirzburg he studied in 
detail the Trias of the neighbourhood, and, later on, that of the Main 
district and of Lower Franconia. He also continued his palaonto- 
logical labours, and published the results in his great work, ‘The 
Land and Freshwater Shells of the Ancient World’ (1871-76). 
In later years he also took up chemico-geological work, especially 
in regard to the formation of veins, and published the results in his 
‘Researches on Metalliferous Veins’ (1882-85). 

He was a Member of the Royal Bavarian Academy and a Privy 
Councillor. He received the Wollaston Fund in 1855 (with 
Dr. G. Sandberger), was elected a Foreign Correspondent of this 
Society in 1863, and a Foreign Member in 1875.? 

1 See also Amer. Journ. Sci, ser. 4, vol. v (1898) p. 398, from which these 
remarks are chiefly taken. 

2 The above notice is almost wholly summarized from an account of his life 
in Verh. k.-k. geol, Reichsanst. 1898, pp. 199-200. 

ée2 


lviii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


AtpeHonse Briart was for the fifth time President of the Geo- 
logical Society of Belgium (Liége) at the time of his death, on 
March 15th, 1898, in the 74th year of his age, at Morlanwelz. 

His name was for some time associated with that of Cornet, 
who died before him, the two observers doing much work on Belgian 
geology—Tertiary, Cretaceous, and Paleozoic, including a geological 
map of the central part of Hainault, in thirty sheets. 

M. Briart read several papers on geology before the Belgian 
Academy and the Geological Society of Belgium. He was chief 
engineer of the Mariemont and Bascoup Collieries. 

He was elected a Foreign Correspondent of this Society in 1884. 

A funeral discourse, by Prof. Dewalque, is printed in the Annales. 
de la Socicté géologique de Belgique, vol. xxv (1898) pp. lii—lviii. 


By the death, last July, of Witxt1am Guyzon Aruerstons, M.D.,. 
we have lost our oldest South African geologist. 

He settled in medical practice at Grahamstown in early life, 
and in 1839 becoming interested in local geology, he took up the 
subject thoroughly after seeing Mr. A. G. Bain’s reptilian fossils. 
Mr. Bain has said of him, ‘from that day an intimacy began 
between us, which soon ripened into friendship,’ and he speaks of 
‘the transcendent talents of Dr. Atherstone, which soon imbued our 
minds with elevated ideas, and gave fresh vigour and stimulus to 
our pursuits.’ 

Dr. Atherstone started a Geological Society at Grahamstown, 
which city has been called the birthplace of South African Geology, 
helped in the establishment and progress of the Albany Natural 
History Museum, and became a Fellow of our Society in 1864. 

He went on various expeditions, in one with’ Bain, in another 
with Rubidge, accounts of which have been published. Some were 
for geological investigation, one to examine copper-bearing rocks: 
in Namaqualand, and another to examine caves. He gave many 
fine reptilian fossils to the British Museum (Natural History). 

Through him the occurrence of the diamond at De Kalk was 
brought to light in 1867, and to this is owing to a large extent the 
great diamond-working in South Africa. Later on, he visited the 
diamond-mines and wrote many notes to local publications on 
matters connected therewith.' 


1 This account has been condensed from a notice by Prof. T. R. Jones, 
‘Nat. Sci.’ vol. xiv (1898) pp. 73-74. - 


Vol. 55.] ANNIVERSARY ADDRESS OF THE PRESIDENT. lix 


Metvitte Arrwoop was born at Prescott Hall, Old Swinford 
(Worcestershire) on July 31st, 1812. 

When quite a young man he went to the gold- and diamond-fields 
of Brazil for some years, returning to England in 1839, and then 
worked the Old Ecton Copper Mine, in Derbyshire. 

The health of his wife, a sister of Edward and David Forbes, 
led him to leave England in 1852, when he went to California and 
became manager of the Agua Fria Gold-quartz Company; and for the 
rest of his life he applied his knowledge to mining and metallurgical 
work, devoting his spare time to microscopical investigations and 
making a valuable collection of minerals and rock-sections. 

He was elected a Fellow of this Society in 1876, and in the 
following year he was one of nine men who organized the California 
State Geological Society. He was also a member of the California 
Academy of Sciences and of the San Francisco Microscopical Society, 
and he contributed many papers to the Transactions of those 
Societies. 

He died at Berkeley, near San Francisco, on April 23rd, 1898.1 


Dueatp Bett, who was born in the Upper Ward of Lanarkshire 
in 1827, was elected a Fellow only in 1892. He passed his child- 
hood and school-life in the Vale of Leven, and at a comparatively 
early age began work in the office of the Dalmonach Printworkg 
there, being transferred to the town-office, in Glasgow, after some 
years. He subsequently became confidential clerk to Mr. J. N, 
Fleming, and, on the suspension of business by his employer, ceased 
work for a time, and then became cashier to Messrs. L. & W. 
Campbell & Co., a post which he held until the failure of his health 
in 1896. 

He joined the Geological Society of Glasgow in 1860, and his first 
printed paper was read 10 years afterwards. It was on Glacial 
Geology and in favour of Boulder Clay having originated from land- 
ice, but allowing a period of depression, in which latter he ceased 
to believe later on. From this time onward he took a leading part 
in Glacial geology, both by papers and in discussions before the 
Glasgow Geological Society, and he published a book, ‘ Among the 
Rocks round Glasgow,’ which was based on excursions made by 
members of that Society. He was one of the most strenuous 
supporters of the land-ice theory. 


1 The above notice has been condensed from a published obituary by Mr. G, 
Attwood in Geol. Mag. 1898, pp. 335-336, and from a MS. obituary kindly sent 
by Mr. H. G. Hanks, of San Francisco. 


Is PROCEEDINGS OF THE GHOLOGICAL SOCIETY. [May 1899, 


He also took part in the meetings of the British Association as 
far as he could, and bore the chief share in the work of the 
Committee for the Investigation of the High-level Shell-bearing 
Deposits of Kintyre, etc., of which he was secretary. 

He wrote several papers and notes that have appeared in the 
Geological Magazine of late years, and a paper for our Society 
in 1895. 

Towards the end of 1896 he was compelled to give up work; his 
illness increased, and he became physically helpless for six months. 
before his death on January 15th, 1898, although he retained his 
mental faculties until a few days before the end.? 


JoHN ALLEYNE BoswortH was a mining-engineer, and carried out 
several borings in Leicestershire and Shropshire, as well as the first 
part of the boring for the Sub-Wealden Exploration Committee. 
He was elected a Fellow of this Society in 1870, and died on July 
30th, 1897, from an accident which happened two days before: 
when he was watching some men in a brick-pit, he lost his footing, 
and fell a distance of 20 feet. 

His death appears to have escaped notice last year. 


I have now the sad duty of announcing the decease of one with 
whom I had been on terms of intimate friendship for many years, 
and whose kindness and genial companionship I shall ever remember. 

Wittram Cortcusster was born on July 21st, 1813, at Sutton, near 
Woodbridge, and much of his life was spent in Suffolk or in the 
bordering part of Essex. For a great many years he lived in or near 
Ipswich, and in his later years at Burwell, in Cambridgeshire. 

He was educated at University College, London, where he wag 
the fellow-student of Prestwich, and the two were life-long friends. 
Intending to follow the profession of an architect, he travelled much 
in Italy; but he turned to commercial pursuits, which in two 
cases were of a kind in which geology is concerned. 

He engaged in the raising of cement-stone from the London Clay 
of the coast near Harwich, for the manufacture of Roman cement, 
until that work was stopped, on account, I believe, of the damage 
resulting to the land. Iam informed that the vessels used, and 
now turned into shrimpers, are still known as ‘Colchester’s fleet.” 
He also became the pioneer in the working of our various deposits 
of phosphate of lime, especially from the Crag of Suffolk and from 
the base of the Chalk in Cambridgeshire. The Suffolk industry is 


1 The above notice has been chiefly taken from a MS, obituary by Mr. J. B. 
Murdoch, which, I am informed, will be published in Trans. Geol. Soc. Glasgow.. 


Vol. 55.] ANNIVERSARY ADDRESS OF THE PRESIDENT. ie 


now a thing of the past, and that of Cambridgeshire nearly so ; 
indeed in the latter county there is but one man raising coprolites, 
and that is Mr. Edward Colchester, the eldest surviving son of my 
old friend. 

He was elected a Fellow of this Society in 1857, and in him we 
lose one of the few links between the geologists of what we may 
term the ‘earlier Lyellian age’ and those of the present. A great 
reader, he was not an author, though one of the best letter-writers 
that I have known; but he helped greatly in furnishing texts 
for others to write on, by the careful collection of specimens from 
the works with which he was connected, and to him we owe the 
fossil, known ati first as the Macacus eocenus, and the Didelphis that 
‘ bears his name. Many of his best specimens he gave to the fine 
museum at Ipswich, to which he was one of the original subscribers, 
when it depended on subscriptions. Other collections, too, have 
benefited by his generosity, and indeed he was always ready to 
help geologists by all means in his power. 

In later life he busied himself in collecting flint-implements in 
his neighbourhood, and obtained a goodly number of these, many of 
which he gave to the British Museum. 

Thad the pleasure of spending last Kastertide under his hospitable 
roof, and of finding him in full vigour of mind, and, considering 
his years, in good bodily health. I looked forward, therefore, to 
another visit; but a long and painful illness came on last autumn, 
and he died on November 15th, leaving behind him four sons and 
four daughters, all of whom I count among my personal friends.* 


Sir Joun Fowrer, Bart., K.C.M.G., Past President of the Institu- 
tion of Civil Engineers, was born near Sheffield in 1817, and was 
elected a Fellow of this Society in 1845, being therefore among 
our oldest Fellows. He was one of our great railway-engineers, 
and our Fellows are greatly indebted to him for many facilities in 
travelling to and from the Society’s house, for among his many 
works are the Metropolitan and Metropolitan District Railways. 

He died on November 20th, 1898, after a long illness. A full 
account of his life appeared in the ‘Times’ two days later, and 
probably a more detailed account will soon be published by the 
Institution of Civil Engineers. 


Lieut.-Gen. Sir Wizt1am Howry GooprenoveH, commanding the 
troops in South Africa, was born in 1833, and was elected a Fellow 


1 [Since this notice was written, an obituary has appeared in Geol. Mag. 
pp. 186-138.] 


}xil PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


of this Society in 1864. He was an officer of the Royal Artillery, 
held various staff-appointments, and saw much service in India and 
in Egypt. He died suddenly at Cape Town on October 24th, 1898. 


