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THE

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 lis uti, sed ad ulteriora
penetrare ; atque non disputando adversarium, sed opere naturam vincere ; denique non belle et probabiliter
opinari, sed certo et ostensive scire ; tales, tanquam veri scientiarum filii, nobis (si videbitur) se adjungant.
—Novun Organum, Prefatio.

VOLUME THE SIXTY-SEVENTH.
ROE:

LONDON :

LONGMANS, GREEN, AND CO.
PARIS: CHARLES KLINCKSIECK, 11 RUE DE LILLE.
SOLD ALSO AT THE APARTMENTS OF THE SOCIETY.

MDCCCCXI,

2205ba

“tt

ORL T CHS

OF THE

GEOLOGICAL SOCIETY OF LONDON.

anna

Elected Bebauaty pith, 1911.

PAA

President.
Prof. William Whitehead Watts, Sc.D., LL.D., M.Sc., F.R.S.

WicezPrestvents,
Charles William Andrews, B.A., D.Se., | John Edward Marr, Se.D., F.R.S.

E.R.S. Prof. William Johnson Sollas, LL.D.
Alfred Harker, M.A., F.R.S. | Se.D., F.RS.
Secretaries.

Prof. Edmund Jobnston Garwood, M.A. | Arthur Smith Woodward, LL.D., F.RB.8.

Foreign Decretarp. Creasurer.

Sir Archibald Geikie,K.O.B.,D.0.L.,LL.D., | poe Strahan, Sc.D., F.R.S.
Se.D., Pres.R.8.

COUNCIL.

Henry A. Allen. Robert Stansfield Herries, M.A.
Tempest Anderson, M.D., D.Sc. Bedford MeNeill, Assoc.R.S.M.
Charles William Andrews, B.A., D.Sc., | John Edward Marr, Sc.D., F.R.S.

E.R.S. George Thurland Prior, M.A., D.Se.
Henry Howe Arnold-Bemrose, J.P., Sc.D. | Prof. Sidney Hugh Reynolds, M.A.
George Barrow. Prof, William Jobnson Sollas, LL.D.,Se.D.,
Prof. Thomas George Bonney, Sc.D., FE.RB.S.

LL.D., F-B.S. | Aubrey Strahan, Sc.D., F.R.S.
Prof. William S. Boulton, B.Se. Herbert Henry Thomas, M.A., B.Se.
James Vincent Elsden, D.Sc. Prof. William Whitehead Watts, Se.D.,
John Smith Flett, M.A., D.Sc. LL.D., M.Sce., F.R.S.

Prof. Edmund Johnston Garwood, M.A. The Rev. Henry Hoyte Winwood, M.A.

Sir Archibald Geikie, K.C.B., D.C.L., | Arthur Smith Woodward, LL.D., F.R.S.,
LL.D., Sc.D., Pres.R.S. LDADESE

Alfred Harker, M.A., F.R.S.

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

Assistants in Office, Library, and Museum. -

W. Rupert Jones. Clyde H. Black.
Arthur Greig.

STANDING PUBLICATION COMMITTEE.
Prof. W. W. Watts, President.

rof. EH. J. Garwood,

Dr. A. Smith Woodward, \ Secretaries.

Mr. H. A. Allen. Dr. J. E. Marr.

Dr. C. W. Andrews. Dr. G. T. Prior.

Dr. J. V. Elsden. Prof. 8. H. Reynolds.
Dr. J. S. Flett. Prof. W. J. Sollas.
Mr. A. Harker. Dr. A. Strahan.

Mr. R. S. Herries. Mr. H. H. Thomas.

TABLE OF CONTENTS.

Botton, Herperr. Ona Collection of Insect-Remains from the
South Wales Coalfield (Plates VII-X)

CMOS OOF On SOOO Oe iorUacy co ORONO

——. Faunal Horizons in the Bristol Coalfield (Plate XXVII) ..

Boutton, Prof. Witt1amS. Ona Monchiquite Intrusion in the
Old Red Sandstone of Monmouthshire (late XOX VAT. :..
CHAPMAN, FREDERICK. Foraminifera, Ostracoda, & Parasitic
; Fungi from the Kainozoic Limestones of CHMONAC si is. i eyes «
CopzoLtD, Epear Sreruine. Trilobites from the Paradoxides
Beds of Comley, Shropshire (Plates PORT EIORIVLY St eyo,
Conuins, FrepERicK GuorGr. Notes on the Culm of South
Devon: Part I—Exeter District (Plate 2.0.0: aie er eae nae
Crick, GrorGe C. Notes on Carboniferous Cephalopoda from the
Neighbourhood of Exeter

ceitndiince Be bomen #0 © 2S S Shin lran reine vasle\ eye \.ecvelen.e1-: <0) te eh eat

DisiEy, GrorGE Epwarp. On the Teeth of Ptychodus and their
Distribution in the English Chalk (Plates XVII-XXII)......
Dixon, Ernest Epwarp L&sziz (& Dr. A. VaueHan):' The
Carboniferous Succession in Gower (Glamorganshire), with

Notes on its Fauna & Conditions of Deposition (Plates
XXX VIII-XLI)

ret eS EOS ORE Metal 9D S003 ORO MCG DCEO CRD ELS Ch aber ewes eee

GreGory, Prof. Joun Water. The Geology of Oyrenaica
(Plate X LIT)

=== ie Hpaeil Kchinoidea of Cyrenaica (Plates XLVII-XLIX).

Guppy, R. J. Lecumere. On the Geology of Antigua and other
West Indian Islands, with reference to the Physical History of
the Caribean Region (Plate L)

cmon r= 16 0) MLO; Os mca) evita awe es eiele teria. a

Home, Dr. Wittiam Fraser. The Effects of Secular Oscillation
in Egypt during the Cretaceous and Eocene Periods (Plate VI).

Martey, Dr. Coarnes ALFRED. Notes on some of the Brachiopoda
from the Paradowvides Beds of Comley (Plate XXVI pars)

oS 66 «

Newron, Ricuarp Butten. Kainozoic Mollusea from Cyrenaica
(Plates XLITI-XLVI)

Sie ai periate, eS) SM be elec lel BL sieh eke 'el ip 62 0, s) iho) aa) o) aha

PECs tee g a” onionomersneliel ane feveleh oMelte:. as! etecs fete es Are... 4€

Page

516

393

399

263

681

118

300

lv TABLE OF CONTENTS.

Page
RasTaLui, RopERT Heron. The Geology of the Districts of Wor-
cester, Robertson, & Ashton, Cape Colony (Plate LI) ........ 701

ReEyNo ps, Prof. Sipnry Huew (& Dr. A. VauGHaN). Faunal and
Lithological Sequence in the Carboniferous Limestone Series
(Avonian) of Burrington Combe, Somerset (Plates XXVIII-
RIND) i ia vials Where elas ase clete hel tale i'l Wiss diniadecd) ss ee 342

RicHarpson, Linspaty. The Rheetic and Contiguous Deposits of
West, Mid, & Part of East Somerset (Plates I-IV) .......... I

SHERLOCK, Dr. RopeRT Lioneu. The Relationship of the Permian
to the Trias in Nottinghamshire) (Plate V))|...... 22.2 eeeeeee 75

THomas, HERBERT Henry. The Skomer Volcanic Series (Pem-
brokeshire (Plate X1)s occa ieee. walk: . ss cde cer 175

VaucuHan, Dr. AntHUR (& Prof. S. H. Reynoxtps). Faunal and
Lithological Sequence in the Carboniferous Limestone Series
(Avonian) of Burrington Combe, Somerset (Plates XX VIII-
AX XD) SR heen tart ev ale eo tie ole anette 342

—— (& E. E. L. Drxon). The Carboniferous Succession in Gower
(Glamorganshire), with Notes on its Fauna & Conditions of
Deposition (Plates XXXVIUM-XILD) 100... eee 477

Wanps, Dr. ARTHUR. Some Observations on the Eastern Desert of
Egypt; with Considerations bearing upon the Origin of the
British Trias (Plates XITI-XVI)........... MP 8 os 6 cn 238

—. The Llandovery and Associated Rocks of North-Hastern
Montgomeryshire (Plates XXXITI-XXXVI) .............. 415

Watney, Miss G. R. (& Miss E.G. WretcH). The Zonal Classi-
fication of the Salopian Rocks of Cautley and Ravenstonedale

(Plate ayn Mae eee ele bi ecanes tei eee rele une 215
Woopwarb, Dr. ArTHUR SMITH. On some Mammalian Teeth

from the Wealden of Hastings ....)...- .. 0: 12-01. eee 278
Wootacott, Dr. Davip. The Stratigraphy and Tectonics of the

Permian of Durham (Northern Area)... >. 2 S7ocueeeeee 312

PROCEEDINGS.

Proceedings of the Meetings................... Mee se 1, XC1V
Aram UAL ARC DOLEY Vsesirvhescusiailersieaetene efste altace) ete) self. 9/004 Joke iesa\lele del eae 1X
Mistssof Donors to the wWitbrary) cts nlee ee oes ess eee Xill
distor Poreions Members) wes se iaaccoemenioe. kelsey ect XXIV
isto Horeienye orrespondentsaner ye eleliteie: eile et eee XXV

List ot. Wollaston» Medallists esrietvercttatclsts o's ecislete sieiereneiencnens XXV1

TABLE OF CONTENTS. Vv

Page
Persea arebisone Medallists). 6 2. cuuisc eid dees dele teleeans XXVlil
Permcumb yell Medaliistay bayer 0s uv. cede eb ee ee ee cea alas XXX
Lists of Bigsby é& Prestwich Medallistars. tcc2 is. oc eae aos oo SI
Applications of the Barlow-Jameson Fund and Awards from
pee Danie l=rdoecon PUM o.oo. ere eel Ok ae esis gie ee XxXxill
beter esa hue ODba) Set tan, ose, apnea anole epsteys ea 6 Sew a ou vials XXX1V
Peward.of the Medals & Proceeds of Funds ......-......~.. xli
Anniversary Address of the President ........0.-/.-s00e0e00: li
Royal Reply to the Address submitted to H.M. the King .... 1
Special General Meetings [disposal oi NINES UIT |<< fea tye = tare ete Vii, cli

Fauconer, Dr. James Dowie. [On the Geology of Northern
JING SET) ME Nato Gre cll) & te lam ene ne Wee gee Pare ema a xeVlli

JoNE&sS, (the late) THomas Ruprrr. {Announcement concern-
eat NMR TAN LUE a) eee siete s} 3) 3/2) 20°» o)44 scald ania oe Ss X¢Vil

Noposa, Baron Frrencz. [On the Geology of Northern

Exe NCAT EPA | ee SE OR oa ow cetih 2 n,"cha av te 60 shel eine aay’ XCiV
WarREN, 8S. Hazzuepine. [On a Paleolithic (?) Wooden
BS La eee ON les ae NN Soave euap oats ciakds whi wre « satay Matos & XC1X

Woopwarb, Dr. ArtHuR SmirH. [On Recent Excavations
ine C Otten ane eT seys| tl. ae ants aa ee yews ayaa asec ili

4

-LIST OF THE FOSSILS FIGURED AND DESCRIBED

IN THIS VOLUDIE.

Name of Species. | Formation. | Locality. Page
|
FORAMINIFERA.
Lepidocyclina elephantina...... | Aquitanian...... | Wadi Umzigga. 660
Nummulites curvispwra, } Middle Eocene .| Cyrenaica ...... | 659
BLO TOT NON afore stow owi tenes 6 |
Orthophragmina pratti .........; Hocene............ | Dernaleteinesas | 659-60
GRAPTOLITOIDEA.

Cyrtograptus rigidus, figs. 2 &| | f Wandale Hill, |
3 ae 4 : WEELOEE eons { CC? ea aceeereee | 234-35

Diplograptus (Amplexograp-| \ Trilobite-Dingle,

tus) perexcavatus, fig. 10 .. \ Shales ness | | N.E. Mont- 456

Monograptus vulgaris, fig. 11 .| | gomeryshire .
wandalensis sp. nov., aus Beds ... 456

LIA Ai eco s'il Sas wees Ue Wandale Hill..., 235-36

MADREPORARIA RUGOSA.

Amplexus (2 Spe; pl, fee \ |
GONCLIO OR ae enemas ut nee Gower s.qesee cee |: Saag
, Burrington
Caninia cornucopie, pl. xl, | | Combe &
ALS ea Neral ne sas cians ioe | | Stackpole 373-74
| | Qunaly © seer ce ‘
aff. cornucopie, pl. xl,| | ae
SSE OC nah taken. woke see | | § Gower .icesaaete 555-56
RG a Bie) || cAeVI@ MMA Toes jae |
cylindrica, pl. xxxi,| | |
stats LS Re oy Ae a a J Burrington 376-
patula, pl. xxx, figs. 5 a- | Combe)... 3.2
60 & text-fig. 11... | | 374-76
(Q) spon plex: tio me. ae | | SGOWers cd cee 556-57
Mi Opi: Xxxi, | | { Burrington | 974
Clisiophyilia, ls exacxd io eee y) H Clonal eee 0: || 380-81

FOSSILS FIGURED AND DESCRIBED.

Name of Species. | Formation.

| Locality.

MADREPORARIA RUGOSA (continued).

SOVGIRERONIG’ SP. .ccr.°-cs-~-+0- | \
Cyathophyllum murchisoni,
Perea ME OL aki aces
— (/) 0, pl. xxxi, fig. 2...... |
Dibunophyllum 9 & w, pl. xl,
PERRIN SoSp acts swe e Semennente te ots
Piphiyoh yllum sp., pl. xXxxi,
POMPEO Socodei oc sSecknteecsanics
Endophyllum burringtonense,
oP. noy., pl. xxx, figs. 4a- |

Michelinia konincki, nom. nov., |

PRPC MO AN, Cree sda bac
MEGUSTOMG —secececerserees
Streptelasma (2) aff. br eve, een
pl. xxxvi, figs. 20 & 21 ...... 1eGClS (Rea acood
Zaphrentis densa, pl. xxx,| \

OE eee ids ttiGic sc aaevaitnt as
enniskillent, pl. xl, fig. 2
oyster mouthensis, sp.nov.,

pl. xl, figs. la-le & text- VAVOMIAM 25 0:4h- |

HPN PO SA oe caicaine boc ecunedlocs |
cf. parallela, pl. xxx, |

figs. La-16 &(?) figs. 3a-

3b

Ce i i oe

} Avonian ......... |

| Burrington
|

Powis Park

| Burrington

Woamibei2sse.e |

Combes

| Burrington

MADREPORARIA PERFORATA.

Syringopora cf. geniewata ...| Avonian .........

ECHINOIDEA.

Amphiope aah v noy., pl.| | Slonta
Be NV I UMS OG Ow ciiinjsanineease J
Clypeaster oe var. |
trotteri noy., pl. xlvii, figs. |

Limestone ...

eer eee ck jan cens sos | ,
Echinolampas chericherensis, Cine Be
pl. xlviii, figs. la, 16, & 2, |
oll Scloc Sites Es eee
ere Operculina
Pewee ee eet ete ees eeeseens Limestone hs
EUSPALANGUS SPicc.cccccoeceseonss Aquitanian ......
EUGUlaria VUCiant ....ce0cvoenees Middle Eocene .
omiaster SCULE. z.ccassessh<sess Aquitanian, ete.
Hypsoclypeus hemisphericus ... Helvetian ......
Sarsella lamberti sp. nov., pl.
MVM tes. a @ Gi 3D oot. 70s. Megane
Schizaster ederi sp. nov., pl. eee
xlvii, figs. 4a-4c & text-fig.
Seutela tener ....cccceseeoeeees Lower Oligocene
2) US nea ee A Pe eee (?) Miocene ......

| Cyrenaica
Birlibah ...

|
|

1

{ Cyrenaica

\

eeeeae

eee tae

eee eee

Seeeeae

Vil

| 877-79

667-68
(662-64
}
1 669-71

| 666-67

Vili

Name of Species. |

Bairdia cf. ampla (2), pl. xxvii,
HIE et gb GS ABoocn de see aoo sdk Aohee

Otenobolinact. ciliata - XXXVI,
fig. 6

eee eereeeeeseee sess es serene

cf. an oy | oe ae 3
Jonesella crepidiformis, fig Qe
obscura, fig. 9 a

Be ocerereoseces

Krausella arcuata

eee eee e ese ereee

Loxoconcha cyrenaica sp. nov.,

text-fig.
Melanella hemidiscus, gen. et

sp. nov., fig. 9
Primitia tumidula
MUEGCD Nae cena Coie ck oe
Primitiella wnicornis, pl. xxxvi,

ecco eter eee sere eeecsoes

eee toceaeeecsece

figs, 4&5

Leaa leidyi, var. salteriana,
pl. xxvii, figs. 5 & 6

ee ee ee eee

ee eee pl. xxv, figs.
17/2116) ae See eenncoeadan Gouna
ns é 2) holocephalus, pl.
yp, WITS CEO Aa eee bac
sp., cf. guadrangularis,|
plex, igs id, We 1d:
Conocoryphe emarginata, var.

longifrons noy., pl. xxiv,
HUES tea 3 aa ea Re
Dionide sp. (2), pl. xxxvi,
TURN increas One Seciners orice eae

FOSSILS FIGURED AND DESCRIBED.

Dorypyge lakei sp. nov., pl. xxv, r)

figs. 1-8 & text-fig. .........|
Microdiscus sp., cf. punctatus, |
pl. xxv, figs. WTO
Paradoxides davidis, pl. xxiv,
fies. 17 a, 176, & 18 |
groom, pl, xxiii
rugulosus, pl. xxiv, figs.
14-16¢

i ie i ie i ee a ery

Pee ia aes “du-
bia sp. nov., pl. xxv, figs.
19 a-21 |

weet stereo eet n eee essere ne

) puichella sp. nov.,
pl. xxvi, figs. 1 @-2
= (SS) FD leh. jal seawi,|
OS ver Ca ONC wen cen ce eye
Trinucleus intermedius sp
nov., pl. xxxvi, figs. 1 & 2.

1

Formation. | Locality. Page
OsTRACODA.
} Coal Measures .| Bristol District.) 325
Gwern-y-brain N.E. Mont- sa
Shales .........| | gomeryshire . 452
Coal Measures . 4 Bristol District .| , 324-25
| 325
? H ? \ 451-02
Gwern-y-brain | { N.H. Mont-
Shallesivcrsase: | gomeryshire .| 453
} Miaate Eocene. Dernia .......0..-. 660-61
if (
| | | 451-52
| Gwern-y-brain 4 N.E. Mont- 4 452
f Shales ......... |} gomeryshire .| | 452
| || |
) Ae \ 452
PHYLLOPODA.
\ Coal Measures | Bristol District .| 825-26
TRILOBITA. |
| Lf | /
291
Py en | | 292
Me eae ap 4 Comley 17. iq
Beds eevee sees | | 9929-93
| | |
y) ru | | 286-87
\ Trilobite-Dingle
SIOENES soocdede. Guilsfield” ~ 3) )2005am
( ii
|| | 287-91
| | 292
|
| | | 285
| | : | 283-85
|
| Paradoxides | | 286
ding Bede 4 Comiley Panes ‘
| | 285
7 .
295-96
| | | 293-94
|
J ( | (295
Trilobite-Diugle! |
Shales Welshpool ......| 449-50

FOSSILS FIGURED AND DESCRIBED.

Name of Species. | Formation.

INSECTA.

Archimylacris spp. indet.,
pl. vii, fig. 2 & pl. x, fig. 3.
—— (Etoblattina) hastata sp.
Bev. pl. 1x, firs. }-3.........
—— (Schizoblatia) a
sp. nov., pl. vii, figs. 4-6 .
Genentomum subacutum sp.
nov., pl. xxvii, figs. 18 & 19.

|
|

a

Gerablattina (Aphthoroblat- |
tina) sulcata sp. nov., pl.| }Coal Measures .
CHIC esa] se |

Hemimylacris convexa sp. nov.,

VNU EEO! i ccisiesc cs vsiaine ces

——- obtusa sp. nov., pl. x,
nes, 2b a ee eer

Lamproptilia tenuwitegminata |
apenGys Plex fe. "6 2.22.2. |

Orthomylacris lanceolata sp.
nov., pl. x, figs. 1 & 2

BRACHIOPODA.
Acrothelect. granulata, pl. xxvi,| \ |
yet OVA tee ea |

Acrotreta (Linnarssonia) sagit-

talis, pl. xxvi, figs. l0a & TENSES

i) iad Pole Coa
aff. socialis, pl. xXvi,
ESN OOo. cnc scie svn o--|
Athyris (Cliothyris) globularis, if

eNO OG i. caaacsns oe. Amc e Re.

fi
Billingsella cobboldi sp. nov., )

pl. xxvi, figs. 20 a-23 |
——- lindstreemi var., pl. xxvii,| (ENS

1 edhe oe(/ deel 9) ee ee | { . Beds
,var. salopiensisnov.,| |
pl. xxvi, figs. 14a-17c¢ |)
Chonetes cf. buchtana.........--.| )

Gin COMIOIAES, of. oP das os sto. |

ef. crassistria |
— cf. hardrensis
——- ef. laguessiana ............)

sp., pl. xli, figs. 3a «|

+) roissyt, pl. sli,

a aa
ees eee

A eee veeee

ee i

a
oO
miofstateulalaleloinisteials elelaliateis > lols

ey

obtusiformis, sp.
pl. xxxvi, figs. 18 & 19

Lingula mytiloides Coal Measures .|

nov., | Gwern-y-brain |

J Shales

ee etee cere cence

if
:

|
'{ Clydach Valley .

|
en
|

Locality.

| \
if

Bristol D

|
| | Resolven

|
| Clydach Valley.

we

4 Comley

|

aoe

Comley

|

(
(
|
Combe

ee)
re

rae
—s
e)

-—_
Re

stock

Maes-y-cwmmer

istrict.

Maes-y-cwminer

| | Penller-gaer ..

Ce at

Serer eeee

Bristol (Avon) .

Burrington

| Page

:
1x

152-53
| 163-65

‘ 160-63

|

| 157-60
334-36

165-67
156-57
154-56
170-72
167-70

cS

ee
| 308
564-65

564
(
| 805

|
‘ 304-305

|

| 303-304
(381

| 382-83
4 382

| 382

\ 382

x FOSSILS FIGURED AND DESCRIBED.

Name of Species. |

Formation.

Locality.

Page

Bracutoropa (continued).

Lingulella cf. ferruginea,|

ple xxvi, Hes: D-6'0)..0.... 50.)
—— (2) spp. indet., pl. xxvi,

LOS A OO pcos tor een cod ace.
MGTAntG QUGOTE ..-.a. 0. cece. ee
Orthis (Orusia) cf. lenticu-

laris, pl. xxvi, figs. 24-26 ...
(2) sp., pl. xxvi, figs. 27 a
CORO EG rr Reece e ts eee er

Orthotetes cf. crenistria, pl. xli,} |

1S 8 le serrate on ee cen eee Meee
Productus sulcatus, pl. xhi,
fers’ ran Giese consi nant
(Marginifera) longi-
spinus, var., pl. xli, figs. 2a
GE OTe Sense e ae Sareea
Spirifer bisulcatus, var. oyster-
mouthensis nov., pl. xli,
GSO OMG) ects coe talon none
—- calcaratus, pl. xli_ fig. 5.
—— near iucrebescens, pl. xli,

wickensis sp. nov., pl. xli,

ITO aa nectar a tke sence ees

Spiriferina cf. octoplicata......

Syringothyrislaminosa,pl.xxxi,
oO

Bei Gs sere eee ncaa re cescereserns

|

Paradoxides

Beds ...

Avonian ...

eoeees

Paradoxides

Beds ...

MUNSON oop kaceon

LAMELLIBRANCHIATA.

Aiquipecten camaretensis, pl.
SINE ELGG UD) (se: Ob co naasnnnon ae

—— ‘cyrenaicus 8p. MNOV.,
jolly Sabiay titers, Ee ehangosa sara se
ck. deletus ...... Ree nities

hauert, pl. xliv, fig. 6
ef. pasintd, pl. xliv, figs. 4
(SGD) seSAbay CUS DA Aye aT OEM Oe

zittel?, pl. xlv, figs. 7&8.

al

Aquitanian

| Prioabnian

| Aquitanian

SCUUMOUME Sutera ye ete eee ndes |

y

Alectryonia cf. plicatula, pl.) \

SUT WO DML cece oes Sia tetcrartats
CPE UDMLCTUN ictus ie nso 8
Anadara cf. turonica, pl. xliii,

HVS aL VAR AG Aas Cisiate ceuactige tenia
Anthracomya lanceolata, pl.

RVUs and) dese ane cer
-minima, pl. xxvii, figs. 10-

COWL SO rauaaadecn dine ences

(CEU SCRIUGI'S) OI ahc ca ROPE ero

WULIAMSONG ....ecrecverees |
Canbontcol a Ss ...2eaneen «oan: y)

—

Helvetian-

Tortonian ..

Priabonian

ecceoe

$ Coal Measures .

oN

Pateley Bridge .

) Combe...

Cyrenaica

Ain Sciahat
Derna......
(

{ Cyrenaica

Bristol &
Radstock

lA

| Radstock...

eercee

e@eeces

eecees

eeeves

eeseee

| Bristol district .

Cyrenaica

300-301

301
564

306

| 562
562

562-63

563-64
| 384-85

633
644-45
644
(634
|
632
| 633-34
| 632-83

626-27
627

628
(
| 329-80

FOSSILS FIGURED AND DESCRIBED.

Name of Species.

| Formation.

Locality.

LAMELLIBRANCHIATA (continued).

Cardium tuberculatum .........
Cerastoderma cdule, pl. xliii,
ee AO... saadieagae asians
Corbis lamellosa, pl. xlv, figs. 12
Me cassis a s 27 casdionatisdeact
Glycymeris glycymerts .........
Jagonia pecten, pl. xliii, figs. 7
DE A ere io csiacieys oe coe cedtoice el
GRUPOS UOGLOUS 0. svecavsnacenes%
Inecina ef. nokbaensis... ........
Cle PUONAONIS oi peasiainsacs’
Meaveimigorn? Casts. .......0...-+.
Magctra ch. fOUTEAUL. wo. cec0004:
- Stulterum ..... se ee a ee
Naiadites elongata, pl. xxvii,
PARTE Lies eee dasorsiness oa vis.
ef. carinata, pl. xxvii,
HUME NME A) ccs ctarcasaisiioe sca
Nucula oblonga, pl. xxvii,

Sa

| Post-Pliocene..

| |
si Coal Measures .
Bristol district .

|
} Aquitanian

erent taees viccofasnde- )
Oopecten rotundatus, pl. xliv,| )
MES A) (cee niaolslelsicic basis
Ostrea cf. caudata, pl. xliv,
LG SL pe
—— erassi¢ostata, pl. xlv,| |
HG a a ee )
EI OMULUS os clue nain'enteasncetieneee
ef. ventilabrum, pl. xlv,
yD k0S = 1 Aa ae
sp. indet. ..... Moectede cee se

Pecten arcuatus, pl. xlvi, figs.

i er ird

—-— vezzanensis, pl. xlv, figs. 3

5, Ce Bo ala NE A ae
2

CMI ULE we eee aionGune

Pseudoedmondia (?) sp. nov.,|

Peeevi He LG ei score. eas as

| Sponds suns Bais pl. xliv,|

Hike ob ae een er ae ae
SSE eich Rea k eas osnnewitit
Trachycardium ef. granconense
Vulsella ef. cymari ....... 4065.
Bieri tec ccuertine eee kore
Ampullina crassatina............

Bellerophon (Protowarthia)
portlocki sp. nov., pl. xxxvi,
nV AGI Sl 6a ne Bea epee

Carinaropsis acuta, pl. xxxvi,
sO ls 2a be te ver

(

ie

Post-Pliocene ...!

Post-Pliocene...

Pwll-y-glo Beds.

| (Ptolemeta ......
‘+ Post-Pliocene...;

Benghazi.........

Slonta district .

Benohiaziy...... 0.
is
tre [ARMM see a corte

\ Cyrenaica ......

Benghazi.........

( Bristol &

Radstock......

Cyrenaica ......

Slonta district .| j

Bene Dazi.) a0).

Cyrenaica ......
Ain Sciahat......

Cyrenaica ......

Ain Sciahat......

Bemenagis crc... -
Radstock......... |

Ain Sciahat...... |
Slonta district .
| Mersa Susa......
Slonta district .

Merj district ...

Lamlucdeh ...... |

ae j N.E. Mont-

gomeryshire .

Pwll-y-glo ......

634-35
629-30

| 630
621
642
650

645-44
631-32

630-31
646
646-47
645-46
645

639-40

xi FOSSILS FIGURED AND DESCRIBED.

Name of Species. | Formation. | Loeality.

GASTEROPODA (continued),

L

Page

Cerithium cf. vulgatwm......... | 620
Chelyconus mediterraneus ...... (eeuaee: ...|4 Benghazi ...... | 621
Columbella rustica ........-+..-+. 620
Cyclonema donaldi sp. nov., . N.E. Mont-
ay xxxvi, figs. 7-9 e ee cise } Genin Cue gomeryshire .| 453
Cyrtolites parvus,var. carinatus| | Trilobite-
INO\iy jl zoORyily Hes Il © oaonde Dingle Shales.| Penbryn Dingle.| 455
TD eats Contigees T2| | Gwern-y-brain | (NB, Mont-
Ese An ee De Fin J Slvailesieeeeesere gomeryshire .| 454
Huspira ef. possagnensis, pl.
psclival pt ey DP as fete eos ace ae Peano y Cyrenaica ...... 638-39
COSORW OUaeNpEt, lk, “oan (Te !
TOMS Emer renin cecl sca annua \ Mersa Susa...... 640-41
Helicella tuberculosa, pl. xliii,
ISSO ic erisoeacicutnaens enue Data esens Benghazi......-.. 620
Hygromia sordulenta, pl. xliii, oe
IGE Tete 0 ae a geen ne aes 8 Derna district...| 619
Rostellaria sp., pl. xlvi, fig. 10.) _Priabonian ...... Cyrenaica ...... 640
Strombus cf. coronatus, pl. xliil. \ Helvetian-
LICH Hote ame ahe wetein ieicrsctetas Tortonian ...| ‘Gubabi...-22245 626
Vasum cf. frequens, pl. xlvi,
Lica Oy Svea hse namie MARE OM he no Priabonian ...... Missa) a. .ccictetiet 641
CEPHALOPODA.
Dimorphoceras (¢ discrepans) . \ ( ( 399-400
Glyphioceras beyrichianum ... | 400-401
Sa CLCHIUSEIIG, Syunerain a8 oa 406-407
(ICR USU SRS ANCRAe jeri eh SaNe OEE 403-404
OMOONSGUUS earacscoovoeennect | 404-405
= MULUDSY retailers cs sels s1soraleiete | | 405
TELICULATUIN ©... 000.2000 ens | 402-403
Sphericum ................... + Carboniferous...|{ Exeter District .|< 406
= GIUMUO Ssccteae od Beets es 407-408
SUPUOUCUMID Socontosodobdee-6s | | | 401-402
’ Nomismoceras spirorbis ...... 408
Orthoceras koninckianum ...... | 409
OUGUS UU ar inner, | | | 409-10
S)0) 0g Bg Goes adie Gan Be tee | 410
Prolecanites (2) sp. sese+.ss++. } ( | | 408-409
ELASMOBRANCHEI.
Ptychodus decurrens, pl. xvii,| \ (
fig. 2, & pl. xix, figs. 20-24. | Wanilousiis.coeee 264-65
var. depressus, pl. | Rochester
Saya WGC, kG CED poreadsdsot Gistricti eee 266
—— —— var. l@vis ............ : PERE mE. 267
—— var. multistriatus, pClealls ea Tae Bi (
pl. xviii, figs. 12-13, & pl. xix, | |
ASO, LOA ees sence | Tal WENO Seenocs 5. 4 267
- ——- var. owent, pl. xviii, | | |
fics 1211, & pl. xix, fig. 8...|} i ' | 266-67

FOSSILS FIGURED AND DESCRIBED. xlll

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

ELASMOBRANCHEI (continued).

Ptychodus dixoni sp. nov., pl. {\ ( |
Reres. .le Ait. Pesce cnn ce es : Rochester | 270-71
latissimus, pl. xx, figs. 3- district ......
ARE Ge eee | (270
—— mammillaris, pl. xxii, Cuxton & |
SON e vc d-icain cee tian stay. Betchworth.... 271-72
—— mortoni, pl. xxii, figs. 7 Winchester & —
& 8 Bere e rem eter eee reese esesesaseee H Chalk 4 Kansas weeree Vay as
ae polygyrus, pl. oon figs. i 24 if eee eee ewe ee |
Meals, Hes, I=. 2... | | WVANTOMS 18-5). -<05 268
var. concentricus . | Bene sazecuen 269
— var. marginalis, | | Rochester
pl. xxi, figs. 40-4¢ ......... | Lae Gustricg | oc: | 269
— var. silcatus.”........ her VartouS. 22.c.2-- 270
—— rugosus, pl. xxii, figs. 6 a | Purley &
ee J | Chatham......! 272
Mu tituBEerRcULATA.
Dipriodon valdensis sp. Boe | |
(EC) cine seh be | Ashdown Sands.) Hastings......... _ 279-80
INCERT# SEDIS.
Paleéoxyris helicteroides, pl. | Lower Coal |
mvt, Hes: 20:8 Dh). sis. | Measures...... Bristol district . 336
Fone.
Te QCACIMNG SP: kecnccsanecess +s | Aquitanian ...... | Wadi Uwzigga.| 659

EXPLANATION OF THE PLATES.

PLATE PAGE

( View or Bruz Ancnor Pornt; Forssuore Szcrion \
| NEAR THE FIRST GYPSUM- -WORKINGS ; UPPER AND
|; Lowsr Parts oF THE CLIFF AT Buve fee |
I-IV{ 9=Pornt; and Warren Farm Section, illustrating $ 1
| Mr. L. Richardson’s paper on the Rhetic and
Contiguous Deposits of West, Mid, and Part of |
\) HastiSomerset to. ot) pose daats <cet ee eee eee )

‘Map or Tie Permian AND TRrRIAg OF THE NorTH-
; | East or Eneuand, illustrating Dr. R. L. Sher- a5
, lock’s paper on the mutual relationship of those
| formations in Nottinghamshire ......... ...........

( SKETCH-MAP SHOWING THE EXTENSION OF THE EOCENE |
| AND OxigoceNe stRATA IN Heyrr, illustrating |
VI{ Dr. W. F. Hume’s paper on the Effects of } 118
| Secular Oscillation in that Country during the |
\ Cretaceous and Hocene Periods ..........0.--s.0.-0: y

( GERABLATTINA, ARCHIMYLACRIS, AND HzwIMyYLa- )
CRIS; GERABLATTINA (APHTHEROBLATTINA) SUL-
CATA ; ARCHIMYLACRIS (HTOBLATTINA) HASTATA ;
VII-X<{ and Orruomyzacris, Arcuimytacris, Laupro- + 149
priiiA, ete., illustrating Mr. H. Bolton’s paper |
| on Insect-Remains from the South Wales Coal- |

(Aiba (=) fo arene etree ke Merman ty chm seer GdnGt a ndctiocss sn )

{(Geotocican Map oF SkomEr IsLAND AND ae
XI ADJACENT PEMBROKESHIRE Coast, illustrating 17
Mr. H. H. Thomas’s paper on the Skomer f

Volcanic Series ian. ean eee aap aa a de

5)

GroLtogicaL Map or Tae Cautiey District, illus-

XII trating the paper by Miss G. R. Watney & 915
| Miss E. G. Welch on the Salopian Rocks of
Cautley and Ravenstonedale ....................000-

(ein Iv THE Um Es Rance; VIEW FRoM THE )
SUMMIT OF A GRAVEL-TERRACE, AND LIMESTONE

Fretrep away By WInpD-BLOwN SAND; CoarsE |

: SAND WITH MINIATURE DREIKANTER AND Wutts |
XITI-XVI 4 Limestone Cuirrs, JUBAL Isuanp; AND Brock [ 238
oF WEATHERED GRANITE AND ARROWHEAD Twin
or Gyesum, illustrating Dr. A. Wade’s paper on
the Hastern Desert of Hey pb assscesssenace- cee )

PrycHobus potyeyrus ; and Tretu or Prrcno-
DUS POLYGYRUS, Pr. MAMMILLARIS, Pr, RUGOSUS,
AND Pr. morront, illustrating Mr. G. 5. Dibley’s |
paper on the teeth of that genus............... “scene

CHODUS DIXONI AND Pr. LaTisstuus ; TEETH OF

263

|
\
(Teta or PrycHoDUs DECURRENS ; 'TRETH oF Pry-
|
|
XVII-XXIT +
|
|
(

——e ee ies) st

EXPLANATION OF THE PLATES. XV

PLATE PAGE

( PARADOXIDES GROOMI; PARADOXIDES, ETC., FROM )
ComLEY; CAMBRIAN TRILOBITES FROM Comey ; |
XXITI-XXVI{ and Camprian TrILoprres and Bracnrorop ps} 282
| From Comipy, illustrating the paper by Mr. E. S. |
| Cobbold & Dr. C. A. Matley on those fossils...... |

’ Marine Fossizs From tre Brrsron CoaAL-Mnrasurgs,
XXVII illustrating Mr. H. Bolton’s paper on anna | 316

| Herizons in the Bristol Coalfield ........ Soe atne }

( Microscope Rock-szerions ; and Avontan Corats \

| FROM THE BurrineTon Sscrion (Manpip), wits |
XXVITI-XXX{f{ one Bracutopop, illustrating the paper by Prof. } 342

| S. H. Reynolds & Dr, A. Vaughan on the |

Nerv Avounam: of theta loealiby 2p .c.sss.0- sage cececsseacoe sn )

pemougaes: SKETCH-MAP OF THE Exerer Disrrict,
XXXII illustrating Mr. F. G. Collins’s paper on the + 393
| @ulmavo hima area Ayr ae edltiaactee te ocanonaees ler

(GroLocicaL MAP OF ‘THE NEIGHBOURHOOD - OF \
| WELSHPOOL; QUARRY-SECTION IN THE BuTrinc- |
TON SHALES; Igneous anp Fesparuic Frac-
| ents iv THE Upper GArrrawr GRIT, AND THE | p
OTT XVI 4 WexsHpooL Dyke; Upernr OrpovicrAN AND r =
| Lower Siuurran Fossius, illustrating Dr. A.
Wade’s paper on the Llandovery and Associated |
Rocks of North-Eastern Montgomeryshire ...... )

(
Rocks FRom THE MoNnMOUTHSHIRE MoNncHIQUITE-
XXXVIT Dyxe, illustrating Prof. W. S. Boulton’s paper } 460
Ghia OC Kater: coe he Ae ak ee es, aul 2 ai ‘

(‘ Pirrep’ Limestone and Unpo.omitizep Psuupo- \
| Breccia; Parrity DoLtomirizeD PsEuDoBREccrs ; |
: | Avontan CoraLs FROM D, anp D,—-D,; Avontan |
XXXVITI-XLI 4 Bracuiopops From D, Sis illustrating the paper r ad
(oe by Mies By BE. Dixon and Dr. A. Vaughan on the |
-)

| Carboniferous Succession in Gower .............

{ GpoLogicat Map or Cyrenatca and SECTIONS FROM )
| Beneuazi TO Derna AND From THE Moers Fautr- |
XLII{ scarp ro THe Sea NEAR Proxenera, illustrating }
j
|

On
=~I
bo

Prof. J. W. Gregory’s paper on the Geology of |
Uy DeGIEE NICE ee eee tern aise ye oo ok Pes Seana Rams }

iS me { Kartnozoic Mou.usca FROM OyrENAICA, illustrating
aa Mr. R. B. Newton’s paper on those fossils ..... :

op)

16
3 Fossit EcntnoipEa FROM CYRENAICA, illustrating :
a Prof. J. W. Gregory’s paper on those organisms. a: por

‘ SKETCH-MAP SHOWING A PorTION oF THE GREAT
i ANTILLEAN Distocation, illustrating Mr. R. J.
L. Guppy’s paper on the Geology of Antigua

and other West Indian Islands ............... .....

681

GEOLOGICAL Map oF THE NEIGHBOURHOOD OF Wor-
LI CESTER (Cape Cotony), illustrating Mr. R. H.| .
Rastall’s paper on the geology of that and other
districts of CapewWolomy 0.6... viccceses eset cecoee

Xvl1 FOLDING TABLES.

FOLDING TABLES.
Page
TABLE ILLUSTRATING THE CORRELATION OF THE ORDOVICIAN AND SILURIAN
Rocks oF Nortu-Eastern MonrGoMERYSHIRE WITH THOSE OF
OTHER ARHAS) facia ees sceseeeeeee ce bap eserss sence cee 446

TaBLE I.—-Synopsis oF THE LitnoLoGicaL SEQUENCE IN DIFFERENT PARTS
On Gownr, facinecr yrn-cetn dee see cece caicist vane ane RRR oe: 505.

PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES,

Fig.

Or

BESIDES THOSE IN THE PLATES.

PaGE
View of Cleeve Bay, sues towards the North Hill, Mine-

eee ae 23 eet saan HR INE DS ale ORR a alicia wees ase tka 13
Sparkford Hill section (diagrammatic) ...........2.....0sscceosscees 44
Map showing the positions of the quarries at Sparkford

Ean Camel Eine ae eo Se Ie tot asB ie ke een noes 44.
Diagrammatic section of the quarry at Fivehead ............... 52
Geological map of South Nottinghamshire ........................ 78
Section of the Great Central Railway between Annesley and

oricby-tm Aum titel dh) 6.52 1 36 on cane ame eess wo oeasatok deca - 80
Section at Messrs. Lindley’s ‘ White Sandstone’ Quarry, Mans-

TT A, EEO 40 EEC a 2s re er ee ee 87
Diagramuatic section across the Permian at Mansfield ......... 90
Diagram to illustrate the formation of the Mansfield ‘Sand-

STUPID ads ap Pra ar Oar Pa Ee SPIN? AB a a ae ea 90
The sandpit of the Mansfield Sand Care eeey: Ltd., Berryhill,

NUESDE TENS. UE Geee omep ee eceebr Sect) okadaic eee ape einPeP ReneS 92
The south-western coast of Skomer Island, seen from Skomer

NEU AGY Flee eo facia atin anes Se ne Ee ce dot eVawes ou chien wesine 176
[Vertical sections.] Anvil Bay & Jeffry’s Haven.................. 181
[Microscopic sections. | Soda-rhyolite OLISKOMECEE if) cocapies fees 186
Nodular rhyolite of the Basin, Skomer ..................0008. sea Bege 187
[Microscope-sections.] Pseudomorphs after augite in chlorite,

Ne ee I IN else arene ce onde oe ope aalk doit nld sone at 188
[Microscope-sections.] Albite-trachytes of Skomer ...... 191, 193
[Microscope-sections.] Keratophyres of Skomer.................. 194
[Microscope-sections.] Skomerite and mugearite ............... 197

VOL. LXVII. b

XVill

Fia.

2&3.

PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES.

[Microscope-sections.| Marloesite and antelledte aaa 198
[Microscope-sections.] Olivine-basalts of Skomer ............... 203
[ Microscope-sections.| Ophitic dolerites of Skomer ............ 206
Diagram illustrating the percentage chemical composition of

the Skomer igmeous rocks) 25.0.0 .02- ees. +--+ ++ +c e eee 209
Section through Wandale Hill ya calarat ree , sete det ewes OSE eee 224
Contograpius rig¢a is MiG Ree eee nee tec 4. «ica. eee err eee 235
Monograptus Wandalenstsn Sp NOV eo) .: <cc.sie sce ace oes e eee eee 235

Map of Egypt, showing the distribution of the ‘ gravels’ con-
taining igneous rocks derived from the Red-Sea Hills......... 243

Sand with ‘dreikanter,’ from the sandy gravel-plains north of
the ‘Gulf. of Denisa. fe 2 ee cae oso reelane ese. Saded a ikeia, eee 246

Foraminiferal sand, southern shore of South Gaysum Island... 247

Geological sketch-map of part of the Red-Sea area ............... 255
Meeth of Dipriodon valdensis, sp: WOV. <2eenaa: sees. 4se secs aeeeeeee 279
Side view and view from above of Dorypyge lakei, sp. nov. ... 291

Section of the Bristol Lower Coal-Measures, from the Ashton
Great Vein to the Bedminster Great Vein...................0000: 318

Map of Burrington Combe and the immediate neighbourhood 34

Section in the bed of the eastern twin stream [Burrington

Oomibel] cccniccncii ce. sete ities dale sack anaes lates cen eee 350
Hillside between Quarries 1 & 2and the upper part of Quarry 2

[Burrington, Combellc....0. acest oicectecancinnye sence ee eee 304
From the hillside exposure of 8, past Quarry 2 and Plumley’s

Den to *Che'Caver)|[burrimegton)Combell <7. .-------c seer 305
S, and C, beds, from Quarry 2 to near Quarry 3 [ Burrington

Combe Pita eo ea teehee aateee nae gee onpnee dc danaea hea eee 356
The base of C,, the dolomites of Quarry 3, and the top of O,y

[ Burrington Combe ie os5. ccs abou-n ac -esccneseccaeee eee 357
View reversed, looking northwards [ Burrington Oombe]......... 358
The great scarp of C,y | Burrington Combe]...................0005- 309

Valley of the western twin-stream and the great scarp oeyond
it [Burringtont@omibel|ieencc-sces-s: eases soeee eaten oe aeee eee 360

Looking up the valley of the western twin-stream [Burring-
» tom: Combe] ine eetumneb se ceeeten alt liccaus dae sname: here eee ae 361

Contoured plan of one of the characteristic tabule of Caninia
patil, MACH S cect oar maced actu wadeaktaenees samedi eee deat ee eee 375

[Vertical sections.]| The relation of Burrington to other
Carboniferous Limestone districts ................ccsceeeeneeeeeees 386

Phy Seat)

10.

11.

9 & 10.

PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES. x1x
PaGE
Section from Penbryn Dingle to Trefnant Dingle ............... 420
Section exposed in Gwern-y-brain ..............--ssseeeseeeeee rece ees 422
Section near the top of Gwern-y-brain Valley ..................4:. 428
Section reproduced froma Murchison’s ‘Silurian System’
ICS ®), 70. BOL ec dnostohesorsoonbab peecosbeaneUoeneceNasoe sudzoc eae BEER se 431
Map illustrating the exposures in Cwm Caethro.................. 437

Map showing the Wenlock zones exposed in Guilsfield Brook. 438

Generalized section from east to west, illustrating the structure

of [part of North-eastern Montgomeryshire] ................-. 443
[Microscope-section.] Bostonite of the Welshpool Dyke ...... 447
Jonesella crepidiformis, J. obscura, and Melanella hemidiscus,

SETI EL ISP MOVs) cclestsce jae tener sede fctecee encom ie-Wsie=amcincen niece 452

Amplexograptus perexcavatus, Lapw. ......ceeersersesseseeseescowees , 456
Young form of Monograptis vulgaris ....csrcoeeeseseereersceeensenees 456
Map of the neighbourhood of the Great House, Golden Hill

(bomen @nntsliKS TWR®)) Lode eonoopetconegocescoucdccobaicsececeandeanoensonee 461
Fine-grained Old Red Sandstone at the contact with the

FTTOMNG COUT i eeimodec ache he HED NOR AR EEE JADA Car Eh aon Daa na Ar aCe ce aorA caine 463
[ Microscope-section showing various parts of the monchiquite-

Give tee ie e islectl ih S su! ack docu ibe isuatameaue eee ecese lads eas 467
Topographical map of Gower and related areas ................2. 478
Gealomeali may Ol Gower y..ci)/ccencacsecupen sactincsecs vases eslatoessaee 479

D,_, limestones and shales in the ‘Black Lias’ Quarry at
Oy stermioub My es pe cas. » tu sree etaceeranclise mane ee delsuvasieatescarces 492

Comparative vertical sections through the Avonian of Gower . 506

Diagram showing the relation of the dolomite in a partly-
dolomitized pseudobreccia, to unrecrystallized calcite......... 510

Ideal section across a lagoon-area at right angles to the coast . 512

Diagram showing the probable relations between the uncon-
formities at West Williamston and Pendine....................- 527

Diagram showing the variation in depth of the Avonian Sea at
successive times, deduced from the sequence in Gower ...... 533

Zaphrentis oystermouthensis, sp. NOV.........0.0eceesecsenceenee 504, 555

xx PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES.

Fra. PAGE
1. Section drawn southwards from a point about 6 miles south-

Gast Of Dernajcc..icecsecvcesetesh tet oere veeet stesso 579

2. Section in the plateau-face at Wadi Nagr, west of Derna ...... 581

3. Section from Sionta through Cyrene to the sea ...............06- 584

4. Sketch-map illustrating the tectonic relations of Cyrenaica ... 604

— Loxoconchaicyrenatead, sp. MOV. <...2..-.5.-.- +2... 0-287 ere eee 660

— The granulation of the anterior ambulacral plates in [ Schézaster

TUNOSUS ANG SCN. (COC SP sgMOVA| ses2e-4---: <<< eee sah Wont 674
1. ‘Quthne-map: of Antigua s25 oaacce se aecee edie ses eee 6883
2. Diagrammatic sections across the Antillean Dislocation ...... 689

3. Diagram of strata originally exposed at ee Mount

(Barbados) i etebivaeniwieneb in ila we donde Chedtns wre dns te era 694
4, Diagram showing the position of the Orbitoides Bed beneath

the Naparima Marls) Mrinidad’ 22h. s2 sec eee 697
1. Diagrammatic section from Worcester to the foot of the

Hlex-River Mowitains 2 2 56s-cnsssce-cee ceteemene eee eee 705
2. Diagrammatic section through the southern part of the farm

De TROOP | a. hee es eea Ui acne See en sa aen ones ocle cones eee Ree 721
3. Geological map of the district round Montagu and Ashton ... 722
4. Diagrammatic section along the banks of the Kogmans River . 723
5. The dominant trend-lines of the south-western part of Cape

GOlOMY \ ii Meee cdan donne eatenneee sent. tinnorvelne settee 726

ERRATA.

Page 272, lines 6 & 26 from the top, and Page 275, line 4 from the bottom,
for ‘ testitudinarium,’ read ‘ testudinariwm.’

Page 341, line 40 from the top, for ‘ Genentonum,’ read ‘ Genentomum.’

Pages 451 & 452. Fig. 96 alone represents Melanella hemidiscus, gen. et
sp. nov. ; and fig. 9 @ represents Jonesella obscura, Ulrich.

LL LOLOL OL OLD OI ODO ODN ODNOWIENIE Om hE OOO ameEmyanm eae aaa eee

Vol. LXVII. FEBRUARY, 1911. Wo. 265.
Part 1,

THE

OF THE

EDITED BY \ ——

\ANetions Miu‘
THE ASSISTANT-SECRETARY. ~~}

[ With Ten Plates, illustrating Papers by Mr. L. Richardson,
Mr. R. L. Sherlock, Dr. W. F. Hume, and Mr. H. Bolton. |

LONDON :

LONGMANS, GREEN, AND CO.

PARIS:—CHARLES KLINCKSIECK, 11 RUE DE LILLE.

~

SOLD ALSO AT THE APARTMENTS OF THE SOCIETY.

Price Five Shillings.

ACI RRA AA rn nen en nnn nesses eee kk keke _ kk ll ll _ ll ll _ eel eels es
eee

[Issued March 17th, 1911.]

LIST OF THE OFFICERS AND COUNCIL OF THE
GEOLOGICAL SOCIETY OF LONDON.

— Oe

Elected February 17 Ene ouels

La ewe

President.
Prof. William Whitehead Watts, Sc.D., M.Sc., F.R.S.

WtcesPrestVents.

Charles William Andrews, B.A., D.Sc.,
E.R.S.
Alfred Harker, M.A., F.R.S.

John Edward Marr, Sc.D., F.R.S.
Prof. William Johnson Sollas, LL.D.,
Se.D., F.B.S.

Secretaries.

Prof. Edmund Johnston Garwood, M.A.
Foreign Secretarp.

| Arthur Smith Woodward, LL.D., F.R.S.

Creasurer.

Sir Archibald Geikie,K.C.B.,D.0.L.,LL.D., | Aubrey Strahan, 8c.D., F.R.S.

Sc.D., Pres.R.S.

COUNCIL.

Henry A. Allen.

Tempest Anderson, M.D., D.Sc.

Charles William Andrews, B.A., D.Sc.,
F.R.S.

Henry Howe Arnold-Bemrose, J.P., Sc.D.

George Barrow.

Prof. Thomas George Bonney, Sc.D., LL.D.,
FERS.

Prof. William 8. Boulton, B.Sc.

James Vincent Elsden, D.Sc.

John Smith Flett, M.A., D.Sc.

Prof. Edmund Johnston Garwood, M.A.

Sir Archibald Geikie, K.0.B.,D.C.L., LL.D.,
Se.D., Pres. B.S.

Alfred Harker, M.A., F.R.S.

Robert Stansfield Herries, M.A.

Bedford McNeill, Assoc.R.S.M.

John Edward Marr, Sc.D., F.R.S.

George Thurland Prior, M.A., D.Sc.

Prof. Sidney Hugh Reynolds, M.A.

Prof.William Johnson Sollas, LL.D.,Se.D.,
E.R.S.

Aubrey Strahan, Se.D., F.R.S.

Herbert Henry Thomas, M.A., B.Se.

Prof. William Whitehead Watts, Se.D.,
M.&c., F.R.S.

Rev. Henry Hoyte Winwood, M.A.

Arthur Smith Woodward, LL.D., F.R.8.,
F.L.S.

Assistant-PSecretarp, Clerk, Librartan, and Curator.
L. L. Belinfante, M.Sc.

Assistants in @ffice, Ltbrarp, and Museum.

W. Rupert Jones.

Clyde H. Black.

Arthur Greig.

STANDING PUBLICATION COMMITTEE.
Prof. W. W. Watts, President.

Prof. E. J. Garwood,
Dr. A. Smith eae ce Secretaries.

Mr. H. A. Allen.
Dr. C. W. Andrews.
Dr. J. V. Elsden.
Dr. J. S. Flett.

My. A. Harker.

Mr. R. S. Herries.

Dr. J. E. Marr.

Dr. G. T. Prior.
Prof. S. H. Reynolds.
Prof. W. J. Sollas.
Dr. A. Strahan.

Mr. H. H. Thomas.

EVENING MEETINGS OF THE GEOLOGICAL SOCIETY
TO BE HELD AT BURLINGTON HOUSE.

Sesston 1910-1911.

tae
Wednesday, Wanchyc3 toi viper arses: 22
As JN OVINE Raa REO Aaa ians. 5* —26
4 Mia ying ser nenccrate se 10*—24
y CUMS ANS arene 14*

[| Business will commence at Fight o Clock precisely. |
The dates marked with an asterisk are those on which the Council will meet.

THE

QUARTERLY JOURNAL

OF

THE GEOLOGICAL SOCIETY OF LONDON.

Vout. LXVII.

1. The Rumtic and Coxtievous Derosirs of West, Min, and Part
of East Somerset.” By Linspatt Ricwarpson, F.R.S.E.,
F.L.S., F.G.S. (Read November 9th, 1910.)

[Puatzs I-IV.]

ConTENTS.
Page
APG NO MMCLIOM jee: 2. tee ee oes: sleet salsa sede nanet vs 2
II. Subdivisions recognizablein the Rhetic Rocks of the
Districirdescribed): ys... 263.002 Re. Ph Aree SORE ee
PRE eR aM Sy se pear ate et ees pies te slides aiahiace Sle li
Gi) Wiest Somerset, 60180 s.c0 0.0 tte eignk sos eek oy 11

(A) The Selworthy Outlier.
(B) The Watchet Area.

(ZyPRB di SOmersebs. ieee eae sce ee emel sea en nlenmign via: aes 31
(A) The Polden-Hills Area.
(B) The Sparkford-Hill Area.
(C) The Somerton-Langport Area.
(D} The Langport-Howley Area.
(E) The Wedwore Inlier.
(F) Lhe Uphill-Shepton-Mallet Area.
(3) pBass SOMeRSEi (POTS) ea nacre. saekudgs cd esms snes 61
(A) The Nunney-Elm Area.
(B) The Radstock Area.
(C) The Stone-Kaston Outlier.
(D) The Hinton-Blewet Area.
(EK) The Harptree Area.
(F) The Nempnet Outlier.

1 In this paper, by ‘ West Somerset’ is meant Somerset west of the Tone
and Parrett; by ‘Mid Somerset,’ the portion between these rivers and a line
running from the coast at Bream Down along the Mendip Hills to near
Downhead, and then turning southwards; while ‘ East Somerset’ is the
remainder of the county.

Q. J. G. S. No. 265. B

2 MR. L, RICHARDSON ON THE RHETIC OF [ Feb. roma,

I. InrrRopvuction.

In Somerset the Rhetic rocks have a greater superficial extent than
in any other county. It was anticipated that their investigation
would prove of exceptional interest for several reasons: notably

because—
(z) It has long been known that the Series attains an unusual thickness in
places in this county, while it also frequently assumes a littoral facies

when in contact with the Paleozoic rocks that formed .land-areas
during its time of deposition ;

(0) The discovery in the top-portion of the ‘Grey Marls’ of Watchet of
Microlestes teeth, associated with characteristic Rhetic fossils, has long
been an important fact in the discussion as to whether the ‘Grey and
Tea-green Marls’ (auctt.) should be classed with the Rheetic or with the
Keuper ;

(c) The Pteria-contorta Shales, with their associated hard beds, have yielded
a rich assemblage of invertebrate fossils ; and

(d) The White Lias is excellently developed, and its relationship to the
Lower Lias can be studied in many sections.

In order, however, that students of the Series should have at
their disposal easily-comprehended facts concerning the detailed
stratigraphy, as also a knowledge of the position of certain strata
bearing well-known names, and the horizons whence many of the
well-preserved specimens now housed in our museums came, much
detailed work was necessary. The main points that required to be
settled were :—

(a) The stratigraphical position of the marls that had yielded the MWicrolestes
teeth and other characteristic Rhetic fossils;

(@) The true position of the ‘Wedmore Stone,’ Moore’s ‘Flinty Bed,’ and
the Pleurophorus Bed ;

(y) Whether the ‘Upper Rhetic’ as developed, for example, at Garden
Cliff, near Gloucester, is represented in Somerset ; and

(5) With which formation the White Lias proper is best classed—with the
Rhetic, or with the Lias.

In addition to the record of a number of new or imperfectly
described sections, my researches have resulted in showing that :—

(a) The Microlestes Marls correspond to the Sully Beds of the Glamorgan
coast, and are well-developed in West Somerset ;

(8) The Pteria-contorta Shales are of greater thickness than has generally
been supposed, and contain, especially below the Plewrophorus Bed (13)
and the main Bone-Bed (that is, Bed 15), some highly fossiliferous
bands ; that the ‘ Wedmore Stone’ occurs well below the equivalent
stratum to this main Bone-Bed (Bed 15); and that Moore’s ‘ Flinty
Bed’ of Beer Crowcombe (or ‘Crocombe’ as it is now spelt) is most
likely on the horizon of the Plewrophorus Bed (13);

(y) The ‘ Upper Rheetic,’ as defined in my previous papers, is as persistent
as usual, if not quite so thick ;

(0) The White Lias proper is of considerable thickness in places, is in its
characteristic development of comparatively restricted geographical
extent, and is best classed with the Rhetic; and

Vol. 67. WEST, MID, AND EAST SOMERSET. 3

(ce) That the marly beds above the White Lias proper, which correspond
to similar marly beds at Lavernock (where they were provisionally
grouped with the equivalent of the White Lias proper), are worthy of
separation and distinct designation.

Indeed, it has become increasingly evident that, in order to be
able to set forth clearly the changes in lithic structure which the
Rheetic Series undergoes from place to place, and to convey to the
palzontologist a knowledge of the horizons whence the fossils with
which he may be dealing came, certain new stratigraphical terms are
essential. These are discussed in a later portion of this paper.

(i) Geographical extent of the Rhetic Series.—The
Rheetic beds have a greater superficial extent in this county than
in any other, and their distribution is best seen upon reference to
the Geological Survey maps.

Gi) On the lower and upper limits of the Rheatie
Series.—In the Midland Counties the line of demarcation between
the Keuper and the Rhetic is sharply defined’: the Tea-
ereen Marls are succeeded suddenly by the well-known Black
Shales. But in West Somerset, and in the Lavernock district
on the opposite Glamorgan coast, there are, between the Tea-
green Marls and the Black Shales, ‘Grey Maris’: real
* passage-beds,’ for dark bands occur in them at more than one
horizon and in their uppermost 14 feet or so—as Prof. Boyd
Dawkins long ago pointed out *—characteristic Rhectic fossils make
their appearance. [or these top 14 feet of fossiliferous Grey
Marls I have suggested the name of ‘ Sully Beds.’ °

Although the gap between the Tea-green Marls and the Black
Shales on the Bristol-Channel littoral is thus to a considerable
extent bridged over by the intervention of the Grey Marls* and
Sully Beds, there is still a non-sequence at the top—between the
Sully Beds and the overlying Black Shales. The upper surface
of the Sully Beds at Lavernock was deeply channelled before the
deposition of the Black Shales’; while, both at St. Mary’s-Well
Bay (Sully) and at Lilstock, the top-layer of the Sully Beds is a
thin band of impure limestone, practically made up of specimens of
Pteria contorta, thus betokening slow formation. It is also inter-
esting to note that other portions of the Sully Beds afford evidence

1 BR. Wilson, Q. J. G. S. vol. xxxvili (1882) p. 455; and Proc. Bristol Nat.
Soe. ser. 3, vol. vii (1893-94) pp. 218 ez segg.

2 Q. J.G.S. vol. xx (1864) pp. 397-98.

3 [bid. vol. lxi (1905) p. 386.

4 Tn this paper the term ‘Grey Marls’ means those deposits, less the fossi-
liferous top-portion or Sully Beds. The term ‘ Grey and Tea-green Marls’
means the Grey Marls, as thus defined, plus the Tea-green Marls, and in the
record of a section indicates that I think that both those deposits in part or
wholly are represented ; while the usage of the term ‘ Tea-green Marls’ alone
implies that I think that there are no Grey Marls represented -—only Tea-green
Marls.

> Q. J. G.S. vol. lxi (1905) fig. 1, p. 390.

BZ

4 MR. L. RICHARDSON ON THE RHZTIC OF [Feb. 1911,

of slow formation, for Prof. Boyd Dawkins speaks of marks resem--
bling sun-cracks and annelid-tracks in what I identify with the
Sully Beds on the Watchet coast.*

So far as can be deduced from a study of the lithic and faunal
characters of the lower beds of the Black-Shale division and their
relationship to the Keuper Marls, the area of sedimentation in
closing Triassic times seems to have become continuously smaller
and to have been situated in the South-West of England. The.
commencement of the changes in surface-level, which initiated
Rhestic conditions, are probably indicated by the occurrence of
black marls in the Grey Marls; while, just before crust-movements.
effected the restriction of the area of sedimentation to the neigh-.
bourhood of the present Bristol-Channel littoral, the pioneers of the
Rhetic fauna must have obtained entrance. Their scanty remains.
are preserved in the Sully Beds, and the period of minimum sub-
mergence is probably marked by the runnelled surface of the Sully
Beds and the closely-packed layer of specimens of Pteria contorta..
Gradual submergence then set in, and the neighbourhood of the
present Bristol Channel received the earliest deposits of the Black-.
Shale division.

Thus, while over the greater part of England the lower limit of
the Rheetic Series is sharply defined, because the Sully Beds.
and a greater or less thickness of the Black-Shale
division are absent, and there is therefore a non-
sequence, on the Bristol-Channel littoral it is most unfortunately
indefinite—being determined by the downward range into the-
Grey Marls of Rhetic fossils. For scientific purposes, the Sully
Beds must be grouped with the Rheetic; but for cartographical.
purposes—as I have before endeavoured to make clear *—they
must be grouped with the Keuper Marls.

As regards the upper limit of the Rheetic Series, in most parts of
the South-West of England it is fairly definite. The Lower Liassic
beds which are generally grouped together as the Ostrea Beds are.
readily recognized, and underlying them is often present a band of
hard ‘paper-shales.. The Paper-Shales are not always present ;.
but the Ostrea Beds have a wide geographical extent, and rest in
different places upon different members of the underlying Rheetic
Series. ‘Thus, near Wickwar, they rest upon the Cotham Marble ;.
but in the Charlton-Mackrell district there is very clearly interposed
between them and the Cotham Marble the White Lias proper; at
Blue Anchor Point in West Somerset, both the reduced equivalent
of the White Lias proper and certain marly beds (* Watchet.
Beds,’ see p. 15) above; while at Camel Hill, Moore’s Insect- and
Crustacean Beds come in at a higher horizon.

There is thus generally a non-sequence between the Rheetic and.
the Lias, which implies that, as a rule, the two series are well
marked off one from the other.

1 Q.J.G.8. vol. xx (1864) p. 398.
2 Ibid. vol. lxi (1905) p. 414; and Proc. Geol. Assoc. vol. xix (1906) p. 403. .

Vol. 67.] WEST, MID, AND EAST SOMERSET. 5

Il. SuBDIVISIONS RECOGNIZABLE IN THE Ru a#ric Rocks
OF THE DISTRICT DESCRIBED.

The beds that lie between the Keuper and the Lias constitute
the Rheetic Series. The Series admits of dual division—into Upper
and Lower Rheetic.' The Sully Beds and Black-Shale subdivision,
or the ‘ Zone of Avicula [| Pterca] contorta’ of earlier authors, con-
stitute the Lower Rhetic; while the ‘Upper Rhetic’ of my
previous papers, the White Lias proper and certain immediately-
superincumbent marly beds (‘ Watchet Beds,’ see p. 8), compose
the Upper Rhetic as now defined. These two primary subdivi-
sions are very distinct one from the other, both as regards lithic
structure and as regards faunal characters.

Lower Rhetic.

Sully Beds.—Concerning these beds almost sufficient has been
said. The essential points to remember are that in reality they
are only the topmost 14 feet or so of the Grey Marls that
contain Rhetic fossils.” Their upper surface in places shows
evidence of channelling by water previous to the deposition of
the Black Shales, and this fact—among others—points to a non-
sequence, which largely explains the difference in appearance
between the Sully Beds and the succeeding Black Shales.

Westbury Beds.—This term is suggested for use, as an
alternative term to ‘ Black Shales,’ etc.

The Westbury Beds vary considerably in thickness in this
country: at Berrow Hill, near Tewkesbury, they are but 9 feet
thick; at Lilstock, 32 feet; and at Blue Anchor, near Watchet,
they may be as much as 46 feet thick. In other localities they
are thinner, but nowhere thicker. It is interesting to note that,
where the Westbury Beds are thick, so are the subjacent Tea-green
Marls or Tea-green and Grey Marls, and vice versa.

The Westbury Beds were deposited not far from the coast-line,
for this is shown by their Swabian or littoral facies. The mollusea
have a dwarfed appearance: gastropods are abundant in certain
beds in Somerset, and in the sandstone of Pylle (Glamorganshire)
specimens of Natica abound; pieces of lignite are not infrequent
in some of the beds in Glamorgan and Somerset ; and, except for
Orbiculoidea townshend: (Forbes), brachiopods are wanting.

_1 [Certain other terms were suggested for these subdivisions when the paper
was communicated (see Discussion, p. 73); but, in deference to the wishes of
the Publication Committee, those terms are not used here. |

2 In places in West Somerset Prof. Boyd Dawkins also found characteristic
Rhetic fossils in some abundance in the Grey Marls that are now correlated
with the Sully Beds. (Q.J.G.S. vol. xx, 1864, pp. 397 e¢ segq.)

6 MR. L. RICHARDSON ON THE RHZTIC oF _——[ Feb. 1911,

Roughly speaking, the Westbury Beds can be separated into
two parts, an upper and a lower, according to the occurrence of
vertebrate and invertebrate remains respectively, for vertebrate
remains abound in the beds from the horizon of Bed 15 (that is,
the main Bone-Bed or its equivalent) downwards; while inver-
tebrate remains predominate in that portion of the Westbury Beds.
which lies above Bed 15.

Beds containing an abundance of vertebrate remains occur at.
several horizons in the Westbury Beds; but one stratum, that.
which I have numbered 15 in my various sections, I regard as
a contemporaneous deposit. Ceratodus teeth are abundant in it
at Aust Cliff; they have also been recorded from the equivalent
stratum at Garden Cliff, near Gloucester, and at Blue Anchor Point.
in West Somerset. Indeed, the teeth of this fish might almost be-
looked upon as zonal fossils.

At Aust Cliff the Bone-Bed (15) rests directly upon the
Tea-green Marls, and contains rounded lumps of that subjacent
rock. But at Blue Anchor it is separated therefrom by 22 feet of
Westbury Beds, 14 feet or so of Sully Beds, and about 80 feet of
Grey Marls.

The deposits that belong to the Westbury Beds and occur below
Bed 15 in the Watchet district include a number of nodular lime-
stones with a most interesting series of invertebrate fossils—
among them being excellently- gered specimens of Pteromya
cr Sree Moore, and other rarities.

The sections near Watchet have long been known to be more:
than usually rich in fossils, the comparative scarcity of which,,
if not their absence elsewhere, was a. matter for investigation.
Now, however, it will be seen that there is a series of beds below
Bed 15, ‘infra-Bone-Bed deposits’ they may be called, in the
Watchet district, which is not equalled elsewhere in the country.

North of Aust, at Garden Cliff, infra-Bone-Bed deposits are agaim
in evidence; but their geographical distribution to the north, as
shown by sections along their outcrop, is not extensive, and was:
probably governed by earth-movements anterior in date to their
time of deposition.

As regards the Westbury Beds above Bed 15, the following
points should be noticed :—

(1) The Pleurophorus Bed is a useful horizon, is frequently of bone-bed!
nature, in West Somerset is crowded with gastropods, and is ae
the bed that, at Beer Crocombe, Moore called the ‘ Flinty Bed’ ;

(2) Between the maxima of Preria contorta and Chiamys valoniensis ore is'
generally a rather barren deposit of shale ;

(8) The horizon of the maximum of Chlamys valoniensis is generally marked
by one or more limestone-beds ;

(4) Somewhere about a foot below Bed 7 is the niveau of the ophiuroid
Ophiolepis damest ;
(5) The Cardium-cloacinum Bed is well characterized by Cardium cloacinum

Qu., and affords an excellent datum-level for correlating sections on
the Bristol-Channel littoral,

Vok67:)" WEST, MID, AND EAST SOMERSET. ®

Thus, while the Westbury Beds above Bed 15 can be correlated,
as regards their component deposits, very tolerably, the same
remark does not apply to those below that bed.

The black shales of the Westbury Beds in this country usually
give place somewhat suddenly to pale marls and equally pale
associated limestones. The difference in lithic structure between
the Westbury Beds and these succeeding ‘ Cotham Beds,’ as they
may be called, is nothing as compared with the difference in
faunas. These dissimilarities suggest interruption in sequential
deposition, and the probability of such interruption is seen when
the beds near the junction-line of the two subdivisions are studied.
In the railway-cuttings at Sparkford Hill and Charlton Mackrell
the great boulder-like masses of stone at the top of the Black Shales
point in the same direction as does the interesting discontinuity
of the pale greenish-grey deposit at the base of the Cotham Beds
at St. Audrie’s Slip, near Watchet. The causes producing these
phenomena effected the initiation of conditions suitable for the
formation of the pale deposits which—as already remarked—may
be called the ‘Cotham Beds,’ with their interesting assemblage
comprising Hstherie, ostracoda, and Lycopodites.*

Upper Rheetic.

Cotham Beds.—tThe succeeding division of the Rheetic Series,
the ‘ Upper Rhetic’ of my former papers, or the ‘Cotham Beds,’ *
differs (as already hinted) considerably from the one which
it overlies. The component deposits are very different, and so
too is the fauna. Pale marls and limestones largely compose it,
and at certain horizons ostracoda, plant-remains, and Hstherie are
abundant. The bed in which the EHstherie and plant-remains
mainly occur in Worcestershire and North-West Gloucestershire is
a well-marked limestone with arborescent markings, and, except
tor the Psewdomonotis Bed or its equivalent, is the only limestone
in the Cotham Beds. But, from the neighbourhood of Chipping
Sodbury southwards to that of Bristol, there are usually a number
of impure argillaceous limestone-bands in the Cotham Beds, and
_ phyllopods, as also remains of lycopods, occur at several horizons ;
while over the greater part of Somerset there are at least two
noticeable limestone-bands, in addition to the Cotham Marble or its
equivalent. Ostracods are most abundant immediately below the
Estheria Bed, but occur also in the marls above. ‘The Cotham
Marble is frequently rich in specimens of Pseudomonotis fallax ; and,
of course, in the Pseudomonotis Bed of Garden Cliff such specimens

1 Lycopodites and Estheri¢ have not been discovered, so far as I am aware,
south of the Mendip Hills. Hapsford Mills in Vallis Vale is the southern-
most place at which I have obtained them.

2 After Cotham, near Bristol, where the Cotham Marble is well-developed.

8 MR. L. RICHARDSON ON THE RHZTIC OF [Feb. 1911,

abound, literally covering the surfaces of the thin pieces of limestone
that can be there split off from the bed.

The main point to notice, however, so far as Somerset is con-
cerned, is that the Cotham Beds are persistent south of the Mendip
Hills, if not quite so thick as in North-West Gloucestershire, and
divide the Black Shales (Westbury Beds) from the White Lias
proper (Langport Beds).

Langport Beds.—The change from Cotham Beds to Langport
Beds is considerable, palzontologically more than lithically. In
other words, some pause in the normal sequence of deposit is again
suggested. The frequently Lrthophagus-bored and Dimyodon-
encrusted nodules of. Cotham Marble, as at Dundon Hill (p. 39);
the ‘false’ or conglomeratic Cotham Marble of Culverhole, Somer-
ton, Sedbury Cliff, Aust Cliff, etc.; the remarkable relationship of
the Cotham-Marble equivalent to the Langport Beds at Lilstock,
are all facts which point to a temporary interruption of sequential
deposition, connected doubtless with the causes that brought about
the conditions suitable for the formation of the richly-fossiliferous
Langport Beds or the well-known White Lias proper.

In Somerset, in the fine section in the railway-cutting at Charl-
ton Mackrell, where the Langport Beds were so magnificently
exposed, they were separable into five groups. The first and top
one embraced the ‘Sun’- and ‘ Block-Beds’; the second, the
‘Rubbly Beds’ and three massive limestones; the third, more
regularly-bedded limestones; the fourth, similar beds, but with a
massive top-bed, often coralliferous (Lhecosmilia ? michelind Terq.
& Piette); and the fifth, very massive limestones, locally called
‘the Sizes.2. The mammillated and often bored upper surfaces of
the Sizes, together with their irregular nether surfaces ; the irre-
gular, rubbly, and conchoidal fracturing of many of the other beds;
and the way in which the fossils are attached to the upper surfaces
of the limestones or are embedded in the marl, all bear witness to
the slow rate at which the Langport Beds were formed.

Dimyodon intus-striatus, which makes its first appearance in the
Pteria-contorta Shales and is usually absent from the Cotham Beds,
appears in great force. Moreover, specimens of Volsella minama
(Moore non Sow.), Ostrea liassica, Playiostoma valoniense, and in
places internal casts of Cardinia and Protocardia abound, but do
not appear to be of any use zonally.

Watchet Beds.—These beds have a very restricted geographical
extent: it is approximately coextensive with that over which the
Sully Beds were laid down. They are not very interesting, com-
prising marls with inconspicuous and impure limestone-layers, that
contain occasional specimens of Ostrea liassica Strickland and
Volsella minima (Moore non Sow.). They are distinct from the
Langport Beds, decreasing in thickness eastwards as those increase,
and also from the Lower Lias that overlies them.

Vol. 67. WEST, MID, AND EAST SOMERSET. 8)
3 >)

Lower Lias.

Above the Watchet Beds come the ‘ Paper-Shales’ of the Lower
Lias and the Ostrea Beds. The Paper-Shales are very distinct from
the underlying Watchet Beds, and it may be that in between is the
stratigraphical position of Moore’s ‘ Insect- and Crustacean Beds’:
beds which are well-developed at Camel Hill. It is pleasing to
find that this careful stratigrapher, Charles Moore, held that these
beds were often absent; but he did not sufficiently emphasize the
point. In many parts of Somerset, as at Curry Rivel and on the
Nempnet outliers north of the Mendip Hills, the top-bed of the
_ Langport Beds is pierced by annelid-like perforations. The imme-
diately superincumbent strata are generally the Ostrea Beds, and
the perforations furnish evidence of a non-sequence.

Thus it appears that the reason why the several subdivisions of
the Rhetic are so well marked off one from the other, both as regards
faunal and as regards lithic characters, is because generally they are
non-sequentially related. A study of the English Rhetic supports
Suess’s statement that, while the dominant movement was one of
subsidence and not local but extended, it was, nevertheless, not a
sudden event, ‘ but oscillatory and slow.’ *

The following table will show at a glance the classification of
the Rheetic Series followed in this paper ; its relationship to the old
arrangement; and also the thicknesses of the several stages of
deposit, as noted in the South-West of England—bet ween Gloucester
and the English Channel.

TABLE I.—CLASSIFICATION OF THE RHZTIC SERIES.

Approximate
thicknesses in
Lias. LoweER. Ostrea Beds, etc. England.
c {( I. Watchet Beds (‘Marly rea 0 to 7 £t. 7. ins.
| of the White Lias’) ......... ey
Urrzr 4 II. Langport Beds (White rey 0 Resort fopk.
s | proper )iic.-7e cok. ota eee
HETIC « III. Cotham Beds (‘ Upper ie Age to 19. tte
L Rhetic’) ..

IV. Wresthuny Beds (Black Shales) 1 to (?) 47 feet.
LowER | V. Sully Beds (Fossiliferous fo Eanarrone.
Garey Ms) ie 28 cs een dan

Grey and Tea-green Marls ......... about 11 to 115 feet.
T to)
Keuren } Urrse 1 Red Marls.
The sequence of maxima of notable fossils has been inserted in
Table II (p. 10).

1 «The Face of the Earth’ (Transl. H. B. C. Sollas) vol. ii (1906) p. 268.

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Vol. 67.| THE RHZTIC OF WEST, MID, AND EAST SOMERSET. 11

III. Locat Deratts.

(1) West Somerset.

In West Somerset Rhetic deposits occur in two tracts: the one
a small outlier capped with Lower Lias at Selworthy ; and the other
in the comparatively long stretch of country alongside the coast,
_ extending from Blue Anchor Point to the Parrett at Combwich.

(A) The Selworthy Outlier.

Rheetic beds are not now visible in this outlier; but, since the
ordinary Red Keuper Marls are to be seen in the bank of the
‘Porlock Road, and the Ostrea Beds are worked in the wood at the
turning out of the main road for Blackford, there is no reason to
think that they are otherwise than normally developed, although
very probably not so thickly as at Blue Anchor.

Etheridge has referred to some section in this outlier, which was
open when he visited this neighbourhood about 1870, as the
‘Lower Venniford’ section’; but he gives no details concerning it,
and I have not been able to locate it.

(B) The Watchet Area.

(i) Introduction.—The Watchet area is best known in
connexion with the discovery, by Prof. Boyd Dawkins, of the teeth
of the earliest-known mammal, Microlestes rheticus, at a distance
of 103 feet down in the marls that were then called the ‘Grey
Marls.’ °

The Bone-Bed at Blue Anchor was first discovered by one Robert
Anstice, who obtained a considerable number of vertebrate remains
therefrom,’ and attention was again drawn to it in 1860 by
Thomas Wright.*

Then came Prof. Boyd Dawkins’s paper in 1864°; which was
followed by one from Etheridge entitled ‘ Notes upon the Physical
Structure of the Watchett Area, & the Relation of the Secondary
Rocks to the Devonian Series of West Somerset.’° He discusses
the St.-Audrie’s-Slip and railway-cutting sections ‘south of
Watchett’ in some detail; and refers to that at ‘ Little Stoke’
(Lilstock), but there is no mention of that at Blue Anchor.

On Sheet 47 of the Vertical Sections, published by the Geological
Survey, is a record of the St.-Audrie’s-Slip section by Bristow &
Etheridge (1878).

In 1896 the Geologists’ Association visited the neighbourhood,
and a paper, of the nature of a résumé, was written for use on

? Proc. Cotteswold Nat. F. C. vol. vi (1871-77) p. 37.

> Q.J.G.S. vol. xx (1864) pp. 397-402.

° Trans. Geol. Soe. ser. 2, vol. i (1824) p. 301.

* Q. J. G.S. vol. xvi (1860) p. 384.

° Ibid. vol. xx, pp. 397-402.

° Proc. Cotteswold Nat. F. C. vol. vi (1871-77) pp. 35-48.

12 MR. L. RICHARDSON ON THH RHZTIC OF [Feb. 1911,

the excursion by the Rev. H. H. Winwood,’ who also revised the
subsequent ‘ report.’? |

In 1905, in a footnote to my remarks on the Sully Beds at
Lavernock, I mentioned that I had identified the Sully Beds on
the Watchet coast °; but it did not have the effect of directing the
attention of the authors of the Geological Survey Memoir on ‘ The
Geology of the Quantock Hills, & of Taunton & Bridgwater,’ issued
some three years later, to the beds. In this memoir Bristow &
Ktheridge’s section at St. Audrie’s Slip is summarized and repro-
duced with some slight additions and emendations, and the same
remark applies to Prof. Boyd Dawkins’s section ‘ about a quarter of
a mile east of Watchet Harbour.’ Except for a section ‘in a quarry
between Hill Farm and Beere Farm west of Combwich,’ which is
diagrammatically represented, there is no additional information
requiring particular notice here.*

It is indeed strange that the fine sections in the foreshore and
cliffs at Blue Anchor and Lilstock (Little Stoke, auctt.) should have
received practically no attention ; but probably the cause lies in
the comparative inaccessibility of the neighbourhood.

(11) Stratigraphical Details.

Coast from Blue Anchor to Watchet.—In this part of
the area the Rhetic deposits have been bent into a slight anticline,
and have been let down between two faults: one inshore, and the
other far out in the foreshore.

The photograph reproduced in Pl. I will give an idea of this
slight anticlinal arrangement of the beds. The Rheetic deposits,
high up in the cliff, were, of course, once continuous over the axis
of the anticline; but, while they have been removed therefrom,
they may be seen again in the foreshore dipping Channelwards—
the hard beds giving rise to prominent ledges (PI. II).

The junction of the Red with the Tea-green and Grey Marls is
seen in the interesting ‘ Warren Farm Section’ in Cleeve Bay, a
short distance eastwards along the coast from Blue Anchor Point.
Fig. 1 (p. 13) shows the position of this section, and Pl. [V makes
clear the arrangement of the beds. In this section, Beds 22a to
12 are to be seen—the actual junction of the Tea-green and Grey
Marls with the Red being displayed to the right of the observer,
when he stands facing the section depicted in PI. IV.

Returning to Blue Anchor Point (Pl. I), the two prominent
bands of marlstone near the base constitute Bed 20 of the record on
p-20. In Pl. III, fig. 2, is reproduced a photograph of the Keuper
Marls, with their bands and veins of gypsum, from this Bed 20 up
to Bed 11; while descriptive details will be found on pp. 19-20.

The uppermost beds of the Keuper, the Sully Beds, and the lower
portion of the Westbury Beds are very difficult of access at Blue
Anchor Point. Fortunately, however, several other sections are
available.

1 Proce. Geol. Assoc. vol. xiv (1896) pp. 378-88. 2 Ibid. pp. 483-36.
° Q. J. G. S. vol. 1xi (1905) p. 389. 4 Op. cit. Mem. Geol. Surv. pp. 65-71.

Vol. 67. WEST, MID, AND EAST SOMERSET. is
3 9

On turning the Point, the first gypsum-workings will be seen.!
A path leads from these workings to the top of the cliff; and, about
half-way up it, the Pteria-contorta Shales will be noticed in the bank
alongside the track. On the right is a steep, but (owing in places
to the talus) accessible, face of rock in which the uppermost portion
of the Sully Beds, and Beds 33 to 26 of the Westbury Beds, can be
made out. The hard, grey-blue, nodular limestone-masses, called
‘The Clough,’ are very conspicuous.

Fig. 1.— View of Cleeve Bay looking towards the North Hill, Minehead.

L. R. photogr.

[To show the position of the Warren-Farm section on the shore-line
where a line connecting the two arrows would strike it.]

Down on the foreshore, opposite these gypsum-workings, the con-
tinuations of the same beds, that is of Beds 33 to 26, along with
higher deposits, up to and inclusive of the Plewrophorus Bed,
Bed 13, can be readily identified. The basal deposit of the West-
bury Beds (Bed 33) contains small nodules, derived from the sub-
jacent Sully Beds, which weather out very conspicuously, as do
also the contained coprolites and fish-remains. In this section the
‘nodules’ occur in a regular course, and are parted from the Sully
Beds by an inch or two of black marl; but, in the next section
to be noticed, they are seen to be more intimately connected with
the basal bone-bed. ‘The Clough’ is interesting, because it is its
nodules that are principally sought for on the shore, placed in
baskets on the backs of donkeys, and taken to the lime-kilns for
burning, as they make the best lime.

* Proc. Geol. Assoc. vol. xiv (1896) p. 384.

14 MR. L. RICHARDSON ON THE RH#TIC OF [Feb. 1911,

The next section, also in the foreshore, is that depicted in Pl. II.
Here each individual layer can be readily investigated and searched
for fossils, which are abundant—especially in the Pleurophorus
Bed—and well-preserved. It was here that the details recorded
on p. 17, under the heading ‘ Foreshore Section near the First
Gypsum-workings,’ were obtained, and the numbers in Pl. II
correspond to those tabulated in that record.

It is unfortunate that it has not been possible to connect the last
section with that exposed at Blue Anchor Point, where the beds are
accessible again; but, as already remarked, the Blue-Anchor-Point
section is a very difficult one to examine, and the investigation of
the higher beds is not unattended by actual danger.

The main Bone-Bed (15) was not visible in the Point section
when I visited the locality ; but I procured some excellent specimens
loose on the cliff-slope, by working along in the direction of the
Point from the section by the path-side near the gypsum-workings.
Typically, the bed is a very hard, grey, compact siliceous sandstone,
crowded with fish-scales and teeth and occasional fragments of
bone. The surface of the main bed, where it rises along the fore-
shore forming that conspicuous reef (Pl. II), has a distinctly gritty
appearance—the grains weathering out very distinctly along with
the vertebrate remains. But the bed is subject to some variation
for, by the pieces picked up on the cliff-side, it is seen to comprise
several layers, the topmost of which consists, in its upper part, of
the same kind of siliceous material as that in the foreshore, but
dull greyish-blue, rarely vertebratiferous limestone in -its lower.
Occasionally the uppermost layer also is shelly, containing indeter-
minable examples of a species of Jsocyprina.

' The Bone-Bed of Blue Anchor is probably on the horizon of the
series of beds included under 15 at Lavernock Point. At Laver-
nock, strange to say, there is no distinctive Pleurophorus Bed.
Where it is to be presumed that it should come is a marked line in a
black-shale deposit, with thickly-laminated shales below and thinly-
laminated shales above. Then comes Bed 9—a limestone-band,
frequently nodular, which (there can be little doubt) is correlative
with a similarly-numbered bed at Lilstock and in the railway-
cutting at Charlton Mackrell. Shales, quite twice as thick as at
Lavernock, separate from Bed 56 the limestone which I consider
to be on the horizon of Bed 9.

The identification of Bed 5 6 at Blue Anchor Point is very im-
portant, as it affords a sure datum-level for correlative purposes,
connecting this section with that at Bishton, near Newport (Mon.),
and with that at St. Audrie’s Slip to the east of Watchet. As
regards lithic structure, it is difficult to separate hand-specimens
of the bed from these three localities, and the principal fossils
occur in about the same proportion, as regards numbers, at the
several localities named.

At Lavernock Point, where I measured the section which I have
published,’ there is a non-sequence between the ‘ White Lias ’ and

1 Q.J.G.S. vol. 1xi (1905) table facing p. 592.

LOWER LIAS.

—_—-

UPPER RHATIC.
ee eens

-

Vol. 67.] WESL, MID, AND EAST SOMERSET. 15

the ‘ Cotham Beds’—the lowest bed of the ‘ White Lias’ there rests
non-sequentially upon the lower portion of the bottom deposits of
the Cotham Beds, which have been partly eroded and fissured,
and the cracks filled up with gritty material, before the lowest bed
of the ‘ White Lias’ there present was laid down. Here at Blue
Anchor, however, the Cotham Beds are complete. The ‘ White
Lias’ or Langport Beds of Blue-Anchor and Lavernock Points cor-
respond remarkably well, as the numbers in square brackets (below),
which refer to Lavernock, are intended to indicate.

The shales, which I lettered A at Lavernock and grouped pro-
visionally with the ‘ White Lias,’ are represented by an increased
thickness of similar deposit at Blue Anchor Point, and I have
suggested that they shall bear the name of ‘ Watchet Beds” They -
are succeeded at Blue Anchor, as at Lavernock Point, by those very
distinctive hard brown shales for which the name of ‘ Paper-Shales’
is So appropriate—occasionally hardened at the base to simulate a
limestone-band, Then comes that massive limestone which doubt-
less corresponds to the ‘ Bottom-Lias’ bed at Dunball (p. 33).

Section at Brut AncHor Point, NEAR WATCHET.
Thickness in feet inches.

i Rei, Mae? ;
E Pee mike Ostrea liassica Strickland.
Shales, hard, pale-grey and brown, becom-
< ing compact and passing down into a 70 9
fissile ..... ‘
Limestone, which is not always con- 0 = Paper-Shales.
SED SEUECOLTICIN b RUINS rs MIR aa sen Sen ce Oe

Shales, well-laminated, brownish-yellow,
with a few thin layers of gritty lime- ri 9
stone, one especially noticeable at 11
inches above Bed 2; about ...............
Marl, yellowish, sandy in appearance ... 0 A,
Shales, hard, brown, laminated, with thin 1 9
ilnyverstot tibrousicaleibe vec 1. oecc <-->
Shales, bluish-grey, not very well lami- 1 Ostrea liassica common at
TIGIHDS. 25 pete ane | A Reece eee ee AN the top.

—
=

eee ote,

CR

WatTcuHET BEDS.

Limestone, bluish-grey, weathering pale-
5 ! brown, but often not very conspicuous : ¢ 0 2 Ostrea liassica.
Dabo AMINC HES Ae sis. oan ee Fragment of Ostrea, Di-
6. Marl, bluish-grey, laminated: 3 to 4 0 3 myodon intus-striatus
TNC]: RIN Aine aa aR oa ec Cs (Emmerich), Chlamys

7. Limestone, ied Lae own and bluish- ho 1 (sp. indet.).
SIOVACEMLTEG 0nd ou ee eee ane ee
Se amply a] 00. «lo gee Ie a ee 0)

fi i
(Limestone, hard, greyish- eae va

TBs shelly, conchoidal fracture. At Ost liassi
P i the base, which is very uneven, 70 Vi, ; ee ee (common),
4 are lumps of a more compact and umyouon mtus- striatus.
ZB paler limestone ..... eee
= a Marl, brownish-grey SL paaee Ont
FA Limestone, often absent, Dimyodon intus-striatus,
= 5 [4] brown and sronhvgrey, Ora’ : Protocardia rhetica (Me-
2 earthy : Oto Linch ........: rian).
o a al ; Marl, pale-brown with a ou é
a toal A thin limestone at the base. }
= Limestone, brown, ae 0) 55
10 tet Marl, brownish . 0 15
0 1 Shell-débris.

Limestone; hard, “pluish-
11 [10] ; grey, conchoidal fracture }

2 3

UPPER RHATIC (continued).

O
=
i=
FA
eo
S
ow
=
S
eo)
|

16

[Bruz Ancnor Pornt.]
Shales, dark-brown
1 se ey, -Marble peer ae ary
to 3 inches..........

2. Shales, ¢ ereenish- -orey, ‘calcareous . 1
3 Limestone, pale - eats blue - 3 0
centred ..... eh
(Shales, ereenish- -orey, “with thin

layers of a pale-green limestone
full of shell-débris. The deposit
from the base up to 8 inches
therefrom (and of a brown tint) is Lo
closely packed with thin limestone- {
layers, so as to constitute in places
a compact stratum, which is sepa-
rated from the underlying bed by
L more shaly matter
( Limestone, pale greenish-grey, on)
| the whole a conspicuous and mas- |
(2)< sive bed, including at the base a F1
| bluish-grey limestone 3. inches |
L thick: 14 to 16 inches ............... J
Marl, brown, clayey: 2 to3 inches. 0

CotHam BeEps.

sae
~~
=
—

L 4g

(3)

Shales, black, with thin brown : 0
seams .....

(1)3 Conspicuous brown shelly s seam and 3 0

1

‘beef’ ;
Ly Shales, ‘black, very osteo
at the base: 10 to 16 inches
Limestone, blackish, pyritic, with )

a 13-inch layer of ‘beef’ on the |

top. Much black shale is mixed L

with the limestone. Very pyritic |
; in places, and when decomposed is
L of a rich reddish-brown
L(3) ; Shales, black, laminated : 18 inches ; 1

to2 feet ....

Cardium-cloacinum Bed. Lime-

1 stones, thin, very dark-grey, with

a shale - partings, associated with | 0

H nodules of pale-grey hard iNesae (P
L stone—the Cardium-cloacinum |
IBEd) PLOPeL., shee ces ceees eee eee |

ia Shales, black, with thin limestone-
iC (1) layers intercalated among them
| near the base and containing many
fossils..
(2) oes blackish, mixed iy
| shale, and extremely fossiliferous
| 6.5 (3) Shales, black ........ Beers 30)
p Shales, earthy, black, "calcareous,
a 4)+ bound together by “beef” so as $0
fe to resemble a hard bed...............
© (5) Shales, black 0
a | | (6 Ve Beef,’ often resting upon a Lane
= Tnectone 4). oc eee eae
a L(7) Shales, black 0
cs Limestone, grey- -black, somewhat
= i hal »
sh A eas
| (1) Shales, black, thinly laminated. ach 3
Limestone, impure, shaly, full of
8, (2) § bo
Shells ......
3

(3) Shales, black, thinly laminated...

MR. L. RICHARDSON ON THE RHATIC OF

[Feb. 1911,

Thickness in feet inches.

4,

2
O Ostracods at the top.
4

Pteria contorta (Portlock),
Chlamys valoniensis (De-
france), Dimyodon intus-
striatus (Emmerich).

2 myodon intus-striatus.

In the top portion of this |
deposit Chlamys valoni-
ensis and Pteria contorta
are common ; Placunopsis
L alpina (Winkler).

A ardium cloacinum Quen-
|
L

6

bee” valoniensis, Di-
|

stedt, Protocardia rhe-
tica (Merian), Pteria con-
torta, Placunopsis alpina,
Ostrea sp.

3 (Pteria contorta, Chlamys
valoniensis, Placunopsis
alpina (large), Pleuro-
< phorus elongatus Moore,
| Dimyodon intus-striatus,
L

2

Protocardia rhetica, Vol-
25 | sella minuta (Goldfuss).
Chlamys valoniensis and
! indeterminable shell-frag-
ments.
4 Pteria contorta, common.

~

Chlamys valoniensis, Pla-
cunopsis alpina, Nucu-
< lana cf. titei (Moore),
| Acteéonina fusiformis
le

fee elongatus,

(Moore), A. oviformis
(Moore), A.ovalis|(Moore),

OW uty Duh tL (continued).

.
SS | ee peepee anemone poser cal

Vol. 67.]

[Brvur Ancuor Pornv.]

Limestone, very hard, ano 0
slightly, pyrities ©. 45::¥ac..2s. <e.ice
Shales, black, laminated

FoRESHORE SECTION NEAR THE (6
First Grpsum-WoRKINGS.

Shales binele eed 22% sche. Auta
Pleurophorus Bed. The Pleuro-)
phorus Bed proper is a dark-grey,
earthy fissile limestone crowded
with Pleurophorus,and constitutes
the lower portion of the bed. It

little shaly matter or ‘ beef,’ while
the upper portion of the bed is
often replaced by ‘beef’ or sur-
rounds lenticular masses of hard
dark limestone
Shales, black
The Bone-Bed. Upper layer a)
hard massive grit, with many fish-
remains. It is separated from the
lower bed by a distinct parting. >0
This lower bed is a fine-grained,
more regular crystalline rock, con-
spicuously ripple-marked............ z

y oo
GN ee

Wesrpury Bxps (continued).

“0 to
J

19.

3
;

1 inch) of seh limestone : 0 to |
inches

16. Shales, black, laminated
(verde hard, erey, micaceous |
ron} and ey somewhat siliceous : 0 to |
5 inches
17. J gin often containing athin band ,
2 inches.. a
ae ‘fissile, arenaceous :
Zeb TNC) EIS A ee ee ean ee a el
(eine Bla lege a a tins Seek Paes: 1
Limestone, grey, in lenticular
masses; baryto-celestine: O to ato
Shales, black, with a number of
| more or less prominent sntstone-
layers-at the ‘base’. ...c20..2c45406055
Limestone, rather prominent, very
hard, irregular, often of septari-
(1)< form nature where the Pteromya-
Limestone is wanting: O to 10
NEVE) EIS RA ee OO Ren Re Pla
Cyeisuales| WV inen 22... Jesccor- cae ee
Limestone (Pteromya Bed). Hard
(3) 4. grey and dark-grey limestone: 1
HOt MENES 22.5 ease t eee meee
22. Shales, black: 10-to 14 inches ...... 1
Limestone-nodules,
| hard,
apart horizontally : 0 to 2
iles. DRG jl ka: eee fi
| Limestone, hard, grey-blue, ent
0)
ss

at considerable distances

inches .

what intermittent, nodular in
places : 0 to 4 inches
(1) Shales, black, about

Limestone or greenish-grey impure
| 26.4 (2) sandstone, mixed with some black 0
: shale : sometimes absent, but usu-
ally about
(3) Shales, black

Fo SRE eee ee eed ek 3

@ J, G.S. No. 265.

WEST, MID, AND EAST SOMERSET.

is separated from the upper by a +0

is
J

--greyish-blue,)
0)

17

Thickness in feet inches.

6 Fish-scales.

5 [Suggested approximate
thickness. ]

Gervillia precursor Quen-
stedt, Pleurophorus elon-
gatus (very common), Iso-
cyprina ewaldi (Borne-
mann), Chemnitzia (two
species), Ch. granum Ditt-
mar, small _ coprolites,
fragment of an ichthyo-
dorulite of Nemacanthus.

1 No fossils seen.
( Isocyprina ewaldi, peculiar

| tracks as indentations
6 J Gyrolepis alberti . Ag.,
| Acrodus minimus Ag.,

Ceratodus latissimus Ag.,
| Hybodus minor Ag.

(3) Isocyprina ewaldi.
6

ie.2)

Moore, very common,

(3) } Pteromya crowcombeia
Isocyprina ewaldi.

Protocardia sp. indet.

prina ewaldi, Pleuro-
phorus elongatus, Natica
oppeli Moore, Chemnitzia

0
1
2 ( Pteria contorta, Isocy-
2
O L sp. nov., and Ch. granum.

the hardened infillings of

jhe hy protuberances like
tubular bodies.

LOWER RHATIC (continued).