Cuartes GouLp was a son of Dr. Gould, the well-known natura- 
list. He was educated at the Royal School of Mines in 1854-56, 
becoming Associate in Mining, Metallurgy, and Geology, and winning 
the Duke of Cornwall’s Scholarship in 1854, the Roya! Scholarship 
and the Edward Forbes Medal in 1856. 

He joined the Geological Survey of England in 1857, about three 
months after ] had done so, and worked in the Weald, his notes 
being incorporated in Topley’s memoir on that tract. A year or 
two later he left the English Geological Survey to join that of 
Tasmania, on which country he published several Reports and papers, 
his work there ending about 1874 or 1875. 

Gould was elected a Fellow of this Society in 1859, and gave us 
two papers on Fossil Crustacea. He died at Montevideo (Uruguay) 
on April 15th, 1895, but no report of his death reached the officers 
of this Society until lately. | 


Harrison Hayter, Past President of the Institution of Civil 
Engineers, was born on April 10th, 1825, near Falmouth, and was 
educated at King’s College, London. He had a varied experience 
as an engineer in the construction of railways, of harbours, and of 
docks in many countries. 

He was elected a Fellow of this Society in 1863, and died on 
May 5th, 1898. A full account of his career will be found in 
Proc. Inst. Civ. Eng. vol. exxxiv (1898) pp. 391-394. 


\ 


Joun SHEARSoN Hyxanp was the second son of Capt. John Hyland, 
of Crosby, near Liverpool. He was educated at Merchant Taylors’ 
School, Crosby, and continued his studies at the evening classes of 
University College, Liverpool. He was engaged in the office of a 
Liverpool merchant for 4 years, and then gave up this work as 
uncongenial, going to the University of Leipzig. There he studied 
petrography under Zirkel, and took the degree of Ph.D. (in 1888) 
and M.A.in Natural Science, with first-class honours, his thesis 
for the former being an essay on the rocks of Kilimanjaro, based 
on specimens brought back to Europe by Dr. H. Meyer. 

Hyland was then appointed petrologist to the Irish branch of 
the Geological Survey, a post which he held for more than two 
years, and during his residence in Dublin he continued his studies 
at Trinity College. 


Welk 55.1] ANNIVERSARY ADDRESS OF THE PRESIDENT. lxill 


He visited the United States in 1889, and two years later left the 
Survey to go there as a mining-engineer. He was officially employed 
at the Chicago Exhibition, after the close of which he returned to 
this country. He then joined Dr. Moloney’s expedition to Rhodesia, 
and in 1898 again went to Africa, continuing his work of exploration 
and penetrating to a point 300 miles west of Lake Nyasa. His 
Fellowship of this Society dates from the same year. 

Notwithstanding the hardships that he had endured, he was 
tempted again to go to Africa, in the spring of 1898, as leader of an 
expedition to Ashanti; but, before he could leave the coast, he was 
stricken down by fever and died at Elmina on April 28th, at the 
early age of 32, 

He contributed several papers on petrology and mineralogy to 
the Transactions of the Royal Dublin Society and to the Geological 
Magazine.’ 


Wittiam Cuartes Lucy, born on June 20th, 1822, at Stratford- 
on-Avon, was the only son of Charles Lucy, a Justice of the Peace 
and sometime Mayor of that Borough. In 1850 his father started 
him as a corn-merchant at Gloucester, in which business he 
laboured with conspicuous ability and uprightness until his retire- 
ment in 1894. During this long period his energies were largely 
devoted to the social, commercial, and educational welfare of 
Gloucester and the neighbourhood, asa Magistrate, and as Chairman, 
Director, or member of various Companies and local Committees. 
No resident was more highly esteemed, none more constantly appealed 
to for help and for advice. 

Being associated during his early years with a zealous geologist, 
the late John Jones, of Gloucester, Lucy became an ardent disciple 
of his, and joined the Cotteswold Naturalists’ Club in 1859. 
Three years later he succeeded Jones as Secretary, and finally he 
became President from 1887 to 1893. He was elected a Fellow of 
our own Society in 1861. To the Proceedings of the Cotteswold 
Club he contributed many papers, the most important being on 
‘The Gravels of the Severn, Avon, & Evenlode, & their Exten- 
sion over the Cotteswold Hills’ (vol. v, p. 71); supplemented by 
another, ‘On the Extension of the Northern Drift & Boulder 
Clay over the Cotteswold Range’ (vol. vil, p. 50). Other papers 
related to the Submerged Forest near Sharpness; the Lias of 
Fretherne ; well-borings at Gloucester and Birdlip; the Lias of 


1 This notice has been compiled from an obituary published in the Magazine 
of his old school, and from information kindly furnished by Mr. F. W. Rudler. 


lxiv PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


Southerndown, Dunraven, and Bridgend; and the Inferior Oolite 
of Crickley. He also contributed in 1887 an essay on the origin 
of the Cotteswold Naturalists’ Club, with an epitome of its 
Proceedings. 

Leaving Gloucester in 1894, Mr. Lucy lived for about a year at 
Tunbridge Wells, and then settled in London, where he died on 
May 11th, 1898. He was buried near the scene of his geological 
labours, in Harescombe Churchyard, on the Cotteswold Hills.? 


The greatest loss that we have sustained in this country since the 
last Anniversary Meeting has come quite lately and unexpectedly. 
Paleontology and stratigraphy both suffer from the death, in the 
ooth year of his age, of Hzunry At~teyne NicHotson, who had been 
a Fellow of this Society since 1867, and who received the Lyell Fund 
in 1879 and the Lyell Medal in 1888. He had been in indifferent 
health for some time, but no serious results were expected. On 
January 14th, 1899, however, he had a severe breakdown through 
internal hemorrhage, and from this he did not rally, dying five 
days later. ) 

He was born at Penrith (Cumberland) on September 11th, 1844, 
and was the son of Dr. J. Nicholson, a distinguished Biblical scholar. 
It is pleasing to note that two of his own sons have had a dis- 
tinguished career at Cambridge. 

He was educated at Appleby Grammar-school and then at the 
Universities of Gottingen and Edinburgh, in both of which he gained 
high honours, taking the degrees of Ph.D. at the former, and of 
M.D. and D.Sc. at the latter, besides gaining a gold medal for his 
thesis on the Geology of Cumberland and Westmoreland, the 
Baxter Scholarship in Natural Science, and the Ettles Medical 
Scholarship. 

When only 25 years of age he was appointed lecturer on Natural 
History in the Edinburgh Extra-Academical School of Medicine. 
Then, from 1871 to 1874, he was Professor of Natural History in 
the University of Toronto, Canada. Returning to this country 
in 1874, he held the chair of Biology in the University of Durham 
(College of Physical Science) for two years. In 1875 he was 
offered and accepted the Professorship of Natural History in 
the University of St. Andrews, which he held until 1882, and 
in that year he was appointed to the corresponding chair 
in the University of Aberdeen, which he held until his death, 


2) Bok this notice Liamandebteds toad Hl iBatVioadwande 


§ of..55.| ANNIVERSARY ADDRESS OF THE PRESIDENT. lxv 


Notices of his career, to which I am indebted, and tributes to 
his high personal qualities and power of teaching, have. already 
come to us from that University.! 

Nicholson twice held the Swiney Lectureship in Geology—from 
1877 to 1880 and from 1890 to 1892, and he served as Sir Wyville 
'homson’s deputy in the University of Edinburgh during 1878 and 
the two succeeding years. . 

This long and varied professorial career, in Canada, in England, 
and in Scotland, was accompanied by much original work, especially 
with regard to Paleozoic invertebrata:—graptolites, stromatoporoids, 
corals, and polyzoa. On all these groups he has written special 
monographs or papers of great importance. To the scene of 
his earliest stratigraphical work, the Lake District, he returned 
again and again, sometimes working with the late Prof. Harkness, 
and, later on, with Mr. Marr, and our Journal has often been enriched 
by his pen. Nicholson, besides doing all this original work, wrote 
several text-books on zoology, his well-known ‘ Manual of Zoology ’ 
haying now reached a 6th edition, and his ‘Manual of Pale- 
ontology, which has long been the standard work of reference in 
this country, being now in its 3rd edition. 

The value of such a man’s life and labours, however, is not 
to be gauged simply by his published books and papers or by his 
success as a teacher. We must also take into account the personal 
help and encouragement which he gave to others, and such services 
were at all times frankly and generously rendered by Nicholson, 
whose kindly genial nature, moreover, made his companionship of 
the pleasantest. All of us were glad when he was elected a Fellow 
of the Royal Society in 1897, and several of us wondered that this 
event had not happened many years earlier. 

I cannot conclude this short notice better than by quoting the 
words of one who worked with him, knew him well, and is most 
able to appreciate his work, our former Secretary, Mr. Marr, who is 
himself preparing a notice for the Royal Society. In a letter to me, 
written soon after Nicholson’s death, after speaking of his most 
important paleontological works, Mr. Marr says that as historian of 
the Graptolites ‘he will take his place with Barrande, Hall, and 
Lapworth,’ and then adds, ‘ His stratigraphical work was also 
excellent. His discoveries in the Lake District are of permanent 
value and of far more than local importance. He was a very careful 


1 See ‘Alma Mater, Aberdeen Univ. Mag.’ vol. xvi, pp. 115-119, 121, 122, 
& portrait. 


xvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


worker in the field, and spared himself no trouble in making excur- 
sions to clear up doubtful points. He was one of the first to grasp 
the importance of the Graptolites to the geologist as well as to the 
zoologist, and, shortly before his death, returned with enthusiasm to - 
the study of these forms, which had attracted him in his youth. 
As a companion in the field he was delightful. His joyous manner 
was contagious, but it was associated with a very real seriousness. 
Indefatigable in his search after truth, he hated anything mean, 
and one could not be with him for a day without profiting by contact 
with one of so lovable a nature, who was in all ways a good man.’ * 


CHRISTOPHER OaxtnY was a Past President and one of the 
original members of the Institution of Surveyors. For many years 
he was Surveyor to the Board of Trade and Consulting Surveyor 
to the Charity Commissioners. He was elected a Fellow of this 
Society in 1864, and died on October 4th, 1898. 


Heryry Merz Ornmerop, who was born on January 10th, 1816, in 
London, was a Past President, an Honorary Member, and the last 
surviving founder of the Manchester Geological Society. 

He was elected a Fellow of our own Society in 1874, and died in 
June 1898. 


THomas Sopwitn, M.Inst.C.E., who was born at Newcastle-upon- 
Tyne on July 2nd, 1838, had long experience in mining work, 
following in his father’s footsteps, firstly at the Allenheads Mines 
and later onin Spain. He read several papers before the Institution 
of Civil Engineers, in the Proceedings of which (vol. cxxxiv, 
pp. 408-412) an account of his life is given. 