18

eee ———————— — —

WestBury Bens (continued).

en
——E

[Buvue Ancuor Porn. |
‘The Clough.’
grey -
central cavities attached to the
nether side of a thin black shelly
limestone, which in its turn is
separated by shaly matter from a
‘bone-bed ’ limestone

il.
2.
mn
al 3.
fara)
s Ay,
5
D 5.
2) 6.
The
8.
ese
10.
1.
of 2.
ie2)
Ay
wi 3.

f

1

Anan

MR. L. RICHARDSON ON THE RH ATIC OF

Limestone, hard, )
blue, nodular, with calcite in

70

Shales, black, laminated ............. 1

(1) { Sandstone, soft, light- -grey, > partly ¥ ho
pyritic: a ‘bone-bed’ ...

(2) Shales, black ..... soe wl

(3) Sandstone, thin layer of earthy — 0)
Shales, blackish-green, marly, with
pale ereenish- -grey nodules (here

very conspicuous) near the base, -1
and some thin gritty limestone-
layers near the top ....:.............

(1) Sandstone, in irregular masses ...... 6)

(2) Shale, dark-green “and black, marly. 0

(3) { Sandstone, whitish, im very irregu- ; 0
lar raasses, spangles of white mica

(ae Shales, black, anenly ieee eee 0

( Limestone, very pale-grey, rather 0

d. crystalline ey TO ck aaa

(3) Shales, black oeal

(1) Shelly bed, limestone in places... 0

(2) Shale, black .. eo)
Basal Bone- Bed, resting upon

(3) } the Sully marlstone and ey 0
derived lumps thereof ...............

at the base.
white, fibrous,

[Feb. 1911,

Thickness in feet inches.

( Acrodus minimus, Gyro-
| lepis alberti, Hybodus

4 < minor, saurian rib, Nucu-
| lana titet (Moore), i in the
\. uppermost layer.

Comminuted fish-remains.

(st)

prina sp., Pleurophorus
elongatus.
(eee minimus, Gyro-
| Jepis alberti, Saurich-
thys acuminatus Ag.,

\ prin contorta, Isocy-
a5
2

Hybodus minor, Sargo-
don tomicus Plieninger,
Lepidotus (?) teeth, Pteria
contorta.

BuvueE Ancuor Pornt (pars).
Two massive beds of marlstone, greyish-

ereen,but weathering yellow and parted
by a thin layer of darker and less com-
pact marl: estimated at . Ld
Marl, laminated, yellowish- brown : esti-
0)
mated at
Marls, greenish-grey, “with A,
zones ...
Marls, black, “shaly, - more Bae
ANNOWE) coaabhe
Marlstone, weathering yellowish Bae ai 0
Marl, dark, shaly ; set)
M arlstone, erey, weathering yellow. ate 1
if Marl, soft, dark, shaly, with a 9-inch 1
band of marlstone about the centre ...
Marlstone, es: ere n hrod
Marl, soft... went ae (0)
Hard grey marl, with a dark zone at 1
the Waseic.cens- sear ne Meco eee
Marls, soft, black predominating in the ‘ 9
lower half and yellow in the upper ...
A series of layers of gypsum inter-
stratified in very dark greenish-grey
marls, with a particularly massive layer 7

The gypsum is pink and
and occurs mainiy in

horizontalclayersiee-e-ees eeeeeeereeeee

6

5

0

9

8

3

4

8

5 Tee (seales and
1 small coprolites).

1301

6
10

0)

Vol. 67. WEST, MID, AND EAST SOMERSET, 19
6}

[Brvur AncuHor Point (pars). | Thickness in feet inches.
| Pale, greenish-grey marl, less compact
4 ! but containing more ramifying beds of} 4, 0
¢ypsum than the bed below ............
Pale, greenish-grey, more compact marl
5.4 than 4, but with only occasional veins > 2 3
Ol RY PSM seas ee sess oo MiB coos avd rane
Series of grey, gypsifer ous marlstones,
a grey and green marls and marlstones: its
SiOUO tee bn mmne trey cs... «icsoumaramniee
Dark greenish-grey marl ....... iL
” Conspicuous layer of white. fibrous : 0
; gypsum ..... ge es Mare os ata tea eet
Mar! similar to aye ah os Nan a 4,
| Greenish-grey and slightly yellow marl- ; ie
2
;

I-OwbW @® oOo

8. stones (three beds), separated by black
shaly matter .........

Black shaly marls, not ‘very “compact, ;
6

ns

9.5 alternating with ‘ereenish- -grey marls
and traversed by veins of gypsum......
Three or four beds of greyish-green
marlstone, with black marl separating
| 10.< them, and traversed like the beds -4
fi above and below «by thin veins of
CH TISULTDY: geet See aa a
( Marlstones, grey, separated from ak
bed below by marl, green in the lower
portion, black in the upper (7 inches),
passing up into less massive grey marl-
stones mixed with much more black +9 0
marl containing pink gypsum, and
lastly—at the top—into a black shaly
deposit, in which marlstones are sub-
ordinate and there is more gypsum ... }
Two massive beds of oreenish-grey
marlstone and much pink gypsum.
These are the two bands so conspicuous
IMP OM VAMEMOL WOMMth 4... 2647 oases tics -

|

:

jo nodular marlstones, with =
A

!

|

ils

’

12.

=

GREY anp THAa-GREEN Marts (continued),

co a ee ee eee ee ee oe Ce :
pt
OX

13.4 shaly marl, much pink gypsum, and
veins of white YIP SUM e se ge ees d ee

Marl, green, with some pink gypsum
and a very regular layer of white
fibrous gypsum. Below this are veins
of pink gypsum obliquely arranged

Seven layers of somewhat nodular er een-)
ish-grey marlstone interbanded with |

black shaly marl, which has running in

14.

it layers of gypsum mainly in a hori-
zontal position, while the pink layers |
are in the main obliquely arranged. |
The topmost marlstone is more regular,
| conspicuous, and of a lighter colour ... J
{ Marlstone, hard, dirty, yellowish-grey, Teo
eypsiferous at the 10) OA cree, SPAN

Dark green marl, with a thin but con-

| spicuous layer of white gypsum near ¢-l 3
the'top «......

Marl, blackish, with a “ereen ‘tinge and )
|

——_

a faint red zone near the base. It is
traversed by one very conspicuous layer
of white fibrous gypsum and also by
oblique and ramifying veins of pink. Lg 6
At the top is a noticeable zone of pink

gypsum in green marl, overlain by
blackish marl that fills up the irregu-

larities in the hard Chcbiae of expen

below "ssc

KEUPER (continued).

c2

[Buur Ancuor Pornt (pars). |

KEUPER (continued).

20 MR. L. RICHARDSON ON THE RH TIC OF (Feb. rorr,

Thickness in feet inches.

| 19. Marl, blackish .. See tal 2
Marlstone, hard, greenish-grey.. Poet dk 0
20 Marl, greenish .. Bie 8 fe RR ae LO) A
*) Pale pink oypsum ube, ee 3
Marlstone, hard, yellowish-g oreen | a Sa 1 7)
PALE Greyish-green and dark marl ......... *. 8 6
IMiir VOTE DISD: coc Wee nae ae ere i 0
| Bein ere HAE ee Peete TG) 6
Marl, greenish 1 3
93 Dees erey marl, with a black om 1 6
at ‘the bases; dice. stecaseueeeer cence sci
24. Greenish-grey marl with a red zone...... 2 0
25. Marlstone.. PR cave ctiny GO 5
26. Greenish marl ‘and marlstone ............ 1 0
o7 j Greenish and dark marls, with two red 3 0
zones at the base . Ben
28. Massive greenish-yellow marlstone ...... 2 3
99. Marlstone, greenish-grey .................. 0) 6
Rep Pe red and variegated, faulted
Marts. ( against the Lower Lias. Motall.. 5... 11 (oO

Proceeding along the shore, and passing the Warren-Farm section
and the point where the track from the lime-kilns descends to the
shore—at about the place in the cliff which is above the arrow
on the left-hand side of the scene depicted in fig. 1 (p. 18), the
observer will find an interesting exposure.

SECTION IN THE CLIFF NEAR THE Lime-Kitns, west oF WATCHET.

Thickness in feet inches.
(1) [Shales: removed by denudation. ]
Limestone, cream-coloured and
A, < @} grey, with darker streaks and
nodular in places: seen.. ae

(8) Shales, marly, brown, ee

=)

9 Sun-cracks.

CoTHamM
BEpDs
(base)

down into

2 4, Very shelly.
@ Bue Shales, black, brown, and grey ...

( Cardium cloacinum |

Bee Qu., Pleurophorus

bo 5B rarer at Bed. Lime- elongatus Moore, |

peu stone intermittent ........0....0...... 0 84 ITsocyprina SPp., |

S A Myophoria emme- '

4 6.) Shales; black: seen. ..3 eos reer 0 0| richit Winkler, fish- |
le \. scales, etc.

Bed 4 (2) is interesting, having sun-cracks in its component.

layers, and reminds one of the Lycopodites Beds at New Clifton,
Bristol.

On this west side of Watchet there are no other sections that.

require attention.

Coast between Watchet and Combwich.—Sections in the | |

foreshore immediately to the east of Watchet have been described
by Prof. Boyd Dawkins, and those in the railway-cuttings at |
Doniford by J. H. Blake; but, so faulted are the beds, that their

investigation is more interesting from the tectonic than from the
stratigraphical point of view.

|

1 The details of the beds Boe 21 HOT OR ES were sietaL nad at the Warren- |

Farm section.

UPPER RH TIC.

Vol. 67.] WEST, MID, AND EAST SOMERSET. 21

St. Audrie’s Slip section.—The first section to notice east
of Watchet is the fine one at St. Audrie’s Slip. Its earliest describer
was Robert Etheridge, who, in a paper read in 1871 (Proc. Cottesw.
Nat. F. C. vol. vi, p. 40), spoke of it as the

‘most complete section of the Rhetic Series in Somersetshire, if not in the
West of England (except Penarth) .

The Rev. H. H. Winwood, ee, in 1896, thought that this
probably was so (Proc. Geol. Assoc. vol. xiv, p. 381); but at the
present time (1905) the lower part of the Westbury Beds is obscured,
and was so apparently in 1871: for Etheridge remarks that

‘the measured section in full detail was constructed some years since, at

a time when the Black Shales were in better order than at present, the sea
having made extensive ravages and changes in its aspect.’

Etheridge made his measurements in company with Bristow, and

the joint section was published officially by the Geological Survey
in 1873 (Vert. Sects. Sheet 47, No. 6).
In the recently published (1908) Geological Survey Memoir on

the ‘Geology of the Quantock Hills, &ce.’ (p. 68), the official section
ig re-stated, but in an abbreviated form.

Section at St. AuUDRIE’s SLIP, NEAR WATCHET,

Thickness in feet inches.

eee ee ae ee ( Ostrea liassica Strickland, Vol-
2 >) ‘
ee brownish-grey, with blue- ¢ 0 45 sh pone (Come: ee
<— SUEY ECWUES™ 2108. 5.62 en on oR © + tae Caer ae
S ? Clay, brown and black, ot 0 pe ee ee
a , limestone: 1 to 3 inches. ir
=) Limestone, very pale grey-
= brown, traversed by ex- 31
fo) a tremely thin ramifying 2
com ealcite-veims .............. we :
| {Shales bluish-grey, passing? yg Paper Shales
1 10 seen.
Shales, greyish, thinly la- )
minated. Some of the |
ae 1 J ye ses pe conn: an L 4 9 ee aaa lacetti (Moore),
ie 6‘ : cen bss
a | | the base (for an extent ex- Isocyprine (2) sp.
ar) | ceeding 5 inches) ‘these
a J \ shales are more earthy ..
a Limestone, earthy, bluish- ; .
5) 2. grey, somewhat nodular: > 0 5 Ce specimens of Os-
Zs PRISER 2a alee 2a nacete a ae ao
L Shales, rather earthy, blu- Sens
= ° ish-grey : 2 to 4 inches .., , ‘ ne pasate.
4, 10
Limestone, yellowish exte- )
rior, cream-coloured with Volsella of the V.-minima-
ms (f i bluish-grey patches inside, > 0 5 group (Moore zon Sow.) ;
A conchoidal fracture. Sur- Ostrea(?) on the upper surface.
ra face very irregular ......... DI
2. Shale, brownish, clayey ... O 0%

LANGPORT

UPPER RHATIC (continued).

22 MR. L. RICHARDSON ON THE RHZTIC OF [ Feb. grr,

(Sr. AuDRIE’s Srip. | Thickness in feet inches.

(Limestone, yellowish exte- ) (The upper bed has on its sur-
rior, grey interior. The face Plagiostoma valoniense
top is fairly even ; but the (Defrance), Dimyodon intus-

3 4 lower portion isrubbly and {| striatus (Emmerich). In the
|

shelly, containing nodular 9 rubbly portion Plagiostoma

nie

masses with pitted surfaces, | valoniense, Protocardia, an

and has a most uneven | echinoid-radiole, and ostracoda

iGhase-linte? 4... £3) |. —the last, common.

Shale, bluish- -orey, ; ‘indu-
rated and calcareous, espe-
cially at the base..

Limestone, grey, earthy,
with a slight bluish tinge.

Shale, bluish-grey, earthy .

6. ‘es hard, blue- -grey,

Ove it

0)
0 3

very slightly pyritic. Of-

bo
t|H

+f Shells rare, but a few specimens

ten divides, and in places of Volsella were noticed.

NS

dies out. 1 to 4 inches..

Limestone, hard, grey, 2

Langport Beps (continued).

choidal fracture, slightly

pyritic in places. Calcite

crystals. Oto 3 inches .
(1) Shale, bluish- = OVO... 6 aaa
Limestone, similar to
Where 7 is dev eloped 8 j
is not, and vice versd. Oto
3 inches oh
fe Shale- parting —

“T

a0 Ones

Limestone, bluish- -orey with

darker parallel streaks and { Cotham Marble” of Bristow

0

0 4, <
conchoidal fracture ...... ee nisin.
Shale-parting Pee rere A)
Limestone, average .........

{ [Position of Cotham
|
|

jo)

a

Marble, but not noticed A 2
by me at this locality. ]
Shales, greenish-grey, lam-
inated, calcareous, with a
few thin, greenish-grey, \ 0 pee and a few fish-scales
at the very top.

micaceous (white) sand. |
stone-layers in the lower ;

Cia ie cass este a eee J
Limestone. massive bed,
pale greenish-grey, bluish- 1 4

Ripple-marked.

grey inside, fissile, passing
down into
Shales, greenish-grey, ay 1
thin sandstone-layers ......
Limestone, similar to3 ... 0
Shales, pale Beare 0

AN.

CoTHAM *BEDs.

| with thin sandstone-layers
A, “ / ,§ Blnestone hard, a 0
grey, usually present here

me © &

; Protocardia (?)and fish-remains.
in the layer at the base.

(3) Sandstone, several hard |
| lay aes a greenish on, | The lowest hard band contains
ea 1 ae esa eRe ale SV elO many shell-fragments, includ-
) >, | : ws zs
L L subordinate vandunemtonl ing Cardium cloacinum Qu.
shale (Gee p25) ee

LOWER RH ATIC.

als 67:

(Sr. AuDRIE’s Surp.]

Westbury BEps.

Shales, black; with layers |
( (1) 3 of ‘beef? in places, and im- + 3 6 <

L

13.

WEST, MID, AND EAST SOMERSET. 23

pure limestone-beds_......

Limestone, dark grey,shaly,

(2) with 1- to 2-inch layer of
‘beef’ on the top or be-

low: maximum ............

(3) { Shales,

inches

( Cardium-cloacinum Bed ; )

| blackish earthy limestone
with a 13-inch layer of
‘beef’? on the top, and > 0

| in places very hard ss

On
i]

greyish limestone-nodules
\. below

Shales, black; crowded with

(1) § fossils bo
(‘ Beefy resting upon dark )

shaly limestone, in which

fossils are not numerous.

(2) < Joined on to this is a still > 0
| more shaly limestone, bee

a half-inch layer of ‘ beef
| at the base
(3) Shales, black ...... ere 0
Limestone, grey-black, mas-
sive, shaly in upper portion. 0
Thin layer of ‘beef’ at
the base, 4 to 10 inches ...
(Shales, black, laminated, )
with layers of ‘ beef’ at 4,
29, and 44 inches from
the base. Many gypseous
aggregations in the shale
~ between theJamine. The > 6
lowest 4 inches non-lam- |

inated. Hard, greyish-
black, shelly limestone at
the base (1 inch there-
| from)
| shelss hard, grey, with

shells inside but too fry 0
encased for extraction......
Shales, hard, thinly lamin-
Med paleouds A -cdon ess
\ Beef, resting upon a newt

2

grey earthy limestone with $ 0
shell-débris ........

Silas sist ve tej cane tates
( Limestone, very hard, crys- )
talline, pinkish, slightly
pyritic, in two beds. The
upper bed is 2 inches thick,
Pleurophorus Bed; the |
lower is 5 inches ‘thick,
with a layer of ‘beef’ and
shale intervening............ }

3

ee

Thickness in feet inches.

(In the uppermost 3 or 4 inches
Pteria contorta is abun-
dant; but below the shales are
more laminated, and contain
few fossils except along certain
\ lines.

( Along certain lines the following
fossils are numerous: Pteria
contorta( Portlock), Isocyprina

11 ewaldi (Born.), Chlamys val-
oniensis (Defrance), large
Placunopsis alpina (Winkler),

Nueulana cf. titet (Moore).

( Pteria contorta, Dimyodon in-

| tus-striatus, Chlamys valoni-
ensis, in the earthy limestone.
In the nodules, Protocardia
rhetica (Merian), Pteria con-
torta, Chlamys valoniensis,
Nuculana cf. titei, Acteonina
Fusiformis (Moore), A. ovalis
(Moore), Natica oppeli Moore,

| Placunopsis alpina, Cardium

L eloacinum, Serpula (?).

Chlamys valoniensis, Pteria

3 } contorta, Dimyodon intus-

striatus, Placunopsis alpina.

bo
h|H

1
Oz ( Chlamys valoniensis, Pleuro-
phorus elongatus Moore, Pteria
7 contorta, Placunopsis alpina,
Volsella sp., and a few fish-
scales.

the third ‘ beef’-layer from the

J he thint * immediately above
2
base, and again at the top.

(On the top Pteria contorta,
Myophoria emmerichiW inkler,
8 rare; Etheridge & Bristow
1 record, in addition, Anatina
suessi Oppel, and Plagiostoma

6 | valoniense.

2
Gervillia precursor Qu.,
6 } Protocardia rhetica, Pteria
contorta.
(Isocyprina ewaldi, Pleuro-
; phorus elongatus (very com-
8 mon), Chemnitzia (?) henrici
Martin (very common), Nueu-
lana cf. titet.

LOWER RHATIC (continued).

24

[St. AuDRIE’s Surp. |}

MR. L, RICHARDSON ON THE RH ATIC OF

[Feb. 1911,

Thickness in feet inches.

14, ia black, laminated s 1 6
; 15.402 inches, eee
(The Bone-Bed. Five lay- Acrodus minimus Ag., Gyro-
| ers of a dull grey siliceous lepis alberti Ag., fragments
15. < rock with rolled pieces of > 0 5 <~ of bone and coprolites, shell-
| limestone, and at the ca L débris (Isocyprina?), and small
| a layer free from pebbles .

16.

layers, thin,
a 0
with black shale 2:2...

Shales, black . Rae ee aL

Shales, black
Sandstone

greenish - yellow,

Limestone, ard grey. Se-
lenite and bar yto-celes-
tine, and fibrous calcite
(¢ beef ’) in joints ..

to the marls, according to (4

quartz-pebbles.

Shelly at the base, where it
contains Isocyprina ewaldi,
2 Volsella minima (Moore non
Sow.), and Pleuwrophorus elon-

gatus. Protocardia rhetica
. (teste Etheridge).

9|

WestTBuRY BeEDs (continued).

Etheridge, is 63 feet ‘Tess
i foot.9 1nehes'.. eee
Limestone-nodules, hard,
blackish: 0 to 2 inches ...
Shales, black and
speckled
Black earthy shale, with
quate of pale-grey marl. ; 0) 3
Basal Bone-Bed.........

bo 1
green- 4 6

Cee eee rer tee ere terres

he black. From Bed 17

33 0

( Hard, pale-grey,

( ? marlstone Fish-scales.

Greenish-grey marl ......... 0 4,
Marl, hardypale” <7.) ®) 6
Marl, greenish grey ......... 0 10
Marl, Hard Pale wae ee 0 2

( Shale, pale-gr ey, marly, with
thin lines of hard marl in¢ 1 0
the middle” 22202 4 se
Marl, hard, pale-grey, with 1
lines of softer mar] .........

i ; Marl, dark grey, tough, with ;

Suxty Beps.!

conchoidal fracture and

7 eee and Gervillia
thin hard sandy lines ......

precursor.

5 O+?°

Beds a, 6, & c¢ constitute the ‘Ostrea-Bed’ of Bristow & Ethe-
ridge, and correspond to the ‘ Bottom Lias’ of Dunball.

The authors of the official record, of the notes in the Geological
Survey Memoir, and myself, all differ with regard to the point where
the line between the Rhetic and the Lias should be drawn; but
I think that the horizon at which I have placed it is in harmony
with the allocation that I have made at other localities.

The component layers of the Langport Beds agree very closely with
their equivalents at Blue Anchor Point and Lavernock, and do not —
require anything to be said about them—beyond drawing attention
to the fact that the lower layer of the compound bed identified with
the Sun-Bed is very rubbly at the base, and contains well-rolled

7 The details of the Sully Beds are derived from Bristow & Etheridge’s
account,

Vol. 67.| WEST, MID, AND HAST SOMERSET. 25

pieces of close-grained compact limestone, thereby indicating a slight
non-sequence. Bristow & Etheridge noticed this rubbly condition
of the bottom part of the Sun- Bed in their record.

I have indicated the place where I should expect to find the
Cotham Marble if a longer search had been possible. ‘The horizon
pointed out is somewhat lower than that occupied by the stratum
suggested by the Geological Survey officers as its probable equiva-
lent. As showing that “the suggestion, that a continuous stratum
such as they indicate is the equivalent of the Cotham Marble, is
improbable, it may be remarked that in Mid and West Somerset
the equivalent of the Cotham Marble is generally an intermittent
layer of nodules—not a continuous limestone-bed.

A very interesting feature about this St. Audrie’s-Slip section is
the peculiar arrangement of the deposits in the neighbourhood of
the junction of the Langport and Cotham Beds. At the base of the
former division is Bed 4 (3) 6: it is remarkably persistent, and there-
fore constitutes a good datum-level. But, while in one place it rests
directly upon the Pteria-contorta Shales, in another it is separated
therefrom by a greenish marl 22 inches thick | Bed 4 (3) c].

At this horizon, at Charlton-Mackrell (p. 42) and Sparkford-
Hill (p. 48) railway- -cuttings, occur those remarkable boulder-lke
masses of limestone which “themselves are indicative of disturbed
conditions of sedimentation. Here at St. Audrie’s Slip is evidence
pointing in the same direction, and these facts considered together
afford some explanation of the circumstance that the Pteria-contorta
Shales, with their well-known blackness, give place comparatively
so suddenly to the pale marls and limestones of the Cotham Beds,
which had obviously a very different history.

Bed 5 6 is again easily found—its hard nodules being covered
with well-preserved fossils. Species of Acteonina and Natica oppeli
Moore are particularly abundant.

The Pleurophorus Bed is richly fossiliferous when found; but
the same cannot be said for the Bone-Bed. This bed is somewhat
disappointing, and totally unlike its equivalent stratum farther
west near Blue Anchor. It is a conglomeratic rock, consisting of
subangular pieces of grey-blue limestone embedded in a greenish,
siliceous, and earthy brown matrix—the greenish siliceous and
micaceous matter also forming an almost pure layer at the base.

The Westbury Beds below stratum 17, with the exception of
the basal bone-bed, were not well-exposed when I visited the
locality, and so I have had to rely upon Bristow & Etheridge’s
figures for the thicknesses of the deposits intervening between
Bed 17 and the Sully Beds. The basal bone-bed is very similar to
that which occupies an equivalent position all along the coast to the
west of Watchet and between that locality and Blue Anchor; but
vertebrate-remains are not quite so numerous here.

A noticeable feature about the Keuper is the scarcity (if not
absence) of layers of gypsum, which are so numerous at Blue-
Anchor Point. Between the base of the Pteria-contorta Shales and
the top of the red marls (Keuper) intervenes—according to Bristow

ee ec ee

26 MR. L. RICHARDSON ON THE RHZETIC OF [Feb. 1911,

& Etheridge—no less than 115 feet of deposit, of which I surmise a
thickness of about 14 feet belongs to the Sully Beds.

Lilstock section.—-The last section to notice in the Watchet
area is that on the coast at Lilstock (Little Stoke, auctt.). From
the stratigraphical standpoint it is by far the most satisfactory, for
the beds are undisturbed by faulting, landslides, or accumulated
talus. The Pteria-contorta Shales are particularly well displayed
and easily accessible.

Lilstock has been mentioned by Etheridge as a locality where
‘the Rhetic beds are developed with great distinctness,’ and he has
also given a diagrammatic section to show the disposition of the
beds in the cliffs around the little bay.* But, except for this brief
notice, the section has been hitherto ignored—probably because of
the difficulty of reaching it. Williton, near Watchet, is the nearest
railway-station, and that is about 7 miles distant.

Having arrived at the cottage by the old and partly destroyed
landing-stage, the observer will notice that the first portion of the
cliff (immediately to the east of the buildings) is just capped by
the Pteria-contorta Shales; while the marlstones of the Sully Beds,
being harder than the overlying shales, have resisted denudation
better and project, forming a prominent feature. Eastwards the
beds gradually descend, and continuing in that direction the observer
will find a place where the greatest stretch of talus occurs, and where
therefore it is easiest to reach the deposits at the junction of the
Cotham and the Langport Beds. It is here that the relationship
of the equivalent of the Cotham Marble to the superincumbent
Langport Beds can best be studied.

Below, but a little farther east, and standing out conspicuously,
are the marlstones of the Sully Beds; and yet a short space beyond,
is the place where the complete sequence from them to the Lower
Lias can be quite satisfactorily studied.

Capping this portion of the cliff is the massive Lower Liassic
limestone, corresponding to the ‘ Bottom Lias’ of Dunball. Its
conspicuousness affords additional guidance to the position of the
section under consideration.

From this point around the little bay the rocks are extraordinarily
faulted; but, as the prevalent inclination is to the south, or some-
what west of south, it follows that by proceeding along the eastern
side of the bay the geologist will encounter lower and yet lower
deposits, until just before the Keuper and Rheetic deposits are
brought into juxtaposition with the Lower Lias by means of another
fault, he obtains a glimpse of the true Tea-green Marls alongside
the fault-plane close down to beach-level.

Returning to the main section, I will deal first with the Sully Beds.
They are easy to examine, well-developed, and more than usually
fossiliferous. Organic remains have been found as far down as
7 feet 9 inches below the base of the Pteria-contorta Shales, so it is

1 Proc. Cotteswold Nat. F. C. vol. vi (1871-77) p. 39 & fig. 1.

Vol. 67. ] WES‘, MID, AND EAST SOMERSET. 27

there that must be drawn for the present the line between Rheetic
and Keuper. Further investigation may lower the line; but this
reduction in thickness prepares us for the fact, that in the railway-
cutting at Dunball the Sully Beds are probably represented by
a bed only 10 inches thick.

The uppermost foot or so of Sully Beds at Lilstock is crowded
with specimens of Péeria contorta, and the topmost layer is identical
lithically and paleontologically with the layer at the top of the
Sully Beds at St. Mary’s Well Bay, Sully. It is impossible to
distinguish between hand-specimens from the two localities.

The Bone-Bed is a very hard, grey, siliceous sandstone, not unlike
the foreshore Bone-Bed at Blue Anchor; but the sand-grains are
smaller, and the vertebrate-remains more comminuted. Obscure
moulds of [socyprana occur, with the tests replaced by iron-pyrites ;
and associated with them are small coprolites, the usual fish-
remains, and a few small quartz-pebbles.

In this country the deposits between the main Bone-Bed (15)
and the Sully Beds, or, if they are absent, the Keuper, are best

described as the ‘infra Bone-Bed deposit, for an attempt at more

minute correlation of their component beds is not generally attended

with very satisfactory results—the strata varying so much from
place to place. However, in so far as Lilstock is concerned, I
have made some suggestions as to their individual correlation;

but it must be remembered that these are only suggestions, nothing
more.

Bed 9 is very conspicuous, and I do not think that there is
much doubt that it is on the same stratigraphical horizon as the
similarly-numbered beds in the Dunball and Charlton-Mackrell

railway-cuttings. Horizon 56—the Cardium-cloacnum Bed—is
not distinctive: at least I did not discover its familiar, fossiliferous

little nodules.

The component deposits of the Cotham Beds, again, agree very.

fairly with their equivalents elsewhere, and there are no signs that
a disturbance affected the ordinary process of their deposition.
The break occurs higher up indeed—at the top of the Cotham

Beds. Here is very instructive and quite unmistakable evidence

that, after the formation of the Cotham-Marble equivalent, and
before the time of deposit of Bed 10 of the Langport Beds, there was
a disturbance of the sea-floor resulting in a remarkable bed consisting
of limestone-masses of all sizes up to 18 inches in vertical length, to
which pieces of Cotham-Marble equivalent are frequently adherent.
In other parts of the section the Cotham-Marble equivalent is joined
on to the hard basal stratum of the Langport Beds.

It should be noticed also that the lower stratum of the Sun-Bed
here, as at St. Audrie’s Slip, is somewhat conglomeratic.

The Watchet Beds are of the same thickness as at St. Audrie’s
Slip, but are usually separated by a limestone-bed from the succeeding
Paper-Shales, which are in turn capped with the massive ‘ Bottom-
Lias’ limestone. :

UPPER RHATIC,

SEcTION AT LILSTOCK.

Limestone, hard, blue-centred; very 1
conspicuous ibe eomtere nah va
Clay, brown, shaly . Ree ee ee, 0
Limestone: 2 to 7 inches............ 0
Shale SL eae ea eas seme Seetiitis,
Limestone, shaly MWR E Re IU OAN Se 0
1
O
0)

See ee

Shale and clay, brown and grey ...
Limestone, blue-centred
Shale and clay, brown
Limestone, very massive, dark grey 1
ee hard, brown, passing down 0

into
peiaties rather shaly in places, : 0
‘$3

but usually a well-marked bed
Limestone, often not a very con- |
spicuous bed, as it passes into a |

f
1 yellowish rubbly deposit, but is -0
§
m

LOWER LIAS.

Shales, yellowish-brown and grey
not so thinly laminated ...........

r
.|
ie

|

always present in one form or the |
other ....... ey)
Shales, papery, hard, ‘thinly Jami- : 1
nated, brown and grey-speckled...
Shales, earthy, yellowish, with 7
0)

—
eee

WatcHEeT BEDS.

i)

thin blue zone at the centre and
a tew onitty: Seams. ....0--5.22) 40:

e

{ Sun-Bed. Limestone, brownish-

grey, vellow exterior ...............

(Shale-parting, brownish yellow.

Nodular masses of a grey-brown

limestone are often present here,

making, with the bands above
2. and below, three beds with marl- -0
partings. Often the top ci
a

0

at ee TN

stone becomes nodular, and com-

bines with the middle layer

O to 4 inches ......

Limestone, bluish- grey, very ‘har d, \

yellowish exterior ; contains |
1 pebbles of a hard compact lime- -0

stone as at Pinhay Bay, near |
L Lyme Regis

oh
o

Marl and hard brownish blue- )
centred rubbly limestone; 8}
“and (+
rather sandy-looking beds ; strati- |
eds nlichaobi soc soft | a meen

ar hard, dark blue, shelly,

DS

Langport Beeps.

inches ..
Very pale. "yellowish- -green.

Ko) ie)

forming a conspicuous bed and a
useful datum-level; ferruginous :
Shoes anchesy: 4) ove enn
Shale, yellowish . Me send a)
Limestone in
brownish-grey,

10.
nodular masses
weathering pale 0
yellow.
inches ..

0 to 18

ey p. Leis

MR. L. RICHARDSON ON THE RHZATIC OF

[Feb. 1911,

Thickness in feet inches.

1 Ostrea liassica Strickland.

=‘the Clogs’ at Dun-
ball.

Volsella minima (Sow.).
: =‘lLias Paviours’ of
Dunball.
=‘ Bottom Lias’ of
[ Dunball,

Paper-Shales.

die t|H

- © NWwWAWee aD

ay—

6 O seen.

0 Volsella sp. (crushed).

1

6 Ostrea liassica, common
in the blue zone.

Ai AO
5
(Very variable beds: 1 &
| 3 should be found first,
9 J and then the inter-
| vening portion can be
| made out. Ostrea lias-
L siea.

( Dimyodon intus-striatus
| (Emmerich), Volsella

4< minima (Moore non
| Sow.), Plagiostoma va-
\ loniense (Defrance).

‘Rubbly Beds.’ Fossils
of Bed 8; and, in addi-
tion, Protocardia rhe-
tica (Merian).

Or

bo

& dk

UPPER RHATIC (continued).

LOWER RH ATIC.

r-

Cornam Beps.

—_—— — _ c_

Vol. 67.]

Ba}

el

WestBury BEDs.

[Linstoc

[ (1)

5ad (2)

(3)< hard-looking layers ;

gp No

s©

10.
ils
12.

13.
14.

15.

16.

WEST, MID, AND EAST SOMERSET.

Cotham- Marble equivalent. A
splintery, brownish - grey lime. bo 3
stone: 0 to 6 inches
( Marls, non-laminated above, more )
so below. In places, at 18 inches
below the Cotham. Marble, is a
hard, grey, sandy fine - grained {
1 limestone, and above it occur
several thin brown layers. The
topmost portion of all is conspicu-
ously streaked brownish-yellow ..

ey grey, fissile and rather

sandy, not always conspicuous, a
but in places harder and non-
PSS ewe ee eee MR, el oN
Marls, bluish-grey, with a few
not vely conspicuous sandstone ( 4
layers. More indurated in a zone
at the top
Limestone, grey and yellow, sandy,
with a little yellowish mas |
matter intervening

Se a ei ei ee ey

Oh. ea

Shales, black, with gypseous aggre- }
gations. At the top (for 2 or 3
inches) these shales are more
LTH) Gh (ee RAMOS Oe As LG eee ae

| Limestone, grey, which (together
with a large amount of ‘ beef’) ¢-0
| spalzes up a hard zone .

(Shales, black, laminated. At. the )

| top (2 inches therefrom) are two !

but these, 2
| on closer inspection, are found to }
| be bound together by selenite J

(

( Limestone, blackish-grey, earthy, )
| in three beds with shale-partings ; |
+ sometimes in two when the shale- -1
parting is thicker. On the top is a |
fairly regular layer of ‘beef’ ...... a)
Shales, black, laminated, with two
layers of ‘beef’ (conjoined) io} 6
inches from the base ......... about
Limestone, pale grey, usually hard
} and often nodular in appearance ; i 0)
‘beef’ on the upper surface.........
Shales, black .. Bays Sohal
Sandstone, grey, calcareous .........
Shales WIAGkan ere os octet icons:
Limestone, dark grey, although )
conspicuous in some places it thins Ly
+ out in others to a thin brown soft
seam, barely an inch thick: 1 A
5 inches

Thickness in feet inches.

29

Fish-scales (fragments).

11

0 Pteria contorta( Portlock).

-

Chlamys valoniensis
(Defrance).

Protocardia rhetica.

Chlamys valoniensis,
Pteria contorta abun-
dant in the shale-layers ;
Gyrolepis alberti Ag.

Usual Rheetic fossils.

Gyrolepis alberti.

Shales, black, laminated 1 6 ( Gyrolepis alberti, Hyb-
grey, slightly pyritic, and mica- 0 6 J a a a
ceous at the base, becoming more STM AT TGn Cy arian
of a limestone above.................. L T an YP

Shales, black, thinly laminated, ‘of
2

coming greenish-speckled: 26 to

|

\.

Bone-Bed. Sandstone, very hard,
} 32 inches

casts.

LOWER RHATIC (continued).

-e oO OC Ct i

Suuty Bens.

30 MR. L. RICHARDSON ON THE RHATIC OF

(LiLstTock.)

|

Shale, indurated, selenitic.
(1) Bea?
17.< (2) Shales, black, with gritty layers: eeO
(3) 1 Sandstone- layers, thin, grey, mixed ‘ 0
with shale and much selenite otens
(Shales, black, thinly in ay
0)

‘ Bone- 0

with a number of thin gritty

seams—especially at the base......

Limestone, grey, shaly, but ol
0

—<—$—<—<—=

18 and dark grey in Pee 4 to
Giehes .....;
Shales, black,

‘laminated, green-

speckled, with much selenite Betas u

Limestone, hard, greyish, in lenti-
cular masses, somewhat nodular :
| maximum .. 5.2

Shales, black, ver ry selenitic ; 23 to sto} 9

0

WestzBury Bens (continued).

le Bifeat et,
Limestone, ver y hard, with black
nodules) (24.
ie Shales, black, becoming g ereen along
24,

KS

the lamine.. wee
(2) Thin gritty layer Pe ree Mins.
(3) Shales, black

L

oo

. (Impure, bluish-grey, shelly, sandy )
limestone, micaceous in layers
with shale-partings. The top
layer is the most massive, the

it others being thinner and having +0
very thin shale-partings. <A

little more to the east brownish-

green, very shelly, impure lime-

| stones predominate aa

2. Shale, black and brown .......

Marlstone, greyish, shelly. “The
tests of the shells having ee

3. < (in most cases) dissolved,
| cavernous appearance is impel |

| to the bed .

| id ereenish - yellow ‘and =)

A,

hard in ee at the top
MINED AHNTVGC) AHOMB Boeke nee
Marlstone, dark, ereyish, with a
tinge of green. "The lower por-
tion divides up into four rather

a
Or

regular bands........
g { Marl, greenish- yellow
; more rubbly “S02.
( Marlstone, greenish - yellow fe
black at the base. Usually divides |
J into two main beds, with a thinuer pl
| layer—the darker portion—at the |
(eibase ec saat haat Pee eee y

‘and Gar KY

a

( Marl, dark yellowish-green and

KEUPER. 9 “blackish.

[Feb. 1911,

Thickness in feet inches.

Coprolites numerous,
Hybodus minor, Gyro-

fi lepis alberti (scales and
3 ? teeth).

2

6

- § Isocyprina ewaldi (Bor-
2 nemann).

9

5)

9 Pteria contorta.

2
4
Os
3
a2) 0
(Pteria contorta very
common, Volsella sp.

indet. and much shell-
débris, Gyrolepis al-

103< berti, Sargodon tomicus
| Plieninger, Lepidotus ?

(teeth), small Plesio-
| saurian tooth, quartz-
| pebbles.

1 ae contorta com-
2 ¢ mon.

3 Fish-scales (fragments).

10 hinge Protocardia (?),
fish-scales.

4

3 Shell-débris, fish-scales.

Vol. 67.] WEST, MID, AND EAST SOMERSET. 31

(2) Mid Somerset.
(A) The Polden-Hills Area.

(i) Introduction.—The name Polden Hills is popularly applied
to the noticeable ridge which presents a steep face south-westwards,
but a gentle dip-slope north-eastwards, and, starting near Dunball,
about 2 miles north of Bridgwater, runs in a south-easterly
direction certainly as far as the Butleigh Monument. But, beyond
that, it is doubtful whether popular opinion would permit of its
extension. Considerable research and abundant enquiry have not
forwarded matters: so—in accordance with the precedent set in
the delimitation of the Cotteswold Hills—I may suggest that a
definite contour-line be taken, and in the present case the 100-foot
contour-line would answer the purpose best. The higher ground
thus contained extends from Dunball to the neighbourhood of
Charlton Adam, and is excellently shown on Bartholomew’s ‘ Half-
inch-to-a-Mile’ map of England & Wales—Dorset (Sheet 34).

At Dunball at one end of the area, and near Charlton Mackrell
at the other, magnificent sections have been displayed in railway-
cuttings. ‘The section at the former locality is still open, for its
steep sides afford but little roothold for vegetation ; but the section
at the latter locality, with its sloping sides, is—despite its recent
construction—almost wholly obscured. In the intervening district,
as at Windmill Hill, Butleigh, higher strata (belonging to the Lower
Lias) are well exposed.

The stratigraphy of the Rhetic in this area presents several
points of difficulty, which additional detailed local work, aided, per-
haps, by purposely-made excavations, can alone thoroughly elucidate.
The main difficulty is encountered in connexion with the Langport
Beds. At Dunball they are only 4 feet 3 inches thick; but at
Charlton Mackrell, 20 feet 8 inches. There is not sufficient evidence
available to show in precisely what manner this thickening has
taken place: whether it is due simply to overlap on the part of the
higher beds over the lower from east to west, or to some more
complex cause.

In the Dunball-Ashcott portion of the Polden Hills, it would
appear that the Langport Beds do not differ widely from their
equivalents in the railway-cutting at Dunball. That is, they are
thin, and the bottom massive limestones of the Langport Beds,
or the ‘Sizes’ as they are locally called, cannot be definitely
recognized. All the limestone-beds present appear to belong to
the upper portion of the Langport Beds: in other words, the
‘ Sizes’ may be wanting, or very poorly represented, in this Dunball-
Ashcott district. Their absence or poor development may be due to
the fact that this portion of the Polden Hills during the time of
deposition of these beds was rendered unstable, owing to movements
along an old anticlinal axis, which is now traceable at Blue Anchor
Point, enters the Polden Hills near Knowle Hall (to the west of
Bawdrip), is seen in the railway-cutting near Cossington, and

32 MR. L. RICHARDSON ON THE RHZTIC OF [Feb. 1911,

emerges again near Greinton, to be re-discovered at Camel and
Sparkford Hills, which are probably part of its northern limb.
If this axis is traced on a geological map, the suggestion presents
itself that it is connected with the series of folds of which the
Mendip Hills is one, such an equidistance therefrom does it preserve.
In this area the sections that should be visited are those in the
railway-cuttings at Dunball and Cossington and in the quarries at
Catcott, Windmill Hill, Butleigh, and Butleigh Hill. The following
table shows the thicknesses of the several subdivisions at the two
ends of the area—at Dunball and Charlton Mackrell.
TaBLE III, 1nLusTRATING THE THICKNESSES OF THE SUBDIVISIONS OF THE
Ruztic SERIES IN THE PotpEN HILts.

Approximate thicknesses in
St. ins. at Dunball and in ft. ins. at Charlton.

ag Pe Wateheitiseds™ rf. ee Sie ees | ae ee absent.
3 i II. Langport Beds ............ flo. het ae 20 8
Bi) TSUN. (Conk BAIS Ego. 0.) AlygS are We et 4 9
fe | = IV. Westbury Beds............ 32 2 ha ga 22 4
Ls is Sully Beds 0.00.00... Dp a0up seen absent.

Gi) Stratigraphical details.—The deep railway-cutting at
Dunball, the ‘ Puriton Section’ of Bristow & Etheridge,’ admirably
displays the sequence from the Grey and Tea-green Marls to the Lias.

The Grey and Tea-green Marls are exposed on the west side of
the cutting, at the commencement of the wall. Black shales are
seen above, up to a prominent limestone-band—Bed 9. This bed
is more accessible on the other (eastern) side of the cutting, where
indeed there is a continuous sequence up to the rubbly limestones
of the Langport Beds. Half-way towards the first bridge is
seen the Sun-Bed, succeeded by the presumed equivalents of the
Watchet Beds, which are in turn followed by the Paper-Shales ;
while heyond—on the same side of the cutting—come Liassie strata.
The last, however, are better exposed on the western side.

The only published record of the Dunball section which contains
original information is by Bristow & Etheridge, and from it
the present record differs in but a few minor matters of fact.
An abbreviated edition of Bristow & Etheridge’s record is given
in the recently-issued Geological Survey Memoir on ‘ The Geology
of the Quantock Hills, &c.’ (1908, pp. 70-71), where it is stated
that Messrs. J. H. Blake, W. A. E. Ussher, & H. B. Woodward
remeasured the section ana apparently discovered no discrepancies.”
They make no advance, however, in the matter of subdividing the
Rhetic, not separating the greenish-grey marly beds below the
Cotham Marble from the ‘ White Lias.’

The massive ‘ Bottom Lias’ is at once noticeable. No limestone
is recorded in the official section as parting the Paper-Shales from
the presumed Watchet Beds. Probably it was absent from the

1 Vertical Sections, Sheet 46, No. 1, Geol. Surv. 1878. :

2 See also ‘Jurassic Rocks of Britain—The Lias of England & Wales
Mem. Geol. Sury. vol. iii (1893) pp. 81-82.

UPPER RHATIC.

Vol. 67.] WEST, MID, AND BAST SOMERSET. 33

place at which Bristow & Etheridge measured the section, or
it may be that the shales were not sufficiently calcareous or
indurated there to assume the aspect of a limestone-band. These
geologists apparently recognized the equivalent of the Cotham
Marble, but recorded only a few inches of shale between it and
the next underlying limestone, instead of somewhere about 2 feet
2 inches. True, this shale varies somewhat in thickness. This is
the main difference, as regards stratigraphical details, between our
records ; the other differences are so trivial that a prolonged com-
parison is unnecessary.

SECTION IN THE RatLway-CotTtine AT DUNBALL, NEAR PuRITON.
i} Thickness in feet inches.

. Shales, hard, dark-grey, occasion-
2 ally hardened into stone. (‘ tins _ Volsella minima (Sow.).
= BaOUES: ects coeicn ee ae as:
- : Bottom-Lias.’ Limestone, mas- Pl hej
64 sive, evenly-bedded, Dias, f 1 1 ; sia PACHOME OMB ELY
= ar eillaceous 2 nae
= {a shales, hard, “pale grey and iG
S brown: 22 to 26 inches BR ra Pree } Paper-Shales; locally

Limestone, dark grey, rather earthy, > termed the ‘Burning

frequently passing into shale. (9 4 j Scale.’
penal however, it is a noticeable

3 3 seen.

Shales, grey, calcareous, more fissile
here than usual ; 3 feet 6 inches to os 10 ;

Amteet 2MINChes as ete eee eee ‘Black Scale.’

BEDs.

3 610

Sun-Bed, Jew, or Dew Stone. }
Limestone, very massive, greyish-
brown, conchoidal fracture, with | -
frequently a hard marly limestone -0 11
3 inches thick, called the ‘ Slippery
Bed,’ separating off from the top:

L 10 to 14 inches .........

0) 8)

Rie

Kw)

=
Shale-parting, sreyish-green, marly.
Limestone, massive, with a con-
| choidal fracture, bluish - “i 9
hearted: 8 to 10 inches .....
Marl and very pale grey rubbly
limestones. Sometimes the lime-
; stones are more prominent, parti-
cularly one near the top .....
Limestone, dirty grey, rather ear thy
} and irregular, with a hard cap: 1
25 to 55 inches ......
¢ asl, nae grey, and thin- fo
limestones : 23 to 4g inches ......

non Sow.).

0 Ab

Laneport BEps.
Go

Limestone, bluish-grey hearted, Mh
lowish exterior, soon breaks up .

=|

e ae
8. Shales, pale grey, marly............... 0 3 Vee, t Works. ]

Wart
zs ge

Locally the ‘Cement’ and

0 4 { Volsella minima (Moore

Pleuromya crowcom-

beia_ auctt., -common

0 i 3 im, the lower portion ;
| Plicatula hettangiensis

bes indurated at the

; ee ules eee ane) ale 0 3 these beds are frequently
ees bev ettrtnieate Beer inied sa fora vane
10 ; ci ne be andusdted, oF bo 2 stratum, 8 inches thick.
11. Limestone, hard, dark grey ......... 0 13 = to 3 inches. |
° ; 4
@. J. Ge S.No. 265. D

es

©
i

MR. L. RICHARDSON ON THE RHATIC OF

[ Feb: tora,

[DunBALt. | Thickness in feet inches.

= Shales, dark green, clayey.. 8) 2

S Cotham-Marble equivalent.

SS es als | Limestone in intermittent imc to

8 ticular masses: OU to 2 inches ...... ;

S i 9. Shales, calcareous, pale greyish- 9 9 fl feet 4 inches at the

aes green, weathering white ............ Cement Works. ]

SG} mR 3. ‘eee wee greenish-grey, 0 9 {i inches, and in three beds

3 = 4 crystalline: 1 to 2 inches ......... ‘ with shale-partings. ]
Shales, greenish-grey, thickly lami-

am a abe nated, ‘aleameane: 4 to 9 fe Near. 4 77a

me LS ;

6) Limestone, hard, greenish-grey, Pleurophorus angulatus
ma (2) passing into a fissile limestone Moore (teste Bristow &
= with quartz-grains in the top Etheridge).

: layer: 6 to 10 inches ............... [4 to 10 inches. ]
Shales, black and brown, ferru-
(3) ; oinous .. . about . 0 6 [Ato 6 inches.]
4, 5
Pteria contorta (Port-
(1) Shales, black 3 0) } lock), Isocyprina ewaldi
(Bornemann)..
Fish-scales, shell-débris,
(5a. (2) ee earthy, very ferruginous, 0 1 Chlamys __valoniensis
with ‘beef’ and selenite ............ hatice (toe aN
rhetica (Merian).
(8) Shales, black: 22 to 26 inches ...... 2 0
Limestone, hard, grey, irregular
shghtly pyritic, with some ad-
5 b. mixture of shale: 1- to 2-inch 7-0 6
L layer of ‘ beef’ on the top. ry
stone, 4 to 8 inches ......
6 Shales, black, weathering brown, ya 0
; selenitic: 12 to 14inches .........
Limestone, grey, very earthy,
shelly, slightly pyritic, with a 0 i
7. #-inch layer of ‘beef’ below: Y Sd LESLIE 20S, 240.
2 to 4 inches .......
(1) Shales, black, laminated ............ 2 4,
(2) je indurated, very selenitic, 0 9
8. simulating a hard band . ,
Shales, black, thinly laminated,
(3) f selenitic ........ :
( Limestone, massive, -greyish- ao
somewhat nodular (of septarian
formation), im places siliceous, .
traversed by ramifying fissures © Wnty. >
filled with calcite. This bed ree ee ee
9. much resembles the Bone-Bed -O 10 cham» <cemen ae
at St. Mary’s Well Bay, Sully. P ;
The topmost 2 inches comprise
indurated earthy and selenitic
(5 shale with impure limestone:
= \e 9 toad ainchesis 0) 4) See ee ‘Pullastra and Axinus
= eee LO, Shales, black, thinly: laminated ... 2 6 ! elongatus’ (teste Bris-
es an] tow & Etheridge). q
mm) eH Acrodus minimus Ag.,
a er Limestone, grey and black, earthy ; | Gyrolepis alberti Ag.,
Fe a fl much selenite and ‘beef’ on the 4 2 Saurichthys acumina-
ie a ; under side. Passes into a very i) tus Ag., Hybodus minor
“a te fossiliferous bone-bed . Ag., Lepidotus ? (teeth),
ea] Shales, black, nfoinents lami- aah ts mes Copmaliess
= 12 nated, but not quite so much il eae contorta, Proto-
= | ; a the base. Very selenitic at cardia rhetica. —
EME GOP cs saceaeed Meee RRR Eee eee
Thin sandstone-layers, mixed with :
13. ; a preponderant me A of shale.. 3, 3 Mish-scalles:
4 ieee black, selenitic om an 8
: crystals) .. Pacts

LOWER RHATIC (continued).

Vol. 67.| WEST, MID, AND EAST SOMERSET. 35

[ DoNnBALL. | Thickness in feet inches.
Ti ee grey, mica- € 9 —3.‘Fish-scales. [1 to 3 inches. ]

| i.
(1) Shales, black, thinly laminated ... 0 6
Shale, extremely selenitic, ferru- :

(2) OWE

1

16. ginous, simulating a hard band..
(3) (sie black, thinly laminated, } 1
gypseous aggregations ...............
(1) ; Limestone, dark grey, impure, ‘ 0 3
arenaceous : 2 to 4 inches .........
V7 (2) Shale and thin sandstone-layers ... 0 1
: Limestone, hard, dark grey, arena-
naceous, ‘with argillaceous con-

cretions of pyrites in lower part |

be

CHER Erg ee) Ri aie ee Sahl sy ne

18 ae black, laminated, with

several thin, grey, fine-grained,
micaceous sandstone-layers near
the ops oclemite. 022.2 -.-, ces

4, A

WestBury Bens (continued).

) :
| Pteria contorta, Proto- H

f
93. Sandstone, pale grey, non-calca- 0 OL : cardia rhetica. i
reous, dense, fine-grained ......... Up {|
24, Shales, black, laminated...... about 3 6 | it
Sandstone-layers, greenish-brown, i
micaceous, ferruginous, earthy, 0 I
mixed with a preponderant amount |
of shale aiavahelsloceratataialaefolal sinlaliatn} nt atejolterscstols iste = 32 2
He |
5a Dull yellowish-green earthy sand- 0 10 ee contorta (teste
Boa stone, slightly ferruginous ......... Etheridge).
Che
L 0 10
Ina ? Non-sequence.
|
a (" Marl, sandy, greenish-yellow ...... 0) 4, |
3 Marl, hard, greyish-yellow ......... 0 8 i
o Marl, less compact, darker yellow. 0O 2
a at Marl, yellowish-green, argillaceous, i
Sy, NEE RS GAS Ae Ce eae Tone
=) as Marls, de yellow, dark green, 3 4
S z = Snide lala Saat tere.
be ibVeird onal css tose ce woes eee eee 0 7
S Marls, dirty yellow, mdurated in
5 ( Places Ret tnt ese ee

Comparing this section with that already described at Lilstock,
we shall first of all notice that the Sully Beds have become greatly
reduced in thickness, and that at Dunball a 10-inch bed below the
Black Shales is tentatively regarded as representing their upper-
most portion. The thickness of the Westbury Beds at both places
is about the same. Bed 9 is an easily found limestone, and at
Charlton Mackrell was noted at about 15 feet above the base of the
Black Shales.

At Dunball the principal bone-bed appears to occur at a higher
horizon than usual, being the bed numbered 9; while the bed that
is presumably on the horizon of the main Bone-Bed (that is, 15)
contains but few vertebrate-remains. ‘The Cotham Beds at Dunball
and Lilstock agree very well, and so do the Langport Beds ; but the
Watchet Beds are not typically developed, and some care has to be
exercised in separating them from the Paper-Shales when the dividing |
limestone is not distinctively developed. oa

Close to Dunball Station are the Cement & Lime Works. As |

D2 |

36 MR. L. RICHARDSON ON THE RHZATIC OF (Feb. 1911,

the deposits that are principally sought for in the workings are the
Planorbis Beds, which lie towards the foot of the northern slope of
the hill, a number of deep cuttings and tunnels had to be made, in
order to allow of the passage of the trolleys from the workings to
the kilns. The steep portion of the hill is thus literally sliced
through, and a magnificent series of sections made available.

As might be expected, the differences between the beds exposed
in these sections and those seen in the railway-cutting are trivial ;
but I have noted the more important of them in the railway-
cutting section, giving the information in square brackets.

North of Bawdrip the rocks are affected by two approximately
west-and-east faults, but their prevalent southerly dip is obvious,
and is still more so in the fine railway-cutting on the way to
Cossington Station, at which place the Black Shales of the Lilstock
Beds reappear, forming the central portion of an anticline.

Cossington railway-cutting.—Mr. J. F. Mostyn Clarke,
A.M.I.C.E., has described the sections on this railway, obtaining
the details which he recorded as the construction of the line
proceeded.'

When Mr. H. B. Woodward visited the section, he was accom-
panied by Mr. Clarke. Mr. Woodward noticed a bed resembling
the Cotham Marble in texture, but did not attempt any detailed
separation of the deposits, nor did he indicate in his record where
the Pteria-contorta Shales ended or the ‘ White Lias’ began.

The details appended below were obtained in the eastern bank of
the cutting, alongside the goods-siding. A greater thickness of the
Black Shales was formerly exposed, but talus has accumulated and
has hidden a band of nodules that probably corresponds to Bed 9 in
the Dunball section.

SEcTION In CossineTON RAatbway-CurtTine.

Thickness in feet inches.
Laneprort ¢ Limestone in two beds, rather rubbly in
BEDs. between: jsiccin 4. .s8o.o bo peeenmeny Seen yal 0

1 O seen.

( Clay, brown and dark grey: 2to4inches 0 3
a | Co fhm Vila billie aan eee 0 2
a 2. Shales, yellow and grey marly, very
a Clayevaatibhestopi a. Gee eee 0
e 3. Limestone, hard, with a nodular bed
< OCEANIAN NN? OLN 1H NE) UO] Dai5cdh con acc uonese dor 5
fm ((1) Shales, pale-yellow, marly ......... O 4
£ | Jiimestone: 2 to 4 inches............ 0 2
2 (2) Shales, yellowish: 0 to 2 inches... O 1
A., Limestone, rather ‘ flaggy’ with
clay in the bedding-planes......... 0 a
(3) Shales, yellow and brown, clayey. 0O 3
5 3

* Proce. Bath Nat. Hist. & Antig. F.-C. vol. vii (1891-93) pp. 127-36
[& section].

Vol. 67.] WEST, MID, AND EAST SOMERSET. 37

[CossINGTON. Thickness in feet inches.
((1) Shales, black, laminated ............ 2
Limestone, earthy, ferruginous ... 0 13 Saurian bone.
Shale, black: 1 to 2 inches ......... 0 irs Ch neo nee
5 a.< (2)< Limestone, shelly, nodular: 0 to Deka a es
wz Ay WGHES Sor Ge ON, os nse oh 0 25 (Defrance).
fa) 2
=] RO bits SR ee te ee 0 its
7 (3) Shales, black: 12 to 18 inches .... 1 3
is 5 6. Limestone, earthy, shelly, with ‘beef’
2 On; Che Cops eee eee oon ese: 0 6
BA GO nales pincer ke nh eat. OE ®)
a 7. Limestone, earthy, with one or two
= layers of ‘beef’ on the top ............... 5

Su ialess Wlaeke ee eek eee oe wee coeds

6 3 seen.

Indications of lower beds were obtained on the escarpment at
Cock Hill, where, at the point at which the by-road from Chilton-
upon-Polden leaves the main road, an excavation made in connexion
with extensions to a house revealed Black Shales with pieces of rock
full of fish-remains (Bed 15).

The rock was of two types. The one was a black indurated mud with Acrodus
minimus, Gyrolepis alberti, Saurichthys (2), small coprolites and quartz-pebbles—
very much the same as the fossiliferous indurated black shale above the Bone-
Bed at Lilliput, near Chipping Sodbury, Glos. (see Q. J. G. S. vol. lx, 1904,
p. 197). The other type was more of the typical Bone-Bed facies, being a hard,
grey, micaceous sandstone, as at Charlton Mackrell and Langport, with the
usual fish-remains.

Almost in front of the ‘tower’ a road descends the escarpment,
and in the area between it and the Bridgwater Road were found pieces
of a yellowish micaceous sandstone-layer similar to Bed 19 at
Langport.

In the neighbourhood of Edington and Catcott there are three
quarries in work, namely:

(1) the ‘Catcott Quarry,’ which is situated just over half-a-mile south-by-

east of Catcott Church ;

(2) the ‘ Edington Quarry, which is about half-a-mile west-north-west of

Catcott Quarry; and
(3) another quarry, a little over a quarter of a mile north of the latter.

In the first two, the uppermost beds of the White Lias proper
are seen with the basement-beds of the Lower Lias above them;
while in the third, only the White-Lias ‘ Dew-Stones’ occur.

Some care is required in fixing the line of demarcation between
the Rhetic and the Lias in this neighbourhood; but the White
Lias proper is only thin, as was shown by a very interesting section
in a quarry in a field by the side of the Bridgwater Road, about
half-a-mile north-east of Greinton. When I first visited this section,
the quarry was being worked along the strike of the beds and also
along a fault-line. On the south side of this fault were the Lower
Liassic beds and the Dew-Stones—the beds nearest the fault being
vertical, but the others soon declining away from it. On the other
side of the fault, the Cotham Marble was seen bent round in a
peculiar horseshoe curve. On my next visit the quarry had been
developed, and this interesting bit of faulting obliterated ; but the

LOWER LIAS.

38 MR. L. RICHARDSON ON THE RU ZETIC OF [Feb. rorr,

Cotham Marble could still be seen, with its peculiar tough clay-bed
above.

Glimpses of certain of the Rhetic deposits have been obtained
between Lower Pedwell and the Somerton Road, and details are
recorded in the Geological Survey Memoir.’ The only matter of
note is that ‘shelly limestone similar to the Wedmore Stone’ was

observed in a ditch-excavation near a new house west of Ashecot.?

Windmill-Hill Quarry, Butleigh.—At Windmill Hill,
close to the Butleigh Monument, is an important section. It is
important because the sequence of beds is identical with that which
was only temporarily exposed in the railway-cutting at Somerton
to be noticed shortly ; and, while the latter is probably already
obscured, the former will remain open for certainly some years to
come, as the quarry is ‘in work,’

SECTION In WINDMILL-HILL QuARRY, BUTLEIGH.

Thickness in feet inches.
42. Limestone, somewhat nodular, débris of. 0 4. Ostrea liassica Strickland.

Ais Clay, oreyish-oreeniog ano eee 2
AO. Limestone, rather flaggy...... were. FO) 3
39. Shale, brown and grey, laminated ......... 0 5
38. Limestone, grey and brown, fissile ...... 0) 4
37. Shale, brown andere? ti Peer rae tO
36. Limestone, fissile jorey, Seek ee
35. Shale, pale- biowitl: ec at eee aaee ence 0
34, Limestone, pale-brown and grey ...... 0

33. Marls, greyish-green with a whitish zone. 1
32. Limestone, pale blue-grey, yellow exterior 0

3] ; Shales, with a conspicuous brown seam 9
mear the ;centrei.. 3... Mein tae See

30. Limestone, dividing into two beds ...... 0

Qos shale wpalengic. cies os Sie ee eee eee 0)

28. Limestone, rather massive [8 | Ort

a Shale, brown and grey-blue [clay 5]. i eee 0

Limestones, two beds: 6 to 10 inches 2 (ga
26. § [one bed in the Somerton cutting} is CEES A
25,4 pale-brown and blue-grey, passing |
in places into limestone [7] .
24. Limestones, two beds with shale- partings
23.4 Shale, pale- brown and blue- -grey, with a
half-inch limestone-bed [5]
is aa three beds with shale- Bae
ings (7 : :
21. Shale, wee [par ting]
20. Limestone, hard blue [6] . 0
19. Shale, brown boil: eee 0
18. Limestone, Mmard, PLUG gas) .9.1. cc ee LO
ie “Sltalee 002) imches an) eye as eh eee 0
0)
0)
1
0

Lignite.

16. Limestone, hard blue
15. Shale, blue and brown; 3 to 5 inches [2]

Aaa Blue Clog.’ Limestone, massive blue.
13. Shale, touch blue .. :

OoOoroTrFFbNEYNH NH NOD DMNOND © OWHLWHED

Ostrea liassica.
Hemipedina-radioles.

fon)

ie Limestones, bluish-grey, with but very 9
10 Chin parties) seenen ny eee

1 ‘Geology of East Somerset & the Bristol Coal-Fields’ (1876) pp. 85-86.
2 Ibid. p. 85.

Vol. 67. | WEST, MID, AND EAST SOMERSET. 39

One of the most noticeable features in the landscape of this part
of Somerset is the Butleigh Monument, raised to the memory of
Admiral Sir Samuel Hood. In its neighbourhood the ground is
very much faulted, the Lias being on a level with the Red Marls.
This is easily seen from the high ground near the quarry, at the
cross-roads north-west of the Monument. On the left is the quarry,
and by the side of the road, facing the observer, appear the Keuper
Marls. Tea-green Marls are poorly exposed in the path below the
Monument, and Cotham Marble has also been observed (loc. cit.).

Dunden-Hill outlier.—Dundon Hill is a very conspicuous
outlier to the south-west of the Butleigh Monument. On the
snmmit are two quarries, but the strata are very much disturbed,
being at the south-western end of the south-western quarry bent
into several little anticlines. The prevalent dip is south-east-
wards. The highest bed seen in the Dundon quarries is that corre-
sponding to Bed 34 in the Windmill-Hill Quarry. In the road
leading up the hill from Compton Dundon, the Red and Tea-green
Marls are finely exposed: then there are traces of the Pteria-
contorta Shales; but by far the most interesting discovery was that
of an exceedingly well-bored, nodule-shaped mass of Cotham
Marble in its proper stratigraphical position, with numerous
specimens of Dimyodon intus-striatus adhering to it. The borings
are crypts of Lithophagr. :

Butleigh-Hill Quarry.—Continuing along the Charlton-
Mackrell road from Windmill Hill, the observer will notice two
quarries, both on the north side of the road, and about half-a-mile
apart. The first is about a mile distant from the Monument; but
the second will be considered first, because it affords the better
section.

In this quarry many of the limestone-beds are rich in pyrite,
which, when decomposed, gives rise to cavities that impart a very
cavernous appearance to those beds.

SEcTiIon IN BUTLEIGH-HILL QuaRRy.

Thickness in feet inches.
ime ( Limestones, whitish, in three layers, }
se the median being the thinnest. |
Owing to their proximity to the 71 1
ae they are somewhat broken

LAneport Beps.

sp. indet. Volsella minima.

Marl, greyish- white, with an n earthy : Ons
impersistent limestone- edie ci eye
ie Limestone, white .. 0 A
18. Marl, ereyish- white, clayey _ ante 0 1
19. { Limestone of a grey tint, and rather t 0 Te
GENET a Ostrea liassica Strickland,
20:9 ae greenish- -grey and brownish, ho af Protocardia, Volsella mi-
Clayey meme oe es Mt Neeaag cf ; ie
ay, { Mmestons hard, blue and peo 3 nage \ Moore).
centred, cavernous appearance... Ostrea liassica. O. ch ir-
22. Marl, greenish-grey and white ...... 0 a regularis WWianstor Dimyo-
23. Limestone, rather earthy ............ 0 3 Hon ey tue eihiatis (Em-
24, Marl, whitish and often pale-brown. 0O 6 merich), Plagiostoma valo-

| niense (Defrance), Cardinia

UPPER RHATIC.

———

40 MR. L. RICHARDSON ON THE RHZTIC OF {Feb. rg11,

[Burteres Hi11. |

S ios Limestone, whitish-brown, dividing
3 into two beds of which the ies <<
S is very shelly . Javihist C e
s | 26. Marl; 5 to 6 inches.. ees 2 SiG)
S | 27. Limestone, white, earthy see 0
2 28. Marl, greyish-green, laminated ...... 0
ce
A Inimestones and marlin 1
= S
& | 33. Limestone, irregular, blue-hearted. 0
fe | 34, Marl, indurated: 3 to 5 inches 0)
ym | 3b. Limestone, irregular; 4to 6inches. 0O
3 36. Marl and stone: 1 to 2 inches ...... 0)
37, ae whitish, soon breaks up: 0
8:to TO INCHES ets. eee eee
38. eae impure (6 inches), and 0
mach oye

39. Limestone, massive, white: ee el

Thickness in feet inches.

10 §

eT OPRTEE WO HN

Pleuromya crowcombeia
auctt.

re crowcombeia,

Amberleya (2).

Charlton-Mackrell railway-cutting.—The next section
to be noticed is the extraordinarily fine one that was opened out
during the construction of the Castle Cary & Langport Railway at
Charlton Mackrell. It has been briefly referred to by Mr. H. B.
Woodward '; but Mr. E. T. Paris and I spent a considerable time in
studying it in detail, and the following record is the result :—

Thickness in feet inches.

SEGn ies Sets Shei) eerie eee
Marl, yellowish: 8 to 10 inches ... 0
Limestone, fissile, grey-brown ...... 0)
Marl and thin limestones ............ 0)

{ Limestone, grey, fetid, very regular ; 0

Relay flaggy limestone :— 0

Dede tr. ck es ea ee ee epee

LOWER LIAS.
a

Non-sequence.

Ree Limestone, soon 0
breaks u 4 :
Da bec iseth 8 eee aie eee \
Shale, marly, often indurated ...... 0)
Loe very regular. ‘ Block- 0
Beds. ;
Rubbly limestones and marls ...... 1
{rds often divides into =e
|oy2(0 CHERRY Pane kes Seay eek
Shale .. Ua ie reNe 0
Limestone, : WMASSIVE! nes scee ee 0
Shale, marly TELE abe Geel ea en antes 0
(Hee. often separates pas
two dbeds.. 5 eae ee eee
Shale-parting 0s te ae eee
Ake Timestone.® fins eee eee Creer
LIP AES 1 OF) WARNE oi ins ea Bile eS
ILS Me eal Gib notes oy cl spamrenn nia Ds cry lsen Mares,
1A alee.; 0. se cosa ean eee cat eee
15. Limestone
16. Shale .. :
17, Limestone, irregular WE
1S SCE RR ims RIAL SNA Seen

SO OO Se Os aoe ae

ooooco°o°ooceoo ©

PT) SS Ce ae ARR eset ks SEONG Se,
es Se hard, conchoidal frac- ; d
PCa ROUTE CREM CIN OUS® PE .an.c he. c eae eee
22) Meniwandy limestone... ee amo
23. Limestone .... Meee rere eben sO
24. Limestone and shale ................ 0)
OF. aaa very ferruginous es ae
the joints 1d caet ecg ones

Laneport Beps.

ae —_—_—————,
—
©)

2

10

1
11

Bor

NS ©
ae

NEN BIR SH

SF PND WwW HNOMNHEWONDS
oH bo

Ostrea liassica Strickland.

Volsella minima (Moore).

Ostrea liassica, Volsella
minima.

Ostrea liassica.

1 *Summarv of Progress for 1904’ Mem. Geol. Surv. 1905, p. 165.

UPPER RHATIC (continued).

ee eee

lm

Cornam BrEps.

Vol. 67.] WEST, MID, AND EAST SOMERSET. 41

26. Rocky marl . 0
Limestone, massive, ‘often in n three)

layers, the top and bottom layers
being very shelly. Towards the

a 97 eastern end of the cutting, they 1
= * | conjoin and are crowded with a

$s branching coral. This is Bed 29 |

= of Moore’s Steven’s-Hill section,

7 \ Longe Sutton 1.2... ao
2 28. Pale-brown and green marly shale . 0
pees.) Limestone: a. geen 0
a | B0e.j, Shale..d'a 0 Rae Mee te ce, 0
B Sly bos SHIIMOGTON Gigs ae eer cook scan saosn gy
) ant Shales. c pee ee hs cee teas cc 0
a eae) + himestone an © ere oo ovate es 48 )
a 34. Marl and limestone .................. 0
A Se. MaiMesbOMee a eis ieee oecncces oat sok ass 0

36. Marland limestone ... 0
37 Penal hard, conchoidal frac- ; 0
WUE HUGE ag! Belay ceasieresncaveuee epee cess
38 Marl and rubbly limestone ......... 0
Limestone, cream-coloured, very
} massive, often giving off a 3- inch 1
bedvat. the bases ve. 62.5. lise aces
AO eartinoot shale 2.......2scccecsss+s05- 0
41. Limestone, cream-coloured ......... 7)
Greenish-yellow marly shale and
4 some limestone fitting into the
inequalities of the underlying bed.
Limestone, massive, cream-coloured,
4 with some veins of calcite : top very -Q
irregular . PERO ee Uhre
AA. ; Pale greenish-yellow | “shaly ae
and some rubbly sandstone......... 0
Limestone, cream-coloured, level top,
most irregular nether surtace, fitting
into the inequalities of the ‘under-
oe bed, with a little shale inter-
Wiemincig BO a eee »
Limestone, very massive, some
veins of calcite, most Treglia fg
surface, apparently waterworm ...
Greenish-yellow marly shale: ......
Limestone, hard, cream-coloured, 4
with pyrite... 0
Thin impure ‘Jimestone-layers any
marly shale, pale yellowish-green . § 0
* So

ne
a9

Limestone, massive, vather irre-
gular, y ellow and grey-brown

commpmantiy Clay? -...235.0 22.0 hee 0

aie u [Stratigraphical position of the
Cotham Marpble.|
g. Shales, dark-grey and green,marly. 2
imestone, fine-grained, light-grey
3. ie with darker streaks of more cry vs fo
talline rock ....
oF Shales, yellowish and ‘greenish- -orey

with thin limestone-layers often
ronigmes to form a single massive

(1)

ieeesbnes hard, yellowish-grey :
ACE AE Et eee Bs Pat ete ena
Thin yellowish arenaceous lime-
stone, mixed with sore marl, and
having at the base a very pyritic
ACAD ct ais a ale RR Nene teh ie Re

4 (2) 0
UU

3)

[(Cuartton MacKRELLt. | Thickness in feet inches.

Thecosmilia (?) michelini
Terg. & Piette, and Ostrea
liassica, abundant.

4

Nuculana (?), Plagiostoma

A * %
valoniense (Defrance), Ostrea
liassica.

— sp. (internal cast).

Volsella minima and varieties.
{ Volsella minima, Syncyclo-

nema sp.

Cardinia sp. (int. cast), Myo-

concha (2) sp., Gervillia pre-

qo

| Pleurotomaria (very depressed

6 \. form).
Plagiostoma valoniense, Vol-
8 sella minima, Pholadomya (of
Ph.-glabra group °).
8
1
2
ES
1
11
4
25
18)
1
2
25

51 Protocardia.

20 8

9 Fish-scales.

+4 cursor Qu., Pseudomelania (2),

LOWER RHATIC.
WeEstTBuURY BEDs.

[CHARLTON MACKRELL. |

KEUPER. a

42

IS,

MR. L. RICHARDSON ON THE RHATIC OF

[ Below the pyritic bed occurs in some places |
hard, blackish, crystalline, shelly limestone
(with a layer of ‘ beef’) 5 inches thick ; in
others, greenish-looking mar] in lenticular
masses. In yet other places, immediately
below the pyritic bed are the black shales |
of the Lilstock Beds, containing at the \
very top huge masses of very hard black |
and grey crystalline limestone, sometimes
as much as 2 feet thick, and containing
(though rarely) Chlamys valoniensis,
Isocyprina ewaldi, Cardinia concinna
Sow., aff. regularis Terg. , Vaughan, Gyro- |
lepis alberti Ag., and fish-vertebre. | J

Shales, black, thinly laminated,
(1) | with one or two ver y thin thin tayes
of pyritous grit ..

black, earthy, mixed

fo)

(2) Cy eae
with shale, slightly arenaceous .

0

L@) Shale, black, and

similar lime-
stone

talline, very shelly v

Shale, black, with some earthy

5b. ee hard, dark grey, pees =
0m limestone KE .
Limestone, black, “earthy, “with a
vA layer of ‘beef ” on the “i
surface...
8. Shales, black, thinly Jaminated
Limestone, massive, grey, calcite
9 and selenite present, septariform : :
4.to 10 inches _......
0 Shales, black, thinly ‘laminated :
about ....... ‘
Black and orey ‘indurated, arena-
ceous, micaceous shale sci
into hard black shale ...............
Shale, black .
Deposit similar to 13 but more per- }
sistent, not passing into black shale
Hard sreenish and black arena-
ceous shale ..........
Hard greenish, sandy, micaceous
limestone
Black shale-parting

.
(the grey siliceous
]
o

sandstone.
The poe Bone-Bed. 4 to a 0
imches ..-9
Shales, black, non- n-laminated, ae
ish zone near the organic remains
Limestone-nodules, hard, grey ish,
17. somewhat cr ystalline : to a
18 inches ......
: Shales, black, imperfectly laminated
Indur. ated, er eenish-str eaked, black,
sandy shale, crowded with fish- |
remains and small quartz-pebbles .
Shales, black, non - laminated,
streaked with irregular ‘wnt
sandstone-layers
Grey, indurated, sandy sania
passing up into the overlying bed

0
3
0

1

0

Non-sequence.

Tea-green Marls.’ Pale

yellowish-green rocky mars.

[Feb. 1911,

Thickness in feet inches.

[Compare Sparkford-Hill section,
p. 48, and St. Audrie’s Slip,
pp. 22 & 26.]

(At the very top the following
| were abundant; Chlamys va-
| loniensis (Detrance), Pteria
~ contorta (Portlock), Placuno-
psis alpina Winkler, Isocyp-
| vyina ewaldi (Born.), and Car-
_ dium cloacinum Quenstedt.
Chlamys valoniensis, Placun-
opsis alpina, and Volsella
(2) minuta (Goldfuss), scales
and teeth (?) of Gyrolepis.
4 Same fossils as in 5a (1).
( Volsella sodburiensis (Vaugh.),
| Pteria contorta, Cardium
_) cloacinum, Isocyprina ewaldi,
22 Placunopsis alpina, Proto-
| cardia rhetica (Merian), scales
L of Gyrolepis alberti Ag.

{same fossils as in Bed 5 5b.

3

0

7 Shelly.

0)

eee coprolites and fish-

remains.

OL

6

13

5

0+ va
Acrodus minimus Ag., Gyro-

6 lepis alberti, Lepidotus ?
(teeth), saurian tooth, copro-
lites, small quartz-pebbles.

7x Pteria contorta common.

15
4
3 lLignite abundant.
6
Full of fish-remains—Acrodus
4 minimus, Gyrolepis alberti,

Lepidotus ? (teeth), and small
quartz-pebbles.

22 4

Vol. 67. WEST, MID, AND EAST SOMERSET. 43
9 5)

The bottom-beds of the Lower Lias that were seen, corresponded
precisely with the similarly-numbered deposits exposed in the
cutting on the west-north-west—that through which the line
passes immediately before crossing the Cary River.

The Langport Beds were exposed in their entirety, measuring
20 feet 8 inches. A bed crowded with the branching coral Theco-
smilia, and comparable with that noticed by Moore at Long Sutton
many years ago, constituted a notable horizon. Here the Langport
Beds fall naturally into five groups—the massive ‘Sizes’ at the base,
and the more rubbly beds near the top. Even in this fine develop-
ment there is oft-recurring evidence of slow formation afforded by
the waterworn and channelled surfaces of the massive ‘ Sizes,’ and
by the manner in which the specimens of Dimyodon itus-striatus
adhere to the upper surface of the lmestones and encrust the
pebbles in the intervening marly layers.

The Cotham Marble was not detected, but its stratigraphical
position was obvious, and it was discovered at that horizon in the
cutting near the Cary River (see p. 45).

Between the Cotham and the Lilstock Beds occur locally
huge masses of hard limestone coated with shell-débris. Similar
masses occur at Sparkford Hill on this horizon, and emphasize
the temporary discontinuance of sequential deposition—of which
evidence was also afforded at St. Audrie’s Slip near Watchet.

Bed 9 was a readily-recognized and conspicuous stratum, for its
large septariform nodules were scattered over the floor of the
cutting at the foot of the bank, down which they had rolled.

The Bone-Bed (15) at Charlton Mackrell is a hard grey siliceous
sandstone, intermediate as regards texture between the Bone-Bed
of the Blue-Anchor foreshore and that at Lilstock. Streaks of
impure, grey, micaceous limestone traverse the bed; but in such
vertebrate-remains are few, being most abundant in the sandstone-
portion.

The basal Bone-Bed (20, lower part) is a grey indurated sandy
mudstone, with flakes of marl which impart to it a laminated
_ appearance.

Cary-Bridge cutting.—Continuing along the railway in the
direction of Somerton, a cutting through a highly-faulted outlier
of Rhetic and Liassic rocks is traversed before reaching the
viaduct over the Cary.

Entering the north-eastern end of this cutting, we perceive
first of all traces of the red marls, with the Pteria-contorta Shales
faulted against them. Then succeed prominent limestones about
the horizon of stratum 3 of the Cotham Beds, followed by bluish
shales as at Charlton Mackrell. Above is the whole of the Lang-
port Beds with the prominent Thecosmilia Bed about their middle,

1 Q. J. G. S. vol. xvii (1861) pp. 491-92.

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Vol. 67.| | THE RHHTIC OF WEST, MID, AND EAST SOMERSEL. 45

and the Sun-Bed—more massive than at Charlton—at the top.
Then come the following Lower Liassic deposits :—

Section IN CaRy-BRipDGE RAILWAyY-CUTTING.
Thickness in feet inches.

(14, Limestone, massive, blue, separating into several beds: seen... 1 2
iis. (shale; palesnrangmrane Srey, © ....5 202... <dsieuacesracadedoavevcen-ascceeos vf
Pi) Arie SLO MEME ee rer 3. sen'n nceng one aacieeuaecics sein ddeeecaed seine budeond 0 43
oo), ALR TEVGR |) (20001 |) 2c one ae ee ee co ee 0 2
<i | 10. lLimestones, bluish: three beds with shale-partings ............ 1 9
ea o> Shale, sreysamdgpale- brown 022. «05.5 0 .sc-a soe sd y.adsyencbesteest 0 9
ne 8. lamestonesmeastes plae-hearted: .....:2i.cscs.sccetsnessasenPaceee nO 7
Fa | 7. “limestone, thim-bedded;/shaly’...../..0.......ceccegeisd. foeec sede ose 1 5
= | 6. Limestone, fissile, massive, bluish-grey . 6 a arte pitt O 8
© | 5. Shale, blue- -grey, passing up into the hed‘above 0 8
| 4. Limestone, brown and blue-hearted .................c.ce ccc ecc eee eee ) 3
| 3. Shale, blue-grey, TEE lea 0128 000) 8 fe a a A Ge aR 0) 1
L 2. Limestone, emitting a fetid odour when struck .................. 0) 3
AO cplaete mPa cs Se eee 5, P ccd teWs co mare Wome eel 5

Langport Beds. Sun-Bed.

Bed 14 is the ‘ Blue Clog ’—No. 14 of the Windmill-Hill section
at Butleigh (p. 38). Thence upwards to Bed 31 the sequence is
the same as that which is exposed at Windmill Hill, with the
differences in thickness noted in square brackets in the Windmill-
Hill record.

In the Cary-Bridge cutting these Lower Liassic beds are affected
by a slight overthrust-fault, and are placed in juxtaposition with the
Cotham and Langport Beds. Here the Cotham Marble (4 inches)
was discovered tn situ, and it exhibited that incipiently-conglomeratic
facies which has earned for it the name of ‘ false Cotham’.*

(B) The Sparkford Hill Area,

(i) Introduction.—North of Qneen’s Camel, near Sparkford, is
a stretch of elevated ground bearing the names of Sparkford Hill
and Camel Hill. From the general geology it is obvious that this
inlier owes its genesis to anticlinal folding and subsequent faulting :
the anticline being doubtless a continuation of that to which
I referred when dealing with Blue Anchor Point and the Polden
Hills.

The inlier is cut through by the Great Western Railway, and
when the line was made a very fine section was exposed.

(ii) Stratigraphical Details.

Sparkford Hill railway-cutting.—This fine section is
now, however, mostly overgrown ; fortunately, it was described in

1 For the guidance of future observers, it may be as well to state that, when
the banks of the deep cuttings on this line had been smoothed down, red sandy
material was frequently spread over the sides. From a distance, this led one
to think that the cutting was wholly in the red marls, instead of ina variety
of deposits (Rhzetic or Liassic, or both).

OstrEA &
SauRIAN BEDs.

46 MR. L. RICHARDSON ON THE RHA&TIC OF [Feb. 1911,

detail by Charles Moore,’ of whose record an abbreviated edition
appears in the Geological Survey Memoir on ‘ The Lias of England
& Wales (Yorkshire excepted)’.’

The section (fig. 2, p. 44) will give some idea of all that can be
seen in the way of beds in the eastern side of the cutting. The
Grey and Tea-green Marls are not well exposed now; but the band
of * white gypsum, erroneously identified by Moore as ‘strontian,’
can be made out, as well as the ‘thinly laminated grey marl’
of his record.

It will perhaps be best to give here a statement of the beds that
are present in the inlier. Details of the Keuper marls and of the
Rhaetic beds, up to the topmost deposits of the Cotham Beds, were
derived from the cutting: the lowermost strata of the Langport
Beds are not exposed; but the remaining beds are excellently seen
in the large Camel-Hill Quarry (No. 3 on the map, fig. 3, p. 44).

Sequence of Deposits in the Sparkford Inlier.

CAMEL-HILL QUARRY.

Thickness in feet inches.

(122 |) 42 | ‘Sandrock ’ Limestone, breaking up
into peculiar oblong pieces

cm)
(Jt)
tH

‘ PLANORBIS ZONE.’
SS

121 | 41 | Clay, blue and yellowish............... orl 0)
ae 40 eee oo averse Re a ee 0 7 Caloceras ‘ohnstoni (Sow.).
119 | 39 naley datos sinches ware. epee eee 0 3 . .
118 | 38 |‘Sandrock’: 2 to 6 inches ............. 0 as ee ees. es Ose
117 | 37 | Shale: AVETABE o.oo coe cbe ees eens cscs 0 2 TEES e Oe ame
116 | 36 |‘ Sandrock’: 0 to 6 inches... aed ewe) 3
115 | 35 | Shale: average . 0 4
| 114 | 34 |‘Sandrock.,’ Bluish, fissile, having
peculiar tubular per forations filled
with iron-oxide; 2 to 8 inches ... 0 2
| 113 | 338 | Shale ...... Ae NSO 2 Psiloceras planorbis (Sow.).
112 | 32 | ‘Slippery Bed’ Limestone .. AO 8 pas se ;
. johnstoni, Ps. planorbis,
hn Bi | Shales, yellowish)... eee muOn) ieee Héssick: A
NOT S0\| BSandrocke: ees ee hearers if 0 Psiloceras planorbis, etc.
109.) 29\\Shale: javerage occ. ees ee eee 5
108 | 28 | Sandrock”: Oto 4 inches).-.2-.)--.4 0 2 Radula pectinoides (Sow.).
107, -275))Shale; hard 74) /.072 455 £5. ee 0) 5 Hemipedina radioles, etc.
HOG 226 Ao Sanadrock? &2..Gotee ee ee ee 8 Very fossiliferous.
bitO5 1 #25 ol'Shale® averages. su:..0:0es.. cere 0) 4,
104 | 2A4Sandrock (2 ee eee @) 4,
103 23 Shale, bluish .. eis 0 6 Volsella minima (Sow.).
| re ce Eight beds a ene d ” (ime
4 A ie | stones) with shale-partings.. 4, 4, Few fossils.
: 93"| 15. Shale® average. 25.\cccsccotees eee il
k O2i SIAN Tamlestone: 2. 2:o2. 3 shes eee ete eee 0 Ostrea liassica abundant.

1 Q. J. G.S8. vol. xxiii (1867) pp. 461--64.
2 « Jurassic Rocks of Britain’ vol. iii (1893) pp. 77-79.

INSECT AND
CRUSTACEAN BeEps.

[(CamEt-Hitt Quarry. |

Laneport Bups.

Cornam Bumps.

Wol. 67.]

( 91 | 18
90 | 12

| 89 | 11

88 | 10

87

86

85

EAS

(0.2)
(st)
RPbw ek OO~10 6

Pl
P2
33 | 3

OO ES ean ee
Sra

(su)

ou

31
30 | 4

| 29( pars)

WEST, MID, AND BAST SOMERSET. 47

Mari

‘Insect-Limestone.” Cap’: average @)

Shales OMor2nmchess sis). seo ee se

| ‘Hat and Cap’ Limestone: 4 to 8 ins.

Shale: O/forgmmehes © fy. ek bo sss
Limestone: 2 to 6 inches ............
Shale -aueraere yee tc. sc nceemereee
‘Insect- Limestone’ aa age TAD ee
Shales hardeerrers ees. 5. «cde vosces coos:
“Tnsectalinmestome?)....d2 5: - <6. 2. ees.
Shale sae eee ee eats

5 Pore Shales

{Si = beduauimestone.....:.....-...
Mia lav ena eens soens ss cn.cses woeseeos
‘Block-Bed’ Limestone............
Limestone .. Bb Ses OE
HaTAATES HOMO M ee atoees tose ea eese betes ne
SITES Cons cee oe Sn

OLDEN IG. onan ssc gas ee es

OAM SONNE He secede vey eclea soeccneeeadice

Shales .2.555 Baye

Limestone, rubbly, and marl .........

Waimestonest ay a,

Shale .

Limestone; has a yellower ap-
pearance than the other beds

SS TRGN Oca coke es cle ae een ee eee

Limestone ..

Shale . ea kes Meier

Limestone : average

Shale .

ee with a partings......
WR TNMN ESOC e. fee ac teak vcice hehe eeacen
Shale ......

Limestones, more rubbly

Shale and pebbles................:.
Limestone, massive. aie
Limestone often in two beds ... Hoga
MimMrestONe = SCCM ccc eon eee

Thickness in feet inches.

Ree tion ok Watches Beds.]

(9) 2
4,
0) 2
0 6
(0) 2
8) 4
0 2 LEryon.
0 6
O 2 Eryonwilmcotensis Woodw.
0) 6
0 3
(0) 6 Insect-remains.
(0) 4,
1 4.
0) 1
il 2
0 75
iL 0)
0 Os
0 2
8) 0%
0 2
8) 13
1 A,
2 1
0) 2
(0) 4,
0) 3
(0) 25
0) 2
0 8
(0) 1
2 5
0 3f
6) 1
3 0 ; Plagiostoma valoniense
(Defrance), ostracoda.
0) 5
OMY Aud
il 4
8) 3

[Not exposed in the quarry, but tabulated on Moore’s

authority. ]

Limestone; remainder ... 0) 3

N12 CEs ena pean rer er st oa ) it

IMNeStOnes 2334, ee eae ea (0) 6

DmbestonG<uus ort Nig star sehen seat ties 0 is

iimestonea geass oe ee et 5
20 8

SECTION IN SPARKFORD-H1LL RaitLway-Curtine.
? Position of Cotham Marble.

Marl (teste Moore)
Limestone, pale, fissile............
Limestone, greenish, concre-
GOMOD prema ece ee kc
(1) Marls, pale green, shaly av..
(2) Limestone ....... #
; Limestone ard shale..........
Marl, brownish-yellow ......

2 LO

0)

oOoone

7

0
9
9
6
2

Fish-scales.

14 11

RR ESS ERS

48 MR. L. RICHARDSON ON THE RH TIC OF [Feb. 1911,

[SpaRKFORD Hitt. ] Thickness in feet inches.
[ Here comes apparently the line of hard

greyish - green crystalline limestone-

masses, of which one boulder-like mass

is seen projecting through the turf. |

2p a EN

2 29 (pars) Shales, black, laminated: avy. 1
a to 5a ! Belles of thin limestones and ;
17 shales ..... 1 63 B
a 16 56; Limestone, with ‘beef’ below 0 35 Ueue fossils of ne
a 15 6 Shale, black ECE ON oatiee as <3 () 2 eria-contorta Beds.
| 14 7 | Timestons a ene O68 |
28 ie 139/96 col) Shales i 5,.ee.rc.ceaer ee ee 74 ae a)
S 121 dM Sandstone (im saa wanetanntc cs 2 0 Gyrolepis alberti Ag.
11 12) Marly deposit, -oyc94--0000-. O 5
10 13° | (Sandstone). ose se ae 0
9 14: Marly deposit: 77.700... ) 8 ( Acrodus minimus Ag., G.
le ee 15). | “Sandstone ya ny oe eta 6 } alberti (scales and teeth),
Isocyprina sp. indet., etc.
[Position of Sully Beds.] ge!
Marls, greyish, with a few oe of
Keupnr. § gypsum: seen (feste Moore) ............ 80 6

No additional information with regard to the Westbury and Cotham
Beds supplementing that given in the above record is necessary.

Camel-Hill Quarry (3) exhibits the sequence of deposits from
Bed 40 to 122 of Moore. Moore’s numbers were applied to the.
beds that he saw in the railway-cutting, so it will be understood
how persistent are the individual layers in this inlier.

There is no need for a detailed notice of this section at Camel
Hill: all the stratigraphical information that can be required is
given in the record on pp. 46-47 ; but it may be as well to empha-
size the point that the local Insect and Crustacean Beds are very
distinctive deposits, and occupy a position in this neighbourhood
inferior to the Saurian and Ostrea Beds.

In the quarry distinguished as 4 on the map (fig. 3), the highest
bed seen is Bed 84 of Moore and the lowest his Bed 71. The Sun-
Bed is a ‘ragged’ rock with longitudinal borings, and is overlain by
clay, the bottom layer of which is of a conspicuous chocolate colour.

In Quarry No. 5, the white limestones of the Langport Beds are
‘seen at the base, and then above them come beds corresponding to
those numbered 79 to 92 (according to Moore’s notation) of the
Camel-Hill section.

In Quarry No. 2, the yellow bed (65) is at the top, and below
a succession similar to that at Camel-Hill Quarry can be made out.

In the wood close to the railway-cutting is the Sparkford-Hill
Quarry. The Langport Beds are very fossiliferous at certain
horizons, and have yielded Pseudopedina tomesi(Wr.), Cardinia sp.,
Plagiostoma valoniense (Defr.), Dimyodon intus-striatus (Emmerich),
Grammatodon lycetti (Moore), ostracods, etc. The lowest beds visible
are the massive limestones in the neighbourhood of Beds 41 to 43.
By following up the section, the same horizons and deposits as at
‘Camel Hill can be distinguished, and the massive-looking stratum

1 Beds 11 to 15 (or 8 to 12 of Moore) are seen cropping out in the side of the

track near Camel-Hill Quarry (see map, fig. 5); there however, Bed 13 is nota
sandstone, but a fossiliferous limestone like Moore’s ‘ Flinty Bed’ of Crocombe.

UPPER RHATIC.

eae eae ee cf

-——-

Vol. 67.] WEST, MID, AND EAST SOMERSET. 49

near the top is the 25-inch bed which comes above the ‘ yellow-bed
horizon’ (65). Following the excavation in the direction of the dip,
we come upon the Insect and Crustacean Beds, then the Saurian
Beds and all the deposits up to Bed 122, which, as at Camel-Hill
Quarry, breaks up into peculiar little oblong pieces.

(C) The Somerton-Langport Area.

(i) Introduction.—The principal section in the area is in the
railway-cutting south-west of the Union at Langport, and will be
considered first. It has been very briefly noticed by Mr. H. B.
Woodward.’

Gi) Stratigraphical Details.

Langport railway-cutting.—In the approach to Langport
Station greenish marls with pinkish zones, reminiscent of the Laver-
nock section, near Cardiff, are exposed.

From the Station to half-way between the first and second bridges
similar greenish marls, but with harder white zones, are exposed.
At the first bridge these are capped with gravel, composed mainly
of well-rolled fragments of the white limestones of the Langport
Beds ; while south of the second bridge is the following section :—

Rartnway-Curtine Section, LANGPoRT.
Thickness in feet inches.

Heslerelnmmestone, WHILE f...5 oes. dots be tee geeee ee cece — Ostrea liassica Strick].
oo: Marl] . Dts Siena Ase ae Re 0) 2
33. Limestone, te eet eos Me 0
| 34, Marl . LANA a TANASE Rn oa ya d # VC) 3 ;
30. Limestone, HIS ee ener Me ner eee ls jae eg lycettt
36. Marl Rae Seats On 5 mee
37. Limestone, white .. 0 5
cig ie Marl and limestone, with a 2. inch layer of
B | 38 1 Glayome tenho: (dence caries: otetsneecaae! ; ?
- | 39. Limestone, white, in two layers 0) ri
EAs Marl indurated: im places ....2...04.:5c.....'0 of coos
By All. Pere eee te trek ck 0 4i ee Qu.,
eae Weanl anderpbple: hy sain a worse ceux O 2 AO EG aa
A Apes Me ShOMes WME ese) kB 2g stie sss es 0 4 \ Zor 2 ne ean US
4 | 44. Marland mubple teak 0 35 SOR saree
45. Limestone, massive, white.. aes OVE! “ProtocardaQnternal cast).
Meartend rubble <.cicch-c nO 3
46. Limestone, massive, white.. fi 2 Crypts of Lithophagus.
47. Marl . ee ews OR re ne) 2
48. Limestone, rubbly Be Se a AA) 4, Ostrea liassica.
AD; (Markee... . 0 25
(50. Limestone, grey ‘ish- white, ‘rubbly .. 0 8
Seen 8 3
(fs Shale, bluish-grey & brown, clayey. 0 2
1. Cotham Marble. 0 2
: 9. Vee with thin layers . 9 5 Grnriecdaret the top.
Fa | 3. ae Picea hard, pluish-grey : “4, to 8 ho 6
a. ts (ae bluish-grey and pale yellow, Oat
iS indurated in places...
Q\y4 Limestone, hard, bluish-grey_ and
S14) 2 (2)< yellowish, with a layer of ‘beef’ +0
immediately below it..
e L (83) Marl, pale ereenish-grey, sandy .. MED 0 5
a OU
1 + Summary of Progress for 1904’ Mem. Geol. Surv. 1905, pp. 163-68.
O73. GS. No. 265. | E

50 MR. L. RICHARDSON ON THE RH ATIC OF (Heb: zomg

ee ] Thickness in feet inches.
Shales, black and grey, laminated
with brown layers, one being parti- : a:
sod cularly noticeable about the centre: 2 5. Candiumelowemuat Gis
26 to 32 inches ......
A peculiar black and. ‘ferruzinous
5b. } deposit, which fills in fissures in te 0) 1
| bed below! .
Yellow rubble and brown. earthy
| 6. TAEDA! Soe ce . 2
: Limestone, hard, grey, rather sandy, Chlamys valoniensis (De-
oS | a 7. breaking up into three layers, with 4 france), Pteria contorta
| 8 ‘beef’ above and below. Baryto- (Portlock), Protocardiw
Ss | a] celestine and pyrite: 2 to 6 inches. ( rhetica (Merian).
= Be | Fy eae black, ferruginous about = Healer
< S| Cenbremes
c2 Limestone, dark, earthy, nodular, and ae ,
eS a 9. | where present very conspicuous, sot 0) 9 a es ee ee
= = occasionally passing into rubble . Midst ae COC ES
Shales, black and grey, well-lami- 3
= | 10 to 12. 1 nated, with a few gritty seams a 10 0 Pteria contorta, etc.
13. Sandstone, greenish-yellow, earthy . 0 3 Fish-remains (scales).
| 14. Shale, black and yellow, clayey ...... 0 if Capes Tepe OK
15 ee Blanes 0 3 a he ree ‘3 ll z ie
calcareous: 1 to 6 inches ...... = enbl pik Peers Noe
| 16 to 18. Shales, black .. 2 3 bee
19. Sandstone wwhitish-yellow, micaceous 0 O03 Fish-remains.
| Shale, black, laminated ..... 0 9
20 | eis. black, indurated, and. ee 0 OL ;
(eae marl .. 2 Fish-remains.
BU areas tae 23 0

KEUPER. ce and Tea-green Marls. Marls, pale? 1 a

yellowish-green; seen

There is nothing to remark concerning this section that is not

sufficiently bruught out in the above record. Bed 9 was very
conspicuous, and, as usual, the individual deposits of the Cotham
Beds could be readily identified.

Escarpment between Somerton and Wagg.—In this
escarpment there are no exposures worthy of note; the only
discovery of interest was that of typical Cotham Marble, cropping
out of the bed of the rough road that climbs the hillside through

Somerton Wood.

Ham Hill inlier.—The Geological Survey map represents an
extensive spread of Rhetic beds to the north of Langport; but
several quarries now show that the representation of the superficial
extent of the Rhetic has been too hberal. In a quarry about a
quarter of a mile south of Turn Hill, Lower Liassic beds similar to.
their equivalents at Butleigh (p. 38) were exposed: the lowest

bed visible being locally called the ‘ Clog Stone,’ and comparable

with Bed 14 of Windmill-Hill Quarry. Near the old windmill
between High and Low Ham the ‘ Sizes’ of the Langport Beds are
exposed; and formerly the Black Shales of the Westbury Beds.
could be seen above the fine exposure of the Keuper deposits at.
Turn Hill.’