He was elected a Fellow of this Society in 1872, and died on 
July 30th, 1898, from an accident while shooting. 


In Epwarp Witson we have lost a man from whom we have had 
good work and looked forward to have more. He was born at 
Mansfield on October 30th, 1848, and was the eldest son of 
Dr. Wilson. At the age of 9 he entered the High School, Notting- 
ham, to which town his father had gone. When only 14 he wrote 
his first scientific essay on ‘ The Coalfields of Derbyshire,’ therewith 
winning the Mayor’s prize at Christmas 1862. 

In June 1865 he matriculated at the London University, and 
soon after entered the office of Mr. R. Enfield,.a well-known 


1 [Since this notice was written an obituary, with portrait, has appeared in 
Geol. Mag. 1899, pp. 138-144.] 


Walt 55... ANNIVERSARY ADDRESS OF THE PRESIDENT. lxvii 


solicitor of Nottingham. But he did not pursue legal work; for, 
as Mr. Hudleston has well put it, ‘the laws of Nature had more 
attraction for him than the laws of man.’ 

In the pursuit of science he was encouraged by his father, who 
was the first person in Nottingham to avail himself of the facilities 
offered by the Science and Art Department to found classes for 
various -sciences. Dr. Wilson had the satisfaction of seeing the 
success of this work in the creation of large classes of young pupils, 
many of whom passed the examinations with credit and some with 
distinction, including his son, who became specially certificated and 
first-class prizeman in biology and certificated teacher in geology 
(Honours) and in other subjects. Dr. Wilson died in 1868. His 
son took up his scientific work, and for 14 years held classes in 
Nottingham. 

Wilson was elected a Fellow of this Society in 1872, after he 
had published papers in the Geological Magazine and elsewhere. 
His work in the Midlands was acknowledged in 1881 by the award 
of the Darwin Medal of the Midland Union of Natural History 
Societies. . 

He was zealous in connexion with the Natural History Museum 
and the Literary and Philosophical Society of Nottingham, and 
gained a good knowledge of the physical history and of the geology 
of Nottinghamshire and Derbyshire. In January 1885, when he 
read a paper on ‘The Lias Marlstone of Leicestershire as a Source 
of Iron’ to the Nottingham Natural History Society (a few months 
after he had left the town), the members presented him with a fine 
microscope as an acknowledgment of his scientific work while he 
lived with them. 

He took up the duties of Curator of the Bristol Museum on 
September Ist, 1884, and carried them out until his death. In 
regard to his career there I may quote the following appreciative 
remarks from a local newspaper :—‘As curator of the Bristol 
Museum he was always kind and courteous, and particularly fond of 
showing to the young people any object of interest in that institution 
which he thought would arouse in them a desire to follow some 
natural-history pursuit. His knowledge of scientific literature, 
his habits of order, accuracy, and neatness, combined with a high 
sense of duty, eminently qualified him to fulfil the duties of a curator. 
He loved his Museum as only an enthusiast could. He was a 
frequent and generous contributor to it, and in all parts of the 
building may be seen the various objects of interest which from 
time to time he presented to the city of his adoption. 

‘The last important acquisition to the Museum during Mr. Wilson’s 


Ixvill PROCEEDINGS OF THE GEOLOGICAL SOCIETY, [May 1899, 


curatorship was a collection of bones, teeth, and other relics, which 
have only lately been discovered in a cave or fissure at Uphill, near 
Weston-super-Mare. This cave was explored under Mr. Wilson’s 
superintendence, and bones of the cave-bear, the mammoth, hyena, 
elephant, rhinoceros, horse, hippopotamus, and a small, but interest- 
ing, collection of worked flint-heads were found. These were in 
process of arrangement at the time of his death, and the committee 
were looking forward to their forming an interesting feature in 
connexion with the forthcoming visit of the British Association.’ 
I am glad to add that the British Association made a grant for the 
purpose of continuing this exploration. 

In 1888 Mr. Wilson received the Murchison Fund from the 
Council of this Society, in recognition of his work, at a time when 
he had contributed four papers and a short note to our Journal, 
and, partly in conjunction with others, ten papers to the Geological 
Magazine. Since then we have had three more papers wholly or 
partly from him, while four have been published in the Geological 
Magazine. Besides these, he has contributed to the Proceedings of 
the Bristol Naturalists’ Club, ete. With Mr. Hudleston he prepared 
a ‘Catalogue of British Jurassic Gasteropoda,” and this joint work 
was continued in a monograph on the British Liassic Gasteropoda 
for the Paleontographical Society. 

“Many geologists looked forward to meeting him at the Session 
of the British Association in Bristol last year, and to having his help 
not only as one of the secretaries of the Geological Section, but also 
as one of the local guides. But this was not to be: he died, at the 
comparatively early age of 49, on May 21st, 1898, after an illness 
of three weeks. A fitting tribute was paid to his memory by 
Mr. Hudleston, the President of the Geological Section, in publicly 
calling attention to a portrait of him, exhibited in the meeting- 
room, giving a short sketch of his career, and alluding to their 
joint labours. In this short ceremony I had the privilege of taking 
part, as your representative. I may conclude by quoting the words 
of a Bristol working-man: ‘ We shall feel his loss severely for some 
time. He lives in his written works, and the zeal with which he 
inspired us in our scientific pursuits.’ ? 


It is perhaps singular that in the year’s roll of loss there is not 
the name of any Fellow who has ever served on the Council. 


1 London, 1892, pp. xxxiii & 147. 

2 The above notice is based chiefly on an account published in ‘ The Bristol 
Mirror & Times’ of May 23rd, 1898, and on information supplied by 
Dr. Henry Woodward. 


Vol.’ 55. | ANNIVERSARY ADDRESS OF THE PRESIDENT. lxix 


I come now to the last and most troublesome part of my duty, 
for it is by no means easy, to me at least, to find a subject worthy 
of your consideration on this occasion, and to treat it in a befitting 
manner. 

In the few remarks that I have to make, I desire to draw your 
attention to some matters in which our science has a practical 
application. Its bearing on questions of mining has been brought 
before you at various times ; but it is in connexion with the health, 
rather than with the wealth, of the nation that I wish to speak. 

The great subject of Water-supply has been discussed by some of 
my predecessors, but only, I believe, in regard to London, not 
generally. Now, the water-supply of London is a subject pro- 
vocative of endless controversy: it has not been settled by a 
series of Royal Commissions and other kindred enquiries; indeed 
it seems still as far from being settled as ever, and to be the 
unsolved riddle of the century. I should not like to enter upon 
its consideration now, in an address that is not discussed, though 
personally I should prefer a discussion to an address. 

I am inclined to think that comparatively few geologists realize 
the importance of geological considerations in matters of Water- 
supply. Whether water is got simply by taking it as it comes 
from springs, or by impounding it in reservoirs on its way down 
streams, or by means of wells and borings (the three methods into 
which schemes for water-supply may be roughly grouped), however it 
is got, in fact, a knowledge of the character of the gathering-ground 
is essential, and this knowledge depends largely on geology. 


In the selection of sites for reservoirs more particular points 
have to be considered, especially where high dams are to be 
constructed. In such work it is well, as far as possible, to avoid 
places where there is any great disturbance, whether by faulting or 
otherwise. 

Masses of Drift, too, are sometimes troublesome, and it may be 
needful to study the composition of these and their relation to the 
rocks beneath: irregular mixtures of permeable and impermeable 
yielding material are likely to cause trouble, and the uneven 
way in which Drift so often occurs leads to uncertainty as to 
its thickness. On the whole, therefore, those parts of a valley 
with much Drift are to be avoided, although sometimes a bank or 
sheet of solid Boulder Clay may be useful. Prof. Boyd Dawkins 
has lately drawn attention to this matter, in a lecture delivered to 
the Institution of Civil Engineers,’ noticing a case, at the Ogden 

* Proc. Inst. Civ, Eng. vol. exxxiv (1898) p. 270. 


lxx PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


Reservoir (for Sheffield), where Boulder Clay made a more or less 
water-tight bottom, and another (Yarrow Reservoir, Rivington) 
where Drift (sand, gravei, Boulder Clay, and loam) filled up a deep 
pre-Glacial valley and caused much difficulty. 

Tracts in which there are large landslips are clearly dangerous ; 
for, with rocks as with men, where a slip has occurred, there 
another is likely to happen some day, as witness the Sandgate 
landslip of 1893, which was within the area of an older slip. 
Moreover, the process of cutting into a slipped mass of rock and 
earth is likely to start fresh slips, and to endanger the stability of 
the work. An instance of this may be given from the Manchester 
Waterworks in the Valley of the Etherow, several miles east of 
the city, made many years ago, when the characteristics of old 
landslipped tracts were not so well recognized as now. The lower 
part of the deep valley along which the set of reservoirs has been 
made is in Millstone Grit; but, above this, the part in which most 
of them are placed has been cut through the Millstone Grit to the 
Yoredale Beds, especially on the southern side. The Yoredale Beds 

being largely composed of shale, the conditions are favourable to 
‘springs and slips, and, as noted on the Geological Survey map 
(Sheet 88, S.E.), the greater part of the southern side of the valley 
is a landslip-area. The features of this are very clear, especially in 
the neighbourhood of the Woodhead Reservoir, the highest of the 
series, the dam of which impinges on the landslip, by Crowden 
Station. Under these circumstances, one is not surprised to hear 
that this reservoir was, for some years, never filled to within 15 or 
20 feet of its height, because it was thought unsafe to fill it, owing 
to a landslip and to the unsoundness of the embankment, until a 
new embankment had been made. I understand, indeed, that the 
dam is now practically double. 

In the above remarks I am not finding fault with this fine set of 
works, but only showing how difficulties, of anature that a geologist 
would expect, interfered with the plans of so good an engineer as 
the late Mr. Bateman. I am inclined to think, indeed, that old 
landslips are more common than most geologists suppose. In my 
Geological Survey work in Hampshire | found that the right, 
or western, bank of the Test, near Romsey, was for a long distance 
a great slip, with the usual irregular features; and later on the 
same was found to be the case with the left, or eastern, bank of 
the Itchen, opposite Southampton. In both cases no beds in place 
could be seen, except the gravel at the top. So faras I know, these 
two occurrences had never been noticed; but many others have 


Mol. 55.| ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxt 


been observed, especially in the later work of the Geological 
Survey. 