1 There may be a slight break here.
2 W. Boyd Dawkins, Q.J.G, 8. vol. xx (1864) p. 404.

Vol. 67.] WEST, MID, AND EAST SOMERSET, 51

(D) The Langport-Howley Area.

This area is represented in Sheets xviii (old series) & 311 (new
series) of the Geological Survey map.

With the exception of the neighbourhood of Hatch Beauchamp,
where the beds are affected by a fault, the uppermost deposits of
the Keuper and the lower strata of the Rheetic crop out in a bold
bank that is continuous from Langport to Pickeridge Hill. Thence
south-eastwards for a space of about 5 miles the outcrop of the
Rheetie is concealed under the Cretaceous rocks; but the Pteria-
contorta Shales are seen again near Knapp Farm, in the deeply-
excavated Yarty Valiey.’

In the escarpment between Langport and Pickeridge Hill there
are but few sections of the beds under consideration now open.

In the side of the track leading down the hill to Wick, the
following details may be observed: at the top rubbly cream-coloured
beds, belonging to the Langport Beds; a band of hard limestone
[4(2) of the Cotham Beds], which rests upon a greenish marly
shale [4 (3)], and this in turn upon the Black Shales. The hard
limestone in these is Bed 56. At Red Hill, the Red and Tea-green
Marls of the Keuper are finely displayed; but the most interesting
feature in this neighbourhood is the bored Sun-Bed.? Similar
phenomena are to be observed at Breach Hill in Hast Somerset, and
indicate a non-sequence. Near the Parkfield Monument and close
to the main road, is a quarry in the Lower Lias opened up in
beds equivalent to those numbered 30 to 38 (in my notation) at
Butleigh and Camel Hill (pp. 38 & 46 respectively).

Between the Parkfield Monument and Fivehead there are no
sections to record; but at the iatter place—close to the main road—
is a quarry in which the section represented in the appended diagram
(fig. 4, p. 52) can be made out. It was interesting to find so
unmistakable a representative of the Cotham Marble, here as at
Dundon (p. 39) associated with some very dark sticky clay.

At Crimson Hill, near Hatch Beauchamp, the escarpment is
pierced by the tunnel that allowed passage for the now almost
wholly destroyed Bridgwater Canal. It was from pieces of rock
that had been brought out of this tunnel and tipped near the
quarries at Beer Crocombe, that Moore obtained the extraordinary
suite of fossils that he described as having come from the ‘ Flinty
Bed’ of Beer Crocombe.* He was at first puzzled as to the
precise stratigraphical horizon of this ‘ Flinty Bed’; so was the
Rev. P. B. Bfodie, who sent a selection of specimens to Wright: the
latter could only suggest that it might be equivalent to the ‘ Cypris-
Bed,’ or Estheria Bed as it is now called, of such Gloucestershire
sections as that at Garden Cliff.* However, Moore came to the
conclusion that the bed occurred in the ‘ Avicula-contorta Zone’? ;
and, although it has been suggested that all his specimens may

1 Proce. Geol. Assoc. vol. xix (1906) p. 409.
2 See Vert. Sect. Sheet 47, No.5 [Curry Rivell] Geol. Surv. 1873; and
H. B. Woodward & J. H. Blake, Geol. Mag. vol. ix (1872) p. 197.
3 Q.J.G.S. vol. xvii (1861) p. 486.
4 Ibid. vol. xvi (1860) p. 384. 5 Ibid. vol. xvii (1861) p. 486.
E2

o2 MR. L. RICHARDSON ON THE RHEHTIC OF —*([F eb. 1911,

not have come from one horizon,” I am satisfied (after an examina-
tion of the specimens in the Bath Museum) that all so labelled did
come from one horizon, and feel little doubt that that horizon is
Bed 13 or the Pleurophorus Bed of West Somerset.

Fig. 4.

Diagrammatic Section of the Quarry at Fivehead.

Langport

Lower Beds
bios Langport
& Beds
Langport
a Cotham Marble <_<
/ Ze
Beds moe

Cotham Beds

The section in the railway-cutting between Hatch Beauchamp
Station and the tunnel was originally investigated by Moore,” and
later by Mr. H. B. Woodward.* The Westbury Beds are 22 feet
2 inches thick, and at 11 feet 10 inches above their base occurs the
stratum that Moore identified with his ‘ Flinty Bed.’ As has been
remarked, it is unfortunate that he did not record any specimens
therefrom.* The Cotham Beds are thus constituted here :—

Thickness in feet inches.
[1. Position of the Cotham Marble.]

2: Vag bteblie marl oo se. est canoes eee ecko s nae see 3 0
3. Grey stone with darker layers ..0as.-escsectess a eo. 1 2
AruGrey marl ian Stome 2.200 isan, see eee ees ake scree 0 7

In the Geological Survey Memoir on the district, in which an
abbreviated edition of Moore’s record is published along with an
excellent sketch-section, Mr. Woodward remarks (p. 26) that
‘it may be questioned whether the “ grey stone with layers of darker colour ”
and overlying “light blue marl” should not be placed with the White Lias.’

I think, however, that the interpretation given above is correct.
The Langport Beds are only 9 feet 4 inches thick here, according
to Moore, so they have decreased considerably in thickness.

About half-way between Stoke St. Mary and West Hatch is a large
quarry, in which the uppermost strata of the Langport Beds and the

1 «The Geology of the Country between Wellington & Chard’ Mem. Geol.
Surv. 1906, p. 27.

2 Q. J. G8. vol. xxiii (1867) p. 469.

3 «The Geology of the Country between Wellington & Chard ’ pp. 25-26.
+ Ibid. p. 27.

Vol. 67.] WEST, MID, AND EAST SOMERSET. 53
kottom-beds of the Lower Lias, here called the ‘ Blue Lias,’ are
excellently displayed. Moore measured the section, and to the
extreme accuracy of his record I gladly bear witness.' He
did not observe any exposure of the Pteria-contorta Shales near
Stoke St. Mary; but their junction with the underlying marl may
be seen in the lane east of Stcke Court.

(E) The Wedmore Inlier.

The total thickness of the Rhetic Series in this inlier has not
been ascertained.

The Red Marls are exposed at many points, and at Panborough
have the Tea-green Marls faulted against them. The Tea-green
Marls are also visible at several places, notably in the roadsides at
Bagley ; while between Theal and Bagley, in Snake Lane, Red
Marls, Grey and Tea-green Marls, and the Pterta-contorta Shales,
with their associated hard beds, are exposed.

The Snake-Lane Section is not so clear as it was in the days when
Prof. Boyd Dawkins investigated it?; but, with a little care, the
following succession can be determined :—

SnaKkE-LANE SECTION, NEAR BAGLEY.

Thickness in feet inches.
fi [12] 3 14. ; Shales, black and grey, with reddish
sandy layers: seen . 1 6
(The Bone-Bed. Sandstones, hard,

| pale grey, calcareous, in three to six
[11] 15.4 layers with shale-partings. On the
| weathered surface is much shell-
(_ débris; average ..
[10] 16. eee black and ‘greenish - grey,
= with reddish-brown sandy layers .
[9] 17. { Limestone passing into a sandstone:

StS

(Acrodus minimus Ag.,

Gyrolepis alberti Ag.
(scales and teeth), Iso-

Mytilus sp., gastropoda

| cyprina ewaldi (Born.),

(several species, etc.).

iy
: 4
A
Pa) average 8) 1 Fish-remains.
| [8] 18. Mayl, yellowish, ‘sandy, laminated... 0) 5
2 J [7] 19. ee hard, grey, passing into
P a sandstone of ‘bone-bed’ nature . 0O 1
Et Zi stile, yellowish, sandy” ........-...... -O Os Wein eh care eee ae
a | [6}+21. Sandstone .. ER ee 4 dia ration (Merian)
= 22. Shale, yellowish, sandy ............ Sole eee ean) -
[5] 23 ee full of vertebrate-remains,
S “(passing into a compact limestone. 0 4
| Shales, black: about .... eat var 4
caf i {smuston, soft, reddish- brown ...... ) 2
| Shales, black, clayey : abou6 =. e5 1 0
‘Wedmore Stone.’ Limestone,
| (o| 27 | hard, grey and often blue-centred, Isocyprina spp., small
shelly, massive: 1 to 3 feet ......... 2 2 } gastropoda, and occa-
[2] 28. Shaies, black, clayey: about ......... 4 0 sional fish-remains.
3 Grey and ; Marls and marIstones, whit-
& | Tea-green Marls.* ( ish and greenish-grey ...... 20 7
5< Red marls, with zones of
a Red Marls. } grey and mottled marl:
ark BERN GA Le Red ose oe. HT? oe 20 O

* Q.J.G.S. vol. xvii (1861) p. 490; see also ‘ The Geology of the Country
between Wellington & Chard’ Mem. Geol. Surv. 1906, pp. 26-27.

=) J.G-S: vol. xx (1864) p. 403.

3 These correspond to the numbers of the beds in Prof. Boyd Dawkins’s

section.

4 Additional details of these deposits will be found in Prof. Boyd Dawkins’s

paper.

— 2... = =

ot MR. L, RICHARDSON ON THE RH ATIC OF [Feb. 1911,

The limestone called the ‘ Wedmore Stone’ is prominent, and in
the past has been extensively worked in the neighbourhood of the
country-town whence it derives its name. But now not a single
quarry is open, and even traces of former workings are difficult to
locate.

The stratigraphical position of the Wedmore Stone has been the
subject of discussion. Prof. Boyd Dawkins, in 1864, showed
clearly enough that it occurred in the Pteria-contorta Shales,”
although J. H. Blake was dubious about the matter*; but in 18387
Mr. H. B. Woodward agreed with Prof. Dawkins that it occurred in
the Black Shales.’ Its true position is about 4 feet above the base
of the Pteria-contorta Shales, and about 13 below the horizon of the
bed that I regard as equivalent to the stratum numbered 15 (or
the main Bone-Bed) in other places.’

In the neighbourhood of Sand, the Grey and Tea-green Marls
are succeeded by 4 feet of ‘ greenish calcareous shale full of Avicula
[ Pteria] contorta,’ and this by the Wedmore Stone; but the bulk
of the deposit between the Wedmore Stone and the Bone-Bed
(Bed 15) 1s a soft ferruginous sandstone.°

I have not observed any sections of the Cotham Beds in this
inlier, and there are no details available to show how thick
they are. Mr. W.A. E. Ussher noticed a bed at West Stoughton,
which he thought might represent the Cotham Marble; but, as the
Jew Stone, which is the top-stratum in this district of the Langport
Beds, is also reputed to resemble Cotham Marble ‘in texture
and character [although ] without dendritic markings,’ some care is
required in its identification.

The Langport Beds are occasionally exposed at the bottoms of
quarries in which the principal strata worked belong to the Lower
Lias. The details with regard to the beds about the junction of the
Langport Beds with the Lower Lias were all obtainedin the neigh-
bourhood of the Stoughtons—a group of villages situated north-west
of Wedmore. Four quarries were in work when I visited the neigh-
bourhood for the fourth time, in June 1909. ‘The section in the
quarry near the farm, half-a-mile south-west of Ashton Church, is
described on p. 55.

The local names of the beds were communicated by one of the
quarrymen. In this quarry the Blue-Lias Bed 8 was represented
by fragments of limestone in the soil; but it 1s seen 2 situ ata
quarry in a field, on the right-hand side of the road from Ashton to

1 Q.J.G.S8. vol. xx (1864) pp. 405 ez seqg.

2 «Geology of East Somerset & the Bristol Coal-Fields’ Mem. Geol. Surv.
1876, p. 85.

3 ‘Geology of England & Wales’ 2nd ed. (1887) p. 250.

4 The most satisfactory pieces of Wedmore Stone, from a palzontological
standpoint, that I obtained came from a pond-excavation on the north side of
the road, 3 furlongs due north of Mudgeley Farm.

5 The only exposure now available is in the sides of a pond, in the field by
the roadside opposite Sand Farm.

Lower LrAs.

LANGPORT
BEps

Vol. 67.] WEST, MID, AND EAST SOMERSET. 55

SECTION IN THE QUARRY NEAR ASHTON.

Thickness in feet inches.

(8. Limestone: fragments in soils, but normally 0 8
7. ‘Broad Shale’: hard yellow and blue-grey
paper-shales ...... 2 0

6. ‘Corn Size’ ‘mne- textured, ‘anc: centred
limestone. Will not sialindl the frost;

11 to 14 inches .. OF St Ostrea liassica Strick].
4 5, Cle Rasa peewee cet) CCG 052 Le Beas eee) 11 Ostrea liassica.

(One bed at Stoughton-
| = oe ee erey, ae eee Lae wee ee 2 : ; Cross Quarry, where it
| 2. HA eeGone: locally called ‘The Flat’ ...... 0) 3 aaa and is 5
I Lic (GEE ARMIN, oct ee ae OF

‘Jew Stone’; hard, cope yielding a
conchoidal fracture ........ é pret hss oe 0) i
Clay-parting ..... 0) =
Limestone, compact, “blue inside, locally called
‘The Skud’: 4 to 6 inches ......0.....0...... 0 6
(Cl eres Te an So see tae ey mene Ne Onan on Amr. 0) is
Protocardia, Ostrea (15
Limestone: locally called ‘The Clog’ ......... 0 9 inches thick at Stoughton
Cross).

West Stoughton, with the other beds as exposed at the preceding
quarry below that stratum. In the quarry at Stoughton Cross the
beds are somewhat disturbed; but the sequence is the same as at
Ashton, with the modifications noted in parentheses in the record of
that section.

(F) The Uphill-Shepton-Mallet Area.

This area embraces those numerous disconnected patches of
Rhetic deposits, which are either in actual contact with the
Paleozoic rocks of the Mendip Hills, or occur in outliers removed
at a greater or less distance therefrom.

In proximity to a mass of older rocks, which—on abundant
evidence—formed a land-surface during the time of formation of the
newer rocks, it is not to be wondered at that the Rhetic deposits
are subject to considerable variation in thickness and character.
Some of them are conglomeratic; while sediments of this epoch,
along with vertebrate-remains, have found their way into fissures
in the Carboniferous Limestone, or repose in shallow hollows upon
its much eroded surface. Sometimes, however, where an ‘ abnormal’
development of a Neozoic rock might be expected, there is a
‘normal’ development instead.

The first section to be noticed is near Uphill, not far from
Weston-super-Mare, where the Rhetic Beds are exposed in the
great cutting which here traverses the Mendip Hills.

Railway-cutting, Uphill.—This section has been men-
tioned by several authors. Thomas Wright, Charles Moore, and
Bristow & Etheridge, all of them contributed original observations.
Mr. H. B. Woodward has given a picture of part of the cutting,
showing how highly faulted the beds are; and this feature is still

LOWER RHATIC.

=
e
Ay
=)
ea]
Ne

56 MR. L. RICHARDSON ON THE RHETIC OF (Feb. 1927,

more clearly brought out in the section made by William Sanders,
and reproduced in the Geological Survey Memoir on the district:
published in 1876." |

Wright’s description of the section, published in 1860,? was
closely followed by one drawn up by Moore.’ Wright’s record differs
widely from that given later by Bristow & Etheridge,* so much so
that it is impossible to institute a comparison. These latter do not
record a single fossil, and only give details of the Pteria-contorta
Shales for a distance of 11 feet 9 inches above the top of the marls.
Wright's section is not too easy to understand, but he assigns a
thickness of a little over 25 feet to the ‘ Zone of Avicula contorta.’

Moore’s section, unfortunately, is also of little use, for he gives
no details of the deposits between the Lias and the bed which he
identified with the Bone-Bed. In his collection at Bath, however,
there is a piece of pale yellow limestone, identical as regards lithic
structure with the ‘ Naiadites Beds’ of ‘ Redland (New Clifton),’
Bristol,’ and containing Darwinula liassica (Brodie) and Lycopodites,
which bears the legend ‘ Rhetic Plant-Bed, Uphill.’ So the West-
bury Beds are represented here ; and certain of the layers, at all
events, are quite typical as regards lithic, faunal, and floral
characters respectively.

When I visited the section, by kind permission of the Great
Western Railway Company, I found it very much overgrown; but
near the top of the western bank, between the single-arch bridge
which spans the cutting and Bleadon (or Uphill) Station, I was
able to note the following details :—

RatLtway-CutTtine, UPHILL.

eng ler, Pteria contorta
| | (Portl.), Cardium cloaci-
nara, ly Limestone. Lime- ; 9 0 num Qu., Chlamys valo-
A stone, hard, dark dd SaaS ea niensis (Defr.), Proto-
I | cardia rhetica (Merian),
Isocyprina ewaldi
J Shales black vee): 122.2e-¥e cee eee eres - | (Bornemann).
'S) ae : ae
es (a. Pyritic sandy limestone, Acrodus minimus
5 | with conspicuous green Gyrolepis alberti
i A ;
Patehesy cs tae: cee cee aw 1 Saurichthys acuminatus
= — Bone-Bed. 6. Shale and_ sandstone - Ag., Hyhodus minor Ag.,
| avers turner 0 3 small quartz-pebbles, Iso-
Le. Sandstone, hard, grey ... 0 2 cyprina sp. indet.
Ce 16. Shales, black, laminated; about ......... 3 0)
aa nnnnn~ Non-sequence.
hae Marlstone, hard, yellowish-green ...... 1 0)
ae Marls and marlstones: according to
Marls Bristow & Etheridge, about ......... 37 0
Red Marls.

1 «Geology of East Somerset, &c.’ pl. iii facing p. 24.

2 Q.J.G.8. vol. xvi (1860) pp. 382-84. 3 Ibid. pp. 445-46.
4 Vert. Sect. Geol. Surv. 1873, Sheet 46, No. 3.

5 W. H. Wickes, Proc. Geol. Assoc. vol. xvi (1900) p. 422.

Thickness in feet inches. ( Placunopsis alpina Wink-

Vol. 67.] WEST, MID, AND EAST SOMERSET. 57

It is unfortunate that so little reliable information is available ;
but it was interesting to find Bed 56, which was replete with
specimens of Cardium cloacinum and Placunopsis alpina,

Milton Lane, Wells.—About a mile to the north of Wells is
the section that was described by the Rev. P. B. Brodie in 1866 as
that of ‘ Milton Lane.’* In it Keuper, Rhetic, and Lower Liassic
rocks are exposed, and it is of especial interest in that it shows
the last-named in close proximity to the older rocks of the Mendip
Hills still maintaining their normal lithie characters.

Two faults, unfortunately, affect the rocks: the one throws the
Tea-green Marls against the Red; while the other disturbs the strata
which occupy the stratigraphical position of the Cotham Beds, and
renders exact details difficult to obtain.

Mitton-Lane Section, WELLs.

Thickness in feet inches.

Alternating bands of limestones and shales,

LOWER of planorbis, megastomatos, and mar-
LIAS. moree hemerez. Ostrea Beds and Pleuro-

mya Limestones and Shales.

[Gap, owing to a slight fault.]

r [ ae of the Cotham Marpble.|
‘ ales pale green and yellow; ? about...... 3 0
eee Brown arenaceous deposit ..................... 0 Os 1 ae Gay = Detice oppels
Oa ; aaa Moore, at the top.
HA = Limestone, hard, greenish ..................... 0 4, Wich a ere Get bing
P 5m Limestone, sandy, ferruginous ................ 0 l= 1 Rane Quenst dt
Cld i Limestone, hard, greenish-grey................ 0 4 oN
Sal J SALOME 211: We ae ee ee Eel SNe eae ene Ee 0 1
rR s & Marl, greenish-yellow, often indurated ... 0 9
oe a 0} Sia pe ee ae and more clayey at GE fer con tories
ae to) UNeR base SO. LOO teh a. 9, eee ee eS 6 { Zone fossils.

a a Acrodus minimus Ag.
| ue) | ton Sandstone, yellowish |..... ..2........-4.:..,,0 1 Gyrolepis alberti Ag.,
ome and small quartz-pebbles.

( ae hard, yellow, nodular, with
2 ‘beet’: 0 to 4 inches ieee Meee 10, 4,
(2 6. Marl, soft, indurated in places Este nied eeteaee 4 4,
= & |e. Marlstone, pale greenish-yellow ............ 1 9 From 6 & d@ Mr. H. B.
Raj d Marlstone, soft, whitish: 4 to 8 inches ... 0 6 Woodward records fish-
a oe e. Marl, dark grey, with occasional nodules scales.
aa ST tae at the OD ee tas te eR Re 1 4,
5 | o Jf. Marlstones with median clay-seam ......... 1 1
‘eo g. Marlstone, whitish in dark marl ............ 0 5
ra | eg Pe AN ET 8 5) C0) eRe pte Eo Nee A a ay 1 3
ited’ Marls:: Marls, red)seen 26.05 ete oe eo deve 2 6

(Then comes a sma!]l fault.)

* Q.5.G.8. vol. xxii (1866) pp. 93-95.

oe

58 MR. L. RICHARDSON ON THE RH ZETIC OF [ Feb? 1911,

All the authors who have described this section have noticed a
bone-bed at the base of the Pteria-contorta Shales ; but, while the
type that Brodie saw was an ossiferous breccia,’ and that which
Mr. Woodward discovered a ‘ tough bluish-brown limestone,’ *? that
which I found was a yellow sandstone with few vertebrate-
remains—a less fossiliferous and thinner Bone-Bed than might
have been expected.’

Between the outher on which East Milton is situated and the
main mass of Lias near Shepton Mallet, are outliers of Rhetic and
Liassic rocks (1) north of Birrel Farm, (2) between the Horringtons,
and (3) at Chileot, but I have nothing to add to what has already
been noted.*

In the neighbourhood of Shepton Mallet the principal section is
that exposed in the railway-cutting south-west of the town, on the
line to Wells. Here the Rhetic Beds are fairly well developed,
but northwards they thin out, passing into conglomerate, and are
eventually overlapped by the Lower lias, which, when it comes”
to rest upon the Carboniferous Limestone, passes into a massive
sparry limestone, locally called ‘ Downside Stone.’

Near Downside, this Downside Stone rests directly upon the
Carboniferous Limestone; but, a little farther south, near the
viaduct, and on the east side of the road, Rheetic beds have come
in between the Lias and the well-planed surface of the steeply-
dipping Carboniferous Limestone. This section is the classic one
that was pictured by De la Beche’; but in his time, of course, the
Rhetic had not been recognized as a distinct formation, and he
called these conglomerate-beds here simply the ‘ thin gravel base
to the Lias.’ Charles Moore, however, who was so quick to detect
anything Rhetic, soon discovered that this ‘thin gravel base’
contained vertebrate-remains—such as he knew characterized the
Rhetic, so he correlated this conglomerate with that which he
had noticed near Hapsford Mills.°

This conglomerate at Shepton Mallet is a breccio-conglomerate,
consisting of fragments of rocks derived from the Carboniferous
Limestone Series (including chert) embedded in a dull-grey matrix
in which occur specimens of Pteria contorta, vertebrae of Plesio-
saurus, teeth of Saurichthys, Sargodon, Lepidotus, Acrodus, and
Gyrolepts, scales of Gyrolepis, coprolites, small quartz-pebbles, and
reptilian bones. The same kind of conglomerate is repeatedly met
with in digging graves in the Cemetery, and large picces of bone
are sometimes found embedded in it.

1 Q.J.G.8. vol. xxii (1866) pp. 94-95.
2 Vert. Sect. Geol. Surv. 1873, Sheet 46, No. 14.
3 Proc. Geol. Assoc. vol. xxi (1909) p. 225.
* ‘Geology of Hast Somerset & the Bristol Coal-Fields’ Mem. Geol. Sury.
1876, p. 81.
° Mem. Geol. Surv. vol. i (1846) p. 278.
° Q.J.G.S. vol. xxiii (1867) p. 507.

Vol. 67.] WEST, MID, AND EAST SOMERSET. 59

About a quarter of a mile due west of the Cemetery is
the quarry in the Carboniferous Limestone at Bowlish, in which,
adhering to the more or less vertical faces of rock forming the
fissure-sides, can often be detected a breccia of Rhetic age con-
taining the small vertebrate-remains characteristic of the epoch;
while, resting upon the planed surface of the Carboniferous Lime-
stone (which is here inclined at quite 45°), are the Lower Liassic
strata.

On the north side of the combe, about a furlong and a half —

south-south-west of the above quarry and at the eastern end of
Darshill Mill-pond, an adit was being driven at the time of my visit
in connexion with a water-supply scheme. The Langport Beds or
White Lias proper were full of the ordinary fossils, such as Volsella
minima (Moore), Pleuromya crowcombera auctt., Ostrea liassica
Strickl., etc. The uppermost bed was pierced by peculiar annelid-
like borings. <A few pieces of greyish rock were also found lying
about, which were partly conglomeratic like the bed numbered 3
in the Three-Arch-Bridge Railway-cutting (see p. 60).

The section described by De la Beche as situated ‘on the south
of Croscombe’! I have been unable to find, but a mile and a quarter
due west of Shepton Mallet Church is an old quarry in the Car-
_ boniferous Limestone, on the top of which limestone are traces of
- littoral ‘Tea-green Marl’; while, in the same field, I picked up
pieces of a peculiar granular sandy rock containing unmistakable
Rheetic fish-remains.

Three-Arch-Bridge railway-cutting, Shepton Mallet.
—This, as I have already remarked, is the place where the best
exposure of the Rheetic deposits in the district is available, and the
cutting is situated about a mile to the west of the town.

The line of demarcation between the Keuper and the Rheetic is
sharply defined, and the same remark applies to the upper limit ;
but, as noticed by Moore, the Planorbis Beds are very close down to
the Langport Beds, and

‘on comparing the Liassic beds with the Camel Section, it will be at once
apparent that the lower members [of the Lias] are absent. .. .”?

As detailed records of this section have been given by Moore, also
by H. B. Woodward, W. A. KE. Ussher & J. H. Blake,® it will only
be necessary here to give such details as will permit of its being
clearly compared with other sections.

Mem. Geol. Surv. vol. i (1846) p. 278.
Q. J. G. 8. vol. xxiii (1867) p. 506.
*t. Sect. Geol. Surv. 1873, Sheet 46, No. 15.

wo t -

Vel

60 MR. L. RICHARDSON ON THE RHZ&XTIC OF [Feb. grr,

Section 1n THree-Arcu BripGe Rariway-Curtine.

Thickness in feet inches.
LOWER § Limestones and le seen log
LIAS. 2? about.. ss Sse cane NL
(Chlamys pollux (D’Orb.).

3 is s Limestones with marly part- | Plagiostoma valoniense (De-
(ea ° 8 ings, the whole cream-¢-12 04 france), Volsella minima
H*A ( coloured ...... | (Moore non Sow.), Proto-
[1. Position of the Cotham \ cardia, ete.
S Marble. |
2) 2. Shales, greenish - grey
a : eee 2 to 3 feet Sie 2 8
~ & imestone, pale greenish-
a i $s
5 } grey, with arenaceous- 1 4 Fish-scales.
erie layers : 12 to 20 inches.
& : 3 ( Thin, hard grey layers, ath
many quartz-grains an
; 5 fish - remains ssing
|B] U BAS tases cameo | cums oti ae
=) | glomeratic limestone with coprolites and fish-remains.
eo small pebbles of Carb.
' \. Limestone: 1 to 8 ins.... }
aa | ? 4. Shale, pale-green, marly . O 8
| 4, 8
ic 5a. Shale, darker, marly ...... Omit,
| F EB 5b We ee 0
G: P oi Bian shay Sas re eee Chlamys valoniensis, Pro-
FJ Ba OU Gy ee hae tocardia rhetica (Merian),
S Ee UM Del eaten eee : Pteria contorta (Portl.),
= Shale, black, earthy, wi Ichthyosaurus.
; y, with
15 ; nodules and layers of a¢ O 7§ Gyrolepis alberti Ag., Chla-
highly pyritic limestone . Mies WOVON UE as
ea eA
(as Marls and marlstones, greenish-
ce ees grey, corresponding almost bed 1 3
ea eee for bed with those at Milton
= ; bane: Wells; (ik ee ee
a Bis Red and variegated marls, with
Ms Macias a little celestine and salt- O
* € pseudomorphs: seen ............

It should be noticed that Moore doubtfully identified the bed that
I have numbered 3 with the ‘ Flinty Bed’ of Beer Crocombe.

South-east of the railway-cutting, past Lamberts Hill, then
round the sinuous outcrop of the Rhetic to Kast Compton, and
thence to North Wootton, no sections are available.

The junction of the White Lias proper with the Lower Lias is
seen in an interesting section in the tram-line cutting, south
of Waterlip Quarry and north-east of Doulting. This section I
have described quite recently, and to that description I have
nothing to add.!

Between the main outcrop of the Rhetic west of Shepton Mallet
and the southern end of the Wedmore inlier is broken ground of
very diverse stratal composition. Bold and often quarried knolls,
partly ringed round with Dolomitic Conglomerate, are inliers of

1 Proc. Geol. Assoc. vol. xxi (1909) pp. 216-17.

Nol, 67. | WEST, MID, AND EAST SOMERSET. 61

Carboniferous Limestone ; while hills, varying in size from almost
tumulus-like mounds to markedly-conspicuous hills (such as Twine
Hill), are composed of Keuper and Rheetic, or Keuper, Rheetic, and
Lower Liassic rocks combined.

I have worked over all the outliers in this part, but have found
little to add to the already published notes of others.*

Twine Hill.—The Lower Liassic beds which cap this hill are precisely
similar in appearance to their equivalents at Ashton in the Wedmore
inlier (p. 55), comprising limestones and conspicuous beds of shale, in
part of planorbis hemera. They rest upon the Jew Stone, to which
succeed below the more rubbly and fossiliferous limestones of the main
mass of Langport Beds.

Lancherley Cross.—Scarcely 200 yards along the road from Lancherley
Cross in the direction of Woodford, on the right-hand side, is a small
section which affords evidence of the continuation of the main
Twine-Hill fault, and suggests that that line of displacement is con-
nected with one of those which traverse the Yarley (or Henton)
outlier.

(3) East Somerset (pars).
(A) The Nunney-Elm Area.

(i) Introduction.—This area embraces the romantic and
picturesque neighbourhood of Nunney and Vallis Vale.

The Nunney Valley has been excavated out of the hard Carboni-
ferous Limestone, which generally has Inferior Oolite resting
directly and unconformably upon its well-planed edges. But in
places, between the Oolite and the Carboniferous Limestone, are
deposits which include Rheetic, Lower Lias, Middle Tas, and Upper
Lias. They lie in hollows in the Limestone-surface, or fill in fissures
in that rock. The extraordinarily fossiliferous character of these
deposits suggests that they represent the accumulations which were,
‘so to speak, washed before the advancing waters.

In Rhetic times there were many fissures in the Carboniferous
Limestone of the neighbourhood, and into these fossils of the
epoch were washed. In places, however, they were accumulated
instead in slight depressions of the limestone-floor, were mixed
with angular or rounded fragments, and now appear as con-
glomerates or breccio-conglomerates fast-fixed to the limestone
surfaces.

Farther away from the old sea-margin, where the surface of the
Carboniferous Limestone declines, as at Hapsford Mills in Vallis
Vale, the Rheetic deposits become less attenuated and gradually lose
their conglomeratic facies. About 2 miles to the north-west of
Frome, it is recorded that the Bone-Bed, presenting its normal
characters, was met with

‘at a depth of 310 feet, in a pit at present being sunk by James Oxley, Esq.,
of Frome, to the Lower Series of Coals of the Somersetshire basin.’ 2

1 ‘Geology of East Somerset & the Bristol Coal-Fields’ Mem. Geol. Surv.
1876, pp. 81-82; see also Q. J. G. S. vol. xx (1864) pp. 403-404.
2 Geol. Mag. dec. 2, vol. ii (1875) p. 96.

62 MR. L. RICHARDSON ON THE RHZETIC OF [Feb. tgir,

(ii) Stratigraphical Details.

Marston-Road section.—This section, thus named by
Moore, is still open, and was visited by the Geologists’ Association
in 18901 and again in 1909*; but, in the report of the earlier
excursion, while there are some remarks on the Inferior Oolite,
there are none on the Rheetic.

Charles Moore records that

‘The Rhezetic deposits are represented in the western end of this section by
a friable marl, about 10 inches thick, in which occur teeth of Acrodus, Sargodon,

etc., and vertebree of Lepidotus, whilst in the floor of the quarry Carboniferous
Limestone is seen.’ (Q. J. G.S. vol. xxiii, 1867, p. 482.)

In 1908 a party of the Cotteswold Naturalists’ Field Club visited
this neighbourhood.* The details which I have obtained and
recorded below have been checked by both that Club and the
Geologists’ Association.

Marston-Roap Srction, HoLweELt.

Thickness in feet inches.

( Acanthothyris spinosa

| (Schloth.), Terebratula
(2) globata, auctt., Syn-

4 1 > 2,
INFERIOR OOLITE ee hard, dense,con be 0) ‘cyclanemamuaer

\(Garantiane). glomeratic at the base ... (Phil), Wsoceraae eae
Trigonia sp. idet.,
mrornnnvnnnnn~ Non-sequence. Ostrea sp.

(Limestone, hard, whitish, )
sparry, pebbles of pure

|
white limestone (? Lang- l =e . i 268
Lirias oss Jail) 2) Glue Test | Variable in thickness.
Top portion considerably |
bored by Lithophagi ...... 3)
Ae NI aS equence.
Limestone,somewhat sandy ts
and earthy, with fragments 0 4. Tee 3 Eee Ae:
of Carboniferous Lime - a mee ane oF
ees SEONG: Ses Se ee Full of fragments of
CWentbury 4 Shalo sallow, rity, aed gf Zpieontra Het)
eds). CALCOUS eon ear reer ;
Breccia in intermittent ee gn te
patches, firmly adherent to i Sia
the Carboniferous Lime- (° 2 Well isiekes elas
ASGOME ee nee eres
RY RII ORI OY IL Unconformity. ‘ :
CaRBONIFEROUS ... Carboniferous Limestone, presenting a very irregular surface.

Leaving this quarry, and descending the hill to Holwell, we
notice a quarry on the right just before crossing the brook. This is

* Proc. Geol. Assoc. vol. xi (1890-91) p. elxxiii. The precise position of the
section is where the boundary-line of the Inferior Oolite and Carboniferous

Limestone is shown on the Geological Survey map, and immediately below the
‘o’ in Holwell.

2 Ibid. vol. xxi (1909) p. 220.
° Proc. Cotteswold Nat. F. C. vol. xvi (1909) pp. 224-25.
* Q. J. G. S. vol. lxiii (1907) p. 399.

Vol. 67.| WEST, MID, AND EAST SOMERSET. 63

the section to which Moore refers in the paragraph on the ‘ Holwell
Carboniferous Limestone & Liassic Dykes,’ but except the state-
ment that in one of the dykes ‘ may be found occasional nests of
Rhetic remains,’ * there is nothing that claims our attention.

Crossing the brook, and ascending the hill on the Shepton-Mallet
Road, we come upon an extensive disused quarry, on the left or
south side of the road. This is the well-known ‘ Microlestes
Quarry’ of Charles Moore.*

From ‘ dykes’ here Moore obtained an extraordinary number of
vertebrate-remains, which are now housed in the Bath Museum.
Moore intended to devote a special paper to their description, but.
unfortunately it never appeared. His dyke is localized now with
difficulty ; but many vertebrate-remains, similar to those collected
by him, may still be obtained near its site—including the teeth of
the little mammal Microlestes.

On the opposite side of the road to the ‘ Microlestes Quarry’ is.
an interesting one in the Carboniferous Limestone, in which, how-
ever, is a fine ‘ dyke,’ from the sides of which numbers of teeth and
scales of Rheetic fishes may be collected. Also, in a hollow exca-
vated out of the surface of the Limestone is White-Lias limestone.
mixed with pale marl, in which are embedded subangular masses of
chert and extremely well-rolled pieces of Carboniferous Limestone.
covered with specimens of Dimyodon wtus-striatus ( Kmmerich ).

Between Holwell and the neighbourhood of Hapsford Mills I
have not detected any deposit of Rhwtic age between the Carboni-
ferous Limestone and the Inferior Oolite. Near Hapstord Mills,
however, there are some extremely interesting sections which were
noticed by Charles Moore and later by Mr. J. McMurtrie.’

The latter appends a section to his paper, showing the relations
of the beds in the three quarries on the east side of the brook at.
Hapsford Mills. He distinguishes them as A, B, and C,—C being
that nearest to the by-road which gives access to the mills and
valley from the road to Elm. The quarry farthest away from the
by-road is the largest of the three, and according to Mr. MeMurtrie
was the last to be abandoned. Here at the southern end, as this
author states, the Inferior Oolite rests directly upon the Carboni-
ferous Limestone (loc. cat.) ;

‘but as the eye passes along the face of the quarry to the northward, atten-
tion is at once directed to a bed which comes in almost imperceptibly ’

between the Limestone and the Oolite.

‘Tt consists of a fine conglomerate, occasionally brecciated, but more:
frequently containing waterworn pebbles, ind it shuws traces of fish-teeth
and scales.’ (Op. cit. p. 105.)

Masses of the conglomerate above described lie at the foot of the
mural quarry-face. The contained pebbles vary greatly in size,

1 Q.J.G.S. vol. xxiii (1867) p. 485.
2 Ibid. p. 487: see also Proc. Geol. Assoc. vol. xxi (1909) p. 221.
3 Proc. Bath Nat. Hist. & Ant. F. C. vol. v (1885) p. 104.

64 MR. L. RICHARDSON ON THE RHZTIC OF [Feb. 1911,

are well-rolled, and frequently very much bored by a species of
Polydora.’ 3 3

The pebbles are cemented together by a dull-grey matrix, in
which occur specimens of Plagicstoma valoniense (Detr.), Dimyodon
intus-striatus (Emmerich), Pterra contorta (Portl.), Chlamys valo-
niensis (Defr.), Ostrea fimbriata Moore (some of which are bored
by Polydora), Cardium sp., Cardinia sp., Plicatula (2) hettangiensis
Terquem, Pollicupes rheeticus Moore, echinoid radioles, Gyrolepis
albertt Ag., fragments of saurian bones, ete.

It was Charles Moore, however, who described the sections here
in greatest detail; and probably, but for regrettable causes, there
would have been yet more detailed information available.

He gives records of two of the sections at the Hapsford-Mills
end of Vallis Vale. The first and southern one of the two was
measured at, or near, the northern end of what is called by

Mr. McMurtrie Quarry ‘ A.’

SECTION IN VALLIS VALE.

Thickness in feet inches.
Limestone, with basal

INFERIOR conglomerate containing 12 0
Oo.LitTeE. Carboniferous Limestone
corals (derived) : seen ......
Stent peel n~~~~~-~ Non-sequence. Estheria minuta, vay.

(Clay with me aa 1 02 Srodieana Jones, Ly-
| EHINOL IKONS 5550 05> e00cun one copodites lanceoiatus
(Brodie), insects.

Estheria minuta, var.
Conglomerate.................. 0 44 brodieana, Proto-
RHZTIC Clay, blue Meee nesecen | Os “AN Candia
(Cotham & < Conglomerate................... 2 0 Fish-scales and teeth.
Westbury Pteria contorta (Portl.),
Beds). Chlamys valoniensis
; : :
Clay, blues 6. 0 42 Det) Cina
iar 4 cus Moore, Pollicipes
| sheticus Moore, fish-
\e L scales.
Rn Uc OO aRe
CARBONIFEROUS. Limestone: seen about...... 15 O Dip, 35° N.W.

The foregoing details are derived (but have been checked) from
Moore’s observations recorded in the Quarterly Journal of this
Society for 1861, vol. xvii, p. 497, and in Prof. T. Rupert Jones’s
“Monograph of the Fossil Hsthericw’*: for Moore sent specimens of
Estheria to Prof. Jones for identification and notice in his Mono-
graph, along with stratigraphical details.

Section at Hapsford Mills.—The last section to be noticed
in this area is in the quarry which has been partly utilized for a
saw-pit, just before turning into the by-lane leading to the Elm

road.

1 BF, A. Bather, Geol. Mag. dec. 5, vol. vi (1909) p. 109; and ddid. vol. vii

(1910) p. 114.
2 Palxont. Soc. 1862, pp. 73-74.

Vol. 67.] WEST, MID, AND EAST SOMERSET. 65

Section at Hapsrorp Mitts.

Thickness in feet inches.
Ctenostreon pectini-

INFERIOR } i Limestone, rubbly, about. 3 jforme (Schloth.), Tri-

OoxiTE. chites, Acanthothyris
re ge NAN Non-sequence. spinosa (Schloth.).
2. Limestones, white. The
LANGPORT top-bed is well bored. The 6

BEDs. borings may be discerned
from the floor of the quarry.

( 3.Conglomerate: according 25 al: Lycopodites lanceo-

BOP MUGOTE), oetace hice het latus (Brodie), fish-

4. Limestones, marly, a scales. In the Moore

CoTHAM conglomeratic, harder 0 Collection at Bath

BEDs. the base, with chelly there is a specimen of

layers...

in rock from about

5. Marls, black and ‘brown, 3
this horizon.!

white-banded ......... .....
6. Clay, blue, with pebbles...
be Conglomerate paar tel ae

x a pupa-case embedded
0

8. Conglomeraté .......:.....-.

9: Clay, hues .3 ons es

W 10; Conglomerate® 0/22 ie
eu eY) 2 1 Olay, bine /.2...

0) 2
Bes. 12. Conglomerate, “8 to 14 a ( Acrodus minimus Ag.
inches.. by Gyrolepis albertiAs.
13. Clay, tough, ‘bluish ......... 0 22 and a number of
14, Conglomerate and clay, 0 20) 0 9 minute teeth obtained
todinches 2... ee. by washing.

Bane ~~~ Uneconformity.
CaRBONIFEROUS. Limestone. Highly inclined, but with a well-planed top.

From fallen blocks of conglomerate Moore obtained Pteria con-
torta (Portl.), Dimyodon intus-striatus (Emmerich), Orbiculoidea?
townshendi (Forbes), and Ostrea fimbriuta Moore. Moore was of
opinion that these conglomerates had formed slowly, and the
condition of the shells, vertebrate-remains, and pebbles certainly
supports this view.

My record differs little from Moore’s.” He failed to find Estherice
or plant-remains in Bed 4.° In some pieces of the rock, however,
remains of lycopods are not uncommon,* and it is interesting to
note that this is the farthest place south at which they have
been found up till now (1910). Moore also expressed some
doubt as to the white limestones being ‘ White Lias’; but he need
not have done so, for they are quite typical. The uppermost
stratum of the Langport Beds is noticeably bored and waterworn.

(B) The Radstock Area.

Nowhere in this part of Kast Somerset are the Rhetic deposits
very thick, and at Upper Vobster all that represents them is an
occasional thin stratum, with fish-scales, etc. adhering to the
surface of the Carboniferous Limestone.?

1 Mr. W. H. Wickes has a similar specimen of ‘ a pupa-case of a dragon-fly ’
from tbe ‘ Naiadites Bed’ of ‘ Redland (New Clifton), Bristol.’

2 Q. J. G. S. vol. xxiii (1867) pp. 490-491. 3 Ibid. p. 491.

4 Proc. Cutteswold Nat. F. C. vol. xvi (1909) p. 226; and Proc. Geol.
Assoc vol. xxi (1909) p. 223.

> Proc. Geol. Assoc. vol. xxi (1909) p. 222.

Q.J.G. 8. No. 265. F

66

exposed in the railway-cutting at Chilcompton.

MR. Le. RICHAKDSON ON THE RH ATIC OF

| Feb. 1911,

The principal section in the Radstock district is that which is

briefly noticed by Mr. H. B. Woodward.’

RH ATIC.

—— ee ee SE

WESTBURY BEDs.

ARR RAR RRO

KEUPER.

ie

It has been very

SECTION IN CHILCOMPTON RAILWAY-CUTTING.

Thickness in feet inches.

Limestones, rubbly, white,
3 mixed with marl and clay ts
fe o ai Se@i i.e eee eee
oF Jbimestone esc fyede.c cere 0
ois Marly clay or rubble ............ -0
A Limestone, usually in ie ero
a beds ..4-..c2 a. .6 eee
Clay, tough, black and brownish.
Cotham Marble. ‘Typical
a arborescent form ee:
top: 5 to 9 niches os eee
Ne Marls, pale greenish - yellow,
a 2. } darker in places, especially :\
oa the base ........
Limestone, pale - yellow ‘and
5 bluish, argillaceous and very
B conspicuous, with a _ thin,
° grevish-green, rather gritty
2 layer above it, containing fish-
remains: 0 to 8 inches .........
4 pee marly, passing ae
*¢ into

5a. Shales, black, marly ..

(fun in thin layers, pe
Clay partings (fs. eee

6) Shalesblack 15 yen.. ceeeee

Limestone, grey, micaceous,
7.) arenaceous

ee © wv

with clay-partings ;
ous.

conspicu-

a =
Or

———

cae, black, thinly-laminated . 2
4. ( Shales black, non-laminated ... 1
Bone-Bed. Greenish earthy
limestone, crowded with the
L 112 usual fish-remains, and con-
poe a few derived frag-

P8to
1

ments of Tea-green Marl;
quartz-pebbles : { to 22 inches.
Non-sequence.
(Marl, soft, greenish: 4 to 8
inches .....
Marlstone,
grey,
inches
Marls and earthy marlstones .... 3
Marlstone, ear as 3 tou 0
inches .....
Marls, soft, bluish-g green :

; Marls, red.

0
earthy, greenish-

TEA- conspicuous: 2 to 6-0
_ ( GREEN
i Maris.
4

| n: about 8
RED
| Marts.

in several layers 0

CO Gb i=)

3 1 seen.

0)
4 10

nemann), Protocardia

P {fnentin, ? ewaldi (Bor-
2
rhetica (Merian).

0

3 1 Isocyprina ewaldi, Chla-
mys valoniensis (Defr.).

0)
O
( Saurichthys acuminatus
| Ag., Sargodon tomicus
1 Phen. » Gyrolepis alberti
Ag., Acredus minimus
Ag., fish-vertebra, and
_ coprolites.

6 6
6
4.
0
5
0
WB

1 «Geology of East Somerset & the Bristol Coal-Fields’ Mem. Geol. Surv.

1876, p. 79.

Vol. 67.] WEST, MID, AND EAST SOMERSET. 67

The Pteria-contorta Shales are very thin here, and the feeble
development of the usually-associated hard beds is at once notice-
able. There are no Sully Beds, but the Bone-Bed is particularly
rich in vertebrate remains, and reminds the observer very forcibly
of the ‘thin’ portion of the Lilliput Bone-Bed (Chipping Sodbury).

The Westbury Beds are represented, and are easily separable from
the Langport Beds—the Cotham Marble being typically developed
and readily accessible. Mr. Woodward recorded its occurrence here,
but was unable to detect it an situ. ‘The bed, however, is in its usual
position, and has the peculiarly tough clay-bed immediately above.
Except for the intervention of two more or less regular limestone-
beds, the rubbly deposits of the Langport Beds—crowded with
fossils—follow at once. Rubbly and more fossiliferous limestones
usually occur in the lower portion of the Langport Beds in East
Somerset north of the Mendip Hills, and in South Gloucestershire.

There are no sections of the Rhetic in the neighbourhood of
Kailmersdon, other than those of the uppermost strata of the Langport
Beds in the Lias quarries.

Foxcote railway-cutting.—In the railway-cutting north
of Foxcote, some 3 miles up the line from Radstock in the
direction of Bath, the Rhetic was formerly exposed, and Mr. H. B.
‘Woodward assigned a thickness of about 64 feet to the Tea-green
Marls and 12 feet to the Pteria-contorta Shales (op. cat. p. 77).

The Rhetic Bone-Bed, pyritic and full of fish-remains, was
passed through in the sinking of the Dunkerton-Colliery shaft,
near Comerton, and certain of the beds were also displayed in the
wailway-cutting immediately to the west.

SECTION IN THE RaAatLuway-CuTtTine AT DUNKERTON COLLIERY.
Thickness in feet inches.

Cotham Marble. Typical
1 | development. (Pieces on bo i
the bank, but not in sitw.)
2 to ; Marls, pale _ greenish -
At.d evellowi: 5: Si ascia. eek eee — — f{
Shales, black: seen 2 or 3 9 6} en contorta
feet: Ra eR eee (Portl.).

CoTHAM
BeEpDs.

Sandstones and __ shales,
0 10 Fish-remains.

| brown, micaceous, with
Bas. clayey shale-partings......
Shales, black, laminated ... 1 8

Shale, black, clayey ......... 0 6 ( Acrodus minimus Ag.,
Bone-Bed. Soft grit: Gyrolepisalberti Ag.,
O;bo: 2amehes: 25, 5.0.2 +7... ; Saurichthys acumi-
Non-sequence. natus Ag.

1. Clay, greenish, marly ...... OF 16

2. Clay, brown, marly ......... 0 10

. {vet beds of hard, greenish-

MY IVY IIIS

yellow, blue-centred marl-

stone. — — ?
Marls, brownish and. green-

6. § ish... ate & ; oaae :
Rep MaRts. Marls, BEdVRL Gd saute — — ?

Mr. H. B. Woodward has briefly noticed this section.}

1 ‘Summary of Progress for 1907’ Mem. Geol. Surv. 1908, pp. 155-56.
F 2

GREEN 5
MaRLs.

68 MR. L. RICHARDSON ON THE RHETIC OF _ |[Feb. tort,

(C) The Stone-Easton Outlier.

Where the Rhetic impinges on the Paleozoic rocks, its deposits
frequently become conglomeratic, and in this neighbourhood sand-
stones are more in evidence than usual,

The principal sections in the district now open are at the
Emborough Fullers’-Earth Works. They have been described by
Prof. C. Lloyd Morgan & Prof. 8. H. Reynolds’; but, as one of
the primary objects of this paper is to bring the various sections.
into line, it is impossible to avoid some amount of recapitulation.

Referring to the sketch-map given by these authors, in exposures.
9 & 10 the Tea-green Marls, which are worked for Fullers’ Earth, are
seen overlain by sandstone. The bottom-portion of this sandstone,
which is conglomeratic and contains fish-scales, rests, according to.
Prof. Lloyd Morgan & Prof. Reynolds, upon an eroded surface
of the Tea-green Marls. Section 12 of these authors affords
the best exposition of the beds: in it the top-bed is a sandstone, of
which a thickness of 24 feet is visible. This sandstone-bed floors.
the contiguous section, where it is overlain by 3 feet of compact
pale or mottled clay: this is doubtless on the horizon of Beds 2 to 4
of the Chilecompton section. Prof. Lloyd Morgan & Prof. Reynolds.
did not notice any Cotham Marble; but it occurs in the outlier and
should come, of course, between the ‘compact or mottled clay’ and
the Langport Beds or White Lias proper.

SEQUENCE AT THE EmBporoucH FULLERS-EartH WORKS.
Thickness in feet inches.

o§ a (In pieces on the surface
4/3 nae of the fields.)
Bs (i? Clay, toush, blaek: sc. .n-2 Oy
5 ; i Cobham Manbiley careers OT |
v (In Section 12 of Lloyd

ae
Aa Morgan & Reynolds.)
EC organ y s.

ee to ah Marl, cons ble : seen : 3 10
3 fee? ... renee sea Se
5 4 10
( 5a (Sandstone, grey, micaceous. : a
E & A Section 12 of Li..M. & R.) eae ue
ac b. (Sandstone: estimate............ 4, on CMe
ae 6. Shale, pale-grey, marly ......

Pleuromya sp.
{ Usual vertebrate-.

0 contorta (Portl.),
3
remains.

8

Sandstone, with layer of 0
‘beef’ on the top

(: el 8. Shales, black, weathering grey. 1
j | aa) Sandstone, yellowish. brown : ‘t Re Ge
Le Ve bs OMomamnic hee meter 2
= eS J 10. Shale, black: average ......... 0 8
S 5 i Sandstone. ace -ec per «Ox
D 12. Shales, black . 1 ungoey 0) ; :
= Sandstone, laminated some- Crowded Teed
13. times, at others conglomer- 0 54 remains, notably

atic, containing small pebbles
of Carboniferous Limestone.

14. Sandstone, false-bedded ...... 1
15 The Bone-Bed—tThe coarse ; 0 5 { Usual vertebrate-
| ~“*? conglomeratic base to Bed 14 remains.

Spherodus and
Lepidotus.

LOW) LZ

Meazoreent Van] Saeeeeeeee eee ane OmO -
KEUPER. § the

1 Proe. Bristol Nat. Soe. ser. 3, vol. ix (1899-1901) pp. 109-17.

Vol. 67.] WEST, MID, AND EAST SOMERSET, 69

The section in the road-cutting near Old Down Inn is quite
overgrown; but portions of that in the railway-cutting, which
has been described by the Rev. H. H. Winwood ! and by Mr. H. B.
Woodward,’ are still visible.

(D) The Hinton-Blewet Area.

In this ‘ outlier’ the Tea-green Marls are about 11 feet thick, and
the Pteria-contorta Shales about 10 feet.

In the lane leading from Hinton-Blewet to Shortwood Common,
the Cotham Marble and other deposits composing the Cotham Beds
can be seen, together with the underlying black shales and associated
limestones and sandstones composing the. Westbury Beds, and then
- the Tea-green and Red Marls; but the best exposure of the Péerta-
contorta Shales in the outlier is in the steep bank on the west side
of the lane that leads from the Cross Roads on Burledge Hill to
Bishop’s Sutton, Here was discovered a fine development of the
Cotham Marble, and a limestone-bed comparable with the Pecten-
Limestone of Chilcompton, only in places pyritic and full of fish-
remains,

(E) The Harptree Area.

At Harptree Hill, Triassic, Rheetic, and Liassic deposits occur
in a hollow that was excavated out of Old Red Sandstone and
Carboniferous Limestone. The Old Red no doubt furnished the
arenaceous material of which the Rhetic deposits are here mainly
composed, and most likely percolating waters with silica in solution
have brought about the partial silification of the superincumbent
Liassic deposits.

These abnormal facies of the Rhetie and Liassic strata here
occasioned considerable difficulty in their early correlation. Thus
Thomas Weaver regarded them as being of the same age as the
Blackdown Beds (Selbornian)*; Buckland & Conybeare thought
them possibly comparable with the Dolomitic Conglomerate
(Keuper)*; but De la Beche detected their partial Liassic age,’
and Mr. H. B. Woodward separated them as Rhetic and Liassic.°*

There is only one section open now (1905), and that is the
celebrated ‘pot.’ or ‘swallet-hole,’ about half-way between East
Harptree and the Castle of Comfort.

‘It is about 60 feet in diameter at the mouth, is funnel-shaped, and about
20 to 80 feet in depth. It is evidently a natural “pot” or ‘“ swallet-hole.”
The section consists almost entirely of massive bedded chert, occurring in
layers of from 1 to 3 feet in thickness, standing out sharply, but sometimes

weathering sandy at the exterior, and separated by thin clayey beds an inch or
two in thickness. The beds are coated here and there with quartz crystals.’ 7

1 Proc. Bath Nat. Hist. & Ant. F. C. vol. iii (187477) pp. 300-304.

2 “Geology of East Somerset & the Bristol Coal-Fields’ Mem. Geol. Surv.
1876, p. 79 & pl. iv.

3 Trans. Geol. Soc. ser. 2, vol. i (1824) p. 365. 4 Ibid. p. 294.

> Mem. Geol. Surv. vol. i (1846) p. 277.

° ‘Geology of East Somerset & the Bristol Coal-Fields’ Mem. Geol. Surv.
1876, p. 105; see also p. 108.

7 “The Jurassic Rocks of England: the Lias of England & Wales’ vol. iii
(1893) p. 124.

70 MR. L, RICHARDSON ON THE RHZTIC OF [Feb. 1911,

The higher beds are of megastomatos hemera,' and I collected
from them Radula pectinordes (Sowerby), Myoconcha psilonott
Quenstedt, and Caloceras cf. johnstoni (Sow.).

The precise junction of the Lower Lias with the Rheetic cannot be
determined, as there are no sections now open ; but, below the cherty
beds, ‘near the cottage at Harptree Hill, Mr. H. B. Woodward
observed ‘hardened reddish-brown micaceous sand with Pullastra
arenicola,’ and in the same neighbourhood he also obtained Pteria
contorta and Chlamys valoniensis.

Even the Keuper is cherty, as can be readily seen in the old
quarry near Eastwood House, East Harptree; and thus it is
evident that the influence of the Old Red Sandstone of the North
and EKgar Hills has made itself extensively felt.

(F) The Nempnet Outliers.

(1) Introduction.—The Nempnet outliers are situated between
the Carboniferous-Limestone masses of Broadfield Down and the
Mendip Hills, which are here only some 3 miles apart.

The red marls in the Vale of Wrington show frequent evidence
of the proximity of the Paleozoic rocks, in the shape of massive
conglomerates, intercalated sandstones, and derived fragments of
Carboniferous rocks. The Lias, which reposes in hollows in the
Carboniferous Limestone of Broadfield Down, is also frequently
conglomeratic, and the mass partakes of the nature of the Sutton
Stone of Glamorganshire. On Harptree Hill, in the Mendips again,
as already mentioned, are peculiarly-cherty Liassic beds; and so it
is not surprising to find that, in the intervening area, on the
Nempnet Hills, conglomerates of Rhetic age occur.

The Red Marls with their associated sandstones, and bands of
greenish-grey marl in their upper portion, are succeeded by the
Keuper Tea-green Marls, and these in turn by the Pteria-contorta
Shales. Lack of sections prevented me from ascertaining whether
there was any Bone-Bed present, or the nature of the Cotham Beds ;
but the Langport Beds are typically developed, and exposed in nume-
rous quarries. There are no Watchet Beds, and the Pleuromya-
Limestones of the Lower Lias follow the Langport Beds at once.

The interesting feature of the outliers, at least of the Nempnet-
Butcombe outlier, is the occurrence of massive conglomerates, which
in places extend upwards—certainly from within a very short
distance of the top of the Tea-green Marls—into the Langport
Beds, if not higher, replacing, where they occur, the greater part of
the Pteria-contorta Shales, the Cotham Beds, as well as the Lang-
_port Beds. The‘ Butcombe Conglomerates,’ as these clastic accumu-
lations may be termed, are well exposed at Cuckoo’s Nest (half-way
between Butcombe and Nempnet) and near Butcombe Church. The
part exposed at the former place largely replaces the Pteria-con-
torta Shales, as it contains fragments of vertebrate-remains, Chlamys
valoniensis (Defrance), and Pteria contorta (Portlock).

For the convenience of the future student, the details which 1

1 « Geology in the Field’ (Jubilee vol. Geol. Assoc.) pt. ii, 1910, p. 336.

Vol, 67.| WES, MID, AND EAST SOMERSET. 71

obtained may be given in the order in which they would be noted if
a walk were taken from Chew Stoke over Breach Hill, past Nempnet
and Butcombe Church, to near Pigeon House, and thence back again
by way of Butcombe and Nempnet Farm, West Stroud, and Grubble
and Pear-Tree Hills.

Brief remarks on the beds under consideration in the Nempnet
outliers are contained in the Geological Survey Memoir on East
Somerset (1876, pp. 79-80).

Gi) Stratigraphical Details.

Breach- Hill outlier.—This hill is capped with Lower Lias.
At the hamlet is a quarry showing the Pleuromya Beds resting upon
the Sun-Bed of the White Lias proper. In the steep bank above
the road leading off the hill in the direction of Chew Stoke, pieces
of a Pecten Limestone (containing, with the characteristic lamelli-
branch Pieromya crowcombera Moore, Placunopsis alpina and Gyro-
lepis albertc) and of a yellow sandstone, an inch thick, were found ;
while below are traces of the Tea-green Marls and a fine section
of the Red Marls. Similar beds are seen in the lane leading down
the western flank of the hill to Dewdown Farm.

Nempnet-Butcombe outlier.—A succession similar to that
seen in the above-mentioned lane is to be observed in ascending the
hill opposite: the Tea-green Marls being apparently but 6 feet thick,
and the Pterza-contorta Shales only 8 feet. The Langport Beds are
exposed in a quarry in the field on the right, where the Pleuromya-
and Ostrea-Beds are seen above them.

At Cuckoo’s Nest the conglomerates for which that locality is
notable are excellently exposed. In descending the lane, the
succession is noted as follows :—

( Conglomerate, composed of pebbles of Carboniferous
| Limestone embedded in a matrix of shell-débris and
( Butcombe | calcite, through which are sparsely distributed fish-

| Conglom-< scales and teeth, coprolites, and fragments of bone.
RR ae | erate. The shell-fragments are best seen on a weathered
ness surface, and are of Chlamys valoniensis, Isocy-

BEDs |_prina, ete. Ft. ins.
; | eae, rarely conglomeratic, containing aio 3
infrequently the usual Rhetic fossils ae
Shales, black ; comparatively thin.
TEA-GREEN MARLs. Marls, greenish.

Between Cuckoo’s Nest and Nempnet Farm is a large quarry in
the Johnstoni-, Ostrea-, and Pleuwromya-Beds, with the Sun-Bed and
immediately-underlying ‘ Cockle-Bed’ at the base. This Cockle-
Bed is a peculiar, cavernous White-Lias limestone.

In the steep bank north-east of Butcombe Church the Butcombe
Conglomerate must be at least 8 feet thick, and contains some very
big pebbles of Carboniferous Limestone.

Pigeon-House outlier.—In this outlier the Pteria-contorta
Shales are exposed at several places in the lane running along the
northern side; and in a watercourse, under the ‘o’ of House in
‘Pigeon House’ on the Geological Survey map, Sheet xix, I found
a Pecten Limestone.

(72 MR. L. RICHARDSON ON THE RHZTIC oF _—[ Feb, 1911,

Grubble-Hill outlier.—Portions of the Red Marls, Tea-
green Marls, Pteria-contorta Shales (with a Pecten Limestone, 1 to 3
inches thick, and Volseila sp. indet., Saurichthys |tooth], and fish-
scales), and the pale marls of the Cotham Beds are to be observed
in the sides of the lane which climbs the western flank of the
outlier ; while in a quarry at the eastern end are seen about 4 feet
of Langport Beds overlain by certain Lower Liassic deposits, which
correspond—so far as the upward succession goes—bed for bed with
the equivalent rocks in the quarries on Breach Hill, and between
Cuckoo’s Nest and Nempnet Farm.

Banwell outlier.—There are no exposures of the Rhetic on
this outlier, but the Planorbis Beds are finely displayed in a quarry
near Knightcote.

EXPLANATION OF PLATES LIV.

Puate I.
View of Blue Anchor Point, showing the anticlinal arrangement of the
deposits.
Puate II.

Foreshore section near the first gypsum-workings, Blue Anchor Point,

Puatez III.

Fig. 1. The upper part of the cliff at Blue Anchor Point.
2. The lower part of the cliff at the same locality.

Prats IV.
The Warren-Farm section: Upper Keuper Marls.

Discussion.

Mr. 8. 8. Srantny said he thought that the point to be decided
was whether the Sully Beds were conformable to the superimposed
Rhetic strata or to the Upper Keuper below them. So far as his
own observations went in the Southam, Ufton, Harbury, and
Chesterton parishes, where the beds occurred at the surface, and
also in the Stratford-on-Avon vicinity, they were conformable to
the Rhetic. With regard to the Stratford neighbourhood, the
speaker thought that there the beds showed an estuarine origin,
as fossil insects were fairly abundant. Neither the late Rev. P.
B. Brodie nor he himself had ever found anything like an insect in
the Harbury neighbourhood; and so it might perhaps be inferred
that there the beds were deposited at a greater distance from
any coast. Between Harbury and Whitnash,. on the Roman Fosse
Road, two or three very interesting faults were noticeable. In no
case could the Sully Beds be found conformable to the New Red
Sandstone, so far as the knowledge of the speaker went. The
localities to which he referred were about 4 miles from Leamington.
The cutting on the Great Western Railway, as that line approached
Harbury from Leamington, commenced on the west in the New
Red Series, and passed through the Rhetic into the Lower Lias:
the contour and the dip made almost a right angle.

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

Fig. 1.—THE Upper PART OF THE CLIFF AT BLUE ANCHOR POINT.

| Lower
Lias.

Watchet

Beds.

Langport
Beds.

Cothain
Beds.

im R. photogr.

Fig 2.—THeE Lower PART OF THE CLIFF AT BLUE ANCHOoR PoINT.
[Keuper Marls with veins of gypsum. ]

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Vol. 67.] WEST, MID, AND EAST SOMERSET, 73

Dr, J. E. Marr expressed the desire that names ending in ‘ian’ *
should, so far as possible, be confined to those larger divisions
which in the nomenclature of the International Geological Congress
were called ‘series.’ As a teacher, he would suggest that less
confusion would be introduced if the Author adopted the term
‘Rheetian’ for what he called ‘ Rhetic,’ and used the terms
‘Somerset Beds’ and ‘ Lilstock-Sully Beds’ for what appeared as
‘Somersetian ” and ‘ Rhetian’ in his stratigraphical table. Each
of the two last-named divisions included only about 60 feet of rock,
and they were, therefore, hardly ‘series’ in the accepted sense of
that term.

Dr. Srranan, while expressing his sense of the value of the
Author’s highly detailed examination of Rheetic sections, still
found himself unable to accept the definition of the Rhetic base
given in this paper. Previously to the re-survey of South Wales
the Tea-green Marls had been included in the Rhetic. They passed,
however, so imperceptibly down into the underlying Red Marls,
that it was obviously impossible to separate them with precision.
On the other hand, there existed between these green veds and
the overlying Black Shales a well-marked plane of separation which
was recognizable over a large areain England and Wales. No fossils,
beyond some remains of fishes and an oyster, were known to occur
below this plane in South Wales, whereas a Rhetic fauna abounded
above it—facts which, taken in conjunction with the occurrence of
a conglomeratic Bone-Bed resting on the plane, indicated a sudden
invasion of the sea. Subsequently to the re-survey the Author
recorded Rheetic fossils from below this plane, the account of their
occurrence, however, being such as to leave him (the speaker)
under the impression that they had been found on the top of the
green beds, not in them. If, as the Author now again maintained,
they occurred in the green beds, the fact would be interesting as
showing that a prevalence of estuarine conditions enabled some of
the Rhetic molluscs to enter the region before the general incursion
of the Rheetic fauna. How nice was the balance between estuarine
and open-sea conditions was indicated by a temporary recurrence
of sediments of Keuper-Marl type in the Upper Rhetic. The
appearance, however, in the green beds of a few forerunners of
the Kheetic fauna did not convince the speaker that a well-marked
stratigraphical and paleontological horizon should be abandoned in

1 [The following was the classification suggested, with the exception of two
alterations: the replacement of the term Westbury Beds by Cotham
Beds (III), and that of Lilstock Beds by Westbury Beds (IV) :—

~ Lis. Hettangian. Ostrea Beds, etc.
/ I. Watchet Beds (‘ Marly Beds of the White
Seaver sekiaa Tas ’).
Ruane. 3 ‘) II. Langport Beds (White Lias proper).
: IIL. Cotham Beds (Upper Rhetic).

| IV. We
. : stbury Beds (Black Shales).
ea V. Snlly Beds (Fossiliferous Grey Marls).
Kevurrr. Keuperian. Tea-green and Grey Marls. Red Marls.
L. R., February 16th, 1911.)

Ww

74 THE RHATIC OF WEST, MID, AND HAST SOMERSET. | Feb. 1911,

favour of one which was wholly indefinite, as the base of the
Rheetic group.

The Prestpent (Prof. Warts) expressed his sense of the importance
of the Author’s work and of the interest of the non-sequences
revealed by a close study of the Jurassic and Rhetic zones. In the
matter of mapping, he thought that it would always be necessary
to carry on the practice of field-mapping by means of physical
characters, the true position of the beds being checked by palzonto-
logical evidence.

The Aurnor, in reply, said that more field-work was necessary
before the precise horizon at which insect-remains occurred could
be indicated. Referring to Mr. Stanley’s remarks, he was not
aware of any facts to suggest that there was a non-sequence
between the Red Marls and the Tea-green Marls in Warwickshire ;
but he did hold that there was a gap between the latter and the
Black Shales—he thought that the Sully Beds and the bottom
portion of the Black-Shale subdivision were wanting.

With regard to Aust Cliff, the Author held that the Sully Beds
and practically the whole of the infra-Bone-Bed deposits were
absent, and those who knew from personal investigation the
ordinary phenomena associated with non-sequences would appreciate
the significance of rolled masses of Tea-green Marl embedded in
the Bone-Bed there.

In reply to a question put by Mr. Monckton, the Author
remarked that most Rheetic field-geologists felt that the White
lias proper ought to be grouped with the Rheetic; and yet, at
the same time, they realized that it and the underlying Westbury
Beds and overlying Watchet Beds were very distinct from the
Pteria-contorta Black Shales. Hence the suggested dual division
of the Rhetic Series into Rhetian and Somersetian: a division
supported both upon lithological and upon paleeozoological grounds.

In reply to Dr. Marr, the Author thought that if he had altered
the term ‘ Rhetic’ to ‘ Rhetian,’ it would have complicated the
nomenclature. The term ‘ Rhetic,’ according to the proposed
classification, would be available for colloquial purposes in the same
way as the terms ‘Inferior Oolite’ and ‘ Lias’: otherwise, such
well-known terms as ‘Lias’ would have to be modified. ‘Rheetian’
and ‘Somersetian’ came into line with such terms as ‘ Hettangian,’
‘ Aalenian,’ ‘ Bajocian,’ etc.

In reply to Dr. Strahan, the Author exhibited a specimen of
Pieria contorta from a horizon well down in the Sully Beds at
Lilstock in West Somerset, and specimens of this and other fossils
from the equivalent beds at Cadoxton and Sully in Glamorgan.
Prof. Boyd Dawkins had also recorded characteristic Rheetic fossils
from the Sully Beds, or, as they were called at the time, the ‘ Grey
Marls’ ( pars), of Watchet. He agreed with Dr. Strahan and the
President that, for mapping purposes, the Sully Beds must be
associated with the Tea-green Marls (Keuper). The occurrence in
them of Rheetic fossils was of purely scientitic interest.

Vol.67.] THE PERMIAN AND TRIAS OF NOTTINGHAMSHIRE.

~]

Or

2. The Rurartonsure of the Purmian to the Tras in NotrineHam-
SHIRE.. By Rozurr Lionet Suertocr, B.Sc., A.R.C.Sc., F.G.S.
(Communicated by permission of the Director of the Geological
Survey. Read December 21st, 1910.)

[Prare V—-Gxoxocicat Map. |

ConTENTS.

Page

T.. Introckuetiontect 3. Ria settee crete ek ete ds ancessastonsbe bes 7d
PE Sir eG eecpiiy ete eth oh hat ena tdak an cv ene sceecee= 79
III. Paleontology of the Upper Magnesian Limestone ............ 105
WIS, Chee REID NHS oon, Soc cee er ee haa ceeacs cuccuressssatns 110
A emia RN 82. a eke ee ee Ee ease aS tbs; wasps dace es 114
Pate Evia beereToapabhy *< 22. 0 tse ee ie cee sane cas cos cslenncnncinms cos 114

I. Inrropvuction.

_ Tue Permian System is generally considered? to be represented in
England by two distinct divisions, corresponding to the Zechstein and
the Rothliegende of Germany. The English Rothliegende is further
regarded as of two types: that of the Midland Counties, or Salopian
type, and that of Collyhurst (Lancashire). The Zechstein is
supposed to be represented by the Magnesian Limestone Series of
the North-Eastern counties, together with some scanty deposits
near Manchester above the Collyhurst Sandstone, and in Cum-
berland. The red beds of Devon, which are of doubtful age, need
not be considered here.

In recent years the Permian age of many of the deposits of
Salopian type has been called in question, and it has been shown *
that, in many cases, they are united to the Carboniferous System
below and are unconformable to the Trias above.

In the case of the English Zechstein the beds are magnesian
limestones, marls, and sands, and the limestones contain fossils which
have been recognized as Permian, This division is chiefly repre-
sented by the long belt of strata which stretches continuously
from the Northumberland and Durham coast, through Yorkshire,
as far south as Nottingham. The Permian in this region differs
from the English Rothliegende, not only in lithological character,
but in its relationship to the beds below ; for it has been known for
a long time that it is markedly unconformable to the Carboniferous
upon which it rests.

The nature of the upper boundary of the Permian is, however,

1 Thesis approved for the Degree of Doctor of Science in the University of
London.

2 See E. Hull, 1869. [For full details of references, see the Bibliography,
§ VI, p. 114.]

3 T. C. Cantrill, 1895; and W. Gibson, 1901.

76 MR. R. L. SHERLOCK ON THE RELATIONSHIP OF THE [ Feb. IgII,

less clear. It is usually stated that there is an unconformable
overlap of the Permian by the Trias in this area; but several
geologists, and notably the late Edward Wilson, thought that the
gap between Permian and Trias was much overestimated, and that
there might even be an actual passage between them.

In this paper I attempt to prove the upward passage of the
Middle Permian Marls into Bunter in Nottinghamshire, then, using
the Middle Marl as a datum-line, to trace it northwards and to
note its relations to the beds above and below and any hthological
changes of the strata. The result of this investigation is to show
that the ‘ Bunter’ of Nottinghamshire is contemporaneous with the
upper part of the Permian of Yorkshire and Durham.

During the years 1903-7 I have mapped, on the 6-inch scale,
the Permian outcrop (together with much of the Trias) from its
southern limit at Nottingham as far north as Market Warsop.
The area of the Permian outcrop is far too great to permit of the
examination of the whole in equal detail, but the entire length of
it has been traversed, and the chief sections, recorded by Aveline
and other geologists, have been examined. In addition, the
Permian has been seen at St. Bee’s Head and at Penrith.

The chief importance of the work in Nottinghamshire lies in its
application to the correlation of the New Red deposits in other
districts. A brief account is, therefore, given of the rest of the
Permo-Triassic outcrop as far as Northumberland, as well as the
supposed equivalent deposits of Cumberland and Manchester, and
new correlations with the Nottingham succession are attempted.
The paleontology of the Upper Magnesian Limestone is examined,
and is shown to lend some support to the new views.

The first considerable paper on the Permian of the north-eastern
district is that of Sedgwick,’ on the geological relations of the
Magnesian Limestone, which describes the beds from Northumber-
land to Nottingham. Later, attention was directed chiefly to the
northern part of the outcrop; but in 1861 J. W. Kirkby published an
important paper in this Journal, ‘ On the Permian Rocks of South
Yorkshire ; & on their Paleontological Relations.’

Geological Survey maps have been issued of the whole area, and
memoirs describing the southern half of the outcrop have been
published. Recently, two maps and memoirs embodying the results
of a re-survey of the neighbourhood of Nottingham have been
published.

A paper by Edward Wilson, entitled ‘The Permian Formation in
the North-East of England, and dealing chiefly with the mode
of origin of the deposits, appeared in the ‘ Midland Naturalist’
vol iv (1381) pps O75 121 ete:

In the year 1877 there were several letters in the ‘ Geological
Magazine’ on the relations of the Permian to the Trias near
Nottingham. Aveline,* who opened the discussion, referred to the

1 Trans. Geol. Soe. ser. 2, vol. ili, pt. i (1829) pp. 37-124.
2 Geol. Mag. dec. 2, vol. iv (1877) pp. 155-56.

Vol. 67.] | PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. ie

views held by some geologists, that the Permian was perfectly
conformable to the Trias in the Nottingham district. To this he
objected, on the ground that the Bunter overlaps the divisions of
the Permian successively from north to south. Wilson,’ in reply,
pointed out that the successive disappearance of the Permian divi-
sions might be due to conformable overlap, and as an illustration,
he cited the case of the thinning of the Marl Slate Series? from
60 or 70 feet of shales to ZO feet of sandstones and then to nil,
between the basal breccia and the succeeding limestone. As a
result, the Magnesian Limestone appears to overlap the Marl
Slates ; he remarks, however, that this points, not to a break, but
to the presence of a Permian shore-line to the south.

The Rev. A. Irving ® supported Wilson, and thought that, while
there might be a slight unconformity lovally between Permian and
Bunter, such breaks were not greater than those that occurred
between individual beds of the Permian, and especially between
the Middle Marls and the Lower Limestone. In Aveline’s* reply
he states that he did not consider the Permo-Bunter break an
important one, and would not give an opinion as to whether the
break is more important than that between the Lower Limestone
and the Middle Marls. He considers the relationship of the Permian
to the Trias an important problem yet to be worked out :—

‘If a perfect passage from the one up into the other was found, it would go

far to settle the question. As far as I know, that passage has not been found,
and, I ccntend, it does not exist in the neighbourhood of Nottingham.’

As will be seen farther on, this passage has now been found.

After Aveline’s second letter the discussion ended for the time, but
was revived in 1879-82 round the question of the age of the Pennine
uplift, and the correlation of the Lancashire and Yorkshire deposits.
Dr. Irving,’ who in the interval had been examining deposits in
other districts, modified his view of the relationship of the Bunter
to the Permian at Nottingham and considered that there must be a
break between the two. The discussion need not be turther
referred to here, as 1t does not bear closely upon the nature of the
Permo-Bunter boundary, but rather on the age of the Pennine
uplift.

Other works will be mentioned as occasion arises, and a complete
list of references will be found at the end of this paper.

Although the views here expressed on the relations of the
Permian and the Trias are opposed to those of Aveline, who mapped
much of the area for the Geological Survey, his facts are in no case
disputed, but it is hoped to show that new evidence leads to a
different interpretation of his results.

1 Geol. Mag. dec. 2, vol. iv (1877) pp. 238-40,
2 See p. 79 for table of strata.

3 Geol. Mag. dec. 2, vol. iv (1877) pp. 809-12.
4 Ibid. p. 380.

° Ibid. vol. ix (1882) p. 163.

Trent:
Alluvium

Waterstones

Pebble Beds
= Lower
Mottled
Sandstone
Middle Marl }}
Lower
Magnesian
Limestone

a _ Scale 3 miles to 1 inch

Zt
<i
=
c
ui
o.

NOTING!

2 T/TINGHAM

:

|The area, west of a north-and-south line through Bulwell, and south of an
east-and-west line through Hucknall Common, was mapped on the
6-inch scale by Dr. Walcot Gibson. ]

Vol. 67.] THE PERMIAN AND TRIAS OF NOTTINGHAMSHIRE. 79

II. SrratieRaPuy.
(1) South Nottinghamshire.

In this area the succession is as follows :—

Rilneeier (Tent a eco vee tesa ac cid As dncagct = RuaATIC,
KeupergWiarii (tye ei case stack asneet a }
: j KEuPER.
Wairenstamesh ((2)iae vaateaatises ese caer wr
Pebbles Bedsy(2yig jaccesercenct- me socweane
\ Bunter.
Lower Mottled Sandstone (f1) .........
Permian (Middle) Marl (e?) ........ ... |
Magnesian Limestone (e?) .............4. |
SMiarsli Slates (Pie a cecarem, nn aceiaocaes esos i EMEMIAN
LBP SCOE) | UE RAR oRRAG inne DARE ae SEE grein )

[The symbols in parentheses are those used on the Geological Survey maps. |

The upper divisions of the Trias may be dismissed in a few
words. ‘he Rhetic, the lowest beds of which are best seen at
Beaconhill (Newark), is sharply marked off from the Tea-green
Marls, which, as usual, form the highest beds of the Keuper. On
the other hand, the black shales seem to pass upwards, by the
incoming of limestone bands, into the Lias (well seen along the Great
Central Railway, south of East Leake Station).

The Keuper Marl presents its usual character of a red silty clay
with thin sandstone bands, which increase in thickness and number
until sandstone predominates, and the Waterstones come in.

Between the Waterstones and the Bunter Pebble Beds there is
probably a slight unconformity. This is indicated by some
discordance in strike, by a marked lithological change, and by the
presence, at certain places, of a few inches of conglomerate at the
base of the Waterstones. The absence of the Upper Mottled Sand-
stone (f°) above the Pebble Beds cannot be regarded as evidence of
an unconformity, owing to the local character of the Bunter sub-
divisions. The thickness of the Keuper Marl may be taken as from
600 to 700 feet, and that of the Waterstones as from 80 to 200 feet.

The two divisions of the Bunter differ markedly one from the
other, although there is a passage of the lower into the upper (except
at Mansfield). The Lower Mottled Sandstone is a fine-grained, rather
marly sandrock, of a deep red colour, with sometimes large yellow
patches. Rounded pebbles of the usual Bunter type are quite
absent, except in the passage-bed at the top, but it contains
thin gritty bands, which, at times, are sufficiently coarse to be
termed ‘ breccias.’ False bedding occurs, but is much less common
than in the Pebble Beds above. The Pebble Beds are considerably
false-bedded, with rounded pebbles, either scattered sporadically, or
grouped into strings or thin conglomeratic bands, and the sand is

A

coarse-grained. Near
Nottingham the beds
are yellow or buff; but
farther north they be-
come red, though of a
paler tint than the
Lower Mottled. It is
noticeable that the in-
tensity of the redness.
diminishes with the
increased size of the
sand- grains. Pebbles
and concayo-convex len-
ticles of red or green
marl may occur at any
horizon in the Bunter,
and are fairly common
in the Lower Mottled
Sandstone. ‘This sand-
stone varies in thickness
from about 30 feet at.
Nottingham to 100 feet.
near Annesley ; and the
thickness of the Pebble
Beds may be taken as
varying from 200 feet at
Nottingham to 400 feet.
at Mansfield.

The Middle Permian
Marl is a bright red
silty clay, with green
or greenish - white
bands and __ streaks,
which usually are finely
arenaceous. Its thick-
ness varies from about
10 to 20 feet.

The Magnesian Lime-
stone is composed of
small rhombs of dolo-
mite, cemented by cal-
careous matter which is
dissolved on weather-
ing, when a _ porous
sandy-looking rock of a
yellowish colour results.
So striking is the re-
semblance of the rock
to sandstone that it has
sometimes been de-
scribed as such in
records of borings, and

traced to

Same beds
290 Yds. from
Tunnel Mout

Well

Lower Mottled - ae See eee oe eee = [om a r ae Sous aac
Sandstone : oe “ c & So : fete
(Bunter)

Annesley Turnel
(900 Yards)
about 38 times the horizontal. |

Vertical scale

Aqueduct
Limestone

US

—_— x eee st
Z a icoenoccaasee ae Tam Oee mater =
es : :
SS -
aaa :
Se Se ae c E 5
ST

[Horizontal scale: 18 inches =1 mile.

Fig. 2.—Section on the Great Central Railway between Annesley and Kirkby-in-Ashfield.
Lower Gl ate i) OIE Ee Wa)

Tunnel Mouth

S

=
Sw
S
>
S
S
Liq}

Vol. 67.] | THE PERMIAN AND TRIAS OF NOTTINGHAMSHIRE. 81

confused with the Bunter above. At Nottingham the limestone
is perhaps 20 feet thick; it increases, however, in thickness north-
wards, at first slowly, but at Sutton-in-Ashfield rapidly, and then
becomes more varied in its characters. It contains a considerable
amount of insoluble sandy residue, especially near its southern
margin. Fossils are very rare, and consist of casts of lamellibranchs.

The ‘ Marl Slate’ is of local occurrence only. Near Nottingham
it is a dolomitic flagstone, which passes upwards into the Magnesian
Limestone. Fragments of plants are found in it, together with an
occasional Schizodus or Myalina.

The Breccia, which is even more local than the Marl Slate, is
well developed at the southern termination of the Permian outcrop,
marking the boundary of the Permian sea.

A little farther north, at the latitude of Kirkby-in-Ashfield, the
Marl Slate seems to be represented by grey clays, with occasional
thin bands of nearly pure limestone. ‘These latter are interesting
on account of the fossils, chiefly lamellibranchs and foraminifera,
which they contain. The grey clay, when weathered, closely re-
sembles the soils over the Coal-Measure shales, and, in the absence
of the breccia, the Permo-Carboniferous boundary becomes very
difficult to trace.

The best sections of the Permian in South Nottinghamshire are
along the Great Northern Railway (Derby & Nottingham Branch),
and in the cuttings on the Great Central and Midland Railways,
near Annesley. The former of these railway-sections was fully
described by E. Wilson in 1876, but the Great Central sections
have not been hitherto described, except very briefly by myself.’

(a) Sections on the Great Central and Midland
Railways, near Annesley.

Two railways tunnel through the Robin Hood’s Hills, 94 miles
north of Nottingham Market Place. One of these, the Great Central
main line, approaches the Mansfield Branch of the Midland Railway
obliquely, and finally passes under the latter line. The cuttings
at the extremities of the two tunnels together show a complete
succession, from almost the base of the Magnesian Limestone to
the top of the Lower Mottled Sandstone.

Following first the Great Central Railway northwards (see fig. 2,
p. 80), the line begins to cut gradually into the plain of nearly hori-
zontal Lower Mottled Sandstone. As successively lower beds are
reached the character of the strata is seen to change gradually, the
red sandrock becoming very fine-grained with a considerable increase
in the proportion of clay, and at the same time developing clay-
partings, which give it a flagey structure. At the entrance to the
tunnel, the beds at the bottom of the cutting, now about 50 feet
deep, are so fine-grained and marly that it becomes difficult to
decide whether they should be regarded as a sandy marl or as a marly

' W. Gibson & others, 1908, p. 129.
Q. J. G.S. No. 265. G

|

82 MR. R. L. SHERLOCK ON THE RELATIONSHIP OF THE [ Feb. 1911,

sandrock. These strata bear a close resemblance to the Keuper
Waterstones of Nottinghamshire. <A well, sunk by the railway
company near the mouth of the tunnel, proved the presence of the
Magnesian Limestone at a depth of 15 feet below the rails.

The tunnel itself is bricked up, but the section is continued at its
northern end. Here the marly beds, seen at the bottom of the
cutting at the southern end of the tunnel, have been brought by
the gentle dip of the strata to the top of the section. Much of this
cutting is unfortunately obscured by grass; but the constant oozing
of water from the beds causes landslips, and thus it is possible to
make out clearly the whole of the succession.

The marly sandrock of the Lower Mottled Sandstone passes
downwards into the red ‘Permian Marl’ by an increase in the
thickness of the marly partings and a corresponding diminution of
the fine-grained flags, which eventually come to be represented only
by the ‘skerries* of the Permian Marl. No true boundary can be
traced between the Permian Marl and the Lower Mottled Sand-
stone; but, for the purpose of mapping them, an arbitrary line was
taken below the last considerable sandy lenticular band.

Thus defined, the Permian Marl has a thickness of about 13 feet.
only. It rests upon the Magnesian Limestone without visible un-
conformity, but with a sharp lithological break. At the mouth of
the tunnel the top of the limestone is 4 feet above the rails, and
the low dip of about 1° brings it to the surface of the ground
400 yards from the tunnel. A little farther on the cutting forks,
and both branches show good sections of the limestone. The right-
hand branch (the Great Northern) turns northwards and becomes
parallel to the strike of the beds, so that the seetion remains in the
same part of the limestone: but the left-hand branch, which carries
the Great Central main line, turns westwards and cuts through
practically the whole thickness of the Magnesian Limestone :
the grey marls with fossiliferous limestones, which form the
lowest division of the Permian here, cropping out a little beyond
the end of the cutting.

The Midland Railway crosses over the Great Central, hence the
sections on the Midland are in slightly higher strata than those
on the Great Central. Commencing as before in the south, we find
that the lowest beds exposed along the Midland line consist of
the red sandrock seen close by at the top of the other cutting. Pro-
ceeding northwards, the rise of the land-surface causes a deepening
of the cutting and brings in increasingly higher strata, until, at
the tunnel entrance, we see at the top rather massive and coarse
reddish sandrock, which is almost the highest bed of the Lower
Mottled Sandstone, for the summit of the hill is in the Pebble Beds.

At the northern end of the Midland tunnel the sections are a
repetition of those exposed at the southern end.

These sections are of great importance, because the Permian Marl,
which is seen to pass upwards by imperceptible stages into the
Bunter, is not, as one might expect, the highest bed of the Permian
System, but is the Middle Permian Marl, that is, the marl which

Vol. 67.] | PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 83

farther north underlies the Upper Magnesian Limestone. There
has never been any question raised as to the age of this Marl,
which was traced by Aveline from Yorkshire to Nottingham ;
and detailed mapping confirms the continuity of the bed, at least
as far as from Nottingham to Warsop.

If this passage of Permian into Bunter is accepted, there is no
escape from the conclusion that the Upper Magnesian Lime-
stone of Yorkshire is of the same age as some part of
the Bunter of Nottinghamshire. Although the passage is
an apparently perfect one, it might be thought that there is a
concealed break somewhere—the break representing the higher
Permian beds of Yorkshire. The evidence for a true passage is,
however, greatly strengthened by the sections exposed along the
Great Northern and Midland Railways, between Nottingham and
Kimberley.

(6) Sections on the Great Northern and Midland
Railways, between Nottingham and Kimberley.

The Great Northern sections were fully described by Edward
Wilson in 1876, so that a brief account will suffice here.

The section shows Coal Measures unconformably overlain by a
breccia, which is succeeded by the flaggy, calcareous sandstones
with shales, known as ‘ Mar] Slates.’ These pass upwards into
the ‘Magnesian Limestone, here (as usual in South Nottingham-
shire) a flaggy rock, composed of rhombs of dolomite set in a cement
of carbonate of lime. The limestone is succeeded by red Permian
Marls, which appear to pass upwards into a mass of sandstones
with bands of marl; and these indefinite strata, which Wilson
considered to be a link between the Permian Marl and the Bunter,
and for which he therefore used the symbol ef, merge imperceptibly
into Lower Mottled Sandstone. Wilson, however, did not actually
call these indefinite strata ‘ passage-beds,’ as they required further
study. A breccia, as much as 5d feet thick, though locally absent,
was taken as the base of the true Lower Mottled; but Wilson shows
that precisely similar breccias occur well within undoubted Bunter,
as, for example, at Kimberley Knowl, close by.

It may be pointed out here that the presence of breccia in the
Lower Mottled Sandstone in the Great Northern cutting, and its
absence in the Great Central cuttings previously described, is
readily accounted for by the proximity of Kimberley to the old
shore-line of the Permian sea. The thick basal breccia of the
Permian and the sandy ‘ Marl Slates’ above it, similarly contrast
with the thin breccia followed by grey marls, found below the
Magnesian Limestone near the Great Central cuttings.

Many of the details described by Wilson can still be seen, and
the Midland Railway cutting, which is approximately parallel to
the Great Northern section, confirms the evidence of the latter.

The presence of the indefinite band of strata between the Permian
Marl and the Bunter at Kimberley, 6 miles from the Great Central
cutting, strongly confirms the idea that there is a true passage
between the two formations. ao

84 MR. R, L. SHERLOCK ON THE RELATIONSHIP OF THE [Feb. 1911,

(c) The Area south of the Great Northern Railway
(Nottingham & Derby Branch).

A little to the south of the Great Northern Railway, at Basford,
the Permian Marl ceases to be separable, and the passage-bed rests
upon the limestone for a short distance.

The small faulted outlier at Cinderhill is of interest, as a breccia-
band seen there in the quarries has been taken as marking an
unconformable junction of the Bunter with the Permian Marl.
However, further excavations have shown that the breccia does not
always lie at the base of the sandy series, but changes its horizon.

The growth of Nottingham along the Leen Valley and the com-
plicated system of faults which exists there render the strati-
graphy very difficult to make out south of Basford; but, from what
can be seen at the present time, and from the records of sewer-
sections left by Wilson and Shipman,’ it appears that the passage- .
bed and Lower Mottled combined thin out southwards. At Bob-
bers Mill the Magnesian Limestone passes rapidly into a breccia
and ends abruptly, and the Lower Mottled Sandstone overlaps it.
At Spring Close (Lenton), and also at Two Mile Houses (Basford),
there are good sections of variegated Lower Mottled Sandstone, and
that rock can be followed to the mouth of the Leen. Here the
Bunter, which strikes north and south, is dropped out of sight by
faults, proved in the workings of Clifton Colliery: with the result
that, on crossing the Trent Valley alluvium, Keuper Marl is seen at
the surface.

From the mouth of the Leen, patches of Bunter extend westwards
across the Coal Measures, which they overstep ; and at the same
time the Lower Mottled Sandstone rapidly disappears, so that Pebble
Beds come to rest directly upon the Coal Measures about a mile and
a half west of the Leen.

(d) The Area between the Great Northern Railway
(Nottingham & Derby Branch) and the Robin
Hood’s Hills.

North of the Great Northern Railway the main outcrop of the
Permian Marl follows the Leen Valley, and the junction of the
Permian with the Bunter is usually hidden by alluvium. The sur-
face of the ground is nearly flat, with a gentle eastward inclination,
agreeing in direction with the dip of the beds, the result being that
the outcrops of the thin strata are relatively wide. The flat is
bounded on the east by the escarpment of the Bunter; and it is
interesting to note that the line of feature does not agree with the
boundary of the formation—for, owing to their softness, the passage-
beds form part of the flat, and it is not until the more massive sand-
rock above crops out that an escarpment is produced. This is very
wellseen in the cutting on the Midland Railway, at the entrance to
the tunnel previously described. It is these more resistant beds

1 G. W. Lamplugh & others, Mem. Geol. Surv. 1908, pp. 27-28 & 32-33.

Vol. 67.] PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 85

that form the long spur of high ground stretching southwards from
the Robin Hood’s Hills, through Annesley Park, to near Hucknall
Torkard.

At Bulwell Spring, east of the River Leen, a 9-foot section of
the passage-bed shows very well the lenticular and inconstant
character of the strata.

Wilson * states that at Bestwood the passage-beds replace all but
8 or 10 feet of the Lower Mottled Sandstone.

During the construction of the Bulwell Viaduct for the Great
Central Railway, sections seen in the excavations were noted by
Mr. Allen,* engineer to the line, and by J. Shipman. The upper
part of the Marl was sandy, though the bottom 8 feet of the section
showed nothing but solid marl.

The best exposures, however, of the Permian Marl and Lower
Mottled Sandstone, in this area, are in the outliers which occur
west of the Leen. Thus the Marl is seen at Bulwell Quarries,
where it rests with a sharp junction on the Magnesian Limestone,
but appears to pass upwards into Bunter. Farther north, 550
yards south-east of Broomhill, Bunter of very marly character is
seen in a sand-pit, and here an actual lateral passage of marl into
sandrock can be traced. Another small outlier at Butler’s Hill
has been cut through by the Great Northern and Midland Rail-
ways, showing, obscurely, very marly sandrock resting upon a floor
of (Permian) marl.

Details of other sections have been already published,’ and need
not, therefore, be described again.

A curious feature of the Magnesian Limestone, which seems
worthy of more notice than it has yet received,* is the presence of
very sharp anticlinal and monoclinal folds, which form ridges of a
distinctly artificial appearance. Aveline noticed some of them, and
marked them on the Survey map (Old Series) with the anticlinal
symbol. They are, however, fairly numerous, their axes lying
in either a north-westerly or a north-easterly direction; and it
has been found, by examining the colliery plans, that in several
cases the ridge at the surface indicates a fault in the Coal Measures
below. ‘The structure of the ridges may be seen in several quarries
and on the Great Central Railway near Hucknall Torkard, where
the line cuts obliquely through the main ridge. The flaggy lime-
stones, which usually lie almost horizontally, are seen to rise
suddenly into an anticline (or sometimes a monocline) having a dip
of 20°, 40°, or even more. The base of the anticline is often only
some 20 yards wide, and the height of the ridge may be as many
feet. The ridges are not continuous for any distance, but are made
up of elongated domes arranged along a straight line, or sometimes
slightly en échelon. Moreover, mapping has shown that a
fault in the Coal Measures below may extend much farther than

1 BE. Wilson, 1876, p. 534.

2 W. Gibson & others, 1908, ). 109.

3 bid. pp. 106-10 & 129-30; also G. W. Lamplugh & others, 1908, pp. 27-
8 & 3-34.

+ W. Gibson & others, 1908, p. 108.

86 MR. R. L. SHERLOCK ON THE RELATIONSHIP OF THE [ Feb. 1911,

the corresponding surface-ridge, which terminates abruptly. It is
remarkable that these ridges of dolomite are untouched by de-
nudation, and it seems probable that they were formed by
comparatively recent movements along the fault-planes below.
These anticlinal domes will be mentioned again when I deal with
the districts to the north. They are, however, best seen in the
area now descrived, the most important one extending from
Aldercar Wood near Newstead to Bulwell, and forming the boundary
of the Permian Marl in the southern half of its course.

(¢) The Area between the Robin Hood’s Hills
and Mansfield.

North of the Robin Hood’s Hills, the Midland Railway runs
along the low-lying Permian Marl to the outskirts of Mansfield,
and on the rising ground to the east there are several sandpits in
the lower part of the Bunter, which is increasingly argillaceous
towards the bottom. At Kirkby Hardwicke the Permian Marl
has been almost reached, and at East Kirkby a brickyard shows
16 fect of Permian Marl with a sandy band, resting upon a floor of
Magnesian Limestone, and covered by about 6 feet of sandrock
(Bunter).

At Sutton Junction a small north-north-westerly fault has cut off
an outlier of Permian Marl in Sutton-in-Ashfield. The fault is
visible in the Great Northern Railway on the west; while on the
east a sandpit, in the Pebble Beds and Lower Mottled Sandstone,
shows it.

About a mile and a half beyond Sutton Junction the Permian
Marl is cut out by a trough-fault, both arms of which can be seen
in a clay-pit, 400 yards north-east of King’s Mill. ‘The Marl,
however, reappears a quarter of a mile to the east, and can be
followed thence into Mansfield.

Between Mansfield and Skegby there is a large outlier of Permian
Marl and Lower Mottled Sandstone capped by Drift. Along the
southern margin of the outlier a succession of clay-pits display
valuable sections, showing the entire thickness of the Permian Marl
and its junction with the Bunter above and the Limestone below.
The Limestone forms the floors of the clay-pits, and its junction with
the Marl seems always to be a well-defined lithological boundary.
On the other hand, the Marl is succeeded above by marly sandrock
similar to bands occurring within the Marl itself. At first sight,
there seems to be a fairly definite boundary below the sandrock ;
but, on examination, it is seen that this is mainly due to the water
which percolates through the sandrock being thrown out by the
first bed of Marl which it meets—with the result that the Marl
is a little undercut, and the base of the sandrock is bleached to a
pale greenish tint.

Here, again, the boundary between Permian and Bunter is purely
artificial, and has been taken, as before, at the base of the
lowest sandy band of any importance. The Marl, as thus
defined, is fairly constant in thickness (about 15 to 20 feet), but

Vol.67.| PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE, 87

the minor details, such as the position of the sandy bands, vary
within the limits of a single clay-pit.

From Nottingham to Mansfield the Permian Marl has been
followed continuously as a thin bed of silty clay separating the
Bunter from the Magnesian Limestone. At Mansfield, however, the
Mar! has disappeared, and the Bunter rests directly upon the Lime-
stone. ‘This fact, at first sight, seems to offer support to the theory
of an unconformity between the Permian and the Bunter; but a
careful examination of the district offers a different interpretation,
namely, that the Permian Marl has locally changed its character,
and become sandrock indistinguishable from the Bunter above.