Another matter that may give trouble in a reservoir, and 
has to be guarded against, is the occurrence of permeable beds 
through which the water may find a way to lower ground, under 
favourable circumstances. An example of this may be given from 
another set of reservoirs of a like kind to that already noticed, along 
the valley of the Loxley, for the supply of Sheffield. That portion of 
the valley in which the reservoirs are placed is cut out of the upper 
part of the Millstone Grit Series, which consists of alternations of grits 
and shales. From the slight easterly dip of the beds, down the valley 
and at a higher angle than the bottom-slepe, the Middle Coal 
Measures are carried down to the bottom by the eastern end of the 
Damflask Reservoir, and in part the sides and bottom of this 
reservoir consist of a porous grit, down which water passed to below 
the dam. To get over this difficulty, a long trench had to be made 
along the southern side and filled with watertight materials. 


Coming to the consideration of the supply of water by means of 
wells, many important geological problems are brought before us, 
and some of these would otherwise escape notice. We are also 
reminded of the frequent dependence of one science upon another, 
and in this case we are specially concerned with chemistry. 

Underground water is indeed a very complicated and difficult 


subject, making strong calls on our reasoning powers. In the case 


of springs and of streams we are dealing with facts, things that 
anyone can see; but in the case of underground water it is a very 
different matter: we have to make inferences, and though our 
inferences may be warranted by all that is known on the subject, 
yet it is seldom that we can speak with certainty. There is, there- 
fore, a certain charm in questions as to underground water that 
is wanting in the more prosaic subject of surface-waters. 

Besides the element of chance, generally so delightful to frail 
humanity, the perhaps still more delightful element of superstition 
(for want of a better name) also comes in, and of late the divining- 
rod has been a good deal in evidence. I am not going to enter 
into so awful a question as to whether a forked twig can or cannot 
point out where water may be got: the literature of that subject is 
large enough already; but I should like to call attention to the 
curious fact that among the believers there are many educated 
persons, clergymen, peers, squires, ete. In a recent essay on water- 


VOL. LY. f 


lxxul PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


supply, which really amounts to a trade-circular, a well-known firm 
state that they ‘ are prepared to send an experienced diviner to locate 
water by the aid of the rod, and at the same time to give an idea 
as to the probable depth at which water may be found and approxi- 
mately the quantity available.’ It is not clear whether the firm or 
the diviner will give the particulars as to depth and quantity ; but 
it is very consoling to be told, a little farther on, that ‘it may, 
however, truly be said that although the diviner may be advan- 
tageously employed in discovering springs at a moderate depth, his 
services can never replace, for deeper and more important supplies, 
the carefully considered report of the experienced hydro-geologist.’ 

I propose to glance at some of the special points which that 
inferior creature, the experienced hydro-geologist, has to consider 
carefully in this matter, and on the assumption that a large supply 
is required, as, of course, for a small supply many points are of less 
importance. ; 

The source must be some permeable formation of good thickness 
and with a broad outcrop, as the quantity of water in any permeable 
bed must depend on the amount of rain that falls upon it, and 
this latter greatly on the area of surface exposed. A well, 
therefore, must either be upon the formation that is to be the source 
of supply or upon some overlying formation through which it can be 
carried to the water-bearing stratum. These two classes of wells 
sometimes differ greatly. 

In the first case, the well should be at a part towards which 
underground water flows: away, therefore, from an escarpment or 
ending-off of a formation, and towards the line of outcrop or where 
the next overlying formation comes on. It should also be in low 
ground, as a rule, so as to avoid needless depth. In the second 
case, when a well has to be taken through some thickness of over- 
lying beds to reach the water-bearing bed, different conditions 
sometimes arise, unless the well is near the outcrop of the water- 
bearing formation. 

The method of flow of water through the rocks must also be con- 
sidered. In some, this is mostly through the pores or the spaces 
between the particles of which the rock is built up; but in some 
water-bearing rocks very little passes in this way. Sometimes the 
planes of bedding afford a sort of channel, but at others these are 
closed and well packed together. Often the flow is along joints, or 
structural planes that have been formed after consolidation : fault- 
planes may act in a like way. 


Mol. 55. | ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxili 


Though, of course, every cpportunity of studying the rocks at the 
surface should be taken, it must not be expected that they will show 
the same features when found at great depths, beneath a thick mass 
of overlying beds. Often it is ascertained that beds which are fairly 
open in sections that can be seen have their fissures, etc., more or 
less closed up below ground: for instance, at Richmond, where the. 
Chalk has been worked horizontally under a great depth of Tertiary 
beds (from a little under to a little over 300 feet), a very great 
length of gallery has been driven with the result of cutting com- 
paratively few fissures, and none of those large, so that but little 
water has been got; while in the waterworks for Southampton, 
placed on the Chalk close to its outcrop, so that there was no occa- 
sion to sink to a great depth, a very much less amount of gallery 
has yielded a very much larger quantity of water. 

Moreover, the Kent Company, which gives our largest supply 
solely from wells, has done comparatively little in the way of 
driving galleries, but has depended largely on simple wells and 
borings, which are either on bare Chalk or where there is no great 
thickness of other beds above the Chalk. 

Again, the underground condition of a rock may vary greatly 
in places near together. The Brighton Waterworks give a good 
example of this; for, while at the Lewes Road Station the fissures 
in the Chalk are many and small, in the Goldstone Bottom Station, 
not far to the west, the fissures are mostly large, but few. Yet the 
two stations are at about the same horizon in the Chalk, and there 
is no apparent reason for this difference between them. A somewhat 
similar case is that of Croydon, where the old works, in the town, 
give a much larger supply, without galleries (or at least with 
merely short connexions between the wells), than that which 
is got from the new works, but little lower in the Chalk, at 
Addington, where there is a great length of gallery. 

These are cited as illustrations of the uncertainty of iene 
work, an uncertainty with which many of my engineering and 
some of my geological friends are fairly familiar; and they should 
prepare us to be somewhat cautious in predicting, at all events 
before we know, and I am often amused with the confidence in 
foretelling shown by folk who do not altogether know. 

For instance, quite lately, I have seen a pamphlet seriously advo- 
cating that the whole and sole water-supply of London should be got 
by means of wells sunk into the Chalk, presumably (so far as one 
can make out) within the metropolitan area! Of course, the author 


f2 


Ixxiv YROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


reproduces that old, old section of the London Basin, with the Lower 
Greensand forming a thick and continuous base. I must forbear, 
however, from entering on the controversial question of London 
water-supply, and may leave it to our Foreign Secretary (Sir John 
Kivans) to say what he thinks of a scheme that proposes taking some 
hundred or more million gallons a day from wells in the Chalk, in 
addition to the amount already obtained in that way, within the 
metropolitan district. 

Not only do we find that beds piercel at great depths often have 
a character different from that which they put on at their outcrop, 
but also that waters found at great depths often vary much in their 
mineral contents from those in the same beds much nearer the 
surface. A well-known case of this sort is that of the waters 
in the Chalk under London, where the Chalk is thickly covered by 
Tertiary beds, those waters differing greatly from the waters 
in the bare Chalk northward and southward, in the increase of 
alkaline salts and the decrease of lime-salts. Having, however, 
alluded to this subject some years ago in a Geological Survey 
Memoir, and again lately, in an address to another Society,’ I need 
not enter into it now. 

Other like cases have been described in waters from Jurassic beds, 
as at Swindon and at Woodhall Spa, in both of which a large amount 
of common salt occurs, while in the latter case there is a regular 
mineral water. It is found, too, that waters from wells in the 
sandy beds of the Wealden Series often contain a goodly proportion 
of carbonate of soda. 

Such matters, and the occurrence of mineral waters generally, 
point to the need of alliance with chemists, and the advantage of 
getting full analyses of well-waters, which show the mineral 
contents and do not merely refer to organic purity or impurity. 
With this help we may be able not only to trace the origin and 
history of a water, but may also some day learn something of those 
slow, quiet, unseen changes that go on underground, through the 
agency of water in the rocks: a subject of which, I think, we, know 
little as yet, at all events in this country. 


Although water-supply seems to be the chief sanitary subject in 
which the knowledge of the geologist is often required, there are 
1 Mem. Geol. Surv. ‘ The Geology of London & of Parts of the Thames Valley,’ 


vol. i (1889) pp. 514-516, 533, with folding table; and Trans. Herts. Nat. Hist, 
Soc. yol. x, pt. 1 (1898) pp. 11-13. 


Vol. 55. ] ANNIVERSARY ADDRESS OF THE PRESIDENT. lxxv 


other subjects which not unfrequently conflict somewhat with the 
former. Sites have, unfortunately, to be found for sewage-farms 
and for burial-grounds. For these, soils that have a fair amount of 
porosity are advantageous, and thus there is often a tendency to place 
them on water-bearing formations. 

In the matter of sewage-farms, it would be of little use to establish 
one on a stiff clay, except after a surface has been artificially pre- 
pared, a costly operation. Where, however, our great spreads of 
clay have cappings of sand, gravel or loam, good sites may be found, 
as at the well-known sewage-farm for Croydon, which is on the 
gravel of the Wandle Valley at Beddington. It is clear, therefore, 
that a geological map without Drift is comparatively useless in 
seeking for sites for the disposal of sewage. I well remember 
giving evidence, officially, as a member of the Geological Survey, 
before a Royal Commission that was investigating the disposal 
of the sewage of a not unimportant place, and that had duly 
provided itself with the Geological Survey map. It was found, 
however, that the particular maps supplied were of the usual kind, 
without Drift. On producing the proper article | was much pleased 
with the expression of the Chairman, the late Lord Bramwell, as to 
the comparative value of the two maps, albeit that it was made in 
language by no means complimentary to the Driftless map. As a 
matter of fact, the Drift map made a certain scheme worthy of 
being considered, which without it would have been at once passed 
by as absurd. 

With regard to sewage-farms, etc., it is of course important that 
sites should not be used whence damage may result to water- 
supplies, and this is often a difficult matter to determine. It 
seems, however, as if processes were coming to the front which 
may enable us to make sewage-effluents harmless; but even should 
that be the case, we ought still to guard our water-supplies from 
risk, and in doing this geology gives important help. 


As to burial-grounds, one may notice the requirements, or rather 
suggestions, of the Local Government Board, originally drawn up by 
one of our Fellows (Dr. F. Parsons), as follows :—‘ The soil of a 
cemetery should be of an open porous nature, with numerous close 
interstices, through which air and moisture may pass in a finely 
divided state freely in every direction. In such a soil decay 
proceeds rapidly, and the products of decomposition are absorbed 


Ixxvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1809, 


6 oxidized. . iv". Loam, and sand, with a sufficient quantity of 
vegetable mould, are the best soils.’ ? 

As sand is also a water-bearing earth, it is clearly essential that 
any burial-ground on it should be so placed that either the water 
from the latter shall not flow toward any wells, or, if it does, that 
there should be an ample amount of disinfecting earth between. 

Some bacteriological experiments made by Dr. Klein during last 
summer are of much interest in showing the powerful filtering effect 
possessed by fine compact sand. ‘Through his kindness I am able 
to give the results of these unpublished experiments, in a condensed 
form. They were made on Thanet Sand from near Croydon, a sand 
so firmly compacted that it stands with a practically vertical and 
even face in section, and remains thus for a long time. 

The specimens were taken at a depth of about 62 feet, and were 
found to be practically sterile, showing that the superincumbent 
layers had acted as a good filter in keeping out the many microbes 
present in the soil. 

Experiments on filtration de in the laboratory proved that even 
under the most favourable conditions, such as do not occur in nature, 
the passage of microbes through a thickness of 20 inches of the 
sand is extremely slow. In these experiments, on four occasions, a 
whole culture of special bacteria was poured on to the top of the filter. 
Such a culture yielded an amount of bacterial matter that could 
hardly be expressed by many millions.of bacteria. Yet only after 
30 days’ continuous filtration did the first bacteria appear in small 
numbers in the filtrate. ered 

Considering the amount of culture added on the top and the 
slowness with which the :first traces appeared in the filtrate, it is 
justifiable to assume that we have not simply a passage or filtra- 
tion, but an actual growing-through of the bacteria. This really 
happens, under similar experimental conditions, both with the 
Pasteur and with the Berkenfeld filters, which are the most perfect 
of their kind; and, moreover, it happens under less rigorous con- 
tinued filtration than in the experiments with the sand. 

Guinea-pigs, respectively killed by intraperitoneal injection of the 
vibrio of cholera and of typhoid bacillus, were each nailed up in 
a wooden box, and the boxes were buried in powdered sand. After 
28 days the peritoneal material gave a negative result on culture, 
no cholera vibrio occurring in one case, no typhoid bacillus in the 


1 Memorandum on the Sanitary Requirements of Cemeteries. Pp. 8. Fol. 
London, 1893. 


Vol. 55.] ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxvil 


other: all traces of the enormous mass of vibrios and of typhoid 
bacilli introduced had disappeared, although these organisms had 
increased during their sojourn of 16 to 18 hours in the living bodies. 

It is satisfactory to find that though Nature sometimes sends 
us a plentiful supply of objectionable organisms, she also provides 
means for their extinction. This bacteriocidal effect of compact 
sand is, I think, of importance. 


Having got a good water-supply, one would think that folk would 
then do their best to keep it good; but,alas! this obviously right course 
has often been neglected, not of course intentionally, but accident- 
ally or thoughtlessly ; and two cases may be noticed, one with a 
well-water and the other with a spring-water, in which disastrous 
results followed from contamination. I allude to the outbreaks of 
fever at Worthing in 1893, and at Maidstone in 1897, in which 
the epidemic was traced to the water-supply. In both cases I take 
my information from the Report of the Local Government Board on 
the subject. These are merely samples of a large number of such 
Reports. 

At Worthing it was shown ‘that the soil overlying the Chalk in 
which were sunk the wells and headings furnishing the water 
supplied ... was liable to sustained pollution by sewage... and 
there is reason to know that free communication did... exist 
between the soil above the Chalk and the new heading in the 
waterworks enclosure, by means of a fissure, which had been 
found to yield water of doubtful quality, near the surface. Experi- 
ments proved that this fissure ‘freely communicates with the new 
heading, and it is evident that, given contamination by sewage 
of the ground above and in the neighbourhood of that fissure, 
dangerous material could readily gain access to the public water- 
supply.’ } 

At Maidstone the water-supply was partly got from the Lower 
Greensand, from the Ewell and Tutsham springs, in the parish of 
West Farleigh, on the right side of the Medway Valley, 3 miles 
or more south-west of the town. These springs are thrown out 
by the Atherfield Clay from the overlying Hythe Beds, which latter 
division consists in this neighbourhood of the well-known local 
limestone, the Kentish Rag, with alternations of softer and more 
sandy beds known as hassock, the whole being generally of an 


' Dr. T. Thomson, ‘Report ...on an Epidemic of Enteric Fever in the 
Borough of Worthing ...,’ p. 17. Fol. London, 1894. 


xxviii PROCEEDINGS OF THE GEOLOGICAL society. [May 1899, 


open nature at and near the surface, so as to readily allow perco- 
lation. The gathering-grounds around some of the springs ‘ are 
covered with hop- or fruit-gardens, which are heavily manured, and 
on which great numbers of persons are employed at certain seasons 
of the year.’ The conclusion arrived at is ‘that the epidemic was 
caused by the pollution of the water,’ the chemical analyses of 
samples of which, ‘ taken from some of the springs after the epidemic 
broke out, show that the Farleigh supply had been dangerously 
polluted ; and the bacteriological examination of the samples from 
two at least of the springs afforded conclusive evidence of excre- 
mental pollution by man or the lower animals.’ The moral to be 
drawn is that ‘ chemical analyses and bacteriological examinations 
should be supplemented by skilled inspections of the actual condi- 
tions, geological, topographical, and sanitary, of the surroundings 
of the sources of supply.’* 

In leaving this subject I may refer to two Addresses, delivered 
to another body, in which several matters concerning the pollution 
of water-supplies are noticed.” 


A great deal of matter referring to water-supply is to be found 
in many of the Geological Survey Memoirs, as should be expected, 
and of late the officers of the Survey have begun to pay special 
attention to sanitary matters. The first fruit of this is the memoir 
by Mr. H. B. Woodward on ‘ Soils & Sub-soils from a Sanitary Point 
of View; with especial reference to London & its Neighbourhood, * 
and that such a work was wanted is shown by its rapid sale, an 
issue of 750 copies having been exhausted in less than two months. 
As the type was standing, further 750 copies were printed, and of 
these some 150 have been sold already. It should be noted that 
the map, printed in thirteen colours, has its divisions grouped 
by their physical characters, instead of by their geological age. 

This highly successful memoir is to be followed by others treating 
of water-supply from underground sources, by counties. The first 
of this set, devoted to Sussex, is being printed, and extends to more 
than 120 pages, chiefly devoted to accounts of wells, but giving also 
a number of water-analyses and a short introductory outline of the 


1 Borough of Maidstone: ‘ Report... on the Epidemic of Typhoid Fever, 
1897, pp. 17, 30, 38. Fol. London, 1898. 

2 Trans. Sanit. Inst. vol. viii (1887) pp. 250-258, & vol. xviii (1898) 
pp- 304-316. 

8 Pp. vi & 58, with folding coloured map. 8vo. London, 1897. 


Vol. 55.] ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxix 


geology. The second, dealing with Berkshire, is being taken in 
hand. 

In doing such work the Geological Survey is following in the 
footsteps of its founder and first chief, Sir Henry De la Beche, who, 
more than 50 years ago, carried out investigations of this sort, for 
in 1845 the Health of Towns Commission published a work by him 
entitled ‘ Report on the State of Bristol & other Large Towns,’ of 
which there is a copy in the Society’s library... This deals with 
Bath, Frome, Swansea, Merthyr Tydvil, and Brecon, giving a short 
account of the geological character of the ground and of the water- 
supply in each case, with a geological map and section for Bristol 
and a map for Bath. 


For the proper consideration of questions of water-supply and 
of other sanitary matters involving geological investigation, it 
is essential that we should have maps in which the Drift is 
shown. 

In 1863 Sir R. Murchison, then Director-General of the Geological 
Survey, decided to have the Drift shown by colour on the l-inch 
maps of that Survey, the importance of the superficial deposits from 
an agricultural point of view being then recognized, although their 
greater importance for other practical purposes was probably not so 
clearly understood. 

Unfortunately the importance of separating the various kinds of 
Drift was not realized for some time, and the mapping was done on 
the principle of lumping the whole, a proceeding that took away 
most of the value of the record, though vastly expediting its 
progress. After some time, the practical advantage of separating 
gravel andsand from loam and from Boulder Clay was seen, and the 
first map published with these divisions was that which includes 
the western half of London and the Valley of the Thames upward, 
to Henley, namely, Sheet 7, the Drift edition of which was issued 
in December 1571. Since that time the work has gone on, not only 
as regards maps in progress, but by the Drift being added to maps 
already published. 

Useful as these maps may be, especially to those geologists 
wishing to write papers on gravels, etc. (and they seem to have 
been very fruitful in this respect), they are far from being adequate 
for many practical purposes, for which a map on a much larger 
scale is often wanted. The importance of such larger maps was 


1 Pp. 102 & 3 pls. 8vo. London. 


1F.0.0.3 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


seen by De la Beche in 1854, in which year the mapping of 
Haddingtonshire on the 6-inch scale was in great part done. The 
Scottish branch of the Survey had the advantage of possessing these 
accurate detailed Ordnance maps when its work was begun, as also 
had the Irish branch, and in 1859 it was announced that ‘ the 
6-inch maps may hereafter be consulted in the Geological Map Office 
in Edinburgh.’* In the North of England work was also done on 
the 6-inch scale, and many sheets, referring to coalfields, have been 
published, but in none of them is the Drift satisfactorily treated : 
it is generally shown only by stippling, as also on some maps of 
Scottish coalfields. In Ireland the divisions of the Drift have not 
yet been shown. 

As is usual in other matters, the predominant partner in these 
islands is the worst treated. For a long time the central and 
southern parts of England were without a proper Ordnance map, 
the old l-inch sheets being to a great extent only a sketch: 
indeed I have heard that term applied to them by an officer of the 
Ordnance Survey, who objected to such things being called Ord- 
nance maps. Now, however, we have the detailed maps, and even 
a second edition of many, and they are used by the Geological 
Survey in the re-mapping of those tracts the work on which was 
done so long ago as to be anything but up to date, being without 
note of Drifts and without divisions in various thick formations of 
a more or less divisible character. 

I think that it should be clearly understood that the chief work 
of the Geological Survey is yet in a very unfinished state. What is 
now wanted, and increasingly wanted every day, is a 6-inch map of, 
at all events, the greater part of the country with all the geological 
divisions that can reasonably be made clearly shown on it, with 
such accuracy as is reasonably attainable. 

Government does not realize this, it is to be feared, and we should, 
I think, be prepared to represent the great practical utility of this 
detailed work. I have sometimes felt the want of it myself, and 
the fact that local authorities and others are often ready to pay for 
manuscript copies of 6-inch geological maps shows that others feel 
it also. Sometimes they go to the extent of having such work 
specially done for their own use; for instance, there is a geological 
map of Nottingham, on the awkward scale of 33 miles to the 
inch, enlarged from the Geological Survey map, ‘ re-surveyed and 


Rep. Sci. & Art Depart. 1858. 