The phenomenon of the somewhat sudden disappearance of the

Marl at Mansfield does not stand alone. In the same district the |

Magnesian Limestone, which has also remained fairly constant in
character and thickness from near Nottingham to Sutton-in-
Ashfield, thickens greatly (at Bestwood’ the Magnesian Limestone
is but 30 feet thick, while at Sherwood Colliery, Mansfield, it is
236 feet), and is divisible into different types of rock. The upper
part becomes so sandy, that at Mansfield it forms the well-known
building-stones known as the White and Red Sandstones.
These ‘sandstones’ are really composed of about equal parts of
sand and dolomitic cement,” the red differing from the white merely
in the presence of ferric oxide.
At Messrs. Lindley’s White Sandstone Quarry (south of the eastern
angle of the triangular area marked off by railways on the map)
the Marl above the ‘ sandstone’ is worked for bricks. Near the
western end of the section the Marl is about 18 feet thick, with green
sandy bands; but, as the eastern end of the workings is approached,
the total thickness of the Marl decreases considerably, while a sand-
stone makes its appearance in it and grows rapidly in importance.
Portions of the remaining Marl also become sandy, until at the
eastern extremity of the section it has become :—

Fig. 3.—Section at Messrs. Lindley’s Sandy pebbly soil, and sand,
White Sandstone Quarry, Mansfield. - perhaps slightly slipped

=ac==== Red marl, the lower part sandy

Fine-grained sandrock, leaden-
grey when broken, weathering
MEMO WISH Nistor tos gt canks haan:

Es Marly sandrock (intermediate
[The sandy development of the Lower Mag- in character) ...............0..
nesian Limestone (0) is overlain sharply by'

Permian Middle Marls, in which sandstone Undulating floor of dolomitic
bands (a) develop towards the east (left). ] sandstone (é”),

Thickness in feet.

3

—

1
9°
a

W. Lamplugh & others, 1908, p. 28.
fr.

G.
W. T. Aveline, 1879, pp. 10 & 12.

88 MR. R. L. SHERLOCK ON THE RELATIONSHIP OF THE [ Feb. 1911,

In the Geological Survey Memoir Aveline figures (op. ct. p. 17),
from information received, an unconformable junction otf the
dolomitic sandstone with the red marl.

If the sandy bands in the Marl continued to increase westwards,
it is clear that a sandrock would result, which might be easily
regarded as Bunter; and this would rest directly upon the dolomitic
sandstone with apparent unconformity.

An old pit for potter’s clay, situated close to the railway-bridge
over the Nottingham Road, shows that the Permian Marl still
persists, although the outcrop has become very narrow. At
Littleworth, a section close to the Brewery shows 8 feet of sand-
rock with a 3-inch band of marl very near the Limestone: hence
there is not room for more than a few feet of marl, if any, between
the two. Farther north, sandrock can he seen resting unconformably
upon the dolomitic sandstone below the level of the track of the
Midland Railway, east of Crow Hill (Mansfield); and there is a
good section, showing similar conditions, at Hallam’s Grave, north
of Mansfield.

Origin of the Mansfield Dolomitic Sandstone.

It seems probable that the local great increase of sandiness in
the Magnesian Limestone, and in the Permian Marl above it, have
a common cause. Sedgwick ' inferred that the sandy development
of the limestone is confined to the Mansfield district; but this
statement must be modified slightly, as very sandy limestones occur
in places north of Warsop. However, the fact remains that the
Mansfield Sandstone is almost, if not quite, unique.

On attempting to map the dolomitic sandstone, it is found that, as
it is followed north-eastwards along the strike, it ceases to remain
at the top of the Limestone, but becomes overlain by dolomite, into
which it passes upwards gradually, as, for example, at the Rock
Valley quarries ; and the same conditions are noted if it is followed
north-westwards, across the strike. At the Chesterfield Road
quarry, one mile north-west of Mansfield, and in the very deep old
quarry in Debdale Lane, the ‘sandstone’ is seen at the bottom of
the quarries passing upwards into dolomite. Also at the Chester-
field Road quarry the limestone has been proved underneath the
‘ sandstone,’ which is about 50 feet thick. The sandstone does not
crop out again until Pleasley Vale is reached, when it appears at
the very base of the Magnesian Limestone, with the grey Lower
Marls alone beneath it. It is clear, then, that the sandstone cannot
lie at one horizon, but that it is a lenticular mass tilted in a
direction opposite to the dip of the beds. If the lenticular mass
extends in an easterly, as it does in a westerly, direction, the tilt
will carry the sandy conditions into the Permian Marl; and this at
once explains the apparent absence of the Marl at Mansfield, as it
is there represented by sandy beds which merge into the Bunter
sand above.

1 A. Sedgwick, 1829, pp. 83-84.

Wel. 67. PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 89

Such a mass of sand, surrounded by limestone deposits, can be
explained by supposing it to have been formed as a sandbank at
the mouth of a river, while limestone (or, at a later date, fine silt)
was being deposited on every side. The deposition of the sand
ever farther eastwards as time elapsed indicates a slow rising
of the land, and this might well happen towards the close of the
elevation of the Pennine axis; an elevation generally regarded
as mainly post-Carboniferous and pre-Permian,* but probably not
completed until later.’

The diagram (fig. 4, p. 90) is intended to illustrate the hypothesis,
and also to explain the presence of an outlier of Marlin the western
part of Mansfield, opposite the gap in the main outcrop. It is
supposed that a river flowed south-eastwards from the Pennines and
built up a sand-bar in the shallow Permian sea some miles from
the shore. Limestone was deposited all round the bar on every
side. The slowrise of the sea-floor caused the sandbank to migrate
eastwards to a point where the necessary conditions of depth and
currents existed. As a result, it was deposited on the earlier-
formed limestone, and, at the same time, limestone forming behind
it spread over the earlier sand deposit.

The presence of ripple-marks in the dolomitic sandstone at the
Chesterfield Road quarry, and the footprints of reptiles found in
the Rock Valley quarry, support the view that the rock was
deposited as a Sandbank near the land. Shipman (teste Mr. Hick-
ling *) was also of opinion that the sandstone was formed as a
sandbank. Further support is given to this theory of the re-
placement by sand of the Permian Marl, by the records of Crown
Farm Colliery, situated on Bunter Pebble Beds, a mile and a half
east of Rock Valley. Here, under 112 feet of Lower Mottled Sand-
stone, 16 feet of marly beds were met with resting upon limestone,
proving that the normal amount of Permian Mar] is here present.

The reptilian footprints, and the slight unconformity of the rocks
above, show that the sandbank reached the surface at the close of
the Magnesian Limestone period. After an interval, a slight
subsidence allowed the sandbank to be formed again ; but now marl,
instead of limestone, was deposited round it.

To make this clearer, fig. 5 (p. 90) is appended. Here a, b, ¢
represent the successive positions of the sea-level, and a’, b', c’ the
sand-bars formed at the corresponding times. The contemporary
deposits of limestone are represented by the letters a,, b,,¢,. The
convergence of the lines a, b, ¢ represents the eastward tilting of the
sea-floor.

The deposition of limestone on all sides of the sand-bar offers a
difficulty, but the difficulty is not due to the sand-bar theory, for
the fact remains that sandstone and limestone can be, and were,
deposited in contact and passing one into the other. The mode
of origin of the limestone is not understood, except that it is a
} J. J. H. Teall, 1880, p. 92; E. Wilson, 1880, pv. 93.

2 Pp. F. Kendall, 1902, pp. 510-13.
3 G. Hickling, 1906, p. 125.

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Vol.67.] THE PERMIAN AND TRIAS OF NOTTINGHAMSHIRE. 91

shallow-water formation, as is shown by its frequent cross-
bedding, the presence of sand-grains, and the breccia into which
it passes at Nottingham. Sorby (1879, p. 85) considered it to have
been formed partly by precipitation and partly from organic débris ;
but it may be, in part at least, of detrital origin and formed from
the denudation of the Carboniferous Limestone of the Pennines.

Rock-specimens were collected from points along the line of
section of fig. 4 for microscopic examination, namely: (1) from
Baxter Hill, overlooking Pleasley Vale; (2) from the ‘Red Sand-
stone’ of Mansfield ; (3) from the sandrock in the Permian Marl
above the ‘ White Sandstone,’ at Messrs. Lindley’s quarry ; and
(4) from -a gritty band in the Lower Mottled Sandstone, at the
quarry of the Mansfield Sand Co., Ltd., south-east of the town.
The first three differed from the fourth in being dolomitic, but the
insoluble residues were all of the same character. The bulk of
each residue consisted of quartz-sand, the grains differing somewhat
in size in the different specimens, the larger being the more
rounded. In addition, the residues contained more or less chert,
felspar, and quartzite. These latter constituents are interesting,
as their presence was to be expected in sediment derived from
the Carboniferous limestones and grits of the Pennines. A speci-
men taken from near the top of the Pebble Beds, in the railway-
cutting between Daybrook and Nottingham, may be mentioned
here for comparison. The insoluble residue consisted of coarse
quartz-sand with felspar, and a few small grains which are probably
chert.

The large outlier between Mansfield and Skegby has been
mentioned above (p. 86), but nothing was said of the evidence which
it affords of a lateral passage of Permian Marl into sandrock.
From Skegby, as far eastwards as Hight Men’s Intake, the Permian
Marl maintains its normal character and thickness; but, as we
trace it still farther eastwards, itis seen to become much more silty,
and, at the large clay-pit of the Mansfield Stone & Brick Works,
300 yards south-east of Eight Men’s Intake, it is intermediate in
character between Permian Marl and Bunter—in fact, it resembles
closely the passage-bed seen in the Great Central Railway, already
described. The section being an important one, details are given
here :——

Thickness in feet inches.

SOTA ius vhicane st cene (aso are ee Ae te geec ck <a vin eines eos os 2 0
Red marl with ENREID DIRE IES ee ge Ae a eee 1 6
Red marly sandstone seamed with mar]; green streaks... 1 6
Red marl with ereem streaks, ...42-...iiccsideetes doctsesb eves 1 6
Hard red: marly Gamdstoney. cis...) ,2sncerascacenstecscnbsdncs | 3

Do. do. with green streaks ............ 1 iW)
Fue Gitar i Ba octane eres eats Set as ce ate co fcuspiailea > sap 0 +
Red tine-Praimed SaMGstOne- a. shc2.cc..-cee-satedeess-.cerceee 1 1

a
oO
Qu
5
2
=
—_
:
—
~
-—

92 MR. R, L. SHERLOCK ON THE RELATIONSHIP OF THE [ Feb. 1911,

The floor is a hard sandstone about 3 feet thick, which has been
broken into 150 yards away to the south-east, and is seen to rest upon
a somewhat uneven surface of the dolomitic sandstone (Magnesian
Limestone). The junction is less marked than usual, owing to
both formations being sandy.

To sum up, the sections in the Mansfield district show
a lateral passage of ‘Permian Marl’ into Bunter, as
distinctly as the Great Central Railway cuttings,
previously described, showed an upward passage.

An unusual feature of the Bunter in the Mansfield district, which

Fig. 6.—The sundptt of the Mansfield Sand Company, Ltd.,
Berryhill, Mansfield.

= ——— SS

2 suerte soe SS = SS Pe =
5 = SSS oe eS ~e—e 3, :
: Fb, gS ee ee EES: 2's,
Z Ya Oy tye ee SEES a eee ;
Gi - ees eA Fn nae ae
ee ye BE Ips ode Zi SS DO gor 5S. Sopa 3
AeA Ui Soph pte irs %: %Y )

[The sharp line marks the unconformable junction of the Pebble Beds with
the underlying Lower Mottled Sandstone. The line is more evident on
the left, where the rock has been newly excavated. |

may be mentioned here, is the presence of a marked unconformity
between the Pebble Beds and the Lower Mottled Sandstone. This is
very clearly seen in the huge sand-pit of the Mansfield Sand Co., Ltd.,
south-east of the town (see fig. 6, above). Here a vertical section,
of about 75 feet in all, shows some 45 feet of coarse pink sandrock
with occasional pebbles, which are more numerous towards the
top, resting on about 30 feet of soft red marly sandrock, quite
free from pebbles, but with bands of grit in the lower part. The

Vol. 67.] PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 93

unconformity between the two is a striking one, and pebbles of
the eroded Lower Mottled can be found in the Pebble Beds above.
The unconformity disappears within a mile on either side of the
sand-pit. It seems probable that such a local break would be
more likely to occur during deposition at the mouth of a river,
rather than elsewhere.

(f) The Area between Mansfield and Warsop.

Proceeding northwards from Mansfield, although the base of the
Lower Mottled Sandstone is seen to contain many lenticles of Marl,
there is no appearance of a distinct band of marl between the Lime-
stone and the Bunter until Mansfield Woodhouse is reached, Here,
however, the Marl reappears, and has been traced as far north as
Warsop Station, at which point the 6-inch mapping terminated.
A large outlier of Marl, not previously known, exists at Park Hall
and Nettleworth Manor.

Before leaving this district, mention must be made of the
characters of the Magnesian Limestone. To the north of Sutton-
in-Ashfield (as has been already stated) the Limestone increases
greatly in thickness, and becomes very variable in composition.
The famous dolomite which was used in the foundations of the
Houses of Parliament is said to have been quarried at Mansfield
Woodhouse. Here it occurs as domes, which form hills, rising like
islands from the surrounding flat of normal, flaggy, coarse-grained
dolomite. The building-stone is a creamy dolomite of fine texture,
without any trace of bedding. The mass is divided up into short
thick lenticles, by planes which have no special orientation. A
further remarkable feature is the presence of cylindrical cavities
known as ‘ gulls, which may have a diameter of over an inch with
a length of several feet, and lie in any direction. They bear a
curious resemblance to the holes made by a crowbar for blasting,
and, in fact, when their direction happens to be suitable, they are
utilized for the purpose. The appearance of the rock suggests
swelling as the result of chemical changes. Although the actual
junction of the two varieties of dolomite is not visible, they may be
seen in quarries within about 200 yards of one another; and it is
noticeable that the normal flaggy type shows no sign of an on-
coming change, nor is its low dip disturbed.

(2) North Nottinghamshire.

I have not been able to continue the detailed mapping beyond
Warsop Station, but the Permian outcrop has been followed along
its entire length to its termination in Northumberland, special
attention being paid to published sections.

At Warsop, superficial deposits mark the junction of the Permian
with the Bunter, and the presence or absence of the Permian Marl
can only be inferred. However, a section, described and figured by

94 MR. R. L. SHERLOCK ON THE RELATIONSHIP OF THE [Feb. 1911,

Fox-Strangways,’ at Warsop Colliery Junction, on the Lancashire,
Derbyshire, & East Coast Railway, to some extent fills this
gap. The Magnesian Limestone was seen to be arched into an
anticline, and covered by horizontal Permian Marl and thin flagey
limestones which merged laterally into marl. These thin limestone-
bands appear to be ‘ skerries ’"— that is, the equivalents of the sand-
stone bands which, occur in the Marl in the country to the south.
Just as the sandstone bands increase in importance towards the
top of the Marl, until they replace it altogether and give rise to
the Bunter, so here it may be that the thin limestones mark the
incoming of the Upper Magnesian Limestone which overlies the
Marl farther north.

Mr. Bernard Smith informs me that he has found bands of
almost pure dolomite interbedded with the Keuper Waterstones at
several places, and especially at Westhorpe, near Southwell.
These dolomite bands occur in exactly the same manner as the
sandstone bands, which are themselves dolomitic. This is a good
illustration of how a limestone band such as the Upper Limestone
may have been formed contemporaneously with the sandstone of
an adjacent area.

Although where the junction of the Lower Limestone and
Permian Mar] is seen, south of Warsop, it is an abrupt one and is
sometimes an unconformity, Mr. J. B. Hill* has noticed a passage
between the two in the Shirebrook district.

At Cuckney, where the Permian Mar! can again be recognized, the
Survey map represents it as having a wide outcrop; and on it,
at Collingthwaite, is mapped an outlier of the Upper Magnesian
Limestone, the southernmost appearance of this member of the
series. The outlier is now represented by fragments of weathered
limestone lying on the ploughed fields at the top of a hill, and
Aveline himself does not seem to have seen more than this. His
own account is as follows * :—

‘On the larger of the two outliers the limestone has been quarried. This
quarry has been filled up, but the fragments of the stone are strewn plentifully
over the field. It is a fine and close-grained stone, of a yellow colour, aud it
appears from the fragments to be stratified in thin flag-like beds. No fossils
were seen in these scattered fragments, though they occur plentitully in the
equivalent beds in the north. The existence of the smaller outlier is only
indicated by the loose stones lying on the field.’

The second outlier here mentioned is situated about half-a-mile
to the north-west of the larger one. The road to Holbeck Wood-
house, immediately under the hill capped by the smaller outlier,
shows a good section, in sandrock, which presents precisely the
appearance of typical Lower Mottled Sandstone. Aveline,* who
refers it to the ‘ Permian Red Marl and Sandstone’ (that is, the

1 ©. Fox-Strangways, 1898, p. 160.

2 «Summary of Progress for 1908’ Mem, Geol. Surv. 1909, p. 18.
3 W. T. Aveline, 1879, pp. 18-19.

4 Ibid. p. 18.

Vol. 67.] PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 95

‘Permian Middle Marl’ of adjacent maps) underlying the Upper
Magnesian Limestone, says :—

‘ A good section of these sandstones may be seen in a lane between Wood-
house Hill Farm and Holbeck Woodhouse. Here there are between thirty
and forty feet of soft red sandstone in thick beds, except about six feet at the
centre, which consists of thin alternations of sandstone and marl. Another
section may be seen in a road-cutting about ten chains to the south-east of
Woodhouse Hill Farm, consisting of unconsolidated red sand containing a few
pebbles, and interstratified with thin beds of more consolidated sand. The
thickness of the sand is from twelve to fifteen feet.’

The presence of pebbles is of interest, as they are quite absent in
the Permian Marl between Nottingham and Warsop, but are not
uncommon in breccia-bards in the Lower Mottled Sandstone. Under
the microscope the sand is seen to be quite similar to that from
the Iower Mottled Sandstone of Mansfield (see p. 91). If the
sandstone seen in the road-cuttings is regarded as Bunter, the
limestone becomes a local lenticle in it—quite comparable to
that noticed by Fox-Strangways at Warsop Vale, in the Permian
Marl, or to one of the ‘skerries’ in the same marl at many places
farther south. Moreover, the sudden expansion of the Permian
Marl outcrop coinciding with its change in lithological character,
so greatly at variance with the uniform character of the bed between
Cuckney and its termination at Nottingham, is at once explained
if the upper part of the ‘ Marl’ is regarded as Lower Mottled.

Of the beds between the Lower and the Upper Magnesian
Limestone in the district between Welbeck and Tickhill (Sheet 82,
N.E.), which have again changed their name and are now called
the Middle Marls and Sandstones, Aveline * says :—

‘ These beds, consisting of red marls and soft sandstones of various colours
sometimes containing small pebbles, divide the Lower from the Upper
Magnesian Limestone. They lie somewhat unconformably on the former, and
there is no good section in this district showing a passage upwards into the
latter.... At Ratcliff there are beds of red sandstone, which might easily
be mistaken for the New Red mottled sandstone of the neighbouring districts
if it were not that the strata at Ratcliff are overlaid by red marl; whereas ie
red and mottled sandstone of the Bunter beds is always overlaid by the
Pebble Beds.’

The outcrop of these Marls and Sandstones is very variable in
width, and at Letwell, where the Upper Limestone outcrop widens
greatly, it becomes proportionately narrow. Aveline? remarks that
here the thickness has diminished to 20 feet, as compared with
more than twice that thickness at Shireoaks.

Here it is to be noticed (1) that the Middle Marls and Sand-
stones are unconformable to the beds below, as we have seen to be
the case elsewhere ; (2) that the sudden increase in width of the
Upper Limestone outcrop coincides with a marked diminution of
the Marls and Sandstones, as if they were replaced by it; and (3)
that the Ratcliff beds would have been called Bunter, if sand-
stone, instead of marl, had been found above them.

* W. T. Aveline, 1880 (No. 2) p. 18.
2 Ibid. p. 19.

96 MR. R. L. SHERLOCK ON THE RELATIONSHIP OF THE [Feb. 1911,

Above the Upper Limestone another division of the Permian,
the Upper Marl (e’), is recognized at two places (north of Carlton
and at Whin Common). ‘These occurrences are mapped as lenticles,
and there does not seem to be any reason why they should be
regarded as Permian rather than Trias, especially as such lenticles
of marl do occur in the Bunter, even high up in the Pebble Beds (as,
for example, at Blidworth, east of Mansfield). The late Mr. Fox-
Strangways informed me that he considered these Upper Marls to
belong to the Bunter.

In the north of Nottinghamshire the Lower Mottled Sandstone
ceases to be traceable as a separate formation. A road-cutting at
Spittal Hill, about a mile east of Tickhill, shows red sandstone of a
character intermediate between the typical Lower Mottled Sand-
stone and the Pebble Beds. It is coloured on the Geological Survey
map as Lower Mottled; but the outcrop is marked as very narrow,
and is not continued beyond the latitude of Doncaster.

(3) Yorkshire.

North of Tickhill superficial deposits hide the upper limit of the
Upper Limestone, and often the lower divisions of the Permian
also.

During the cutting of the new South Yorkshire Junction
Railway, a temporary section was exposed at Wadworth Carr,
about 5 miles south-south-east of Doncaster. Mr. H. Culpin,
who drew my attention to the section, informs me that he saw
here Triassic sandy strata resting unconformably on the Upper
Permian Marl.

It may be that here a local unconformity occurs between the
Upper Permian Marl and the Bunter, similar to that already
described between the Lower Mottled Sandstone and the Pebble
Beds at Mansfield. It is, however, a striking coincidence that
the section is precisely on the line of the Kdlington Wood fault
(see Geol. Surv. map, Sheet 87, 8.E.). In these soft strata a fault
sometimes bears a close resemblance to an unconformity, and a
change in the direction of throw in the Permian (which would
apparently be necessary on this explanation) is not uncommon.
Instances occur at Skegby and Newbound Mill, where faults proved -
in the Coal Measures are directly in line with faults throwing in
the opposite direction in the Permian. ‘The curious phenomenon of
the reversal of the direction of throw of a fault seems to be due to
a post-Carboniferous but pre-Permian movement being followed by
a slight post-Permian movement in the opposite direction. It
may be that the second movement is due to a small recovery of
the strata during the period of rest following the upheaval of the
Pennine Chain—in fact, a movement of the kind classified by
Chamberlin & Salisbury under ‘Mutual Adjustment of Conti-
nental & Oceanic Segments.’! Whatever may be the explanation,

1 T. C. Chamberlin & R. D. Salisbury, vol. 11 (1906) p. 236.

Vol:-67.| PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 97

however, a difference in the direction of throw in a fault in the
Carboniferous and Permian rocks is clearly proved in the Annesley
district and elsewhere.

The Wadworth section has been entirely destroyed, but a new
one has been opened (August 1909) at a lower level, and this
shows the presence of an elongated dome of flaggy limestone below
the Marl. The limestone, of which about 10 feet was seen, could
be easily matched in the Lower Magnesian Limestone of the
Mansfield district. The presence of the anticline, in which the
strata have a dip of about 10°, and which is quite similar to those
described above as occurring near Hucknall Torkard over Coal-
Measure faults, is a further indication that the strata here may
be disturbed by the Edlington-Wood fault.

Geological Survey Memoirs have not been issued for the district
between Tickhill and Pontefract, although there are notices of the
Permian rocks in the Memoir on the Yorkshire Coalfield, and a
brief note on the Permian of Pontefract, in the Explanation of
Quarter-Sheet 87 N.W.,’ which do not bear on the present question.
Near Tadcaster, however, the Survey Memoir (W. T. Avcline &
others, 1870, pp. 9, 10) states that the Middle Marl consists

‘of red or variegated marls, with beds of soft sandstone sometimes, and in
some parts of its range gypsum..... The thickness of the Middle Marl varies
considerably ; it is sometimes absent altogether, and it is probable that it was
very irregularly deposited ; the greatest thickness in this district is somewhere
about 50 feet..... The Upper Limestone differs considerably from the Lower
Limestone, being generally harder, thinly bedded, and full of fossils. It con-
tains little or no magnesia... .. [The Upper Red Marl (e’)] is probably a very
thin irregular deposit. It is precisely similar in its lithological character to
the Middle Marl.’

Minor unconformities are stated to occur between different
members of the Permian formation here. The most important is
in the railway-cutting near Tadcaster, where the

*Middle Marl has there thinned away to a mere seam, so that the Upper
Limestone rests almost directly on the Lower, and at the base of the former
there is a thin bed of gravel formed of Lower Limestone pebbles.’

In the Harrogate district Fox-Strangways’ noted that at the
bottom of the system occurs a Lower Marl and Sands very like
the Bunter Sandstone, but with thin seams of unctuous white clay,
followed by quicksand. Above is the Lower Magnesian Limestone,
175 feet thick. The Middle Marl follows, and is composed
of red marls and soft red sandstone, sometimes very like that of
Triassic age. The Upper Marl is not known in the district, but
the Bunter is represented by ‘a soft, brick-red, thick-bedded sand-
stone, containing occasionally thin marly partings.’

North of this district no information bearing on the present
question is to be obtained from the Geological Survey Memoirs.

' A. H. Green & R. Russell, 1879, p. 11.
2 C. Fox-Strangways, 1908, p. 11.
G. J. G. S.No. 265; H

98 MR. R. L, SHERLOCK ON THE RELATIONSHIP OF THE [Feb. 1g11,

A good general account of the Yorkshire Permian was given
by Wilson,’ who classified the beds as follows :—

Upper Marls. 50 feet. A maximum.

Upper Limestone = Brotherton Beds. 30-120 feet.

Middle Marls. 50-380 feet or less.

Small-grained Dolomite, about 200 feet.
Lower Limestone, about 120 feet.
Quicksands, Marl Slates, and basal breccia, local and variable.

Lower Magnesian Limestone. {

The Small-grained Dolomite would seem to be the representative
of the limestone which forms the knolls of Mansfield Woodhouse.
The Lower Limestone is stated to be either thickly or thinly bedded,
oolitic or crystalline, with thin marly partings and occasionally
ripple-marks. Kirkby ’ gives a list of 31 species of fossils obtained
from it in South Yorkshire: of these it has eleven species in
common with the Compact Limestone of Durham (lowest division) ;
but 29 species occur also in the Middle (Shell) Limestone of
Durham. The Small-grained Dolomite is practically unfossili-
ferous. The Middle Marls are very variable in thickness.
Sedgwick® states that they are absent north of the Wharfe; and
south of that river also they are sometimes absent (as, for example
Tadcaster).

The Upper Limestone (or Brotherton Beds) comprises thinly-
bedded, white or grey, red or yellow strata, with little or no
magnesia. They exhibit marly partings, ripple-marks, and sun-
cracks. The fossils are of very few species.

The Trias of Yorkshire is divided into two broad divisions *:
an upper, consisting almost exclusively of marls with gypsum;
and a lower, more variable division, in which sandstone greatly
predominates. These divisions correspond broadly with the
Keuper and the Bunter.

The Bunter is not capable of subdivision, even in the south of
Yorkshire; and north of Ripon it cannot be separated at all from
the rest of the Trias. Deep borings have increased rather than
diminished the confusion, for Keuper characteristics may occur in
rocks which, from their position, ought to be Bunter. Prof. Kendall
remarks that the most that it is prudent to assert is, that Keuper
characteristics are more frequent at the top of the sandstone series,,
while those elsewhere diagnostic of Bunter prevail more near the
base.

1 E. Wilson, 1881, p. 189.

2 J. W. Kirkby, 1861, p. 310.

3 A. Sedgwick, 1829, p. 103.

4 P. F. Kendall, ‘ Geology’ in the ‘ Victoria County History of Yorkshire:
1908, p. 5 (reprint).

Vol. 67. ] PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 99

(4) Durham County.

Prof. Lebour’ has recently classified the Permian and Trias in

this county as follows :—

(Quicksands).

or less incoherent, water-
bearing sandstone.

Period. Formation. Character of Material. ee
Keuper RedSandstones Mostly red rocks with deposits
Satur MEAsurEs and Marls passing of rock-salt, gypsum, an- te 66
(Trias above, downwards into si- hydrite, and thin magnesian iG
Upper Permian below). milar Permian Sand- limestones towards the
stones, etc. base.
( Magnesian Limestone. Often concretionary. up to 800
Mar] Slate. Flagg y calcareous beds: fish- up to 15
7 remains. (usually 3)
FPN, Yellow Sands Generally yellow, but some-
times dark-coloured, more yp to 104

He remarks that the subdivision of the limestone is difficult, and
that the following scheme drawn up by the late R. Howse is only
tentative, although the best available up to the present :—

(f) Upper yellow limestone and
(é) botryoidal limestone.

(d) Cellular limestone and

(c) shell limestone.

(6) Compact limestone and

(a) a conglomerate at the base.

\ Upper Grovp (8).
} MippLez Grove (2).

\ Lowrr Grovr (1).

Here the Middle Marls of South Yorkshire have disappeared,
and are presumably represented by limestone.

The Upper Group of Durham is lithologically very remarkable,
and contains the well-known concretionary limestone of the Durham
cliffs,? which cannot be matched in Yorkshire.

The thickness of the Magnesian Limestone Series varies from
800 to as little as 299 feet at Whitehouse, Norton, and even this
small thickness contains shale, gypsum, and nearly 90 feet of
anhydrite.”

In Northumberland only the lower divisions of the Zechstein
are present.

The Salt Measures above the Limestone are of great interest,
and there has been much discussion as to their age. According to
the Geological Survey map, the Magnesian Limestone is imme-
diately overlain by Keuper Waterstones; Prof. Hull* thinks that
the salt-rock proved in the Middlesbrough boring occupies the
geological position of that which occurs in Cheshire, Staffordshire,

1G. A. Lebour, ‘ Geology’ in the ‘ Victoria County History of Durham’ p. 2
(reprint).
2 E. J. Garwood, 1891.
3 T. Tate, 1892, p. 493.
4 E. Hull, in Bell, 1887, p. 155.
H 2

100 MR. RB. L. SHERLOCK ON THE RELATIONSHIP OF THE [ Feb. IgI1I,

etc. (that is, it is of Keuper age). The late C. E. de Rance thought
(Rep. Brit. Assoc. 1885, p. 384) that |

‘the pebbly character of the middle portion of the Bunter has died away
northwards, and that the Middlesbrough section represents Waterstones,
pebbleless Middle Bunter, and Lower Bunter.’

Prof. Lebour’s view is indicated by the classification tabulated
on the preceding page.

Dr. Woolacott* has recently suggested a new classification of the
Permian of the North-East of England, which places 300 feet of
the Salt Measures in the Permian, and to this portion he gives the
name of ‘ Middlesbrough Red Beds with Salt.’

Sir Andrew Ramsay,’ referring in 1880 to Messrs. Bell Brothers’
trial-boring at Saltholme, stated that 1175 feet of red sandstones
and marls, with beds of rock-salt and gypsum, were passed through.
These strata he considered to be Keuper Marls and sandstones.
Beneath these came 67 feet of dolomitic limestone, which, he said,
in this neighbourhood forms the upper part of the Permian Series;
and beneath the limestone the strata consist of 27 feet of gypsum,
rock-salt, and marls, one of the beds of rock-salt having a thick-
ness of 14 feet. Wilson? described the 67 feet of dolomitic lime-
stone as ‘indurated marls,’ and averred that they did not resemble
any known beds of the Magnesian Limestone of Durham, but had
the greenish-grey colour of certain Keuper Marls: therefore, he
referred the whole of the strata passed through in this boring to
the Keuper. Wilson thought it most improbable that the upper
part of the boring was in Keuper and the lower part in Permian,
because of the unlikelihood of an uncommon mineral, such as rock-
salt, occurring at two horizons, within 200 feet. of one another
in the same vertical section, in two distinct rock-series. He added
that the chances against such a coincidence are vastly increased,
when we consider that there is no sort of sequence between the two
formations in the district in question, but that, on the contrary,
there is a decided break and unconformity between them—indicated
by the omission of the whole of the Bunter and Muschelkalk. He
also remarked that this discordance between Permian and Trias
in Durham is probably, in large measure, due to want of conformity
between the Keuper and the Bunter, coupled also perhaps with an
original northward thinning-out of the Bunter Sandstone.

Mr. H. H. Howell, in 1890, gave his reasons for recommending
that all the red rocks, between the Rhetic and the Durham
Permian limestones, should be classified as Keuper on the Geological
Survey maps. He states that he has examined the rocks which
underlie the undoubted Keuper at the few places where they crop
out from under the Drift, and that they have a distinctly Keuperian
aspect and are not in the least like Bunter. The cores of borings

' D. Woolacott, Rep. Brit. Assoc. 1909. 2 A. C. Ramsay, 1880, p. 11.
3 KE. Wilson, 1888, p. 771.

Vol. 67. ] PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 101

confirmed him in this opinion: he found no trace of a break
or unconformity within the red rocks—they seemed due to one
continuous deposition—and he felt compelled to carry down the
base-line of the Keuper to an horizon where the lithological
characters were marked and distinct, namely, to the junction with
the Durham Permian Limestone. At this horizon there is some
evidence of a possible unconformity. At Seaton Carew the red
rocks rest upon the upper division of the Limestone, which crops
out at Hartlepool. A boring on the north side of the Tees yielded
Axinus dubius and a roestone bed similar to one in the cliffs at
Hartlepool, indicating that the red rocks rest upon the same horizon
of the Limestone as at Seaton Carew. But, at the western outcrop
of the red rocks near Darlington, Leeming Lane, and Ripon they
rest (with a thick bed of gypsum at the base) upon the fossiliferous
and compact limestone of the Durham Permian—that division
which immediately overlies the Marl Slate. Mr. Howell objected
to Wilson’s description of the limestone at Saltholme as ‘ indurated
marl, and gave an analysis showing that it contains over 95 per
cent. of carbonates of calclum and magnesium. He also quoted
Howse’s view that this limestone and the accompanying marl are
identical with the Upper Limestone and Red Marl of Sedgwick,
and the Brotherton Beds and Red Marl of Kirkby, as exposed at
Brotherton and other localities in South Yorkshire.

Many other borings have been put down in the Durham salt-
district, which for the most part pass through strata similar to those
at Saltholme*; but the only one requiring mention here is that at
Seaton Carew, mentioned above, which was made by Messrs. Case-
bourne & Co. in 1887. Rock-salt was not met with in this case; but
the boring was continued into the Carboniferous, and proved that
the Magnesian Limestone was 878 feet thick.

It appears from the conflicting evidence just adduced that nothing
is certainly known as to the age of the Salt Measures. The uncon-
formities which different geologists would place at different horizons
of the strata passed through by the boring seem to be fixed on purely
hypothetical grounds, except the one at the top of the Durham
Permian Limestone. That there is an unconformity in some parts
of England between the Keuper and the Bunter is probable, and in
fact detailed mapping indicates that this is the case near Nottingham.
The unconformity is, however, often assumed, in order to account
for the apparent absence of the Muschelkalk; and it is far from
certain that this formation is not represented in parts of England
by sediments. Mr. Woodward’ thinks that this is the case in
Devon, and, recently, Mr. Wills*® has shown that certain beds which
have the appearance of Lower Keuper are not improbably of Letten-
kohle, or Muschelkalk, age.

+ EH. Wilson, 1888, p. 765.
2 H. B. Woodward, 1874, p. 389.
3 L. J. Wills, 1910, p. 268.

102 MR. RB. L. SHERLOCK ON THE RELATIONSHIP OF THE [Feb. 1911,

(5) The Evidence from Deep Borings.

In addition to the deep borings in the Middlesbrough district,
mentioned for convenience in the last section, a number of borings
have been made in search of coal or water through the New Red
rocks farther south.

In most cases, when boring through New Red rocks, it is im-
possible to say at what depth a particular division was met with, so
that the thicknesses given generally are merely approximate. No
boundary-line, for example, can be drawn between Pebble Beds and
Lower Mottled Sandstone; and often the junction of the Bunter with
the Keuper and the Permian would be taken at different horizons
by different authorities. Making allowance for this difficulty, how-
ever, the borings are of great interest, since they enable us to trace
the Permian deposits away from the Permian coast-line into what
was presumably deeper water.

At Gedling Colliery * (situated about 3 miles north-east of Not-
tingham Market Place) the Bunter is 385 feet thick, and the Permian
consists of 46 feet of grey shales with 8 inches of basal breccia.

At Thurgarton boring, 6 miles to the north-east of Gedling, the
Bunter was 494 feet and the Permian was about 93 feet thick.
The latter consisted of red and blue shales with sandstone bands,
a thin seam of gypsum, and a basal breccia. Possibly these beds
represent the Marl Slates, Limestone, and Middle Marl. The
absence of limestone at Gedling and Thurgarton is remarkable.

At Bestwood Colliery, 5 miles north-north-west of Nottingham,
the shaft was commenced in Bunter, and passed through 19 feet of
the Middle Marls and 30 feet of Limestone into Coal Measures.

At the Oxton coal-boring, 5 miles north-east of Nottingham,
below 374 feet of Bunter Sandstone, there was 9 feet of ‘ Permian
Marl,’ Limestone 45 feet, Marl Slate 85 feet,and Basal Breccia 23 feet.

At the Crown-Farm’ Colliery, Mansfield, where the shaft was
commenced in Bunter Pebble Beds, the Lower Mottled Sandstone
was 112 feet thick, and was followed by 16 feet of Marl with
micaceous sandy bands, then Limestone 67 feet, Marl Slate 98 feet,
and Breccia 3 feet.

At Southear ’ (also known as Sheep ) the New Red consisted of

Thickness in feet inches.

Upper Keuper (incomplete) .............c....0008- 1057) ae
TO Wee GUI eI Geren eee Get ciart «<u « Ree eee 008 eat
BS TO :(6) Ges ee ots Ne cae RRs 9 Oo 434 4
( U Marls (with PyPSUI) .,.. emeeeeeee eee 7 0
Mavis. | Asie Bee ih coc. REE 8) : £6
| arls and sandstones (with gypsum). 73 i
Upper Magnesian Limestone ..................48 53 0
Permian. { Middle Marls (with gypsum) ............-........ 132 9
roe Magnesian Limestone, with a
‘as little marl and gypsum near
| dee the top and 15 feet of shale at ato :

Vieabaiematet secs. . ooeeemeaeihins ;
Coat MEASURES.

1 W. Gibson, in ‘The Geology of the Country between Newark & Notting-
‘ham’ 1908, pp. 13-17. 2 G. Dunston, 1896-97, p. 522.

‘
Vol. 67.] PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 103
The boring at Barlow, near Selby, is also an important one.

The following section is taken from Mr. Durnford’s paper, where
full details are given (1907-1908, p. 437) :—

Thickness in feet.
ATV iii See Be ay coche kh insist aeack eoskbnas 94
Sandstone with occasional marl bands............... 611
Red and aig@ttleds Mielec cli ibe. ales eek eke. 39
Gry PSU SHGvapOR Its e225. e526 oc eksc sek te ee eee 20
Red marl with eypsain) 2. ...15 55 cec.cs esses dasetd sewn 26
Mapnesian. Tam@siane. i orcsccic socssec ove nacune.sacesets 103
Red marl (with limestone layers) ..................... 64
Book-salt: ., <span onisaisvocs cies senondecoses 20
Limestone (with layers of anhydrite and marl)... 317

Coal Measures.

Mr. Durnford thinks that the highest bed of anhydrite is that
which occurs at Southcar. Whether the beds above are of Keuper
or of Bunter age is a matter of controversy.

(6) Cumberland and Westmorland.

Strata belonging to the Upper Permian formation occur in the
Eden Valley and at St. Bees Head, and there are also a few small
patches south of the Lake District.

' According to Goodchild (1891-92, pp. 22-24), the succession in
Cumberland and Westmorland is as follows :—

Maximum thickness
B,. Upper New Red. in feet.

5. Keuper Marls. Red marls with rock-salt, gypsum,
subordinate flagstones, and, near the base, thin beds
gp Maonesian Wiieemaes aes ccoe sce fedencese vec stes sone ?+950

4. St. Bees and Kirklinton Sandstones. Mainly of a
Venetian-red colour, with subordinate strata of red
sandy shale or marl. The series may be divided
into :—

(iv) An uppermost band of cellular rock (Water-
stones).

(iii) Zone characterized by tile-red colours (Kirk-
linton Sandstone).

(ii) Venetian-red sandstones, with occasional white
bands and a local development of fine
conglomerate (Pebble Beds).

(i) Variegated zones (Lower Mottled) graduating
into the next subdivision............... Total 2000

3. Gypsiferous Marls (Bunter Marls); chocolate and Vene-
tian-red shales, with subordinate micaceous flags,
large segregations of gypsum at various horizons. A
band of conglomerate occurs locally at the base,
which reposes discordantly upon various members

Gt (2) and (1) -.SeReMemncen A oe hee ois ovis, sas ccwaessceasees 300

7

104 MR. R, L. SHERLOCK ON THE RELATIONSHIP OF THE [Feb. 1911,

[Cumberland & Westmorland succession. | Maxim dees
B,. Magnesian Limestone Series. in feet.
2i1, Magnesian Limestone. Impure cellular dolomite ... 0 to 10

2), Plant Beds (Marl Slate). Alternations of dolomitic
sandstones with thin bands of impure dolomite, clays
and shales, bands of lignite, and occasional thin coals.
Remains of Neggerathia, Walchia, Ulimannia, and
bracts of cones. In the Helton Section these beds
may We? 2. ae eee RRR RR ernie cis eis s dare San ee Ree 150
B,. Lower New Red or Roth-todt-liegende.

liv, Copper-red sandstones, usually devoid of mica and
generally containing much secondary quartz. Exhibit
footprints.

iii, Upper Brockram ; breccias of angular fragments of
Carboniferous rocks.

lii, Penrith Sandstone as 1’, but much more false-bedded,
and usually coarser (unfossiliferous).

li. Lower Brockram, as liv [? Jiii], The maximum
thickness near Appleby may be 1500 feet, but its
extreme variability and excessive false-bedding
render any exact estimate almost impossible ? 1500

On the north-east side of St. Bees Head there is a well-known
section, showing Magnesian Limestone (2" in the foregoing table)
with casts of fossils, resting on 3 feet of breccia, which overlies un-
conformably Carboniferous sandstones. Above the limestone there
is some 30 feet of red marl, succeeded by a 15-foot bed of gypsum,
which was mined until recently. A second bed of gypsum succeeds
this, separated by 2 or 3 feet of marl; and, still higher, there is
an alternation of red marl and fine-grained sandstone-bands with
flakes of mica. These strata are very like the passage-beds between
the Permian Marl and the Bunter seen in Nottinghamshire, and
like them they pass up into sandstone, in this case the St. Bees
Sandstone.

Sedgwick,’ who first described this section, considered the
St. Bees Sandstone to be of Bunter age, and, seeing no break in the
succession, named everything above the Magnesian Limestone, Trias.
Later, in 1864, Murchison & Harkness, recognizing the gypsiferous
marls above the limestone as the equivalent of Murchison’s Upper
Permian (Bunterschiefer), were for the same reason obliged to assign
the whole of the St. Bees Sandstone to the Permian: for it was con-
sidered, at that time, that there must be an unconformity between
the Permian and the Trias.

Mr. T. V. Holmes (1881) agreed with Murchison in referring the
whole mass to the Permian ; whereas Goodchild followed Sedgwick,
and made everything above the limestone Trias. Dr. Irving * also
holds that the St. Bees Sandstone is of Bunter age.

Mr. Holmes regards the Kirklinton Sandstone as Lower Keuper

1 A. Sedgwick, 1836, p. 598.
2 A. Irving, 1882, p. 163.

Vol. 67.] | PERMIAN TO THE TRIAS IN NOTIINGHAMSHIRE. 105

and younger than the St. Bees Sandstone. He also considers that
the Permian and the Trias are closely related ; but Goodchild went
farther, and united them into a New Red Sandstone System.

(7) Manchester District.

The Permian rocks near Manchester are known chiefly through
the researches of Binney (1841 & 1846). The following is his

classification.’ In descending order there are :—
Thickness in feet.
1. Strata of red and variegated marls, containing thin layers
of limestone and gypsum, and beds of sandstone; they
contain fossil mollusea of the genera Schizodus, Bake-

vellia, Pleurophorus, Turbo, Rissoa, ete.......... ...1eceeeee about 300
%. Conglomeratic browmsamQstONe .........0.<-vectecses-casoee about 50
3. Soft red or variegated sandstone (Collyhurst) ........... ... about 500
4. Conglomeratic sandstone (Astley), with pebbles of white

quartz and shingle with impressions of coal plants...... about 60

The fossils occur only in the red or variegated marls and their
numerous limestone-intercalations. They comprise 21 species in
all, which, H. B. Geinitz (1890, pp. 539 e¢ seqq.) says, establish the
Upper Zechstein age of the variegated marls.

Binney * was unable to point out a line of division between the
Permian and the Trias, and Geinitz says :—

‘In all cases where the variegated clays of the Upper Dyas or Upper
Permian, and those of the Lower Trias or Upper New Red Sandstones
are found in juxtaposition and actual contact, they appear, by the con-
formability of their stratification, to be intimately linked together.....
Where, again, the upper limestone appears more independent and of the
character of a pure marine formation, there is much less temptation to
refer the variegated clays or red clay shales at the basis of the variegated
sandstone to the Dyas.’ (Trans. Manch. Geol. Soc. vol. iv, 1864, p. 1383.)

In the discussion on the paper, Binney stated that the Permian
and the Trias (near Manchester) apparently passed into one another,
and were inclined at the same angles. They could only be distin-
guished by the fossils in the lower beds.

Ill. Patzonrotoegy or THE Upper MaGnestAN LIMESTONE.

The Bunter formation may be described as unfossiliferous in
England. A few imperfect plants have been recorded, as, for
example, those found by Mr. R. D. Vernon® at Colwick, Nottingham,
in the uppermost layers of the Pebble Beds; but these are of no value
for chronological purposes. In the absence of determinable fossils,
it is clearly impossible to say what animals and plants were in
existence during the period of the English Bunter; and it is unsafe
to assume that, if fossils should ever be found in these rocks, they
will prove to belong to a different period from those known to occur
in the Upper Magnesian Limestone of the English Permian.

* In Geinitz, 1890, p. 538.

* In Geinitz, 1864, p. 145.
° GW. Lamplugh & others, 1908, p. 42.

106 MR. R. L. SHERLOCK ON THE RELATIONSHIP OF THE [ Feb. 191 t,

The stratigraphical evidence already adduced points to the Upper
Magnesian Limestone being contemporaneous with part of the
Bunter. It will be useful now to give some account of the
paleontology of the Upper Magnesian Limestone.

The most important work on British Permian Paleontology is
King’s ‘ Monograph of the Permian Fossils of England’ (1860),
which gives a complete account of all that was known of the
subject at the date of publication, and is still a standard work.
J. W. Kirkby (1861) described the fauna of the South Yorkshire
Permian, and gave a list of the species known at that time from the
Upper and Lower Limestones; and a few additional species are
mentioned in the Survey Memoirs. A full list of the species in

the Lancashire Permian is given by Geinitz,! with an addition by
Mr. Roeder.”

find that the

Combining the lists from these (apparently the only) sources, we

comprise :—
PLANTS,

ALGA.

Spongillopsis dyadica Geinitz.
Chondrus (¢) binneyt King.

ConiFERz.
Voltzia liebeana Geinitz.

PALM&.
Guilielmites permianus Geinitz.

ANIMALIA.

Ruizopopa.
Dentalina permiana Jones.
Dentalina kingit Jones.
Dentalina (?).
Textularia triticum Jones.
Textularia cunetformis Jones.

Speoncia.
Tragos binneyt King.

‘VERMES.
Spirorbis permianus King.
Vermilia obscura King.
Serpula (?) pusilla Geinitz.
Filograna permiana King.

LAMELLIBRANCiIIATA.
Avicula (Monotis) kazanensis de
Vern.
Avicula (Monotis) garforthensis
King.*

fauna and flora of the Upper Magnesian Limestone

LAMELLIBRANCUHIATA (cont.).
Mytilus septifer King.
Mytilus squamosus J. de C. Sow.
Myalina hausmanni Goldf.
Bakevellia antiqua Minster.*
Leda vinti King.
Leda speluncaria Geinitz.
Pleurophorus costatus Brown.
Schizodus schlotheimi Geinitz.
Schizodus rotundatus Brown.
Schizodus truncatus King.
Schizodus obscurus (J. Sow.).
(2) Edmondia elongata Howse.
Cleidophorus pallasi (de Vern.).

ScariHopoDa.
Dentalium speyert Geinitz.

PoLYPLACOPHORA.
Chiton (2).

GASTROPODA.

Turbo helicinus Schlotheim.
Turbo mancuniensis Brown.
Turbo permianus King.
Rissoa obtusa Brown.
Rissoa leight Brown.
Rissoa gibsont Brown.
Natica minina Brown.

PISCES.
Gyropristis obliquus Agassiz.*
Paleoniscus longissimus Agassiz.*
Pal@oniscus catopterus Agassiz.*

The species marked with an asterisk * are described by King

1 Hf, B. Geinitz, 1890, pp. 551-52.

2 ©, Roeder, 1892, p. 118.

Vol.67.] | PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 107

as ‘ probably ’ belonging to the highest Permian deposits. In the
foregoing list the genera have been arranged in classes, according
to the classification adopted by Zittel in his ‘Grundztge der
Paliontologie’ (1903). )

Many of the generic and specific names have been altered by
later paleontologists; and the list given would be considerably
reduced, if it included only those forms which are generally
acknowledged to be distinct species. Thus Kirkby united all the
four forms of Schizodus into one species, Avinus obscurus Sow. :
which would now become Schizodus obscurus (Sow.), or Myophoria
obscura, if, with Prof. Steinmann (1907), we regard Schizodus as
inseparable from Myophoria. Similarly, Kirkby considered the
two species of Mytiius to be inseparabie from Myalina hausmannt
Goldf. King (with some hesitation) placed these forms in two
species of Mytilus, but Dr. Wheelton Hind (1897, p. 104) seems to
infer that they are really Myalina, and adds that

‘one is seemingly warranted in characterizing Myalina as a freshwater
genus.’

Zittel, in his ‘ Grundziige’ (1903), gives Silurian and Devonian as
the range of Myalina, and Trias to recent for Mytilus; while
Prof. Steinmann regards Myalina as part of the genus Geruillia.

Monotis is Triassic only, according to Zittel: Geinitz' made it
a subgenus of Avicula. Bakevellia was placed by him as a sub-
division of Gervilliz, but was accepted as a distinct genus by Zittel.
Prof. Steinmann does not mention the name at all, having apparently
included it under Gervillia.

Leda speluncaria Gein. is considered by King to be the same
as ZL. vintt King. The ? Edmondia elongata Howse, recorded at
Manchester by Geinitz, would appear to be wrongly named, since
the range of Hdmondia is given by Zittel as Carboniferous.

Cleidophorus is stated by Zittel to range from the Silurian to
the Devonian. The range in time of Dentalium is given by the
same authority as Silurian to recent.

Geinitz thought that Turbo mancunensis Brown was inciuded
in TY. helicinus Schl., and that Rissoa gibsonti Brown is probably
the same as R. leight Brown.

Of the sponge Z’ragos binneyi King, Dr. Hinde? says:

‘The type-specimen, now in the Museum of Queen’s College, Galway, shows

no traces of organic structures, and appears to me to be of inorganic origin.
It comes from Bradford, near Manchester.’

The Vermes are, of course, fossils of very indefinite characters.
Vermilia is not mentioned by Zittel, and appears to be referred
now to Serpula. Geinitz thought that Filograna might be a
pteropod: this name, also, seems to be no longer recognized.

The fish Gyropristis is not mentioned in Dr. A. 8. Woodward’s

©.

“Vertebrate Paleontology ’; but, in Woodward & Sherborn’s °

1H. B. Geinitz, 1890, p. 551. ? G. J. Hinde, pt. ii, 1888, p. 183.
3 A. S. Woodward & C. D. Sherborn, 1890, p. 91.

108 MR.R. L. SHERLOCK ON THE RELATIONSHIP OF THE [Feb. 1911,

‘Catalogue of British Fossil Vertebrata,’ it is described as a
? Permian ichthyodorulite from Belfast.

Alge are notoriously unsatisfactory as fossils, and it is not
surprising that both the generic names seem to have been dropped.
Voltzia is retained by Dr. Kidston’ as a Permian genus, and he
states that the specimens from Saxony in the British Museum
referred to V. liebeana Gein. appear to be the bracts of a Voltza
cone. There are probably no palms in the Permian; and Gurliel-
mites is a doubtful genus of Tertiary age (Schimper).”

Retaining the forms which are only ‘ probably ’ from the Upper
Limestone, but leaving out the bad and doubtful species, which are
useless for correlation purposes, the following are left :—

PLANTA.

ConiIrers.
Voltzia lieheana Geinitz.

ANIMALIA.
RHIZOPODA.

Dentalina permiana Jones.
Dentalina kingui Jones.
Textularia triticum Jones.
Textularia cuneiformis Jones.

VERMES.
Spirorbis permianus King.
Serpula () pusilla Geinitz.

LAMELLIBRANCHIATA.
Avicula (Monotis) kazanensis de
Vern.
Avicula (Monotis) garforthensis
King.

LAMELLIBRANCHIATA (cont.).
Myalina hausmanni Goldf.
Bakevellia antiqua Minster.
Leda vintt King.

Pleurophorus costatus Brown.
Schizodus obscurus (J. Sow.).

? Kdmondia elongata Howse.
Cleidophorus pallasi (de Vern.).

ScaPHopoDa.
Dentalium speyert Geinitz

GASTROPODA.
Turbo helicinus Schlotheim.
Turbo permianus King.
Rissoa gibsont Brown.
Natica minima Brown.

PISCEs.
Paleoniscus longissimus Agassiz.
Paie@oniscus catopterus Agassiz.

Considering the dates at which these fossils were named, it is
probable that, if they were examined by modern specialists, the
list would undergo considerable modifications.

If we consider now the affinities cf this fauna and flora, we find
that they are unquestionably Mesozoic.

The Rhizopoda and the Serpula belong to living genera, although
none of them are of any importance from the point of view of
affinities. Of the Lamellibranchs, Zittel states that Avicula and
Leda are still living; Plewrophorus ranged from the Devonian to
the Trias; Bakevellia is confined to the Permian, but the range of
the family to which it belongs (the Pernide) is said to be from
the Permian to the present time. Zittel does not recognize either
Edmondia or Cleidophorus as occurring in the Permian, hence
these forms probably are wrongly named generically, and in fact
the Hdmondia was queried by Geinitz. Schizodus occurs in the

1 R. Kidston, 1886, p. 17. 2 W. Ph. Schimper & A. Schenk, 1890, p. 372.

Vol. 67. | PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 109

Carboniferous (W. Hind, 1897) and Permian, but is Permian
only according to Zittel; and the genus is barely separable from
Myophoria, which is so typical of the Trias (see Steinmann,
Waagen,’ and Wohrmann ’).

From what has been said above, it is evident that the genus of
Myalina hausmanni is quite uncertain, and its affinities are there-
fore also uncertain. However, a species occurs in the Middle
Bunter °® of Germany, which is so like WV. hausmanna that for a long
time it was mistaken for it.

The scaphopod Dentaliwm is a persistent type, which still exists.

Turning to the Gastropoda, we find that the genus of the Natica
is doubtful; but, if the determination be correct, all the gastropoda
recorded belong to genera which are still living.

The genus Palwoniscus is usually regarded as an important link
with the Paleozoic, but the genus is exclusively Permian (A. 8.
Woodward, 1898, p. 86).

The plant Voltzia is typical of the Bunter, and is unknown in
the Carboniferous. .

Many of the fossils in the list are of restricted range, as, for
example, the Rhizopoda, which are recorded only from Dyer’s Quarry
(Durham). The two species, Myalina hausmannit and NSchizodus
obscurus, are by much the commonest fossils, and in South York-
shire and Nottinghamshire the only fossils that are found. Their
‘wide distribution enables us to correlate the Upper Magnesian Lime-
stone of England with the upper part of the German Zechstein,
although it is to be remembered that both species occur also in the
Lower Magnesian Limestone.

The southernmost occurrence of the Zechstein in Germany is
near Heidelberg; but in the Bavarian Palatinate, on the other
side of the Rhine, there occurs a dolomitic bank, in red chalky
beds and clayey sandstones, which were regarded as Bunter, until
Myalina hausmanni and Schizodus obscurus were found in them.
Here we have proof of a Bunter facies of the Upper Magnesian Lime-
stone, such as is claimed to occur at Nottingham.

Mention has already been made of the presence of a shell closely
resembling M. hausmanni (Aucella of Geinitz) in the Bunter.
This occurs in the sandstone, north of Salza, north-west of Langen-
bogen (Ebert, loc. cit.). The fossil is of common occurrence, and is
accompanied by Gervillia murchisont, the characteristic fossil of
the Middle Bunter.

It seems, then, that the paleontological evidence is
not opposed to the idea that the Upper Magnesian
Limestone of England is contemporaneous with part
of the Bunter.

1 W. Waagen, 1881, p. 241.
2 §. von Wobhrmann, 1894, p. 2.
3 Th. Ebert, 1889, p. 241.

110 = MR. R. L. SHERLOCK ON THE RELATIONSHIP OF THE [Feb. 1911,

LV. Conciusions.

In considering the relation of the Permian and the Trias in the
North of England, the nature of the junction of the Permian Middle
Marl with the Bunter in South Nottinghamshire is of fundamental
importance. Ina previous section stratigraphical evidence has been
adduced to prove that the junction is a strictly conformable one;
that the Permian Marl merges imperceptibly into the Bunter above;
and that, consequently, we must assume that the deposition of the
Bunter commenced immediately after the Permian Middle Marl had
been laid down. The evidence relied on is:

(1) An apparent perfect upward passage from the Marl to the Bunter,

visible in the Great Central Railway-cutting between Annesley and
Kirkby ;

(2) A similar section in the Great Northern Railway near Kimberley ;

(3) The fact that these cuttings are 6 miles apart shows that the
apparent conformity extends over at least this distance, and is very
probably, therefore, a real conformity ;

(4) Other sections in brickpits, etc. showing similar relations, at intervals
between Nottingham and Mansfield.

To these arguments more general ones may be added.

The thickness of the Middle Marl in South Nottinghamshire is
from 10 to 20 feet, so that if there was an unconformity between
it and the Bunter amounting to 1° only, the Marl would be entirely
overlapped in a distance of 300 yards (taking the thickness at a
maximum). It has, however, been followed continuously from
Nottingham to Mansfield (a distance of 12 miles), and in the whole
of that distance its apparent thickness varies by only a few feet.
Outlying spurs of high ground also enable us to trace it across the
strike, as from Watnali Chaworth to Bulwell (a distance of 3
miles}, or from Skegby to Mansfield (a distance of 2 miles); and
here again the outcrop does not show any signs of being overlapped.
These facts can only be accounted for by a perfect conformity of
the Permian Marl with the Bunter.

The folding map (PI. V) shows that the Bunter and the Permian
have an identical strike; whereas the Bunter and the Keuper,
between which there is evidence of a slight unconformity, have
slightly different strikes.

Some possible objections have already been dealt with. The
absence of the Permian Marl at Mansfield, for about a milein a
north and south direction, has been shown to occur in conjunction
with curious local characters in the limestone below; and a theory
which explains both of these phenomena has been suggested, namely :
that limestone and marl are replaced at this point by the bar of a
Permian river, and that the Marl is really represented by sandrock
which has been mistaken for Bunter. At Warsop, where the Marl
again does not appear, the ground is overlain with alluvial deposits,
and this may prove to be the explanation of the apparent absence
of the Marl. On the other hand, the base of the Bunter is very
marly, and its lower portion may here represent the Marl.

An explanation of the successive disappearance of the Permian
subdivisions from north to south, alternative to that of uncon-
formable overlap by the Bunter, is that each member of the

Vol. 67.] PERMIAN 10 THE TRIAS IN NOTTINGHAMSHIRE. TTI

Permian is thinning southwards: the upper member disappearing
first and the lowest last. here is no doubt that the Permian
deposits do thin southwards, and also (as is shown by borings)
westwards, as does the Trias above. The explanation is, however,
insufficient to account for the facts. While the Trias as a whole thins
southwards, its lower members thin northwards: it is suggestive,
at the least, that as the Permian Marl and Upper Magnesian
Limestone develop northwards, so does the Lower Mottled Sand-
stone diminish, and, after this has entirely disappeared, the Pebble
Beds above lose in importance and finally disappear also, leaving
the Keuper resting directly upon the fully developed ‘ Permian.’

The conditions of deposition of the Permian and Triassic rocks is.
still largely a mystery. It is, however, clear that the magnesian
limestones and the Keuper were formed in a Caspian Sea, and that.
the Bunter is probably non-marine.*

The thin Permian of Nottingham, which is distinctly a littoral
formation, can scarcely be the time-equivalent of the thick deposits
of Durham, which consist of 800 feet of limestone. But the Marl
Slate with its fossils occurs at the base of the series in both places,
and therefore the upper part of the Durham Limestone is newer than
any part of the Nottingham Permian, a fact corroborated by such fossil
evidence as exists. Now, the Nottingham Permian was immediately
followed by Bunter, so that the upper part of the Durham Mag-
nesian Limestone is the chronological equivalent of some part of the
Nottingham Bunter: that is, both are Permian or both are Trias.

We know that the early Zechstein sea had its southern limit
at Nottingham, and-its western limit not far to the west of the
present outcrop: hence the assumption of a gentle uplift acting
during Zechstein times, and causing the coast-line to migrate in a
north-easterly direction, would account for Bunter being formed
towards the south, perhaps by torrential floods on the flat coast-
lands, contemporaneously with the continued formation of limestone
off the coast. Meantime the sea-hottom was slowly subsiding in
the Durham area, allowing of the formation of a thick mass of
shallow-water limestone. There would, therefore, be a slowly
rising area in the south and a slowly sinking area in the north ;
while the line about which the movement turned migrated in a
north-easterly direction. It appears that, at the end of the period,
the sea, always of a Caspian character, became increasingly salty.
This is indicated by the poverty of the fauna and dwarfed nature of
the fossils in the Upper Limestone,” and by the occurrence of rock-
salt and gypsum in Durham, towards the end of the period. The
Keuper, which followed, indicates a slight inroad of the sea, which
was still, however, very salt, for dolomite, gypsum, and rock-salt.
occur in this series also.

It is probable that, in at least the southern half of the district, -
there occurred a slight check to the slow steady rise of the area,
during Permian times. Thisis indicated by the slight unconformity
between the Lower Limestone and the Middle Marl, which has

1 T. G. Bonney, 1908, p. 337; and J. Lomas, 1907, p. 511.
2 J. W. Kirkby, 1861, p. 316.

112 MR. R.L. SHERLOCK ON THE RELATIONSHIP OF THE [Feb. 1911,

been seen at intervals between Nottingham and Tadcaster. The
Marl indicates somewhat deeper water than the limestone (which
at Mansfield shows reptilian footprints and ripple-marks), and the
passage-bed above it is very lke the Keuper Waterstones in
appearance, and therefore probably had a similar origin. Now, the
Waterstones seem to indicate shallower water than the Keuper
Marl above: for they are composed of coarser sediment, and the beds
are not only ripple-marked but even sun-cracked in places; and
the Permian Mar] is lithologically very like the Keuper Marl. It
appears, therefore, that, after the slight depression which ended the
formation of the Lower Limestone and caused the Marl to be
deposited, the steady rise set in again immediately.

The close of the Permo-Bunter period was brought about by a
change in these movements. In the south, the Bunter was covered
by the sea, for the Keuper Waterstones were deposited in water ;
and there appears to be a slight unconformity between them and
the Bunter. In the north, there may or may not have been a
change of movement, since both Waterstones and Magnesian
Limestone are shallow-water deposits. The difference between
them may be merely a question of the supply of sediment, for, as
was remarked above, the Waterstones contain much dolomite.
All that seems necessary, therefore, to bring about the change from
Permo-Bunter to Keuper conditions was the sinking of the southern
area below a very shallow sea, with the consequent alteration of
currents in the north. The Waterstones extend over the whole
of the north-eastern basin; and slow subsidence, causing slight
deepening of the water, would bring about ‘the gradual change
which caused Keuper Marl to follow the Waterstones imperceptibly.
All this time, however, the sea remained of Caspian character,
until, at last, the open sea found an entrance and the Rheetic beds

were formed.
These considerations lead to the following correlation-table :—

South NorrinGHAMSHIRE. SouTH YORKSHIRE. DuRHAM.
Keuper Marl. Keuper Marl. Salt "
} Keuper.
Keuper Waterstones. Keuper Waterstones. Measures.
Probable slight unconformity.
Pebble Beds. i ( Pebble Beds. 7 eat
Lower Mottled Sandstone | __} Upper Marl (local). Wnper Mae Lime-
( and Passage Beds.) | ieee enosian Lime- iat) Mid dleMagnesian ne
Middle Marl. Middle Marl. pet:
Lower Magnesian Lime-
Lower Magnesian Lime- Lower Magnesian Lime- stone.
stone. stone. J
Basement Beds (local). Basement Beds (local). Basement Beds (local).

It is to be noted that the Basement Beds are local and may not be strictly
contemporaneous everywhere. Kirkby (1861, p. 317), in fact, regarded the
Marl-Slate of Durham as contemporaneous with part of the Lower Magnesian
Limestone of South Yorkshire.

Vol.67.] PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 113

A small unconformity, between the Magnesian Limestone and
the Marl above it, is recorded by Goodchild as occurring at St. Bees
Head. The succession there is so similar to that of South
Nottinghamshire (showing in both alike the order :—limestone ;
small uncontormity ; followed by Marl passing upwards through
beds resembling Waterstones into Bunter) that one is tempted to
correlate the two, although they were formed in distinct basins.

In the Manchester district the Upper Magnesian Limestone is
shown, by the fossils,’ to be represented by red clays with only
subordinate bands of limestone, and here also there is not known
to be any break between these beds and the Trias above, which is
said to be of Bunter type.”

Dr. H. T. Brown has described * an unconformable junction of the
Trias and Permian at Swadlincote (Leicestershire), where there is
© to 8 feet of Bunter conglomerate and sandstone resting uncon-
formably upon 27 feet of Permian sandstone, clay, and breccia, and
covered by Lower Keuper. It is evident that these thin beds
cannot represent, chronologically, much of the thick Bunter and
Permiar deposits of other districts. The unconformity observed
~at Swadlincote may, therefore, be supposed to represent some part
of the strata seen in the Nottingham area: if, indeed, the *‘ Bunter’
is not really the basement- bed of the Keuper, such as may be seen
at Nottingham.

Correlations of beds in distinct areas are, however, not very
certain, as was pointed out by Green.* He remarked that
deposits such as those of the Permian, formed in so many distinct
basins and under changing conditions, must necessarily be totally
different in different areas. He objected to the habit of desig-
nating subdivisions of the English New Red by German names,
For example, there was no proof that the New Red Sandstone was
the time-equivalent of the Bunter.

The question of the independence of the Permian and Triassic
Systems is a wide one, and can only be settled by a consideration
of the strata in other regions of the earth, as well as in Britain.
The evidence from Nottinghamshire, however, is of importance,
because the Nottingham district has been relied on for proof of a
break between Permian and Trias, which, elsewhere in this country,
has failed to bear investigation. Thus Mr. H. B. Woodward,
while supporting the indivisible character of the Permo-Trias,
points to Nottinghamshire as a difficulty, and writes :—

‘Near Nottingham there is evidence of the overlap of Permian rocks by the
Trias, which crosses some of its upper divisions, and finally rests on the Coal-
Measures. Even here there is no positive evidence of denudation between the
Permian and Bunter formations, inasmuch as the overlap by the Bunter Sand-
stone may have coincided with a depression of the area that took place after
the Upper Permian Beds were deposited.’ (1887, p. 209.)

1 H. B. Geinitz, 1890, p. 539. 2 See J. W. Gray & P. F. Kendall, 1894,
3 ‘The Permian Rocks of the Leicestershire Coal-Field’ Q. J. G. 8S. vol. xlv
(1889) pp. 1-40. * A. H. Green, 1887, p. 290.

@..5..G. Se No: 265. I

114 MR. RL. SHERLOCK ON THE RELATIONSHIP OF THE | Feb. 1911,

_ The conformability of Permian and Bunter in this district removes,

therefore, the only exception to the rule, and tends to prove that
in England there is a New Red Sandstone System comprising all
the strata between the Carboniferous and the Jurassic Systems.

V. SumMARY.

1. In Nottinghamshire the Permian and the Bunter are shown
to be conformable.

2. Part of the ‘ Bunter’ of South Nottinghamshire is contempo-
raneous with the Upper Magnesian Limestone of North
Nottinghamshire ; and the ‘ Bunter’ of South Notting-
hamshire, as a whole, is contemporaneous with the upper
part of the Magnesian Limestone Series of Durham.

3. An explanation of the mode of origin of the White and Red
Sandstones of Mansfield is given.

4, The paleontology of the Upper Magnesian Limestone is
discussed, and the evidence derivable from the fossils is shown
to be not unfavourable to the view stated in 2.

VI. BrsiioGRAPHy.

AVELINE, W. T.—‘ The Magnesian Limestone & New Red Sandstone in the
Neighbourhood of Nottingham’ Geol. Mag. dec. 2, vol. iv (1877) pp. 155-56.

AvetineE, W. 'I’.—‘ The Relation of the Permian to the Trias’ Ibid. p. 380.

AVELINE, W. T.—‘ The Geology of Parts of Nottinghamshire & Derbyshire’ Mem.
Geol. Surv. 2nd edit. 1879.

AveEtinge, W. T.—‘ The Geology of the County around Nottingham’ Mem. Geol.
Surv. 2nd ed. 1880.

Avettne, W. T.—‘ The Geology of Parts of Nottinghamshire, Yorkshire, & Derby-
shire’ Mem. Geol. Surv. 2nd edit. 1880 (No. 2).

Aveuine, W. T., A. H. Green, J. R. Daxyns, J. C. Warp, & R. Russeryt.—
‘The Geology of the Carboniferous Rocks North & East of Leeds, and the
Permian & Triassic Rocks about Tadcaster’ Mem. Geol. Surv. 1870.

Binney, E. W.—‘Sketch of the Geology of Manchester & its Vicinity’ Trans.
Manch. Geol. Soc. vol. i (1841) pp. 35-66.

Binney, E. W.—‘ On the Relation of the New Red Sandstone to the Carboniferous
Strata in Lancashire & Cheshire’ Q.J.G.S. vol. 11 (1846) pp. 12-26.

Bonney, T. G.— On the Evidence for Desert Conditions in the British Trias’ Geol.
Mag. dec. 5, vol. v (1908) pp. 337-41.

CantTrity, T. C.—‘ On the Occurrence of Spirorbis-Limestone & Thin Coals in
the so-called ‘‘Permian~% Rocks of Wyre Forest; with Considerations as to the
Systematic Position of the “ Permians” of Salopian Type’ Q. J. G. S. vol. li
(1895) pp. 528-548.

CHAMBERLIN, I’. C., & R. D. SarissuRy.—‘ Geology’ vol. 11 (New York & London,
1906).

DE eee E.— ‘11th Report of the British Association Committee on Under-
ground Waters’ Rep. Brit. Assoc. (Aberdeen) 1885, pp. 380-95.

Dunston, G.—‘ The Eastern Extension of the Midland Coalfield, & the Explor-
ation at Southcar’ Trans. Inst. Min. Eng. vol. xii (1896-97) pp. 515-24.

Durnrorp, H. St. J.—‘ Deep Boring at Barlow, near Selby’ Lbid. vol. xxxiv
(1907-1908) pp. 426-48.

Exsert, Tu.—‘ Ueber die Art des Vorkommens & die Verbreitung von Gervillia
murchisoni Geinitz im Mittleren Buntsandstein’ Jahrb. K. Preuss. Geol.
Landesanst. 1888 (1889) pp. 237-42.

Fox-Straneways, C.—‘ Sections along the Lancashire, Derbyshire, & East Coast
Railway between Lincoln & Chesterfield’ Q. J.G.S. vol. liv (1898) pp. 157-
68 & pl. x.

Vol. 67.] PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 115

Fox-Srraneways, C.—* The Geology of the Country North & East of Harrogate’
2nd ed. Mem. Geol. Surv. 1908.

Garwoop, E. J.—‘ On the Origin & Mode of Formation of the Concretions in the
Macnesian Limestones of Durham’ Geol. Mag. 1891, pp. 433-40 & pls. xii-
xiil.

Gernitz, H. B.—‘ The Dyas or Permian Formation in England’ [Transl. by
E. W. Binney] Trans. Manch. Geol. Soc. vol. iv (1864) pp. 121-46.

Geinitz, H. B—On the Red & Variegated Marls of the Upper Dyas, near
Manchester ’ [Transl. by Mark Stirrup] Ibid. vol. xx (1890) pp. 537-54.
Gipson, W.— On the Character of the Upper Coal-Measures of North Staffordshire,
Denbighshire, South Staffordshire, & Nottinghamshire ; & their Relation

to the Productive Series’ Q. J. G. S. vol. lvii (1901) pp. 251-66.

Grgson, W., T. I. Pocock, C. B. Wepp, & R. L. SHERLocK.—‘ The Geology of
the Southern Part of the Derbyshire & Nottinghamshire Coalfield’ Mem.
Geol. Surv. 1908.

GoopcHILp, J. G.—‘ Observations on the New Red Series of Cumberland &
Westmorland, with Especial Reference to Classification’? Trans. Cumberland
& Westmorland Assoc. for the Advancement of Lit. & Sc. No. xvii (1891-92)
pp. 1-24 & 2 pls. (reprint).

Gray, J. W., & P. F. Kenpatt.—‘ On the Junction of Permian & Triassic Rocks
at Stockport ’ Rep. Brit. Assoc. (Nottingham) 1893, pp. 769-70.

Green, A. H.— The Geology of Northumberland & Durham’ (Review of ‘ Out-
lines of the Geology of Northumberland & Durham’ by G. A. Lebour)
Nature, vol. xxxvi (1887) pp. 289-90.

GREEN, A. H., & R. Russert. The Geology of the Neighbourhood of Wakefield
& Pontefract ? Mem. Geol. Surv. 1879.

HicKxiine, G.—‘ On Footprints from the Permian of Mansfield (Nottinghamshire) ’
Q. J. G. S. vol. lxii (1906) pp. 125-31.

Hinp, WHEELTON.— Monograph of the British Carboniferous Lamellibranchiata ’
pt. 11, Paleont. Soc. 1897.

Hinpr, G. J.— A Monograph of the British Fossil Sponges’ Palzont. Soc.

Houmes, T. V—‘ The Permian, Triassic, & Liassic Rocks of the Carlisle Basin’
Q. J. G. S. vol. xxxvii (1881) pp. 286-98 & pl. xi.

Howe.tt, H. H.— Note on the Classification of the Red Rocks in South-East
Durham ; and on a Possible Unconformity between the Trias & the Permian
Limestone in the same District’ Geol. Mag. dec. 3, vol. vii (1890) pp. 8-13.

Hout, E.—‘ The Geology of the Country around Oldham’ Mem. Geol. Surv. 1864.

Hutt, E.—‘The Triassic & Permian Rocks of the Midland Counties of England ’
Mem. Geol. Surv. 1869.

Huu, E.—In ‘ On the Manufacture of Salt near Middlesbrough’ by Sir Lowthian
Bell, Proc. Inst. C. E. vol. xc (1887) pp. 131-45, &c.

Hott, E., & A. H. Green. The Geology of the Country round Stockport,
Macclesfield, Congleton, & Leek’ Mem. Geol. Surv. 1866.

Irvine, Rev. A—‘ On the so-called “ Permian” & the New Red Sandstone
Formations’ Geol. Mag. dec. 2, vol. iv (1877) pp. 309-12.

Irvine, Rev. A.—‘ On the Classification of the European Rocks known as Permian
& Trias’ Geol. Mag. dec. 2, vol. ix (1882) pp. 158-64, 219-23, 272-78,
316-22.

Kenpatt, P. F.—‘ On the Brockrams of the Vale of Eden, & the Evidence they
afford of an Inter-Permian Movement of the Pennine Faults’ Geol. Mag.
dec. 4, vol. ix (1902) pp. 510-13.

Krpston, R.— Catalogue of the Paleozoic Plants in the Department of Geology &
Paleontology, British Museum (Natural History) ’ London, 1886.

Kine, W—A Monogr aph of the Permian Fossils of England’ Palzont. Soc. 1850.

Kirxsy, J. W.—‘ On the Permian Rocks of South Yorkshire; & on their
Palzontological Relations’ Q. J. G. S. vol. xvii (1861) pp. 287-325 & pl. vii.

LAMPLUGH, G. W., W. Grsson, R. L. SHertocx, & W. B. Wricut.— The
Geology of the Country between Newark & N ottingham > Mem. Geol. Surv.
1908.

Lomas, J.— Desert Conditions & the Origin of the British Trias’ Geol. Mag.
dec. 5, vol. iv (1907) pp. 511-14, 554-63.

Movrcuison, Sir Ropericx, & R. Harkness.—‘ On the Permian Rocks of the
North-West of England, & their Extension into Scotland’ Q.J.G.S. vol. xx
(1864) pp. 144-65.

Ramsay, Sir ANDREw.—‘ On the Recurrence of Certain Phenomena in Geological
Time’ Rep. Brit. Assoc. (Swansea) 1880, pp. 1-22.

1Z

116 MR. R. L. SHERLOCK ON THE RELATIONSHIP OF THE [| Feb. 1gII,

RoEpDER, C.—‘ Notes on the Permians & Superficial Beds at Fallowfield’ pt. ii,
Trans. Manch. Geol. Soe. vol. xxi (1892) pp. 104-18.

ScuimPer, W. Pu., & A. ScHenx.—In K. A. Zittel’s ‘ Handbuch der Palaeontologie”
II. Abtheil. Palaophytologie, Munich, 1890.

SrpewicxK, A.—‘ On the Geological Relations & Internal Structure of the Magnesian
Limestone, & the Lower Portions of the New Red Sandstone Series in their
Range through Nottinghamshire, Derbyshire, Yorkshire, & Durham, to the
Southern Extremity of Northumberland’ Trans. Geol. Soc. ser. 2, vol. ili,
pt. 1 (1829) pp. 37-124.

Srpewickx, A.—‘ On the New Red Sandstone Series in the Basin of the Eden, &
North-Western Coasts of Cumberland & Lancashire’ Ibid. vol. iv, pt. ii (1836)
pp. 383-407.

Sorpy, H. C.—Anniversary Address, Q. J. G.S. vol. xxxv (1879) Proc. pp. 56-95. '

Steinmann, G.—‘ Einfiihrung in die Palaontologie’ 2nd ed. Leipzig, 1907.

‘Summary of Progress for 1903’ Mem. Geol. Surv. 1904.

‘Summary of Progress for 1908’ Mem. Geol. Surv. 1909.

Tate, T.—‘ Notes on Recent Borings for Salt & Coal in the Tees District’ Q.J.G.S.
vol. xlviii (1892) pp. 488-95.

TEatt, J. J. H—‘ The Pennine Chain’ Geol. Mag. dec. 2, vol. vii (1880) pp. 92-93.

Waacen, W.—‘ Palzontologia Indica, ser. xiii, Salt Range Fossils, vol. i: Productus
Limestone Fossils, 111. Pelecypoda’ Mem. Geol. Surv. India, 1881.

Warp, J. C.—‘ On Beds of supposed Rothliegende Age, near Knaresborough, &c.”
Q. J. G.S. vol. xxv (1869) pp. 291-97.

Wits, L. J:—‘ On the Fossiliferous Lower Keuper Rocks of Worcestershire, with
Descriptions of some of the Plants & Animals discovered therein’ Proc. Geol.
Assoc. vol. xxi (1910) pp. 249-331 & pls. x—xxvi.

Witson, E.—‘ On the Permians of the North-East of England (at their Southern
Margin), & their Relations to the Under- & Overlying Formations’ Q.J.G.S.
vol. xxxil (1876) pp. 533-37.

Witson, E.—‘ The Magnesian Limestone & New Red Sandstone in the Neighbour-
hood of Nottingham’ Geol. Mag. dec. 2, vol. iv (1877) pp. 238-240.

Witson, E.—‘ On the South-Scarle Section’ Q. J. G.S. vol. xxxv (1879) pp. 812-13.

Witson, E.—‘ The Age of the Pennine Chain’ Geol. Mag. dec. 2, vol. vii (1880)
pp. 93-95.

Witson, E.—‘ The Permian Formation in the North-East of England, with Special
Reference to the Physical Conditions under which these Rocks were Formed”
Midland Naturalist, vol. iv (1881) pp. 97-101, 121-24, 187-91, 201-208.

Witson, E.—‘ On the Durham Salt-District’ Q. J. G. S. vol. xliv (1888) pp. 761-
782.

WouRmMann, Baron S. von.—‘ Ueber die systematische Stellung der Trigoniden &
die Abstammung der Nayaden’ Jahrb. K.-k. Geol. Reichsanst. vol. xlin
(1893-94) pp. 1-28.

Woopwarp, A. S.— Outlines of Vertebrate Paleontology ’ London, 1898.

Woopwapp, A.S.,& C. D. SHERBORN.—‘ A Catalogue of British Fossil Vertebrata”
London, 1890.

Woopwarp, H. B.—‘ Remarks upon the Relations & Grouping of the Permian &
Triassic Rocks’ Geol. Mag. dec. 2, vol. 1 (1874) pp. 385-90.

Woopwarp, H. B.— The Geology of England & Wales’ 2nd ed. London, 1887.

Wootacott, D.—‘ Preliminary Note on the Classification of the Permian of the
North-East of England’ Rep. Brit. Assoc. (Winnipeg) 1909, pp. 476-77.

ZittEL, K. A. von.—‘ Grundziige der Palaontologie ’ Munich, 1903.

Maps.
Geological Survey Maps. Old Series.

Sheet 71. N.W., Belper; 71. N.E., Nottingham ; 82. S.W., Chesterfield; 82.S.E.,
Mansfield; 82. N.W., Sheffield; 82. N.E., Tickhill; 87. S.W., Barnsley; 87. S.E.,
Doncaster ; 87. N.W., Wakefield ; 87. N.E., Snaith.

New Series.

Sheet 125. Derby; 126. Nottingham; 70. Leeds; 62. Harrogate; 61. Pateley
Bridge; 52. Ripon; 51. Bedale Masham; 42. Northallerton; 41. Richmond; 33.
Stockton; 32. Staindrop; 27. Durham; 26. Bishop Auckland; 21. Sunderland ;
15. Tynemouth.

Quart. Journ. Geol. Soc. Vol. LX VII, Pl. V.

MAP OF THE:

PERMIAN AND TRIAS
OF THE

NORTH-EAST OF ENGLAND.

Scale:10 Miles to an Inch.
EXPLANATION.

AVOViIe 208

_Keuper Marl...

a

< {

as
Inner

ey

Limes HT

Hint

—

—

Quart, Journ. Geol. Soc. Vol. LXVII, Pl, V.

MAP OF THE
PERMIAN AND TRIAS
OF THE
NORTH-EAST oF ENGLAND.

Scale:10 Miles to an Inch.

4A EXPLANATION.
DURHAM, cee

Alluvium...

ea
Ferryhill __ SEES SSHARTLE-
2 ae ay ROOL

Keuper Marl............

Keuper Waterstones

Bunter Pebble Beds.
IDDLES-
BROUGH Lower Mottled

Sandstone .....

Upper Magnesian )

Limestone s
PermianMiddleMar! =
Lower Magnesian ft =

Limestone j

fe

; bid
i Shi
ee : ;

fe!
A

Vol. 67.] PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE, 117

EXPLANATION OF PLATE V.

Map of the Permian and Trias of the North-East of England,
on the scale of 10 miles to the inch.

Discussion.

Prof. Boyp Dawxtns said that he had studied the district chiefly
from the point of view of water-supply. He referred to a series
of borings which proved the singularly persistent eastward thickening
of the Permian marls. A revision of the geological survey had
been needed for many years, and he was glad that it was in such
competent hands as those of the Author.

The Avrnor, in reply, said that the information obtained from a
number of deep borings to the east of the Permian outcrop was
summarized in the paper. The sections showed a thickening of the
Permian rocks eastwards and the passage of the Lower Magnesian
Limestone into grey mudstones and shales, indicating deeper water
towards the east.

118 DR. W. F. HUME ON SECULAR OSCILLATION IN EG¥PT [Feb. 1911,

3. The Errects of Secutar Oscrntation im Eeyper during the
Cretaczous and Kocrens Prrtops... By Wirt1am Fraser Hume,
D.Se., Assoc.R.C.8., Assoc.R.S.M., F.G.S., Director of the
Geological Survey of Egypt. (Read November 23rd, 1910.)

[Pirate VI—Gxroxoercat Map. |

ConTEnTS.

Page
T, Introduction «........<:cag4g reer ree- 6 .h-> .scchdoehee a eee eee 118

II. Variations in the Fossiliferous Cretaceous Strata, and their
Relation to the Nubian Sandstone ...........5..:2..:«-.:seess eee 119
LTT, ‘Fhe Hammam, Types. casesterececises 7 lax .0e<2 «ie: quo 8e a eee ees 124
IV. The Danian Extension in Eastern Egypt: ...............ccs0cc0eseee 124
V. The Southern Cretaceous Type ........0.--.0.cccseeseeeeres 7: eames 129
VI. Summary of Cretaceous History in Egypt..................04 ame sie pe
VII. Transition from the Cretaceous to the Eocene Period ......... .. 131
VIII. The Faunal History of Egypt during Eocene Times ............ 133
TX, General Summary, 2.73 eee ees. cae .-s:. sneer 143

I. IntrRopvcrttion,

In the year 1878 Prof. Zittel? laid the foundations of modern
Egyptian sedimentary geology on a broad basis, since which period
the Cretaceous and Kocene strata of that country have aroused
much interest. The problems which have especially appealed to
investigators are :—

(1) The age of the Nubian Sandstone.

(2) The changes of the fossiliferous Cretaceous strata when traced from
north to south.

(3) The nature of the junction between the Eocene and the Cretaceous.
(4) The distribution and variation in the Eocene beds.

(5) The nature of the changes which have marked the passage from the
Eocene to the Oligocene Period.

The work carried out by the Egyptian Geological Survey has,
since 1896, widened our knowledge of the facts on which the
broader theoretical conclusions will have to be based ; and, in the
present contribution, I shall endeavour to set forth the new data
which have been obtained by me in connexion with each of
these questions, only referring to the results of other investigators

1 In view of the new facts obtained during the expedition of 1910, the
author was permitted to rewrite his paper on ‘The Cretaceous & Eocene
Strata of Egypt,’ presented to the Geological Society in 1909, so as to include
these results.

2K. A. von Zittel, ‘Ueber den geologischen Bau der Libyschen Wiiste’”
(Festrede) K. Bayerisch. Akad. Wissensch. 1880, and ‘ Beitrige zur Geologie
& Palaoutologie der Libyschen Wiiste, &c.’ Paleontographica, vol. xxx, 1883.

Vol. 67.] DURING THE CRETACEOUS AND EOCENE PERIODS. 119

where these are necessary to complete the consideration of areas
which have not been personally investigated. The portions of
Egypt which have thus come under personal study are :—

(1) Eastern Sinai.
(2) A longitudinal region bordering Wadi Qena.

(3) The area between latitudes 25° N. and 28° N. covered by the Eastern
Desert Survey Memoirs of 1903 and 1906.

(4) The districts bordering the Nile between Esna and Aswan.

(5) A series of traverses across the Western Desert between the Oases of
Dungul, Kurkur, Kharga, and the city of Edfu, with a brief study of
the Arbain road south of Kharga.

(6) Traverses from the Nile to Baharia, embracing visits to the Moela
Oasis and the Fayum.

(7) Studies in the neighbourhood of Cairo (Moqattam Hills, Abu Roash,
Helwan, etc.).

Owing to results obtained during 1910, it is no longer possible,
in my opinion, to treat the Nubian Sandstone and the fossiliferous
Cretaceous strata as separate entities, but they should now be con-
sidered as parts of a single series. From this remark the Carbo-
niferous sandstone and limestone present in Wadi Araba and
Western Sinai must be excluded, as these contain Carboniferous
fossils. As no fossils of this age have at present been noted else-
where in Egypt, it is Baobable that these strata have only a limited
development.

Il. VARIATIONS IN THE FossILIFEROUS CRETACEOUS STRATA, AND
THEIR RELATION To THE NUBIAN SANDSTONE.

The gradual advance of the sea over many continental lands
during the Upper Cretaceous Period is one of the best established
of geological hypotheses, and Egypt contributes a striking illus-
tration of this general tendency. The predominance of deep-water
conditions in she north is witnessed by the deposition of limestones
throughout the whole of Upper Cretaceous times; only farther south
is the presence of continental areas indicated by the occurrence
of the well-known Nubian Sandstone, which, of relatively minor
importance in Northern Egypt, in the south is the dominant
member of the Cretaceous System. Several phases may be
recognized, in which the organic and detrital deposits differ con-
spicuously as regards their distribution in time and space, marking
successive stages in the gain of sea over land. . The Cretaceous
strata here considered consist of (1) the Danian, (2) the Campanian
and Santonian divisions of the Senonian or Upper Chalk, (3) the
Turonian or Middle Chalk, and (4) the Cenomanian or Lower Chalk.
The French terms will be used throughout this paper.

120 DR. W. F. HUME ON SECULAR OSCILLATION IN EeyPr [Feb. rg11,

(A) The Cretaceous Strata of Northern Egypt.

In Egypt the northernmost Cretaceous belt, extending from
Southern Sinai through the Gebel Atagqa and Galala Hills to Abu
Roash, with a western extension in the Baharia Oasis, is charac-
terized by a great development of limestones during Danian,
Senonian, and Turonian times.

The Cenomanian beds are also highly fossiliferous, but the strata
are marls in Sinai and of a more sandy nature in the Baharia Oasis.
The unfossiliferous Nubian Sandstone immediately underlies the
Cenomanian, and typical sandstones nowhere reappear
higher in the section. A typical succession for this Northern
type is displayed in the plateau-edge of Gebel Gunna, in Eastern
Sinai, as follows :—

Thickness in metres.
(Top.) 1. Ferruginous limestones. Some of these beds contain

traces of diademoid sea-urchins, and suggest a parallelism

with the Lower Senonian beds near Wadi Qena subsequently

GESCRID CO Soo. 5 och REPRE ore cc h kane 2 ono eee ee ce 61
. Limestones or green marls containing LHchinobrissus humet

Fourtau, and Cyphosoma aff. majus Cog. : the presence of the

latter points to these beds being still of Turonian age.

3. Bivalve-cast limestone.

4. Ostrea-olisiponensis Limestone, associated with Ostrea rowviller
Coq.

}. Users marls containing Periaster oblongus Dune., Tylostoma
elatius Coq., and Heterodiadema libycum Cott. Also numerous

to

sea-urchins described by Brot.d. W. Gregory? -o. . ns. eee 3°5
6. Loose sandstone and marls, containing large specimens of Ostrea

olistponensis Sharpe in Sbuudance..........5 20... 14
7. White grits of the Nubian Sandstone, calcareous in the upper

MOSMEETES % 255.5: cone eee eae Cioass «nance oe Jcten a eee eae 200

The typical Cenomanian beds in this section have not been
recognized in the Abu Roash district; but that area may still be
retained in the northern division, owing to the great development
of Turonian, Senonian, and Danian limestones.” In Baharia,
on the other hand, the fossiliferous Cenomanian strata with charac-
teristic oysters and sea-urchins are well-developed; but the
Turonian and Senonian formations are not so clearly marked as
elsewhere, or lie in regions more difficult of study.’

(B) The Cretaceous Strata of the Wadi Qena Area.

During the season of 1910, a very interesting region was explored
at the head of Wadi Qena, in the Eastern Desert of Eg gypt—the
study revealing an unexpected transitional phase, characterized by
alternations of sandstones and Upper Cretaceous limestones.

1 Geol. Mag. dec. 5, vol. iii (1906) pp. 216-27 & pls. x-xi.

sla ea ea Beadnell, Egypt. Geol. Surv. Report (1900) pt. ii, “The Creta-
ceous Region of Abu Roash,’ 1902, in which reference will also be found to
the work “of other authors in this area.

3 See J. Ball & H. J. L. Beadnell, Egypt. Geol. Surv. Memoir on Baharia
Oasis, 1903.

Vol. 67. | DURING THE CRETACEOUS AND EOCENE PERIODS. 121

Alternation of Sandstones and Upper Cretaceous
Limestones.

Wadi Qena is a wide expanse, bounded on the west by the
precipitous cliffs of the limestone plateau, which has its western
termination in the scarps bordering the Nile Valley. On the east,
in sharp contrast with the uniform flat-topped rock-wall of the lime-
stone plateau, are the serrated and multi-coloured granitic peaks or
the more monotonous greenish dioritic, volcanic, and metamorphic
members of the Red Sea Hills, while between them lie broad plains,
out of which rise brown tabular outliers of Nubian Sandstone.

Between the main drainage-line of Wadi Qena (which itself is
relatively rich in vegetation) and the western scarp is a confused
country of low hills, terminating towards the valley in a secondary
well-marked cliff varying from 50 to 150 metres in height.

Until last year (1910) this country had not been geologically
examined ; but, although details still require elucidation, the broad
features are clearly revealed. It owes its present character to a
conformable succession of Cretaceous strata dipping on an average
3° westwards (varying from south-west to north-west), which are
probably some 300 metres thick. They are especially well developed
in the watershed region at the head of Wadi Qena, where three
great drainage-systems meet, one of the sections studied being in
Wadi Hemaiet, which descends from the limestone plateau to Wadi
Qena, and thus to the Nile at the town of Qena; a second section
in Wadi Abu Had, which, rising near the head of Um Hemaiet,
descends rapidly to the Gulf of Suez; while the third section was
exposed in the low hills separating Wadi Hawashia from Wadi
Tarfa, the latter being a great drainage-line which joins the Nile
not far from Minia.

The most important feature in these sections is the threefold
repetition of strata typical of the Nubian Sandstone, between beds
the fossil contents of which definitely fix their age: so that we may
here speak of an Upper, a Middle, and a Lower Nubian Sandstone,
the two first-named from their associations being indubitably Upper
Cretaceous, while the lower division is not readily separable from
the Cenomanian strata which it underlies. The most notable divi-
sions recognized may be thus summarized :—

The highest beds of the series are displayed in the precipitous
cliff-face which forms the eastern termination of the great lime-
stone plateau east of the Nile. These were recorded as members
of the Nummulitic Series by Dr. G. Schweinfurth,’ but the ascents
made on these somewhat dangerous scarps show them to be com-
posed in their upper part of

1, A white limestone weathering to a biscuit colour, and containing broad

tabular bands of flint or large isolated concretions (an example
measured 60 x40 em.) of the same material. This is underlain by

? Dr. Schweinfurth has published an excellent series of topographical maps
with geological notes, embracing most of the Eastern Desert north of 26° N.,
and issued by Dietrich Reimer, 29 Wilhelmstrasse, Berlin.

122 DR. W.F. HUME ON SECULAR OSCILLATION IN EGYPT [Feb. 1911,

2. A white limestone of similar lithological character, but without flints.
In its lower portions are isolated bands of Ostrea vesicularis Goldf.
and numerous scattered examples of Pecten farafrensis Zitt. (P. mayer-
eymart Newt.).

The presence of a Terebratulina, though rare, is further evidence of the
Danian age of this deposit, as the form resembles the species occurring in the
Danian of the Oases. Aggregates of cubical pyrite altered to limonite and stem-
like concretions of iron oxide are frequently present ; but, as a whole, the series
is throughout of great lithological similarity, and very poor in fossils, At the
extreme base of these strata is a band rich in Ostrea vesicularis var. judaica,
which attains a large size.

3. Immediately beneath the Vesicularis Beds is a succession of grey-
tinted strata, about 3 metres thick, characterized by an abundance of
sharks’ teeth, vertebra, etc., especially Otodus auriculatus Ag. and
Corax pristodontus Ag. Specimens brought from this bed have
been analysed, and yielded over 20 per cent. of tricalcic phosphate.
Associated with them are large specimens of Plicatula, and imme-
diately below them comes a band containing an oyster which. has
ailinities with O. nicaisei.! These probably correspond with the Cam-
panian farther south,

4. Underlying these are the uppermost beds of the detrital series, consisting
of well-banded green shales, alternating with beds of dark clay con-
taining rock-salt or brown phosphate-layers, the whole resting upon
flagey sandstones.

This Upper Nubian Sandstone and Shale is of geographical
importance, as it is more rapidly eroded than the Danian Lime-
stones on the west and the Santonian Beds on the east, resulting in
the production of an easily-traversed shallow depression at the
heads of Wadi Hemaiet and Wadi Abu Had. A notable feature in
this region is the steep local westward dip of the sandstones, angles
of from 23° to 35° having been noted. Farther east the strata are
horizontal, no ready explanation of these phenomena having been
obtained during the time available for study.

These three divisions (2, 3, & 4) can be traced northwards to whe
southern scarp of the Galala Hills; but, in the low country where
the great drainage-systems of Wadis Qena, Tarfa, and Hawashia
have their origin, denudation of the softer members has initiated
the broad valley-depressions in which they take their rise. ;

Owing to the rapid traverses necessitated by the waterless
character of the district west of Wadi Qena, it has not been
possible to make a detailed examination of the low country east of
the Upper Nubian Sandstone; but, in some conspicuous ridges
developed in eastward succession to this sandstone formation, a
further series has been recognized, consisting of :—

5. Calcareous sandstone in slabs 2 inches thick, resting on 5 inclfes of
yellow sands. At the base these contain ferruginous concretions,
oysters of the acutirosiris type, Plicatula, Tylostoma, and bivalve-
casts, the assemblage haying a strong Santonian aspect.

6. A new facies underlies these strata, a normal succession of: flaggy
yellow sandstones and ferruginous quartzites, typical of the Nubian

1 IT have to thank M. R. Fourtau for much valuable help in the identification
of the oysters, sea-urchins, and ammonites obtained in the Wadi Qena area
and other localities examined by me.

Vol. 67.] DURING THE CRETACEOUS AND EOCENE PERIODS. 123.

Sandstone, these being underlain by an alternating series of sand-
stones (jointed in large blocks), limestones, and thin greensand bands,
the limestones containing diademoid sea-urchins (like Rachiosoma)
and intermediate bivalves. Farther north, at the head of Wadi
Abu Had and Wadi Tarfa, these strata contain enormous numbers of
Nucleolites, in Abu Had associated with the diademoid form. Near
the watershed of Tarfa and Hawashia, they immediately overlie a
thick series of sandstone (flaggy, fine-grained, white varieties and red
ferruginous layers alternating), which in its turn rests upon green
shales, ‘This typical Nubian succession is probably at least 50 metres
thick, and Holectypus turonensis is found in the uppermost portion
of these sandstones; in the green shales below them sharks’ teeth
(Scaphorhynchus) are present.

7. This great mass of Middle Nubian Sandstone (for there is no
difference in its character from that of the typical Nubian Sandstone
farther south) forms conspicuous secondary ridges to the west of
Wadi Qena, and in part determines the watershed between the
Hawashia and Tarfa drainages. Its age is left in no doubt, as it
immediately overlies 0

8. The limestones rich in ammonites, which are present in vast numbers
in many localities south of the Galala Hills: these ammonites,
which often attain a large size, are mainly species of Hemitissotzu and
Pseudotissotia. Though not of great thickness, indeed rarely exceeding
2 metres, these limestones are of importance, as they have such marked
Lower Turonian characteristics.