Vol. 55.] ANNIVERSARY ADDRESS OF THE PRESIDENT. lxxxl 


amended in detail by J. Shipman of Nottingham, and approved by 
W. Talbot Aveline.’* 

The many manuscript copies of 6-inch maps already in existence 
at the Geological Survey Office and available for public reference are 
probably the most valuable of the many productions of that Survey, 
and they should be widely known. 

I am glad to know that some of our Fellows use the 6-inch 
Ordnance maps for recording their work in the field, and not least 
among them our new Wollaston medallist, Prof. Lapworth. While 
they must find great advantage from being able to note sections, 
outcrops, etc., with an exactness not possible without an accurate 
map on a large scale, I think that this advantage will react 
beneficially on their work, leading first to more exact and detailed 
observation, and then to greater accuracy in inference, both very 
desirable matters. Good tools save much time and trouble. 


While speaking of the Geological Survey I am moved to notice a 
subject, which most of you must remember, that somewhat stirred 
many of our Fellows last year: I mean the proposal to shift the head- 
quarters of the Survey from Jermyn Street. I took no part in the 
agitation on the matter; but, having belonged both to this Society 
and to that Survey for many years, I can hardly refrain from a few 
words. 

There is much to be said on both sides of the question, and I am 
not going to enter into any controversy. J wish only, as your 
President, to express a feeling that the close connexion between 
the Society and the Survey that has existed for so many years is 
productive only of good to both bodies. That, I believe, no one will 
deny, and I believe also that the most ardent advocates of the 
removal of the Survey to a distant part of London would be sorry 
should this result in any lessening of those bonds which link us, 
like father and son, together. 


In drawing your attention to some of the applications of geology 
I have but followed a distinguished predecessor, one of the foremost 
geologists of his time and taken from us less than two years ago, 
Sir Joseph Prestwich, in whose steps I have often had to tread. 
In his address of 1872, he remarked that, besides treating of 
‘abstract and philosophical questions, geology deals also with the 


1 Borough of Nottingham: ‘ Ann. Rep. Med. Officer of Health for 1882....’ 
by Dr. E, Seaton. 8vo. Nottingham, 1883. 


Ixxxli PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


requirements of civilized man, showing him the best mode of pro- 
viding for many of his wants,’ and that questions such as water- 
supply, etc., ‘ constitute a scarcely less important..branch of our 
science than the paleontological questions connected with the life 
of past periods, or than the great theoretical problems relating to 
physical and cosmical phenomena.’ He then notes that applied 
geology ‘is, as it were, only incidental to our general studies, and 
therefore not often the topic of our discussions, notwithstanding its 
practical importance.’ ! 

As it had been then, so it has been since, and such practical 
applications of geology as have been mentioned have had but scant 
attention from this Society: indeed, we have done little more than 
print a number of sections of wells and borings that are essential in 
sundry papers. Last year we had a small paper from Mr. Madan 
relating to fluctuation of water-level, and in 1897 a short note on 
the analyses of some African waters, from Miss Aston; in 1893 
Prof. Hull gave us a short paper referring to water-supply from 
the Lower Greensand; in 1888 we had a paper on the Durham 
salt-district from Mr. E. Wilson; in 1886, Mr. H. B. Woodward 
treated of the deep well-water of Swindon, etc.; some remarks 
on the water-supply of the Metropolis were made in 1884, by 
Prof. Judd, in his paper on the Richmond boring, and the Droitwich 
brine-springs were noticed by Mr. Parkinson. Then we may go 
back to 1876, when Sir John Evans alluded to the water-supply of 
London, at the end of his Address, and to the above-mentioned 
Address of Sir Joseph Prestwich in 1872, which deals at some 
length with ‘ Our Springs & Water-supply.’ 

This seems but little in so long a period, and I think that some of 
our younger members might well devote a little attention to questions 
of economic import. Far be it from me to suggest anything that 
would interfere withthe progress of our science: the papers brought 
before us must be chiefly concerned with science, pure and simple ; 
but surely every branch of geology ought to be represented. 

We should note, too, that the practical bearings of geology are by 
no means antagonistic to the more purely scientific pursuit of know- 
ledge. Ihave found that the necessity of looking at things from 
a more or less utilitarian standpoint sometimes makes one notice 
points that might otherwise escape attention, and the same result 
has happened to some of my friends. Onesuch case I may mention, 
from the experience of one of our Fellows who is perhaps as much 


1 Quart. Journ. Geol. Soc. vol. xxviii (187 ) p. lii. 


Vol. 55.-| ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxxiil 


devoted to science as any one can be. He had just finished a _ 
re-survey of a certain district, and very naturally thought that he 
knew nearly all about that district, when he was obliged to examine 
it again, for the purposes of an important scheme of water-supply. 
To his surprise, the looking at things from a point of view different 
from that to which he had been accustomed brought before him 
phenomena that he had not noticed previously. He became a wiser, 
but not a sadder, man. . 

Moreover, geologists should have some gratitude for the great 
amount of information which they obtain from those who are known 
as practical men, and should show it by making their science avail- 
able for practical purposes. With geology, as with other studies, 
not only should theory and practice go hand in hand, but know- 
ledge, gained from both, should be applied to useful purposes and 
for the public good. 


lxxxiy PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1899, 


February 22nd, 1899, 
W. Wuiraxer, B.A., F.R.S., President, in the Chair. 


George Hartley Ballard, Esq., M.Sc., Grammar School, Berwick- 
upon-T'weed ; Thomas Kidd, Esq., Assoc.M.Inst.C.E., Claremont 
Villa, Swadlincote, near Burton-on-Trent; and Alexander Grant 
Ogilvie, Esq., Mount Lyell (Tasmania), were elected Fellows of 
the Society. 


The List of Donations to the Library was read. 


The following communications were read :— 


1. ‘On Varieties of Serpentine and Associated Rocks in Anglesey.’ 
By Prof. T. G. Bonney, D.Sc., LL.D., F.R.S., F.G.S., and Miss C. 
A. Raisin, D.Sc. 


2. ‘Remarks on the Genera Hetomaria, Koken, and Hormotoma, 
Salter ; with Descriptions of the British Species.’ By Miss Jane 
Donald. (Communicated by J. G. Goodchild, Esq., F.G.S.) 


The following specimens were exhibited :— 


Rock-specimens and Microscope-sections, by Prof. T. G. Bonney, 
D.Se., LL.D., F.R.S., F.G.8., in illustration of his and Miss C, 
A. Raisin’s paper. 

Specimens and Casts, exhibited on behalf of Miss Jane Donald, in 
illustration of her paper. 


The following Maps were exhibited :— 


Geological Survey of England & Wales: 1-inch map, 46 S.E. 
(Drift) and n. s. 350, Torquay (Drift); Geological Survey of Ireland : 
29 (Carrickfergus); Geological Survey of Scotland: 7 (Ballantrae), 
13 (Arran) 40 (Kinross), 57 (Forfar), 67 (Stonehaven), and 115 
(Reay). Presented by the Director-General of H.M. Geological 
Survey. 

Geological Survey of Western Australia: Geological Map of 
Northampton, drawn up and presented by A. G. Maitland (Govern- 
ment Geologist). 

Geological Survey of South Australia: Geological Map of the 
Northern Territory, drawn up and presented by H. Y. L. Brown 
(Government Geologist), 


Vol. 55.] | PROCEEDINGS OF THE GEOLOGICAL SOCIETY. lxxxv 


March 8th, 1899. 
W. Wuairaxer, B.A., F.R.S., President, in the Chair. 


William Harcourt Branscombe, Esq., B.A., Halkyn (Flintshire) ; 
Allen S. Heath, Esq., 67 Trentham Road, Longton (Staffordshire) ; 
and William Pollard, M.A., Ph.D., 28 Jermyn Street, S.W., were 
elected Fellows of the Society. 


The List of Donations to the Library was read. 


The following communications were read :— 


1. ‘An Analysis of the Genus Micraster, as determined by rigid 
Zonal Collecting, from the Zone of Rhynchonella Cuviert to that of 
Micraster cor-anguinum.’ By Dr. A. W. Rowe, F.G:S. 


2. *On a Sill and Faulted Inlier in Tideswell Dale (Derbyshire).’ 
By H. H. Arnold-Bemrose, Esq., M.A., F.G.S. 


The following specimens, maps, and photographs were ex- 
hibited :— 


Specimens and Lantern-slides, exhibited by Dr. A. W. Rowe, 
F.G.S., in illustration of his paper. 

Rock-specimens and Microscope-sections, Lantern-slides and 
Photographs, exhibited by H. H. Arnold-Bemrose, Esq., M.A., 
F.G.S., in illustration of his paper. 

Geological Survey of Scotland: 1-inch map, Sheet 85. Rothes 
(Elgin) by J. 8. Grant-Wilson and others, presented by the Director- 
General of H.M. Geological Survey. 

Thirty Platinotype Photographs (cabinet size) of Fellows of the 
Society, presented by Messrs. Maull & Fox, Photographers. 


March 22nd, 1899. 


W. Wuiraker, B.A., F.R.S., President, in the Chair. 


William Earl Hughes, Esq., B.A., 8 Clifford’s Inn, E.C.; John 
Thomas Stobbs, Esq., A.Sc., Stoke-upon-Trent ; Edgar Duesbury 
Wellburn, Esq., Beech House, Sowerby Bridge (Yorkshire); and 
Charles Louis Napoleon Wilson, Esq., Assoc.M.Inst.C.E., Bangor 
Villas, Bilston, were elected Fellows of the Society. 


The List of Donations to the Library was read. 


The following communications were read :— 


1. ‘ Relations of the Chalk and Drift in Moen and Riigen/’ 
By Prof. T. G. Bonney, D.Se., LL.D., F.R.8., F:G.8., and the 
Rey. Edwin Hill, M.A., F.G.S8, 


Ixxxvi PROCEEDINGS OF THE GEOLOGICAL society. [May 1899. 


‘A Critical Junction in the County of Tyrone.’ By Prof. 
Granville A. J. Cole, F.G.S. 


The following specimens, photographs, and maps were ex- 
hibited :— , 


Photographs of Rigen, exhibited by Prof. T. G. Bonney, D.Sc., 
LL.D., F.R.S., F.G.S., in illustration of his and the Rev. Edwin 
Hill’s paper. 

Rock-specimens, exhibited by Prof. Grenville A. J. Cole, F.G.S., 
in illustration of his paper. 

Bobbin of Indurated Shale found at Howietoun, Stirling, ex- 
hibited by H. W. Monckton, Esq., F.L.S., F.G.S. 

Photograph of Glacier-table on Double Pinnacle, Oberaletsch 
Glacier, taken by Dr. T. Anderson, F.G.S., exhibited by H. W. 
Monckton, Esq., F.L.8., F.G.S. 

Rock-specimens from Frederick Henry Bay (Tasmania), exhibited 
by T. Stephens, Esq., M.A., F.G.S. 

Geological Survey of England and Wales: J-inch map, n. s., 
Sheets 267 & 283 (Drift), presented by the Director-General of H. M. 
Geological Survey. 

Geological Survey of Western Australia: Geological Map of the 
Collie Coalfield, drawn up and presented by ieee Maitland, Esq., 
F.G.S. (Government Geologist). 


ae eee 


April 12th, 1899. 
W. Wuiraxer, B.A., F.R.S., President, in the Chair. 


William Anderson, Esq., Government Geologist, Pietermaritzburg, 
Natal (South Africa); Charles Ekin, Esq., F.I.C., F.C.S., Fieldhead, 
Corkran Road, Surbiton ; William G. Snowden Gard, Esq., LL.B., 
20 Upper Park Road, Hampstead, N.W.; and George Arthur 
Mitcheson, Esq., Hem Heath, Trentham (Staffordshire), were 
elected Fellows of the Society. 


The List of Donations to the Library was read. 


The following communications were read :— 


1. ‘Fossils in the University Museum, Oxford.—I. Silurian 
Echinoidea and Ophiuroidea.’ By Prof. W. J. Sollas, M.A., D.Sc., 
LL.D., F.B.S., F.G.8. 


2. ‘On the Occurrence of Sponge-spicules in the Carboniferous 
Limestone of Derbyshire.’ By Prof. W. J. Sollas, M.A., D.Sc., 
LL.D., F.RB.S., F.G.S. 


3. ‘On Spinel and Forsterite from the Glenelg Limestone.’ By 
C. T. Clough, Esq., M.A., F.G.S., and Dr. W. Pollard, M.A., F.G.S. 


Vol. 55.] | PROCEEDINGS OF THE GEOLOGICAL SOCIETY. “xxxvil 


Mr. A. M. Davins, in exhibiting a specimen of glauconitic lime- 
stone from the Kimeridge Clay, said that it might easily be taken 
for Upper Greensand. It came from aroad-cutting near Wombwell’s 
Farm, Chilton (Bucks), about 40 feet below the top of the Hartwell 
Clay, and therefore evidently from the true Kimeridgian. The 
outcrop of the stone gives rise to a slight but distinct feature, 
traceable for about ; mile along the hillside. There are traces 
of fossils in the stone, but an impression of a bip]ex Ammonite 
was alone recognizable. No similar bed had been previously 
recorded from the English Kimeridgian. 


In addition to the specimen mentioned above the pe were 
exhibited :— 


Specimens, Microscope-sections, and Lantern-slides, exhibited by 
Prot. W.J. Sollas, M.A., LL.D., D.Se., FR. S., in illustration of his 
papers. 

Specimens and Microscope-sections exhibited by C. T. Clough, 
Esq., M.A., F.G.S., and Dr. W. Pollard, M.A., F.G.S., in illustration 
of their paper. 

Boulder of Igneous Rock found in Drift 300 feet above O.D., 
near Norton Heath (Essex), exhibited by A. E. Salter, Esq., F.G.S._ 

Map :—Angabe der, im Betrieb stehenden und im Aufschlusse 
begriffenen, Lagerstatten von Edelmetallen, Erzen, Eisensteinen, 
Mineralkohlen, Steinsalz u. anderen nutzbaren Mineralien auf dem 
Territorium der paneer der Ungarischen Krone, von J. Bockh u. 


A. Gesell: scale 1898, presented by the Royal Hungarian 
Geological Survey. 


900, -a00? 


April 26th, 1899. 
W. Wuiraxer, B.A., F.R.S., President, in the Chair. 


Hyman Herman, Esq., B.C.E., Department of Mines, Victoria 
(Australia), and Francis Beaumont Stephens, Esq., Lecturer on 
Metallurgy and Determinative Mineralogy at Otago University, 
Dunedin (New Zealand), were elected Fellows of the Society ; 
Prof. Emmanuel Kayser, of Marburg, was elected a Foreign 
Member; and Prof. Franz Lcewinson-Lessing, of Dorpat, and 
Prof. R. Zeiller, of Paris, were elected Foreign Correspondents of 
the Society. 


The List of Donations to the Library was read. 


The Presrpent drew attention to the presentation by Dr. H. C. 
Sorsy, F.R.S., past-President G.S., of an autotype portrait of himself. 
He understood that the portrait was a reproduction of one which 
had been painted in commemoration of Dr. Sorby’s long connexion, 
no less than 52 years, with the Sheffield Microscopical Society, as 
a Member of its Ccuncil. He thanked Dr. Sorby on behalf of 
the Fellows of the Geological Society, and expressed the pleasure 
which they felt at seeing him among them that evening. 


VOL. LY. g 


Ixxxviil PROCEEDINGS OF THE GEOLOGICAL society. [Aug. 1899, 


The following communications were read :-— 


1. ‘On Limestone-knolls in the Craven District of Yorkshire 
ie elsewhere.’ By J. E. Marr, Esq., M.A., F.R.S., F.G.S. 


‘The Limestone-knolls below Thorpe Fell, between Skipton 
1 iGincmeten in Craven.’ By J. R. Dakyns, Esq., M.A. (Com- 
municated by the President.) | 


3. ‘On Three new Species of Lamellibranchiata from the Car- 
boniferous Rocks of Great Britain. By Dr. Wheelton Hind, 
F.R.CS., F.G.S. 


The following specimens, photographs, & maps were exhibited :— 


Specimens, Microscope-sections, and Photographs, exhibited by 
J. E. Marr, Esq., M.A., F.R.S., F.G.S., in illustration of his paper. 

Specimens exhibited by Dr. ‘Wheelton Hind, F.R.C.S,, 1 Gsm 
illustration of his paper. 

Specimens of Conglomerate-breccia from Skipton, Grassington, etc., 
and Photographs, exhibited by R. H. Tiddeman, Esq., M.A., F.G.S. 

Geological Survey of England and Wales: 1-inch Map, Sheet 248, 
Pontypridd (Solid & Drift), and Sheet 282, Devizes, presented by 
the Director-General of H.M. Geological Survey. 


——_—_—_——. 


May 10th, 1899. 
W. Wauiraxer, B.A., F.R.S., President, in the Chair. 


Capt. Archibald William Hicks Beach, Wick House, Downton 
(Wiltshire); Alexander Montgomerie Bell, Esq., M.A., 7 Rawlinson 
Road, Oxford; George Clinch, Esq., Clerk to the Society of 
Antiquaries of London, 22 Nicholson Road, Addiscombe (Surrey) ; 
Frederick George Collins, Esq., 43 Powderham Crescent, Exeter ; 
and Minett Edward Frames, Esq., Box 3517, J ohannesburg (South 
African Republic), were elected Fellows of the Society. 


The List of Donations to the Library was read. 
The following communications were read :— 


1. ‘The Geology of the Davos District (Switzerland).’ By 
A. Vaughan Jennings, Esq., F.L.S., F.G.8. 


2. ‘The Lower Paleozoic Bedded Rocks of the Waterford Coast.’ 
By F. R. Cowper Reed, Esq., M.A., F.G.S. 


The following specimens and maps were exhibited :— 


Rock-specimens and Microscope-sections, exhibited on behalf of 
A. Vaughan Jennings, Esq., F.L.S., F.G.S., in illustration of his paper. 

Rock-specimens and Microscope-sections, exhibited by F. R. 
Cowper Reed, Esq., M.A., F.G.S., in illustration of his paper. 

Stone-implement from Scaling, Cleveland District (Yorks), 
obtained from a gravel-deposit at a distance of 2 feet below the 


Vol. 55.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. Ixxxlx 


surface in the year 1874, by Mr. J. Garbutt, exhibited by 
A. E. Salter, Esq., B.Sc., F.G.S. 

Geological Survey of Scotland: 1-inch Map, Sheet 19 (Bowmore), 
presented by the Director-General of H.M. Geological Survey. 


May 24th, 1899. 
W. Wairaxer, B.A., F.R.S., President, in the Chair. 


James Ronald Eccles, Esq., B.A., King’s College, Cambridge, and 
EK. R. Matthews, Esq., C.H., Surveyor’s Office, Bridlington Quay, 
were elected Fellows of the Society. 


The List of Donations to the Library was read. 


The Presrpent called attention to the issue of Vol. III. of 
Hutton’s ‘ Theory of the Earth,’ and said that the thanks of the 
Fellows were due to Sir A. Geikie for having edited and annotated 
most. carefully this work. The volume was printed from a pre- 
viously unpublished manuscript which had been for many years in the 
possession of the Society: its contents were extremely interesting, 
and it supplemented the previous volumes by the inclusion of an 
index to the whole of the work, prepared by Sir A. Geikie. 


Prof. SzrLey exhibited acast from a footprint obtained by Mr. H. 
C. Beasley from the Trias at Stourton. The impression is about 
14 inch long, and nearly as wide. The cast has been treated by 
oblique illumination, so as to display its osteological structure by 
means of the shadows thus thrown. All the claws are directed 
outward, as in a burrowing animal. The form of the foot resembles 
that of a monotreme mammal rather than that of any existing reptile. 
There appears to be a slender pre-pollex including three bones. The 
only other example of this structure in the Trias is in the theriodont 
reptile Theriodesmus, in which it is less definite. This character 
may add to the interest of other footprints from Stourton, which in 
the form of the foot approximate to anomodont reptiles from the 
Karoo Beds of Cape Colony. 


The following communications were read :— 


1. ‘On the Distal End of a Mammalian Humerus from Tonbridge 
(Hemiomus major). By Prof. H. G. Seeley, F.R.S., F.L.S., F.GS. 


2. ‘On Evidence of a Bird from the Wealden Beds of Ansty 
Lane, near Cuckfield.’ By Prof. H. G. Seeley, F.R.S., F.L.S., F.G.S. 


3.‘ Notes on the Rhyolites of the Hauraki Goldfields (New 
Zealand). By J. Park, Esq., F.G.S., and F. Rutley, Esq., F.G.S. ; 
with Analyses by P. Holland, Esq., F.1.C., F.C.S. 