9. They immediately overlie the Cenomanian Series, already well known
from the researches of Schweinfurth and Zittel; the strata appear
in a series of zones, which, due to the comparatively steep dip, form a
succession of broad bands, and give rise to characteristic scarps or
plains. The most conspicuous of these are thick limestones, almost
entirely composed of Ostrea olisiponensis Sharpe, and forming a
well-marked low scarp wherever present. Underlying them are the
following in regular succession :

10. An Ostrea-flabellata Zone, with Hemiaster pseudofourneli P. & G., Venus
reynest Coq., ete.

11. Ostrea-africana Zone, with Neolobites fourtaui Perv. and N. schwein-
Jurthi Wek.

12. Ostrea-suborbiculata Zone, in which this oyster is present in vast
quantities,

These Cenomanian strata form the summit of the high cliff (150
metres) which bounds Wadi Qena on the west, and immediately
overlie the white friable sandstone (13), the Lower Nubian
Sandstone, which is highly calcareous in its upper portion, and
contains well-rounded quartz-pebbles sparsely distributed through
it. The beds at the base of the cliff are lithologically very similar
to those at the summit, there being no evidence that any portion of
the sandstone is of earlier date than the period of the Cenomanian
advance of the sea. It may, therefore, be stated with some degree
of certainty that, apart from the Carboniferous sandstones of
Northern Egypt and Sinai, the great mass of the Nubian Sand-
stone hitherto studied was formed during the Cretaceous depression,
and in the Wadi Qena area was a distinct marine deposit, repre-
senting temporary increase of activity in the accumulation of
detrital materials, due either to climatic or to tectonic changes.

124 DR. W. F. HUME ON SECULAR OSCILLATION IN EGyPr [Feb. 1911,

III. Tae Hammama Tyrer.

South of latitude 27° 15' N. avery marked change is apparent
in the character of the Cretaceous strata, the denudation which has
taken place in the lower portion of Wadi Qena having, however,
removed all traces of the stages in the process. In the section
developed in Gebel Abu Had, 25 miles north-east of Qena, only the
Danian and Campanian beds are present as fossiliferous strata,
and these immediately overlie the Nubian Sandstones, in which no
fossil-bearing layers have been noted. A typical section in Wadi
Hammama, 25 miles east-north-east of Qena, is as follows :—

Thickness in metres.

Top. Le: Biseuit=coloured limestone «..0.00.. .sc35.. ee
2. Green shales
DANIAN nie ae it 2 OE OS a aid ime OTE OOOO, 7c SY sbetehernis Oy
3. Yellow limestones and Pecten-farafrensis' or

Ptmayer=eymart Marls’......<3..0320leeiee ae

Campanian... 4. Hard bluish crystalline limestone with many
cephalopoda (Ptychoceras sp., Anisoceras sp.,
and SBaculites syriacus Conr.): elsewhere,
as near Qosseir, represented by beds with
Trigonoarca multidentata R. B. Newton and
Ostrea villet.

5. Bone-bed containing many teeth of Otodus auri-

culatus Ag., Galeocerdo sp. -
6. Oyster-limestone.

These Danian and Campanian strata, as shown in the Egyptian
Geological Survey Memoir on the Eastern Desert (by T. Barron
& W. F. Hume, 1902), are very widely distributed in the area
between the Nile Valley and the Red Sea, from latitudes 25° to
28° N. They form part of a Cretaceous facies, which is in addition
characterized by the total absence of fossiliferous Turonian and
Cenomanian members.

TV. Tae Danian Extension 1n Eastern Eeypr.

A further change in Cretaceous characteristics from north to
south is displayed by the Danian strata, which I have now examined
over wide areas from the Southern Galala Hills to Kharga Oasis. In
the region bounding Wadi Qena this series consists of a vast
thickness of white chalk, which is remarkably unfossiliferous in
its higher portions. Near the base are scattered individuals of
Ostrea vesicularis Goldf., Pecten farafrensis Zitt. (P. mayer-eymari,
R. B. Newt.) being also irregularly distributed. The only other
fossils noted were small Baculites and Terebratulina. At the ex-
treme base is a layer composed of a large form of Ostrea vesicularis
var. judaica, which is present at times in greati numbers. Very

1 See M. Blanckenhorn, ‘Neues zur Geologie & Palaontologie A’gyptens ’
Zeitschr. Deutsch. Geol. Gesellsch. vol. lii (1900) p. 411; and J. Wanner,
Paleontographiea, vol. xxx (1902) p. 114 & pl. xvii, figs. 1-3. Compare with
R. B. Newton (P. mayer-eymari), Geol. Mag. dec. 4, vol. v (1898) p. 535.

Vol. 67.] DURING THE CRETACEOUS AND EOCENE PERIODS, 125

different is the fauna of the Danian in the Western Oases, where
Zittel recognized three well-marked divisions :—

(a) Snow-white well-bedded limestones or earthy chalk.
(6) Greenish and ashen-grey paper-shales.
(c) Beds with Lxogyra overwegi Buch.

These beds are characterized by a fauna consisting of small
gasteropoda, bivalves, corals, crinoids, etc., replaced in iron oxide,
which have been made familiar to all students of this subject in
the works of Quaas and Wanner, based on Zittel’s collected materials.
The side-issue as to the age of the Pecten Beds had been settled
by Dr. Blanckenhorn’s recognition of the Pecten (named P. mayer-
eymart by Mr. R. Bullen Newton) as being identical with the P.
farafrensis of Zittel, but certain difficulties still existed in
regard to their correlation with the Danian beds of Western Egypt.
Delanoue! had obtained a rich fauna in the grey paper-shales
31 metres thick, which underlie the Eocene limestone at Thebes,
foraminifera and ostracods being abundant; while, among the larger
forms, d’Archiae recognized numerous gasteropoda (Pusus, Triton,
Cerithium, Natica), cephalopoda (Atura ziczac Sow., Nautilus:
centralis Sow., and N. delanouer d’Archiac), dimyarian bivalves.
(Nucula, Leda, Lucina, Neera), and brachiopoda such as Terebratu-
lina tenwstriata (Leym.). This assemblage, regarded as recalling
the fauna of the London Clay, led to the inclusion of the shales in
the Eocene.

During his visit to Egypt, Zittel extended his researches to the
eastern side of the Nile, and called attention to the importance of a
layer rich in Cretaceous oysters conspicuously developed near Edfu.
These he regarded as the equivalent of his Hvogyra Beds in Kharga
Oasis, etc., and remarked that, if this were the case, between it and
the Lower Eocene should be a thick complex of ashen-grey or green
paper-shales, and above these a white chalky limestone.

The shales were noted by him on the right shore of the Nile near
Esna, where they underlay the snow-white Lower Eocene Operculina
Limestone, Dr. Schweinfurth also noting them at the base of the
Eocene escarpment on both Nile banks. Zittel remarked, however,
that neither he nor Dr. Schweinfurth had been successful in finding
fossils in them, adding :

‘If these paper-shales of Esneh correspond with those of Khargeh and
Dakhel, then the uppermost white Cretaceous limestone with Ananchytes
ovata is either wanting at Esneh, or does not contain any fossi!s and cannot

thus be distinguished from the petrographically similar Eocene limestone of
the Libyan stage,’

the latter alternative being considered the more probable.”

1 ©. R. Acad. Sci. Paris, vol. Ixvii (1868) pp. 704-707.

2 « Beitrage zur Geologie & Palaontologie der Libyschen Wiiste’ Palxon-
tographica, vol. xxx, pt. i (1883) p. Ixxviii. Dr. G. Schweinfurth, in Peter-
mann’s Mitteilungen, vol. xlvii (1901) p. 6, regarded the paper-shales at Esna
and Sharawna as of Eocene age, following the opinion then held by most
writers. See also R. Fourtau, Bull. Soc. Géol. France, ser. 3, vol. xxvii (1899)
p. 481.

126 DR. W. F. HUME ON SECULAR OSCILLATION IN EGyetT [| Feb. 1911,

Dr. Blaneckenhorn made a considerable advance when visiting
Luxor in 1902, by finding a small fauna in the shales between the
temples of Deir el Bahari and Deir el Medina, in which Dr. Oppen-
heim recognized thirteen species identical with those occurring
in the Cretaceous beds of the Oases, including so characteristic a
species as Cinulia ptahis (Wann.). ‘Two species also agreed with
forms from the Chalk of Siegsdorf in Southern Bavaria; and the
eephalopod originally named Aturia ziczac, which had been so
helpful in complicating the problem by its strong Eocene affinities,
was regarded as really a precursor of that species and named by
Oppenheim Aturia preziczac. Mr. Beadnell* later re-examined the
eastern bank of the Nile, and was enabled to arrive at broad con-
clusions with regard to the Cretaceous age of the Esna Shales, aud
the relations of those beds to the White Chalk. Hitherto, however,
the relations of the Oases Danian fauna to the Pecten Beds of the
Eastern Desert had not been precisely determined. During the spring
of 1905, when examining the geology of the Eastern Nile Valley
border between Esna and Aswan, I was enabled to obtain satis-
factory evidence of their relations and of the Upper Cretaceous
succession in this portion of the country, obtaining some valuable
evidence in addition to that already recorded by Mr. Beadnell (op.
cit., table on p. 675).

The strata in question are well exposed in the shallow valleys to
the east of Kilabia, on the eastern bank of the Nile south of Esna,
where the following succession is clearly displayed :—

(Top.) 1. The summits of the hills are covered with a biscuit-coloured
limestone containing abundant Lower Eocene fossils, notably Cono-
clypeus delanouer de Lor., Rhabdocidaris libyensis Gregory, and
Linthia cavernosa de Lor. Operculina libyca Schwager sometimes
forms the main mass of the rock.

2. An upper series of shales, the Esna Shales, in which fossils are
rare, corals similar to those mentioned below (p. 127) being, however,
obtained on several occasions.

3. White Limestone or Chalk weathering pink, which contains
very poor specimens of Ostrea vesicularis. The absence of distinctive
fossils has been a cause of difficulty: and, after a most careful search
by several observers, the fauna remains remarkably poor, being limited
to Echinocorys vulgaris Leske (found by Mr. Beadnell at Fares, on
the western bank of the Nile near Kom Ombo, but searched for in
vain by both of us on the eastern side); Ostrea vesicularis (from
various localities); Ventriculites of large size (on the shore at
Ragama, Kom Ombo plain); and Sehizorhabdus libycus (found by
Dr. Schweinfurth and Mr. Beadnell near Ragama, and by myself
on the summit of the white limestone in the hills west of Esna).
Despite its poverty, the fauna is evidently that of the White Chalk of
the Oases, and the limestone of Kilabia and Kom Ombo is therefore
the Eastern equivaient of that formation.

4, Shales underlying the White Limestone.—When examining
the Kilabia section, I obtained an abundant Danian fauna which is

1 «Relations of the Hocene & Cretaceous Systems in the Hsna-Aswan Reach
of the Nile Valley’ Q. J. G. S. vol. lxi (1905) pp. 667-78.

Vol. 67.| DURING THE CRETACEOUS AND EOCENE PERIODS, 127

practically identical with the series recorded from the ashen-grey
paper-shales of the larger Oases, and described in the valuable works
of Wanner and Quaas.?

List oF DANIAN Srecres FROM KILABIA,.

Caryosmilia granosa Wann. | apyy- Avellana cretacea Quaas.

Palgopsammia multiformis ue Volutolithes desertorum Quaas.
Wann. ices Volutolithes sp.

Cyphosomoid form. Minute. Fasciolaria (Odontofusus) rohlfsi.

Pentacrinus sp. Alaria schweinfurthi Quaas. Very

Terebratula ct. libyca. common.

Terebratulina chrysalis Schloth. Alaria sp.

Leda leia Wann. Very common. Nautilus desertorum Zitt.

Nucula sp. Very common. Baculites sp.

Scalaria desertorum Wann. Odontaspis sp.

Cerithium abietiforme Wann.

This fauna is almost absolutely identical with that of the ashen-grey clays
of the Southern Oases: on the other hand, there are certain differences when
it is compared with the Luxor series. The comparison shows a difference as
regards the corals, Caryosmilia granosa and Palgopsammia multiformis being
both unrecorded at Luxor, where Palgopsammia zitteli Wann. and Pattalo-
phyllia egyptiaca (Wann.) take their place; the absence of Alaria schwein-
furthi, one of the commonest of the Kilabia forms, is also a noticeable feature,
while the most prominent member of the upper shales present at Luxor, the
Aturia now named preziczac by Oppenheim, was sought for in vain in the
district east of Esna. It is at present premature to say whether these
differences are local, but the Atwria certainly seems to be restricted to the
upper portion of the Esna Shales.

5. Pecten Limestones.—A second band of marly limestone underlying
these ashen-grey shales is characterized by the abundance of Pecten
mayer-eymari Newt. (P. farafrensis Zitt.) and presumably is equivalent
to the Pecten Marls above-mentioned.

6. Shales similar to those of No. 4 underlie the marls, but were not well
exposed where examined.

7. Cephalopod Bed.—There is evidence of the existence of this bed
beneath the shales, as several species of Scaphites allied to Sc. kam-
bysis Zitt. were found on a plateau south of the escarpment in which
Beds 1 to 6 are best developed. This stratum probably is closely
associated with

8. The Oyster-Bed and Phosphatiec Series, which are practically
the most prominent members in the lower country between Sharawna
and Mahamid—the oysters having given rise to a very hard limestone,
which has determined the well-marked plateau succeeding the con-
spicuous white hill-ranges wherein the limestones and shales are
displayed. The oysters are typically Campanian, including as prin-
cipal members Ostrea forgemolli Cog. and O. villei. Closely associated
with the oyster-layers, and generally underlying them in the typical
sections, is a phosphatic layer containing abundant fish-teeth, among
which those of Otodus bsauriculatus Zitt. are conspicuous.

1 The succession obtained during my studies is here given in view of the
discovery of this fauna, otherwise the results of my expedition agree very
closely with those of Mr. Beadnell. The chief point on which we differ is
where he regards the Esna Shales as passage-beds, his view being based on
observations made in Farafra Oasis, a locality which I have not had an oppor-
tunity of studying. In his paper he does not state whether he obtained the
typical small gasteropod fauna in the shales recorded above the Operculina
Beds.

128 DR. W.F. HUME ON SECULAR OSCILLATION IN EGyPT [Feb. lati,

9. In many cases these lower members of the fossiliferous Cretaceous
series are underlain by further greenish-coloured shales, or may be
immediately succeeded by the uppermost layers of the Nubian
Sandstone.

Before proceeding to consider the latter, the general conclusions.
as to this interesting Cretaceous series may be summarized.

Tts age.—The following table shows better than words the
relations of this fossiliferous series to the strata of similar age both
on the west and on the north.

OASES. Esna District. ' Hast or Qena.
Lower Libyan Limestone. Lower Libyan Lime- Lower Libyan Limestone.
stone.
Upper Shales. Upper Esna Shales. White marly beds. \
Upper Hsna Beds.
White Chalk. White Chalk. Marly limestone.
Ashen-grey Paper-shales. Lower Esna Shales. Greenish shales.

Lower Hsna Beds.
Pecten Marls and White marly limestone
Shales. with Pecten.
Exogyra-overwegi Beds. Cephalopod Bed. } Ptychoceras Bed.
Oyster Limestone. Coprolite Bed.
Coprolite Bed. Oyster Limestone.

An examination of the foregoing table shows a broad general
resemblance between the series in the three localities, and there
cannot be the slightest hesitation in agreeing with Mr. Beadnell,
in regarding the beds from the summit of the White Chalk to the
base of the Pecten Marls as of Danian age. Indeed, I should be
inclined to admit the Upper Esna Shales into the same category,
such forms as have been found in these strata resembling those
of the underlying shales, and having no connexion with the beds
containing the varied Kocene fauna, rich in echinoderms and
Operculinz, which immediately overlie them.

On the other hand, all writers on this subject seem to be agreed
that the Cephalopod and Oyster Beds are of Campanian age, and
so the controversy with regard to the Cretaceous age of the whole
series appears to be settled.

The important changes noted, passing from north to south, are
therefore :

(1) In the regions north of latitude 26° N., the Danian White Chalk is
mainly unfossiliferous, except for scattered Pectens and oysters. The
rich coralline and bivalve fauna of the Oases has never been observed,
and shales are absent in the series.

(2) In contrast, the Danian Series of the Oases is composed of both
shales and white limestones: these contain small corals, univalves, and
bivalves, and consequently they probably indicate shallower-water con-
ditions than are exhibited farther to the north-east, where such life as
existed was micro-organic. :

(3) In the neighbourhood of Hsna the Western and Eastern Danian
types are co-existent and closely related.

The third Cretaceous facies occupying the greater part of Southern
Egypt is thus divisible into an Eastern and a Western division,

Vol: 67.) DURING THE CRETACEOUS AND EOCENE PERIODS. 129

according to the nature of the Danian White Chalk and the
presence or absence of shales. Its other general features are the
great development of phosphatic beds in the Campanian Series and
the complete dominance of sandstone during the Cenomanian and
Turonian epochs, no fossiliferous strata of these ages having been
recorded south of latitude 27° N. This phosphatic Cretaceous
belt sweeps from the hills near Gebel Zeit in a southerly and
south-westerly direction, crossing the Nile between Esna and Edfu,
and reappearing in the northern portions of Kharga and Dakhla
Oases.

V. Tur Sournern Cretaceous Typr.

A fourth facies was recognized during my expedition of 1908 in
the extreme southern portions of Egypt: especially at the Oasis
of Dungul, near Kurkur Oasis, and on the great Arbain road
south of Kharga. In these regions the Danian strata are, in the
main, a compact white limestone containing simple corals of the
Celosmilia type, while the shales play a subordinate part. The
most noticeable change is in the character of the Campanian strata,
which, instead of being phosphatic or fish-bearing, are characterized
by a remarkable development of small sea-urchins, large Turritelle,
and a great variety of univalves recalling the Red Sea fauna of
the present day. They are noticeable for their marked yellowness,
and are a conspicuous feature wherever observed. ‘The sea-urchins
which I collected have been recently described by M. R. Fourtau?
under the names of Dorocedaris chercherensis (op. cit. p. 96),
Bothriopyqus schweinfurtht (from Dungul, p. 104), and Gito-
lampas fallax (from Dungul and Um Shersher, pp. 107-15), the
last-named being extraordinarily abundant at Um Shersher, on the:
Arbain road.

VI. Summary or Cretacrous History in Eeyrt.

We are now able to trace the sequence of Cretaceous history in
Egypt, both by modifications in the stratigraphical series and by
variation in its lateral distribution. Five phases are recognizable,
exclusive of those noted in Syria, where the whole of the Upper
Cretaceous appears to be represented by limestone. The five phases
are as follows :—

(1) The North Egyptian type, in which the whole of the
beds, from the Danian to Cengmanian, are represented by lime-
stones ; while the Cenomanian marls and limestones are highly
fossiliferous, Hemzaster sp. and various exogyroid forms of oysters
being dominant. The Nubian Sandstone is, in its entirety, older
than the Cenomanian.

(2) The Wadi Qena type, in which the Upper Cretaceous
series is subdivided by bands of sandstone, presenting features
regarded as characteristic of the Nubian Sandstone. The Danian

1 ‘Description des Echinides fossiles’ Mém. Inst. Egypt. vol. vi, fase. ii,
December 1909.

Q. J.G.S. No. 265. é

130 DR. W. F. HUME ON SECULAR OSCILLATION IN EGYPT [Feb. 1911,

is typically white chalk throughout, with scattered specimens of
Pecten farafrensis (P. mayer-eymar’) and Ostrea vesicularis var.
judaica in abundance at the base. The Campanian is phosphatic.
The best-marked sandstone-bands occur between the Campanian
and the Santonian, immediately overlying the Turonian, and at
the base of the fossiliferous Cenomanian. The Upper Nubian
Sandstone beds have well-marked green and red shales associated
with them.

This series may itself be subdivided into two sub-types: (a) the
Hawashian (from Wadi Hawashia), in which ammonites of the
Tissotia group are strongly developed in the Turonian strata ; and
(6) the Um Hemaiet sub-type, in which ammonites are absent,
and the Turonian, as such, is not markedly developed.

(3) The Hammama type, so named from Wadi Hammama,
in which these strata were first recorded by the late Mr. Barron
and myself. This type also includes the Campanian strata which
had been previously studied by Prof. E. Fraas on the Qena-Qosseir
road. The characteristics are: partial replacement of Danian white
chalk by the green and red Esna Shales and by Pecten-farafrensis
(P. mayer-eymari) Marls, the white limestones forming incon-
spicuous bands. The Campanian beds are still phosphatic, but
the Turonian and the Cenomanian are no longer represented, the
strata of those ages in this position being sandstones, with the ex-
ception of the (bituminous) Abu Rahal Lingula Shales. These
are at present a local occurrence, for which no parallel has been
found elsewhere.

(4) The Oasis type, in which the Danian shales are rich in
corals and small univalves, and the white limestone is characterized
by the presence of Echinocorys, Pentacrinus, and a single coral
recalling those of the White Chalk in North-Western Europe. As.
in No. 3, the Campanian is phosphatic, and the Nubian Sandstone
commences immediately below the oyster-beds of that formation.

(5) The Dungul type, in which the Danian shales are less
marked, while the hard subcrystalline limestones contain single
corals widely distributed. The Campanian beds are no longer
phosphatic, the corresponding strata being very rich in sea-urchins
and univalves. The Nubian Sandstone commences immediately
below the oyster-zone of this series.

The varying characters of the above-mentioned five types clearly
illustrate the gradual advance of the sea over Egypt during Upper
Cretaceous times, the invasion having commenced earlier in North-
Eastern Egypt, and the transition being marked by the relative
distribution of the sandstones, clays, and limestones, both in time
and in space. Among the most interesting features are the faunal
enrichment of the Danian limestones in the south-west, probably due
to their deposition in shallower waters; the change from phosphatic
conditions to abundant sea-urchin and univalve life in the same
direction; the prevalence of limestone in the north, of sandstone
in the south, and of an alternating series of limestones and
sandstones in the centre of Egypt.

Vol. 67. ] DURING THE CRETACEOUS AND EOCENE PERIODS, 131

VII. TRANSITION FROM THE CRETACEOUS TO THE
Eocrnet PERIOD.

The gradual advance of the Cretaceous sea over the greater part
of Egypt having thus been proved in a very conviucing manner,
we have next to enquire what were the changes which led to the
remarkable dissimilarity between the Eocene and the Cretaceous
faunas. Egypt has long been regarded as a striking illustration
of lithological continuity, when the strata formed during the two
periods are compared ; but close study of the two formations reveals
some suggestive differences in the relations existing between them
in various parts of the country.

In the South of Egypt the junction between Eocene and Cretaceous
appears in two different forms. In the first, or Luxor type, the
shales containing a typical fauna of small gasteropoda, pelecypoda,
etc. presenting a Danian character, are separated by only a few metres
of a white chalk (weathering to a biscuit colour) from more massive
Eocene limestones containing large forms of Rhabdocidaris, Linthia,
and Lucina thebaica Zittel.

In many localities these strata are characterized by the presence
of Operculina libyca Schwager, which sometimes forms almost
the entire mass of the hmestone. In such places the nature of the
transition is not very evident, and the marked paleontological
hiatus is not accompanied by very sharp lithological differentiation.
In the limestone-plateau north-west of Qena the conditions are
remarkably different. There, at the base of the cliff facing Wadi
Qena on the west, are a series of fine-grained, well-stratified, chalky
limestones containing Pecten farafrensis Zitt., Ostrea vesicularis
Goldf., Terebratulina sp. (?)," and other typical Danian fossils.
These pass, so far as can be judged, into limestones of precisely similar
lithological character, yet revealing no trace of fossils; their
honeycombing, close-set stratification, and jointing give them the
appearance of having been formed under intense current-action
rather than of having been deposited in the waters of a quiet sea.
These strata are of great thickness, over 100 metres (300 to 400 feet
thick), and the typical Nummulites of the Kocene only appear where
more massive limestones overlie these softer beds.

On the north the differences become further emphasized, there
being marked unconformity between the Eocene and the Cretaceous
strata where these are in contact. A notable and familiar instance
is the unconformable junction of the Middle Eocene beds with
the Cretaceous at Abu Roash, near the Pyramids, described by
Mr. Beadnell.* Here the Carolia Beds of the Upper Mogattam
division of the Middle Eocene rest on the Danian limestones to the
west; while near the Pyramids the Lower Mogattam (Nummulites-
gizehensis) Beds occupy this position, suggesting overlap on a

1 The Terebratulina needs further study.
* H. J. L. Beadnell, ‘The Cretaceous Region of Abu Roash’ 1902, Egypt.
Geol. Surv. Report (1900) pp. 14-17 & pls. vii-viii.
K 2

132 DR. W.F. HUME ON SECULAR OSCILLATION IN EGYPT | Feb. 1921,

Cretaceous insular area. Still more remarkable is the unconformity
which has come under my notice in the Southern Galala Hills,
where the lower slopes consist of a well-stratified series of white
chalk beds weathering to a biscuit colour. Immediately overiying
these was a highly fossiliferous stratum, the fauna of which has
been identified by M. Fourtau as Lower Moqattam or Middle Eocene
in age, so that the whole of the Libyan strata (commonly classed
as Lower Eocene) are entirely absent. These beds are in their
turn apparently succeeded by conformable subcrystalline lime-
stones, which in many cases are true marbles. Only
many miles away to the west, near Gebel Shaira, do these contain
the slightest trace of fossils, those obtained being Nummulites gizeh-
ensis de la Harpe, and large specimens of Velates schmiedeli Chemn.,
present in a crystalline matrix.

Any theory of the relations between the Cretaceous and the
Eocene Periods must take account of three essential factors :—

(1) The slight change in lithology, but marked difference in fossil contents
exhibited in the South of Egypt.

(2) The striking resemblance in petrographical character, but difference
in physical structure, suggesting current-bedding, exhibited in Central
Egypt.

(3) The existence of marked unconformities between the two formations
in Northern Egypt.

Incidentally, two other factors have to be considered: these are :—

(4) The prevalence of subcrystalline limestones at the summit of the Cre-
taceous or the base of the Eocene, where these meet ; and

(5) Volcanic activity, which is particularly well marked at the close of
the Eocene Period.

We have seen that, during the Upper Cretaceous Period, there is
strong evidence for the gradual advance of a wide-spreading sea
over the whole of this portion of Africa, organic deposits gradually
becoming preponderant over those of detrital origin. Examination
of the Hocene and Cretaceous areas in the outer deserts has already
revealed that the tectonic relations are not so simple as had been
generally supposed, but that closer mapping will probably indicate
a marked if gentle folding—the long axes of which have an east-
ward and westward tendency. ‘The exact extent and magnitude of
such foldings can only be determined by accurate levelling, but the
Abu Roash-Mogattam anticlinal system and the Wadi-Araba anti-
cline in the north find a counterpart farther south in the well-
marked anticlines near the head of Wadi Qena, and in the hills
south-east of the Qena bend of the Nile. It is a fair inference that
such folds were the first cause of the great change so universally
noted, the first basis of the new Tertiary world.

‘The anticlines or domes would give rise to islands or submarine
ridges where erosion would be active, while the basins would form
centres within the areas of which the denuded materials could be
deposited. As the Danian limestones were widely distributed, the

Vol. 67.] DURING THE CRETACEOUS AND EOCENE PERIODS. 133

first Eocene beds in the synclines would be re-assorted and current-
affected rocks of the same lithological constitution; while the
worn-down summits of the domes would be the surfaces upon
which the new Eocene fauna of nummulites and Operculines, or
in the shallower portions, of large sea-urchins and bivalves, would
flourish. Should the views here stated be in accordance with the
true course of history at this period, it might be possible eventually
to map out the original domes and basins of the transition, and
trace (just as has been done in the previous pages for the Cretaceous
advance) the gradual gain of land from sea in the Eocene Period,
by fold effects, in which the flexures occurring in the deepest-water
area, namely, Northern Egypt, are the most pronounced, and conse-
quently would be unconformably overlain by the youngest Eocene
beds. In the shallow basins between the folds the easily denuded
members would first be redeposited, and then the Eocene life would
be developed in normal zonal succession according to principles which
are as yet very obscure.

VIII. Tur Favwnat History or Eayer purine Eocent Times.

Offering this theoretical suggestion for consideration to explain
the differing character of the strata immediately overlying the
well-determined Cretaceous series, and leaving the unfossiliferous
‘remade’ white limestones as a problem for special study, 1 may
next direct attention to some of the marked zonal variations ob-
served in the stratigraphical succession during the Eocene Period.
The change is at once marked by the incoming of the Tertiary
foraminifera (Operculina lybica Schwag., Nummulites variolarius
Lam., and JV. curvispira Men.): the Operculines being present in
vast numbers in the lowest zone, from the Nile Valley to the
Southern Oases. Closely associated with these are strata rich in
well-developed sea-urchins ( Conoclypeus delanouet de Lor., Rhabdo-
eidaris libyensis Greg., Linthia cavernosa de Lor., etc.) and large
bivalves (Lucina thebaica Zitt.), there being among the larger
invertebrates as marked a dominance of sea-urchins and oysters as
in the Egyptian Cretaceous. Brachiopoda, on the other hand, are
almost absent in both.

The beds forming the lowest Eocene strata in Egypt, termed
‘Lower and Upper Libyan’ by Zittel, are enormously developed,
extending in the Nile Valley from north of Minia to the faulted
belt near Kom Ombo.

In the Western Desert they extend to Dungul in lat. 23° 30’ N.,
and from the eastern or northern boundaries of the principal oases,
namely: Kharga, Dakhla, Farafra, and Baharia. In the Eastern
Desert of Egypt the Lower Libyan Series is equally developed, being
an important constituent in the broad limestone-plateau which
extends from the Nile and Wadi Qena and from the Galala Hills,
and being also present in the faulted outliers near Qosseir.
Well-defined subdivisions of these strata are not easily deter-
minable, owing partly to the inaccessible nature of the regions in

1384 DR. W. F. HUME ON SECULAR OSCILLATION IN EGYPT [Feb. 1977,

which the best sections are displayed, and partly to the vast
areas which still remain unexplored.

- Nevertheless, there are indications of three well-defined divisions
in the Western Desert, as determined by my own studies, namely :—

(1) Callianassa or Sismondia-logothett Zone, or Upper Libyan.
(2) Ostrea-multicostata Zone. | 'These constitute the ‘ Lower Libyan’ of
(8) Operculina-libyca Zone. Zittel.

Zittel divided his series into two divisions, the Upper and the
Lower Libyan, using the Alveolines for the purpose. The spindle-
shaped Alveolina oblonga (?) Schwag. and A. frumentiformis Schwag.
mark the higher, and the spherical Alveolines the lower division.

The Libyan Series.

With regard to previous work on this subject, it may be noted
that Dr. Blanckenhorn, in his ‘ Neues zur Geologie & Palaontologie
AXigyptens,’ recognized three divisions in the Lower Hocene, namely :
Lower, Middle, and Upper Suessonian, but some difference of
opinion has arisen with regard to the lower member, to which he
has also given the name of the ‘ Kurkurstufe.’ The type-example
of these beds has unfortunately not been studied by anyone pro-
ficient in Egyptian paleontology, since Sir William Willcocks first
drew attention to their existence at Gebel Garra, situated north
of the Kurkur Oasis, near Aswan. ‘The strata occur in the form
of yellow clays 5 metres thick, overlying the Cretaceous paper-
shales and overlain by 90 metres of Lower Eocene limestone. The
fauna is of considerable interest, as described by Mayer-Eymar, in-
cluding Bothriolampas abundans Gauth. and Linthia loriok M.-K.
The presence of the well-known Middle Eocene sea-urchin Poro-
cidaris schmiedela Goldf. has also been recorded from here; but,
having had an opportunity of re-examining the original specimen
(now in the Cairo Geological Museum) with M. Fourtau, I feel
little doubt that it is the spine of a Rhabdowdaris. As Operculina
libyca occurs in the same matrix, the ‘ Kurkurstufe’ of Blancken-
horn in all probability represents the Operculina-libyca Zone, which
seems to be the lowest member of the fossiliferous Kocene over the
greater portion of Southern Egypt.

If the Operculina-libyca Beds and the overlying strata with
Ostrea multicostata appear to be divisions of major significance,
much importance must also be attached to the Upper Libyan
division, owing to its widespread extent and special paleonto-
logical character. Zittel,as already remarked, separated these beds
from those below them by the nature of the Alveolines, and Mayer-
Eymar suggested that the base of the Upper Libyan should be
drawn at his Vummulites-biarritzensis layer, which according to him
seemed to occupy a constant geological position. At the typical
section in the Hill of the Tombs, or Gebel Dranka, west of Assiut,
this bed is above the tombs of the Kings, and at the base of a

Vol!67.] DURING THE CREYACEOUS AND EOCENE PERIODS. 135

series of strata 65 metres thick, rich in Stsmondia logotheti Fraas,
Turritella cegyptiaca M.-E., T. owycrepis M.-E., and Callianassa
nilotica. These strata are of wide extension, for M. Fourtau has
recognized Sismondia logotheti and Callianassa nilotica, associated
with an ovoid Echinolampas (named by him £. humez), in the
collections made by me on the road from Dungul to Nakheil, a
position in the Western Desert about the latitude of Aswan. North-
east of the Baharia Oasis these beds re-appear with the ovoid forms
of Echinolampas, but the typical Callianassa nilotica and Sismondia
logothett have not been recognized.

With regard to the broader geographical relationships during the
Libyan Epoch, much study of detail is required; but, in a recent
paper, M. Fourtau* has pointed out some features of great interest,
in connexion with the distribution of the sea-urchins obtained at
Minia, the Rhabdocidaris navillei Cott. beg a typical Indian
form from Hyderabad, as is also Dictyopleurus haimei Duncan &
Sladen. He adduces reasons for believing that the Egyptian portion
of the Eocene sea formed a centre of acclimatization of the Indo-
Pacific species in their migration to the west, there being no
affinities of this nature either with the Tunisian and Algerian
fauna, or with the Northern Mediterranean basin, whether in
Spain, France, or the Vicentino. He especially calls attention to
the great affinity of this Upper Libyan fauna with that of the
HKocene ‘ Kirthar Series’ in India, citing as examples the close
resemblance of certain species of Conoclypeus from Kirthar to
C. delanouei ; the Sismondia varians is almost a mutation of
S. polymorpha; and among the Cassidulide, which are abundant
in both regions, the genus Gisopygus has numerous representatives
closely related to Indian forms of thisgenus. The genus Kephrenia
appears to be descended from the Indian Paralampas, both being
possibly derived from Pygurostoma of the Upper Cretaceous in
Persia. These Indian affinities are, of course, of much interest and
point out directions of further study ; but the correspondence cannot
be pressed too far, as from my collections in the extreme west
of Egypt, near Baharia Oasis, M. Fourtau has identified the
presence of the genus Pseudop ygaulus, which indicates Algerian
rather than Indian influence.

The Lower Eocene strata, as a whole, appear to be remarkably
uniform in structure and paleontological character over the greater
part of Western Egypt; while in Eastern Egypt the presence
of the ‘remade’ white limestones introduces a problem of a very
complex, if interesting character.

In the next division to be considered, the Middle Eocene, local
variations are presented which suggest the differentiation of
important land-masses in the western and southern portions of
Egypt.

1 « Echinides de Minieh ’ Bull. Inst. Egypt. ser. 5, vol. ii (1908) p. 183.

136 DR. W. F, HUME ON SECULAR OSCILLATION IN EGyFr [ Feb. 1911,

The Middle Eocene.

One of the best-known sections of this formation is displayed in
the Moqgattam Hill above Cairo, and has been carefully studied by
Fraas, Schweinfurth, Mayer-Eymar, Blanckenhorn, Fourtau, and
Barron. The strata displayed in the cliff behind the citadel differ
widely, the lower two-thirds consisting of snow-white limestones,
while the upper red-brown series is characterized by the presence
of numerous beds of detrital materials, mainly sands and clays,
the organic contents of which also indicate their shallow-water
origin. ‘This marked topographical and lithological separation led
Zittel to subdivide the Middle Eocene strata into the Upper and
Lower Moqattam divisions, these being undoubtedly due to im-
portant geological changes.

It is now known, from further study, that to obtain an absolute
definition for these divisions is very difficult, seeing that they have
many points in common, and any means of distinction adopted in
one locality fails when appled to the whole of the Middle Kocene
deposits developed in Egypt. In the Fayum, for instance, the
detailed stratigraphical Jabours of Mr. Beadnell* have made this
region classical ground, and comparison of the results with those
near Cairo show broad differences alike in thickness, fossil contents,
and lithological character.

The Lower Moqattam Series.

This series has a great extension in Northern Egypt, the abund-
ance and variety of its fossil contents with the especial dominance
of large nummulites, Hchinolampas, Schizaster, and the crab Lobo-
carcinus, bearing testimony to the continued prevalence of marine
conditions throughout Northern Egypt. My recent examination
(1909) of the Western Desert between the Nile, the Fayum, and
Baharia Oasis has revealed a very definite system of zones, which
it is well to record for comparison with the Lower Mogattam
succession determined elsewhere.

The observations between the Nile Valley at Beni Suef and the
Moela Oasis have brought into prominence a bed of more than
local interest, which forms both the summit of the series and of an
extremely level plateau in the region round the Moela and Rayan
Oases. The upper portion of this bed near Moela contains a very
globular variety of Lucina pharaonum Bell, accompanied by
crustacean remains; the lower half, on the other hand, consists
almost entirely of minute Porocidaris spines, the bryozoan Eschara
duvali Mich., and other sea-urchin spines which M. Fourtau has
recognized as belonging to Fthabdocidaris gaillardoti Gauth. The
most characteristic feature, however, is the frequent presence of

' See Geol. Surv. Egypt Mem. on the Fayum (1905), with the discussions
of the interesting vertebrate fauna by Dr. C. W. Andrews, and of the inver-
tebrate paleontology of the district by Dr. M. Blanckenhorn.

Vols67.| DURING THE CRETACEOUS AND EOCENE P&HRIODS, 137

large casts of the univalve Gisortia, and of species of the small

sea-urchin Stsmondia.

The Gisortia Bed is of considerable significance, both on account
of its topographical importance and of its wide distribution. In
my own expedition I obtained that large-sized member of the
Conide (Gisortia) on the eastern side of the great gravel desert to
the west of the Moela Oasis; and also on the western side of this
expanse, in the Bahr district close to the northern edge of Baharia
Oasis. Mr. Beadnell records it west of Fashn as a silicified
limestone with large silicified Conide,* and Dr. Ball gives prac-
tically the same description of it, describing it as forming the
plateau-rock near the great belt of sand-dunes.

In Moela it had already aroused the attention of Mayer-HKymar ;
but Dr. Blanckenhorn makes no allusion to any stratum of this
nature in the area studied by him in detail on the eastern bank of
the Nile between Helwan and Minia, nor has it been noted in the
Mogqattam section. It re-appears, however, in the desert between
Cairo and Suez: for, not only is it mentioned in Barron’s Geological
Survey Memoir describing this region (1907), but under the same
name as that adopted by me before I was aware that the term
had been previously used by him.

Near the top of the cliff, at the well-known Gebel Genefe, near
Ismailia, is a bed containing Sismondia semanni Desh. and Gisortia
gigantea Munst., these being overlain by a coral-layer. In the
plateau bordering Gebel Ataqa the upper beds again contained many
Incine, under these being the Dendracis-conferta Bed yielding
Sismondia semanni and other echinid spines. It, in turn, overlies
the Gisortia-gigantea Bed (Barron, op. cit. pp. 93, 95). In Blancken-
horn’s work the nearest resemblance to this stratum is one recorded
as the summit-rock of the Lower Moqattam Series (I. 5): where a
yellow sandy limestone (with Stsmondia cf. logotheti, Thagastea
luciant de Lor., and a number of other species) overlies a hard white
limestone with corals, as in the summit-bed of the Northern Galala
and Gebel Awebed.? This Dictyoconus Bed, as he terms it, appears
to have close relations to the Gisortia stratum.

Enough has been said to show that this white limestone is of
prime importance; and, wherever recognized, this reef-formation
practically marks the close of the Lower Moqattam Series.

The beds which underlie this stratum in the desert south-west of
the Fayum are very variable in character. The first section exa-
mined in the cliff south-west of Beni Suef consisted of :—

(Top.) 1. The snow-white Gisortia Bed, at least 2 metres thick, containing
small nummulites, Eschara duvali Mich., and broken Porocidaris
spines.

2. Vonlow tated cavernous limestone rich in small nummulites and Gryphea
pharaonum Oppenh., with, in places, large bent Carolia.

1 J. Ball & H. J. L. Beadnell, ‘ Baharia Oasis’ Egypt. Geol. Surv. Mem.
1903, p. 22.

2 See M. Blanckenhorn, ‘Neues zur Geologie & Palaontologie Aigyptens’
Zeitschr. Deutsch. Geol. Gesellsch. vol. lii (1900) p. 445.

138 DR. W. F. HUME ON SECULAR OSCILLATION IN EayPr [Feb. 19:3,

In descending the eastern scarp bounding the depression of Wadi
Muela, the succession is seen to be as follows :—

1. Siliceous, cavernous limestone, with the globulose Lucina pharaonwm
Bell, and crustaceans. This is Mayer-Eymar’s I. d, in which he
also records Gisortia, Rostellaria, and Eschara duvali Mich.

2. White chalky limestone, made up of Porocidaris spines, and containing
flints. (Apparently not recognized by previous writers.)

3. Greyish-yellow marls with Gryphea pharaonum Oppeuh.: rich, not only
in that species, but also in Spondylus eqyptiacus R. B. Newton,
Velates schmiedeli Chem., and the large species of Hchinolampas.

4. Marls with Pecten moelehensis M.-H. and Vulsella chamiformis M.-H.

Small nummulites are present throughout the series,

. Clays with gypsum, probably 6 metres thick, and, so far as personal

observation goes, without fossils, overlying

6. The Nummulites-gizehensis Beds, forming the floor of the valley. These
west of Moela contain very large Nautili and Exogyra fraasi M.-H.

Or

Some 40 kilometres to the westward the beds No. 3 were of
especial interest, owing to the great abundance of the smaller sea-
urchins, which include Echinolumpas crameri de Lor., Z'hylechinus
libycus Fourt., Mistechinus mayeri de Lor., etc.* In addition,
Exogyra fraasi M.-E.is very abundant, also the small nummulites,
and afew specimens of Carolia, Solarium, Plicatula polymorpha
(rare). It will be seen that in these Lower Mogattam Beds the
Upper Mogattam fauna is already clearly indicated, so that the
upper line of demarcation is not sharply marked.

As regards the lower line of demarcation, Dr. Blanckenhorn, in his
‘Neues zur Geologie & Paliontologie AXgyptens’ (p. 422), states
that, on the eastern side of the Nile, there is a transition from the
underlying Upper Libyan Beds of the Lower Eocene to the Lower
Mogqattam Series. The former is to a large extent characterized
by the presence of Alveolina; but he found in Wadi Telat
Yusef, 24 kilometres east-south-east of Fashn, Alveolina cf. ob-
longa WOrb., associated with Nummulites gizehensis, N. lamarcki,
and his species V. porosa. In general, however, there is a sharp
distinction between the Middle and the Lower Eocene, the main
points being :—-

(i) The upper beds of the Lower Eocene are characterized by Alveolina,
while the lower beds of the Middle Eocene are characterized by the
large nummulites of which Nummulites gizehensis is the type.

(ii) The Middle Kocene is distinguished by the larger forms of the sea-
urchin Echinolampas (EL. fraasi, etc.), the species of this genus in the
Libyan Beds being smaller and less widely distributed.

(iii) The Conoclypeus delanouei de Lor., on the other hand, characteristic
of the Libyan Beds, is rarely represented in the Middle Eocene.

(iv) The Mogattam Series is especially marked by the large size of the
oysters (Ostrea fraasi, etc.) and the genus Carolia. In the Libyan
Beds oyster-layers are often abundant, but in general these are rela-
tively small (O. multicostata Desh., etc.).

(v) In the Middle Eocene siliceous concretions are comparatively rare, flinty
concretions being only marked in the Gisortia Beds; in the Lower
Eocene silicification has proceeded on a large scale, beds of flinty
concretions forming conspicuous features throughout the series.

1 R. Fourtau, ‘ Description des Echinides fossiles, &c.’ Mém. Inst. Egypt.
vol. vi, fase. ii (December, 1909) p. 171.

Vol. 67.] DURING THE CRETACEOUS AND EOCENE PERIODS. 139

As regards this lower division of the Middle Eocene, the evidence
points to a general similarity of marine conditions at its commence-
ment, the Nummulites-gizehensis Beds being developed within my
own experience at such widely-separated localities as the desert
west of Moela Oasis, Gebel Shaira (60 miles east of Beni Suef),
and the well-known exposures at the Pyramids and in the Moqattam
Hills. Its upper members, however, commence to show those local
variations which make a study of the higher Eocene formations
much more complicated than that of the Lower Eocene or Cre-
taceous conditions.

A striking example of this variation is present in the immediate
neighbourhood of Cairo. When tracing the Upper Mogattam Beds
along the western border of the Nile Valley from the Pyramids to
Wasta, the most persistent member was a stratum rich in Carolia
placunoides Cantr. and Plicatula polymorpha Bell, which served as
a useful guide. Below it follows the remarkable series of un-
fossiliferous impure limestones and marls, in which the famous
tombs at Sakkara have been excavated, and to which I have con-
sequently given the name of the Sakkara Limestones. These only
contain numerous worm-tubes and rare casts of a Lucina. Com-
parison with the highly fossiliferous strata of the Moqattam Hills
(in which sea-urchins are especially abundant) and with the corre-
sponding beds in the Fayum Series bears evidence as to the local
variability in character. Farther south-west, at the extreme
western edge of the Fayum, the changes become still more con-
spicuous, detrital materials almost entirely replacing the fossiliferous
members between the Nummulites-gizehensis Zone and the Upper
Beds containing Carolia placunoides and Ostrea fraasi. The cliff
at this point, probably 100 metres high, is (except for an over-
hanging ledge near the summit containing the above mentioned
Carolia and Ostrea) entirely composed of green clays, spotted sands,
and striped clays.

South-east of the Fayum, in the hill of Der el Gahannem, the
detrital materials play a most important part, a saliferous clay rich
in Ostrea fraasi, Carolia placunoides, and various species of
Turritella, being 20 metres thick. Below it is a series of sands
forming a striking vertical cliff, estimated as 40 metres high. In
the upper part are isolated blocks composed of nummulites, sug-
gesting unconformity between the true Upper Moqattam Beds and
the underlying fossiliferous strata rich in nummulites, from which
they are separated by a thick series of sands, showing remarkable
eurrent-bedding.

This question of unconformity between the strata referred to the
Upper and to the Lower Moqattam respectively was urged by Barron
in his Memoir on the Cairo-Suez region, and the facts so far observed
tend to enhance its significance.

Farther south the Upper Mogattam Beds give rise to a steep scarp
overlooking the broad plain formed by the Nummulites-gizehensis
Series. Here a highly fossiliferous layer forms a hard cap at the
summit of the cliff, the succession being (in descending order) as
follows :—-

140 DR. W. F. HUME ON SECULAR OSCILLATION IN EGypt [Feb. rort,

—

. Bed entirely composed of oysters (O. fraasi M.-E., O. reili
SEGA) aire Oh ah hea Be oes evs Nias Jc Aeceslo? 4 ee eee 4 metres.

2. Carolia-placunoides layer with Turritella casts .............4.
3. Very fossiliferous shelly layer, with Ostrea reili, trochoid

shells, Turritelle, scattered Carolia .........c.cccccccacccecees | metres
4. Beds of shell- fragments, mainly small oysters, with Balanus.
Oe beds oLshupetoysters: «jee ueenaacesk. .50.skad nade about 1 metre.
6. Bed of Ose ret.
em ello w sats) * ys <4 sc. Meese ok os o's cat wie SRR 8 metres.
8. Yellow sands with hire concretions and vertebrze of

Zeuglodon.

In the plain at the base Nwmmulites gizehensis was present.

If the Nummulites-gizehensis Beds be synchronous throughout
Egypt, then these detrital deposits are the equivalents of the
highly fossiliferous limestones of the Moqattam Series and the
unfossiliferous limestones of the Sakkara Series, showing the
enormous local variations occurring during the greater part of
the Lower Moqattam epoch.

The Upper Moqattam Series.

Attention has already been directed to the marked lithological
variation in the beds forming the basal and summit layers of the
Moqattam Hill above Cairo, which led to the separation of the
Middle Eocene into two divisions. It is probable that any attempt
to separate the Upper from the Lower Moqattam Beds throughout
Egypt will not be successful, as the unconformity between them
is not, in any case, of an extensive character. Nevertheless, there
are certain features in which the typical Upper Moqattam Beds
differ in a marked degree from the Lower Moqattam division.

One of the most significant of these is the distribution of the
nummulites, a point which arrests attention when a number of
isolated sections are examined being that, while nummulites of
various species, especially Nummulites beaumonti, and the small
N. schweimfurtht, are extremely common up to a certain level, they
cease very abruptly ; the beds above them, often brownish-yellow,
though containing many fossils present in the nummulitiferous
strata, show no traces of the presence of these foraminifera, In
general there need be no hesitation in referring these non-numm-
ulitic beds to the Upper Mogattam Series. Unfortunately, it is
difficult to draw the base-line of this division, because certain
species which have been commonly regarded as typical Upper
Mogattam forms also occur in the nummulitiferous beds. Among
these we may especially note Hchinolampas crameri de Lor., Anisaster
gibberulus Mich., and Ostrea clot-beyr Bell.

This feature (namely, the absence of nummulites in the Upper
Moqattam), noted in the Mogattam area, in the Fayum, and near
the Pyramids, is widespread in its distribution. In the desert to
the south of the gravel-covered plain, or ‘Serir,’ lying between
Moela and Baharia Oases, and especially in the broken region known
as Kl Bahr, reappear thick strata, characterized by the abundance
of their fossil contents, their brown-red coloration, the rapidity

Vol. 67.] DURING THE CREYLACEOUS AND EOCENE PERIODS. 141

with which they are being denuded, and the absence of nummulites,
which, occurring in thousands at the base of the hills formed by
these beds, are totally absent in the layers forming their lower
slopes. This abrupt change is initiated by a brown bed in which
Turritelle (of the angulata type) occur in immense abundance, above
them being a series of strata in which Ostrea fraast and Carolia
attain an exceptional size.

After careful comparison of these exposures with those already
known to me in the Nile Valley, I conclude that the salient characters
of the Upper Moqattam Beds, viewed as a whole, are :-—

(a) The exceptional abundance of beds of Carolia placunoides and Ostrea

fraasi.

(b) The association of Plicatula polymorpha Bell in large numbers with
the Carolia. This association is a constant feature from near the
Pyramids to Baharia, and therefore this occurrence is of more than
local significance. In the Lower Mogattam this Plicatula is present,
but within my experience only as isolated individuals. Dr. Ball

informs me that he found a similar association near the Red Sea, due
east of Cairo.

(c) The general absence of nummulites.

(d) At times an exceptional development of species of Turritella, espe-
cially at the base of the series.

(e) The dominance of Echinolampas crameri and Anisaster gibberulus
when conditions are fayourable to the presence of sea-urchins.

Further study will probably indicate a triple division of the
Middle Eocene as being the most convenient ; the Middle Mogattam
Beds in such a case would be characterized by the abundance of
the Exogyra-fraasi bands, and a great development of the smaller
nummulites (Vummulites schweinfurth, N. beaumonti, etc.). The
following synopsis shows the boundaries of these divisions, as com-
pared with previous classifications :—

| | Schwein- Mayer- Blancken- Fayum Hume (north of

| Surth. Eymar. horn. (Beadnell). _ Baharia Oasis).

| ee AAA b toe. TE, Qasr-el-Sagha Non - Nummulitic

Aig asein and 4 to 8. Beds. Carolia Beds.

| et (Carolia Beds.)

oe AAA a £E Birket - el - Small Nummulites
5 and 1 to 3. Qurun Beds. and Exogyra Beds.

| Moa@artaM.| 44 4 7. F

| Ache? Ee £ Wadi Rayan Gisortia Limestone.

| Lower ete, etc. and Ravine Gryphea - phara -
MoagatTramM. Beds. onum Beds,

|
Nummulites - gizch - |
| ensis Beds. |

142 DR. W. F. HUME ON SECULAR OSCILLATION IN EGYPT [ Feb. 1g11,

I have purposely refrained from comparing these strata more
closely with the Kocene formations of Europe, as this would require
a more careful paleontological analysis than time has permitted me
to undertake. Only such a study will finally decide whether the
Upper Mogattam as above defined should be regarded as Upper
Eocene, instead of being considered, as it was originally, the
uppermost member of the Middle Kocene.

The Caleareous Grits.

The final stages in the history of this passage from the widespread
Eocene sea to the Oligocene continental conditions are witnessed by
the calcareous grits, which underlie the pebble-gravels forming the
surface of much of the Western Desert of Egypt between the Fayum
and Baharia Oasis. In these the individual rounded sand-grains
are cemeuted in a calcareous paste. A typical section of this
Calcareous Grit series was studied in the Gebel Hadahid scarp,
where it is crossed by the main road from the Fayum to Baharia.
The succession is as follows, the beds dipping 5° northwards :—

Thickness in metres.

1. Quartz-chert pebble-gravels (forming the summit)... 50
2. Saidy limestone (composed of fossil fragments) ...... 2°5
3. i mable consoludaredssanGs <....c... .:..a0deeerseesp earner 15:5
4, Very false-bedded sands (calcareous)......... oS. 30
6.7 Vellowse le vasaiG ae reer sess. cece e0caeceen eee eeeeeee 16
6. Sandy shales (very friable) with solid yellow sandy
CON CHEN ONS eae ee Bee oreo eis vbcu +! +: acceler eee 08
We Ne lowaclaiy eygsam ls een. e etl ore c's, scat oe eee eee 40
Mota va scsc tree ance meee 32°4

Below these in the valley is a Lucina-cast bed, overlying a sandy
layer with scattered Turritella and Cardita. ‘This unfossiliferous
serics is not of purelv local occurrence. for it reappears from under
the pebhle-gravels to the north of Baharia, forming conspicuous

cliffs and the very marked hill to which the name of Had el Bahr

was given, which is composed of complex sandy grits. The same
beds were again observed at only 3 kilometres from the north-
western edge of the Baharia scarp.

Though not actually traced step by step into the series so clearly
described by Mr. Beadnell in the ‘ lopography & Geology of the
Fayum Province’ (Mem. Egypt. Geol. Surv. 1905), these strata must
represent his Fluvio-Marine division, and (judging from p. 63
of that memoir) probably that portion which has been classed with
tle Upper Eocene. A similar calcareous grit frequently rises
through the gravel-beds, and may be regarded as Oligocene ; these
strata, therefore, appear to be of considerable importance, not
only as regards their paleontological interest 1m connexion with
the occurrence of Arsinoitherium, etc., but also on account of their
wide distribution in the Libyan Desert.

The succession in the El Bahr region north of Baharia Oasis

Vol, 67.] DURING THE CRETACEOUS AND EOCENE PERIODS. 143

is practically an epitome of the most typical sequence of the
Eocene and Oligocene strata observed in North-Western Egypt, a
dip of 5° at this locality bringing up the whole of the Middle Eocene
strata within a limited area as follows :—

Thickness in metres,
. Sandy limestone with chert cap. .............-. \ 29 { Probably
. Sandy limestones — .............-:eeseeeseeeees eee % Oligocene.
. Beds containing Ostrea fraasi, Carolia placu-
noides, and Plicatula polymorpha, without 15 | ape
Huta miulites . eee es oe ee enti t ose Mogattam.

CO hoe

4. Brown Turritela Beds ...... BE Pees oea sane:

5. speaae small hee and el { Middle

G.- Ostrea, clot-Beat Beds fl sata sk .ois's ese Eee itodatea
GpSOTrtGs EAMHESHOMO ter tie oe Serna a5 2 nie oc Dawe

8. Yellow limestone (Gryphea-pharaonum Zoue). |

9. Nummutites-gizehensis Series ..........2-+-+-000+ EGE
10; Gisopygus Beds «tigre. sce cess nae eee ees 2 oh Upper Libyan.

The term Moqattam Beds, introduced by Zittel, has become
so well established in the literature that it does not seem advisable
to add a new name to the terminology ; but a triple division of this
formation seems necessary, in order to bring out the very important
change marked by the disappearance of the nummulites. This
triple division can be traced in all the important areas hitherto
studied (see Table, p. 141).

IX. GeneRAL SUMMARY.

The main points to which reference has been made in this paper
may be summarized as follows : —

A.—1l. There was a gradual advance of the Cretaceous sea
over Egypt during Cenomanian to Danian times, from north or
north-east, five stages in this advance being indicated by the rela-
tions of the detrital Nubian Sandstone to the organic Cretaceous
limestones. ‘These phases are :—

(a) The Northern Egyptian type, extending from Sinai to
Baharia Oasis, in which the Nubian Sandstone underlies.
fossiliferous marls of Cenomanian age, while limestones
were forming during the remainder of the Upper Cretaceous Period
(Turonian, Senonian, and Danian). The Cenomanian beds contain
characteristic sea-urchins (Hemiaster of the cubicus type, etc.) and
oysters (Ostrea olisiponensis, O. suborbiculata, O. flabellata, etc.).
A minor facies is the Baharian (Baharia Oasis), in which a
Cidaris-thomasi Bed is exceptionally developed at the close of the
Cenomanian. At Abu Roash, on the other hand, the Turonian
strata attain a thickness not elsewhere observed in Egypt.

(b) The Wadi Qena type was recognized during my recent
expedition (1910) in the upper reaches of Wadis Wena, Tarfa, and
Hawashia. The characteristic feature is the alternation of
Nubian Sandstones with fossiliferous Cretaceous strata.
At least three typical sandstone-bands are present: (1) an Upper

144 DR. W. F. HUME ON SECULAR OSCILLATION IN EGYPT [ Feb. 1911,

Nubian at the base of the Campanian; (2) a Middle Nubian above
the Turonian ammonite-bed ; and (3) a Lower Nubian below the
Cenomanian strata and closely related to them.

(c) A Central Egyptian or Hammama type, extending in
the Eastern Desert and on the Nile between latitudes 25° N. and
26° N. In this phase the Cenomanian and Turonian strata are
absent, the Nubian Sandstone forming the greater por-
tion of the Cretaceous System, with Santonian oysters
(O. boucheront, O. bourguignate) in its highest beds. The overlying
Campanian Series is characterized by the abundance of Ostrea villez,
Trigonoarca multidentata, and by phosphatic beds with Otodus
auriculatus. The Danian member has an eastern facies, in which
Pecten Marls are the principal feature, and a western (the Oasis
type), where a fauna of small gasteropoda, species of Hchinocorys,
erinoids, and Terebratulina ef. gracilis, occurring in a chalky lime-
stone, indicate a close affinity to the White Chalk of Northern
Kurope.

(d) ASouth Egyptian Cretaceous type has close resem-
blances to the Central Egyptian; but in the Campanian
the phosphatic beds are inconspicuous, and the fauna
consists of a group of small sea-urchins (mostly new species) and
of gasteropoda, among which large Turritelle are prominent. This
facies is developed at Dungul Oasis and in the Cretaceous ex-
posures on the Arbain road, south of Kharga Oasis.

2. The Danian fauna of the oases (small gasteropoda and corals)
has been found east of the Nile near Esna in close relation to the
Pecten Marls, the Oases and Hammama types being thus linked
together.

3. As a result of the Wadi Qena expedition of this year (1910),
the foregoing facts bear the strongest testimony to the Cretaceous
age of the Nubian Sandstone.

B.—Regarding the transition from the Eocene to the Cretaceous,
we note :—

4, The existence of two different types of strata at the base of
the Eocene, the first, or Luxor type, being characterized by the
abundance of Operculina lbyca, large sea-urchins (Lthabdocidaris,
ete.), and bivalves (Lucina thebaica), almost immediately overlying
shales with the small Cretaceous (Danian) fauna; the second, or
Qena type, being, on the other hand, entirely unfossiliferous and
composed of white limestones having the closest lithological resem-
blance to the typical Danian white chalk with Pecten farafrensis
or P. mayer-eymara, etc.

5. Though lithologically resembling the Danian limestones, those
of the Qena type, which underlie strata of proved Eocene age (con-
taining Nummulites variolarius and N. curvispira), are remarkably
jointed or honeycombed, and very susceptible to denudation, as shown
by the numerous caves, natural bridges, and cylindrical pipes formed
in them.

As an explanation of these differences, it is suggested that these

Vol. 67.] DURING THE CRETACEOUS AND EOCENE PERIODS. 145

Lower Eocene deposits represent the first evidence of the reversion
in the secular oscillation, the land gaining on the sea, and being
accompanied by folding. ‘The new Kocene fauna flourished on the
worn surfaces of the shallow arches, while the denuded Cretaceous
material was deposited in the deeper basins.

6. As the Cretaceous beds in the North of Egypt were deeper
beneath the sea at the close of the Cretaceous Period, they only
became exposed late in Eocene times, thus accounting for the strong
unconformities between the Cretaceous and the Eocene (mainly
Middle Eocene) strata noted in Northern Egypt.

7. The above explanation would account for (a) the slight change
in lithology, accompanied by the marked difference in fossil contents ;
(6) the striking resemblance in petrographical character, but dif-
ference of physical structure, in the biscuit-coloured limestones of
Eastern Egypt; and (c) the presence of strong unconformities
between the two formations in Northern Egypt. The origin of the
erystalline limestones is still too much wrapped in obscurity for a
definite opinion on this subject to be given.

8. Paleeontologically, there are the usual well-marked differences
between the faunas of the uppermost Cretaceous and the lowest
Eocene deposits—great groups, especially the Ammonites, entirely
disappearing at the close of the Cretaceous; while the Nummulites
and Operculina appear in vast numbers in the earliest strata of
Eocene age.

9. Though this great change be of prime importance, yet both
periods bear a strong mutual resemblance in the dominance of
oysters and sea-urchins over the other classes of animals.

10. A notable feature is the extreme rarity of the Brachiopoda
in Egypt throughout Eocene and Cretaceous time; as a point of
interest, apart from the general question under consideration, it may
also be noted that no Belemmites. so far as | am aware, have ever
been recorded from the Egyptian Cretaceous.

C.—With regard to the distribution and variation of the Eocene
beds, we may note :—

11. The apparent uniformity of the fossiliferous Lower Eocene
beds wherever developed in Southern Egypt; the triple zonation
into Upper Libyan, or Calliunassa-nilotica Zone, and Lower Libyan,
including the Ostrea-multicostata and Operculina-libyca Zones;
Conoclypeus delanouet, Lucina thebaica, and various species of
Alveolina are, in addition, among the more characteristic forms.

12. In the Middle Kocene this uniformity is replaced by dif-
ferentiation, only the lowest, or Nummulites-gizehensis Zone, being
traceable throughout the whole area where these beds are exposed.
Comparison of the sections in the well-known regions of the Fayum
and the Moqattam Hull with the Western Desert area specially
described in this paper reveal how great are the variations, both
lithological and paleontological.

In the desert between Banaria, Moela, and the Fa ayum Oases,
three major zones have been recognized in the Lower Mogattam

Q.J.G.8. No. 265. L

146 DR. W. F. HUME ON SECULAR OSCILLATION IN EGYPT [Feb. rg11,

Series of the Middle Eocene: namely, from the base, (a) Nummulites-
gizehensis Zone, (3) Gryphea-pharaonum Zone, and (y) Gisortia
Limestone, the last-named being also of far wider extent and
importance than had hitherto been suspected.

13. In the Upper Mogattam division of the Middle Eocene the
Turritella Beds near the base, and the strata containing Carolia
placunoides and Plicatula polymorpha, are of wide range; beds of
detrital materials become of much importance; and nummulites
cease to form part of the fauna.

14. The increasing importance of the detrital materials is shown
by the Calcareous Grits, which have a wide extension in the
North-Western Desert of Egypt, but differ in character from the
mammaliferous beds of the Fayum, which are conspicuous by their
brilliant colouring and by their sandy character. Their precise
age-relations are uncertain, as they have hitherto not yielded fossil
remains of decisive age.

15. The quartz-chert gravels forming the surface of the highest
desert between Baharia and the Fayum are unconformable to the
Calcareous Grits, though closely related to them as regards dis-
tribution, the suggestion that they are of Oligocene age being based
on Dr. Blanckenhorn’s analysis of certain freshwater shells obtained
m them by Mr. Beadnell. The rounded character of the quartz-
and-chert gravel and the presence of fossil wood bear witness, in
conjunction with the occurrence of great land-mammals, to the in-
coming of continental conditions at the close of the Kocene Period.

16. This continental phase is accompanied by many indications
of volcanic activity, for to this period belong the dolerites of Baharia,
various basaltic occurrences in the Western Desert, the Fayum, and
at the well-known quarries of Abu Zabel, near Cairo. Interesting
examples of a similar nature have been recorded from the Eastern
Desert, one of the latest of these being some remarkable intrusions
through the Danian and Eocene rocks which I observed at the head
of Wadi Um Hemaiet, near Wadi Qena.

The Cretaceous Period in Egypt is, therefore, one in the main
marked by the gain of sea over land; during the Eocene, on the
contrary, the land appears to have been steadily gaining on the
sea, probably concurrently with gentle fold-movements, which
account for the minor differences in the nature of the Eocene
deposits. At the close of Kocene times, and during the Oligocene
Period, the approach of a continental phase is clearly indicated.

EXPLANATION OF PLATE VI.
Sketch-map, on the scale of 1: 6,000,000, showing the extension of the
Kocene and Oligocene strata in Egypt.
Discussion.

Mr. A. Wane said that, so far as his personal knowledge of the
geology of Egypt was concerned, he was in agreement with the
conclusions drawn by the Author. The correlation of the almost

SKETCH-MAP SHOWING
THE EXTENSION OF THE EOCENE
AND OLIGOCENE STRATA
IN EGYPT.
Scale: 1:6,000,000.

IsmailicdX

CAIRO
5 iocene

Helwun
WS

ae

aE occa a al

ee Sig em”,

.
Peet Pa setece

“

D . v- .y:
7» Metamorphic, Area 17287

aL
tee
uw aa he

: nye Gh Sy - pV MNT ca
Pe I Se . nD PRL Oak ie tp ua

Scie 7 ao © - pk -3- - at Ye yt "ie ~ Ap. ka
4 Sandstone--:- Pe OD ct PGP atg Me Me ted ot take

<

Cuart. Journ. Geol, Soc. Vol. LXVII, Pl, VI.

SSS SS Nuchtie | SSS —————————
: \lexandrisy = oe ==
7)

Ismaili SKETCH-MAP SHOWING
Ree QQ THE EXTENSION OF THE EOCENE
K \Miocene

AND OLIGOCENE STRATA
Mbyattam —SueZ,

- 1 Sak Sa
Quartz and Chert; ae Helwan Se = IN EGYPT,
7.25 Gravels Ss Scale: 1:6,000,000.

Unexplored NEN
. : Fayum
A G OG MiEla,
Siwa Oasis % a Lower oasis
P U; VS
——— Pper Mo
, SS = Gattam ‘
Extension DOWer SSS NERS
; Si Mogattamee SA
uncertain m : .
under

Sand dunes

uncertain

Sandstone

Explanation

Oligocene Quartz and Chert Gravel ree

tae Danian & Campania
MUM cenomanian Beds ; SENG a. arnt 1
Lower Moqattam Nubian Sandstone Sy oss Gr ie
noone Libyan ea Graniticand Metamorphie Ayeas

* = Alternation of Nubian Sandstone & Cretaceous Limestones. Nubian

Cretaceous
Middle Upper Moqattam
Eocene

PF

a

Vol. 67.] DURING THE CRETACEOUS AND EOCENE PERIODS. 147

unfossiliferous biscuit-coloured limestone of the Eastern Desert
with fossiliferous beds of Eocene age in the Western region was
interesting. He had found fragments of sea-urchins which seemed
to confirm the Author’s theory as to the detrital origin of the
Eastern facies. He referred the Author to an early statement
made by him that the gypsum deposits of the Red Sea area were
altered Cretaceous, and asked him how he accounted for the fact
that, in places noted by the speaker in the Eastern Desert region,
the ‘ biscuit-coloured limestones’ apparently crop out from under
the gypsum series,

Dr. FaucoyeEr said that he was interested to find in the paper the
suggestion of a possible unconformity between the Cretaceous and
the Eocene. In Northern Nigeria, where he had had an oppor-
tunity of working, there was a decided unconformity between the
Cretaceous and the Eocene, and he was inclined to believe that the
break at the close of the Cretaceous Period would ultimately be
found to have been more or less general throughout the Sudan.

With regard to the photographs illustrating eolian erosion, he
asked the Author whether or not he believed with Walther that
the formation of the cliffs and escarpments, as well as the sculpture
of their surface, should be assigned to the action of the wind.
Similar features in Nigeria were more readily explicable on the
assumption of fluviatile erosion.

Dr. A. P. Youne welcomed the discovery of evidence clearly
indicating the relations of the Nubian Sandstone to definite stages
of the Lower and Middle Cretaceous. The range of the Nubian
Sandstone in depth seemed still to require elucidation. On account
of the easy solubility of the carbonate in both fresh and salt
water, the speaker was inclined to question the probability of an
important series of limestones being formed by mechanical trans-
portation of material derived from an older source.

Dr. J. W. Evans enquired whether the Author had made any
comparison between the Cretaceous and Eocene of Egypt and the
strata of presumably similar age in Cyprus.

Dr. A. 8. Woopwarp referred to the fossil eel and fossil sole
exhibited by the Author from the Hocene of Tura, and remarked on
the extremely close resemblance between these fishes and their
existing representatives.

Mr. A. E. Kirson was interested to find that the Author had proved
in Southern Egypt a gradual transition from the Cretaceous to the
Eocene. He himself had found in Southern Nigeria, between the
Niger and the Cross Rivers, that fossiliferous Cretaceous beds, having
a slight west-north-westerly dip, appeared to show a gradual transi-
tion from marine, through estuarine and lacustrine, into possibly
fluvio-lacustrine deposits. ‘These were unconformably overlain by
Tertiary sands. Nearer to the Niger, and west of that river, fresh-
water deposits with beds of brown coal occurred; while in other
districts there were marine limestones, sandstones, shales, and clays.
Both groups were fossiliferous, normally almost horizontal, and
were probably of Eocene age. Field-evidence suggested no marked

L2

148 CRETACEOUS AND EOCENE OF EGYPT. [Feb. 1911,

unconformity, even if any, between the freshwater Cretaceous and
the freshwater Tertiary.

Dr, Falconer had spoken of an unconformity between Eocene and
Cretaceous rocks in Northern Nigeria. But would that necessarily
imply an unconformity between EHocene and Cretaceous in French
territory to the west of Northern Nigeria, or in Southern Nigeria ?
Might there not have been, in some parts of the great Cretaceo-
Kocene basin or group of smaller basins that formerly existed in
Northern Africa, a transition from marine Cretaceous to marine
Kocene, as in Southern Egypt, or from lacustro-estuarine Cretaceous
to a similar group in the Kocene? Differential movement of the
land-surface could cause in local areas alternations between sedi-
mentation and erosion, with considerable or intense folding and
faulting in one area and little or none in another.

The AurHoR, in reply, said that the precipices in Egypt were due
in many cases to direct erosion by water, acting during very short
periods with exceptional violence. In other instances, where
great thicknesses of Eocene limestone rested upon soft shales, the
latter yielded under the pressure, causing masses of limestone to be
broken off, and thus leaving new precipice faces.

Erosion by fresh and salt water was naturally very important,
the point being that the ‘remade’ biscuit-coloured limestones showed
the effects of such erosion in a much higher degree than was the
case with the true Danian limestones underlying them.

The opinion as to the Cretaceous and Eocene age of the gypsum
at Jemsa should be still considered sub judice, no definite evidence
being available. Undoubtedly there were large deposits of gypsum
of very varied ages in Egypt, from the Pliocene downwards; and
each of these had to be considered on its own merits.

The Author further said that he had not visited Cyprus, and the
question of the origin of the crystalline limestones there, as weil as
of those in Egypt, was one of the most difficult under consideration
at the present time.

In reply to a question put by Mr. Whitaker, the Author remarked
-that there were undoubted differences in the Nubian Sandstone,
green shales being more abundant in its upper portion. ‘The strata
alternating with the fossiliferous Cretaceous beds near Wadi Qena
would, if found elsewhere, be unhesitatingly regarded as true
Nubian Sandstone.

The Author thanked Dr. Smith Woodward for his remarks on the
Egyptian Eocene fishes exhibited, and pointed out that they were
kindly presented to the Cairo Geological Museum by Mr. Crawley,
head of the Technical Department in Cairo, who also supplied notes
as to their supposed source of origin.

With regard to the general question of conformity and uncon-
formity, the results obtained required caution in deduction, the
Eocene and Cretaceous in the south showing more evidence
of conformity than was the case in the north. Nevertheless,
throughout Egypt the paleontological break was great, so far as the
Author’s experience went.

Vol. 67.] INSECT-REMAINS FROM THE SOUTH WALES COALFIELD. 149

4. On a Coxtection of Insncr-Remais from the Sourm WaAt.EzEs
Coatrierp. By Herserr Borron, F.R.S.E., F.G.S., Curator of
the Bristol Natural History Museum. (Read January 11th,

£911.)
[Puates VII-X.]
ConTENTS.
Page
Es Vite ete ae oe aaa Sc mds oe Lakcwaa eer 149
TE, “Geokomival Rimi oes nso s o. souskapensstaesanences 151
Tit. Description of the Specimens ........../.......0..62- 152
EV; General Qbeampmi tong fs. oie nc eas ec hatkalss ceo onsen 172

1. Lyrropucrion.

I am indebted to the courtesy of the Director of H.M. Geological
Survey, for the opportunity of examining and describing an
interesting suite of blattoid remains obtained by the officers of
that Survey from the South Wales Coalfield.

_Insect-remains of Carboniferous age are so rare in this country
that the finding of no less than nine specimens, three of them with
their counterparts, constitutes an event of considerable paleonto-
logical interest. The South Wales Coalfield has thus yielded more
examples and more species than all other British coalfields together.
All the specimens, with one exception, are blattoid in character.

The total number of fossil cockroaches known from the Carboni-
ferous is now great, and nearly all the numerous genera and species
are founded upon the anterior wings or tegmina alone. Only
once in this country, so far as [ am aware, have larval stages been
recognized.’

The number of specimens and of species recorded from the
British Coal Measures is singularly small, the great bulk of known
forms occurring in Continental and North American coalfields.
Dr. Henry Woodward,’ in quoting S. H. Scudder’s’ census of
blattoid forms, mentions 14 genera and 69 species as recorded
from all Carboniferous sources.

He also mentions that Miall & Denny* quote Scudder as recording
the number of Paleoblattariz at 70 species. Scudder was followed
by Dr. E. H. Sellards,’ who took a broad survey of the whole

1 H. Woodward, ‘On the Discovery of the Larval Stage of a Cockroach, }
Ettoblattina peachii’ Geol. Mag. dee. iii, vol. iv (1887) p. 433.

* “Some New British Carboniferous Cockroaches’ Jbid. p. 49.

% «Paleozoic Cockroaches: a Complete Revision of the Species of both
Worlds, with an Essay towards their Classification’ Mem. Boston Soc. Nat.
Hist. vol. iii, pt. 1 (1879) pp. 23-134 & pls. ii—vi.

4 ‘Structure & Life-History of the Cockroach, Periplaneta orientalis’
London, 1886, 8vo.

° «Study of the Structure of Paleeozoic Cockroaches, with Descriptions of
New Forms from the Coal Measures’ Amer. Journ. Sci. ser. 4, vol. xviii (1904)
pp. 113-34, 213-27 & pl.

150 MR. H. BOLTON ON INSECT-REMAINS [ Feb. 19me,

subject, describing the structure of Paleozoic cockroaches with
remarkable detail, and adding eight new species and one genus.
Dr. Sellards was fortunate in securing several remarkably good
forms, which he figured and described.

Still more recently, Dr. Anton Handlirsch* has subjected the
whole of the American forms to a critical examination and revision,
and has modified to a considerable extent the work of.Scudder
and Sellards, more especially that of the former. According to
Dr. Handlirsch, the Paleeozoic cockroaches, all of which he groups
under the order Blattoidea, number close upon 74 genera and
271 species. About 70 of these species cannot as yet be referred
with certainty to any known genus. The genera are divided into
nine families.

The British forms at present known are comparatively few, and
are as follows, arranged in order of their date of publication :—

Erosiatrina (Buarripium) MantipioipEs (Goldenberg) (‘ Fauna
Sarzepontana Fossilis’ 1877, p. 20).
J. W. Kirkby, ‘ Remains of Insects from the Coal Measures of Durham’
Geol. Mag. vol. iv (1867) pp. 388-90 & pl. xvil, figs. 6-7. (‘ Portions of the fore-
wing or tegmina [sic] of an Orthopterous insect nearly allied to Blatta, from
the Coal Measures opposite Claxheugh, near Sunderland,’ referred to Blattidiwm
mantidioides.) S. H. Scudder, Mem. Bost. Soc. Nat. Hist. vol. 111, pt. 1 (1879)
pp. 72-73, woodcut, subsequently transferred the species from Goldenberg’s
genus Blattidiuwm to Htoblattina.

ETOBLATTINA JoHNSoNI H. Woodw. 1887.
LITHOMYLACRIS KIRKBYI H. Woodw. 1887.

LeEProBLATTINA Ex1ILIs H. Woodw. 1887.

Dr. Henry Woodward? described the foregoing new species in
1887 from four examples, three of which had been obtained from
the clay-ironstone band between the ‘ Brooch’ and the ‘Thick Coal ’
at Coseley near Dudley: they were all preserved in nodules of
ironstone. The fourth specimen had been obtained by the late
James W. Kirkby from the Upper Coal Measures, near Methil on
the Fifeshire coast. This specimen is the Lithomylacris kurkbyi of
the above list.

EtrospLaTtina PEACHII H. Woodw. 1887.

In the ‘Geological Magazine’ for the same year (p.433), Dr. Wood-
ward described the occurrence of the larval stage of a new species,
which had been found in a lght brown nodule of clay-ironstone
obtained at Kilmaurs (Ayrshire).

1 « Revision of American Paleozoic Insects’ [Transl]. L. P. Bush] Proc. U.S.
Nat. Mus. vol. xxix (1906) pp. 661-820.

2 «Some New British Carboniferous Cockroaches’ Geol. Mag. dee. 111, vol. iv
(1887) pp. 49 e¢ segg.

Vol. 67.] FROM THE SOUTH WALES COALFIELD. 151

Fovaura CAMBRENSIS Allen, 1901.

Two previous occurrences of insect-wings are recorded from the
South Wales Coalfield. Mr. H. A. Allen ' described and figured a
wing found in shale overlying the 4-foot seam in the Lower Coal
Measures of Llanbradach Colliery (Cardiff), to which he gave the
name of Youguea cambrensis. The genus Fouquea, to which Mr.
Allen referred his specimen, was created by Charles Brongniart,*
who pointed out its close agreement with Jithomantis in the
neuration, while it greatly differs in its reticulation, the nervules
being so numerous as to anastomose and form a complex network.

ARCHIMYLACRIS (ErToBLATTINA) WOoDWARDI Bolton (1910).

In the early part of 1910 I described * a new species of cockroach,
Archimylacris (Htoblattina) woodwardi, from a tegmen found by
Mr. David Davies, F.G.S., in dark blue shale overlying the No. 2
Rhondda coal-seam at Clydach Vale. Both these horizons are
represented in the vollection obtained by the Geological Survey.

II. Grotogican Horizons.

The specimens now to be described are nine in number, and have
been obtained from the Mynyddislwyn Vein, the Swansea 4-foot
- seam, the Graigola Seam, and the well-known Rhondda No. 2 Seam.
The Mynyddislwyn Vein is a noted house-coal, and is taken by the
Geological Survey as the base of the Upper Series of Coal Measures.*
It is generally correlated with the Llantwit No. 3, the 4-foot or
Maesmawr Seam, and the Bedwas Vein.

The officers of the Geological Survey regard the Wernffraith or
4-foot Seam of Swansea as the equivalent of the Mynyddislwyn Vein
of Monmouthshire; but by some authorities the Graigola seam is
believed to correspond to that vein.? In accordance with the
former view, the Swansea 4-foot Seam (under a variety of names,
such as Llanelly 6-foot, Box Big Vein, Primrose Seam, and Broad
Oak Vein) forms the base of the Upper Series in the Swansea
district, just as the Mynyddislwyn Vein does in the Monmouth
area.”

The Graigola or 6-foot Vein lies 250 yards below the Swansea
4-foot Seam, and is therefore, according to the Survey classification,
in the Pennant Series. The Rhondda No. 2 Seam occurs at the
base of the Pennant Series.

If we take the Geological Surveyors’ view of the correlation

1 Geol. Mag dec. iv, vol. viii (1901) pp. 65-68.

* *Recherches pour servir 4 |’Histoire des Insectes fossiles des Temps
primaires’ St. Etienne, 1893, p. 372.

3 Geol. Mag. dec. v, vol. vii, pp. 147-51 & pl. xv.

4 * Geology of the Country around Newport ’ Mem. Geol. Surv. 1909, p. 76.

° *Geology of the Country around Swansea’ Mem. Geol. Surv. 1907,
pp. 34, 35.

6 Ibid. pp. 33, 35, 104.

152 MR. H. BOLTON ON INSECI-REMAINS [Feb. 1911,

of the Mynyddislwyn and Swansea 4-foot Seams as correct, it
follows that of the nine specimens obtained, six came from the
Mynyddislwyn horizon at the base of the Upper Series. Two speci-
mens have been obtained from shales associated with the Graigola
Seam, and a 22-inch seam 40 yards below it; while one specimen
comes from shales near the Rhondda No. 2 Seam, and therefore on
the same horizon as the example of Etoblattina (Archimylacris)
woodwardt Bolton, already described by me.’

It thus appears that the whole of the insect-remains are refer-
able to three horizons, one at the base of the Upper Series, and
two in the upper part of the Pennant Series. The specimens, the
register-numbers of which in the books of the Geological Survey
are 24501, 24502, 24503, 24504, 24505, 24506, 24507, 24508, all
come from the Mynyddislwyn Vein; 245V1—24503 having been
obtained from the Gellideg level, and 24504-24508 from the
Gwernau level, both in Monmouthshire, near Maes-y-ewmmer. No.
24510 is from the 4-foot Seam of Swansea, and therefore, as supposed,
on the Mynyddislwyn Vein horizon. Nos. 24511 and 24512 are
from shales associated with the Graigola Seam, and a 22-inch seam
_ 40 yards below it ; while 24509 is from the No. 2 Rhondda Seam.

III. Descriprion oF THE SPECIMENS.

ARCHIMYLACRIS sp. indet. (PI. VII, fig. 2.) [Reg. No. 24508.]

Impression of the basal portion of the left tegmen. A good
portion of the base is hidden; the anal area is either concealed
under a large pronotal shield or is absent; and two-thirds of the
distal part of the wing are also gone. This is all the more to be
regretted, because of the presence of a detached pronotum, which
will be described later.

The sub-costal area is strap-shaped, the vein running parallel to
a very slightly curved outer wing-margin. The vein is thin, much
less robust than the adjacent radius, and gives off a single branch
low down, which passes obliquely forward, forking just before
reaching the margin. ‘The main stem of the sub-costa also forks
at the same level, and sends two large branches to the distal end of
the sub-costal area. Only the main stem and its terminal forks
can be seen in the photograph. The radial vein, while stronger
than the sub-costal, is less so than the median vein, and its branches
are correspondingly feeble. Three branches, all directed outwards,
can be distinguished, and all follow the same oblique direction as
those of the sub-costa. Whether the radius reached the tip of the
wing, it is of course impossible to say, but the obliquity of the veins
renders this very likely.

The media is small, and branches high up, near the middle of
the wing. Only faint traces of two branches are discernible near

1 Geol. Mag. dec. v, vol. vii (1910) p. 147.

Vol. 67.] FROM THE SOUTH WALES COALFIELD. 153

the broken edge. The course of these vein-fragments indicates that
the marginal area of the median was confined to the apex of the wing.

The cubitus is a strong vein. Four backwardly directed branches
are distinguishable, beyond which the main stem continues outwards
in an almost straight line. The branches have the same obliquity
to the margin, but in a direction opposite to those of the scapula.
A raised line some distance out from the base, at its lower end
touching the pronotum, may represent a basal branch of the
cubitus or may lie in the anal area. It is doubtful whether it
ean belong to the anal area, as its course is perfectly straight and
fairly parallel to the branches of the cubitus. I am inclined to
regard it as a basal branch of the cubitus, and to think that its
present position is due to fracture of the wing, and subsequent
displacement.

It is impossible to form any idea of the length or breadth of
the wing, so little is preserved, the total length of the fragment
being only 10 millimetres. This fragment has been broken along
the line of the median vein, and a portion of the wing is missing.
I have already alluded to a possible displaced portion of the cubitus.
The wing-surface was destitute of wrinkles, and the interspaces
between the veins slightly convex (concave in the cast).

Affinities.—The general characters of the branching of the
veins, and the strap-shaped sub-costal area are, I think, sufficient
to justify the classification of the specimen with Archimyilacris.
Specific determination of so small a fragment is impossible.

Horizon.—Mynyddislwyn Vein, Gellideg Level, near Maes-y-
ewmmer (Monmouthshire).

Associated with the impression of the fragmentary wing No. 24508
is a pronotum wholly unlike that of any blattoid known to me. It
is in actual contact with the base of the impression, and lies with
the dorsal side uppermost. It consists of a raised axial division,
convex from side to side, and narrowest anteriorly. It appears
to swell out backwards, assuming a somewhat pyriform shape.
The sides are plate-like expansions, semilunar in outline, and with
a very slightly convex dorsal surface, the convexity being greatest
over the inner concave portion of the plate, and dying out on the
free margin. The front portion of the axial division has been
broken away, and there is nothing to indicate whether a rostral
prolongation was present or not. The hinder central portion is
also missing, and rising up out of the stony matrix filling the gap
are the edges of two coriaceous body-segments. The central axial
portion of the plate is black, while the lateral expansions have the
colour of the matrix. Both sides preserve traces of the superficial
texture, the left side being far the best in that respect. The
surface is finely wrinkled longitudinally, the wrinkles gathering
strength and becoming crowded together at the inner angles of the
lateral plates. At the base of the left side are a few very small
areas of a rich ochre colour spotted with black. The inner lower
angle of the left side is rounded inwards, suggesting that the

154 MR. H. BOLTON ON INSECT-REMAINS | Febsrouas

raised median portion was incurved and shorter than the sides.
The whole outer margin was thickened.

Affinities.—The appearance presented by this pronotum some-
what suggests the prothoracic shield with wing-like expansions
of Lithomantis carbonarius.' The resemblance to that species is
little more than superficial : for, while in Dr. Woodward’s species the
lateral lobes are veined like the wings, in this case there is no trace
of veins, the surface being covered with longitudinal wrinkles, nor
is there any clear evidence of a rostral prolongation. On the other
hand, the recent Mantide and Lithomantis seem alone to possess
this form of prothoracic shield, so far as I have been able to
determine. Certainly it is not present in any fossil member of the
blattoids, nor have I seen anything suggestive of it among the
pronota of recent cockroaches. If the pronotal shield were of an
undoubted mantid type, one would naturally turn again to the wing-
impression, expecting to find its blattoid determination erroneous.
The fact, however, that the two central main veins throw off their
branches in opposite directions effectually disposes of any possibility
of affinities with Lithomantis. That the prothoracic shield is that
of a Lithomantis or allied form, which has been accidentally pre-
served in close contact with the wing of a blattoid, seems hardly
likely. Iam more inclined to think that the pronotal shield and
the wing-fragment are parts of the same insect, and that future
discoveries in older rocks may indicate that the apparent Litho-
mantid appearance of the pronotum points to a common origin
for the blattoids and the mantids.

HEMIMYLACRIS OBTUSA, sp. nov. (Pl. X, figs. 4 & 5.) ([Reg.
No. 24510. |

A stout, obtuse, rounded right wing, 23 millimetres long and 14
broad. The wing lies in a soft fire-clay full of Stigmarian rootlets,
and is distorted by pressure. It has been fractured obliquely
across the lower third and along the anal furrow.

The outer margin is well rounded, the inner, judging by the
course of the anal veins, being almost straight. The proximal
half of the sub-costal area is smooth, broadly triangular, and
11 millimetres long. The sub-costa is sunken, and passes in a
straight line from near the middle of the wing-base to the outer
margin, forking into two short branches just before reaching the
latter. On its outer side it gives off near the base two short
branches, the outermost of which forks once, and the inner twice,
before reaching the margin. Owing to the perfectly straight course
followed by the veins, the sub-costal area is long, nearly equal to
two-thirds of the length of the wing in fact, and separable into a
basal smooth area, and a distal one crossed by few veins.

The radius is large, much divided, and reaches distally almost to
‘tthe apical point. The lower half is characterized by a regular

1 H. Woodward, Q. J. G. 8. vol. xxxii (1876) pp. €0-65 & pl. ix, fig. 1.

Vol, 67.] FROM THE SOUTH WALES COALFIELD. 155

dichotomy. Arising from the middle of the base, the vein stands
out in relief for a very short distance, after which it becomes and
continues sunken. Its general course is arcuated forward to the
middle of the wing, after which it bends a little inwards, and then
again outwards in the marginal veins of the innermost branch. It
divides into two equal branches at a distance of about 6 millimetres
from the base, and these divide again at the same level 3 mm.
beyond the first division. Of the four branches thus produced, the
outermost passes straight outwards towards the margin and parallel
to the main stem of the sub-costa. It appears to die out before
reaching the margin. The inner branch of this bifurcation passes
staight out to the margin, giving off two smalier veins on its outer
side which also reach the margin, all the three marginal veins being
parallel to the sub-costa. The inner branch, which forks at the
same level, also possesses two dissimilar veins, the outer agreeing
in character with the adjacent vein of the outer branch; that is,
it continues straight out to the margin, giving off two lateral veins
on its outer side. All these branches of the radius pursue astraight
course. ‘The innermost gives off two simple branches passing out
to the apex of the wing, and then forks, the outer of the two
resultant veins forking again. The course of the marginal branch-
veins of the radius is such that the radial area must have extended
over almost the whole of the anterior third of the wing-tip.

The median vein is sunken along its whole length, and apparently
continuous with the cubitus at its base. The crumpling which the
base of the wing has undergone prevents accurate determination.
Appearances suggest that the cubitus first divides at the top of the
lower third of the wing, giving off a backwardly directed branch
which forks twice at least before reaching the hinder apical margin.
In all probability, the branch sends five or six veins out to the
wing-margin. Near the middle of the wing, two more inwardly
directed veins are given off, the innermost continuing unbranched to
the broken edge of the wing, and the other forking before the edge
is reached. The vein then continues almost straight out to near
the apical point. The marginal portion of the median area extends
from the wing-apex, or a little in front of it, to the inner border,
of which it forms the distal portion.

The cubitus has little if any share in the tip of the wing. The
cubitus is strongly curved inwards. It bifurcates soon after
leaving the media, the inner branch vein passing outwards and
inwards without division to a little distance above the middle of
the hinder margin. The more central branch-vein soon forks
again into two fairly equal divisions, the outer median one break-
ing up into four marginal veins, and the inner into three. The
marginal extent of the cubitus includes the distal third of the
inner wing-margin. All the veins are sunken.

The anal area is large, broadly triangular, and convex dorsally.
It is marked off by a strong arcuate furrow, the anal vein standing
out in relief. The subordinate anal veins are very numerous.
They consist of (1) a short stem, which sends off a simple inner

156 MR. H. BOLTON ON INSECT-REMAINS [ Feborena,

branch to the margin, and then bifurcates twice, the resultant four
veins pursuing a course parallel to the simple members of the main
stem, and filling up the space between it and the anal furrow ;
(2) of a series of seven or eight straight veins, only three of which
possess a single bifurcation. Not less than fourteen anal veins
impinge upon the wing-margin. The base of the anal area is
prolonged into a short, stout, subacute pedicle, presenting all the
features of an articular surface. The wing, considered as a whole,
is leathery in texture, and there is an entire absence of cross-veins
or wrinkles,

Affinities.—The essential features of this wing are its broad
and shortened character, the triangular sub-costal area, doubly-
branched radius, the backwardly directed branches of the media,
and the large anal area. This assemblage of characters is only to
be found in one family, that of the Mylacride. The somewhat
radial character of some of the anal veins, the backwardly directed
branches of the media, and the long anal area limit the specimen
to the genus Hememylacris. In this genus also the inner division
of the radius is much the largest, and covers most of the radial
area, a feature in which the specimen here described agrees. I
have, therefore, no hesitation in classing it as belonging to Hemi-
mylacris, It is abroader wing than H. ramificata, and the greater
humeral area is destitute of veins, while the marginal extension of
the cubital area is not so large, and the general course of those
veins more arcuate. It is, however, a closely related species, to
which I would give the name Hemimylacris obtusa.

Horizon.—Four-Foot Seam of Swansea, Gladys Colliery. 1 mile
east-south-east of Penller-gaer Church (Glamorganshire).

HEMIMYLACRIS coNVEXA, sp. nov. (Pl. VII, fig. 3.) [Reg.
No. 24512. ]

Proximal half of a tegmen, much distorted and crumpled at the
base. The part remaining does not exceed 10 millimetres in
length. The sub-costal lobe has been broken and crushed in
upon itself: it was apparently smooth. Very little is left of the
sub-costal area, which appears to have been triangular, and to
have run out upon the margin at about the level of the tip of the
anal furrow. Traces of two marginal veins are present.

The radius arises in the middle of the base, and almost imme-
diately bifurcates. The outer branch divides again into two
marginal veins, while the inner first sends off a long simple vein,
then passes straight outwards in the direction of the apical point
of the wing, bifurcating just before the broken edge of the wing is
reached. While the fragmentary marginal branches of the sub-
costa appear curved, those of the radius are straight. The inter-
vening areas are flat in both cases. ;

A comparatively wide interspace divides the radius from the
media. It is scarcely possible to separate the latter vein from the
cubitus with certainty, so little of the wing being present. I am

Vol. 67.] FROM THE SOUTH WALES COALFIELD. 157

inclined to regard the single vein shown next to the radius, as the
basal end of a comparatively small media. This vein-stem shows
a bifurcation at the end of the middle third of its visible length,
and a second bifurcation on the outer branch near the broken edge
of the wing. It is difficult to determine whether the next inner
long simple vein belongs to the media or not. It approaches the
base of the media very closely indeed, but, as I believe, does not
fuse with it. The crumplng of the wing at the critical point
prevents positive determination either way.

The next inner vein is a part or the whole of the cubitus. I
interpret it as the lower or inner division, regarding the long vein
previously noted as the outer branch of the cubitus. The inner
division consists of a stem gently arcuated. and bifurcating twice,
ending on the middle third of the inner margin in four branches.
The anal furrow follows a course parallel to the inner branch of
the cubitus. The wing has broken along the course of the furrow,
and thus obscured its characters somewhat. It can be determined,
however, that the furrow is shallow and the vein thin. The anal
area is crossed by three small veins arising from one basal point,
and radiating outwards to the margin. Owing to the fracture, the
anal area has become a little displaced inwards.

Affinities.—Owing to the fragmentary and crumpled condition
of the wing, the affinities are by no means easy of determination.
By far the most important features determinable are the almost
_ equal sub-costal and anal areas, the restriction of the radial area to

the outer half of the wing-apex, and the corresponding expansion
of the median veins over the inner half. The few anal veins dis-
tinguishable seem to radiate from one point. All these are features
characteristic of the family Mylacride of Scudder. The generic
relationships are clearly those of Handlirsch’s genus Hemimylucris,
and the correspondence with the lower half of that author’s
Hemimylacris ramificata is remarkably close. Differences there
are, but of specific value only. I may instance the few anal
veins in the South Wales tragment, and the clear suggestion of an
almost straight inner margin. Careful comparison with the
characters of EHtoblattina, Gerablattina, and Archimylacris have
satisfied me that it can be none of these, and I therefore place the
specimen in the genus Hemimylacris of Handlirsch.

Although the full characters of the wing cannot be determined,
it seems desirable to give the species a name, as it is clearly not
H. ramificata. I assign to it, therefore, the name of Hemi-
mylacris conveéxra.

Horizon.—Shales associated with the Graigola Seam. Clydach
Merthyr Colliery, Clydach Valley (Swansea Vale), Glamorganshire.

ARCHIMYLACRIs (ScHIZOBLATTA) OBOVATA, Sp. nov. (Pl. VII, figs. 4-6.)
[Reg. Nos. 24506 & 24507.|

A markedly obovate left tegmen, the portion preserved being
23 millimetres in length, and 10 mm. in greatest breadth. The

158 MR. H. BOLTON ON INSECT-REMAINS [| Feb. 19m;

whole of the anal and a portion of the cubital areas are missing,
as also a small portion of the base. The dimensions of the perfect,
wing are hardly likely to have exceeded 25 millimetres in total
length and 12 to 13 mm. in breadth.

The anterior margin forms a broad convex curve, almost straight
as it approaches the base, and more rounded towards the narrowed
and blunt apex. Beyond the apical point the inner margin is
complete for half of its length, and has a well-rounded convex
outline, much more pronounced than that of the outer margin.
The sub-costal area is narrow, somewhat strap-shaped, but widest
in the middle, and terminating acutely a ttle beyond the middle
of the outer margin. A little of the base of the sub-costa and
the proximal costal lobe are absent. The former gives off three
veins, the basal one remaining single to the margin, the second
giving off a simple basal branch and then forking just before
reaching the margin, while the outer and final branch bifurcates
near the middle of its length. ‘Traces of a more basal vein can be
seen, but Whether it is a still lower branch (which is most probable)
cannot be determined. All the branches of the sub-costa pass out
very obliquely to the margin. The areas between the secondary
veins are widest in the middle, and hollowed, the veins standing
out in relief.

The radius is much the largest of the series, being separated over
the greater part of its length by an unusually wide interval trom
the sub-costa. At a distance of 3 millimetres from the present base
of the wing, it divides into two diverging branches, each of which
again forks at a height of 4 mm. beyond the first bifurcation. The
first branch sends off a long vein, which forks before reaching the
margin, and approaches the outer vein of the sub-costa so closely
as to make the interval between them about equal to that of the
adjacent area. The inner division of the branch sends off, forward
and outwards, a long vein which forks almost on the margin;
passing forwards, it then forks at the level of the outer angle of
the sub-costal area, and runs on to the outer margin. The two
branches of the middle division pass out to the middle of the wing,
the inner branch being concave outwards. The outer branch
divides a little below the inner, and sends the resultant two veins
straight to the outer margin. The inner branch first sends a
simple undivided vein backwards, which reaches the margin
just below the apical point; a little farther out, a simple vein is
directed forward in advance of the apical point of the wing.
The area of the radius is thus large, and as it passes beyond the
apical point back to the inner margin, the area of the media is
correspondingly reduced.

The full character of the median vein is to some extent a
matter of conjecture, owing to the missing portion of the wing
having carried away the basal union of the veins. A portion of
the main stem is visible, from the level of the second double
bifurcation of the radius, and is seen passing straight out towards
the apex, until the middle of the wing is reached, where it divides

Vol. 67. | FROM THE SOUTH WALES COALFIELD. 159

into two equal branches which curve gradually backwards to the
inner border. On the inner side of the main stem, and dis-
connected from it, is a branch giving off a single long vein
from the level of the second bifurcation of the radius, and a little
farther out dividing into two equal branches. All three veins
follow the same general curve of the ultimate branches of the main
stem of the radius, and run out on to the inner margin. Basally,
their course is such that we should expect the axis to merge into
the main stem of the media, and I naturally assume that they
are a part of that vein. Strong presumptive evidence of such
a union is also afforded by the basal course of the next marginal
veins, which appear to be separated by an interval that widens
basally. The median area thus marked out is very small, and does
not occupy more than a fifth of the inner wing-margin.

The cubitus is represented by six marginal veins, of which only
the penultimate one to the apex is forked. Their basal direction
points conclusively to a common origin ; probably, however, only a
little over half of the whole vein is present. ‘There is no trace of
the anal portion of the wing.

The wing is thick, coriaceous in texture, and was somewhat
rounded on the upper surface. This roundness has been modified
in the lower half of the wing by a little crumpling from before
backwards. It is, perhaps, to the same shrinkage that we must
assign the transverse wrinkles present between the veins over
the radial and median areas. Unlike the purely transverse
wrinkles, so evident a feature in many of the Archimylacride,
those in the specimen here described are oblique to the veins, and
not at right angles. Where they are most conspicuous, as
in the marginal veins of the radius, they are seen to be very
irregular in character. In some places, a close-set series start
out from the side of a vein, and die out in the interspace. In
other places, sets of wrinkles are interrupted by smooth inter-
spaces, this arrangement occurring at haphazard. There are a
few, but not many, cases where the wrinkles anastomose.

Affinities.—There can be no doubt as to this specimen being
an Archimylacrid. Dr. Handlirsch, who has raised Archimylacris
to the dignity of a family, Archimylacride, has also in the same
paper * founded a new genus, Schizoblatta, and with the type-
species of this genus the specimen here described is in close agree-
ment. The points to which I attach importance are the following :—

In both, the sub-costal area extends for a short distance beyond the middle
line, the veins in each case passing out obliquely to the margin. A very wide
interval separates the stem of the sub-costa from that of the radius in the
middle of their length, and this area is narrowed distally in each case by the
approach of the marginal veins. The radius is a large and much branched
vein, and separates into two main divisions, which fork at the same level and
reach to the apical point of the wing—in our specimen just beyond it. The
media is relatively small, while the cubitus has few branches, passing very

1 * Revision of American Palzozoic Insects’ Proc. U.S. Nat. Mus. vol. xxix
(1906) p. 722.

160 MR. H. BOLTON ON INSECT-REMAINS [Feb. tort,

obliquely out, like those of the sub-costa, to the margin. The anal area in the
type, Schizoblatta alutacea, is long, attaining nearly half the length of the
wing. Inthe specimen here described the whole of this part is missing, as also
a part of the cubitus. The missing portion of the inner margin extends beyond
the middle of its length, and with a knowledge of how frequently the anal vein
determines the line of fracture, this extended broken area becomes significant.
The fact that our specimen does not wholly agree with the definition of the
genus, does not invalidate the species, as the definition is founded upon one
specimen of the type-species only. Dr. Handlirsch’s definition is as follows :—

‘Front wing elliptical, about two and two-fifths times as long as broad. Costal.

area. extending about three-fifths the length of the wing, with about nine or
ten normal veins; not expanded at the base. Radius divided into two prin-
cipal stems, the superior of which separates into six branches and the inferior
into eight, the majority of the latter ending in the apical border. The media
likewise divides into two main stems, the anterior of which forms five branches
and the posterior four, all of which fuse in the apical margin. The eight
branches of the gently vaulted cubitus take up the entire inner border. The
anal area attains nearly half the length of the wing. Cross-veins area not to be
distinguished, but instead there is a fine-grained leathery structure.’ (Loc. cit.)

I would suggest an emendation, basing the characters of the genus upon
the obliquity of the marginal veins of the sub-costa and cubitus, the presence
of a wide interval between the former and the radius, and the wide area
occupied by the latter. The division of the radius into two unequal branches,
together with its symmetrical double bifurcation, is also, I venture to think, a
feature of primary importance.

In the wide divergence of the radius and the media, the specimen
here described is in agreement with Scudder’s genus Spiloblattina ;
but in this case the veins do not again converge to enclose an elon-
gate or oval area.

Horizon.—Gwernau Level of the Mynyddislwyn Vein, near
Maes-y-cwmmer (Monmouthshire).

ARCHIMYLACRIS (ETOBLATTINA) HASTATA, Sp. nov. (PI. IX. figs. 1-3.)
[Reg. Nos. 24501 & 24502. |

An oblong, broadly elliptical, left tegmen, twice as long as broad :
the length of the wing being 33:4 millimetres, and its breadth
16°5 mm. A portion of the base of the wing and a considerable
portion of the distal and inner margins are missing; but sufficient of
the wing is preserved to make these measurements approximately
accurate. The wing has a strong outline, especially along the
anterior margin—partly owing tothe presence of a broad, shallow,
concave depression, which runs almost the whole length of the sub-
costal and radial areas, on their outer side, and causes the anterior
margin to be reflexed dorsally. Of the inner margin, only the
greater part of the anal border is left, although but little of that
portion which bounds the cubital area can be missing. The pos-
terior two-thirds of the apical margin are gone, the absence of
which gives an acute lobate appearance to the wing, negatived
by a closer study of the inner margin. In all prcbability the
apex was narrowly and bluntly rounded, more so than is usual in
forms of this group—though not wholly unknown, as, for example,
in Archimylacris acadica Scudder.

The most nearly related species appears to be Archimylacris

Vol. 67.] FROM THE SOULH WALES COALFIELD, 161

(Etoblatiina) venusta, but the differences are sufficiently strong to
merit specific rank, where, as in this group, specific identity is
wholly dependent upon wing-structure. ‘he sub-costal vein is
strongly curved proximally, reaching almost to the middle of the
base of the wing. Farther away it is parallel to the margin, and
then passes rapidly forward and outwards in an oblique line,
reaching the margin at the outer edge of the middle third of the
wing. The subcostal area is thus wide at the base of the wing, and
narrows outwards, ending in an acuminate peak against the tip of
the distal vein. It gives off anteriorly nine, possibly ten, branches,
of which the 4th, 5th, 6th, 9th, & 10th are forked, the 6th forking
twice. The direction of the veins becomes more oblique to the
margin from the base outwards, the last two being almost in a
straight line with the sub-costa itself. The sub-costal area forms
a shallow concave trough, bounded by the upturned margin an-
teriorly, and posteriorly by a flattened ridge which bears the bases
of the radius and the median vein. A wide interval separates the
sub-costa from the main stem of the radius, the interval being as
wide at the base as at the level of the first forking of the latter.
The first four branches of the sub-costa are slightly elevated above
the general surface, the rest being flat, or, in the outer branches,
sunken.

The main stem of the radius is gently arcuated, and follows
a course parallel to that of the sub-costa, until the first fork
is reached, when it begins to curve backwards, so that the two
anterior veins are in this region separated by an unusually wide
interval. The proximal third of the radius is strongly elevated,
as is also the first branch up to its bifurcation. The latter arises
at a point a little in advance of the level at which the first branch
of the cubitus is given off, and, curving first forward and then a
little backwards, passes out to the margin, giving off three forked
branches of considerable length in its course. The marginal veins
are parallel with one another, and with those of the sub-costa; and
so the greater part of the anterior margin is marked out into
eighteen to twenty strips with parallel sides. Beyond the first
bifurcation the radius forks twice, once just above the middle of
the wing, and again at a point apparently equidistant between the
first fork and the apical margin of the wing. The precise position
cannot be determined, owing to the alar structure being torn
away around the critical area. All the minor veins are sunken,
those of the anterior branch in the concave depression which
passes outwards from the sub-costal area, those of the posterior
branches passing across a flat apical area. The whole course of the
radius follows a somewhat sigmoidal curve, the latter becoming
flattened in the hinder portion of the radial margin.

The media arises in actual contact with the base of the radius,
or is united thereto. It rapidly diverges until it becomes parallel
with the inner branch of the radius, with which it keeps parallel
until the first forking is reached at the end of the first third of the

@: J. G. 8S. Noe 265. M

162 MR. H, BOLTON ON INSECT-REMAINS [Feb. 1911,

wing; beyond this point the media bends backwards, and follows
an almost straight course to the upper third of the inner margin,
giving off four branches on its anterior side. Of these, the first
forks a little above the middle of the wing, and probably the rest
forked also; but the wing is torn away over the hinder half of
the apical area, and this point cannot be determined.

The regularity of the minor veins over the whole of the rest of
the wing makes this bifurcation a certainty. Up to the first
branching, the media is raised in moderately high relief, in this
respect agreeing with the basal portion of the radius. Beyond the
first branching, the veins become sunken, the intervening areas
being gently convex. The median area stretches along almost the
entire hinder half of the apical margin, and apparently extends
forward to the actual apical point. ‘The area is much larger than
in A. venusta, owing to the backwardly directed main stem of the
media, and the short and arcuate cubitus.

The cubitus arises in close proximity to the bases of the radius
and media, and gradually diverges from the latter, the divergence
increasing up to the point at which the fifth branch is given off,
after which it approaches the media very gradually, but still
keeping a wide interval between the two. The width of this
interval opposite the proximal forking of the media is especially
wide. Ten branches are given off from the cubitus on its inner
face, only one of which, the proximal one, is forked. ‘This is also
a little arcuated at its point of origin, and then passes out to the
inner margin, bending very slightly towards the apex of the wing
in its outer half, as do all the rest.

The cubital area stretches from the end of the first third of the
inner margin to a little within the distal third. It is much shorter
than in A. venusta. The first anal vein is robust, elevated in its
basal half, and depressed in the distal portion. It lies in the
middle of a deep broad valley, being widely separated from the base
of the cubitus and the base of the succeeding anal vein. It is
strongly arcuated, much more so than any of the chief veins, while
it is marked off from the second anal by the swollen or tumid inner
flank of the trough in which it lies. It reaches the margin about
the end of the first third of the wing. Eleven other anal veins are
present, which diminish in strength and also increasingly approach
one another backwards. They are wider apart distally on the
wing-margin than at their bases, so that the smaller inner veins
appear to pass obliquely and in straight lines to the wing-
margin. The inner wing-margin over the anal area is almost
straight.

Viewing the wing asa whole, one is at once struck with the
appearance of great muscularity, shown in two oblique ridges: an
anterior one passes forwards and outwards, and bears upon its
crest the main stem of the radius, being bounded in front by the
base of the sub-costa, while upon its hinder face lie the bases of
the median and cubital veins.

Vol. 67.] FROM THE SOUTH WALES OOALFIELD. | 163

The hinder oblique ridge follows the course of the second anal, the
first anal vein bounding its anterior border. Its hinder border is
not detined, the convexity dying out gradually over the anal area.
A median and less evident ridge carries the middle portion of the
cubitus, and lies a little in advance of the other two. The whole
surface is covered with a close-set series of narrow wrinkles at right
angles to the veins. They are most evident over the anal area,
where many of them fork between the veins, and also pass directly
over the latter in places. They are least evident over the sub-costal
and radial areas.

Affinities.—In the strongly arcuate outer margin and almost
straight inner margin, the specimen agrees with Anthracoblattina
spectabilis of Goldfuss. The sub-costal vein is not, however, parallel
to the anterior margin, while its width at the base is more than a
third that of the wing, whereas in A. spectabilis it is but a quarter.
The radius forks much nearer the base, being subdivided practically
into two main divisions. The cubitus is comparatively simple,
and only the lower branch is forked, whereas in A. spectabilis this
vein forks twice, and the succeeding three branches also fork.
A. spectabilis is a much larger wing, having a length of 44 mm.,
its estimated length when complete being 54 mm., and a breadth of
22 mm., the present species being about 33 mm. in total length as
now shown, but when perfect probably about 40 mm. When
compared with Archimylacris ( Etoblattina) venusta mihi, it exhibits
an equally close correspondence in shape, and in the origin of the
veins near the middle of the wing. Considerable differences exist,
however, in the sub-costal area, that of A. venusta being the longest ;
the branches of the radius in the latter are sixteen or more in
number, in the South Wales specimen there are not more than ten
or eleven, and the latter reach the wing-margin very obliquely.
The cubitus is a much longer vein in A. venusta, reaching the hinder
part of the apical border, while in this specimen it runs out to the
inner margin, the apical area being entirely occupied by the radial
and median areas. A careful comparison with other species shows
a greater divergence in structure, and I therefore regard this as
a form closely allied to A. venusta, but with decided specific
differences. The powerful muscular ridges at the base of the wing,
the marked convexity of the outer margin, and its upwardly reflexed
edge are characters peculiar to the species, and mark it off from all
other species that I have seen.

Owing to its general spear-shaped form, I have applied to the
specimen the name of Archimylacris (Etoblattina) hastata,

Horizon.—Gellideg Level of the Mynyddislwyn Vein, near
Maes-y-cwmmer (Monmouthshire).

ARCHIMYLACRIS sp. indet. (PI. X, fig. 3.) [Reg. No. 24503.]

A fragmentary blattoid tegmen showing the middle third of the
alar area, the proximal portion being concealed under a Cordaites
leaf, and the outer third missing.

. m2

164 ; MR. H. BOLTON ON INSECT-REMAINS [ RebS toner

The specimen is much too fragmentary for any attempt at specific
determination. The sub-costa is represented by three branches,
two of which fork low down, and therefore presumably near their
points of origin. The single vein, which is the lowest, may be the
upper member of a forked vein similar in character to the other
two. The veins stand out in relief, the interspaces being flat.
There are indications that the outer margin was bent downwards.

Judging from the course of the veins, which are very oblique, the
radial area extended for a considerable distance along the outer
margin. The radius is represented by three branches, the outer two
forking, and the fork of the first branch being at a lower level
than the second. ‘The veins are sunken, well defined, and with flat
interspaces as in the case of the radius. The direction is almost
straight outwards, and there can be no doubt that the radial area ~
reached the apical point of the wing.

The media shows five branches, the inner two converging towards
a common point basally. They represent, therefore, the secondary
branching of one of the lower offshoots. A somewhat wide interval
separates the radius from the media, and the interspaces between
the branches of the latter are narrower than those of the radius,
but not so narrow as those of the sub-costa, which are the smallest.
The general course of the media is outward and backward, the
direction being such as would bring the branches out upon the
margin behind the apical point. The median area probably included
the inner half of the marginal tip of the wing.

The cubital portion of the wing is partly obscured by a much
wrinkled superficial layer, the wrinkles in some cases passing
straight across between the veins, and in others being thrown into
erenulated lines, the convexities of which are directed basally.
Some of these crenulated wrinkles pass across the interspaces from
one vein to another, while others stretch across two interspaces.
Over the two outer veins, two sets of straight wrinkles intersect one
another, forming a small patch of irregular network. The general
effect of the wrinkles is similar to that which would be produced if
an easily separable epidermis or superficial layer had been pushed
towards the base of the wing. |

The inward inflection of the wrinkles at the veins indicates that
the outer layer was attached at equidistant points along their
length, while the fact that wrinkles which dip into the veins may,
and occasionally do, die out in the next interspace, would seem to
show that a wrinkle is a superficial corrugation, and‘ not a lateral
commissure of the veins themselves. The latter view is also nega-
tived by the two crossed sets of wrinkles on the two outer veins.
Seven cubital veins are present, the four inner being simple so far
as shown, and the three outer arising from a common stem. The
interspaces are convex. There is no trace of the anal area.

Scudder and others have commented upon the general association
of the wings of blattoids with leaves of Cordaztes. The base of

Vol. 67.1 FROM THE SOUTH WALES COALFIELD. 165

the wing in this case was concealed by a leaf of Cordaites, and
others occur upon the same slab of shale. While Carboniferous
blattoids may have been wholly phytophagous, it is interesting to
note that all the leaves of Cordaites (in the present case) are
impressed with shallow pits, which show faint traces of a spiral.
I have, in very many previous instances, found that such pits
owed their origin to attached shells of Spirorbis pusillus. Whether
these leaves were partly submerged in water during life is an open
question; but, in all cases, the plant-tissues of the pittings are
depressed, and are accurate impressions of Spzrorbis. If the
Carboniferous blattoids were not wholly vegetable feeders, the
occurrence of Spirorbis pusillus upon the Cordaites may supply a
reason for their frequent association.

The character of the wing-fragment is typically that of an Archi-
mylacrid. It was undoubtedly broad, and the chief veins were
well defined, deep, and distinct in character one from the other.

Horizon.—Gellideg Level of the Mynyddislwyn Vein, near
Maes-y-cwmmer (Monmouthshire. )

GERABLATTINA (APHTHOROBLATTINA) suLcATA, sp.nov. (Pl. VIII,
figs. 1-3.) [Reg. Nos. 24504 & 24505.]

Greater part of a right tegmen. Under surface alone shown.
Only a short portion of the outer margin of the wing is preserved,
an estimated two-thirds of the middle, and a small portion of the
anal area. Although the wing is thus fragmentary, it is fortunate
that the parts preserved include the sub-costal angle and the
greater part of the base with slight evidences of attachment.
The inner sub-costal angle is much produced, bluntly rounded, and
very broad, forming apparently a full third of the width of the
base. The angle bends sharply inwards to the point of attachment,
a small portion of the latter forming a narrow ill-defined neck
projecting outwards from the middle of the wing-base.

The anterior margin has the appearance of having been thickened
or infolded. The inner portion of the triangular sub-costal area is
smooth, and separated from the venated portion by an oblique
ridge arising near the base of the sub-costa, and passing obliquely
forwards and outwards to the margin. The sub-costa is thin,
elevated basally, and somewhat crenulated, doubtless owing to post-
mortem changes or pressure. Its course, so far as can be judged,
was parallel to the wing-margin, and in the portion exposed five
branching veins are shown, all of which fork very close to the
main stem. All the branches of the sub-costa pass out very
obliquely, pursuing a course which would indicate a sub-costal area
occupying nearly all the outer margin. The areas between the
veins are flat, except in the angles of the forks, where they become
convex.

The radius follows a course parallel to the stem of the sub-costa,
up to the point at which it gives off the first forward branch ;

— 166 _ MR. H. BOLTON ON INSECT-REMAINS [Feb. 1911,

beyond this point, the branch vein approaches the radius a little. ,
The main stem of the radius follows a course parallel to the
sub-costa, the parallelism being maintained by the first branch vein
and the outer branch that results from its bifurcation. The portion
of the radius preserved shows six branches, the first and third of
which are forked. Beyond the first forking the main stem of the
radius bends gently backwards, up to the middle of its length, ,
where it begins to curve very slightly forward. ‘The general
direction is such, that in all probability the scapular area extended ,
a little backwards behind the apical point of the wing.

The median vein arises quite close to, but is totally distinct
from, the radius. The media is the least evident of all, and its
course, especially in the basal half, is only determinable with diffi-
culty. It is slightly convex outwards in its lower half, then passes
straight to the apical margin. Four parallel branches are shown,
one or more almost certainly bifurcating before the margin was
reached. This is purely conjectural, the apical portion of the wing
being broken away. The first two-thirds of the length of the
media is regularly curved, the outer third passing in a straight line
to the margin. The distal portion of the wing being missing, the
full extent of the median area cannot be determined, but sufficient
is present to show that the area did not extend outwards to the
apical point, reaching the margin at about the middle distance of
the lower outer half of the margin.

The cubital vein is but faintly outlined proximally, where it is
almost in contact with the anal vein. It gives off eight backwardly
directed and parallel branches, only the third showing bifurcation.

The anal furrow is broad and shallow at the base, passing back-
wards to the inner margin in a narrowing groove and by a wide
and gentle curve. As a result, the anal area is unusually long,
being quite a third of the length of the wing. It is somewhat
convex proximally, owing to the raised, rounded inner border
of the anal groove, but more remotely becomes slightly hollowed.
Five subsidiary anal veins are distinguished, in addition to the
primary one. Of these, the first and second fork—the first a little
below the middle of its length, and the second at about two-thirds
of the length. All the veins are sharp and in good relief. The
wing-border all along the inner margin is curved ventrally, so that
the full course of the veins to the margin cannot be followed. Not
much, however, of the wing can be hidden, and probably not more
than three anal veins at the most are thus obscured. The whole of
the anal area is covered with multitudinous fine transverse wrinkles,
anastomosing in all directions between the veins. So abundant are.
these branches and fusions of the wrinkles, that in some portions
ot the area they assume a fine reticulation.

The portion of the wing preserved has a length of 38 millimetres,
and a breadth of 16 at its widest part. There can be little doubt
that the perfect wing had a length of at least 45 millimetres, and

Vol. 67.] FROM THE SOUTH WALES COALFIELD, 167

a breadth of 25. Transverse wrinkling occurs over the whole
wing, the wrinkles anastomosing between the veins. Although it
cannot be stated as a positive fact, the bases of the media and
cuhitus appear to have had a common root, or to arise in actual
contact with the primary anal vein, which is much stouter than
either. Both the media and the cubitus are weaker veins than any
others of the series. The slight indication of the anterior margin
of the wing in the basal sub-costal area shows that that margin
was convex.

Affinities.—In the general characters of the veins this spe-
cimen shows an agreement with Scudder’s Gerablattina (Aphthoro-
blattina of Handlirsch), the points in common being the weakly
developed sub-costa, especially in its lower half, and the apparent
union of the bases of the radius, media, and cubitus with the first
anal vein. In Secudder’s G. fascigera this union is clear, and con-
tinues along the middle line of the wing for some distance ; while
in the specimen here described the general structure points to a
common root of no great length. In the character of the surface-
wrinkles and a subordinate reticulation there is also agreement.
The veins arise a little above the middle of the wing, a feature
more indicative of Archimylacris, but scarcely confined to that
family. I consider that the wing agrees most closely with the
genus Gerablattina as defined by Scudder,’ and with that section
which Dr. Handlirsch has erected into a new genus under the name
of Aphthoroblattina,* although the difference in development of the
united veins constitutes a wide difference between this species and
Aphthoroblattina (Gerablattina) fascigera, which Handlirsch takes
as the type-species of his new genus. 1 propose for this species
the name sulcata.

Horizon.—Gwernau Level of the Mynyddislwyn Vein, near
Maes-y-cwmmer (Monmouthshire).

ORTHOMYLACRIS LANCEOLATA, sp. nov. (Pl. X, figs. 1&2.) [Reg.
No. 24511.]

A left wing 23 millimetres long and 10 wide, elongate-lanceolate,
and tapering from the outer and inner margins to the subacute
apex. Both margins are slightly convex, the greatest width of the
wing being at the distal end of the anal area. The apical portion
of the wing has been bent inwards, producing an irregular cross-
wrinkle. In its uniform tapering towards the apex, and the long
bluntly-pointed appearance thus produced, the wing departs from
the typical blattoid type, this departure being also emphasized by
the uniform convexity of the upper surface and the character of
the chief veins, which we shall presently consider.

1 * Paleozoic Cockroaches’ Mem. Boston Soc. Nat. Hist. vol. iii, pt. 1
(1879) p..97.

2 «Revision of American Palzozoiec Insects’ Proc. U.S. Nat. Mus. vol. xxix
(1906) p. 719.

168 . MR. H. BOLTON ON INSECT-REMAINS [Feb. rort,

The sub-costal area is a little less than half of the length of
the outer margin, broadly triangular, and only sends six veins to
the margin. The sub-costa is thin, sunken, and gives off three
forked branches which pass out in straight oblique lines. The
area of the sub-costal or humeral lobe is smooth, and the outer
marginal edge, up to the termination of the sub-costal area, is
slightly upturned. The first two branches of the sub-costa arise
very low down.

The radial vein has numerous branches, and its area occupies
the greater portion of the fore part of the wing, the most distal
vein reaching the margin a little short of the apical point. The
main stem is thin, sunken, and divided into four principal branches,
the first three of which are doubly forked, the last forking only
once. The main stem has a slight sigmoidal curve, being directed
forward over the first third of its length, backwards over the
middle third, and forward and outwards over the last branch.
All the veins are very oblique and arise low down; and thus,
notwithstanding the narrowness of the wing, they are relatively
long. A wide interval separates the outer branch of the sub-costa
from the lower innermost branch of the radius, the interval being
widest in the middle and narrowing at the wing-margin and at the
base.

The media has the same general characters as the previously
described veins, but does not branch until the middle of the wing
is reached, and on a level with the third branching of the radius.
The proximal branch curves very slightly backwards and then
forward, forking twice, the hinder of the distal veins reaching
the margin in the apical point. Before doing so, it forks, then
reunites, the two branches enclosing a long lenticular area. Beyond
the union, it forks again quite close to the margin. The second
branch of the media is single throughout its length, and is a very
long vein, almost half the length of the wing. A little beyond the
origin of this second branch, the main stem divides into two, the
inner or proximal one passing out undivided to the inner margin,
which it reaches some little distance behind the apical point. The
distal branch is somewhat remarkable: branching at about half
the length of the proximal branch, it sends off two unequal veins.
Of these, the anterior is long, and bent forwards in a strong curve,
reaching the margin at the apical point, and but little removed
from the tip of the long simple vein that: has been already de-
scribed ; the inner branch is short, and passes obliquely outwards
to the inner margin, leaving an unusually wide double wedge-
shaped area between the two branches. As a result of this curious
disposition of two branches having a common origin, a large section
of the inner apical margin is destitute of veins.

The cubitus arises near, or may be united to, the base of the
media. This isa point which cannot be determined, the wing-base
being broken away. It at once divides into two main branches, the

WolG7.] FROM THE SOUTH WALES COALFIELD. 169

outer being simple and forking once far forward, after which the
branches curve gently backwards and then outwards to the margin.
The inner ramus gives origin to three branches, the first and third
being forked, the central simple and unbranched. ‘The veins follow
a similar course to those of the outer ramus.

The anal area has been broken away along the line of the anal
furrow, the latter passing in an open curve from a little below the
middle of the base of the wing outwards to the margin, which it
reaches a little below the middle line.

Affinities.—The distinguishing feature of this wing is the
basal branching of all the veins with the exception of the median,
and the width of the area occupied by them at their origin.
Usually, in the blattoid wing, the chief veins arise as nearly as
possible in contact with one another; or else two or more may have
a common stem. In this case they are well separated, and are
' spread over nearly a third of the wing-base. Another feature of
unusual character is presented by the wide interspaces between the
veins in the middle of the wing. These wide interspaces are well seen
between the lower ends of the branches of the radius, the wide
interval between the main stem of the latter vein and that of the
media, and again between the latter in the middle of its length and
the outer branch of the cubitus. While this open spacing is a
distinctive character of Handlirsch’s family Spiloblattinide, it is
not confined to that group; and, as it is accompanied in the present
instance by a markedly triangular sub-costal area, in place of a
strap-shaped one, it cannot be assigned to any genus of that family.
It may be noted, however, that in general form, and in wide inter-
spaces, it agrees with the genus Atactoblatta. Believing that the
character and the mode of branching of the veins furnish the
most reliable evidences of relationship, I am of opinion that the
relationships of this form must be sought for among the members
of the family Mylacride of Scudder. Within this family Dr. Hand-
lirsch constituted a new genus Orthomylacris, with the definition of
which the specimen closely agrees. His definition is as follows :—

‘Front wing two to two and a third times as long as broad, of subcordate
outline. Costal area extending one-half to two-thirds the length of the wing.
Radius continuing to the apical border, with a variously large number of offshoots
branching forward. ‘The superior branch either simple or forked, more rarely
strongly compound. Media with few veins directed obliquely backward to the
apical and inner borders. Cubitus never continuing to the apical margin,
with few branches. Anal area very long, at least twice as long as high, and
extending two-fifths to one-half the length of the wing, with numerous more

or less compound veins. Structure leathery, more or less distinctly cross-
wrinkled.’ (Proc. U.S. Nat. Mus. vol. xxix, 1906, p. 768.)

Only a very few somewhat oblique cross-wrinkles can be detected
upon the specimen on the inner side of the apex. Elsewhere the
wing-structure is smooth or somewhat granular, the granularity
being perhaps due to the impress of the material in which the wing
lies embedded. The surface of the wing is flatly and regularly

170 MR. H. BOLTON ON INSECT-REMAINS |Feb. rorr,

convex, with the exception of the inner portion of the sub-costal
margin, which is slightly upcurved. No definite trace can be
detected of an anal furrow.

Owing to its marked elongate character and doubly convex
margins, I apply to this form the name of Orthomylacris lan-
ceolata.

Horizon.—Shales associated with the Graigola Seam, Clydach
Merthyr Colliery, Clydach Valley (Swansea Vale), Glamorganshire.

LAMPROPTILIA TENUITEGMINATA, sp. nov. (Pl. X, fig. 6.) [Reg.
No. 24509. |

A right hinder wing of large size and considerable tenuity. The
greatest length and breadth are 29 millimetres and 7 mm. respec-
tively. The tenuity of the wing is so great that underlying plant-
remains can be seen and traced easily. A leaf of Lepidophyllum
majus overlies and partly conceals the base.

The venation is at first sight of the same general type as that of
a blattoid tegmen; the branching is more extensive, however,
and the distal expansion of the wing-surface much greater. ‘The
wing appears to have been somewhat quadrangular in outline,
with a sinuous inner margin, and the base is much broader than in
the ordinary form of blattoid. The outer margin is probably repre-
sented by a shadowy line along the middle third of the outer wing-
margin, in which case it must have been fairly straight, in this
region bending in a well-rounded angle to the tip of the wing, and
the latter similarly merging in the delicate sinuous inner border.

The sub-costal area is narrow, strap-shaped, and probably ex-
tended over the whole length of the outer margin. No definite
trace of veins can be discerned upon it.

The radial vein divides low down near the base into two rami,
the outer being the smallest. The latter first divides about the
middle of the wing, sending off a simple branch which reached
the broad apical margin, and curving gently backwards as it
approaches the latter. Farther out, the radius sends off at, |
equal distances two more simple branches, which follow a course
parallel to the first. It is then continued as a small vein, which
bends somewhat abruptly inwards at the point of forking, and
approaches close to the outermost marginal vein of the inner
ramus. Its backward sweep is thus greater than that of the
other marginal veins of the same ramus, and its course must have
brought it out upon the margin near the middle point of the tip of
the wing. The inner ramus of the radius forks low down, much
nearer the base than the corresponding bifurcation of the outer
ramus, and the two branches into which it is divided fork again
nearly at the same level near the middle of the wing. Of the four
branches thus produced, the outermost remains simple to the margin,
the inner branches forking on a level with the second branching

~

Vol. 67.] FROM THE SOUTH WALES COALFIELD. 171

of the radius. The course of the veins is irregular, the interspaces
widening and narrowing along their length. This may be due to
distortion of the wing when deposited upon the mud. The marginal
veins arising from the radius extend over the whole inner portion
of the wing-tip, owing to their strong backward course in the final
portion of their length, the direction being almost at right angles
to the basal portion of the stem-vein.

The media divides almost at its point of origin, the outer branch
forking a little below the middle of the wing, beyond which the
veins become so attenuated that their course is but faintly outlined
to the distal end of the inner margin. ‘The inner vein forks low
down, and again in the middle of the wing, the resultant four
branch-veins thinning out much as do those of the outer branch.
They are impressed as very faint lines, the continuity of which
cannot be traced back to the inner margin.

The course of the cubitus is obscured by a reed-like plant which
underlies it. It is much less distinct than the rest, only two basal
portions being distinguishable.

The anal area is filled by a broad series of thread-like veins,
which sweep outwards and backwards in a fan-like form to the
inner margin, and occupy fully one-half of it. The innermost
anal veins are quite geniculated close to their origin, so that
they bend abruptly backwards. They all seem to arise from a
comparatively few (four to six) stems.

The inner margin of the wing to a third of its total depth is
quite filmy and veil-like, the veins crossing the area as faint
shadowy lines. The outer two-thirds is more strongly impressed,
while indications are present which lead to the inference that in
the broad base of attachment the stem-veins were more than
usually robust. No trace of transverse veins, of wrinkles, or of a
reticulation is shown.

The specimen les in a small fragile block of brown mudstone or
shale, crowded with plant-remains, among which I have distin-
guished Lepidophyllum majus and Cordaites.

Affinities.— Hind wings of insects are so rarely found in the
Coal Measures, that generic or specific determination is a matter of
no small difficulty. Unless found in association with the tegmina,
it may well happen that they may be referred to a different genus.
Dr. Sellards,* who devotes more than usual attention to blattoid hind
wings and also figures several, says that they did not fold longi-
tudinally as in recent forms, and that cross-veins are not known.
The inner border was full and well rounded, making the wing
broad in proportion to its length. Dr. Sellards’s types may best be
described as broadly ovate, and much unlike the form here described.
They are indeed but little removed from the tegmina in shape.
Scudder, Handlirsch, and others have hardly touched this question,

1 «Structure of Fossil Cockroaches’ Amer. Journ. Sci. ser. 4, vol. xviii

(1904) p. 119.

172 MR. H. BOLTON ON INSECT-REMAINS [ Feb: 199%,

and have frankly avowed that, in the present state of our know-
ledge, the classification of the Paleozoic cockroaches is largely
artificial and a matter of convenience. That such is the case I
believe few will venture to dispute.

After a considerable amount of comparison and research, I
have abandoned the possibility of blattoid affinity, and find the
nearest analogues to this wing in the genus Lamproptilia of
Charles Brongniart. That author described and figured two species,
L. gran@eury. and L. stirrupi,* which show a close agreement
with the form here described. ‘This is more closely related to
L. stirrupi than to LZ. grand@’euryi, it is more quadrangular in
outline than either, and the costal area is much broader. The anal
portion of the wing is of greater tenuity, and occupies fully half
of the inner margin, while the latter is almost straight in its distal
half. To distinguish it as a species, I assign to it the name of
Lamproptilia tenurtegminata.

Horizon.—Level in No. 2 Rhondda Seam, 12 miles north-east
of Resolven Station (Glamorganshire).

LV. GmenERAL OBSERVATIONS.

One feature of some interest is the marked association of these
blattoid wings with vegetable remains, especially the leaves ot
Cordaites and the pinnules of Newropteris. In several cases the
wings are interbedded with Cordaites leaves. The wing of Hemi-
mylacris obtusa occurs in a typical underclay, and that of Lampro-
ptilia in a yellowish-brown shale crowded with plant-remains.
The proximity of the deposits to a land-surface seems evident. I
have elsewhere alluded to the presence of sunken pits in the
Cordaites leaves, and the possible bearing which these may have
upon the use of Spirorbis pusillus as food by the blattoids. Scudder,
Sellards, and several others have noticed the association of blattoids
with fossil plants, Dr. Sellards suggesting that they were fond of
moist low places with abundant vegetation, such as would be found
along the banks of rivers and marshes.?. From such situations the
transference of dead insects and loose vegetation into the water
would be inevitable.

Any attempt to discuss the relationship of these South Wales
blattoids with those of North America or Europe could only be
based upon somewhat vague conjectures. The presence of Archi-
mylacrid and Orthomylacrid forms, no less than the presence of
Lamproptilia, is indicative of a considerable advance in insect
development in this country beyond the more primitive palezo-
dictyopteran types; and from their abundance we may fairly

1 «¥tudes sur Je Terrain Houiller de Commentry’ vol. iii (1893) pp. 467-70
& pl. xxxv (19), figs. 7-9.

2 WH. H. Sellards, ‘ Structure of Palzozoic Cockroaches’ Amer. Journ. Sci.
ser. 4, vol. xviii (1904) p. 122.

Vol. 67.) FROM THE SOUTH WALES COALFIELD. 173

expect to find more lowly types in the Lower Series of the South
Wales Coalfield at some distant date, or even traces of their presence
in rocks of Older Palaeozoic age. Their occurrence may also be
regarded as indicating the possibility of a terrestrial fauna some-
where in the South Wales Coalfield.

In conclusion, I wish to acknowledge my indebtedness to the
Director of H.M. Geological Survey, who placed the specimens in
my hands for study ; to Dr. Aubrey Strahan, F.R.S., for information
respecting localities and the stratigraphy of the South Wales Coal-
field; to Mr. J. W. Tutcher for his kindness in photographing the
specimens amidst the pressure of much other work; to Mr. R. E.
J. Bush, A.R.C.A., who has prepared the wing-diagrams with great
skill and accuracy; and to Mr. John Pringle, of the Geological
Survey.

EXPLANATION OF PLATES VII-X.
[The photographs are by Mr. J. W. Tutcher, and the line-drawings by
Mr. R. E. J. Bush, A.R.C.A. All the figures are magnified 2°6 diameters;

the specimens are in the Museum of Practical Geology, Jermyn Street,
London, S8.W.]|

Prats VII.
Fig. 1. Figure of Gerablattina arcuata Sellards, to illustrate the terminology
of the wing :—
Redtenbacher. Heer.
I. Costa. I. Marginal.
Il. Sub-costa. IT. Mediastinal.
III. Radius. III. Scapular.
IV. Media. IV. Externomedian.
V. Cubitus. V. Internomedian.
VI. Anal veins. VI. Anal veins.

The terminology of Redtenbacher is followed in the text.

2. Archimylacris sp. indet. and pronotum. [Reg. No. 24508.|] (See
pp. 152, 153.)
Horizon.—Mynyddislwyn Vein, Gellideg Level, near Maes-y-
ewmmer (Monmouthshire).
3. Hemimylacris convexa, sp. nov. [Reg. No. 24512.] (See p. 156.)

Horizon.—Shales associated with the Graigola Seam, Clydach
Merthyr Colliery, Clydacn Valley (Swansea Vale), Glamorganshire.

Figs. 4 & 5. Archimylacris (Schizoblatta) obovata, sp.nov. [Reg. Nos. 24506 &
24507.] (See p. 157.) Left teezmen and impression. A large portion
of the inner half of the wing is missing. The impression is more
complete.

Horizon.—Mynyddislwyn Vein, Gwernau Level, near Maes-y-
ewmmer (Monmouthshire).

Fig.6. Diagram showing the course of the veins in Archimylacris (Schizo-
blatta) obovata.

OO eer a eee ey th! Ne eg) Pe eee

174 INSECT-REMAINS FROM THE SOUTH WALES COALFIELD. [ Feb. 1911.

Prats VIII.

Figs. 1 & 2. Gerablattina (Aphthoroblattina) sulcata, sp. nov. [Reg. Nos.
24505 & 24504.) (See p.165.) Greater part of the right tegmen and
impression of the same. The under surface of the wing is shown.

Horizon.—Gwernau Level of the Mynyddislwyn Vein, near Maes-
y-cwmmer (Monmouthshire).

Fig. 3. Diagram showing the course of the veins in Gerablattina (Aphthoro-
blattina) sulcata.

Puate IX.

Figs. 1 & 2. Archimylacris (Etoblattina) hastata, sp. nov. [Reg. Nos. 24501 &
24502.] (See p. 160.) Impression of and greater part of the
left tegmen. ‘The proximal portion and the inner half of the apex of
the wing are missing.

Horizon.—Gellideg Level of the Mynyddislwyn Vein, near Maes-
y-cwmmer (Monmouthshire).

Fig. 3. Diagram showing the course of the veins in Archimylacris (Ktoblattina)
hastata.

PuatE X.

Fig. 1. Left tegmen of Orthomylacris lanceolata, sp. nov. [Reg. No. 24511.]
(See p. 167.) A portion of the base of the wing and the whole of the
anal area are missing.

Horizon.—Shales of the Graigola Seam, Clydach Merthyr Colliery,
Clydach Valley (Swansea Vale), Glamorganshire.
Diagram showing the course of the veins in Orthomylacris lanceolata.
. Archimylacris sp. indet. [Reg. No. 24503.] (See p. 163.) <A frag-
mentary blattoid tegmen showing the middle third of the wing-area,
the rest being concealed under Cordaites leaves. The impressions
made by the attachment of shells of Spirorbis pustllus can be seen
upon the Cordaites leaf to the left. ,
Horizon.—Gellideg Level of the Mynyddislwyn Vein, near Maes-
y-cwmmer (Monmouthshire).

4. Right tegmen of Hemimylacris obtusa, sp. nov. [Reg. No. 24510.]
(See p. 154.)

Horizon.—Four-Foot Seam of Swansea Gladys Colliery, a mile
east-south-east of Penller-gaer Church (Glamorganshire).

. Diagram showing the course of the veins in Hemimylacris obtusa.

. Right hinder wing of Lamproptilia tenuitegminata, sp. nov. | Reg. No.
24509.| (See p. 170.) The extreme tenuity of the wing and the
almost straight inner ean are well seen in the figure.

Horizon.—Level of No. 2 Rhondda Seam, 14 miles north-east of
Resolven Station (Glamorganshire).

So Or

Quart. JOURN. GEOL. Soc. VOL. LXVII, PL. VII.

3

No. 24512.)

(

Bemrose Lid., Collo., Derby.

GERABLATTINA, ARCHIMYLACRIS, AND HEMIMYLACRIS.

J. W. Tutcher, Photogr.

ae i

eo

;
#

QUART. JOURN. GEOL. Soc. VOL. LXVII, PL. VIII.

} Derby.

Bemrose Ltd., Collo.

GERABLATTINA (APHTHOROBLATTINA) SULCATA.

J. W. Tutcher, Photogr.

te

mos

i % : ‘ ea % ae i ore. t
e \ e : 2, . i eco ree
‘ his § Pet ty
v - mk >
X ects f
: ‘

J. W. Tutcher, Photogr.

QUART. JOURN GEOL. Soc, VoL. LXVII, PL, IX.

Bem*yrose Lid., Collo., Derby.

ARCHIMYLACRIS (ETOBLATTINA) HASTATA.

ros

‘AWN a) ante Melee tae

cra)

:
: QuarT. JOURN. GEOL. Soc. VoL. LXVII, PL. X.
:

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J. W. Tutcher Photogr. Bemrose Litd., Collo., Derby.
ORTHOMYLACRIS. ARCHIMYLACRIS, LAMPROPTILIA, ETc.

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Pages
Proceedings of the Geological Society, Session 1910-11 ...........cecseceseeeeeees i-viii
PAPERS READ.
Page
1. Mr. L. Richardson on the Rhetic and Contiguous Deposits of West, Mid,
and Part of East Somerset. (Plates I-IV) «............cccseneeccssecseeeerens 1

2. Mr. R. L. Sherlock on the Relationship of the Permian to the Trias in
Nottinghamshire, “(Plate V))-\ .......ss.cec.csennessaconesscscdsctes see ee ee eee 75

3. Dr. W. F. Hume on the Effects of Secular Oscillation in Egypt during the
Oretaceous and Eocene Periods. (Plate VI) .........cs.sccscsecssecesceoeses 118

4, Mr. H. Bolton on a Collection of Insect-Remains from the South Wales
Coalfield. (Plates VIT-X) ...............00. see guna adi aca teeeaa cate eeee een 149

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Vol. LXVII. MAY 3lsr, 1911. No. 266.
Part 2.

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Elected February 17th, 1911.

Yay aS

PrestVent.
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STANDING PUBLICATION COMMITTEE.
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Mr. H. A. Allen. Dr. J. HE. Marr.

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Dr. J. V. Elsden. Prof. 8. H. Reynolds.
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EVENING MEETING OF THE GEOLOGICAL SOCIETY
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Sresston 1910-1911.

1911.
Wednesday; dune o..c.c.e cette 14*
[Business will commence at Hight 0 Clock precisely. |
The asterisk denotes that the Council will meet on that date.

Vol. 67.] THE SKOMER VOLCANIC SERIES. 175

5. The Sxomur Votcanic Serres (Pemprokesuire).' By Herperr
Henry Tuomas, M.A., B.Sc., F.G.S. (Read January 25th,

1911.)
[Piarr XI--Georocican Mar. ]
ConTEnTs.

Page
Pig be. 175
PERM Os Le TG), ee 177

III. The Stratigraphical Relations and Age of the
SS een een eer acessk<cwcesehecssensceses 179
DY 7) Rte Wole states bese toc n2<. och aeanscesstdacesecess ss 183

(a) The various Rock-Types.
(6) Their Geographical Distribution.
(c) The Rarity of Tuffs and Agglomerates.
V. The Petrography of the Volcanic Rocks ............ 185

(a) The Soda-Rhyolites and Felsites.
(6) The Soda-Trachytes.

(c) The Keratophyres.

(2) The Skomerites.

(e) The Marloesites.

(f) The Mugearites.

(gq) The Olivine-Basalts.

(h) The Olivine-Dolerites.

WEL WhetAssouted Clastie Hocks .......-.ccccscces senses 207
VII. The Chemical and Mineralogical Composition of

ELEU LDA SIS a JRO. -c8 AAs ee 209

VIII. The Sequence in Time of the various Rock-Types. 210

1X. Summary and Coveclusions: ..3...-.....2.....csese0ce0s 211

I. Iyrropuction.

THe region in which this volcanic series is developed occupies an
extensive area in the extreme west of Pembrokeshire on the
southern side of St. Bride’s Bay, and includes the islands of
Midland, Skomer, Grassholm, and the Smalls.

Skomer is by far the largest of the islands, and is situated about
two-thirds of a mile from that part of the mainland which is known
as Wooltack. It has a length, from east to west, of about 2 miles,
a breadth of a little over a mile, and an area of 722 acres.
Between it and the mainland lies the small island of Midland, with
an area of 213 acres, which is separated from Skomer by the Little
Sound, only about 100 yards in width, and from the mainland by
the broader stretch of water known as Jack Sound.

Grassholm Island lies 8 miles to the west of Skomer and covers
an area slightly less than that of Midland, while the Smalls, which
occupy only three-quarters of an acre, lie 8 miles to the west of
Grassholm.

Skomer Island is a detached portion of that plateau which is so
well marked in the west of Pembrokeshire: it rises more or less

1 Communicated by permission of the Director of H.M. Geological Survey.

Q.J.G.8. No. 266. N

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Voal.i67<| THE SKOMER VOLCANIC SERIES, eit

abruptly to an elevation of 200 feet; but, on account of the smaller
size of Grassholm, the highest levels attained by this island fall some
way short of the usual plateau-horizon, while the Smalls rise only
a few feet above the level of high-water at spring-tides. All these
islands, and that portion of the mainland which will here be
described, present a somewhat irregular coast-line, the form of
which may be easily explained after a study of the geological
features. The major indentations are due to differential erosion
controlled by variations in rock-texture and rock-composition ;
while most of the narrow inlets owe their formation to the erosive
action of the sea along planes of weakness determined by steeply-
dipping faults.

The cliffs, as a rule, are fairly steep and give excellent sections,
especially on the northern, western, and eastern sides; but, on
account of the dip of the rocks being at a moderate angle to the
south or south-east, the southern sides of the islands are generally
less precipitous and the cliffs tail off to sea-level in a succession of
dip-slopes.

Skomer Island, in addition to the planing ein it has suffered
in common with the mainland, has had all the remaining depres-
sions filled with loamy sands and gravels of glacial origin, leaving
the solid outcrops projecting, as isolated knolls and ridges, from
almost flat surroundings.

There is little doubt that the Volcanic Series has a more or less
continuous westerly extension from the mainland to some way
beyond the Smalls, for a distinct ridge is indicated on the Admiralty
chart. Moreover, between Grassholm Island aud the Smalls are
numerous rocks, known as the Hats and Barrels, which are just
awash at the low water of spring-tides.

This ridge, however, although it joins all the exposures of the
Volcanic Series, is not parallel to the strike of the rocks, but
probably owes its direction to a system of north-and-south faults,
with westerly downthrows, similar to those observable on the main-
land between Musclewick and Wooltack, which repeatedly displace
the outcrop of the volcanic series northwards.

It can be proved that the volcanic rocks continue toa point some
20 miles to the west of Wooltack, and, on the mainland, they can
be followed eastwards and south- eastwards for 6 miles to the neigh-
bourhood of St. Ishmael’s,' on Milford Haven.

Skomer, Midland, and Grassholm Islands were surveyed during
the year 1908, and the Wooltack promontory in the following year,
when the Smalls rocks were also visited.

II. Previous Lirerarvure.

The previous accounts of the Skomer Volcanic Series are limited
to the writings of quite a few authors, and little of importance was
published until Messrs. Howard & Small undertook a study of the
geology of the island.

1 'T. C. Cantrill, in ‘Summary of Progress for 1909’ Mem. Geol. Sury, 1910,
p. 21.
Wi

178 MR. H. H. THOMAS ON THE [May 1o11,

The following is a list of the chief works and papers which refer
to, or deal solely with, the geology of Skomer Isiand and the
Skomer Volcanic Series, arranged in chronological order :—

1823 [1826]. H.T. Dra Becur. Trans. Geol. Soc. ser. 2, vol. ii, pt. 1, p. 8.

He mentions the ‘trap’ of Marloes and Skomer Island, and states that the
mass consists principally of ‘greenstone,’ but contains rocks intermediate in
character between ‘cornean ’ and ‘greenstone.’ On the map published with his
paper Skomer Island is coloured as consisting entirely of igneous rocks, but it is-
evident that he had noted the sediments which are exposed on the eastern side
of North Haven.

1839. R.I. Murcuison. ‘Silurian System’ pp. 404 & 405.

Refers to the stratified and unstratified ‘trap-rocks’ of Skomer. He makes
the statement that felspar-breccias and conglomerates alternate conformably in
thick parallel masses with regularly stratified purple-green and yellow sandstone
and schist of the ‘Upper Cambrian System.’ Presumably he suggested a
Cambrian age for these rocks, onaceount of their colour and their unfossiliferous
nature.

He evidently thought that some of the Skomer rocks weré intrusive, for he
remarked that ‘the intrusive trap cuts in vertical dykes through the bedded trap
and sandstone.’ This statement, however, cannot be substantiated by reference
to any known section, and it is presumed that he was misled by the isolated
exposures occurring in the interior of Skomer.

Pl. xxxv, fig. 10 gives a somewhat misleading section, and on the map the
Upper Llandovery rocks to the south of Wooltack are lettered as Llandeilo
Flags.

1845 to 1857. Publication of the Geological Survey Map, Old Series, 1 inch to
1 mile, Sheet 40. Surveyed by H. T. De la Beche, A. C. Ramsay, W. T.
Aveline, and J. Rees, Jun. Revised in 1857, with the addition of Silurian
and igneous lines by W. T. Aveline.

In this map all the igneous rocks are coloured as ‘intrusive greenstone,’ and
the sediments of the Skomer Series are lettered as ‘ Llandeilo Flags.’

1867. R. I. Murcurson, ‘ Siluria’ 4th ed. pp. 53, 148.
He here, presumably relying on the work of the geological surveyors, assigned
the igneous rocks to the Llandeilo or Bala Series, but the evidence for this corre-
lation is not given.

1881. EF. Rurtey. Appendix to a paper on the Microscopic Structure of Devi-

trified Rocks from Beddgelert and Snowdon. Q. J. G.S.vol. xxxvii, p. 409.

He gave the first petrological description of any rocks of the Skomer Series,

but unfortunately without any locality other than ‘Skomer Island.’ The four

rocks described by him, which had been collected some time previously by Sir

Andrew Ramsay, were named (1) devitrified banded obsidian, (2) devitrified

banded and spherulitic obsidian, (8) basalt or andesite, and (4) quartz-
oligoclase trachyte (?).

These slides are preserved in the Geological Survey Collections, and corre-
spondingly numbered.

1885. F. Ruttny. ‘Felsitic Lavas of England & Wales’ Mem. Geol. Surv. pp. 18-20..
He here described in greater detail the spherulitic and banded obsidians
already mentioned, his remarks being evidently based on the specimens collected

by Ramsay and preserved in the Jermyn Street Museum.

These rocks can now be referred with certainty to the spherulitic and banded
rhyolite of Tom’s House on the west side of Skomer Island (see p. 187).

1888. J.J. H. Treats. ‘ British Petrography’ pp. 224, 284, & 336.

He described the less acid rocks of Skomer as a ‘magnificent series of basic
lava-flows,’ and referred them mainly to basalts and porphyrites. He noted that
they possess characters of their own, which rendered it difficult to class them
with rocks already described by other authors.

1893. F.T. Howarp & E.W.Smaut. Rep. Brit. Assoc. (Nottingham) p. 766.

‘On some Igneous Rocks of South Pembrokeshire, &c.’
In this is given a preliminary account of the geology of Skomer Island.

Vol. 67.] SKOMER VOLCANIC SERIES. 179

1896. F.T. Howarp & E. W. Smauu. Rep. Brit. Assoc. (Liverpool) p. 797.

‘Geology of Skomer Island.’

The authors give a brief general account of the geology of Skomer Island,
identifying the spherulitic felsite described by Rutley as that exposed at Tom’s
House. They divide the rocks into basalts and porphyrites and felsites, and
give a brief description of the microscopic characters of those types from a few
localities. They detected no fossils in the associated sedimentary rocks, but
regard the volcanic rocks as belonging to the Bala or Llandovery Series.

1896. F.T.Howarp & E.W.Smatt. ‘Geological Notes on Skomer Island’ Trans.
Cardiff Nat. Soc. vol. xxviii, pp. 55-60 & pl. 1.

In this paper the authors published a sketch-map, on a scale of 2 inches to

1 mile, of Skomer, Midland, and part of the mainland, and six drawings of rock-

sections. The rocks illustrated are ‘ basalt’ and ‘felsite,’ the former including

rocks which would now be classed as keratophyres. With the exception of the

illustrations, this paper contains substantially the same material as the British
Association Report for the same year.

1897. F.T. Howarp & E. W.Smaty. ‘Further Notes on Skomer Island’ Trans.
Carditf Nat. Soc. vol. xxix, pp. 62-63.

A short description, with plate, of the section exposed in Pigstone Bay
(Skomer), with additional remarks on other parts of the island. The authors
regard the volcanic rocks of Skomer and the mainland as contemporaneous in
character, and as being of Bala age.

1897. Sir Arcurpatp GEIKIE. ‘Ancient Volcanoes of Great Britain’ vol. i,
p. 207.
Refers to the interesting alternation of basic and acid eruptives, and
summarizes the chief points presented by earlier authors.

1899. E. W. Smaru. ‘A Note on some Skomer Photographs’ Trans. Cardiff Nat.
Soc. vol. xxx, p. 60.
Gives a full-page illustration of the Wick and another of the Mewstone and
Channel, with a brief description.

Undated. E. W. Smart. ‘On the Geology of Skomer & some other Islands of
South Pembrokeshire. A privately printed [1899] but unpublished paper,
4to, 18 pp., with map of Skomer on the scale of 3 inches to 1 mile, and five
other photographic plates of views and micrographs. Two copies of this
work were completed in 1909 by Mr. Small, who, at my suggestion,
deposited one in the Library of the Geological Society, and kindly presented
the other to the Library of the Geological Survey.

This work contains a summary of all the important papers mentioned above,
but presents much fresh material of the nature cf measured sections and
petrographical detail.

The rocks are described as basalts, andesites, and felsites.

III. Tue Srratierapwicat Renations anp Ace or tHe SERIES.

That the Skomer Volcanic Series consists almost entirely of true
laya-flows has been proved by the work of previous observers, and
is clearly demonstrated by the individual thinness of the successive
layers; the vesicular and slaggy upper and lower surfaces; the
frequent occurrence of well-defined fluxion-structures; and the
interlamination of the volcanic rocks with thick masses of sediment
largely made up of the igneous rocks which underlie them.

So far as can be judged, the igneous rocks and sediments have
perfectly conformable relations, although in some instances the
‘former show some signs of contemporaneous erosion. It follows,
therefore, that these sediments must be regarded as forming part

180 MR. H. H. THOMAS ON THE [May 1911,

of the Skomer Volcanic Series; but, owing to their unfossiliferous
nature, due perhaps to the conditions of deposition, they afford no
positive evidence as to the age of the Series as a whole, and for this
we must turn to a consideration of the relations of the Series to the
fossiliferous rocks which bound it on the south and on the north.

On Skomer and the other islands neither the upper nor the lower
limit of the volcanic rocks is reached; but on the mainland at
Wooltack a very complete section reveals the junction of the Upper
Llandovery rocks with the upper portion of the Volcanic Series,
while at Musclewick lower horizons of that Series are seen in
juxtaposition to Llandeilo Flags (p. 182).

We will first consider the relations of the Series to the Upper
Llandovery. The clearest section is that displayed on the northern
side of Renney Shp and in the bay to the north. The rocks dip:
steadily southwards, and as we proceed northwards the cliffs present
a downward succession described in the following paragraphs.

The steep dip-slope, which forms the northern side of Renney Slip,
consists of fairly thick-bedded fossiliferous quartzites and con-
glomerates,' overlain here and there by fossiliferous shales which
have yielded many characteristic Upper Llandovery fossils,* such
as Celospira hemispherica (J. de C. Sow.), Rhynchonella decem-
plicata (J. de C. Sow.), Stropheodonta (Brachyprion) compressa
(J. de C. Sow.), Hncerinurus punctatus (Briinn), and Phacops cf.
stokesi (M.-Edw.).

Below these quartzites comes a basic lava-flow with thin tuffs,.
which occupies the small promontory of the Limpet Rocks. As
this volcanic horizon has been noted at other localities, it has.
proved the most useful datum upon which to base the correlation
of this with other sections. Below the lava-flow comes a series of
grits, some of which are calcareous and have yielded an Upper
Llandovery fauna, a large number of fossils having been collected
from decalcified grits at the base of the cliff in the southern corner
of Anvil Bay. It is thus proved that this lava is of Upper Llan-
dovery age.

These beds pass down into a thick series of unfossiliferous grits
and dark shales, which ultimately comes to rest on a mass of
dolerite. The dolerite occupies Anvil Point, and is regarded as
forming part of the Skomer Volcanic Series.

The complete sequence is represented by the vertical section given
below (fig. 2, No. I, p. 181). On the evidence of this section,.
it would appear that the Skomer Veleanic Series forms the lowest
part of, or is older than, the Upper Llandovery.

Another section (fig. 2, No. IL) on the north, separated from
the first by east-and-west disturbances of considerable magnitude,
is to be seen in the two bays known as Jeffry’s Haven and
Mouse’s Haven. .

1 These quartzites and conglomerates constitute the ‘Tentaculite Grit’ of

earlier writers.
’ Identified by Prof. O. T. Jones, and preserved in the Geological Survey

collections.

Vol. 67.] SKOMER VOLCANIC SERIES. 181

Jeffry’s Haven shows Upper Llandovery shales resting upon
quartzites and shales, and followed downwards by the basic lava
which here takes on a good pillow-structure. Below the lava are
more quartzites about 50 feet in thickness, which rest directly upon
typical sediments and volcanic rocks of the Skomer Series. Although
there are some signs of movement between the Skomer Series and
the overlying Llandovery rocks, it seems unlikely that any beds
have been removed from the sequence.

Taking the Llandovery volcanic horizon as a datum (see fig. 2),

Fig. 2.
Non te Nos fr
ANVIL Bay. JEEFFRY’S HAVEN,

U Upper Llandovery
Upper SRS, eee t Upy :
Stralens s#.c ceo oss a § Shales.
oo i Quartzite.
[o_o ooo]
3
Conglomerate ......... Quartzite and shales
with Lingula.
i ee
ae Bae eceah asnnasaeene i Pillar clacs:
LL eee wr Be
SBIEB! soscscoecr eee ee } Quartzite and con:
QuARtzte® cvececcie j glomerate.
1 Basalt of Skomer:
Shales with Stropheo- { : ae

w Series.
donta, Proetus, ete.

Conglomerate ......... {

Grey shales with
quartzites ............

[Vertical scale :
/ 1 centimetre =—50 feet ;
or 1 inch =125 feet. ]

Massive conglome- 4 fe 9 © © 9

EAGGT clot eee 1 [8 oo Ss
) 2 oo of

EGS CLAY | crasereaesn tee \

Dolerite of eye i

o> ic |
Series! (isdsieie ee

and comparing the thickness of Llandovery sediments represented
below it in the two sections, we at once notice a great disparity ;
for, whereas there are at least 250 feet of beds between it and the
Skomer Series in the Renney Slip and Anvil Bay scction, there are,
at the most, only 50 feet of beds in the Jeffry’s and Mouse’s Haven
section. This would point to an overlap within the Upper Llan-
dovery and an overstep of the Upper Llandovery on to the Skomer
Series. Therefore, despite apparent concordance in dip and strike,
I am inclined to the conclusion that the Upper Llandovery
rests unconformably upon the Skomer Series, and that
the volcanic rocks are thus of pre-Upper Llandovery

age.

182 MR. H, H. THOMASON THE [May ro11,

Unfortunately, this is the only direct evidence as to the age of
the series that it is possible to bring forward; but much important
information which bears indirectly upon this subject can be gathered
from other districts in the west of Pembrokeshire.

At Musclewick, a little over a mile to the east of the map, near
the village of Marloes, the lower limit of the Skomer Series is
reached. Concerning this, Mr. T. C. Cantrill has kindly furnished
the following account :—

‘The lower limit of the Skomer Series is revealed between St. Ishmaels and
Marloes. A rhyolite, which here forms the lowest exposed member of the
Volcanic Series, is everywhere bordered on its northern or lower margin by an
outcrop of Llandeilo Flags from which it dips away without obvious discord-
ance. At first sight, therefore, it would appear as if the igneous series was
newer than, and immediately succeeded, the Llandeilo Flags, and might there-
fore be referable either to that formation or to some part of the Bala or Lower
Llandovery Series. Further examination, however, of the section exposed in
Musclewick Bay proves that there the junction of the volcanic rocks with the
Llaudeilo is a faulted one; but, unfortunately, the fault is vertical, and the
direction of movement remains uncertain. ‘This section, therefore, still renders
it possible for the igneous rocks to be newer than the Llandeilo Flags, against
which they are faulted ; but general considerations make it probable that the
whole length of junction is a fault, along which the volcanic rocks as older beds
have been thrust from the south on to the newer Llandeilo Flags.’

It appears, therefore, that while pre-Upper Llandovery in age
they may be even pre-Llandeilo. ‘This suggestion is borne out bya
consideration of the sequence of Lower Paleozoic rocks exhibited
in the neighbourhood of Haverfordwest, about 10 miles away. In
that district there is practically an unbroken succession from the
Upper Llandovery to well down in the Arenig Series, and in this
sequence there is no indication of any marked period of vulcanicity,
neither is there any stratigraphical break of sufficient magnitude to
mark the eruption of some 3000 feet of volcanic rock in an area so
close at hand and along the same line of strike. Of course, we are
aware that both the beginning and the close of the Didymograptus-
murchisont Zone and the upper limit of the Llandeilo Series were
horizons of volcanic activity in other districts; butin South Wales,
south of the pre-Cambrian ridges of St. David’s and Hayscastle, these
horizons are marked only by thin ashes, which show no tendency to
greater development in a westerly direction.

In the Didymograptus-extensus Zone, however, we meet with
evidence of prolonged volcanic activity, as indicated by the great
thickness of acid and intermediate lavas at Trefgarn,' north of
Haverfordwest. The Trefgarn Volcanic Series, in the composition
of its members, presents many characters in common with those of
the Skomer Series, and the rocks evidently belong to the same
petrological province, although not showing the variety of the
Skomer Series.

1 The age of these rocks has lately been established by the discovery of an
_Arenig graptolite-fauna in shales associated with the volcanic rocks in Trefgarn
gorge. See ‘Geology of the Country around Haverfordwest’ Mem. Geol. Surv.
(in the press).

mroll."6'7. | SKOMER VOLCANIC SERIES. 183

Below the Hxtensus Zone, from the Nesuretus Beds of Hicks to the
base of the Cambrian, there seems no place for a volcanic series of
such magnitude; nor in the pre-Cambrian rocks of St. David’s or of
the Hayscastle! district are there any rocks that have much in
common with those of the Skomer Series. Such as the evidence is,
therefore, it seems to point to the series being of Arenig age and
on the same horizon as the rocks of Trefgarn, and of Llangynog
in Carmarthenshire,’ that is to say, probably rather low down in
the Didymograptus-extensus Zone.

IV. Tae Votcanic Rocks.

The igneous rocks of the Skomer Series as developed on Skomer
Island, where the greatest thickness can be studied, consist almost
entirely of groups of lava-flows of varying composition, unaccom-
panied by dyke-rocks of any description, and penetrated only by a
few basic sills.

The subaérial character of the flows seems to be proved by
the frequent occurrence of beds of red clay; by the red staining
of many of the scoriaceous and highly vesicular surfaces; by the
conglomeratic layers at the top of certain flows; and also by the
character of the associated coarse sediments.

The thickness of rock exposed on Skomer exceeds 2900 feet, and
even then neither the base nor the summit of the Series is reached :
all this is built up of flows which seldom attain 10 feet in thick-
ness, and are often thinner, except in the case of the more acid
rocks.°

That the eruptions were of the fissure-type is suggested by the
general absence of pyroclastic rocks, and by the great lateral extent
of individual flows compared with their thickness. The vents lay
probably to the west of Skomer, as is indicated by the thinning
of the series and the more rapid alternation of types in an easterly
direction. Most of the rhyolites and the dolerites seem to thin out
eastwards, and whole groups represented on Skomer are missing on
the mainland.

(a) The various Rock-Types.

The rock-types previously said to be represented in the Skomer
Series are the basalts, andesites, porphyrites, felsites, and devitrified
obsidians of Rutley, Teall, and Howard & Small.

Through the kindness of Messrs. Howard & Small I have been
enabled to work at the large number of rock-slices which they had
had made, and in addition have studied scme 250 slices of rocks
collected during the recent survey. It has thus proved possible to
separate the rocks according to eight distinct types, for two of

1 These rocks have lately been mapped by Prof. O. T. Jones and myself.
2 T. C. Cantrill & H. H. Thomas, Q. J. G. S. vol. Ixii (1906) p. 228.
> J.J. H. Teall, ‘ British Petrography’ 1888, p. 224.

184 MR. H. H, THOMAS ON THE [May rorr,

which it has been thought advisable to take the names skomerite
and marloesite. |

The main rock-types which have been mapped are the following :-—
soda-rhyolite and felsite, albite-trachyte, keratophyre, skomerite,
marloesite, mugearite, olivine-basalt, and olivine-dolerite.

The acid rocks are easily separated in the field from those of
more basic character; but further subdivision on the ground 1s
difficult, on account of the fine texture of the lavas. Generally
speaking, however, the olivine-basalts can be detected by their
darker colour, finely crystalline character, and by having a purple
tinge imparted to them by the augite.

It has not been possible to separate in the field the trachytes,
keratophyres, skomerites, and marloesites one from the other, except
in a few instances. As a whole, however, these rocks may be
separated from the rhyolites on the one hand, and the mugearites
and basalts on the other, by their greenish or greenish-grey colour
and more vesicular nature.

(6) Their Geographical Distribution.

The geographical distribution of the Skomer Volcanic Series as a
whole has, for the most part, been clearly indicated by previous
writers.

The rocks near St. Ishmael’s, however, were regarded as intrusive,
and were shown on the old edition of the Geological Survey Map
(O.S. Sheet 40) as crossing the strike of the sedimentary rocks
with which they are associated. Mr. Cantrill* has clearly demon-
strated their true character, and described their extent.

In detail, the members of the Skomer Series have a simple dis-
tribution. The islands of the Smalls and Grassholm are too remote
to allow of a detailed correlation with Skomer and the mainland ;
but Skomer, Midland, and the mainland are directly comparable.

A most useful datum, in addition to that of the sedimentary
group, is furnished by a band of red felsitic rock which occurs just
south of the Wick on Skomer Island, and lies 250 feet above the
sediments. It may be detected on the Neck and on Midland
Island, where, on account of its superior hardness and splintery
fracture, if makes conspicuous crags.

The subdivisions as developed on Skomer may be found to a
limited degree on the mainland ; but the rocks are evidently thinning
in an easterly direction, and some of the minor divisions have
disappeared. The rhyolite of Musclewick (east of the map) might
well be on the horizon of that of the North Cliff of Skomer. It is
presumably succeeded by the mugearitic group of Wooltack, which
may represent that of the centre of Skomer: the lower basalts of
Skomer being unrepresented on the mainland. The keratophyres,
etc., below the main mass of sediments, and the basalts above the
sediments, are present in both areas. Minor differences between

1 ‘Summary of Progress for 1909’ Mem. Geol. Surv. 1910, p. 21.

Vol. 67.] SKOMER VOLCANIC SERIES. 185

the various districts would be expected, but in general the agree-
ment is fairly close.

With regard to the mode of occurrence and distribution of the
rock-types, I have little to add to what has been admirably put
forward by Messrs. Howard & Small and to what may be gathered
from a study of the appended map (PI. XI).

(c) The Rarity of Tufts and Agglomerates.

As is far from unusual in a volcanic series of this nature, pyro-
clastic rocks are of exceptional occurrence,' and, when they do
occur, they are chiefly associated with the more siliceous rocks. On
Skomer Island a thin series of rhyolitic tuffs, well bedded and
reaching 8 feet in thickness, underlies the trachyte of Pigstone
Bay, but is not present on the eastern side of the island.

A zone of rhyolitic breccia in the north-east of Skomer, called
by Mr. Small (1899-1909) the Waybench Breccias, is presumably
on the horizon of the rhyolite of the Table (op. ct. p. 10) and
represents the breaking up of the flows in an easterly direction.
Similar brecciation is noticed in the pink felsitic rock on the Neck.
and Midland Island (below). ‘There is almost complete absence ot
any tuffs of intermediate character; but traces may be observed,
on the surfaces of many flows, in the form of highly siliceous flinty
patches of clastic material occupying small hollows in the lava-
surfaces. Such patches may be studied in Welsh Way and on the
Neck. Sections indicate that the ash has undergone much silicifi-
cation. On the mainland a thin series of tuffs may be seen in the
cliffs on the north side of Cable Bay, below the quartzites.

V. Tun Perrocrapuy oF THE Votcanic Rocks.
(a) The Soda-Rhyolites and Felsites.

The rhyolitic rocks of Skomer and the mainland are, for the most
part, pale as regards colour, varying from white to cream; but: occa-
sionally they have a distinct violet tinge, such as is observable in the
flows which form the halt-tide rocks between the Garland Stone and
the North Cliff of Skomer. The rocks of the North Cliff are often
beautifully banded, but seldom spherulitic; those of Manies Island
are both spherulitic and vesicular.

The flows of Tom’s House and the Basin are spherulitic and
banded rhyolites, of which the altered spherulites attain considerable
size. Therock at the Table is thin and composed of three bands,
a white band between two of darker hue. To the south towards
the Spit the light band appears to split into three, its central portion
being darker. Part of this series was considered by Mr. Small to
exhibit pyroclastic characters (1899-1909, p. 5).

The red rock of the Wick, Kittiwake Cave, the Neck, and Midland

' A. Harker, ‘Tertiary Igneous Rocks of Skye’ Mem. Geol. Surv. 1904,
p: Gr

186 MR. H. H. THOMAS ON THE [May rog1t,

Island is also a thin mass, and in the hand-specimen shows no
structure other than occasional flow-brecciation.

The Mewstone mass may be intrusive; it succeeds a series of
quartzites, and its base is more glassy (fig. 8A, below) than its
higher portions. It is about 100 feet thick, and shows a roughly
columnar structure towards the summit of the Mewstone.

The rhyolitic rocks of Musclewick on the mainland are similar
to those of the North Cliff of Skomer, and are probably on the same
voleanic horizon. Microscopically, the rocks range from crypto-
crystalline devitrified obsidians to almost holocrystalline varieties
presenting microlitie or even trachytic structures. The devitrified
obsidians, such as those forming the base of the Mewstone and
some bands in the northernmost mass, are beautifully perlitic
(fig. 3A), and occasionally, like some of the Tom’s-House rocks,

A=Perlitic structure in the lowest part of the soda-rhyolite (?) of the Mewstone
(Skomer). Slide H 7116.1 x 25 diameters.

B=Contorted lines of flow in the soda-rhyolite of Bull Hole (Skomer) ; from
a slide kindly lent by Mr. F. T. Howard. xX 25 diameters.

both perlitic and spherulitic. Flow-structures are almost constant
features, and contortion of the flow-lines may be noticed both on
the macroscopic and on the microscopic scale (fig. 3B). On a large
scale, these contortions are well exhibited above Tom’s House.

1 Where registration-numbers of slides are mentioned, these refer to the
slides in the collections of the Geological Survey.

Vol. 67.] SKOMER VOLCANIC SERIES, 187

In the finely banded rocks, like those of the Basin, the bands are
often not more than a millimetre in width, and appear as alternating
light and dark layers. The light bands consist either of quartz,
often with slender needles of apatite projecting inwards from the
sides of the band, or of patches of alkaline felspar or coalesced
spherules. The darker bands are composed of iron-stained erypto-
crystalline felsitic material, almost isotropic, but with small patches
of secondary felspar which appears to represent spherulites.

The coarsely spherulitic rocks of Skomer have received a fair
share of attention since they were first described by Rutley in
1885, and are by far the best-known members of the Skomer

Fig. 4.—Nodular rhyolite of the Basin, Skomer Island.

Series. They are magnificently displayed on the coast between
Tom’s House and the Basin. The smaller spherules, those about
the size of a pea or less, have a concentric structure towards the
exterior, but the internal structure is fibrous andradiate. ‘There is
seldom any recognizable nucleus, and the felspar fibres radiate
either from a central point or from a short line. The felspar has
optically negative elongation, practically straight extinction, and
low refractive indices.

The spherules are usually white or grey, and are often collected
in bands to form large axiolites, while a mammillated or botryoidal
structure is sometimes observable on their surfaces. The big
spherules are mostly solid spherulites, and are generally paler than
the rock in which they lie. They range up to 9 or 10 inches in

188 MR. H. H. THOMAS ON THE [ May rg1I,

diameter, and are distributed more irregularly than those of smaller
size. ‘They vary from perfect spheres to elliptical and disc-like
masses flattened parallel to the flow-banding. ‘Their surfaces are
often ribbed or ridged parallel to the lines of flow, which may be
traced across any internal structures. In cross-section they have
a marked concentric (as well as radiate) structure; but there is
evidence in many instances of hollow spaces, either concentric or
more often central, whicb have been filled up with dark siliceous
matter or secondary felspar. It has been argued that these hollow
spaces were original, and that the structures are lithophysal. The
proof of their secondary origin, however, lies in the fact that spheru-
lites are seen which are composed of two parts—an outer felspathic

A=Pseudomorph after augite in secondary quartz and chlorite, in a purplish
soda-rhyolite. Base of the North Cliff opposite the Garland Stone
(Skomer). Slide E 7763. x 100 diameters.

‘B=Pseudomorph after augite in chlorite, in the soda-rhyolite (?) of the Mew-
stone summit (Skomer); from a slide kindly lent by Mr. F. T. Howard
xX 85 diameters.

layer, and an inner chalcedonic central portion. The outer layer is
radiate, but the needles, if produced, would meet at the centre of
the chalcedonic mass. ‘The chalcedonic material radiates inwards
from a series of points on the surface which separates the fel-
spathic and chalcedonic portions of the spherulite. This clearly
points to the removal of the central part of the original felspathic
spherulite and its replacement by chalcedony. Some spherules
contain a nucleus of cryptocrystalline silica or flint; and, in fact,
Mr. Harker’s description of the nodules in the Carnarvonshire

Vol. 67.| SKOMER VOLCANIC SERIES. 189
rhyolites' might have been written for those of Skomer, with
which he himself compares them. I agree with him in regarding
these nodules, now often devoid of structure, as having been derived
from simple spherulites by a process of alteration and substitution.

Phenocrysts are never present in large numbers in these rhyolitic
rocks, and are often entirely wanting. When present they consist
either of minute crystals of an acid plagioclase-felspar (between albite
and oligoclase), or of microperthitic intergrowths. No potash-felspar
has been detected, although the analysis of a rock from the Table
(Analysis I, below) shows that potash is present in small quantity ;
it probably exists, therefore, in the groundmass, in the perthite, or
in the phenocrysts in the albite-molecule, which may contain potash
up to 16 per cent. of the total alkalies.

The albite-oligoclase crystals are usually twinned according to
the Carlsbad and albite laws, but pericline lamelle are rarely seen.
Occasionally these rocks contain scarce and small chloritic and
serpentinous pseudomorphs after some ferromagnesian mineral,
such as those in the rocks of Manies Island and the island south-
west of the Garland Stone, which appear to be after biotite; and
those in the uppermost portion of the Mewstone mass, which
appear to have the form of augite (fig. 5 B, p. 188). Sometimes,
in rocks which have undergone secondary silicification, a mosaic
of secondary quartz and chlorite occupies the cavity left by the
decaying mineral (fig. 5 A, p. 188).

The groundmass of the devitrified obsidians is usually crypto-
crystalline felsitic material, but in the more felspathic varieties it
breaks up into irregular ill-defined patches of felspar, representing a
type of devitrification common to many of the older rhyolitic lavas.

Ae LE, IDE:
SiQs. eepeeose syns 79°64 778 77:29
TOg Sve eensehe ss 0°50 igh a
AlO}g operon oe! 11°44 13:2 14°62
1 0 Allene se ea O11 0-2 trace
HeQ pe aeeesecnacn ates 0-30 O07 sap
Mn Oye — 0-08
CaO) Seeeeee eeeccecss O71 trace i:
MeOee tie a... 0-15 trace 0°38
KEO!. 208. eee 0°38 271 O16
Na: Oigee ee essa, 6°40 od 7 60
HO abi@neG.....°.. 0-16 ten or
H,,O above 105° C... 0-30
PQs eee ee 0:08
OOS 5 Beet es ses 0-02 ba a3
Loss on ignition ... ae 0°6 O'd57
Potala? 2a Gecez0e- 100°27 Say 100-62
Anal Weds: 2 « E. G. Radley. F.H. Hatch. F. H. Hatch.

I=Soda-rhyolite, near the Table, top of cliff, east of the Spit (Skomer).
[Anal. No. 345, Slide E 7768. ]
I1=Soda-felsite, south-east of cairn on Castletimon Hill, Co. Wicklow (Lre-
land). Geol. Mag. 1889, p. 546.
III =Soda-felsite, Brittas Bridge, Co. Wicklow (Ireland). hid. p. 72.

1 « Bala Volcanic Series of Carnarvonshire’ 1889, pp. 29 e/ segg.

190 MR. H. H. THOMAS ON THE [May 1911,

The accessory minerals are zircon, apatite, titaniferous iron-ore,
magnetite, and pyrite, while common secondary minerals are
granular sphene and chlorite. In some rocks (as, for instance, the
Table felsite) the sphene is intensely pleochroic, like that of some
metamorphic rocks, and has a almost colourless, § pale greenish,
and ¢ deep reddish with 2 HE about 63°. The chlorite is distributed
through the base of the rocks, partly replacing felspars and in-
filling occasional vesicles.

All these rhyolitic rocks are evidently rich in silica and soda,
and the analysis set forth on p. 189, of a rock forming a white and
little altered band above the Table, is representative of the class.
The analysis is of a rock which evidently consists almost entirely of
quartz and albite; for its theoretical percentage composition would
be orthoclase 2°2, albite 53°9, anorthite 1-1, and quartz 27°6.
These rocks are closely allied to the soda-felsites of the South-East
of Ireland, described by Dr. Hatch,’ of which two analyses are
tabulated for comparison. In the nomenclature of the American
classification this rock would be designated westphalose, and
placed in the persodi¢ division of alaskase, a division containing
the quartz-keratophyres of some authors.

The soda-rhyolites, with the assumption of a trachytic micro-
scopic structure and an increased percentage of combined or free
orthoclase, pass gradually into the albite-oligoclase trachytes
described below.

(6) The Soda-Trachytes.
These rocks may be divided into three types :—

(1) Soda-trachyte, with little or no augite or hypersthene (for instance,
Slides E 7029, 7122).

(2) Olivine-soda trachyte, with pseudomorphs after olivine (for instance,
Slide E 7759).

(3) Hypersthene-soda trachyte, with pseudomorphs after hypersthene (for
instance, Slide E 7148).

The first type is common and well represented on Skomer in the
central belt of trachytic lavas which form a clearly-marked band
across the island. The olivine-bearing rocks are best seen on
Skomer and in the cliffs to the east of Martin’s Haven.

The hypersthene-bearing type 1s represented on the mainland at
Crabhall, north ef Dale, where a large quarry has been opened for
road-metal. In the hand-specimen all these rocks are somewhat
splintery, grey in colour, and it is but exceptionally that they
show any marked vesicular habit (for instance, Slide K 7485). They
have only a few phenocrysts of sufficient size to be distinguished
by the unaided eye. These rocks weather with a pale buff-coloured
crust, which may extend for about half a centimetre into the rock.

Under the microscope they are seen to consist of a few well-formed
phenocrysts of albite, usually twinned, set in a mass of microlites of
similar composition. The structure is typically trachytic.

1 Geol. Mag. dec. iii, vol. vi (1889) pp. 70 & 545.

Vol. 67.] SKOMER VOLCANIC SERIES. 191

The phenocrysts in the finer-grained varieties (fig. 6, B, below)
reach 2 mm. in length by about 0°7 in width, but the majority
are smaller. ‘The microlites in the same rock measure about | mm.
in length by ‘Ol mm. in width; they are arranged in well-
defined flow-lines, and enclose between them minute specks of
chlorite and grains of iron-ore. In these rocks the rare vesicles
(for instance, E 7029, 7285) are filled with a mosaic of quartz,
and lined with a little chlorite; while the groundmass contains
; omg granules of secondary sphene. In the rock figured below
(fig. 6, “A) the microlites are somewhat larger than usual, but the

Fig. 6.
e A
Nh Vs; WHE YEU Ty 1
Ge uy ne Wey La} in Ha)
Gat Ss %y ly sD

oi) rs Gs Mp Ly Wap
We iil fri eal Vi Yi; Listy

a Wha AGE Lipsy, YY GZ YP)

a! Mn Vee ie LAG)

YL} GE

Zaye
,

ANE Li
Qs

\t i
Onis S Le 4 107 ys a 0] fi

iy, ys ae We AS
7 Pts

i yy AN fi

Hi A Sey 4
\ i Yee SN |
ee ‘ SH pe
SSN ih i cue is
ail il itis Ai ue Wh yy, _S ii
% j Ne a tn Ve oe oe sone Co, lly? i ay
\ ~ Ni ua oa S oo ye i, Wy Hl 4 iy
Gn RS Wis SSNS f il Ns iN he eg iy / ay
aya Ft a Wit ve ny I He i J Ly WOK yf i
‘ wy Cal Ally ee ae i if NG My
ine Silly TY? ai HAL ie Hi AY LY
: ea ui fe cS ay?

A=Albite-trachyte from Captain Kite’s Rock ee Slide E 7029, ordinary
light. x 25 diameters.

B=Albite-trachyte, from low down on the North Cliff of Skomer, opposite
the Garland Stone. Slide E7122, ordinary light. X 25 diameters.

[Both these rocks show small Bree: ysts of acid plagioclase-felspar set in
a fine massof acid plagioclase-microlites. The rock A shows well-shaped
apatite-prisms. |

flow-structure is still beautifully preserved. Occasionally, as in
this rock (EK 7029), there occur small though undoubted pseudo-
morphs after augite ; but the percentage of ferromagnesian mineral
is always small. Apatite is not an uncommon accessory (fig. 6, A)
and the iron-ore is titaniferous. These soda-trachytes show a
family connexion with the keratophyres, in the restricted sense—
into which they would pass by an increase in the size and basicity

Q.J..G. 8. Nop266. 0

-_~-

192 MR. H. H. THOMAS ON THE [May rort,

of the felspars, by the less complete development of flow-structure,
and by assuming a more vesicular character,

The olivine-bearing rocks show in the presence of olivine their
family resemblance to the marloesites (p. 198). They contain but
little fresh granular augite, sometimes none; clivine, however, may
be represented by pseudomorphs of considerable size (fig. 7, B,p. 193)
in serpentine or chlorite. The ground-mass has a fine felsitic
or trachytic character, and is composed of minute albite-oligoclase
laths exhibiting a felted or fluidal arrangement. The felspar
phenocrysts are albite or albite-oligoclase. In common with the
marloesites (which see), these rocks often contain minute crystals

TV; Vi. Wal:
SIE Oho ee eee 58°47 61:01 55°38
AO 5 teenies eee 2°17 0-45 0:90
AW 5 Peart wees 18°60 18°45 18°34
Be O vurcdecent eee nee 1-92 2:09 1:13
HeO“aceseen sence coer ATL 0:80 5°86
Vin ©». (2) Sogennee erect 0°19 trace awe
Ba). Rut ieee tact 0:04 the n, d.
CaO) etcetera 0-99 fou 3°25
MgO. ieseencacee 0°94 0-94 OAT
Katy Boe penestcsece 3°30 4°75 0:22
NacO? wae... 5°52 7°33 712
iSO oe ee aetenn trace Re n.d.
FeO abtO5eCs 2.4. 0-50 } 3-09 0°48
H,O above 105° C.... 2°19 2°39
BOP a ese ecer cea nart ss 0:45 trace
| RRs eee 0:04 2:00

CU eric de eho de 0:02 n.d
Motalsig ict cct 100°11: 100°82 100°54

PAUTCD IE Hie Ne ccc en8 E. G. Radley. Deicke. J. V. Elsden.

IV=Soda-trachyte (lava), North Cliff of Skomer, opposite the Garland Stone
[ Anal. No. 347, E 7769], same rock as E 7122.

V=Soda-trachyte? (block in tuff), Dachberg, Rhéngebirge. H. S.

Washington [after F. Rinne], Prof. Paper 14, U.S. Geol. Surv. 1903,

pp. 396-97.

VI=‘ Lime-bostonite.’? Abercastle (North Pembrokeshire). J. V. Elsden,
Q. J.G.S. vol. lxi (1906) p. 596.

and grains of a brown hornblende, similar to that detected by
Mr. Harker! in the mugearites of Skye.

The hypersthene-bearing rocks (fig. 7, A, p. 193), or the Crabhall
type* of soda-trachyte, have a ground-mass like that already de-
scribed ; but it differs in the inclusion of fairly large, stained, and
striated prisms of apatite, and in the complete absence of granular
augite. The bastite-pseudomorphs after the rhombic pyroxene
measure up to 2 mm. in length, and the porphyritic albite-oligoclase
felspars up to 8 mm. ‘Lhe bastite is surrounded by an opaque

1 ‘Tertiary Igneous Rocks of Skye’ Mem. Geol. Surv. 1904, p- 262.
2 J.J. H. Teall, ‘ British Petrography ’ 1888, p. 284 [‘a somewhat basic por-
phyrite oecurs at Crab Hole near Dale’],

Vol. 67. ] SKOMER VOLCANIC SERIES. 193

border of iron-ores, and often includes granules of brown sphene
(fig. 7, A, below), A certain amount of quartz in the ground-mass
aud also enclosing felspar-microlites appears to be original,

The fine-grained trachytic rock from the North Cliff of Skomer
{andesite of Howard & Small) has been analysed (sce Analysis LV,
p. 192), and by its high percentage of alkalies evidently takes its
place among the trachytes. The high percentage of potash was
rather surprising, for, as in the case of the rhyolites, no orthoclase
could be detected. The analysis would, however, suggest the
presence of 19 per cent. of orthoclase, 46 per cent. of albite, and
© per cent. of anorthite. Chemically, the rock compares fairly well

= iP

: &
Cop

Atl . 9 S (oe) ee
a) Les: NRE GR A AZ
ON AY Le ~\ ST Wad ste Lh orth,

AV

-

’ Le
i 3 ous E } i >
: ze EAA 7 NRL Wace
DEL ss M6 ZN 44 Is \ey fess
we IZ.

S
E IW }
ANN A
YN INV EL Zor
vaa2 if se
327

A= Albite-trachyte, with pseudomorphs after a rhombic pyroxene ; from Crab
Hall Quarry, north of Dale. Slide E 7148, ordinary light. x25 diameters.

B=Albite-trachyte, with pseudomorph after clivine. Cliff east of High Point,
Marloes. Slide E 7759, ordinary light. x 25 diameters.

with a soda-trachyte (Analysis V, p. 192) from the Rhongebirge
described by Prof. Rinne; but it differs considerably from the
keratophyres, as represented by Dr. Elsden’s ‘ lime-bostonite’ (Ana-
lysis VI, p. 192).

(c) The Keratophyres.

If the term keratophyre were used in the sense in which
Prof. Rosenbusch uses it, all the rocks so far described would have
been included thereunder ; but it seems undesirable to include rocks
which have always been regarded as rhyolites, and rocks which

02

194 MR. H. H, THOMAS ON THE [May ro1tr,

present undoubted trachytic affinities despite the excess of soda
over potash. Moreover, these more acid rocks are readily dis-
tinguished in the field from more basic lavas, which must be re-
ferred to as keratophyres. In this paper, therefore, the term
keratophyre is restricted to those soda-rich lavas which would
fall between the soda-rhyolites and the spilites, and differ chemically
as well as structurally from the rocks hitherto described.

They are strongly represented on Skomer Island and the main-
land, and are identical in most respects with the ‘ lime-bostonites ’
of Dr. Elsden,’ which Prof. Rosenbusch *? places with the kerato-
phyres. In the case of Skomer the name ‘ lime-bostonite’ seems

perme

‘e

>
. iC =
ee, 4 =! ~N
De Sy < -
- *
Vossen IS
aoiae SNe ; so,
ecg ee - \e :
~~ S Se HAGA \ NOC
Sa St es ft ves gee Oe
ages ffs QY gue hee)
- a

ea)
a
US NSS ENE
So Ze aR sean i
. ta — “So
. Se: ie —:
eS

ow

f bs \ ba

He ee eo ‘
| gem. emcee, 5
Vif, GAZ Ge

ee <a

= He ‘ %
NR ORS FNP:

ae

ue vise

. es 4 EES
aL Sale Us
WAD

NG
tL, ‘ig

A= Keratophyre with albite phenocryst and chlorite-filled vesicle. Above the
soda-trachyte of North Castle (Skomer). Slide EH 7024. x 25 diameters.
B=Keratophyre, non-porphyritic and non-yesicular. Below the soda-rhyolite

of Bull Hole (Skomer). Slide E7128. x 25 diameters.

unsuitable, for the rocks are certainly not intrusive like the similar
rocks in North Pembrokeshire; nor is their structure that which is
met with in typical bostonites.

As represented on Skomer and the adjoining mainland, they are
fairly compact, grey to buff-coloured, somewhat speckled rocks, with

1 Q. J. G. 8. vol. Ixi (1905) p. 594. I am indebted to Dr. Elsden for kindly
placing at my disposal his type-sections of rocks from the Abercastle district
of North Pembrokeshire.

2 ‘Mikroskop. Physiogr. d. Mineralien & Gesteine’ 4th ed. vol. ii, pt. 2 (1908),
p. 944. See also his ‘ Elemente der Gesteinslehre’ 3rd ed. (1910) pp. 345-46.

‘Vol. 67.] SKOMER VOLCANIC SERIES. 195

conspicuous vesicles which are usually drawn out slightly in the
direction of flow. These lavas were the most viscous of all but
the rhyolitic rocks, and evidence of explosive outbursts may be
gathered from the small patches of silicified pyroclastic material
(for instance, E 7050) occupying hollows in the surfaces of the
lavas (p. 185).

Porphyritic crystals of acid plagioclase are sometimes present,
but seldom reach any considerable size. The ground-mass, as in
the case of the trachytes, consists of lath-shaped microlites of
albite-oligoclase felspars. ‘The laths are usually well bounded, but
in some cases they are somewhat indefinite, both as to their lateral
boundaries and as to their terminations. ‘They are usually twinned,
sometimes only once, but more often if their breadth will allow of
it. Flow-structures are not well shown, the structure being best
described as ‘ felted.’ The vesicles, which are numerous and large,
are usually filled with chlorite, which may be either the ordinary
feebly birefringent variety or the highly birefringent minerals
allied to delessite. In both cases the material filling the cavity
has a radiate structure. Occasionally the vesicles may be filled
with secondary quartz (EH 7111); but this is unusual, and probably
represents surface-silicification. Granules of secondary sphene are
abundant, and often good crystals project from the rock into the
-vesicular cavities.

Tron-ores in general are less common than in the soda-trachytes,
but the felspars are often deeply iron-stained.

The felspar phenocrysts are albite-oligoclase, but are slightly more
basic than those of the trachytes. Some appear to be microper-
thitic, and exhibit a curious vermicular structure, due presumably
to the alteration or absorption of one constituent, They have, in
most cases, suffered a fair amount of decomposition, giving rise to
patches of calcite and less frequently epidote. Original ferro-
magnesia minerals are very rare, and almost always absent from
‘these rocks.

The interstices between the microlites are filled with chlorite
and a little cryptocrystalline material which might represent
residual glass. Generally speaking, chlorite is not very plentiful in
the ground-mass, but it may become a prominent constituent, and
the same remark applies to the dusty iron-ores (E 7047).

In composition these rocks are evidently allied to the soda-
trachytes, but differ chiefly in containing a greater amount of
-chloritic material and granular sphene, and structurally in the
absence of well-defined fluxion-phenomena. ‘They are so similar in
mineralogical character and structure to Dr. Elsden’s lime-bostonites
that it was thought unnecessary to analyse them specially. Their
composition will be approximately represented by the analysis of
the Abercastle rock, tabulated on p. 192 (Analysis VI). It will be
seen by comparing Analyses IV & VI that they are slightly more
basic than the soda-trachytes and richer in lime and magnesia, but
that the total alkalies approximate in value.

196 MR. H. H. THOMAS ON THE [May rort,.

(7) The Skomerites.

A very prevalent rock-type on Skomer and the mainland is, as far~
as | am aware, peculiar to the district, and the name skomerite.
has therefore been applied to it.' The skomerites are compact,
fine-grained, dark-grey rocks, with atinge of green. They have a
finely crystalline appearance, and show minute laths of felspar to.
the naked eye. They weather with a pale crust to a few milli-
metres in thickness, and are not so highly vesicular as the kerato-
phyres.

Specimens collected from a flow beneath the Mewstone quartzites -
(E 7056) and from above the soda-trachyte of Pigstone Bay (KE 7090) .
may be regarded as typical. These rocks consist of augite, olivine,
albite-oligoclase felspars, accessory iron-ores, and secondary chlorite’
presumably replacing a fine-grained or glassy base.

The augite is a greenish variety, and makes a fifth to a quarter of
the rock. It occasionally occurs in clots, but usually is evenly
distributed as subidiomorphic crystals, grains, and subophitic-
patches, ranging up to 10 mm. in greatest dimension, but generally
much smaller (fig. 9, A, p. 197). There are seldom more than two
of the larger crystals in the area of any slide.

The subidiomorphic crystals and granules appear to belong
to the same period of generation, and there was evidently but a
very small time-interval between the consolidation of the various -
constituents. A few of the larger augites show slight resorption-
borders, and many of the crystals are twinned, a feature which.
contrasts them with the augites of the olivine-basalts (p. 204).

Olivine is not an abundant constituent, but is usually present
building small idiomorphic crystals about 0-3 mm. in length, .
pseudomorphous in dark green serpentine or strongly birefringent
chlorite or iddingsite (?).

The porphyritic felspars are much decomposed and replaced by
chlorite. They are generally not very well formed, and have-
their angles somewhat rounded. Their refractive indices are lower
than that of balsam, and from the wide extinctions they would
seem to be nearer to albite than to oligoclase. ‘The felspars of the
ground-mass are short ill-defined laths oriented in all directions,.
with little or no trace of fluidal structure. They have low refrac-
tive indices but small extinctions, and thus appear slightly more
basic than the phenocrysts ; they are still, however, on the albite-
side of oligoclase. \

Iron-ores are scattered through the rocks as fine dust and as.
narrow plates: their quantity is very variable ; and, judging from
the relative abundance of secondary sphene, they are titaniferous. A
few vesicles may be detected, and these are almost invariably filled
with a mass of well-erystallized, secondary, water-clear albite,.
a little secondary quartz, and chlorite. Veins of these materials

1 This type isthat which was described by Rutley (1881) p. 411, Slide No. 3,
as basalt or andesite.

Vol. 67.] SKOMER VOLCANIC SERIES. ; 197

also cut the rocks locally. A little epidote may be present in the
centre of some of the decomposed felspar-phenocrysts, and rarely
fills vesicles. Apatite is a rare accessory.

Structurally, the rocks are in no way related to the andesites.
With a decrease of ferromagnesian and porphyritic constituents (for
instance, E 7046) and the assumption of a good fluidal structure
(for instance, EK 7112), they pass over in the direction of the
mugearites ; and by the occurrence of large olivines they approxi-
mate to the marloesites described below. An intermediate stage

Fig. 9.

) con TO

Ci

ANY, Nay Hl y
fa “f ns oN AN

a iN NY oy
he f at nN Naval ge Lh,
a ae :
ANY Vs ee hes
TWN pas
\ iis rN an iN tae
: oy BNA eee See
BSE ce 6
Re Leas a8 J gi oe) :
AN aC UNE rl tle eS ON NK pee AVA! IAL
the Re eas pone NN Ny ic S% pn

ea co EN YC eels ee 77;
ee as CG

uid STAN x

A=Skomerite, showing subidiomorphic augite and albite-oligoclase felspar-
laths; from the cliffs south of Pigstone Bay (Skomer). Slide E 7090,
ordinary light. X 25 diameters.

B= Mugearite, showing well-defined fluxion-structure, abundan’ iron-ores,
and lar ge apatite close to a small porphyritic augite-crystal ; from 50 yar ds

east of the Limekiln (Skomer). Slide E 7022, ordinary light. x 25
diameters.

may be represented by a flow on the west side of Skomer Island,
just above the North Cliff rhyolites (E 7097), which contains more
olivine than the typical skomerite, but in smaller crystals than
that of the marloesites.

Chemically, the skomerites would compare very closely with the
marloesites (p. 200), from which they differ chiefly in the absence
of the glomeroporphyritic groups of albite and olivine.

scsi ie

a

(e) The Marloesites.
These rocks take their name from the parish of Marloes on the

mainland, where they are well represented.

They occur at

‘SLOJOUIVIP CZ X ‘BOE HT MUS “(Vuelpejurg) spuvxy vusejuop Jo yup Utoysen ‘sotaes
Olfsepue, 9} Woda; ‘osepooqz1oue pu oUIATIO yo YIMOAsIOZUT OTyadydrodoaemMO[S YIM ‘eqttoT[oyuUeG =H
‘sdayOUIVIP CZ X "CEGY W OPUS “(PURIST UpoYssetg) JHH YINOY oy Jo opts uso}som ONY WOT} ‘oyIsoopAVP =

‘STOVOUUVIP GZ X *669 H PUSS

‘(purysyT wpoyssery) uorig Aoaang Jo Yynos souig ‘oyisnv pur avdsyoy osvpoos1jo-971q]v JO ssvt-punoas
poureis-ouy v UT ‘oUTATTO (1038 sydaowopnesd) pue oytqye Jo speqsdao otadydatodosemopy ‘ap 1se0[epT=V

—

. —_
Worece aes

Play) SY

yl Y* node

pL,

hl

ot |
pL

‘OL ‘81g

Marloes Beacon, on the foreshore at Martin’s Haven, at several

localities on Skomer Island, and form the greater part of the

southern side of Grassholm.

Vol. 67.] THE SKOMER VOLCANIC SERIES, 199

They are somewhat pale grey rocks, slightly mottled, very finely
crystalline, and have a splintery fracture. ‘They are compact and
not conspicuously vesicular, except at their surfaces. They are
<learly related to the skomerites, but contain conspicuous pseudo-
morphs after olivine—existing as deep red or bronze-coloured
micaceous aggregates with a distinct sheen. These pseudomorphs
range from 1 or 2 millimetres to a centimetre in width. Felspars
are visible as narrow bright crystals, ranging up to a centimetre
and a half in length, but usually not more than half a centimetre.
The rocks weather with a pale crust, and are often streaked with
hematite in bands 3 to 4 millimetres wide.