4. ‘On the Progressive Metamorphism of some Dalradian 
Sediments in the Region of Loch Awe.’ By J. B. Hill, Esq., R.N. 
(Communicated by Sir A. Geikie, D.Sc., LL.D., F.R.S., F.G.S.) 


Xe PROCEEDINGS OF THE GEOLOGICAL socrnTy. [Aug. 1899, 


In addition to the specimen described on p. lxxxix, the following 
were exhibited :— 


Distal end of a Mammalian Humerus from Tonbridge, and distal 
end of Femur of a Bird from the Wealden Beds of Ansty Lane, near 
Cuckfield, exhibited by Prof. H. G. Seeley, F.R.S., F.LS., F.GS., 
in illustration of his papers. 

Rock-specimens and Microscope-sections of Hauraki Rhyolites, 
exhibited by J. Park, Esq., F.G.S., and F. Rutley, Esq., F.G.S., 
in illustration of their paper. 

Rock-specimens from the Loch Awe District and Microscope- 
sections, exhibited by the Director-General of H.M. Geological 
Survey, in illustration of the paper by J. B. Hill, Esq., R.N. 

Pecten sp. from the Chalk Marl, Blue Bell Hill Pit, Barham, 
Rochester, and Hippurites sp. from the Chalk of Wouldham, 
Rochester, exhibited by G. E. Dibley, Esq., F.G.S. 

Bones of a large bat (Pteropus) found with bones of Dodo at 
Mare-aux-Vaquois (Mauritius); and Slab of Stonesfield Slate 
crowded with impressions of Trigonia impressa, also showing 
the second phalange of the wing-finger of a Pterosaur (probably 
Ornithochewrus), exhibited by W. F. Gwinnell, Eisq., F.G.S. 


June 7th, 1899. 
W. Warraxer, B.A., F.R.S., President, in the Chair. 


Joseph Crankshaw, Esq., Montcliffe, Horwich (Lancashire) ; 
William Bruce Dallas Edwards, Esq., 59 Waldeck Avenue, Bedford ; 
Lieut.-Col. Thomas English, Hawley, near Dartford (Kent); and 
Herbert Lapworth, Esq., Stud.Inst.C.E., 20 Duchess Road, Edg- 
baston, Birmingham, were elected Fellows of the Society. 


The List of Donations to the Library was read. 


The Names of certain Fellows were read out for the first time, in 
conformity with the Bye-Laws, Sect. VI, Art. 5, in consequence of 
the non-payment of their Arrears of Contributions. 


Mr. F. A. Baraer, in exhibiting, on behalf of Mr. R. D. 
Darbishire, a pebble found in gravel near St. Margaret’s, Bowdon 
(Cheshire), said that it consisted of liver-coloured quartzite and no 
doubt once formed part of the Bunter Pebble-beds, though these do 
not occur in the immediate neighbourhood of Bowdon. It had 
been reported to Mr. Darbishire as found in river-gravel; but 
reference to Sheet 80 N.E. of the Geological Survey map (1-inch, 
Drift) showed that the deposit was Drift of alleged glacial origin. 
The specimen was an exceedingly perfect and characteristic example 
of the pyramid-pebbles or ‘ Dreikanter,’ such as are found in the 
Diluvium of the North German plain, and in other parts of 
the world from the Cambrian to rocks now forming, but hitherto 
not recorded from England. These have been explained as due to: 
(1) human agency, (2) glacial action (Theile), (3) compression in a 


Woll 55.1 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. xcl 


pebble-bed (‘ Packungstheorie’ of Berendt), and (4) action of wind 
andsand. The last explanation was the only one that met the facts 
of the case, as proved by A. von Mickwitz, Mém. Soc. Imp. Mineral. 
St. Pétersb. ser. 2, vol. xxii (1887) pp. 82-98, pls. viii & ix. 

In illustration of his remarks, Mr. Bather exhibited a series 
of specimens which had been collected under the guidance of 
A. von Mickwitz from the locality described by that author (shore 
of the Obersee, south of Reval, Esthonia). They confirmed the 
statement that the three sides of the pyramids lay at right angles 
to the directions of the prevailing winds of the district; they 
showed stages between stones eroded on one face, or on two faces, 
and the typical ‘ Dreikanter’; they illustrated the polishing action 
of the agent on hard, fine-grained material, its differentiating 
action on coarse-grained; they retained the original waterworn 
surface and shape on the under side, and a growth of lichen on 
such small portions of the upper surface as had been sheltered 
from the wind. Applying this explanation to Mr. Darbishire’s 
specimen, there still remained an unsolved problem: Was the 
pebble eroded before or during the deposition of the Bunter 
stratum, or at some time before, during or subsequent to the 
transport and deposition of the Drift? The mode of occurrence 
of the North German specimens shows that they were eroded after 
the deposition of the beds at the top of which they now lie; and, 
in the absence of contrary evidence, the same answer must be 
given provisionally to the preceding questions. 


The following communications were read :— 


1. ‘On the Geology of Northern Anglesey.’ By C. A. Matley, 
Esq., B.Sc., F.G.S. ; with an Appendix on the Microscopic Study of 
some of the Rocks, by Prof. W. W. Watts, M.A., Sec.G.S. 


2. ‘On an Intrusion of Granite into Diabase at Sorel Point 
(Northern Jersey).’ By John Parkinson, Esq., F.G.S. 


In addition to those described on pp. xe and xci, the following 
specimens, etc., were exhibited :— 


Rock-specimens, Microscope-sections, and Photograph, exhibited 
by C. A. Matley, Esq., B.Sc., F.G.S., and Prof. W. W. Watts, M.A., 
Sec.G.S., in illustration of their paper. 

Rock-specimens and Microscope-sections, exhibited by John 
Parkinson, Esq., F.G.S., in illustration of his paper. 

A portion of an Ammonite from Cromer Beach, below the great 
slip (Easter 1898), exhibited by A. E. Salter, Esq., B.Sc., F.G.S. 

_ Geologische Karte der im Reichsrathe vertretenen Kénigreiche und 


Lander der Oesterreichisch-Ungarischen Monarchie : art Lief. 1 
& 2, 1898. Presented by the Director of the Imperial Austro- 


Hungarian Geological Survey. 


VOL, LY. h 


Xill PROCEEDINGS OF THE GEOLOGICAL society. [Aug. 1899. 


June 21st, 1899. 
W. Wuirtaxer, B.A., F.R.S., President, in the Chair. 


Robert Arthur Buddicom, Esq., B.A., Ticklerton Court, Church 
Stretton (Shropshire); Daniel Carmichael, Esq., F.R.C.S., Gosforth, 
Neweastle-on-Tyne ; and James Tonge, Jun., Esq., 24 Hampton 
Road, Southport, were elected Fellows; Senhor J. F. N. Delgado, 
of Lisbon ; and M. Ernest Van den Broeck, of Brussels, were elected 
Foreign Members; Prot. C. E. Beecher, of Yale University, New 
Haven (Conn.), U.S.A.; and Herr Gerhard Holm, of Stockholm, 
were elected Foreign Correspondents of the Society. _ 


The List of Donations to the Library was read. 


The following names of Fellows of the Society were read out for 
the second time, in conformity with the Bye-Laws, Sect. VI, Art. 5, 
in consequence of the non-payment of their Arrears of Contyri- 
butions:—R. pr Arreaea; Dr. W. J. Coomszs; S. Farnrieqp; 
Rev. C. F. B. Hawxins; H. E. Hurst; Dr. J.C. Ross; R. Russenz; 
H. K, Sparx; R. L. Tarscorr; and A. H. 8. Wurre. 


The folowing communications were read :— 


1. ‘On the Agglomerates and Tuffs in the Carboniferous Lime- 
stone Series of Congleton Edge.’ By Walcot Gibson, Esq., F.G.S., 
and Dr. Wheelton Hind, F.R.C.S., F.G.S. With an Appendix on 
the Petrography of the Igneous Rocks by H. H. Arnold-Bemrose, 
Esq., M.A., F.G.S. 


2. ‘On some Ironstone Fossil Nodules of the Lias.’ By E. A. 
Walford, Hsq., F.G.S. 


3. ‘ Additional Notes on the Glacial Phenomena of Spitsbergen,’ 
By E. J. Garwood, Esq., M.A., F.G.S. 


4, ‘Additional Notes on the Vertebrate Fauna of the Rock- 
Fissure at Ightham (Kent). By HE. T. Newton, Esq., F.R.S., 
F.G.S8. 


The following specimens and photographs were exhibited :— 


Rock-specimens, exhibited by Dr. Wheelton Hind, F.R.CS., 
F.G.S., in illustration of his and Mr. Gibson’s paper. 

Rock-specimens, Microscope-sections, and Photographs, exhibited 
by H. H. Arnold-Bemrose, Esq., M.A., F.G.S., in illustration of his 
Appendix to the above-mentioned paper. 

Liassic Ironstone Fossil Nodules, exhibited by E. A. Walford, 
Ksq., F.G.S., in illustration of his paper. 

A series of Photographs and Lantern-slides exhibited by EK. J. 
Garwood, Esq., M.A., F.G.8., in illustration of his paper. 

Paleolithic Core, Implements, and Flakes from the Thames 
Valley Drift at High Holborn and Throgmorton Street, London, 
exhibited by 8. H. Warren, Esq., F.G.S. . 


- 


pee ee Ps OS 5" 


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Coy 


CONTENTS. 


PAPERS READ. 

| Page 

36. Mr. E. J. Garwood on the Glacial Phenomena of Spitsbergen. (Plates 
ERT RATS ALD) iss etanls de oP seer eeate vt sa ob es a dgsc <s'egas ne satel axe on eau degecae ean 681 


37. Prof. W. J. Sollas on Silurian Hchinoidea and Ophiuroidea in the Oxford 
Tin verstiy NLMSCUM |< i245... lor co¥ ha ahdeerew edi ye se ow oes deur. gs occnwen es 692 


38. Prof. W. J. Sollas on the Occurrence of Sponge-spicules in the Carboniferous 
Limestone of Derbyshire ...... Sitagees «SV CP Ep eR eves awe soucl ye keto tee een 716 


39. Mr. F. R. ©. Reed on the Lower Paleozoic Bedded Rocks of County 
MV aueriord.;-. (kate, MbrL XE) 0. piece. onc tee ath canoes dctetons ie ap eae ee 718 


(Tirtz-PAGE, INDEX, TaBLE or Contents, ete. to Vol. LY.) 


[No. 221 will be published next February. | 


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Authors alone are responsible for the facts and opinions contained in their respective 
Papers. | 


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hands. Unless this is done, it will be in the discretion of the Officers to return the 
communication to the Author for revision. 


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conversational purposes only. 


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