Microscopically they show a glomeroporphyritic structure, and
consist of olivine and acid plagioclase-phenocrysts set in a relatively
fine-grained ground-mass containing much augite, acid plagioclase,
and accessory iron-ores. The olivines, which are usually inter-
grown with the larger plagioclase-crystals (fig. 10, A & B, p. 198),
have a tendency towards idiomorphism. ‘They are nearly always
represented by pseudomorphs in serpentine, ferrite, or a bright-
green pleochroic mineral’ produced by the re-absorption of the
external coating of iron-ores. They are only very occasionally
replaced by calcite (E 7037).

The porphyritic felspars are albite-oligoclase ; they are usually
twinned on the Carlsbad and albite laws, and show incipient
decomposition to micaceous aggregates, which render them turbid.
Some of the felspars are perthitic.

The ground-mass, of which the structure hes between inter-
sertal and trachytic, is composed of felspar-microlites enclosing
between them small but abundant subidiomorphic crystals and
granules of augite. Some of the latter mineral, however, as in
the skomerites, behaves ophitically with respect to the felspar-
microlites. The microlites are comparable in every respect to
those of the skomerites (p. 196), but occasionally may be arranged
in curling flows around the larger individuals.

In these rocks there is present, in fair quantity, a brown, probably
soda-bearing, hornblende identical with that mentioned as occurring
in the olivine soda-trachytes (p.192). It has the following pleochroic
scheme :—a, pale reddish-brown ; }, pale brown ; ¢, pale yellowish-
brown. ‘The plane of the optic axes lies in the plane of symmetry,
£,c'=24° approx. ; it is optically positive, and 2 E is greater than
120°. The birefringence is distinctly low, being considerably less
than that of the augite in the same rock. The mineral occurs in
small crystals and grains in the ground-mass, but occasionally is
found within some of the porphyritic felspars (E 6996). It shows
the characteristic hornblende-cleavages.

The vesicles of these rocks are usually small, and filled either
with secondary quartz and chlorite or with interlocking prisms of

i This mineral is green for light vibrating parallel to the cleavages, and
yellow for the direction at right angles. The cleavage-traces mark the posi-
tive direction.

200 MR. H. H. THOMAS ON THE [May ror1,
clear albite. On Grassholm Island in the South Gut a dark-green
ferruginous epidote occupies the cavities in one of these lavas
Mineralogically, these rocks are related to the skomerites, from
which they differ chiefly in the large proportion of olivine and in
the presence of the brown hornblende. They are also related to
the olivine-soda trachytes, which differ from them in containing
little or no augite and possessing a trachytic ground-mass.
Compared with rocks of other districts, ‘they present several
points of resemblance to some of the less acid rocks of Pantelleria,
described by Foerstner,* which stretch from the Montagna Grande to:

VII. VIII.
BOE sac ashecmacete en eee 52°37 49°80
EO) apo dine ae S a Deb capiciae 1:16 1°73
ATO), loitawus dike AUeee 18°05 16°24
BGO a5 cee geese aye eee ie 3°40 3°85
BeQ): i eeee ee ee 4:27 5d
MiO ice ee ee 0:28 0:27
(CaNDO; feck eee not fd. 0°02
Ba Fin ee ee ae 0-02 0°02
CaO? i kd Gee, eee 6-18 401
MoO, iota eneme 5:53 452
1 EX rs See As NDEs COT 2-51
INGE Ot cebeoreteceneeonee ee 4°36 4°88
Tsi2Oy)» Gace soeeae re eer trace trace
HO OMmt LObC 2 eyriona.. 0:32 1:08
H,,O above 105° ©." =... 1°85 2°43
12 0. Patsy rae ee Pp. 0-18 0-18
CO oka anes Mees O17 3°22
Motals Acasa 100-09 100:07
Aaiail.t otrge sates See E. G. Radley, EH. G. Radley.

VII=Marloesite, lava-flow ; south side of Grassholm Island. [Anal. No. 330.
Slide E 6995.|-
VIIIT=Marloesite, lava-flow ; foreshore, east side of Martin’s Haven, Marloes
(Pembrokeshire). [Anal. No. 343. Slide E 7753. |

Monte Gibelé. One of these rocks has been figured for comparison
with the marloesites (fig. 10,C, p. 198). It shows large badly-
formed olivines (between true olivine and fayalite) in association
with anorthoclase. The other porphyritic constituent is a pale |
monoclinic pyroxene, and the ground-mass contains many sub-
ophitic grains of augite, as also a good deal of cossyrite. The
brown hornblende of the marloesites, if original, might be taken
as representative of the cossyrite of the Pantellerian rocks.
Chemically (see Analyses VII & VIII, above), the marloesites
appear to be derived from a magma which differed but little from
that of the mugearites (see Analysis XII, p. 202), except in the
smaller percentage of iron-oxides and the greater percentage of
magnesia: pointing to a smaller proportion of iron-ores and an

1 *Geologia dell’ Isola di Pantelleria’ Boll. R. Comit. Geol. Ital. vol. xii
(1881) p. 528.

Vol. 67.] SKOMER VOLCANIC SERIES. 201

increase in the bisilicates. The percentage of phosphoric acid is

much lower. The alkalies are fairly high, and, considering the

potash as present in the albite-molecule, their percentages would
indicate the presence of 48 per cent. of albite.
The apatite content is only 0-3 per cent. in the least altered rock.

(f) The Mugearites.

The mugearites form a well-defined group which, although con-
stant in structural characters, presents some variation in chemical
composition. In this group are placed typical mugearites with

oligoclase as the dominant felspar, but there are others in which

the felspars may be more acid or more basic. Those with more
acid felspars pass in the direction of the keratophyres and soda-
trachytes, and those with more basic felspars in the direction of
the fluidal olivine-basalts (p. 203).

All these rocks are generally but slightly vesicular, though some

contain vesicles measuring up to 4 or 5 mm. in diameter (E 7078).
They are dark grey, streaked with red, and show a finely crys-
talline structure. ‘They weather to a pale grey or buff, and their
surfaces are often red-stained. The true mugearites, as developed

in the Skomer Series, consist of a mass of oligoclase-microlites,.

arranged with well-defined flow-structure, and a few laths of some-

what larger size with their axes parallel to those of the microlites.
(fig. 9, B, p. 197). The laths average 0°3 millimetre in length,

and have somewhat indefinite terminations.
The ferromagnesian minerals consist of numerous green serpen-
tinous pseudomorphs (well shaped) after olivine, and small idio-

morphic crystals of a strongly coloured augite. Augite also exists

as minute grains between the microlitic felspars. Jron-ores are

abundant, and from the number of regular sections appear to be
magnetite; but the prevalence of granules of secondary sphene

would point to the presence of the titaniferous variety of that
mineral.
Typical samples were collected from the crags north-east of

the Limekiln, Skomer Island (EK 7022, 7023), and from the crags

200 yards south of the flagstaff (EK 7107).

In many rocks of the mugearitic series both augite and olivine
are present in about equal proportions, but in others either olivine
or augite may be developed in excess. In a rock (E7030) from
South Haven north of the Seal Hole, olivine alone is represented by
small idiomorphic crystals (pseudomorphs of calcite) with their
axes parallel to the lines of flow; also a few of the felspar pheno-
crysts are more basic than those of the ground-mass. In the acid
direction, by the diminution of the ferromagnesian constituents,
they pass into rocks characterized by a few augite and olivine-
phenocrysts, but otherwise allied to the keratophyres (for instance,
E 7059). The felspars at the same time become more acid than
typical oligoclase. In the basic direction, if the augite and olivine
increase in amount, the felspars approach labradorite, but are

202 MR. H.'H. THOMAS ON THE [May rory,

still more acid than they should be in a normal basaltic rock.
There is no doubt that these basic mugearites pass gradually into a
group of olivine-basalts which have well-defined fluxion-structure
and a general absence of phenocrysts. Of these more basic mugea-
rites | may mention rocks from south of the Flagstaff, Skomer
(E 7767, Analysis IX, below), and from just above the sediments
in South Haven (E 7014).

TX. x XI. XII.
SILOM eee ie eee 50:19 49-24 49°29 50°06
LW CR en 2-72 1-84 Di, 246
EAE OY 20548 Seem 14:57 15°84 16°66 15°72
10G, Os ee akceec eee 4:39 6°09 7°24 3°94
[RO | apenas eee 8:96 7:18 4-3] 7°63
Sa OY) a a a 0:32 0:29 O55 0°30
(CONT) OTe .n-Ac.8: not fd. Lis 0:04 0:03
WO cre eerie vss ei'n 0°03 0:09 fe 0:03
CAYO) eras Seen 7°60 526 5°63 5°90
DVO) es shite scees Sete 2°79 3°02 2°42 3°82
LONG Si ie a eae 1°53 2°10 1-86 2°16
INE CO Oa Abe omer 4-24 pol 4:98 4°55
TONY. Saisie Aieendener trace ne Moe not td.
HO at JO5°C. o.us. 0°32 1:08 0:34 0°67
H,O above 105° C.... 1-54 Lol 2°11 1:36
ROE e232 ae ean 1 Fol 1-47 0:24 064
OSH Se eee eee 0:03 Ry ni ni. fd
COME wocectette mates 0:02 ane 2:82 1-08
Cliig ect eee ee 0-05 Ate Ye 0-04
ee ot ee eee reer ub O18 :
SH RE Sere, ep 0-03
100°42 sh ae 100°39
essO for Cl ics: 0-01 eas Lac 0-01
Motales ss sats 100°41 ah ioe 100°38
PAINE Peete Soe: E. G. Radley. W. Pollard. W. Pollard. E. G. Radley.

IX=Mugearite (lava); south-east of the House (Skomer). [Analysis No. 346.
Slide E 7767.]
X=Mugearite (intrusion); Skye. [Analysis No. 263. Slide S 13250. ]
XT =Mugearite (lava); quarry, Corston Hill, Corston (Midlothian). [Ana-
lysis No. 247. Slide § 12710.]
XIJ=Mugearite-basalt (lava); hilltop, half a mile north-east of Balbennan,
9 miles south-west of Stirling. [Analysis No. 338. Slide § 14130.]

As regards mineral constituents and chemical composition, the
rocks of this group compare quite well with the mugearites of
Mr. Harker, and therefore they have been classed as such, although
there is little doubt that the Skomer rocks are extrusive and not
intrusive like the mugearites of Skye.

It wiil be seen from the analysis of the somewhat basic
mugearites (I 7767) that the felspar is on the labradorite side
of true oligoclase, and in this respect the rock approximates to the
basalts; but in all other characters, such as the high percentage of
iron-ores, the low percentage of magnesia, and the fairly high
percentage of phosphoric acid, it compares well with the type.

Vol. 67.) SKOMER VOLCANIC SERIES. 203

Structurally, and in the mineral contents, the agreement is close,
except in the absence of the brown hornblende and mica from the
Skomer rocks

(g) The Olivine-Basalts.

The basalts are dark compact rocks, vesicular in their upper
and lower portions, with a finely crystalline aspect and a purplish
tinge (due to the somewhat deeply coloured augite which they
contain abundantly). They are all of the granulitic or hypidio-
morphic type, and consist essentially of magnetite, olivine, augite,
and basic plagioclase.

a is 2 REIL

SA

aly agli
@ | Cas | a
. /

./: See
fi a

| a

i

f is

Y a. i v K A\\\ Z
Aglige Ley <4. mle . ;

A=Olivine-basalt, porphyritic, showing porphyritic labradorite and corroded
and decomposed olivine-phenocrysts ; from the cliff south of Bull Hole
(Skomer). Slide E 7480, ordinary light. x 25 diameters.

B=Olivine-basalt, non-porphyritie, with well-developed fluxion-structure and
granular augite; from inland crags south of the North Cliff rhyolite
(Skomer). Slide E 7102, ordinary light. x 25 diameters.

This may be divided for purposes of description into two types
which merge insensibly one into the other: (a) a porphyritic type,
with porphyritic plagioclase and a ground-mass usually devoid of
flow-structure (fig. 11, A, above); and (6) a non-porphyritic type,
with beautifully developed flow-structure (fig. 11, B).

The porphyritic felspars are all much decomposed, passing into
micaceous aggregates and being replaced by chlorite. They appear
to be a labradorite of medium composition, and in extreme
cases reach 1 cm. in length, but more often measure about 5 mm.

204 MR. H. H. THOMAS ON THE | May ro1r1,

Their boundaries are sharp, they are frequently zoned, and occa-
sionally include grains of augite (for instance, E 7480). Augite
is plentiful, and exists as subidiomorphic crystals, glomero-
porphyritic groups, and sometimes (as in E 7026) as fairly large
idiomorphic crystals penetrated by, but not ophitically enclosing,
laths of felspar. The greater part of the augite exists as small
granules invelved in the plexus of felspar-laths which form the
bulk of the ground-mass. These felspars usually are perfectly fresh :
they average 0-3 or 0-+ mm. in length, and are generally twinned
according to the Carlsbad law. They may show repeated albite-
lamellation if ‘their width allows of it. Their high refractive
indices and wide extinction indicate a labradorite about Ab, An,—
that is, sughtly more acid than that of the phenocrysts,

The olivine usually exists as small idiomorphic crystals in the
ground-mass, about 0-2 mm. long ; but occasionally a single partly
absorbed individual may reach 2 mm. in length (fig. 11, A, p. 203).
This mineral is always represented by pseudcmorphs, either in
limonitic iron-ores, or in chlorite, serpentine, calcite, iddingsite, and
the green pleochroic mineral mentioned above (p. 199).

The iron-ores are well defined, and, from the number of regular
sections, they would appear to be magnetite or titanomagnetite,
probably the latter. There is little or no residual matter, but in
some of the rocks a certain amount of glassy base seems to be
represented by interstitial chlorite which is devoid of the other
rock-constituents. The vesicles never contain zeolites, but are
filled with calcite, secondary silica, chlorite or epidote, and often
lined with sphene (for instance, E7079). Between the porphyritic
and the extremely fluidal types of basalts is a set of rocks
(for instance, E 7058, 7480, etc.) which exhibit practically no
porphyritic felspars, the porphyritic individuals being represented
by a few laths of larger size. All the augite is granular, and the
olivine pseudomorphs are of small dimensions.

The extremely fluidal rocks, of which there are many examples,
are identical in composition with those just described, but differ
in the felspar-laths and plates being slightly smaller in size and
arranged in parallel streams. In a few of these rocks (as, for
instance, EH 7049) the felspars are near to andesine in composition,
and thus they show affinities with the mugearites. These rocks
are prevalent at the Smalls, and might be classed as mugearitic
basalts.

An analysis (Analysis XIII, p. 205) of a typical non-porphyritic
Skomer basalt shows that these rocks are somewhat less basic than
the average olivine-basalt, the silica being about 6 per cent. higher.
Also there isa slight falling-off in the percentage of lime, magnesia,
and iron, with a correspondingly small increase in the alkalies:
pointing to a labradorite-felspar of less basic composition, less
augite, and less iron-ore. However, the rocks are sufficiently basic
to be classed with the basalts, and show no tendency to pass into
rocks which might with any consistency be termed augite-andesites.
According to the classification of Whitman Cross, Iddings, etc., the

Ol, 67.) SKOMER VOLCANIC SERIES. 205
XIII. XLV. XV.

SLO! 5 sats oats sada eae: 53°82 52°68 52:13
dn Bs ae re Ar 1:66 a not dt.
AY, Os ieee wage ee 4°70 14-14 14:87
Be, Os oe aiterae te caeseee 2°39 1-95 not det.
GO! ceeds eee 6°74 o79 11:40
MnO 352 ge cd ceees 0:39 0-44 0°32
(Gla NiO) saa ee, ee es 0:03 Ts
Ba sedge eames sees 0:02 n.d. Sa
CxO cee ene tane 9°03 9°38 10°56
MeO: .b eee «a4 4-84 638 6°46
KO i+) . neat espa 1:85 0:87 0°69
Na Os cee tae 2:79 2°56 2°60
iO! cP cep dak not fd. LEN Fe
HAO ot 10sec ee 0:37 od :
HO above 105° C. 1-59 } eu —_
Ee ices oeeeciae eacnanene 0-10 not det
OO) Missi ae oeeeac 0:10

WMotals'.%. 5.5.2: 100°38 99-79 100-22

A REElee nace tes a E.G. Radley. G.W. Hawes. A. Streng.
XI{I=Granulitic basalt (lava); above the Limekiln (Skomer). [Analysis

No. 344. Slide H 7766. ]
XIV =Dolerite (diabase); Mount Holyoke, Mass. (U.S.A.).
Amer. Journ. Sci. ser. 3, vol. 1x (1875) p. 186.
XV=‘Trap’; Giants’ Causeway (Antrim). Pogg. Ann. vol. xe (1853) p. 114.

G. W. Hawes,

rock of which the analysis is tabulated above would be designated
auvergnose (Symbol III, 5.4.3), and would take its place
among a series of extrusive and intrusive rocks, of which the dolerite
of Mount Holyoke approximates most closely to it in chemical
composition (Analysis XIV); while certain rocks at the Giants’
Causeway, Antrim, resemble it in many respects (Analysis XV).

A striking difference between the Skomer rocks and many of
the Tertiary flows of other regions is the complete absence of
zeolitization, for no zeolites have as yet been detected infilling
the vesicles of Skomer basaltic rocks. The cavities are always
filled with what would be regarded as the normal products of
weathering, such as chlorite, epidote, etc.

(hk) The Olivine-Dolerites.

These rocks are not of very frequent occurrence, but are of wide
vertical and horizontal distribution. They occur at the southern
end of the Smalls; on Skomer in Pigstone Bay above the sediments,
and in the cliffs above the Table, in South Haven above the sedi-
ments, and associated with sediments at the bottom of Matthew’s
Wick; on the mainland at Hopgang.

They exist as masses of much greater thickness (20 feet) than is
usual for the flows; while microscopically they present all the
appearances of intrusive rocks, with the exception of chilled
margins.

In the hand-specimens they are more compact and less vesicular

206 MR. H. H. THOMAS ON THE [May ror1,

than the older basic and intermediate rocks, but the vesicles are
larger and not confined to the margins of the sheets. They often
immediately succeed beds of red clay, or some other sediment which
shows no noticeable induration at the contact.
' Although their intrusive nature is open to doubt, I am led to
regard these dolerites as intrusions on the following grounds :—
(1) their limited occurrence and striking dissimilarity to all the
other rocks of the series; and (2) their thickness and their
indiscriminate association with rocks of widely different types.
The association of dolerite sheets with beds of red clay and the
absence of any important metamorphic effect are points commented
upon by Mr. Harker in connexion with the basic sills of the Western
Isles of Scotland.’

A=Typical ophitic dolerite of the Skomer Series; below the acid series of the
Table (Skomer). It rests upon a bed of red and green mudstone, 2 feet
thick. Slide E7118, ordinary light. x 25 diameters.

B=Coarse ophitic dolerite; from the Anvil, the south-western point of the
Wooltack peninsula. Slide E 7755, ordinary light. x 25 diameters.

The dolerite of Anvil Point is regarded as a lava, for it is
succeeded by a bed of red clay which has evidently been formed in
part from the igneous rock beneath.

Under the microsccpe the Skomer dolerites are finely crystalline
rocks, consisting of labradorite laths, similar to, but slightly more
basic than, those of the basalts, sometimes with a tendency to
stellate grouping, enclosed ophitically by clots of purplish augite.

1 «Small Isles of Inverness’ Mem. Geol. Sury. Scotl. 1908, p. 59.

Vol. 67.] _ SKOMER VOLCANIC SERIES. 207

These clots are circular or elliptical in outline, are separated from
each other, and measure up to 3 mm. across.

The olivine exists as minute serpentinous pseudomorphs exhibit-
ing borders of iron-oxides. JIron-ores with regular sections are
plentiful, and apatite is an abundant accessory.

The coarse dolerite (fig. 12, B, p. 206) consists of a pale purple
augite in ophitie plates, with laths and lath-shaped porphyritic
crystals of labradorite-felspar. It contains fairly large pseudo-
morphs after olivine in serpentine, chlorite, and delessite, or the
green micaceous mineral mentioned above (p. 199), veins of which
also traverse the rock.

Chemically, the Skomer dolerites are closely related to the
Jedburgh type of dolerite of Central Scotland, described by Prof.
W. W. Watts’ and later by Mr. E. B. Bailey,” and would have a
silica-percentage of about 46. The titanium, iron, lime, and
magnesia would all be high, but the percentage of phosphoric acid
is probably greater than in the Jedburgh dolerites.

Structurally, the Skomer rocks are almost identical with a rock
from a point 700 yards west of Dumbeath, Stirling Castle (S 12568),
but are slightly less rich in olivine.

VI. Tuer AssocratEp Cruastic Rocks.

The sediments associated with, and occurring within, the Volcanic
Series form one main group, about 450 feet thick, which stretches
in a strong ridge across Skomer (see map, Pl. XI). These rocks
are thrown northwards by a fault which passes from South Haven
to North Haven and between the Rye Rocks. On the mainland
these sediments form a much-faulted belt near the northern coast
between Martin’s Haven and Hopgang, and also occupy Cable Bay
and Mouse’s Haven in the Wooltack peninsula. They are well
exposed on Skomer in the Wick, at Welsh Way and at the base of
Highclff, in North and South Havens, and at Protheroe’s Dock on
the north side of the Neck. They consist, in the lower part, of
coarse rhyolitic breccias and conglomerates alternating with white,
buft-coloured, or green quartzites ; in their upper part, they consist
of alternating quartzites and red clays—the latter becoming pre-
dominant at the top. These red clays are exceptionally well
displayed in the sections at the Wick, South Haven, and Protheroe’s
Dock.’

Quartzites belonging to other horizons in the series occur in
the extreme south of Skomer and in the Mewstone Channel ; below
the dolerite of Pigstone Bay and the trachyte of North Castle; at
South Castle on the Neck; on the south side of Midland Island ;
on the north side of the Deer Park at Wooltack; on the high ground
west of Martin’s Haven; and as a thin band on the northern coast

ae Sir Archibald Geikie’s ‘ Ancient Volcanoes of Great Britain’ vol. i (1897)
Dd. .

Pie Geology of the Country around Glasgow’ Mem. Geol. Sury. [in the press].

> For a detailed description of these sections, see E. W. Small, 1899-1909,
pp. 12-13.

Q.J.G. 8. No. 266. P

208 MR. H, H. THOMAS ON THE [May rgi1,

between Martin’s Haven and Hopgang. A beautiful rhyolitic con-
glomerate is exposed on the shore in the west side of Martin’s
Haven. I have been unable to. prove the existence of grits in the
Garland Channel (Skomer), as suggested by Mr. Small. All the
half-tide rocks examined were of rhyolitic character; but some
were well bedded, and presented the appearance of sediments when
looked at from the top of the cliff.

Red clays on other horizons are frequent, and occur in Pigstone
Bay, below the rhyolite of Tom’s House; at South Castle; a little
way below the red rhyolite of the Neck and Midland Island; in
Mouse’s Haven; and in association with the dolerites of the Anvil.

All these rocks were undoubtedly deposited by water, and,
although the red clays, which range from 1 to 7 feet in thickness,
are similar to the boles of other districts and are undoubtedly due
to the weathering of basic lavas, they have not been found in place
except in a few imstances, but have been deposited by water, as is
shown by the common occurrence of spangles of mica. The upper
portions of the flows on which they rest occasionally appear to be
roughly conglomeratic, the igneous fragments being deeply stained
and interbedded in a red clay matrix (as, for instance, Pigstone
Bay, the south side of Midland Island, and the upper dolerite of
the Anvil). The red clays present the most conciusive evidence
of the subaérial character of the igneous rocks, and for the most
part are associated with the more basic members of the Volcanic
Series. Even when the clays are absent, many of the lava-surfaces
show a conspicuous red staining, such as is noticeable on the south
side of Grassholm, and on the dip-slopes of Skomer Head, the Neck,
and Wooltack Head.

Examined microscopically, the rhyolitic breccias of the main
sediments of Skomer Island might be described as arkose, almost
all the fragments, which measure as much as 7 inches across, being
of igneous origin. These fragments consist of pieces of soda-
rhyolite, broken spherulites, keratophyres, soda-trachytes, and other
Skomer rocks, in a fine felspathic matrix consisting of quartz and
broken crystals of plagioclase. 7

The finer sediments range from felspathic grits to quartzites.
They are made up of subangular quartz, angular soda-rich felspar,
and a few fragments of trachytic and other acid volcanic rocks
set in a more or less silicified clastic matrix.

True pyroclastic rocks, as has been remarked (p. 185), are very
poorly represented in the Skomer Series. One of the best series
of tuffs is that exposed in Pigstone Bay. ‘The rocks are well
bedded, reach 8 feet in total thickness, and consist of numerous
broken acid-plagioclase crystals, as also fragments of perlitic,
spherulitic, and microlitic rhyolites, set in a highly felspathic paste
composed largely ot felspar fragments and microlites. The small
patches of silicified clastic material on the surfaces of certain of
the keratophyres have already been mentioned (p. 185).

On the mainland tuffs of intermediate character and several feet
thick have been noted beneath the quartzites of Cable Bay in the
cliffs of Wooltack.

Pegg ee ee

Vol. 67.] SKOMER VOLCANIC SERIES. 209

VII. Tee CaemicaL AND MINERALOGICAL CoMPOSITION OF THE
Lavas.

Chemically and mineralogically, the rocks of the Skomer Series
show some marked peculiarities. Primarily they form a group
rich in soda and poor in lime, a fact which shows itself in the
prevalence of soda-rich plagioclase felspars.

The abundance of soda-rich felspars and the unusual character
of many of the rocks might reasonably, in view of recent research,

Fig. 13.— Diagram illustrating the percentage chemical composition
of the Skomer ignéous rocks.

suggest that some of the rocks were originally more basic, but
had undergone a process of albitization similar to that described
by Messrs. Bailey & Grabham.' In the Skomer Series, however, if
albitization has taken place, it has been complete and has left no trace
of intermediate stages as an indication of the change. Again, if
the rocks are albitized, albitization has been restricted to certain

* Geol. Mag. dee. 5, vol. vi (1909) p. 250.
P2

210 MR. H. H. THOMAS ON THE [May rort,.

flows and groups of flows: for rocks with much albite are often
to be found between flows of which the felspar is all labradorite.
Also the rocks rich in albite, as regards structures and the nature
and arrangement of the ferromagnesian minerals, are quite different
from the more basic rocks which presumably would represent their
unaltered prototypes. Secondary albite, when it does occur in these
rocks as veins and infilling vesicles, is, as usual, water-clear and
quite different from the felspars of the phenocrysts, etc., which
show turbidity due to incipient decomposition. Iam led, therefore,
to regard the chief mineralogical and chemical peculiarities of the
Skomer rocks as primary, and to consider the Series in part to be
rich in original soda and to present Pantellerian affinities. The
Series, as a whole, may be regarded as a curious interdigitation of
alkaline and subalkaline types.

The accompanying diagram (fig. 13, p. 209) makes it appear
that the rocks represented are a mixture of types converging in
the basic direction, for the analyses when plotted seem to indicate:
that the rocks belong to two distinct but overlapping series.

The dolerites and basalts may be considered normal augite-
labradorite rocks; but all the other igneous rocks show mineralogical
and structural peculiarities, the most remarkable of which is the
widespread occurrence of albite and albite-oligoclase felspars in
intimate association with large porphyritic crystals of olivine, as.
in the olivine-trachytes and marloesites, and with abundant augite
in the skomerites.

Another peculiarity worthy of note is the occurrence of the
brown hornblende in the olivine-trachytes and marloesites.’ In
the more acid rocks the felspars are hardly ever zoned, but are
sometimes beautifully microperthitic—teatures which are common
in rocks of the alkaline class. here are no felspathoid minerals.
or zeolites.

VIII. Tue Sequence in TIME OF THE VARIOUS Rock-Typzs.

The sequence presented by the Skomer Series, as made out on
the mainland of Pembrokeshire, differs somewhat from that obsery-
able on Skomer Island; but the differences may be explained by
the eastward thinning of the series as a whole and the overlapping
of certain horizons by others. Considering the mainland, the
lowest member of the series is a group of rhyolites exposed at
Musclewick beyond the eastern edge of the map (Pl. XI), and
followed presumably by the mugearitic group of Wooltack Head.
This in turn is succeeded by the intermediate group of the northern
cliffs which underlies the main sedimentary group. The highest
rocks consist of olivine-basalts, and overlie the sediments. The
general succession, therefore, is from acid to basic.

On Skomer Island a much greater thickness of volcanic rocks
may be studied. The lowest rocks visible are those of the rhyolitic
group of the mainland, which here reaches some 500 feet in thick-
ness. It is followed by an insignificant group of intermediate

Wel 07. | SKOMER VOLCANIC SERIES, 211

rocks which give place to the lower basalts, about 220 fect thick.
These basic rocks are followed by the main group of intermediate
javas, represented by skomerites, keratophyres, and trachytes.
There is then a return to basic conditions, as testified by the
great mass of mugearites and basalts which occupies the centre of
the island. A glance at the map will suffice to show that there
appears to bea regular succession from acid to basic, and then back
again trom basic to acid rocks ina rhythmic sequence. Important
rhyolitic groups occur at four horizons, and in almost every case
are led up to by increasingly acid, and followed by increasingly
basic rocks.

It will be seen, therefore, that where the greatest thickness of
igneous rocks can be studied there is a frequent repetition of types
without any abrupt change in the character and composition of
consecutive flows. These abrupt changes, however, become more
and more obyious as the distance from the vent increases, and as
thinning and overlap within the series become more pronounced.

LX. Summary AND CoNCLUSIONS.

The Skomer Volcanic Series, which takes its name from Skomer
Island off the coast of West Pembrokeshire, has a minimum thick-
ness of 2900 feet and a lateral extension of over 26 miles from
east to west, from the neighbourhood of St. Ishmael’s, on Milford
Haven, to beyond the Smalls in St. George’s Channel. The positive
evidence places the age as pre-Upper Llandovery, but the indirect
and negative evidence would suggest that the volcanic rocks belong
to the lower part of the Arenig Series. The rocks are for the most
part subaérial lava-flows of extreme thinness and great lateral
extent. The subsequent intrusive phase is but feebly represented
by a few dolerite sills, and possibly by a mass of soda-felsite.

There is a paucity of true pyroclastic rocks, but sediments in the
form of breccias, conglomerates, quartzites, and red clays, with a
total thickness of 450 feet, mark a constant horizon near the centre
of the series. The red clays which also occur on other horizons,
although partaking of the nature of plinthite, are not in most cases
formed by the decomposition of the basic rocks in place, but are
water-deposited. 7

Of the igneous rocks eight types with several variants have been
detected, representing rocks which range from soda-rhyolites to
olivine-dolerites. Chemically, they embrace types containing silica-
percentages as high as 80 and probably as low as 46.

In the more acid members of the series the percentage of total
alkalies ranges as high as 8°82, but soda is always in excess of
potash. The soda-rhyolites, soda-trachytes, and the two new types
skomerites and marloesites belong to a soda-rich series, and
present affinities with the alkaline rocks of Pantelleria. The
mugearites, basalts, and dolerites belong to the subalkaline class,
and may be compared with the plateau-basalts and basic sills of
Tertiary age in the West of Scotland. Thus we have here a mixture

PA MR. H. H. THOMAS ON THE [May 1911,

of alkaline and subalkaline types. Mineralogically, the more acid
members of the series are peculiar in the abundance of soda-rich
plagioclase felspars, and in the association of these minerals with
porphyritic crystals of olivine, hypersthene, and augite. The
lava-groups and the supposed sills thin out in an easterly direction
from Skomer, where the greatest thickness is displayed, a feature
which suggests a vent, or series of vents, lying to the west of that
island.

In order of extrusion, except where the series is thinning, there
appears to be a sequence from acid to basic and basic to acid.
Thus there is a frequent repetition of the same type of rock, but
seldom any extreme change in the characters and composition of
contiguous flows.

In conclusion, I wish to take this opportunity of tendering my
grateful acknowledgments to Mr. F. T. Howard and Mr. E. W.
Small. for most liberally placing at my disposal all their microscope-
slides and much useful information which they had collected; to
Mr. J. J. Neale, J.P., of Cardiff, the lessee of Skomer, for the many
kindnesses which he showed me during my residence on the island;
and to the Elder Brethren of Trinity House and Captain Mayar for
allowing me to proceed to the Smalls Rocks on board the 8.8. Siren.
I am also much indebted to Major EK. Howell and Mr. T. Picton,
who accompanied me to Skomer; and to Prof. 0. T. Jones, who
worked with me over the difficult sections of the Wooltack
peninsula.

EXPLANATION OF PLATE XI.

Geological map of Skomer Island and the adjacent Pembrokeshire coast,
on the seale of 6 inches to the mile=1 : 10,560.

Discussion.

Mr. J. F. N. Grenn welcomed this paper as explaining a
difficulty. On Ramsey Island, north of Skomer, certain rocks had
been mapped, and repeatedly described as pre-Cambrian and basal
Cambrian. It was now clear that these were simply the Skomer
Series, the ‘ conglomerate ’ (of which the speaker showed specimens)
being a nodular rhyolite. This discovery greatly simplified the
geology of Ramsey, and enabled the speaker to confirm the Author’s
views as to the age of the Skomer rocks—since in Ramsey Island
they rested, with apparent conformity, on shales belonging to the
zone of Didyimograptus bifidus.

Dr. J. S. Frerr remarked on the interest of the paper as con-
firming the work of previous investigators, and describing types of
igneous rocks not hitherto recognized.

In his work on the Lower Silurian voleanic rocks of the Southern
Uplands of Scotland, Dr. Teall had shown that a series of diabases,
diabase - porphyrites, pillow-lavas (rich in soda - felspar), kerato-
phyres, and soda-felsites oceurred—an association very similar
to that described by the Author from Skomer, and belonging in

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o GLACIAL. SILURIAN.

SKOMER SERIES

= Soda- Trachyte,Skomerite
Rheolike Trachyte & Marioesite undivided) Marloesite

Quartzites of eas a.
Glacial Drift edged thus Upper Bandovery. Silurianfundivided) Basalt.
ae]

Basalt Dolerite. Quartzites, ete

of Skomer Senes

Waybench

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GEOLOGICAL MAP OF SKOMER ISLAND, , ‘We a f o
and the adjacent» ) Fibs
—— PEMBROKESHIRE COAST.

Mew Stone

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Bemrose & Sons ™ Derby & London

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Vol. 677] SKOMER VOLCANIC SERIES. 213

all probability to the same epoch of volcanic activity. From
Mevagissey, in the south of Cornwall, Dr. Teall had recognized
diabases, pillow-lavas, keratophyres, and soda-felsites belonging to
a series which also was Lower Silurian. The continuation of
these rocks to the south-west had been investigated by Mr. J. B.
Hill and the speaker on the northern boundary of the Lizard
district ; and there again was an assemblage of diabases, pillow-
lavas, and ‘soda-felsites,’ the last-named being rather coarse-grained,
but having a composition very similar to some of the Author’s
rocks. Hence, it seemed established that one characteristic of the
eruptions of this period was the development from one magma of
basic types of rock (diabases, etc.) along with acid and intermediate
types that were especially rich in soda-felspar.

The rocks called marloesites and skomerites by the Author
were of great importance, as examples of igneous rocks of rather
basic composition in which the dominant felspars contained a high
proportion of albite. Long-continued investigation of the older basic
rocks of Britain had convinced the speaker that in a vast number
of cases the only felspar which they contained was albite. In part,
this mineral was no doubt primary, but in large measure it was of
secondary origin. Albitization, or the replacement of other felspars,
especially lime-felspars, by albite was a process that had gone on in
Britain ona very large scale. In Cornwall and Devon, for example,
by far the greater number of the ‘ diabases’ had been completely
albitized. It was by no means easy to lay down the principles on
which it could be determined whether the soda-felspar in any one
of these Paleozoic igneous rocks was primary or secondary... But the
speaker had had an opportunity of examining the Author’s slides
~ of marloesite and skomerite, and he agreed that the alkali-felspars
of these rocks were for the most part original; and, although albiti-
zation had taken place to some extent, especially in the phenocrysts,
it had not essentially modified the characters of the rocks.

The recognition of mugearites in Skomer Island was a welcome
addition to our knowledge of British petrography. First established
by Mr. Harker, only seven years ago, to include a limited number
of Tertiary rocks in the island of Skye, this group had proved to
have a wide distribution in the Carboniferous volcanic areas of
Scotland. Mr. Barrow had found them in East Lothian, Mr. Bailey
and the speaker in Midlothian, and Mr. Tyrrell in the Glasgow
district ; now, for the first time, they had been discovered in Wales.

Mr. Evan Smart was glad to find that the observations made
some years ago by Mr. F. T. Howard and himself had been largely
confirmed. The Author had, however, very greatly extended these
observations, and he congratulated him. Referring to Mr. Green’s
remarks, as to a nodular lava on Ramsey Island being mistaken
for a sedimentary conglomerate, he noted that a similar error had
been made by earlier observers on Skomer : for, on the old Geological
Survey map, the whole of the spherulitic rhyolite of Tom’s House
and the Basin in the south of the island was shown as sedimentary.
The true character of this rock was, however, recognized so long

214 THE SKOMER VOLCANIC SERIES. [May 1911,

ago as 1881 by Frank Rutley, from specimens collected by Sir
Andrew Ramsay. Though the question did not lie strictly within
the scope of the present paper, he would like to ask the Author
whether he had come to any definite conclusion as to the source
of the foreign boulders of hornblende-biotite-granite found on
Skomer.

Mr. R. F. Gwinnett asked whether it was not desirable to use
the term ‘lime-bostonite,’ or even the more definite name of
‘menaite,’ as introduced by Prof. W. C. Brégger, in place of the
very vague term ‘ keratophyre, for the rocks which the Author
described as being identical with lime-bostonite.

The Prestpent (Prof. Warts) called attention to the presence of
olivine in the dolerites and basalts of the Skomer area—an unusual
feature, so far as his experience went, in rocks of this age. He
did not recognize, in the slides exhibited by the Author, any great
resemblance between the bedded volcanic rocks and those of the
zone of Didymograptus murchisoni on the Welsh borders. ‘This
difference might, perhaps, be accounted for by the different age of
the Skomer rocks.

The AvtHor, in reply, thanked the speakers for their appre-
ciative remarks. With regard to the granite-boulders mentioned
by Mr. Small, he considered that they, in common with many on
the mainland of Pembrokeshire, derived their origin from the South
of Scotland; they were associated with other rocks of Scottish
derivation. The term ‘keratophyre’ had been used by him for
certain rocks, classed as such by Rosenbusch in his most recent
work; but he recognized that it was an ill-defined rock-group, and
far too elastic to be of much classificatory value. He had not used
the rock-name ‘lime-bostonite’ for these rocks, as their structure
was not bostonitic, and also it seemed unadvisable to use the name
‘bostonite’ for extrusive rocks.

Vol. 67.] THE SALOPIAN OF CAUTLEY AND RAVENSTONEDALE. 215

6. The Zonat CrassiFication of the Satovtan Rocks of Cauriey
and RAavyENSTONEDALE. -By Miss G. R. Warnry and Miss E. G,
Wetcu. (Communicated by Dr. J. KE. Marr, F.R.S., V.P.G.S.
Read January 11th, 1911.)

{[Prare XII—Geoxogicat Mar.]

ConrenTs.
Page
i’ Tntrodnehionmane, Titera pare .22 0... cox. adeteeveeocesease 215
II. The Wenlock Beds of (a) The River Rawthey Area ... 217
(Oo) Wandale (ill. hess. oi 223
(@pllarterciell 36.2 ok: fadcodens-l 227
I1I. The Ludlow Beds of (z) Wandale Hill .................. 229
(>) Ravenstonedale Common ... 230
PURO sacle ito it, 25 ReSho Opt rapine cat ee Ene eer eee ee 231
Weal eran eae seen see oes Shue bee a letb ene 234

I. Iyrropuctrion anp LITERATURE.

We were induced by Dr. Marr to undertake the examination of
the Salopian rocks of the area under consideration. He had failed
in former years to obtain any zonal succession of the rocks of
Wenlock age in the Lake District, owing to the cleaved nature
of the rocks of that age above the lowest beds containing Cyrto-
graptus murchisont. An examination of the less cleaved repre-
sentatives of the Wenlock Beds near Cautley had convinced him
that a succession might be established there, similar to that described
in Scania by Tullberg, and in Wales and the Welsh borderland by
Mrs. Shakespear and Miss Elles.

Our study of the Wenlock and Ludlow rocks of the Cautley and |

Ravenstonedale area has convinced us that these beds are capable
of a division into zones, although some of the zones recognized
farther south apparently do not persist when traced northwards
to this district.

The Cautley and Ravenstonedale area is situated north of
Sedbergh ; its northern and eastern limits are defined by Carboni-
ferous rocks, but on the west it is continuous with the Salopian
of the Lake District.

The physiography of the district and the features due to ice-
action have recently been described by Dr. Marr & Mr. Fearnsides*:
it will suffice, therefore, to mention here that the area is a very
hilly one, the fells often rising steeply from the 600- to the
1750-foot contour-line. North-west of the Rawthey the hilltops
are everywhere formed of hard grits of Ludlow age, while on the
south-east intrusive igneous rocks occupy the highest ground.

' Q. J. G. 8S. vol. lxv (1909) pp. 587 e seqy.

216 MISS @. R. WATNEY AND MISS E.G. WELCH oN THE [May 1g1t,

The general structure of the district at the present day is
complex.’ Originally, there was probably simple folding which
was subsequently affected by faulting. Most of the Cautley area
is occupied by the Wandale-Hill synecline with a north-by-east
and south-by-west axis, and the Bluecaster syncline having a
north-north-east and south-south-west axis; these are separated
by the Murthwaite-Park anticline, which passes into the Sally-Beck
fault close to Narthwaite.

In both cases half only of the syncline remains. The Sally-Beck
fault has cut out the north-western limb of the Bluecaster syn-
cline, and the western part of the Wandale-Hill syncline has
been faulted out by the Wandale-Hill fault, which has thrown
down the Upper Wenlock and Ludlow Beds against the Stockdale
and Coniston Limestone Series.

Numerous other small faults intersect the area, which are easily
traced by zonal mapping.

Though exposures are well seen in many streams, yet no section
shows the complete succession through the Salopian. Throughout
the area the Wenlock and Ludlow strata differ markedly in their
' lithological characters: the former may be described as banded
argillaceous flags, while the Ludlow rocks are tough, micaceous,
sandy flags interstratified with unfossiliferous bands of grit.

Literature.

The Salopian rocks of this district have been briefly described in
‘The Geology of the Country around Kendal, Sedbergh, Bowness,
& Tebay’ Mem. Geol. Surv. 1888, in which a classification into
two groups is made: (1) Coniston Flags, and (2) Coniston Grits.

‘The Geology of the Country around Mallerstang,’ Mem. Geol.
Surv. 1891, deals more particularly with the Cautley and Howgill
area. The conformable relation of the Coniston Flags and the
Stockdale Shales and the lithological characters of the beds are
described. Monograptus priodon and M. colonus are recorded from
the Coniston Flags, and M. colonus from the Coniston Grits.
Unidentified graptolites are said to occur in the Bannisdale Slates.

The most important paper from our point of view is by Dr. Marr,!
on the Wenlock and Ludlow strata of the Lake District, in which
he divides the rocks into the following zones :—

, Bannisdale Slates. Zone of Monograptus leintwardinensis.

Lower | 5 = s
LupLow. i Gee cosa Beds. i Zone of Monograptus bohemicus.

» Middle Coldwell Beds. Zone of Phacops obtusicaudatus.

Loner Colds pae: Zone of Monograptus nilssoni (2).
Zone of ? Cyrtograptus carruthersi.

WENLOCK.
Brathay Flags. Zone of Cyrtograptus nuurchisoni.

' Geol. Mag. dec. 3, vol. ix (1892) p. 534.

Vol. 67.] SALOPIAN ROCKS OF CAUTLEY AND RAVENSTONEDALE. 217

We have recognized the following zones in the Salopian rocks of
Cautley and Ravenstonedale :—

D, Zone of Monograptus leintwardinensis Hopk.

Lower Lupnow. ~ : é
D, Zone of Monograptus nilssoni Barr.

Phacops-obtusicaudatus Bed.
[ C, Zone of Cyrtograptus lundgreni Tullb.
C, Zone of Cyrtograptus rigidus Tullb.
C., Zone of Monograptus riccartonensis Lapw.
Lc Zone of Cyrtograptus murchisoni Carr.

WRNLOCK ....... :

Il. Tae Wentock Bens.

The Wenlock Series is well exposed in three distinct areas in
the Cautley district: namely, in the neighbourhood of the Rawthey,
Wandale Hill, and Harter Fell. The rocks present three fairly
distinct. lithological types: (1) blue flags, (2) yellow sandy beds,
and (3) red flags and grits; but in each case the same zones occur.
The whole thickness of the Wenlock Series exposed in this area
does not exceed 900 feet.

It has been possible to work out the approximate thickness of

the zones in the Rawthey area as follows:
Thickness in feet.

Zone of Cyrtograptus lundgrent ........5.....0ceeee eee 300 to 400
Zone of Cyrtograptus rigidus ..........0cccceeeeeeneeees 178
Zone of Monugraptus riccartonensis ....c.cccceeeeee ee 160
Zone of Cyrtograptus murchisoni ...........0.ceceeee 100

(a) The Rawthey and the Western Slope of Bluecaster.

We have obtained our most complete sections through the
Wenlock Series in the neighbourhood of the Rawthey. We therefore
propose to describe the Wenlock Beds of this area in detail, and
to give only general descriptions of the confirmatory sections
elsewhere. Near the Rawthey each zone is exposed, and a con-
formable succession is obtained downwards into the Browgill Beds,
and upwards into the Phacops-obtusicaudatus Bed, which here, as
elsewhere in the Lake District, separates the strata of Wenlock
from those of Ludlow age.'

The Wenlock Series occupies a narrow strip of country, from
Birks Field Beck north-eastwards to the mouth of Wandale Beck.
There is uniformity in the character of the beds throughout this
area. They are massive jointed flags, finely banded, blue-grey
when unweathered, and becoming brown on exposure to weathering
agencies.

As has been noticed elsewhere,” the argillaceous character of the
rocks has so greatly favoured cleavage that it is always difficult
to obtain a good surface along the bedding-planes ; even when such

1 J. E. Marr, Geol. Mag. dee. 3, vol. ix (1892) p. 540.
2 «Geology of the Country around Mallerstang’ (Expl. of Quarter Sheet 97
N.W.) Mem. Geol. Sury. 1891, p. 34.

218 MISS G. R. WATNEY AND MISS E.G. WELCH ON THE [May 1911,

a surface is obtained, the fossils in places are almost unrecognizable.
The complicated system of faulting shows that movements have
considerably affected the area; the presence of felsite and lampro-
phyre dykes is also of interest.

We have observed that the lowest Wenlock Beds invariably have
their fossils preserved in relief, and this is a distinctive feature of
these beds throughout the whole of the Cautley area.

An ascending section shows a greater tendency towards flagginess
in the rock, and the introduction of pyrite in the form of abundant
tiny cubes causes the strata to weather to an ochreous colour. The
highest beds are characterized by irregular calcareous concretions,
varying from a few inches to a foot in diameter; the banding
is very marked, and the rocks weather to a light brown.

On the north and west the Sally Beck and other faults bring the
Wenlock Beds against strata of their own age, or against the Brow-
gill and Ludlow ; but on the Bluecaster side there is a conformable
passage downwards into the Browgill Group. The general dip of
the beds is 30° north-north-westwards: they strike, therefore, across
the gills which run in a north-westerly and westerly direction ;
but, although sections are numerous, they are, with the exceptions
of those in Middle and Near Gills, never complete. As a rule, the
fossils occur in bands in the rock, or even along definite bedding-
planes. There seems to be no means, however, of distinguishing
between the fossiliferous and the unfossiliferous bands.

It is from a study of the exposures in the Bluecaster gills and
their fauna that we have become convinced that the Wenlock Beds
of this area are divisible into four zones, namely :—

(1) Zone of Cyrtograptus lundgrent. Cy.
(2) Zone of Cyrtograptus rigidus. C,.

(3) Zone of Monograptus riccartonensis. Cy.
(4) Zone of Cyrtograptus murchisoni.. C,.

Bluecaster Gills: @) Par Gall:

The exposures in Far Gill are large and fairly fossiliferous ; but
the rocks are so highly cleaved that the fossils are almost obliterated,
or seen only as smudged impressions. The highly cleaved state
of the rocks may be due to the proximity of a fault on the north
of the gill.

Cyrtograptus-murchisont Zone (C,).—Just above the old
road splintered blue flags crop out in the gill-bed, dipping at 36°
north-west by north. The fossils found were typical of the zone:
Cyrtograptus murchison, Monograptus priodon, and Orthoceras
occur in abundance. Below the old road two felsite-dykes cross
the gill; the rocks are baked by these, and for a distance of
100 yards no fossil is to be found. These beds presumably belong
to the zone of Monograptus riccartonensis.

The rocks in the higher part of the gill break with greater ease
along the bedding-planes, and are ochre-stained.

Vol. 67.| SALOPIAN ROCKS OF CAUTLEY AND RAVENSTONEDALE. 219

Cyrtograptus-rigidus Zone (C,)—At the bend of the
stream the lithological character of the rock changes once more to
blue-grey banded flags, much affected by cleavage. Along one
bedding-plane Monograptus flewilis is abundant, and it is the only
fossil that is easily recognizable. As we have found throughout
the Cautley area that J/. fleailis is common only in the C.-rigidus
Zone, it may be taken as an index of that zone.

A characteristic feature of this zone is the introduction of

secondary calcite along the joints and bedding-planes of the rock.

Cyrtograptus-lundgrent Zone (C,).—100 yards down stream
the beds dip 20° north of north-west at 24°, and maintain their
dark coloration and cleaved character. ‘They yield many specimens
of Monograptus vomerinus., Some 30 yards from the upper field-
wall, however, the beds change; they become tougher, and weather
to alight brown. IM. fleningu var. ¢ and M. dubwus were found
here. The presence of the former fossil and lithological change in
the rocks indicate the C.-lundgrent Zone.

(i) Middle Gill.

Cyrtograptus-murchisont Zone (C,).—The felsite-dyke of

the old road has baked the Murchisont Beds of Middle Gill; but
just below the road a small exposure yields good specimens of
C. murchisoni, Monogr aptus pr todon, M. vomerinus, and Letiolites
gemitzianus.

The zone extends down the gill for a distance of about 60 yards,
and other small exposures indicate that Cardiola and Retiolites
geimitzianus are abundant in the higher parts of the zone.

Monograptus-riccartonensis Lone (C,). —The passage into
this zone is marked by a complete change in the fapna. The
name-fossil becomes very abundant’; indeed, slabs of rock are often
covered by it, to the exclusion of any other. The fossils are, on
the whole, badly preserved, as the result of cleavage. A list of the
forms found is enumerated in Tabie I (p. 222). The beds dip
at 35° north- westwards.

Cyrtograptus-rigidus Zone (C,).—This zone is well exposed °

on the right bank of the gill, and extends down stream for 60 yards
below the little waterfall.

he rocks dip at 34° north-north-westwards ; they are highly
cleaved, and contain abundant cubes of pyrite, which cause them to
weather to a bright orange colour. ‘The higher part of the zone is
characterized by the blackness of the fresh rock, and by the abundant
development of secondary calcite. Monograptus flewilis is crowded
along definite bands in association with (. rigidus, M. vomerinus,
M. hisingeri, M. dubius, and M. flemingiw var. 6; this last fossil
becomes more abundant in the highest part of the zone.

is

220 MISS G. R. WALNEY AND MISS E.G. WELCH ON THE [May 1911,

Cyrtograptus-lundgrent Zone (C,).—The lower part of
Middle Gill is largely covered by drift, and the few exposures are
poor. They yield M. flemingit var. 6 and M. dubius, and dip at
41° north-north-westwards.

A large quarry between Middle and Near Gills on the Sedbergh
road yields the associates C. lundgreni, M. flemingit var. 3, and
M. dubius. The rock is a very massive blue flag.

Gu) Near Gill.

In Near Gill the exposures are smaller than in either of the
gills already described, but the fossils are in a better state of
preservation, and all four zones are well seen.

Cyrtograptus-murchisone Zone (C,).—Some 30 yards
below the old road, a small exposure on the left bank of the gill
vields C. murchisont and the forms associated with that fossil.
The beds are much affected by the ‘old road dyke,’ and have been
converted into pale, flinty, unbedded rock.

Monograptus-riccartonensis Lone (C,).—For the next
100 yards the only exposures are very small ones in the gill-bed.
It is difficult to identify the fossils, but, from their crowded occur-
rence and general form, they can be recognized as MZ. riccartonensis.

Cyrtograptus-rigedus Zone (C,).— At the bend of the
stream ochre-stained beds form a small cliff on the right bank, and
a scree-slope on the left bank; their dip is 32° north-westwards.

A richly fossiliferous band ocente in the cliff, containing many
examples of C. rigidus and Monograptus flexilis; on the opposite
bank OC. linnarssoni, C. rigidus, and M. fiexilis occur abundantly.
Retiolites spinosus is also common—this fossil has hitherto been
recorded in Britain from the Lower Ludlow rocks only. About
25 yards lower down, an exposure in the left bank yields C. ragidus
and Monograptus flemin gu var. a.

The higher part of this zone occupies two scree-slopes 100 yards
down stream; here the rocks are characteristically pyritous, and
contain M. fleningw var. a in abundance.

A small lamprophyre-dyke occurs in the left bank of the gill just
below the screes: its trend is north-west by west.

Cyrtograptus- lundgreni Zone (C,).—Below the dyke pyrite
is no longer seen in the rock, which assumes the normal cleaved
appearance. The most common species is WV. flemingw var y, here,
as usual, characteristic of the lower part of the zone. Some yards
farther enon CO. lundgrent occurs in the left bank. Down stream
the rocks become less massive, aud show a greater tendency to
break along the bedding-planes.

The beds threughout the zone dip at 26° north-westwards. Near
the Sedbergh road they become lighter in colour and more sandy.

Vol. 67.] SALOPIAN ROCKS OF CAUTLEY AND RAVENSTONEDALE. 221]

M. flemingti var. y, C. lundgreni, and M. dubius are all contained
in these highest beds.

Apart from the three gills mentioned previously, numerous small
streams which run from Bluecaster into the Rawthey are, with a
few exceptions, nameless. We have, therefore, for the sake of
convenience, named them alphabetically (see map, Pl. XII).

One or more of the Wenlock zones crop out in each of these
gills, and, as the results of our work in them are summarized in
Table It (p. 222), itis only necessary here to mention a few points
of interest.

(iv) West Gill.

This gill, which flows into the Rawthey below Low Haygarth,
is of importance, not only because three of the zones are exposed
in its banks, but on account of the conformable succession into
the Browgill Beds which can be traced in the southern branch of
the gill. Cyrtograptus murchisont occurs in the bed of the gill
20 yards below a cowshed; at the same distance above the shed the
Browgill Beds crop out.

The Riccartonensis Zone (C,) comes on 6 yards below C. murchi-
soni. Its beds are almost black, veined with calcite, and speckled
with cubes of pyrite; their dip is 5° west of north-west at 55°.
The lower part of West Gill is largely occupied by two felsite-
dykes, the lower of which is continuous with the ‘ old road dyke’ of
Near, Middle, and Far Gills.

Exactly 52 yards from the Sedbergh road, and just below a
small lamprophyre-dyke, the rocks dip at 21° north by west, and
yield the fauna of the C.-lundgrent Zone (C,).

The only other exposures that show the succession from the
Browgill into the Wenlock Beds occur—

(1) Ina small dry valley running westwards in continuation of the head
of Gill H; and

(2) 20 yards below Ecker Secker Bridge.

Both these sections show the marked lthological and faunal
changes which take place between the beds.

In Ecker Secker Beck the Cyrtograptus-murchisont and Mono-
graptus-riccartonensts Zones occur, but the Cyrtograptus-rigidus
Zone seems to be cut out by faulting. At the hedge on the right
bank of the beck there is evidence of faulting; the dip of the
beds changes suddenly from 35° to 75° north-north-west wards, and
there is considerable local development of secondary calcite in
ramifying threads and veins. Some yards lower down the rock
becomes concretionary, and Monograptus flemingu var. 6 occurs.
The presence of another fault at the mouth of the beck is proved
by a fault-breccia seen in the left bank, accompanied by large veins
and bands of calcite.

TaBLE J.—GRaAPTOLITES FROM Far, MIppLE, and NEar GILLs.

|
© #1). Zone Zone of Zone of Zone of
Species and Varieties. Cyrtograptus Monograptus | Cyrtograptus | Cyrtograptus
| murchisoni. triccartonensis| rigidus. lundgreni.
C,. C:. C3. Cx
C = very common. | ; wees
¢ = common. Nas A {fae eke
R=very rare. Rey sea mett Lae 7S | PS ee |
r=rare. Noe tie Sot Se Py ca Kone aes ~ } <S laa eA
a(S (4a |e)2 (es | See ee
| |
Cyrtograptus carruthersi Lapw. ......... (ieee al ek cosas ae, Re hee sek c
Cyrtograptus lundgreni Tullb................ Pt pea Ree) (eS fa] en | C
Cyrtograptus linnarssoni Lapw. .........| 2... |... | wee Poe | wee | C ae
Cyrtograptus murchisoni Cary. ... 2.22.0... eee) Oe 4
| Cyrtograptus murchisoni, var. crassius- | |
culus Tull. . | r if eee | ae
| Cyrtograptus rigidus ‘Toll. sae é | Cringe Set
| Monograptus flemingii Salt. var. a Elles . | i Wp ose ee | sais
ss ss 2). penn | > | C (ac oe tes
| ED) ry) ry) S90 e 5 | tee | © C
| s: 5 pO Heck [nee | fees Peek | ccd | Pe
iManograptus jleailis BALES, <l cc. spepeee cael |; asst | aes ates] MR Wetman bane © :
wilnnagraptus capillaceus Tullb. coc. cescs\ coe | ss | see oe | eae | DO ee ee de
(Monograptus dubius Suess: ....c-tcissecs| | s. | ds Poe | C1 OL... ) CG aiae acme
Monograptus priodon Bronn ............... ate CO | CR. | ee Sane ie
Monograptus riccartonensis Lapw.......... hee en ena! Faia pa e( tae sh
Monograptus hisingeri Carr. var. ......... hse me Men PE CHI Clay HER eo on
Monograptus vomerinus Nich.var.a Elles| ...| C CY]... C}CIC|Cc]C Bite ey
95 e a aed Mee 5G Cates daria Ce | Cs tae i
Retiolites geimitztanus Barr. ..............| C | C |} C J... | ... Pe re a
Retiolites spinosus Wood Y Gash eoemaltame orn) oie | | Col) sa heres
TaBLEe I].—GRaprToLitEs FROM BLUECASTER GILLS.
| Zone of | Zone of Zone of
Cyrto- | Mono- Zone of Cyrto-
graptus | graptus | Cyrtograptus rigidus. | graptus
Species and Varieties. murchi- | riccar- lund-
soni. | tonensis. gren.
C. Cee C3. C4.
C = very common. & 5 5
© = common. = 2 3
R = very rare. oe . | RQ ; ; : - - | @
so SS a S 5 O 5 <ze || (25) | [ea ics ico) a
Sao lao | or Sas Oo |e
Cyrtograptus linnarssoni Lapw................ : C vee
Cyrtograptus murchisoni Carr. ...............| C | ¢ | tee
Cyrtograptus murchisoni, var. crassius- |
culus Tullb. . cart ime eae [, Bes Mores bahia
Cyrtograptus rigidus Tullb: 1... CHcey FoI Ne oa ee
Monograptus flemingii Salt. var. se ‘Elles ~ ColiCri ica ae
2) 29 29 oy) 39 ee c c BAS
De) bb} 23 33 O 33 R pee C C
Monograptus flexilis Elles Le See eal C
Monograptus dubius Suess PTE ee hic|| nh eee (ae CG, | C
Monograptus priodon Broun ..................| © | C |...
Monograptus riccartonensis Lapw. ......... Sah ame (sO bts ;
Monograptus hisingert Carr. var. Ronpace © c
Monograptus vomerinus Nich. var. @ Elles .. Cc ae :
Re ie Pe hn a eee r as
Retiolites g geinitzianus De LeP a Camera eta ans tan fra ot On

Vol. 67.]| HE SALOPIAN OF CAUTLEY AND RAVENSTONEDALE. 223

The River Rawthey.

The part of the Rawthey under consideration lies between the
mouth of Wandale Beck and Cock’s Dub. The Wenlock zones exposed
on the western slope of Bluecaster should in turn appear in the
banks of the Rawthey ; but, as the result of faulting, the succession
of zones is irregular.

Above Handley’s Bridge the three lowest zones strike across the
Rawthey in a south-easterly direction, but they are cut off at the
bridge by a fault trending north-west and south-east.

Both the Cyrtograptus-murchisoni (C,) and Monograptus-riccarto-
nensis Zones (C,) near the mouth of Wandale Beck have yielded
the characteristic graptolites enumerated in Table I (p. 222).

The zone of Cyrtograptus rigidus (C,) which conformably succeeds
them down stream yields few fossil remains ; and those which do
occur, Monograptus flewilis and WM. flemingw var. a, are poorly
preserved, owing to movement in the rock close to Handley’s
Bridge, where there is evidence of both folding and faulting on a
considerable scale. At Handley’s Bridge the beds change their
dips from south-south-west to west by north, and they are seen
to strike across the river, and then to bend round towards the right
bank.

Although exposures are good below Handley’s Bridge, there is
a scarcity of paleontological evidence ; two zones only are found.
The Cyrtograptus-lundgrent Zone (C,) extends from Handley’s
Bridge to Cautley Thwaite, with the exception of some yards below
the mouth of Backside Beck, and is conformably succeeded by
the zone of C. rigidus (C,). Below the fault at Low Wardses the
C.-lundgrent Zone (C,) again appears.

The general dip of the rocks throughout is in a north-north-
westerly direction, although variations occur in different parts of
the river where it is crossed by faults, as, for example, at the
mouth of Backside Beck, where the dip changes to south-west by
south, and above High Wardses Bridge, where it is 50° east of
north.

The evidence for the establishment of the succession lies below
the mouth of Backside Beck. The beds dipping 22° west-north-
westwards are yellowish and sandy when fresh, and yield Phacops
obtusicaudatus in abundance. It will be shown elsewhere that
beds containing that trilobite are immediately overlain by the
lowest Ludlow, Zone of Monograptus nilssoni (D,); hence in this
part we have the completion of the Wenlock succession.

The four Wenlock zones are exposed in the Bluecaster Gills,
and are conformably overlain by the Phacops-obtusicaudatus Bed
as seen in the Rawthey.

(0) Wandale Hill.

The Wenlock and Ludlow rocks form the greater part of the top
and the eastern slope of Wandale Hill. These beds are limited on
the west by the Wandale-Hill fault, which runs in a north-north-

Q.. 4G. S. No. 266. Q

224 MISS G. R, WATNEY AND MISS E.G. WELCH ON THE | May 1911,

easterly and south-south-westerly direction, and brings them
abruptly against the Stockdale Shales and the Coniston Limestone
Series. On the south the Sally-Beck fault forms the boundary of
the Wenlock Beds: this runs close to, and almost parallel with,
the Rawthey.

Fig. 1.—Section through Wandale Hill.

Quarry

Backside

[ Horizontal scale: 6 inches=1 mile. |

The eastern slope of the hill shows a conformable passage down-
wards from the Wenlock into the Stockdale Shales and the Coniston
Limestone Series. All these beds sweep round from a north-easterly
to an easterly direction below Adamthwaite, and join the rocks
exposed in Harter Fell.

Adamthwaite Sike, which forms the northern limit of Wandale
Hill, runs through drift, and it is therefore impossible to determine
the trend of the beds near the northern limit of the Wandale-Hill
fault.

The Ludlow rocks occur as an oval outcrop capping Wandale
Hill, and a section showing the Ludlow resting upon the highest
Wenlock Beds is seen on the west side of the hill; but on the east
side, in the gills near Wandale Farm (which we have named W,
and W,) only the three lowest Wenlock zones are exposed. The
Wenlock strata of this area are yellow, banded, sandy flags, passing
up into the blue banded flags typical of the Rawthey area.

Cyrtograptus-murchisona Lone (C,).— The boundary
between the Browgill and the Wenlock Beds occurs 40 yards below
the Fell wall on Kast Wandale.

The lowest Wenlock Beds strike parallel to, and are well exposed
in many small sections along, the Wandale road. The conformable
relation of these C.-murchisont Beds to the Browgill Beds below is
well seen in three small gills north of the Narthwaite larch wood and
in the numerous gills near Wandale. Their passage upwards into
the Monograptus-riccartonensis and Cyrtograptus-rigidus Zones is
best shown in two small gills north of Wandale Farm.

In one of these, W,, the base of the Cyrtograptus-murchisoni
Zone is exposed 20 yards below the road, and its upper limit oceurs
at the road. The rocks, dipping at an angle of 40° north-west by
west, are massive, banded, grey and yellow, sandy flags. The

Vol. 67.] SALOPIAN ROOKS OF CAUTLEY AND RAVENSTONEDALE. 225

fossils, as elsewhere in this zone, are preserved in relief. Table IIL
(p. 226) shows that the characteristic faunal assemblage of the
Murchisoni Zone occurs here, Cyrtograptus murchisoni and
Retiolites geinttzianus being especially abundant. Orthoceras
primevuin is also of common occurrence.

Farther north is Gill W,, in which good exposures of this zone
again occur. ‘The zone has ‘been traced to a distance of 30 yards
above and 25 yards below the road. The rocks here are roughly
cleaved, and dip at an angle of 32° north-north-westwards.

onograptus-riccartonensis Lone (C,).—Good exposures
of this zone are found in Gills W, & W,, and isolated exposures
yielding the type-fossil occur farther north in the hillside.

South of Gill W, no exposures of this zone are found, but the
outcrop of beds evidently narrows towards the Sally-Beck fault, as
is indicated by the close proximity of the Murchisont and the
Lundgrent Zones in the larch-wood.

In Gill W, the transition between the Murchisoni and the
Riccartonensis Zones is abrupt, and marked by both a lithological
and a paleontological change. On the lower side of the Wandale
road the grey banded rocks containing the Murchisoni fauna occur ;
while on the upper side these are replaced by pale-yellow sandy
rocks, in which the bedding-planes are crowded with Monograptus
riccartonensis. The zone extends 48 yards up the gill, the rocks
dipping at an angle of 17° north-west by west.
~ Guill W, also gives a good section through the Riccartonensis
Zone, but ‘only the lower part yields many fossils. The rocks dip
at 31° north-westwards, and retain their sandy character ; they
pass, however, occasionally into a darker and more banded type, as
in the hillside exposures towards Adamthwaite, and in Wandale
Beck 300 yards below Adamthwaite.

Cyrtograptus-rigidus Lone (C,).—This zone is well ex-
posed in Gills W, and W,, and in an old quarry-road towards
Adamthwaite. Southwards also it has been possible uD) trace the
zone in a small exposure in Wandale slope.

The lower part has the same yellow sandy character as the
Monograptus-riccartonensis Zone; but, when traced upwards, it
gradually passes into a tough, blue, banded rock, which weathers
brown.

Characteristic fossils are abundant. In Gill W, the beds dip at
42° west-north-westwards, and extend to the top of the gill; but
numerous loose blocks on the hillside above, containing fossils
common to the zone, indicate that only the lower part is exposed
in the gill.

Gill W, extends higher up the hillside, and it has therefore been
possible to trace the upper parts of the Cyrtograptus-rigidus Zone
here. The transition between the C.-lundgreni and the C.-rigidus
Zones is, however, hidden.

Qa 2

226 MISS G.R. WATNEY AND MISS E.G. WELCH ON THE [May rorr,

Cyrtograptus-lundgreni Zone (C,).—This zone is best
exposed in a small stream-section occurring in a larch-wood above
Handley’s Bridge. The rocks dip at 25° west by south, and are
massive, blue, banded flags containing the characteristic zonal
graptolites.

There are no other exposures of this zone on the eastern slope
of Wandale Hill, but the fossils may be picked up in abundance at
the gathering-grounds of the gills.

A massive grey-green grit occurs near the top of Wandale Hill:
it is unfossiliferous, and probably forms part of the Lower Ludlow
Series, since nowhere in the area does a grit appear in the Upper
Wenlock.

Taste II]—WanpDALE-HILL WENLOCK GRAPTOLITES (GrLLs W, & W,).

Zone of | Zone of 7, ¢ Zone of
Species and Varieties. Cyrto- | Mono- Cn Cyrto-
graptus | graptus| ~2" i graptus
C= very common. murchi- | riccar- te lund-
c =common. sont. tonensis. | 1 1I°°MS gren.
Y= rare. o 2 Cs C4

W,.|W2. |W ,.| Wo.) W,.| Wo. W,.| Wo.

Cyrtograptus linnarssoni Lapw.............| ... | ... J ..°| 2 J .. | ©
Cyrtograptus murchisoni Carr. ............| C | C :
Cyrtograptus rigidus Tullb. ............... a c c
Monograptus capillaceus Tullb. ......... ee ae Ted We ees en
Monograptus dubius Suess ............ 2.000 eee) ees ees let eG
Monograptus flemingii Salt. var. 6 Elles. mee ee er yo!)
2” ” 3 2 B 29 see see see ste or iste Sais Cc
33 33 33 9 a 39 C
Monograptus flexilis Elles .. ie Cc

Monograptus hisingeri Carr. var. ......... Ce One eae
Monograptus priodon Broun
Monograptus riccartonensis Lapw.

Q
Q

@
QQ! «

Monograptus vomerinus Nich. var.a Elles} C | C Me

ise? A ea ” ROL (55 tee c
Retiolites geinitzianus Barr. ............... C Sa (ere) | Sac D
TREULOVIGES SPULOSUS NV OOWteemrene es (tecn.-:|...2. | aet- fea ee Oe

West Wandale.

On the west side of Wandale Hill the Wenlock again crops, out,
and the Lundgrent Zone (C,) is found overlain by the Monograptus-
nilssont Zone (D,) of the Lower Ludlow. The Lower Wenlock
zones are cut out by the Wandale-Hill fault, which has let down
the Upper Wenlock and Ludlow Beds against the Browgill Beds
and the Coniston Limestone Series.

The only exposures occur in a small gill, which flows down from
the site of an old quarry above Narthwaite to join Backside Beck.
Where the gill crosses the Mountain-View Road, the Coniston-
Limestone Beds are faulted against the Wenlock strata. These
appear as blue finely-banded flags, with many concretions. The dip

Vol. 67.| SALOPIAN ROCKS OF CAUTLEY AND RAVENSTONEDALE. 227

is at 59° south-west by south, and cleavage has been induced in the
beds. ©. lundgrent and Monograptus flemingii vars. y & 6 were
found a few yards above the road. Yellow sandy beds yielding
small brachiopods and M. dubius overlie the C.-lundgreni Zone (C,),
and above follow darker gritty beds containing graptolites of the
M.-nilssoni Zone.

(c) Harter Fell.

The top of Harter Fell is occupied by Lower Ludlow rocks, and,
on passing down its southern and south-eastern slopes, we traverse
the Wenlock, Browgill, and Llandovery Beds in turn.

Numerous little gills, making deep gashes in the hillside, afford
the best exposures of the Wenlock Beds. The fossils of the lowest
Wenlock are preserved in the typical solid form, and the beds
themselves are blue-grey banded flags. A lithological change comes
in with the appearance of Monograptus riccartonensis ; the rocks
weather with a red stain, and are gritty. The red coloration
becomes accentuated as the beds are traced upwards into the red
Ludlow grits.

The Wenlock zones sweep round Harter Fell in a semicircle,
_and are cut off abruptly on the east by the Sally-Beck fault. They
all crop out within the short distance of 230 yards. Their pre-
vailing angle of dip is a high one, and the direction varies
between north and north-north-west. The Browgill Beds are
exposed below the Wenlock in Five Gills ; elsewhere the strata are
hidden by grass and drift.

Each individual zone differs little from those previously de-
scribed. Therefore only a list of places is given, where each zone
is exposed :—

C.-murchisoni Zone (C,) ......00+ Gill 2 (Five Gills).

M.-riccartonensis Zone (C,) ...... Gills, 2, 3, 4, 5 (Five Gills), Odd
Gill, and at the waterfall in Wan-
dale Beck below Adamthwaite.

C.-rigidus Zone (Cg) «........0000ee Gills 5, 4, 5 (Five Gills).
C.-lundgrent Zone (O,) .........4.- Gills 2, 3, 4, 5 (Five Gills). Gills
1] & 2 (Three Gills).

West of Harter Fell the Wenlock Beds are covered by drift,
the only exposures being those mentioned in Odd Gill and Wandale
Beck. They reappear, however, in Spen Gill. Here the Browgill
Beds pass up conformably into blue banded flags containing Mono-
graptus priodon, Cyrtograptus murchisoni, and Retiolites geinitzianus.
Higher in the gill the rocks have suffered much from cleavage, and
the only fossil fragments found were unrecognizable.

At the waterfall calcareous concretions appear, and with them
Monograptus flemingu var. ¢ and M, irfonensis. Phacops obtusicau-
datus was found jn a yellow sandy bed occurring between the top
of the C.-lundgreni Zone and the base of the I.-nilssona Zone.

228 MISS GR. WATNEY AND MI&8 E.G. WELCH ON THE {| May 1911,

II. Tue Luptow Bens.

The Lower Ludlow rocks occupy the greater part of the high
ground of the Howgill Fells; the lower beds pass up conformably
into the Bannisdale Slates, which in their turn pass beneath the
Carboniferous rocks of Rayenstonedale. An outlier of Ludlow
rock, which is not indicated on the Geological Survey map, occupies
the summit of Wandale Hill.

The Ludlow rocks of the Howgill area consist largely of banded,
micaceous, sandy beds alternating with grit-bands; these serve to
distinguish the Ludlow rocks from the argillaceous flags of the
Wenlock Series. Graptolites are fairly abundant in the lowest
Ludlow Beds, but usually they are poorly preserved owing to the
coarse nature of the rock; exceptions are found in those bands
where the fossils occur in relief.

Dr. Marr’ has shown that the Ludlow rocks of the Lake Dis-
trict may be divided into two main zones, those of Monograptus
bohemicus at the base and M. leintwardinensis at the upper limit.
Our work in this area supports this earlier classification.

In addition to the graptolite fauna, lamellibranchs and brachio-
pods occur in much greater abundance here than in the Wenlock
Flags.

The Ludlow Beds are most fully developed in the Ravenstone-
dale Common area; but, since the watershed occurs in the Ludlow
rocks, no complete section is found, and hence it has not been
possible to trace the passage between the Nilssonc and the Lewnt-
wardinensis Zones. There is evidence of considerable folding on
both sides of the watershed, and this is further complicated by two
sets of fault-lines which run at right angles to one another, and
the great shatter-belt described by Dr. Marr & Mr. Fearnsides.’
Traced upwards from the yellow Phacops-obtusicaudatus Bed, the
rocks may be divided into two groups :—

(1) Blue-grey banded flags alternating with unfossiliferous blue micaceous
beds which are cleaved and silky in appearance, succeeded by red
micaceous grits and flags, with few fossils.

Throughout this group fossils belonging to the Monograptus-
nilssont Zone are found.

(2) Grey banded flags, red grits, and blue slaty beds (the Bannisdale
Slates) in which I. leintwardinensis is common.

The outcrop of the greater part of the J/.-leintwardinensis Zone
is not inserted in the accompanying map (Pl. XII), as it occurs
farther north, and agrees practically with the line between the
Coniston Grit and the Bannisdale Slate on the Geological Survey
map. The most fossiliferous development of the lowest Ludlow
occurs on Wandale Hill.

1 Geol. Mag. dec. 3, vol. ix (1892) p. 541. “
2 Q.J.G.S. vol. lxv (1909) pp. 589 et segqe

Vol. 67.] SALOPIAN ROCKS OF CAUTLEY AND RAVENSTONEDALD, 229

(a) The Ludlow Beds of Wandale Hill.

The summit and the north-western slope of Wandale Hill are
formed of Lower Ludlow strata, the outcrop being semi-elliptical ;
on the east and south-west the lowest beds pass conformably
downwards into the Wenlock Series. On the west, however, they
are faulted against the Browgill Beds, and farther north along the
Spengill Road are faulted out. Only the Monograptus-nilssoni Zone
is found on Wandale Hill.

The exposures occur in an old quarry above Narthwaite, just
below the Spengill Road; and in the heads of three gills which
cross the same road farther north.

Narthwaite Quarry.—The lowest beds crop out imme-
diately below the west side of the quarry-wall; they are tough,
blue, banded flags, rather coarse and sandy in texture, yielding
Monograptus dubius in association with JV. colonus.

Above the wall fossils typical of the J/.-nilssont Zone are
abundant. ‘They occur in relief in a band of blue flags, above
which sandy and minutely banded blue flags dipping at 36° south-
west by south are exposed; the fossils in these are preserved as
impressions only. Jf. colonus, MW. bohemicus, and Cardiola inter-
vupta are met with most frequently.

The higher beds in the quarry are grey-green, slaty, unfossili-
ferous flags.

Taste [V.—WanpaALeE-Hitt LupLtow GRAPTOLITEs.

Zone of
Monograptus nilssoni.

Species and Varieties.

C = very common. = > |
© = common. Pa =) ere : Pay
pee cates = Nn oo |
i — Tare; | Eo | = == =
Wei ey o
3 wei, | ——
Monograptus bohemicus Barr. ............000600ceceee| C De are =o
Monegraptus chamera BI 7.6/2. aks) CR yi C C
2 + var. salweyi Hopk. ......... i anes fie C
Monograptus colonus Bary. ............ 2.6.4. nie C C
Monograptus comis Wood nae ab a
Monoyraptus dubius Suess een c os c
Monograptus nilssont Barre... 0) deco tec desis che sone r r ee
Monograptus, reemert Warns 2... 2 2 ode seems Caceres fh) obs c
Monograptus varians var. pumilus Wood ........... z | x pes c
Monograptus wandalensis, sp. NOV... 2.6... cee vee! } a
Retiolites nassa Holme i): ts An fee eupees sade sede | €

Spengill Road Gills.—The Ludlow strata in these three
gills are sandy, banded flags of a higher horizon than those exposed
in Narthwaite Quarry; when weathered the rocks assume an

230 MISS G. R. WATNEY AND MISS E.G. WELCH ON THE [May rg11,

ochreous colour. The heads of all three gills rise in the A/.-nilssonr
Zone, as will be seen from an examination of Table IV (p. 229).
Fossils are fewer than in the Narthwaite-Quarry beds; but in the
third and largest gill they are well preserved and fairly abundant.

Two exposures of a fine grey-green grit—one in the site of an
overgrown quarry near the summit of the hill overlooking Adam-
thwaite, and the other in the hillside above Narthwaite, probably
represent a higher horizon of the AZ.-nilssont Zone.

(b) The Ludlow Beds of Ravenstonedale Common.

The beds, dipping in a general north-north-easterly direction, are
exposed in numerous streams flowing northwards and southwards
from the watershed, and in small quarries occurring in the hill-
sides.

Spen Gill and Dale Gill.—The Lower Ludlow rocks are
well exposed in the higher part of Spen Gill, which flows southwards
from the Howgill watershed, and in Dale Gill flowing northwards.

At the source of Spen Gill good specimens of Monograptus
bohenvicus and M. colonus were obtained in some abundance, from
a micaceous band of rock which weathered red; and throughout
the upper part of the gill occasional fossiliferous bands are found
in the blue banded grits, yielding JZ. colonus and J. remert.

Across the watershed small scree-slopes occur in the hillside of
Green Bell; paleontological evidence still points to the continuation
of the M.-nilssoni Zone (D,), for graptolites of the colonus type pre-
served in relief are common. .

At the source of Dale Gill similar rock crops out; but the
fossils are poor, and only preserved as impressions. The head of
Stwarth Gill has yielded Cardiola, Orthis, and Pterinea; and « few ©
badly preserved graptolites occur in a red grit which alternates
with red micaceous flags.

Lower down the gill the rocks again change to blue-grey grits,
sandy beds with lamellibranchs and trilobites (Acidaspis), and
smooth unfossiliferous flags. No graptolites were found until |
50 yards below the junction of Stwarth and Dale Gills, where a |
highly fossiliferous blue band crops out at the bend of the river, |
containing Monograptus leintwardinensis with many lamellibranchs
and trilobites. ‘The beds dip at 36° east-north-eastwards.

Gais Gill and Adamthwaite Road.—A small quarry
situated in Adamthwaite Bank, overlooking the right tributary of |
Gais Gill, has yielded abundant specimens of Monograptus leant-
wardinensis, which tend to be preserved in relief in a hard, banded,
blue-grey flag. No further exposures occur until this tributary
joins with Long Gill, forming Gais Gill. Here the rock dips at 87°
north-north-eastwards; it consists of coarse and fine red grits
alternating with flags in which J/. bohemicus, JZ. colonus, and

Vol. 67.] SALOPIAN ROCKS OF CAUTLEY AND RAVENSTONEDALE, 231

Cardiola interrupta are common. These fossils all indicate the
M.-nilssoni Zone.

The gill flows practically on the strike cf these rocks as far as
the footbridge on the Adamthwaite Road. A small exposure ot
typical hard, blue, banded Wenlock rock occurs here in the left
bank of the stream, and has yielded specimens of J/. flemingii
var. a, which is a typical fossil of the C.-rigidus Zone. Beyond
this point, for a distance of 170 yards, no good exposure occurs
until a quarry on the Adamthwaite Road is reached, in which
fossils characteristic of the J/.-nilssont Zone are fairly numerous.
The rock is similar to that previously described in the upper part
of Gais Gill, and dips at an angle of 20° north-north-eastwards.
Beyond this quarry the surface is again hidden by vegetation,
until exposed in a cutting in the roadside, opposite a shed south of
Banks Farm, which again yielded J/. leintwardinensis. The rocks
dip 39° north-north-eastwards. This succession of zones, with the
rocks all dipping in a general north-north-easterly direction, seems
to point to isoclinal folding in this region.

Isolated exposures.—The zones of Monograptus nilssoni and
M. leintwardinensis are seen in numerous other stream-sections,
but only a few present fresh features of interest.

Stonely Gill and Two Gills rise in Harter Fell, and show large
exposures of Lower Ludlow rocks, which only differ from those pre-
viously described in their red coloration. MJ. bohemicus, M. colonus,
and I. remeri were found, in addition to Cardiola interrupta and
Orthoceras ; these fossils clearly indicate the zone of J/. nilssoni (D,).
The l.-leintwardinensis Zone (D,) was met with in Bowderdale
Beck and in Pinskey Gill, just north of Pinskey Bottom : the latter
locality yielded MM. leintwardinensis and its variety incipicis ; these
two varieties have so far not been found together.

IV. Correnation.
(1) The Wenlock Beds.

A glance at Table V (p. 233) will serve to show that there is
abundant evidence in the Cautley area for a zonal classification of

the Wenlock Beds. ach of the four zones is clearly marked oft

from the other three by a distinctive fauna; also the fossils which
give their names to the zones are strictly limited to one zone, and,
with the exception of Cyrtograptus lundyreni, range through the
entire zone.

We have preferred to retain C. lundgreni as the zone-fossil of
the highest Wenlock Beds, as Miss Elles has already chosen it for
beds of the same age in the Welsh Borderland. For purposes
of identification of the zone, however, the varieties of Monograpius
flemingri y & 6 have been most useful to us.

an

232 MISS G.R. WATNEY AND MISS E.G.WELCH ON THE [ May 1911,

As Cyrtograptus linnarsson is found only in association with
C. vigidus at Cautley, we have correlated our Regidus Zone with
the zones of C. linnarssont and C. rigedus of Builth.

The assemblage of forms below the C.-rigedus Zone do not
justify the interpolation of another zone in Cautley between this
and Monograptus riccartonensis. We have recognized four zones
only (see Table V, p. 233).

TABLE V.—DISTRIBUTION OF THE GRAPTOLITES IN THE SaLopran Rocks oF WALES
AND THE WELSH BOoRDERLAND, AND IN THOSE OF CAUTLEY AND
RAVENSTONEDALE.

e |
WALES CAUTLEY

and the and
| WeEtsH BoRDERLAND. JRAVENSTONEDALE
Species and Varieties. | Ludlow. Ludlow.
= i: lz |2 | al os $3
X S S | = S Ns x QS
C = very common. ee I Pee SEP SS) eS MS
© = common. : = | = | = S “ SS = Ss
= very rare. Sh) 8.212 ols Sy) & S48 Oe
eae BER SR ER SIRS as ms |
ao 3 Sis 2s els Sea] 38 | Be |
PS SSR SPARS Pes 2°8
B.S 7) ernie >| gens oe
N IN IN |IN. IN N N
Monograptus bohemicus Barr. Cri Fea C
Monograptus chimera Barr. Cl Car: C
- a var. a wpe
ue var. salweyi Hopk. e | C
Monogr aptus colonus Bary. ........0.....005 Cay C |
» __ Var.compactus Wood aed ue
Monogr -aptus comis Wood etree r ¢
Monograptus erimitus Wood... ee.) | |e.
Monograptus dubius Suess. .............:....| C | e¢ | ¢€ C
Monograptus gotlandicus Perner Desh Ceaan RI ee RR of fe. ele. |
Monograptus leintwardinensis Hopk. MR ot ccs oll rane eee Ine C
3 VANS CeCUpIeHSAWOOdh | .2. bn. Nyce hae mee c
Monograptus gilssone Barn, eee eee ee |) Ct Aine R
Monograptus remeri Bary. ......... 0.0.2... ee ell Gea eee c
Monograptus scaniceus Tullb. ..28: 22.024)... | € | 6
Monograptus twmescens Wood . Ce ae
e var. minor Mé Coy Bee ONG SP Cae laa He
Monogr aptus MLCUNUS Meiners |e ee Te ees hots, ih ae 62 ae
Monograptus wncinatus var. im icropome )

Jekel ne r R
Monograptus uncinatus var.orbatus W aul Y
Monograptus varians Wood .................. c

en abe aVals. at WV OOUe eee: 15
be ee 5 WV OOG nee pee Chalshaeey
be on ir. pumilus Wood | eek | Ca oa c
Monograptus pulgares Woods in: execs, Cra
3 Val. ae VOOd) eee Hie Feel Ge ds gl leona eet Set ee
a: és bee een essen ab ERR Sogn areas lh) hs ies ans) Rael
Monograptus RUAIUEELENSUS: ASP VON ee ret ae | cee feces || Daehn C
Retiolites nassa Holm. ...........0..c000c00 0 ae |PRt < dl aero c foe
Retiolites spinosus Wood a. ed ane
| |

a

Vol. 67.] SALOPIAN ROCKS OF CAUTLEY AND RAVENSTONEDALE. 233

TasieE V (continued).

Cyrtograptus flaccidus Tullb. .............. 2. ©

WALES CAUTLEY
and the and
Wetse BorpERLAND RAVENSTONEDALE.
Species and Varieties. Wenlock. Wenlock.
fa Vane eS ane he. pe (si /s
Seni, eS i ie is ls 1S
S < S ~ oa iS ~ ~
: So lwaall eSa 4 SS SN Ss
C = very common. = Sal SSSv ee pe PS PS | Se LS
> 1 S2/S4/5../5 1S FS | S215 [Ss
¢ = common. &../S2/$8/S2/5 |S [S./S2/S |S
R Sis SiS Sse S-sfe 8/5 SE Sis
i = very rare. IS sis SiSeiSsls -|SsiSsis sl S88
tees SEA SISECZIS SISOS 2 Siogios
* = rare. Bs SS St re eS RS Fr Pe Bete ae a
[3 S18 $/S S/S SSSR S/S ESR
lo S| S|} Sloss Slo Sho Slo Sla Slo &
esiSsiseayesig-e13 S's sifsl2s1g8
lige = Ss So @lo™ o> aes BeS(e2/S8 s™=
N N WS SN IN N IN IN IN IN )
-_- - —__—_ ‘as reel aa ee: oe
Cyrtograptus carrutherst Lapw. .....-....2-| «|... | 2. |. | aw | C |
es Pe ae ae i
| | ©

Cyrtograptus linnarssoni Lapw. ............) 0 | wee |v dime
Cyrtograptus lundgreni Tullb. ............ =i Cee | Spiel ween EAM 8
| eee eee

Ee C
Cyrtograptus murchisoni Cary. .....-...... eg aes C |
- Ae var. erassiusculus
yet oie ae Ch aed Ride ana Buren ne eres | easel OE al eee
Cyrtograptus rigidus Tullb. «2.2.2.0... OSCE Peart | on vag ren ae Ogg a pa eg
Cyrtograptus symmetricus Elles ............ Sat bel Amen Wa tam MES ere eee ee
Cyrtograptus tubuliferus Perner......... A ge 2h Ieee oA eg Named el
Monograptus basilicus Lapw. .:...........,€ | ¢ C OG ef C [ss ee
Monograptus capillaceus Tullb. ......... We sei oh Call lect ae eee Pe ane ha eee ie aa
Monograptus dubius Suess ..............6.4. cial a cial fe, Cadel ab Sod Uo © | C ORE a Oa a ©
Monograptus flemingii Salt var.0 Elles ...) ... |... | 2. | we | oe | C C
55 pe Sot San ees resets pecs HBr | WoO: x: ih
5 me so eens ness Te SeeRa Heese i (Olean ear r t ic | r
Pig: oes es) jae c Oe ty a ee “le
Monograptus flewilis Ble re Se PS VR ae EN 8 | fe! aie
Monograptus hisingeri Cary. var. ......... Ce ie Gaya C 1 CR om
Monoygraptus trfonensts Elles. 25220..0:--) 22. | a. [ae fue f erp € r
Monograptus jekelé Perner .......-....2.....) 22. | ..3 |=. Oh cami ht coe oa |
Monograptus priodon Bron ............... Cole a ae ited Car om ;
Monograptus retroftexus Tullb. .............] ... | ... |... |... | C [ese |
Monograptus riccartonensis Liapw....... R!c|R ee fa a ae

Monograptus testis Barr., var. inornatus |
Mess .3 205.2 |
Monograptus vomerinus Nich. var. r. 2 Elles %

39 33 33

aca:
©

Retiolites geinitzianus Barr. eM ree
Retiolites spinosus Wood .................2.4 om oer
HerIO Lites Be. oo eee a at a (aS
SLGMALOGTAPCUS SPs"... t0ce--donibenseate toma L, |

= aT a r wre oe : 7 i

In conclusion, we wish to point out the close similarity between
Tullberg’s zonal classification of the Wenlock Shales of Southern
Sweden and the Cautley zones (see Table VI, p. 234).

234 ‘MISS G. R. WATNEY AND MISS E.G. WELCH ON THE [May rort,

(2) The Ludlow Beds.

We have been able to distinguish two zones only in the Howegill
Fells, those of Monograptus nilssont and M. leintwardinensis: the
watershed of the Howgill area is occupied by rocks which are so
unfossiliferous that the evidence obtained from that region is in-
sufficient to permit the establishment of any zone. We have,
therefore, included it in the upper part of the J/.-nilssona Zone.
It may possibly represent the J/.-scanicus and M.-tumescens Zones
found by Mrs. Shakespear in Wales and the Welsh Borderland.
It is of interest to note that JZ. bohemicus is a far more charac-
teristic fossil of the first zone than M. nilssoni. The similarity
between this area and the Lake District has already been pointed
out (p. 228).

TapLE VI.—CoRRELATION OF THE SALOPIAN Rocks.

Cautley. Welsh Borders. Southern Sweden.

Zone of Monograptus leintwardinensis.\Zone of M. leintwardinensis.

t Zone of M. tumescens
Grits and flags { P=] yar ok ee aay
5 Zone of I. scanicus.

Zone of M. nilssoni.

Zone of Monograptus nilssoni.

|-———--- --— 2 Ee ea oe

Zone of Phacops obtusicaudatus. (2)=|Zone of M. vulgaris.

Zone of Cyrtograptus lundgreni. Zone of C. landgreni. Zone of C. carruthersi.
Zone of C. vigidus. y £ Coasenad

| Zone of Cyrtograptus rigidus. Zone of C. linnarssoni. Oe Oe ae

| Zone of C. symmetricus. (|

| Zone of Monograptus riccartonensis. |Zone of M. riccartonensis. Zone of M. riceartonensis.

Zone of Cyrtograptus murchisoni. Zone of C. murchisoni. Zone of C. murchisoni.

V. PALZONTOLOGY.

Cyrroeraprus ricinus, Tullb. (figs. 2 & 38, p. 235).

Our specimens of this Cyrtograptid are intermediate in form
between C. rigidus and C. symmetricus ; we find that the branching
almost invariably occurs at the seventh or eighth theca, and that the
first nine thece are of the proximal type : these characters constitute
a slight divergence from both C. rigidus and O. symmetricus.

Several specimens show prolongation of the virgula in both
branches. It has seemed best, however, to adhere to the name
first given by Tullberg, since in general form our specimens agree

Vol. 67.] SALOPIAN ROCKS OF CAUTLEY AND RAVENSTONEDALE. 235

with the one most completely figured by him in ‘Skines Grapto-
liter’ pt. ii, 1883, pl. iv, fig. 12. Previously’ we have called
this species C. syimmetricus, Elles.

Figs, 2 & 3.—Cyrtograptus rigidus, Zullb. x 2.

2, coll. J. E. Marr ; 3, from Near Gill.]

MonoGRAPTUS WANDALENSIS, sp. nov. (fig. 4).

Polypary.—Maximum length observed = 2°50 mm.; width at
proximal extremity = 0°5 mm., increasing to a maximum of 1-5 mm.
at the distal end. Curvature dorsal, variable in amount, in some
specimens much marked at the proximal end.

Fig. 4.—Monograptus wandalensis, sp. nov.. rom Wandale Hill.
5 bes > o/ :

My NS

te *y ae at A
AY HUNG

TUR

[A= Proximal extremity, X2; B=Proximal extremity, showing part of
sicula, x 2; C=distal thece, showing growth-lines, x 5.]

Thecx.—Thirteen in 1 cm.; inclined to the axis at an angle
of 35°. The thecz show a tendency to narrow towards the aper-
ture. Apertural margin concave. Overlap of thece a half to two-

thirds of their length.
This form may be readily distinguished from all other Ludlow

* Geol. Mag. dec. 5, vol. vii (1910) p. 473.

236 MISS G. R. WATNEY AND MISS E.G. WELCH ON THE [May torr,

graptolites by the marked dorsal curvature conspicuous throughout
its length.

Locality, etc.—Wandale Hill, zone of Jf. nilssoni; associated
with J. bohemicus, IZ. nilssoni, and MW. colonus.

In conclusion, we wish to express our gratitude to Dr. Marr
for all the advice and encouragement which he has given us
throughout. We also wish to thank Prof. Charles Lapworth for
the interest which he has shown in our work; Mrs. Shakespear
for help in the identification of fossils and for the drawings of
the graptolites figured in this paper; and Miss G. L. Elles, D.Sce.,
for much help in the past.

EXPLANATION OF PLATE XII.

Geological map of the Cautley and Ravenstonedale area,
on the scale of 3 inches to the mile, or 1 : 21,120.

Discussion.

Prof. T. McKenny Huvenns thought that the Fellows of the
Society would be best able to realize the difficulties with which the
Authors had been confronted, if they were to imagine that the
Eastern Counties had been upheaved some 2000 feet, and that deep
valleys and bays and inlets had been cut through the newer rocks,
exposing the floor of older rocks below, which had been folded and
faulted and altered ; and that the parts under observation consisted
of rocks differing little in detail of lithological character through
great thicknesses, while fossils were scarce and badly preserved.
Such represented very fairly the problem which the Authors had
attempted to solve when they undertook to determine the sequence
and distinguish the zones in the Silurian rocks exposed by denu-
dation in the deep valleys cut through the Carboniferous rocks of
West Yorkshire.

Edward Forbes had explained the importance of taking repre-
sentative forms in classifying strata by their fossil contents,
pointing out that percentages of fossils in common did not furnish
a basis for correlation, unless the forms were identical or repre-
sentative—that was, if nothing but trilobites had been found in
the one, and nothing but brachiopods in the other, and there were
not a species in common, still the beds might not be remote in age.
The Authors, as might be seen in their tabular synopsis, had recog-
nized the importance of this as far as was possible in the circum-
stances, and had taken varicus species of graptolites as charac-
teristic of zones. It was obviously not a pedigree, and it remained
to be found out where the variations arose and why new forms took
the place of the old. Here again the speaker wished to call atten-
tion to the difficulties of the work. Graptolites were hard to find,
especially when the beds had been cleaved and altered, and the

sheen of rain was on the rock.

a nea

nat

ae ee

“s

-

Quart. Journ. Geol, Soc. Vol. LXVII, Pl. Xi.

LS Ca aS Seat
yy Yy ‘ll ull ail | ii 4 eee es
: Yy

alls / P) Ac qa

— EXPLANATION. —}

wv) tt . eat eae eet) ~ Recent.
" Mountaing ~ Wy Has RS 77, LJ carboniterous.

aA ae! Sry
S

riView
tou —s— D.. Zone of M, leintwardinensls.

» M.nilssoni.

==C, » © Iundgreni.

—#—C.; 1 C, rigidus.

++ C.. 1) 1 M.riccartonensis.

Wenlock Ludlow

= C, 9 » C, murchisoni,
Stockdale,
"} Coniston Limestone Series.

x
* *] Igncous Rock.

eee Linic of Fault,

Beds other than Salopian and Upper
Stockdale, and faults traversing
these, are copied from the 1 inch

Geological Suryey Map, Sheet 97 N.W.

i:

~

?
ie

{| / Les
‘all il cee / Geological Map
ji i CAUTLEY DISTRICT.
| ey “ " : ” : es wo By Miss G.R, Watney

& Miss E.G, Welch,

Unmapped Ludlow Bets

Vol. 67.| SALOPIAN ROCKS OF CAUTLEY AND RAVENSTONEDALE. 237

The index to the map began with the Coniston Limestone Series.
The speaker had cut off the upper part of this under the name of
Fairy Gill Shale, which was the equivalent of that so well described
by Dr. Marr in the adjoining Lake District as Ashgillian. There
was a troublesome fossil at this horizon, the difficulty in respect of
which Davidson left unsolved. This was Strophomena siluriana,
which had not yet been satisfactorily distinguished from the Orthis
hirnantensis of the upper or proper Hirnant Limestone, which the
speaker would regard as the equivalent of the very variable base
of the next division in the Authors’ index—namely, the Stockdale
Shale, which forms the basement-bed of the Silurian.

The Authors had attacked principally the enormous overlying
series of rocks, which, sometimes more sometimes less sandy, but
rarely justifying the name of grit, appeared to be the Northern Type
corresponding to the Wenlock and Ludlow of South Wales. They
had not here, as in the case of the Southern Type, well-marked
limestones (the Woolhope, the Wenlock, and the Aymestry Lime-
stones) to help them to run lines across an obscure country ; but, by
working out the graptolithic fauna of every available exposure,
they had succeeded in correlating the sequence with that of other
better-known areas, especially with that of Scandinavia. Such a
work required great knowledge, care, and staying power, qualities
by which the Authors had made a notable advance in geological
research. :

Dr. Marr, replying, in the absence of the Authors, remarked that
there was nothing to answer, but that he wished, as one who knew
the district, to express his satisfaction with the detailed and
accurate results obtained in an area where, owing to the some-
what monotonous uniformity of lithological characters, separation
of the zones by such characters was almost impossible until the
fossil horizons had been determined in the manner pursued by the
Authors.

238 MR. A. WADE ON THE | May rgrr,

7. Some Osservations on the Hastern Desert of Eaypr; with
ConsIDERATIONS bearing upon the Oriein of the Brrrish Tras.
By Arruur Wane, B.Sc., A.R.C.S., F.G.S. (Read March 22nd,

1911.)
[Puaves XITI-XVI.}
Conrents.
Page
Ly Inibroductrom yeas \.teeees tees ccc Salta elas ent 238
Il. The Igneous ‘ Gravels’ and Pebble-Beds_...... 238
IIT. Origin of the Igneous ‘ Gravels” ..............s... 239
LY. ithe SandyaiGwavelsy. saccclsiced.: donde eee 241
V2 Larallelcnmeiinas and Permian)... eeee caer 241
Nile, Distributionsor Pebbles: cc ctac5..4. dees sete cee 242
WET, Sands*and Maris: (.240co aes dekse: cease eee peer 244
Vili, Hifects'et Wand=blowntSand!:. 42.5.0. .0y. ae 248
1X. Orieinsothe Sang i. 20.2 nce eeemeee eee a aoe 250
Xe Salt and Gy psiimis y.-. 1... 206 -esohemencmienr ese ete 251
Xe Comparisons: oh. cess dens <5 Ooo ss cae eae eee 259
XI; Summary and Conclusions .. 21... s-cscsce esos 260

I. Inrropwucrion.
»

Durine the past two years J have on several occasions visited that
part of the Eastern Desert of Egypt which borders the Red Sea
near its junction with the Gulf of Suez. While there I made
observations of desert conditions and phenomena which appeared
to me to be of interest to the student of the conditions determining
the origin of the Triassic rocks of Britain.

A few years ago the late J. Lomas” dealt very fully with these
conditions, having made some studies of South African and Egyptian
deserts, and it is with pleasure that I find myself able to confirm
or to supplement several of the conclusions to which he came.

Il. Tue Igneous ‘Gravets’ ann PEBpie-BeEps,

The western side of the Red Sea is flanked by a wall of hills
running generally in lines parallel with the general trend of the
coast. They rise abruptly from a level or gently sloping coast-
plain, which varies in width from under | to over 10 miles. The
hills are composed chiefly of igneous rocks: red and grey granites,
dark andesites and purple porphyries, with some tracts of gneiss
and schist.

At the foot of the hills, large mounds of angular débris of the
igneous rocks occur, running in tongues from the hills out on to
the plain, or forming low foot-hills which run parallel with the

main range.

1 «Desert Conditions & the Origin of the British Trias’ Proc, Liverp.
Geol. Soc. vol. x, pt. 8 (1906--1907) pp. 172-97.

Vol. 67.] EASTERN DESERT OF EGYPT. 239

The mounds themselves consist of unsorted angular blocks and
flakes varying greatly in size, and showing as a rule no signs of
stratification where cut through. The rocks of which they are
composed are always similar to those of the igneous range nearest
to which they rest.

The mounds contain very little sand, and such as is present has
obviously been introduced by the subsequent action of wind.
Measurements taken by means of the aneroid showed that these
mounds rose abruptly from the coast-plain just below the 100-foot
contour, and that their summits, as a rule, varied in height between
120 and 160 feet above sea-level.

The mounds and ridges of igneous débris flank the eastern
slopes of the hills throughout their length; and, when viewed from
a distant position, they are seen to be remarkably even in height
and to be of the nature of a platform or terrace, broken in places
by wadis and gullies (see Pl. XIII).

In dealing with the geology of the Eastern Desert, the late Mr.
Barron remarked that
‘the plains east of the Red Sea Hills are largely formed by gravel ridges

extending from the mountains, and a of materials derived from them
or from the lower parallel ranges. ...’?

It is a remarkable fact that these ‘ gravel’ - mounds? show their
greatest development where the hills are unbroken. Wherever
gullies or wadis occur, they are either cut through or else they
are entirely absent (loc. cit.). On the south side of the Gulf of
Jemsa a large area is covered by mounds of this material, separated
from the hills by a narrow sandy depression.

III. Ortern oF THE IenzEous ‘ GRAVELS.’

In the work cited, the Egyptian Government Surveyors say very
little with regard to the origin of these mounds of ‘ gravel’ on the
eastern side of the Red-Sea Hills, although they express opinions
with regard to the igneous ‘ gravels’ that are found on the
western side of those hills and in the Nile Valley, which show
important differences and associations. *

The hills are covered with angular fragments of all sizes,
produced by the forces of disintegration common to such regions.*
The mounds in question are not, however, of the nature of screes.
‘True screes do occur on the hills, but they were not usually connected
intimately with the igneous ‘ gravels.’ As a rule, the ‘ gravels’
are separated from the hills by a narrow depression partly filled

1 T. Barron & W. F. Hume, ‘ Topography & Geology of the Eastern Desert of
Egypt: Central Portion’ Egypt. Geol. Surv. Rep. 1902, p- 126.

* The term ‘gravel’ has been used very largely, in connexion with these
beds, by Egyptian geologists. For that reason I have retained it.

3 T. Barron & W. F. Hume, op. ci/. pp. 128-30.

* See J. Walther, ‘ Das Gesetz der Wustenbildung in Gegenwart & Vorzeit’
Berlin, 1900.

Q. J. G5. No. 266. R

240 MR. A. WADE ON THE [May rorr,

with sand. Neither does it seem probable that these beds could.
have been formed as a result of the torrential rains which
sometimes occur in these hills. Such rains are very violent at
times, and the great volume of water resulting from them
produces astonishing effects in the gullies. ‘he torrents, however,
rather tend to cut through and to destroy the mounds than to
create them, and the general effect of the rains which occurred
while I was in the desert seemed to be to slope off the cliff-like
terminations of the ‘gravel’-mounds, and to distribute their
materials farther over the plains. Moreover, such action would
not easily explain the existence of the mounds which lie at some
distance from the main hills, such as those south of the Gulf of
Jemsa; nor willit account for their plateau or terrace-like characters.
Glacial action might possibly account for some of the principal
features ; but no signs of glacial action have ever been noted by
any of the travellers who have explored the hills of the Eastern
Desert.

Some clue may be obtained from a consideration of what is.
now taking place along this coast. ‘Three distinct raised beaches
are recognizable, both at Abu Sha‘ar and on the coast near Jebel
Zeit’; while a study of the islands off the coast shows that four or
even more periods of marked elevation have occurred within com-
paratively recent times. One beach, at a height of over 80 feet,
corresponds very closely with the level at which the mounds
usually begin: this is well shown at Jebel Zeit. Again, in places,
the igneous fragments are cemented together by a calcareous cement
which contains marine fossils of Pleistocene age.* Occasionally,
beds of coarse limestone are associated with them; while among
the angular fragments of the ‘ gravels,’ broken shells of recent Red-
Sea types may sometimes be found. Finally, we may note the
peculiar manner in which the plain runs right up to the base of
the [‘ gravel’ ] hills, ‘ against which it stops abruptly like a beach
against a cliff.’ °

All the foregoing observations point to the conclusion that
these beds are talus-heaps, derived from the eastern slopes of the
Red-Sea Hills by the action of the sea-waves beating against their
cliffs and slopes.

The rapid rise of this coast and the very insignificant action of
the tides in this part of the Red Sea are sufficient to explain the
absence of rounding in most localities, although this absence is not
invariable. Conditions favourable to the rounding of the pebbles
occurred in places, probably where strong currents were active.
The sharp turn in the coast at Jebel Zeit appears to have been
such a place, and beds of rounded pebbles here reach a height of
nearly 330 feet.

1 T, Barron & W. F. Hume, Egypt. Geol. Surv. Rep. 1902, pp. 123-25.
4 Thid. p, 126. * Ibid. p. 70.

Vol. 67.] EASTERN DESERT OF EGYPT, 241

LV. THe Sanpy ‘ Grave ts.’

Where the ridges and mounds touch the coast-plain, there is an
abrupt change in slope as well as a change in the formation. The
plain shelves gently off towards the sea; and, although it is covered
with loose stones and angular boulders derived from the material
of the mounds, there is a predominance of sand, which increases
seawards until nothing remains but the sands of the shore
impregnated with salt or gypsum. The ‘gravels’ in which the
sand predominates largely are very different, both in structure
and in origin, from the igneous ‘ gravels’ with which I have
just dealt. They owe their present characters largely to the action
of rain and storm waters upon the mounds of coarser material
and upon the hills themselves. They are, in fact, formed by the
overlapping of ordinary fan-taluses originating in the numerous
wadis which cut through the hills. This is beautifully shown
under the wadis cutting through the Jebel Zeit range, where these
fan-taluses reach huge dimensions and are almost perfect in their
outlines. These sandy ‘gravels’ are intersected in almost all
directions by a network of watercourses (Pl. XIV, fig. 1). There
is, of course, a distinct rise in level opposite the mouths of the
wadis—contrasting with the behaviour of the coarse ‘gravels,’
which are cut away or altogether absent.

Where the watercourses have formed a cliff like those seen some-
times in the mounds, a distinct bedded arrangement is observable,
which is never seen in the ‘ gravel’-cliffs. Such a cliff is to be seen
in the mouth of the large unnamed wadi south of the Wadi
Mellaha. The arrangement is of the nature of current-bedding ;
but this structure was shown on a large scale in shafts and
trenches made in the material of the plain itself. In these the
beds of pebbles varied greatly in thickness, from little strings of
small pebbles to coarse beds of pebbles and sand a few feet thick.
The bedding-planes were sometimes marked by a more perfect
cementation of the sand-grains, causing the lines of bedding to
stand out from the sides of the section after it had been left some
time. The sand was loose and imperfectly consolidated throughout.
The mode of origin suggested by Lomas* for some at least of the
Triassic current-bedding is here demonstrated. ‘The old channels
are filling with sand; in some cases they are completely filled, and
so, during the next rainy season, the new channels may take
courses which differ in position, in depth, or in both from those
which existed before.

VY. PARALLELS IN TRIAS AND PERMIAN.

Parallels to nearly every feature described can be seen in the
Bunter Beds. The masses of pebbles with comparatively little sand
found in the Midlands; the sand with pebble horizons sometimes
only a few inches thick, sometimes increasing to 3 or 4 feet in

1 Proc, Liverp. Geol. Soc. vol. x, pt. 3 (1906-1907) p.

75.
©

1
R2

242 MR. A. WADE ON THE EASTERN DESERT OF EGYPT. [May 1911.

thickness, common in the Bunter Pebble-Beds of Lancashire and
Cheshire ; the »ngular breccias of Hilbre Island, and so on; even
the striking eccentricity of the bedding-planes, as well as other
minor features, are all characteristic both of the Triassic pebble-
beds and of the ‘ gravels’ of the Red-Sea coasts.

The Permian conglomerates of Shropshire and South Stafford-
shire’ appear to show close resemblances with the coarse beds here
described. Calcareous conglomerates and breccias of igneous rocks,
which pass into more sandy beds, have been described; while
Prof. Hull* has expressed an opinion that these beds originated in
the very manner that I have suggested for the Red-Sea igneous
‘ gravels.’

VI. Disrripution oF PEBBLES.

Despite the fact that the conditions already described will explain
many points in Triassic geography, those observers who account
for the distribution of pebbles in the Triassic Pebble-Beds, by
transportation by means of a large river, receive some support from
a study of the ‘ gravels’ on the western side of the Red-Sea Hills.
That a river should carry stones of moderate size for a distance
of 300 miles or more has seemed to be impossible.

I have already shown that, on the eastern side of the Red-Sea
ranges, the fragments found in the ‘ gravels’ are derived from the
hills near to which they lie, and that they have travelled very
little in most cases. A similar state of things is observed in certain
localities in England, where the pebbles of the Bunter Beds can be
traced to neighbouring Mountain Limestones, cherts, sandstones,
and even veinstones. Fragments in the Permian breccias of
Staffordshire have also a local origin.

On the western side of the igneous hills of the Red-Sea coast a
different set of circumstances has affected the distribution of the
rock-fragments ; they appear to have been carried along the main
wadis and old lines of drainage, to distances which compare very
well with those to which some of the more widespread pebbles—
such as the liver-coloured quartzites—in the British Bunter Beds
may have been borne.

The distribution of these rocks from the igneous ranges of the
Red-Sea districts in the gravels of the valley of the Nile and
adjoining areas is shown very well in the accompanying sketch-
map (fig. 1, p. 243), which I have constructed from details given
by Barron & Hume.* These authors trace the pebbles from four
main centres of distribution :—

Cb) Sdiarra-didamumivanice Baeeeets ceca eee meee Granite.
(2) ii eten Gancew: Yes... 5.8 yaee. en cee eee eene See Gneiss.
(8)? slipbel AbucGaralisin “.o sees ees seen eee Schist.
(Adigets! aPICDISEEICi pet Es. iAiis. ae See ere eee ae Race Schist.

1 W. Wickham King, Q. J. G. 8. vol. lv (1899) p. 97.
2 «The Triassic & Permian Rocks of the Midland Counties of England ’
Mem. Geol. Surv. 1869, pp. 14 e segg.

3 Egypt. Geol, Surv. Rep. 1902, pp. 121 ez segq.

[ 243 J

Fig. 1.—Map of Egypt, showing the distribution of the ‘ gravels’
containing igneous rocks derived from the Red-Sea Hills.

Seale of Bnelish Miles
0 10 20 20 40 58
SS SSS SSS SSS

PORT SAID

CAIRO_

=.

-Helitan~\—” Pas
Me eS Re,

: mAs, uk
Peer
) ae Tt tee
fs
C :
SS) ( be
( yy
) ! ae
)
am ft)
oe f QI!
Say) ff
| j y
? A // /
| vy y/ ps Ce
PeeG { C
RY) ‘[~)
il as
Ne
Pf Phos
yee sda
eee 7
eu | at
boil
Tika G
} jaa!
\ 2 (|
\ \
YG
) A
pie
) bos ee
‘ Wo ie
a saree
ae See (
NS me LY: “Abu ee
‘\ s1°) 7 eter Hoaranishp
) ron ee jig sisn(Sehye wee
(Gp) TM ‘
a AN/ y ) -Meeteq
EXPLANATION: 2f/c: 2a VCE Msete
(Gs) = Gneiss. (Gn) = Granite. ead eet) oe et Ee
(A) = Andesite. (Sch) = Schist. : | oh et arts ~
309° *: Igneous Gravels. —~ nD aheer

ees

244 MR. A. WADE ON THE [May 1911,

The pebbles have travelled in more or less westerly directions
down the wadis, into the important north-and-south wadi which
continues the line of the Nile north from Qena. ‘They are
abundant for some distance to the north and south of Qena.
Thence they have been carried northwards down the Nile Valley.
They were found by Mr. Beadnell* on the western side of the Nile,
this fact having been used in the determination of the age of that
river. The most interesting occurrences of these rocks, which the
Survey geologists say ‘could only come from the Red Sea’,* are
at Heluan, a few miles south of Cairo, where they were noted by
Mr. Beadnell, and in the Delta itself, where they were found in
the Royal Society’s boring at Zagazig.» Thus these rocks have
been river-borne for at least 400 miles.

A careful examination of the Jubal and Gaysum groups of
islands showed that these ‘gravels’ do not exist upon them.
This suggests that these islands have come into existence since
Pleistocene times, the age generally assigned to the ‘ gravels.’

A very thin bed of ‘ gravel,’ containing pebbles of igneous rocks,
does occur beneath the Upper White Limestone Series on Jubal
Island. The pebbles are evidently derived from the igneous rocks
of the mainland, and consist of pink granite, felsite, andesites, and
porphyries. Since the age of the limestone ranges perhaps from
Upper Miocene to Pleistocene, the presence of this gravel suggests
a local extension of the land-area at some time immediately prior
to those periods. This has an important bearing upon the sequel.

VII. Sanps anp Marts.

The Gulf of Suez, with its parallel ranges of hills, appears to act
as a funnel down which cooled air from the north is drawn towards
the Equator. Thus there is an almost constant northerly wind,
which frequently blows with violence.

Zeit Bay and the Gulf of Jemsa are both directly in continuation
of sandy tracts of country, from which there is a continuous passage
of dust and sand. Both are at certain seasons bordered with
saline mud containing very much fine material, along with some
coarser sand-grains.. The passage of the dust must be checked
by the water of these bays, and the fine mud is the result of the
accumulation which necessarily takes place under these conditions.
Here, then, we have in actual progress the state of things adduced
theoretically by Mr. H. C. Beasley ’ to account for the Keuper Marls
(so-called) of South Lancashire and Cheshire. In these districts

1 J. W. Dawson, ‘Notes on the Geology of the Nile Valley’ Geol. Mag.
dec. 3, vol. i (1884) p. 289; see also T. Barron & W. F. Hume, Egypt. Geol.
Surv. Rep. 1902, p. 121.

2 T. Barron & W. F. Hume, op. cit. p. 128.

3 J. W. Judd, ‘Second Report on a Series of Specimens of the Deposits of
the Nile Delta’ Proc. Roy. Soc. vol. lxi (1897) p. 382.

4 T. Barron & W. F. Hume, op. cit. pp. 78 & 79.

° Proc. Liverp. Geol. Soc. vol. x, pt. 2 (1905-1906) pp. 79 et segg.

Vol. 67.] EASTERN DESERT OF EGYPT. 245

these fine deposits are not of the nature of true marls, but consist
largely of very fine particles of comminuted quartz,’ such as cer-
tainly form the bulk of desert-dust. ‘he great thickness of the
Keuper Marls in Cheshire no longer surprises us, when we see how
persistently the dust is at present being blown from the Eastern
Desert towards the bays of the Red Sea. The conditions in that
sea are not, however, favourable to the accumulation of such thick
deposits: for a rapid rising of the sea-bed is in progress, instead of
a sinking, which would be necessary for the purpose.

It is probable that true marls are in process of formation beneath
the waters of these bays, just as true marls are found in the Keuper
beds in other parts of Engiand. In fact, true marls were found in
borings north of the Gulf of Jemsa, as well as among the recently
raised limestones on Jubal Island. The materials for the formation
of the dolomite crystals observed by Dr. Cullis? in the Keuper
Marls of the Midland and South-Western districts are present |
in these muds, since analysis* revealed the presence of calcium
and magnesium salts in their cementing-materials. A careful
search for these rhombs was made in the marls—both among those
recently elevated on Jubal Island, and among those which are at
present forming on the coasts of the Gulf of Jemsa. The material
was first allowed to stand in water for 24 hours: the liquid being
repeatedly changed, in order to get rid of the soluble salts. In the
fine residue of the marls from Jubal Island, myriads of these tiny
rhombs were discovered. They were compared, through the kindness
of Dr. Cullis, with those found by him in the Keuper Marls. They
were undoubtedly similar in shape and other properties, though
somewhat smaller in size. The material from the coast of the
Gulf of Jemsa was not so satisfactory, though here again the crystals
were present, if in smaller numbers. ‘This interesting discovery of
dolomite-rhombs, for the first time in recent deposits under desert
conditious, goes far to support the contention of Dr. Cullis that
the rhombs in the Keuper Marls were formed by actual deposition
from supersaturated waters; it also furnishes a further interesting
parallel between the conditions of deposit in the Triassic sea and
those which obtain in the present Red-Sea area. The results of
this investigation are important: they tend to show that, although
the Keuper Maris of the Midlands and the West of England were
laid down under aqueous conditions, those of the Lancashire and
Cheshire areas were laid down nearer to terrestrial conditions, the
land probably consisting of low-lying areas bordering inland seas
or saline lagoons,

The saline mud on the shores of the Gulf of Jemsa is mostly
consolidated, and consists of a hard deposit cemented by means of
soluble salts (see p. 252) which are present in a crystalline form.
A certain amount of the cementing-material has been re-dissolved,
leaving cavities and a honeycomb structure in places. The broken

‘ P. Holland & E. Dickson, Proc. Liverp. Geol. Soc. vol. vii (1896-97) p. 443.

? Rep. Brit. Assoc. 1907 (Leicester) p. 507.

5 Tabulated later, p. 252.

246° MR. A. WADE ON THE [May 1911,

material at times shows excellent cubes of salt under the micro-
scope, and many of the hollows appear to have cube-like forms.
Footprints, sun-cracks, and wind-ripples impart a Triassic aspect to

the sands in places, especially where large sea-birds have left their
tracks.

Fig. 2.—Sand with ‘ dreikanter, from the sandy gravel-plains north
of the Gulf of Jemsa. (Natural size.)

Many of the gullies are being filled with sand, and one can easily
recognize the sifting effect of the wind. The particles of sand in
the deposit at the foot of a gully are much coarser than at the
head, and contain numerous flakes of granite and andesite derived
from the neighbouring rocks. Here the sand is rather firm: as

Vol. 67.] EASTERN DESERT OF EGYPT. 247

one climbs the gully, the sand becomes finer and less firm, until it
is so fine and loose tkat one sinks up to the knees in it. ‘The equi-
librium of the mass is very unstable, the slightest jarring causing
great masses to slide much like a fluid towards the bottom.

Fig. 3.—loraminiferul sand, with abundance of Orbitolites com-

planata Lam. and other organisms. Southern shore of South
Gaysum Island. (Natural size.)

The sands which occur among the gravels in the depression
between the Zeit range and the Um-Esh range are of a peculiar
character. Very little fine sand occurs, but grains as large as
peas, usually 5 to 10 millimetres in diameter, cover large areas
in such a manner as to appear as though they had been artificially
set. A careful examination of the individual grains showed that

248 MR. A. WADE ON THE [May 1911,

they consisted of almost every type of local rock, quartz-grains
slightly predominating. They were all polished and worn, and very
frequently facetted so as to form tiny dreikanter (fig. 2, p. 246, &
Pl. XV, fig. 1). Dreikanter on so small a scale do not appear to
have been previously noted. These large grains are not often carried
into the air by the wind; but, when the wind is sufficiently strong,
the effect of such flying grains 1s painful in the extreme, and it is
impossible to face them for any length of time. ‘This type of sand
owes its character to the sifting action of the wind: the fine sand
has all been removed, and is often found filling gullies high up
in the hills. It leaves behind these bigger and heavier grains,
which are just able to withstand the ordinary force of the wind.

On the islands no siliceous sand is to be found, as a rule. ‘The
sands are calcareous, and are chiefly formed from comminuted frag-
ments of corals and shells, as on Jubal Seria; of calcareous alga, as
on the northern side of Gaysum Island; or of foraminifera, as. on
the southern side of Gaysum Island (fig. 3, p. 247), where Orbitolrtes
complanata is the predominant form.

VIIL. Errrecrs or Winb-BLOWN SAND.

The action of the wind upon the various rocks was very striking.
The softer limestones are sometimes worn into fantastic shapes
(Pl. XIV, fig. 2); and sometimes they are regularly grooved in such
a manner as often to simulate bedding-planes. The effect of the
sand-blast upon soft limestone is nowhere more magnificently
shown than on Jubal Island, although the sand there is soft and
calcareous. In the limestone-cliffs occur cirques or semicircular
bay-like openings, which go far inland, leaving hard outliers, carved
into curious shapes, standing near the shore. They vary greatly in
width, but are sometimes over 100 yards across. On the sides of
these cliffs the fossils stand out in relief, and sometimes present
the only means of determining the angle and direction of dip in the
massive beds. Similar cirques are described by Barron & Hume! on
the western side of the limestone outlier of Abu Had: they explain
the origin of such cirques as due to the widening of joint- and fault-
planes by the sand (PI. XV, fig. 2). Afterwards the sand-eddies
scoop out the hollows thus formed, until wide semicircular recesses
are finally formed in the cliffs. On Jubal Island, however, these
cirques are connected with raised-beach phenomena, and are cer-
tainly of marine origin in their early stages.

The effect of the wind-blown sand upon the harder rocks is some-
what different. Thechief action of the sand-blast upon the granite
is to assist in the removal of the felspar-crystals from the surface
of the rock : these crystals become weakened along the planes of
cleavage by the constant expansion and contraction due to the heat
of thesun. The outer layers are more affected than the deeper-lying
layers, and hence the tendency to flake off at the surface. The
quartz stands out in relief all over the surface of the granite, but
it soon becomes dislodged in the general break-up of the felspathic

1 Op. cit. Egypt. Geol. Surv. Rep. 1902, p. 289.

1

Vol. 67.) EASTERN DESERT OF EGYPT. 249

constituents. A specimen of the granite-surface which | obtained
shows this action in a remarkable manner, the quartz - grains
standing out in high relief, and the felspars being almost entirely
eaten away. ‘The flying sand-grains have been driven on to the
softer portions of the rock with such violence, that they are to be
seen still wedged firmly into every crevice (see Pl. XVI, fig. 1).

This, however, is not the only way in which the sand assists
in the disintegration of the igneous rocks. ‘There is still another
phenomenon, which does not appear to have been noted hitherto.
The very finest material is forced into the tiniest cracks and crevices
in the rocks. Rocks, which at first sight appear to be quite sound,
crumble to pieces when struck by the hammer, and all along the
shatter-planes will be found this very fine sand penetrating to
considerable depths. Here it tends to assist the other agents of
disintegration : the action of frost, the alternations of heat and cold,
the percolation of moisture, and more rarely the vital forces due
to the action of plants and animals. The grains act as tiny wedges,
slipping ever farther into the cracks when opportunities occur, until
finally the parts are so forced asunder that the rock falls to pieces.

The andesites and porphyries become more polished and grooved
than the granites, and show less tendency to crumble. They also
are more liable to develop facets where the blowing sand-grains
have planed off corners and edges. Sometimes these rocks are
grooved all over in a peculiar manner by the action of the wind-
blown sand, and resemble exactly the specimens obtained by Prof.
Watts’ from the Triassic rocks of the Charnwood-Forest area. In
some specimens, hard zeolites have resisted the action of the wind
aud stand out all over the surface, capping curious protuberances
which look very like collar-studs.*

One of the most interesting results of the action of wind-blown
sand was observed on Jubal Island. This was the mechanical
etching of the crystalline gypsum (selenite) which occurs there. The
calcareous sand wears away the faces of the crystals, but its action
is selective. The greatest wearing effect seems to be produced in
directions parallel to the orthopinacoid (1.0.0.) and the negative
hemipyramid (1.1.1.). The result is a beautiful series of etched
figures produced mechanically, covering the clinopinacoidal faces of
the mineral (see Pl. AVI, fiz. 2).

Other phenomena, due to wind- blown sand, such as the formation
of dreikanter, have been dealt with elsewhere.* The action of
the sun upon the flints and cherts derived from the Eocene lime-
stones is worthy of note. The surfaces of such flints are usually
chipped all over, owing to small fragments having broken off with
a conchoidal fracture, and sometimes the fracture has left perfect
cones on the surfaces. In such cases, the angle of slope of the cone
was usually found to lie between 30° and 35°.

. W. W. Watts, Rep. Brit. Assoc. 1899 (Dover) p. 747.
* Mr. T. O. Bosworth has also used this simile, in describing comparable
occurrences on the coast of Mull, Geol. Mag. dee. 5, vol. vii (1910) p. 354.
3 Geol. Mag. dec. 5, vol. vii (1910) p- 394.

250 MR. A, WADE ON THE [May roi,

IX. ORIGIN OF THE SAND.

With a view to discovery, if possible, of some clue to the origin
of the sand on the desert and in the hills, I examined a series of
samples from various localities. One series was especially collected
from the shore, one from the centre of the plain, and one from the
gullies in the hills.

Prof. Walther,’ in his work on the physiography of this desert,
says that the chief source of the sand is the granite area. Barron
& Hume’ disagree with this, and claim the Nubian-Sandstone areas
as the source of origin. They do this, not on account of the
mineral composition of the sand, but because of the abundance of
sand in those areas and its absence in the midst of the granite
hills. They specifically mention the tract that I examined in detail,
as being one towards which the sand is being continually blown
from a Nubian-Saudstone area. This may account for some part of
the sand present along the eastern side of the Mellaha-Ksh ranges,
but the microscope does not, in the main, support their contentions :
it rather justifies, indeed, Prof. Walther’s statement. I append the
results of microscopic examination of four samples of sand, the last
of which was taken from the base of a Nubian-Sandstone escarpment.

No. 1 Sample.—Salt-caked sand from the western shore of the Gulf of
Jemsa, consisting of large rounded grains mingled with very fine
particles of dust, made up chiefly of fairly angular quartzose material.
The large grains are well rounded, and include quartz, pink felspar,
some cream-coloured felspar, and a little green epidote. Flakes of
biotite are common: they are somewhat altered, and present a very
metallic appearance. More angular grains or tiny flakes of a black rock,
resembling the dark andesitic rock of the hills nearest the shore, and
one or two subangular fragments of a purplish-brown rock were present.
A few tiny needles, probably of apatite, occur also, as well as some
tiny rhombs showing a faint high refractive index and assuredly not of
an isotropic mineral. These latter are almost certainly dolomite. The
biggest grains observed had a diameter of 2°5 mm., though 1:5 mm. was
a more usual size.

Foraminifera are fairly plentiful, forms apparently assignable to
Rotalia and Textularia being discernible. :

No. 2 Sample.—Loose sand filling a watercourse, half a mile from the shore.

This sand was much finer throughout than that of Sample 1. The

same abundance of well-rounded pink felspar is present, with much

colourless quartz. Very many dark and even black grains are present,

some of which are slightly magnetic. An altered brassy-looking mica
occurs here in tiny flakes.

No. 3 Sample.—Obtained near the foot of a gully in the hills, about a mile
west of the Gulf of Jemsa.

Here the grains vary greatly insize. ‘They range in diameter between
0°75 mm. and the finest dust. The sand contains all the minerals
observed in Samples 1 & 2, together with small angular flakes of the
black rock measuring up to 1 em. in diameter. Here, again, the pink

1 ‘Ueber Ergebnisse einer Forschungsreise auf der Sinaihalbinsel & in der
Arabischen Wiiste’ Verhandl. Gesellsch. f. Erdkunde Berlin, vol. xv (1888)
Daas:

2 Op. cit. Egypt. Geol. Surv. Rep. 1902, p. 288.

Vol. 67.] EASTERN DESERL OF EGYPT. 251

felspars are among the best rounded of the grains, while the black grains
are very angular. Wind-carried foraminifera are present in this sand.

On treating the sand with acid, I found that some calcareous particles
are present. I also found in this sand some purple grains, which are
probably derived from the porphyries of the Mellaha range.

No. 4 Sumple.—Sand from the base of the Nubian-Sandstone escarpment,
Zeit range.

This sand consists almost entirely of colourless quartz-grains. Some
cloudy grains occur, which probably are milky quartz. A few grains of
somewhat altered mica are seen. ‘The sand is more purely quartzose
than any of the other samples. The grains are rounded to subangular,
and are fairly even in size.

A noteworthy feature is the way in which the felspars are
rounded into sand-grains. The dry disintegration seems to result
in very little chemical alteration, the effect being almost entirely
physical. Asa result, felspar is a common constituent of these sands.

I have already shown that the big sand-grains found in the
desert between the Um-Esh and the Zeit ranges are derived from
every type of local rock, and are intimately connected with the
‘gravels’ in composition and in origin.

It thus appears that the sands along this belt, at any rate, are
in the main derived from the break-up of the local rocks: including
chiefly the granite, and to a smaller extent the andesitic rocks and
porphyries. The granite, where exposed, can be seen in all stages
of decay. Instead of breaking down into flakes, it erumbles away
into coarse material, which is readily picked up by the strong winds
and soon worn down into sand-grains. It is certain, however,
that the Nubian Sandstone does supply some part of the material,
although it does not appear that such material predominates.

X. Satr anp Gypsum.

In studying these deposits, it is best to deal with them under
two heads :-—

(a) The deposits now in process of formation.

(b) The older deposits, such as are found in borings or in outcrops at
the surface.

(a) The first type of salt-deposit was best seen in process of
formation on the western side of the Gulf of Jemsa. At this place
the gulf is bordered by a shallow depression, very little above the
highest tides that we observed. ‘The depression runs in a series of
crescentic outlines for a considerable distance along the coast. It
is filled with a deposit of snow-white salt crystals to a thickness
in places exceeding | inch. This deposit was evidently due to
the evaporation of sea-water which had at some time flowed into
it during a higher tide than usual, or had been driven into it by
a favourable wind. The hardened saline mud found along the
borders of the gulf, and also at the southern end of Zeit Bay, has
already been described (p. 245). This occurrence reminds one of
the similar phenomena noted in the Keuper Marls of the Lancashire

252 MR. A. WADE ON THE | May rort,

and Cheshire districts. It may be that the presence of the salt
is not entirely due to the evaporation of a sea-water film. All
along the edge of the sea was a white spume which accumulated
continuously from the air-bubbles left behind by retreating waves.
This frothy material was intensely salt. After standing some time,
the water partly evaporated, leaving behind a more saline and sticky
white mass, which was constantly being blown inland over the
sand. In this manner enormous quantities of salt must be carried
inland, and deposited among the sands of the desert. Sometimes
stones were found at some distance from the sea, coated with a pure
white encrustation of salt: in these cases the salt had evidently
been carried inland by the wind. On the northern coast of Gaysum
Island several patches of snow-white salt crystals, perfectly formed
and frequently measuring 5 to 10 mm. in diameter, are to be seen
at a height of 20 to 30 feet above sea-level. Here, again, the
salt was carried in as foam. Saline encrustations were found on
the fossils of the raised coral-reefs of the Jubal group of islands,
almost 200 feet above sea-level.

I append analyses made of the saline sand from the. shores of
the Gulf of Jemsa. (The spectroscope revealed the presence of
abundant sodium with some calcium. Potassium was faintly
indicated.)

Sanple No, 1. Sample No. 2.

I. Bulk Analysis. Percent. I. Bulk Analysis. Per cent.
Na Ok(with some KOO) O02 (os ons aciane cies ne eee a eee 23°40
CAO el aaic eee oie again nacivgenevaement Copco 5:14
Mie) Stic ated 2 oe Sone 2 nee ree Breen es escds cocci: 1-42
RG sOls tee} Sevens neces noes DAO bie Alea. neddeistedatdie see eop eee onee 9:90
Si@ east ceeen oeeaeaes BoAO i! lusehaeaek dies Senta eee mee 23°78
Clic Ree ee teenies QS D2; axuniioapiinatie ene tomcteseeeeaece nae 30°80
S\O)s ndcooscuBeados soontagsoo AGSD WV Aadebaolats Haletitts slat dels eee Nene 4°52
(Ol OR ae cernsncnasoncdic-occn a BaD capeeaeies sctsnees-testhiedesoneeee amEEES
LE WUE seen ere no ncuet WTA 1 ics cl ORS URIS R aeraa ee 6°76

RG GAS# sees ee. 103°75 105°72
1b II. Water extract.
Matter removed by solution CaO) 2 eee 2-14
in warm dilute HCl... 61°91 Na.Oiscstesdts-cereee 23°40
Residue insoluble in dilute Olathe. ee eee 30°80
JET ONS sabacteocodose nee 34°20 MeOvica. aie trace
BAe a clate ois 1:74
Ch ween 510 Acid extract,
; mee SiON). Oa ae 23-78
MNotallameeae neat 100°95 CaO Riese 3°00
= Fev Ou cass. ohare 9:90
MeO pecclieton gate 1-42
SOs ttc een cates 4°42

[The results total more than 100 per cent., because the sodium is returned as
oxide. The amount of sodium in Sample 2 is equivalent to 26:50 per cent.
of sodium chloride, and the calcium oxide in the soluble portion is equivalent
to 4°25 per cent. of calcium chloride. |
ee

1 See J. G. Goodchild, ‘Desert Conditions in Britain’ Trans. Geol. Soe,
Glasgow, vol. xi (1897-1900) p. 85.

Vol. 67.| EASTERN DESERT OF EGYPT, 255

The foregoing analyses show that only about a third of the rock
consists of sand, the remaining two-thirds consisting of soluble salts.
A fair amount of gypsum and magnesium salts is indicated along
with the rock-salt in the deposits, as would have been expected in
the circumstances.

Both the Gulf of Jemsa and Zeit Bay are continuations of low
tracts of sandy and gravelly desert which lie to the north of them.
Where these tracts meet the sea there salt marshes exist.. In
examining the country at the head of the Gulf of Jemsa, I found
that the marsh gradually gave place to firm ground as one pro-
ceeded landwards. But another change took place: the cementing-
material was now gypsum and not salt. ‘The desert was curiously
marked by low concentric ridges only an inch or two high, which
ran somewhat parallel to the shore-line, as well as to the borders
of higher tracts of ground; they suggested lines left by the
gradual desiccation of a shallow pool of water. The ridges were
covered with aggregates of gypsum crystals, some of which
reached 5 or 6 centimetres in length. When the ground was dug
into, it was found to be very moist underneath. A little farther
north the sandy desert presented a curious appearance, being
covered with a network of projecting veins of gypsum. These stood
out sometimes 6 inches or more from the surface, owing to the fact
that they seem to resist the wind—the sand in between the veins
haying been removed by that agency. Similar veins are sometimes
very abundant in the recent limestone of the Gaysum Islands.

Again, on South Gaysum Island, the surface in the centre of

the southern part of the island was found to consist entirely of

eypsum crystals. When the deposit was dug into, the gypsum was
found to be present in stout fibrous crystals closely packed together,
which penetrated from 6 to 12 inches or more below the surface.
When traced in any direction, the gypsum deposit was seen to
merge insensibly into raised coral-beach or shelly and foramini-
feral sands. The deposit itself contained practically no organic
remains; it 1s evidently in process of formation, at the expense of
the more normal deposits. It appears, then, that both here and at
the head of the Gulf of Jemsa and of Zeit Bay the sea-water is
being drawn up by capillarity into the huge deposits of fine sand
which there exist. The gypsum seems to be deposited there by
this action, the salt probably being retained in solution. Where
the sands are siliceous, the result is the formation of gypsum crystals
among the sand at the surface. Where the sands are calcareous,
the change seems to be accompanied by a metasomatic replacement
in the caleareous matter, resulting in the destruction of organic
remains. That the shells of the raised coral-recfs do tend to become
converted into gypsum was proved by an analysis of a shell taken
from the raised reef of Jubal Seria. This yielded the following
result :—
Per cent.

CACO Meares sis sve nees about 60
Ca I tae d sc ddacceiscace 20

Other salts, chiefly sodium chloride 20
and salts of magnesium male

eee eeeee

254 MR. A. WADE ON THE EASTERN DESERT OF EGYPT, [May 1gtt.

An analysis of the ‘gypsumized’ beds of South Gaysum Island
gave the following result :—

Per cent.

CaO! 6, Fee 30°20
SIO, ccna teckemeeseue 2-14
Na,O 3S ne ere ESS)
COs | ata teas aeece 1-72
SO, ik rarer at aaas 39°38
EO aie biteetacet 21°50
Gl ae sc eee ee 2:69

(Lotalicsenctescuie 99:98

If it be held as proved that these raised calcareous beds are thus
altered under suitable conditions into gypsum, some difficulties con-
nected with Triassic and more recent Kgyptian geology are evidently
nearer solution.

A certain amount of encrustation, consisting of soluble salts,
occurs upon almost every fossil present on the islands in the Red
Sea. In order to determine its character, I carefully removed the
encrusting salt from the fossils that I had collected, and subjected
it to analysis. The mean of four analyses on the very small quantity
available was as follows :—

Per cent.

OE Op 4s ae tS ei 28°78
sk Or ah certo sane ane 648
Dy Oy can anne aes nem 18:10
MICO wate eae ek ei ates 2:27
COS ie eects 3141
SOE Wieser es... UAT
Ol” 1a AES. Oh 8:92
TO) peaks gee deus 1:45

otal ic ioc 100:12

The solution gave a distinctly alkaline reaction.

There was some considerable variation in the amount of chloride,
sulphate, and silica present. Roughly speaking, the analysis indi-
cates the presence of about 50 per cent. of CaCO,; 7 of MgSO, ; 14
of NaCl; and 18 per cent. of Na,CO,.

The presence of sodium carbonate is interesting, and suggests
mass action between the salt and the limestone }:—

CaCo,+2NaCl — ~*~ CaCl,-+Na,CO,.

—=iw—_____

1C. M. Guldberg & P. Waage, ‘ Ueber die chemische Affinitat’ Journ.
Prakt. Chem. vol. xix (1879) p. 69. Since the above was written, Mr. S. R.
Illingworth has drawn my attention to the fact that Berthollet has shown
that this reaction does take place on the shores of certain Jakes in Egypt: see
G. Senter, ‘ Outlines of Physical Chemistry ’ London, 1909, p. 199.

[ 255 ]

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Q.J.G.8. No. 266.

‘naam nog pag ayn fo jund fo dnu-ynays jnohor0a9— "fp “Sy

a PS or

256 MR. A. WADE ON THE [May tg1r,

Calcium chloride was proved to be present in the limestone bearing
the encrustations, and these were accompanied by the presence
of fine transparent needles of very small size. The needles in-
creased in quantity after specimens had been kept for a time, and
were evidently a kind of efflorescence. They have low refractive
index and bi-refringence, and give straight extinction. Analysis
proved them to be the mineral epsomite (MgSO,7H,0).

(4) Dealing now with the second type of gypsum and salt deposit,
we are at once confronted with an attractive but somewhat difficult
problem. An enormous series of gypsum and anhydrite deposits is
present in the area which we are considering. They form beds
hundreds of feet thick on the Jemsa peninsula, in the Zeit range,
and elsewhere, localities not previously noted being the centre of
Jubal Island and the northern end of Shadwan Island (see map,
fig. 4, p. 255).

The beds of anhydrite are sometimes peculiar. The mineral
oceurs as a soft chalky-looking substance with a radiate structure.
It looks as though the mineral had been formed from a bed of
gypsum in which the crystals were present in radiating aggregates,
resembling a spherulitic structure on a fairly large scale. An
analysis of this anhydrite gave the following result :—

Per cent.
CaO cee eee 38°70
MO Reet edaciacsies « 2:08
SO greece: ae gece 59°30
NalO and OF Sr... se. trace
0s WO eee oa ene 0-12
Totalltee. so ckens 100°20

Barron & Hume’ consider that these deposits represent ‘ gyp-
sumized’ limestones of the Eocene and Cretaceous formations. They
are of opinion that the change has taken place from above, by the
introduction. of sulphuretted hydrogen due to the decay of organic
matter in the raised-beach deposits with which these beds are
often associated.

L. H. Mitchell, on the other hand, connected the change with
the igneous intrusions; and the close connexion between the beds
of gypsum and the veins of sulphur formerly worked at Ras Jemsa
would support his opinion. Moreover, hot water has been struck
in two or three localities in course of the search for oil: this also
could perhaps have played a part. Mitchell was of opinion that the
granites of Jebel Zeit were intrusive into the overlying limestone
series, but this is not confirmed by later studies of the locality.

1 Op. cit. Hgypt. Geol. Surv. Rep. 1902, pp. 192-97.
2 «Ras Gemsah & Gebel Zeit: Report on their Geology & Petroleum ”
[Eeypt. Govt. Rep.| Cairo, 1887.

bo

Vol. 67.| FASTERN DESERT OF EGYPT. dT

Now, although I have shown that the alteration of limestone to
gypsum is proceeding at present in certain areas, there are many
reasons for doubting the conclusions of the Survey geologists. In
the first place, the gypseous series is of enormous thickness : reaching
several hundreds of feet in the Zeit range, of almost pure white
saccharoidal gypsum with beds of pale-blue anhydrite, and a variety
which is pure white. The beds are in places both overlain and
underlain by unaltered limestones, a fact which appears to be fatal
both to the Survey theory and to Mitchell’s older theory. The
best evidence comes from recent borings.

Borings for oil throughout this region pass through a great series
of beds consisting of gypsum, rock-salt, thin dolomitic limestones,
and marls. AtJemsa and on Jubal Island the gypsum deposits are
of great thickness, and the dolomitic beds are well developed; but
the rock-salt is not so abundant. JBorings to the north of these
localities meet with converse conditions. The rock-salt with
marly partings is most abundant, while the gypsum and dolomitic
limestone are more rarely-present as partings. It can be shown
that there is some transition from one state of things to the
other.

If we take the Ashrafi reef as centre and the southern ex-
tremity of the Jemsa peninsula as radius, and describe a circle, all
borings near the centre of the circle pass through the rock-salt
phase, while the borings on the rim of the circle pass through the
gypsum-dolomite phase. At one or two horizons beach-deposits
occur, With some sand and pebbly gravel: these suggest temporary
encroachments of terrestrial conditions. This association and this
distribution of beds seem to prove almost beyond doubt that the
great gypseous series is an original deposit. The finding of fish-
scales in the marly beds at the base of the gypsum series by Mr. J.
Wells, and perfect fish-remains in marly partings higher in the
series by Mr. C. Sara, sets the matter, however, beyond question.

The area in which the beds are found was evidently a Jand-
locked basin that had no communication with the sea. The position
of the salt-deposits with regard to the main gypsum-deposits is just
what one would expect from a theoretical consideration of such
conditions, and would not be likely to occur if the beds had originated
by subsequent alteration.

Similar occurrences of salt, gypsum, and dolomite occur in many
parts of America, chiefly in Texas and California. They have been
fully dealt with by the geologists of the United States Survey.’
Some of the gypsum of the Zeit range and elsewhere along the
coast appears to be, in places, a secondary product derived from the
principal beds by the action of rain and storm-waters, and re-formed
on the plains. The wadis cutting through the gypseous series are
invariably narrow and tortuous gorges with perpendicular walls.
Where they debouch upon the plains there is a soft, white, ashy deposit,

1 Bull. U.S. Geol. Surv. Nos. 218, 223, 225, 260, 285, 315, 364, ete.
s 2?

_

258 / MR, A. WADE ON THE [May 1911,

stained brown or grey at the surface, and weathered into curious
horny protuberances. This is called by American writers gypsite,’
and is actually composed of an aggregate of crystalline plates of
gypsum of microscopic size.

The remarkable effect of warm sea-water upon the gypsum was
pointed out to me by Mr. Wells; and an experiment was carried out
by Mr. Sara and myself, in order to obtain some idea of the
solubility of the gypsum in such circumstances. Two masses of
gypsum were treated :—

No. 1. A mass of 107 lbs. lost 52 Ibs. in 5 days,
No. Di 3h Wa 7¢ ” Bie ” 3 ”

The loss per day in both cases was approximately 10 per cent., a
result which explains some physical features connected with the
outcrops of the massive gypseous series.

The common association of petroleum, sulphur, gypsum, and
rock-salt found in many parts of the world, as well as in the Red-
Sea area, is critically discussed by G. J. Adams? in an able
manner, though without very definite conclusions, since our know-
ledge of the facts is not yet sufficient.

The age of the gypseous series is difficult to determine, owing to
the lack of fossils, though a few imperfect specimens have recently
been found in the upper beds. The beds are seen to underlie
white hmestone of Pliocene or late Miocene age, especially on
Jubal Island, where the junction is unconformable: a conglo-
merate marks the break. They rest upon beds of Kocene age at
more than one locality in the Zeit and Um-Hsh ranges. It thus
appears that the gypseous series dates from some part of the
Oligocene and Miocene Periods: it is certain that during that time
continental conditions prevailed in Egypt.

Very few deposits which tend to bridge the gap between the
Eocene and the Miocene have yet been discovered. Those of the
Fayum in the Western Desert are well known, while these products
of the evaporation of a salt-lake or series of salt-lakes which I have
been describing may well be their contemporaries in the Hastern
Desert. It is significant to note that the very similar gypsum-
deposits which exist in Cyprus have also been assigned to the
Oligocene Period.*

1 F. L. Hess, ‘A Reconnaissance of the Gypsum Deposits of California ’
Bull. U.S. Geol. Surv. 413 (1910) pp. 7 e¢ seqq.

? Bull. U.S. Geol. Surv. 184 (1901) p. 49.

3 C. V. Bellamy & A. J. Jukes-Browne, ‘ The Geology of Cyprus’ Plymouth,
1905, pp. 22, 25.

Vol. 67.] EASTERN DESERT OF EGYPT. 259

XI. CompaRIsons.

The significance of these beds, both of salt and of gypsum, will not
be lost upon the student of the Triassic rocks of Britain. The beds
in the Red-Sea area are comparable in every way with those of the
Keuper, although the great salt-masses in the Keuper are probably
not comparable in thickness with those now described.

The coasts of the Red Sea are at present rising with what

appears to be unusual rapidity, geologically speaking. If continued,

this will entail a severance of the connexion with the Indian Ocean,
and it seemed to me to be useful to endeavour to calculate the
thickness of salt which would result from the desiccation that
might ensue.

Taking the average depth of the Red Sea from the Admiralty
Charts to be 2400 feet (probably a low estimate), the amount
of salts dissolved in the sea as about 4 per cent., and their density
2-00,' I reckon that the thickness of such a bed of salt would be
50 feet. It would certainly be somewhat greater than this, because
of certain obvious corrections that would need to be applied.

Now, this proves that the beds actually present could not have
been formed by the desiccation of a sea having the salinity of the
present Red Sea, unless that sea in the process of drying up shrank
greatly in size and concentrated its salts over a limited area.
Occasional additions of salt water by temporary inroads from the
ocean will not explain matters, since such connexion with the
ocean would in all probability have been accompanied by other
phenomena, of which there is no evidence. Incursions of. sea~
water do seem to have occurred towards the end of the period, and
are suggested by the alternating deposits of salt and gypsum, which
appear to be somewhat late in age, and seem to occur only in the
central parts of the area.

If we assume that the Keuper Sea was similar in depth to the
Red Sea, we reach a similar conclusion, for beds of salt 100 feet
thick are to be found in that formation. If, as seems more likely,
we assume that the Keuper Sea was shallower, it is clear that its
waters were vastly more saline than the waters of the present
ocean. Now, since we have no reason to believe that the ocean
was at any time much more saline than at present, it follows that
the Keuper salt-beds were deposited in an inland sea uncon-
nected with the ocean, since we know that where such seas are in
continuous connexion with the ocean at the present day, there is
little difference in the salinity.

There is, however, one strong contrast. Whereas, as Mr. A. R.
Horwood has recently observed, there is a tendency for the higher
beds to overlap the lower in Triassic times, a tendency due to
general subsidence, the reverse is the case in the Red-Sea area.
The lowest beds here tend to have the greatest extension, owing to
the fact that this area is one that is rising. Hence the beds which
would correspond with the Keuper Series occupy the smallest area,
occurring in hollows in the older rocks.

' J. H. Howell, in J. B. Skertchley’s ‘ Physical Geography ’ (31st ed.) 1896.

260 MR. A. WADE ON THE . [May tort,

XII. Summary anp Concrusion.

The results of the investigation are briefly as follows :—The
‘ gravels’ of the Kastern Ranges are of local origin, accumulated by
the sea under peculiar local conditions. ‘The desert sands in the
area are mostly derived.from rocks in their immediate vicinity.

Dolomite rhombs are present in recent marly deposits formed
under actual desert conditions.

Sand plays a part, apparently not hitherto observed, in the dis-
integration of rocks. It acts as innumerable wedges along joint-
planes and cracks.

Recent calcareous deposits are converted into gypsum, with
destruction of organic structures.

Sodium age sonnets and epsomite are common as encrustations
among the raised-beach and coral-reef deposits.

The age and distribution of the older salt and gypsum deposits
are considered. It is suggested that the beds are contemporaneous
with those of the Fayum, that is, are of Oligocene age. Close
comparisons are possible in certain cases between the formations
considered and those of the British Trias. he geology of the
islands at the mouth of the Gulf of Suez is shown by means of a
sketch-map (fig. 4, p. 205).

In conclusion, I have to acknowledge much valuable assistance
from Mr. 8. R. Illingworth in connexion with the chemical work
done in preparation of this paper. To him my best thanks are due,
as well as to my former pupil, Mr. Ewart Mather, who kindly
made a check-analysis of the saline sand. Lspecially do I owe
thanks to Prof. W. W. Watts, F.R.S., for much kindness both in
reading through the paper and in making suggestions with regard
to it.

EXPLANATION OF PLATES XIII-XVI.

Puate XIII.

Gully in the Um Esh range, showing the gap between the ‘gravel ’-terrace
and the main hills. The head cf the gully is filling with sand.

Prats XIV.

Fig. 1. View from the summit of a ‘ gravel ’-terrace: the plain is seamed with
radiating watercourses. In the distance are seen the salt-covered
sands and the Gulf of Jemsa.

2. Limestone almost entirely fretted away by wind-blown sand, north
of Jemsa.

Prats XV.

Fig. 1. Coarse sand with miniature dreikanter, from the plain between the
Um Esh and the Jebel Zeit ranges. Natural size.

2. White limestone-cliffs on Jubal Island, illustrating the effect of wind-
blown calcareous sand upon joint- planes. The projecting fossils show
the dip of the strata.

+

‘ATINS SHL SO GVSH AHL ONITIIS GNVS GNY STTIH NIVW SHL GNv
ONVY HSS WN AHL NI ATIND JO MGIA
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« < ‘Ageaq “07205 “py asoxmag

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HX Td LIAX'T “ICA ‘90S “1035 'nynop “LYUVNG®

<* = 7 + 3 :

sai a ‘ae is
ee a ee ee ee ee ee ee

Quart. JOURN. GEOL. Soc. VoL. LXVII, PL. XIV.

FIG. 1.—VIEW FROM THE SUMMIT OF A GRAVEL-TERRACE: THE GULF OF JEMSA
IS SEEN IN THE DISTANCE,

>

pn e>

A. W. Photo.

FIG. 2.—LIMESTONE ALMOST ENTIRELY FRETTED AWAY BY WIND-BLOWN SAND,
NORTH OF JEMSA.

-& nthe : kad

Si os ie ;

erg

A. W. Photo. Bemrose Ltd., Collo., Derby.

ne W3 ¥ = a - ; Sle We 4 F A ane Ge u Pe
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QuarT. JOURN. GEOL. Soc. VoL. LXVII, PL. XV.

FIG. 1.—COARSE SAND WITH MINIATURE ° DREIKANTER,’ FROM THE PLAIN BETWEEN
THE UM ESH AND THE JEBEL ZEIT RANGES: NATURAL SIZE.

FIG. 2.—WHITE LIMESTONE-CLIFFS, JUBAL ISLAND, SHOWING THE EFFECT OF
WIND-BLOWN CALCAREOUS SAND UPON JOINT-PLANES.

A, W. Photo. Bemrose Ltd., Collo., Derby.

ANE SA ET EET gO ITI

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QUART. JOURN. GEOL. Soc. VoL. LXVII, PL. XVI.

FIG. 1.—BLOCK OF GRANITE FROM THE UM ESH RANGE, SHOWING THE
FRETTING AWAY OF FELSPARS, THE OUTSTANDING QUARTZ, ETC.

—

A. W. Photo.

FIG. 2.—ARROWHEAD TWIN OF GYPSUM FROM JUBAL ISLAND, SHOWING
THE MECHANICALLY ETCHED FIGURES.

A. W. Photo. Bemrose Ltd,, Collo., Derby.

* be e

Vol. 67.] EASLERN DESERT OF EGYPT. 261

Pruate XVI.

Fig. 1. Block of granite from the Um Esh range, showing the fretting-away of
the felspar, the outstanding quartz, also the sand-grains driven into
the softer material and lodged between the quartz-grains. (T'wo-
thirds of the natural diameter.)

2. Arrowhead twin of gypsum from Jubal Isiand, showing the mechani-
cally etched figures. (Four-fifths of the natural diameter.)

Discussion.

Dr. C.G. Cuxnis suggested a special determination of the crystal-
rhombs described, in order to determine whether they were really
dolomite, and not calcite.

Sir Tuomas Hotianp supported the previous speaker’s suggestion
for a special check determination of the rhombohedral crystals of
supposed dolomite. Beautifully sharp rhombs are found in the
black mud of the Rajputana salt-lakes, but on chemical examination
they prove to be calcite, not dolomite. Recent work in the
Rajputaua Desert reveals many features described by the Author,
and long recognized as characteristic of the Triassic and other
salt-bearing formations : among these are the plano-convex shape of
the lenticular deposits; the contemporaneous formation of gypsum
and dolomite with the salt; and the distribution of pebbles in an
abundant sandy matrix, due to the action of sudden floods in desert
regions. The work done by the speaker in conjunction with
Dr. Christie (Rec. Geol. Surv. Ind. vol. xxxviii, 1909, p. 154)
showed that the salt, of which over 54 million tons exist in Sambhar
alone, is brought in in the form of fine dust from the coast of Cutch,
some 500 miles away to the south-south-west. With the fine
angular sand of the Bikaner Desert are found undamaged tests of
foraminifera, which must have been carried bodily by the wind
instead of being rolled with the heavier rounded sand-grains.

Dr. J. W. Evans was glad to find that the Author employed the
term dreikanter for the normal type of wind-worn stone with
three approximately parallel edges, and not for the more special
roughly tetrahedral form to which it was applied by some authors.
He was much impressed by the evidence brought forward of the
destruction of rocks by wind-action. He believed that many of
the so-called ‘ plains of marine denudation’ would prove to be the
resalt of wind-erosion, and instanced that on which the Cambrian
of the North-West of Scotland was deposited, as also the planed-
down surface of the Paleozoic strata in South Wales and elsewhere,
which was believed to date from the Triassic Period.

The Prestprnv (Prof. Warrs) regretted that time did not permit
of adequate discussion of the numerous and interesting points raised
in the paper. The Author had spent a very considerable time on
the ground and in working up his conclusions, and there could be
no doubt that the paper constituted an important addition to the
knowledge of desert conditions and deposits.

The AurHor thanked the President and the Fellows for the way

262 THE EASTERN DESERT OF EGYPT. [May rort,

in which the paper had been received. He said that the presence
of dolomite rhombs had first been suspected, as a result of analyses
made of that portion of the marly sediments which was soluble in
dilute acid. The rhombs were isolated by methods indicated by
Dr. Cullis, and compared with his specimens; but the method of
identification now described by him was not adopted. He was
glad to hear of the distances to which salt was carried by the
wind in Rajputana, since there was some indication of much the
same phenomenon in the part of Egypt now described. Foraminifera
were also carried to great distances, as in India; and the Author
was surprised to find unbroken foraminifera in sands filling the
gullies high up in the mountains. He agreed with Dr. Evans as
to the important part played by wind in erosion. The planing-down
effect. of the wind was especially well seen on the islands’ in the
Red Sea.

Vol. 67. THK TEETH OF PTYCHODUS. 263
7

8. On the Tunra of PrycHopus and their Distripuri0n in the
Enetish Cuark. By Grorek Kpwarp Distey, F.G.S. (Read
March 8th, 1911.)

[Pirates XVII-XXII. |

Introductory Remarks.

Amone the remains of fishes found in the Chalk, the teeth of
Ptychodus are so conspicuous and so easily recognized by the
quarrymen that they have long been collected in large numbers
and distributed to various museums. Most of these fossils, however,
bear no record of the exact lecality or zone from which they were
obtained, while groups of associated teeth have often been scattered
without any note of the circumstances of their discovery. I have,
therefore, devoted much attention during the past twenty years to
the careful collecting of teeth of Ptychodus from the chalk-pits of
the South-East of England, and I now propose to discuss their
classification and the zonal range of the various species.

I have collected especially in the Gravesend, Rochester, and
Medway-Valley area, where there are great excavations in a
continuous series of Chalk-deposits, from the base of the zone of
Ammoniies rhotomagensis to the top of that of dicraster cor-
angunum. I have also obtained specimens from the Caterham
Valley, Oxted, Merstham, and Betchworth; from Berkshire, Hamp-
shire, Bedfordshire, and Cambridgeshire ; and I have studied all
the material in the British Museum, the Museum of Practical
Geology (Jermyn Street), and the museums of Salisbury, Brighton,
and Rochester. I have been particularly fortunate in discovering
fitty sets of associated teeth, and have examined many more in
the museums just enumerated.

The arrangement of the teeth of Ptychodus in the mouth is
already known from specimens of Pt. decurrens found in the English
Chalk,’ and from others of Pt. mortoni found in the Chalk of Kansas
(U.S.A.).* Ihave obtained confirmatory evidence of it in a naturally
arranged group of teeth of Pt. decurrens, from the Lower Chalk of
Wouldham near Rochester; and in another group of the same
species given to me by Mr. G. Bishop, Manager of the Lime-Works
at Merstham (Surrey).

It appears that the teeth are arranged in antero-posteriorly
directed parailel rows, in symmetrical pairs on each side of a median
row, which contains the largest teeth in one jaw (presumably the
lower); while in the other (presumably the upper) the median row
consists of diminutive teeth somewhat long and narrow, with the
grooving of the enamel confined to the centre and across the width.

} A. Smith Woodward, Q.J.G. 8. vol. xliii (1887) pp. 121-80; and ibid.
vol. Ix (1904) pp. 133-35,

2S. W. Williston, Kansas Univ. Geol. Surv. yol. vi (Paleont.) pt. ii (1900)
pp: 234-40.

264 MR. G, E, DIBLEY ON THE TEETH OF PTYCHODUS {| May 1911,

The rows diminish in size from the inner pair outwards. In
Pt. decurrens there are not more than fifteen rows, while in Pt. mor-
ton there are seventeen rows of teeth. It is now, therefore, possible
to interpret the numerous sets of associated though scattered teeth
of other species, and to determine the variations which occur in
different parts of the jaw.

I shall treat the several species in the order of their appearance
in the English Chalk, and utilize the new material in defining them
more exaetly than earlier observers were able to do.

Description of the Fossil Teeth.

1. Prycuopus prcuRRENs Agassiz. (Pl. XVII, fig. 2; PL XT
figs. 20-24.)

1839. L. Agassiz, ‘ Poissons Fossiles,’ vol. iti; p. 154 & pl. xxv 4, figs. 1, 6, 7, 8, 21
(non tigs. 2-5).

Specific characters.—Central part of crown of tooth not
sharply raised, as a rule gently rounded or flattened. ‘Transverse
ridges small and numerous, extending to the lateral ridges and
leaving space for a minimum of granulation; these ridges are
sometimes bifurcating or intercalated, ending abruptly or curving
sharply on reaching the margin, seldom showing a concentric
arrangement ; also rarely subdivided into tubercles. Numerous
fine ridges extend at right angles to the transverse ridges, over
the anterior and posterior portions of the tooth ; this is a specially
distinctive feature. |

Variations.—The four naturally arranged sets of teeth already
described by Dr. A. Smith Woodward differ much from each other,
and illustrate well the difficulty of determining isolated teeth. In
the first specimen’ the fineness of the transverse ridges and grooves
is noteworthy, and the crown in the lower median teeth is only
slightly raised. In the second specimen (op. cit. fig. 2) the rela-
tively great extent of the granulated marginal area is unusual, and
the lateral teeth exhibit curious oblique distortion. In the third
specimen (fig. 3), which belongs to the upper jaw, the small median
teeth are peculiar in being nearly square, and the large teeth of the
inner paired series have a remarkably raised crown.

In my own collection I have an associated set of eighty-four teeth
from Wouldham which are identical with the foregoing, but the set
possesses an additional feature in that it contains, among others
of the lower jaw, one tooth of the median row which is charac-
terized by an unusually elevated crown. ‘This set contains seven
teeth of the upper median row. These small median teeth may
vary greatly, though similar in the individual, according to age.
In Pl. XIX, fig. 20 represents a median tooth in sitw belonging
to this set. The other six median teeth are identical in shape and
other features.

1 Q. J. GS, vol. xliii (1887) pl. x, fig. 1.

~~ — 4

ie

— =

. 7
.
-

Vol. 67.] AND THEIR DISTRIBULION IN THE ENGLISH CHALK. 265

The dimensions in millimetres of the principal teeth are as

follows :—
Length, Breadth.

Sninll median: bootie eee. raise see sew cee bck locales 8 6
Tooth from first inner paired row .............. baat 14 12
Tooth from central row opposite dentition ......... 14 Ai
Smallest: lateral Aematiee eg sors ecee ae ea ac sow ches. 8 4

These teeth evidently belong to a young Ptychodus.

Pl. XIX, fig. 21 represents a median tooth (the only one
preserved), belonging to an associated set of thirty-six teeth from
Bluebell Hill, Burham. It is evident that this tooth is more elon-
gated, though somewhat similar in shape; and, from comparison
with the other teeth in the set, the suggestion arises that age
accounts for the differences in shape, size, and development of the
grooving.

The dimensions in millimetres are as follows :—

Length. Breadth.

ll 5

Median tooth............. it ORE mee ee ee 5
Tooth of first inner paired row ...............0cceceeee 27 ae
Tooth of central row oppusite dentition ...... .... eee 23

Pl. XIX, fig. 23 represents the only preserved median tooth in
another associated set of twenty-three teeth, also from Bluebell
Hill.

The dimensions in millimetres are :—

Length. Breadth.

Wedltamn, fra pibig come ete: frei cick 2 eel3 passes cede 18 11
Tooth of first inner row, opposite dentition ......... 30 20
Tooth of central row, opposite dentition ............ 32 25

Pl. XIX, fig. 22 ineludes two median teeth united to inner
paired rows by iron pyrites, and they belong to the set figured in
Pl. XVII, fig. la. They are 14 mm. long and 9 mm. broad.

Pl. XIX, fig. 24 represents one of two isolated teeth from
Holborough, which evidently belonged to the largest form of Pt. (e-
currens ; 1t is 21 mm. long and 12 mm. broad.

The fine Brighton specimen described and figured by Dr. A. Smith
Woodward? may be regarded as a typical example of the species;
and I have discovered a few median teeth of the upper jaw of
the same form in the zone of Holuster subglobosus (Pl. XIX,
fig. 22).

The foregoing sets belonged to individuals which possessed small
teeth, the largest being only 14 mm. in length and 10 mm. in
breadth, compared with others whose corresponding teeth are
ol mm. long and 36 mm. broad.

Besides these, there are still more marked varieties which have
already received specific names, and I now proceed to describe
them.

' Where measurements are given, the length is reckoned parallel to the
grooving, and the width from the anterior to the posterior portion of the
tooth, except in the case of the small median teeth, in which case they are
reversed.

4 Q. J.G.S. vol. xiiii (1887) pl. x, fig. 2.

266 MR. G.E. DIBLEY ON THE TEETH OF PTYCHODUS [May 1911,

PrycHoDUS DECURRENS, Var. DEPREssUS (Dixon). (Pl. XVII, figs. la
& 1 b.)

Though described as belonging tv a distinct species, Pt. depressus,
by Dixon,’ the teeth of this form only differ from those typical of
Pt. decurrens in being somewhat more flattened and depressed. They
are common in the zone of Holaster subglobosus, and I have found
interesting associated sets in the pit at Bluebell Hill, Burham
(B.M. P 10255), and in Peter’s Pit, Wouldham (B.M. P 10336).
The latter specimen comprises fifty teeth, of which thirty-two
occur still in their natural arrangement, showing a small portion
of the dentition of the upper jaw (PI. XVII, fig. 1a). From front
to back this dentition is very convex, and the teeth do not appre-
ciably increase in size backwards. The usual median row of small
teeth is partly obscured by the crushing together of the large teeth
of the inner paired series.

PrycHoDUs DECURRENS, var. OWENI (Dixon). (Pl. XVIII, figs. 1-11
Scale) RX ig. 8.) |

The teeth described as Pt. owent by Dixon” have not hitherto
been found in their natural arrangement; but I have selected the
isolated specimens shown in Pl. XVIII, figs. 1-11, to prove that
there is every gradation between them and the normal teeth of
Pt. decurrens. Indeed, it seems probable that the peculiarly
irregular and broken ridges that characterize Pt. oweni occur chiefly
on the principal median teeth; for in one set, which evidently
belongs to a single individual (B.M. 39187-88), many of the
larger teeth correspond exactly with those described as Pt. owen,
while several of the smaller lateral teeth are typically those of
Pt. decurrens. I have also observed the same variability of the
ridging on the teeth in other associated sets.

The type tooth and three other specimens in the Bowerbank
Collection are labelled as having been obtained from Snodland,*
Rochester. I have found two similar teeth from this locality, where
only the Lower Chalk was worked at the time.

From Oxted I obtained, quite recently, an associated set of
fourteen teeth of Pt. decurrens which proved to be worthy of note.
Three of the central teeth of the lower dentition are of an extra-
ordinary size, the largest being 51 mm. in length and 42 mm. in
breadth (Pl. XIX, figs. 1-3). The grooving on the posterior half
is of the typical form, while the next four or five adjoining rows are
sharply curved towards the anterior portion, their ends being sharply
recurved and extending to the front edge of the tooth. Nearly
the whole of the anterior half is occupied by numerous secondary
grooves radiating from the centre, and thus partakes of the features
belonging to the variety owen. Of the remaining teeth, there are

1 «Geology of Sussex’ 1850, p. 863 & pl. xxxi, fig. 9.
2 Ibid. p. 364 & pl. xxxi, fig. 2.
S$ Halling is the proper locality, Snodland being situated on the Gault. ©

Vol. 67.] AND THELR DISTRIBUTION IN THE ENGLISH CHALK, 267

seven large teeth belonging to the lateral rows, of which six are
much deformed as regards shape; two are shown in Pl. XIX,
figs. 4 & 5, The grooving also is very abnormal in many of the
teeth.

There is a set in the British Museum (Bowerbank Collection,
39138) from Wouldham, and another which is labelled as coming
from Halling, though it evidently belongs to the previous set: as can
be seen from the matrix, the peculiar staining, and the abnormality
in shape and grooving resembling the Oxted set, but with an addi-
tional feature in the form of small papille developed in the grooves
(BE XVILL, fie 4G BIOXEX, fie. 15),

PrycHoDUS DECURRENS, var, MULTIstRIaATUS (A. 8S. Woodward).
(Pl XVILE fies. 12% 13; Pl. XIX, figs, 6, 10, 12,'&'14.)

The so-called Pt. multistriatus (A. 8. W.)* from the zone of
Holaster subglobosus comprises large teeth marked with numerous
fine ridges, which are sharply recurved into a concentric arrange-
ment. I am now able to prove, however, that these are merely
from the inner rows of a dentition in which the outer teeth conform
to the typical Pt. decurrens plan: for, in 1905, I obtained from the
same zone at Holborough, near Rochester, an associated set of
seventeen teeth, of which only those of the large median lower row
are typical examples of the so-called Pt. multisirvatus ; while those
of at least six paired rows exhibit every gradation between this
condition and that of the true decurrens-ridging, which characterizes
the outermost rows. Some of these gradations may even be seen
in the type-specimen in the British Museum (P 2681).

PrycHODUS DECURRENS, var. La=vis (A. 8. Woodward).

The very small and remarkably smooth teeth from the Lower
Chalk, described as Pt. levis (A. 8. Woodward)’, exhibit the
characteristic grooving of Pt. decurrens, and can only be regarded as
a dwarfish variety. 1 have observed a similar abnormal smoothness
in a tooth of Pt. mammillaris in my own collection. Several
examples are now known; and I have obtained them from the
zone of Holaster subglobosus, both at Betchworth and at Burham.

Geological Range,

Ptychodus decurrens occurs chiefly in the zone of Holaster sub-
globosus. It is also found, but rarely, in the Actinocamaa-plenus
Marls, and still more rarely in the base of the zone of hynchonella
cuviert. Ithas not hitherto been discovered at any higher horizon.
Two teeth of this species are in the Museum of Practical Geology
(Jermyn Street), and are said to have been obtained from the

* Catal. Fossil Fishes Brit. Mus. pt. i (1889) p. 146 & pl. v, figs. 4-6.
? Proc. Geol. Assoc. vol. xiii (1893-95) p. 192 & pl. v, figs, 5-6.

%

268 MR. G, E, DIBLEY ON THE TEETH OF PTYCHODUS [May r911,

Upper Greensand. I have not yet obtained a specimen from the
zone of Ammonites rhotomagensis.'

It is interesting to note that Pt. decurrens is the only species from
the English Chalk of which the teeth have been found in their

natural arrangement.

2. Prycnopus potyerrus Agassiz. (Pl. XX, figs. 1&2; Pl. XXI,
figs. 1 & 2.)
1839. L. Agassiz, ‘ Poissons Fossiles’ vol. 1, p. 156, pl. xxv, figs. 10-11 &
pl. xxv 8, fig. 23.

Specifie characters.—Central part of crown of tooth flattened.
‘Transverse ridges relatively large, curving round more or less at the
lateral ends, sometimes forming gyrations; marginal granulated
area usually of considerable extent, coarsely marked, never impressed
with radiating grooves.

Variations.—tThe teeth referred to this species are remarkably
varied, and Agassiz divided them into four groups to which he gave
provisional names. My studies of numerous associated sets of
teeth prove that there are gradations between the extreme types,
and I therefore continue to regard the different forms merely as
varieties.

In the typical Pt. polygyrus, as defined by Agassiz, the principal
teeth are much flattened, the grooving is very coarse, with frequent
eyrations, and the marginal granulation is only wide in some of the
large teeth of the lower median row. One of these lower median
teeth is figured by Agassiz” under the name of Pt. latissemus. The
finest known specimen, showing the greater part of the dentition
of both jaws, was obtained by Mr. W. Murton Holmes from the
zone of Wicraster cor-anguinwm at Banstead (Surrey), and is now
in the British Museum (P 10771). It comprises about 150 scattered
teeth, which I have been able to arrange approximately in their
natural order. Besides those of the median series, there are also
teeth of five or six paired rows in each jaw, and a selection is
shown in Pl. XXI, figs. 1 & 2.

An associated set of about twenty similar teeth has been discovered
by Mr. C. Gosling, in the same zone of the Chalk, at Croydon; and
it may be added that there is another set in the British Museum
(P 4551) from the Chalk of Normandy.

The form just described appears to be characteristic of the
Micraster cor-anguinum Zone.

1 [After this paper had been read, Mr. E. 'T. Newton kindly told me that there
was a tooth of Ptychodus among a collection of fossils from the Potton Beds of
the Lower Greensand, at the Museum of Practical Geology, Jermyn Street. I
have now seen this specimen, which is iron-stained just as are the other
fossils from this horizon: it is undoubtedly a tooth of Pt. decurrens var. de-
pressus. It was unrecorded by Mr. Keeping in ‘ The Fossils & Palzontological
Affinities of the Neocomian Deposits of Upware & Brickhill’ Cambridge, 1883.
T consider it to be a derived fossil— G. L. D., March 22nd, 1911, |

2 Op. cit. pl. xxv a, fig. 8.

Vol. 67.| AND THEIR DISTRIBUTION IN THE ENGLISH CHALK. 269

PrycHoDUS POLYGYRUS, Var. CONCENTRICUS (Agassiz).

This name was given by Agassiz‘ to an imperfect tooth from the
Upper Cretaceous of Quedlinburg, characterized by a rather high
crown, well-marked concentric ridges in the inedian part, and a
wide margin of fine granulation. I have not found any exactly
similar teeth in the English Chalk; but one which very nearly
approaches it, from the Holaster-subglobosus Zone at Bluebell Hill,
1 consider to be one of the abnormal forms of Pt. decurrens
(Pl. XIX, fig. 18).

PrycHopUS POLYGYRUS, Var. MARGINALIS (Agassiz). (Pl. XXI,
tigs. 4a—4+¢.)

As defined by Agassiz,° the teeth of this form have a flattened
raised median part, crossed by numerous ridges, which are only
sometimes concentric, and bounded by a wide coarsely granulated
area. I have only met with one tooth (Pl. XXI, fig. 4a) from
Halling and an associated set of fifteen teeth from Bluebell Hill
(zone of Terebratulina gracilis) which well illustrate the foregoing
features ; two teeth belonging to this set are figured with the
previous example (figs. 4 6 & 4c). They tend to connect Pt. poly-
gyrus with Pt. mammillaris.

Teeth of Ptychodus polyyyrus are commonest in the zones of Rhyu-
chonella cuviert and Terebratulina gracilis. ?

An associated set of about fifty teeth of this variety from Beachy
Head (B.M. P 6141) is marked by parallel grooves with
only slightly curved ends; and there are also similar sets
in the British Museum from Halling and Bluebell Hill (36747,
47907). IL have also sets from Burham and Wouldham which agree
with those just mentioned (Pl. XXII, fig. 2). In some cases,
however, the teeth are fairly flat and the grooves onthe
teeth are finer, more numerous, and often concentric,
at least in the principal rows; and I have obtained in-
structive examples from Tingey’s Pit, Wouldham. In one
associated series of a hundred and thirty teeth (B.M. P 10464),
which contains six of the small median teeth, I have been able to
arrange and identify most of the rows of both jaws. Three teeth
from the (hypothetical) upper set are shown (PI. XXII, fig. 1).

An associated set of seventeen teeth from the zone of Actinocamaa:
quadratus of Northern France described by M. Leriche ’ is of much
interest, as showing a gradation between Pt. polygyrus and
Pt, latissimus. Nearly similar are some teeth from Wantage, pre-
served in the Museum of Practical Geology.

An interesting variety is shown in Pl. XXJ, fig. 3, which consists
of five teeth selected from an associated set containing twenty-two

1 * Poissons Fossiles’ vol. ii (1835-45) p. 156 & pl. xxv 4, fig. 22.

2 Ibid. p. 157 & pl. xxv, figs. 4-8.

3 * Réyvision de la Faune ichthyologique des Terrains crétacés du Nord de la
France’ Ann. Soe. Géol. Nord, vol. xxxi (1902) p. 99 & pl. ii, fig. 23.

270 MR. G. E. DIBLEY ON THE TEETH OF PTYCHODUS | May 1911,

teeth from Dunton Green (probably the top of the Rhynchonella-
cuviert Zone). These teeth are very tlat, and possess a finely
granulated margin, which is very broad on the small
lateral teeth.

PrycHODUS POLYGYRUS, Var. SULCATUS (Agassiz).

The teeth thus named’ are essentially intermediate between
Pt. polygyrus and Pt. decurrens. Until similar specimens are
discovered in an associated set, it is impossible to decide which
species they represent.

Geological Range.

The typical teeth of Pt. polygqyrus are found exclusively in the
zone of Micraster cor-anguinum. ‘The species ranges from the zone
of Rhynchonella cuviert upwards to that of I. cor-anguinum, where
it is rare, and afterwards disappears.

Teeth of the typical form, from the Niobrara Chalk of Kansas
(U.S.A.), have also been described under the name of Pt. martini by
Prof. Williston2

3. PrycHopus Latissimus Agassiz. (PI. XX, figs. 3-5.)
1839. L. Agassiz, ‘ Poissons Fossiles’ vol. iii, p. 157, pl. xxv@ & pl. xxv,
figs. 24-26.

Specific characters.
Transverse ridges very large and few, four or five in the big
median teeth, two or three in the small lateral teeth; slightly
curved at the ends. The coarse marginal granulation laterally
tends to continue the transverse ridges, and is anteriorly arranged
in more or less distinct radiating lines.

Observations.—This species is well marked, and the teeth
referred to it are less variable than those of other species. I have
obtained an associated series of thirty-six teeth from the zone of
Holaster planus at Bluebell Hill, Burham (Pl. XX, fig. 3), and
there 1s another series (artificially arranged on a block of chalk) in
the Willett Collection, Brighton Museum.

Geological range.—Most of the teeth of this species have
hitherto been found isolated, and I have only met with them in
the zones of Terebratulina gracilis and Holaster planus in Kent
and Surrey.

4, PrycHopvs DIxonI, sp. nov. (Pl. XX, figs. 1 & 2.)
1850. Pé. latissimus, Dixon (non Agassiz), ‘ Geology of Sussex ’ p. 362 & pl. xxx,
figs. 1&2. [Fig.2is Pt. polygyrus (Ag.), high zonal form. |
“~The tooth figured by Dixon as Pt. latissumus differs from other
known species; it does not agree with Agassiz’s type, which is
shown in fig. 3, and to which Dixon gave the name of Pt. pauci-
sulcatus, evidently in error.

’ Op. cit. p. 156, pl. xxv, fig. 9 & pl. xxv J, fig.
2 Univ. Geol. Surv. Kansas, vol. vi neon pt. ii (1900) p. 240.

Vol. 67.] AND THEIR DISTRIBUTION IN THE ENGLISH CHALK. 271

In 1898 I discovered in the Yerebratulina-gracilis Chalk at
Whyteleafe a tooth which I failed to recognize; subsequent dis-
coveries of an associated set of thirty-six teeth in the same zone at
Cuxton, in which the features exhibited by the Whyteleafe tooth
were persistent throughout the set (Pl. XX, fig. 1), and of another
associated set of fourteen teeth from the same locality, have con-
firmed my reasons, with which Dr. A. S. Woodward agrees, for
treating this as a new species.

Specific characters.—Shape: lateral teeth more oblong than
in the previously described species; central teeth of large inner
paired row of (presumably) upper dentition nearly square. Grooving
not nearly so coarse as in Pt. latissimus, but more so than in Pt.
polygyrus, with a tendency to occupy the whole surface of the
lateral teeth and a curving of the ends towards the anterior portion
of the tooth, as in Pt. latissimus. The granulated area is less than
in Pt. latissimus and Pt. polygyrus var. marginalis, notably in the
anterior portion of the lateral teeth, while in the big central teeth
the granules are very coarse where they adjoin the last groove;
this area is somewhat increased in these large teeth.

The evidence from which these features were obtained is (1) the
tooth already mentioned; (2) the associated set (B.M. P 10260);
(3) an associated set of eleven large teeth—in all probability from
the first inner paired rows of the upper dentition,—and three
smaller teeth belonging to the same set from the Z’erebratulina-
gracilis Zone at Cuxton and kindly lent by Mr. J. G. Wilson for
comparison with the other examples: one of these large teeth is
shown of the natural size in Pl. XX, fig. 2; (4) a tooth recently
obtained from the same locality ; (5) an associated set from Lewes
(B.M. 4355); and (6) an associated set, Dixon Collection (B.M.
28339).

Geological range.—This species has been so far recorded
only from the zone of Zerebratulina gracilis, and probably from
that of Holaster planus.

5. Prycuopus MAMMILLARIS Agassiz. (Pl. XXII, figs. 3-5.)

1839. L. Agassiz, ‘Poissons Fossiles’ vol. iii, p. 151 & pl. xxv 8, figs. 12-20
(non 11).

1850. Ptychodus latissimus F. Dixon, ‘Geology of Sussex’ pl. xxxi, fig. 3
(errore).

Specific characters.—Central part of crown of tooth sharply
raised. ‘Transverse ridges numerous, extending directly across the
raised part and continued down its sides, sometimes tending to be-
come gyrate at the ends. Granulated marginal part of the tooth
very wide, fine, usually crossed by a few shallow radiating
channels; granules tending towards a concentric arrangement.
Lateral teeth very unsymmetrical (Pl. XXII, fig. 4).

Remarks.—The four type-specimens in the Mantell Collec-
tion are isolated teeth with remarkably flattened crowns. Others
are more rounded at the summit of the raised portion. Many
specimens exhibit some approach to the teeth of Pt. polygyrus, but
they can always be distinguished by the character of the marginal

@. J. GS Noe S66: T

272 MR.G.E,DIBLEY ON THE TEETH oF PTYCHODUS [May 1911,

granulated area. In one associated set of six teeth (B.M. 4362)
some of the transverse ridges are irregularly subdivided, as in
Pt. decurrens var. owent (Pl. XVIII, fig. 3).

Geological range.—This species ranges through the zones of
Rhyuchonella cuviert, Terebratulina gracilis, and Holuster planus,
and may also occur in that of Mvcraster cor-testitudinarium. A
variety from the base of the Rhynchonella-cuviert Zone at Burham-
and Betchworth is characterized by an unusually fine marginal
granulation, in which the radiating grooves are scarcely noticeable
or are entirely absent (Pl. XXII, fig. 5).

6. Prycnopus rugosus Dixon. (Pl. XXII, figs. 6a & 6 6.)
1850. F. Dixon, ‘ Geology of Sussex’ p. 362 & pl. xxxi, fig. 5.

Specific characters.—Teeth resembling those of Pt. mammil-
laris, but remarkably smooth; both the transverse grooving and
the marginal granulation are feebly marked; the grooves are fewer
than in Pt. mammillaris.

Remarks.—The crowns of the typical teeth are rounded, and
there is often a characteristic puckering. When they are more
flattened and begin to show some distinct surface-markings, they
approach the teeth of Pt, mammillaris. In an associated set in the
British Museum (P 5335), and in another set in my own collection,
the typical teeth occur together with smaller teeth which have an
excessively elevated crown and smooth sides. These smaller teeth
were erroneously named P¢. ultior by Dixon.’

Geological range.—/t. rugosus seems to appear first, in the
zone of Micraster cor-testitudinarium, and has not been found
above that of J. cor-anguinwm. I have obtained teeth from the
Haling Pit (Purley), Strood, and Gillingham. In the British Museum
(Natural History) there are also specimens from Purley Junction
Pit (now disused) and Northfleet. Teeth of the same form, from
the Niobrara Chalk of the Western States of North America, were
named Pt. whipplec by J. Marcou.?

7. PrycHopus mortont Agassiz. (Pl. XXII, figs. 7 & 8.)
1839. L. Agassiz, ‘ Poissons Fossiles’ vol. 1ii, p. 158 & pl. xxv, figs. 1-3.

Specific characters.—Central part of crown of tceth raised
to a point, from which grooves and ridges radiate irregularly ;
marginal area wide, and finely granulated.

Remarks.—Although common in the Cretaceous of North
America,’ whence the type-specimen was obtained, this form of
tooth is extremely rare in the English Chalk.

Dixon * figures a specimen from Shoreham, and Dr, A. 8. Wood-
ward’ another from Winchester; apparently the crown alone of

1 ‘Geology of Sussex’ 1850, p. 362 & pl. xxx, fig. 10.

2 «Geology of North America’ Ziirich 1858, p. 33.

BW Williston, Kansas Univ. Geol. Surv. vol. vi (Ealnone pt. i (1900)
pp. 234-40.

4 «Geology of Sussex’ 1850, p. 364 & pl. xxxi, figs. 6-7.

5 Proc. Geol. Assoc. vol. xiii (1893-95) p. 191 & pl. v, fig. 4.

Vol. 67.] AND THEIR DISTRIBUTION IN THE ENGLISH CHALK, 273

this tooth has been preserved (Pl. XXII, fig. 8). I have not been
fortunate enough to discover any examples.

The range of the English species of Ptychodus is summarized in
the following synopsis :—

'
~” . ~
Sat Sf se - |2 S
aan oth ee lesaie: L/S
= Sc les | Sos =
N S F ‘ = S|, aS Ql. =| d
NAMES OF SPECIES ze Ses ee ies) =
AND a elels |S) S [esi ¢
a 2 S S Sy liens S| Ss
‘VARIETIES. Bee se Sle [es tee S
2 a ea o — S Ss iS = Ke
é\s 4/eiaiH iS /s
qi 3 ml SH = aH GH 4 Sey
AO ow S| St Sy re iS)
Bie See Bal -O. eG = S
een oneal eo So }
POS isa Suis ;|N IN | SN
Ptychodus decurrens..... OP
|
a var. multistriatus... —
Pi WAT) OWDENI en cep anes: ==
35 var. depressus .....
Pt. POY GUTNG SS ae, Pees
PE. labissemnas hs | |
Pt. dixont ... | |
(Se
Pt. mammillaris | |
Pt. PUGSSUS: (Bree ME rea omens
PE WORGONB eg oes | j

Concluding Remarks.

In concluding these observations on the genus Ptychodus, it is my
pleasant duty to offer my sincere thanks to many friends for their
assistance during the compilation of the foregoing facts. Among
these I may mention Mr. H. A. Allen, Dr. H. P. Blackmore,
Mr. C. Gosling, Mr. W. Murton Holmes, Dr. F. J. Kitchin,
Mr. E. T. Newton, Mr. R. B. Newton, Dr. A. W. Rowe, Mr. C.
Davies Sherborn, Dr. Ivor Thomas, Mr. Toms (of Brighton),
Mr. Henry Woods, Mr. George Payne (of Rochester), and Mr. R. M.
Brydone. I am also greatly indebted to Mr. Eustace Large for
many photographs and lantern-slides during the earlier period of
the preparation of this paper, and recently to Mr. Philip Dollman,
to whom I am especially indebted for his unceasing interest in
connexion with the majority of the lantern-slides, photographs,

274 MR. G. E, DIBLEY ON THE TEETH OF PTYCHODUS [May 1911,

and enlargements necessary for the elucidation of the subject.
Finally, I wish especially to offer my warmest. thanks to Dr. A.
Smith Woodward, who has not only been my constant friend and
adviser throughout the preparation of this paper, but has always
inspired and fostered my energies towards unravelling the zonal
history of the Fishes of the English Chalk.

EXPLANATION OF PLATES XVII-XXII.

Puatse XVII.

Fig. 1a. An associated set of teeth of Ptychodus decurrens (Ag.) var. depressus
of Dixon; from the zone of Holaster subglobosus, Burham, near
Buchesten found im situ. The lower portion illustrates the curva-
ture of the palate, the whole series belonging to the upper dentition.

Fig. 16. A detached portion of the above set containing three small median
teeth ; this group is cemented by pyrite, and is of the natural size.
(B.M. P 10336, G. E. Dibley Coll.)

Fig. 2. An associated set of Ptychodus decurrens (Ag.), found im sttw and re-
presenting part of the lower dentition; from the zone of Holaster
subglobosus, Merstham (Surrey). Slightly less than natural size.
(G. E. Dibley Coll.)

Puate XVIII.

Figs. 1-11. A series of teeth preserved in the British Museum (Natural History),
hitherto named Ptychodus oweni (Dixon): to show that they
merely represent a phase of SxeGme variation of Pt. decurrens.
(Compare figs. 3, 5, & 8 with figs. 1, 2, 3, & 17 of Pl. XIX.) Three-
eighths of the natural size.

Figs. 12 & 13. Part of an associated set of teeth of Ptychodus decurrens,
arranged hypothetically to represent (12) part of the upper den-
tition and (13) part of the lower dentition. This set.also illustrates
extreme variation; the big central teeth were known formerly as
Pt. multistriatus (A. 8S. Woodward). Half of the natural size.

Puate XIX.

Figs. 1-3. Three teeth of Ptychodus decurrens (part of an associated set)
belonging to the central row of the lower dentition, and illustrating
abnormal development of the enamel (figs. 4 & 5 also belong to
the same individual, and illustrate malformation). Half of the
natural size. From the zone of Holaster subglobosus, Oxted (Sur oy
The largest tooth is 5°7 centimetres long and 5 cms. broad. (G. EH
Dibley Coll.)

Figs. 4-19. A series of teeth of Ptychodus decurrens, arranged to show marked

~ variation of the species. From the zone of Holaster subglobosus of
various localities. Half of the natural size. (G. EH. Dibley Coll.)

Figs. 20-24. Median teeth of the upper dentition of Ptychodus decurrens
belonging to five individuals, and arranged according to age (see
p- 265 in regard to dimensions). No. 22 belongs to the set shown
in Pl. XVII (B.M. P 10336, G. E. Dibley Coll.).

Fig. 25. Posterior aspect of a tooth of Ptychodus decurrens, showing the fine
grooves developed at right angles to the crown and continuous to the
root, a great characteristic of this species; from the
zone of Rhynchonella cuviert, Betchwor th (Surrey). (G. E. Dibley
Coll.)

Fig. 26. Terminal tooth of one of the lateral rows of a small Ptychodus
decurrens bordering the anterior portion of the palate, belonging to
an associated set from the zone of Holaster subglobosus, Wouldham,
near Rochester, Very slightly enlarged. (G. EH. Dibley Coll.)

——— —

»)

QuaRT. JourN. GEOL. Soc. VoL. LXVII, PL. XVII.

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TEETH OF PTYCHODUS DECURRENS.

Philip Doliman, Photo.

QuarRT. JOURN. GEOL. Soc. VoL. LXVII, PL. XVIII.

Philip Doliman, Photo, Bemrose Lid., Collo., Derby.
TEETH OF PTYCHODUS DECURRENS.

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TEETH OF PTYCHODUS DECURRENS.

Philid Doliman, Photo.

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QuaRT. JourRN. GEOL. Soc. Vou. LAVH, Pi: OX:

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Bemrose Ltd., Collo., Derby.
TEETH OF PTYCHODUS DIXON! & PT. LATISSIMUS.

Philip Doliman, Photo.

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Philip Doliman, Photo,

QuART. JOURN. GEOL. Soc. VoL. LXVII, PL. XXI.

Bemrose Lid., Collo., Derby.
TEETH OF PTYCHODUS POLYGYRUS.

QuarT. JOURN. GEOL. Soc. VoL. LXVII, PL. XXII.

9.
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Philip Doliman, Photo. Bemrose Ltd., Collo., Derby.

TEETH OF PTYCHODUS POLYGYRUS, PT. MAMMILLARIS,
PT. RUGOSUS, & PT, MORTONI.

Vol.67.] AND THEIR DISTRIBUTION IN THE ENGLISH CHALK. 275

Puatse XX.

Fig. 1. Part of an associated set of teeth, arranged to show a portion of the
upper dentition of Ptychodus dixoni, sp. nov.; from the zone of
Terebratulina gracilis, Cuxton, near Rochester. Slightly more than
two-thirds of the natural size. (B.M. P 10260, G. H. Dibley Coll.)

. Large tooth of Ptychodus dixoni belonging to the lower dentition. (This
tooth forms part of an associated set of fourteen teeth, the majority
comprising the large*teeth of this dentition.) Natural size. In the
possession of Mr. J. G. Wilson, Cuxton.

Fig. 3. Part of an associated set of teeth of Ptychodus latissimus Ag., ar-

ranged to illustrate part of the lower dentition. From the zone of

Holaster planus, Bluebell Hill, Burham, near Rochester. (G. E.

Dibley Coll.)

Fig. 4. A tooth from the central row of the above. Natural size.

Fig. 5. A tooth from the central paired row of opposite dentition, and belonging

to the same set. Natural size.

bo

Fig.

PuatTe XXI,

Fig. 1. Part of an associated set of teeth of Ptychodus polygyrus Ag., high
zonal form, arranged to illustrate part of the upper dentition.

Fig. 2. Part of the same set, to illustrate the lower dentition. Note the varia-
tion in development of the grooving of the enamel. The biggest
tooth of the central row shown in this figure measures 7 centi-
metres in length and 6°5 cms. from back to front. From the zone
of Micraster cor-anguinum, Banstead (Surrey). (B.M. P 10771.)

Fig. 3. Part of an associated set of teeth of Ptychodus polygyrus Ag., low

zonal form, nearly flat and showing broad marginal granulation.

Zone of Rhynchonella cuviert (upper portion), Dunton Green. The

largest tooth is 5°5 centimetres long and 4 cms. broad. (G. E.

Dibley Coll.) Half of the natural size.

Fig. 4. Three teeth of Ptychodus polygyrus var. marginalis (Ag.). The biggest
tooth is slightly less than natural size. and is from the zone of
Terebratulina gracilis, Halling, near Rochester. The two smaller
belong to an associated set of teeth from the same zone, Bluebell
Hill, near Rochester. (G. E. Dibley Coll.)

Puate XXII,

Fig. 1. Three teeth belonging to an associated set of 129 of Ptychodus poly-
gyrus Ag., having a flat surface and the grooving gyrate. From
the zone of Terebratulina gracilis, Wouldham, near Rochester.
Slightly less than natural size. (B.M. P 10464, G. E. Dibley Coll.)

Fig. 2. Part of an associated set of teeth of Ptychodus polygyrus, Ag., with the
grooving nearly parallel. From the zone of Terebratulina gracilis,
Bluebell Hill, Burham. (G. E. Dibley Coll.) Five-eighths of the
natural size.

Fig. 3. Part of an associated set of teeth of Ptychodus mammillaris Ag., from
the zone of Terebratulina gracilis, Cuxton, near Rochester. Half of
the natural size. (G. E. Dibley Coll.)

Fig. 4. Part of an associated set of teeth of Ptychodus mammillaris belonging
to the edge of the palate. Zone of Holaster planus, Cuxton.
Slightly more than half of the natural size.

. Tooth of Ptychodus mammillaris Ag., low zonal form. Zone of
Rhynchonella cuviert, Betchworth (Surrey). ‘J'wo-thirds of the
natural size.

Figs. 6a &6 6. Part of an associated set of teeth of Ptychodus rugosus Dixon.
Zone of Micraster cor-testitudinarium, Purley. The terminal tooth
of the above set is enlarged to nearly three-quarters of the natural
size (fig.60), and is from the base of the Micraster cor-anguinum
Zone, Chatham, (G. EH. Dibley Coll.)

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276 THE TEETH OF PTYCHODUS AND THEIR [May 1g1t,

Fig. 7. Lateral end tooth of Ptychodus mortoni Ag., from Kansas (U.S.A.).
Slightly less than the natural size.

Fig. 8. Tooth of Ptychodus mortoni Ag., in the Oxford University Museum,
from the Chalk near Winchester. (Photograph from drawing in
Proc. Geol. Assoc. vol. xiii, 1893-95, pl. v, fig. 4.)

Fig. 9. Terminal tooth of Ptychodus polygyrus Ag., belonging to the set shown
in fig. 3 of Pl. XXI. Natural size.

Discussion.

Mr. E. T. Newton said that he was glad of the opportunity of
testifying to the great value of the paleontological work which the
Author had been carrying on for a number of years, and was gratified
to think that at length an important piece of it was likely to be
published. Although Ptychodus teeth from the Chalk were so
commonly to be seen in collections of fossils, hitherto little had
been known as to the horizons from which they came ; but now the
Author, by careful collecting, had ascertained both the horizons and
the localities from which each species was obtained. Then again,
as regarded the arrangement of these teeth in the fish’s jaws, very
little was known—although Dr. Smith Woodward published some
valuable information about this some years ago. The present
Author, however, had obtained several examples with a number of
teeth in their natural relations; and his study of these had largely
extended the bounds of knowledge, and enabled him to show the
wide variation in the form and pattern of the teeth contained in the
mouth of one individual fish. Thespeaker congratulated the Author
on the accomplishment of an extremely valuable and interesting
piece of work.

Mr. W. Morton Hotmes said that the group of teeth of Ptychodus
polygyrus found by him was obtained from the upper part of the
Micraster cor-anguinum Zone in the railway-cutting close to
Banstead Station, about 24 feet below the surface.

Dr. A. Surra Woopwarp remarked on the exhaustive character of
the Author’s researches, and considered that he had now placed
the naming of the teeth of Ptychodus on a satisfactory basis. The
speaker regretted that there was still no clue to the predecessors of
the genus, but was much interested in the Author’s observation that
the feebly-ridged teeth of Pt. rugosus occurred only in the Upper
Chalk. He thought that recent discoveries still favoured the idea
that Péychodus was a forerunner of the Myliobatide and Trygonide,
and alluded to the grooves just becoming evident in the roots of the
teeth of Apocopodon, found in the uppermost Cretaceous rocks of
Brazil and Africa.

Mr. G. W. Youne confirmed the Author’s statement as to the
infrequency of the finding of Ptychodus teeth by the collector him-
self, compared with their abundance in museums. Ptychodus was
not really a common fossil, but its teeth having a conspicuous
colour, definite shape, and high lustre, readily caught the eye of the
quarryman, who preserved every specimen that he saw. When
purchasing specimens it was necessary to enquire carefully whether

Vol. 67.] DISTRIBUTION IN THE ENGLISH CHALK. 277

they were found in the quarry in which they were offered for sale,
for otherwise their value as evidence of zonal distribution might be
lessened.

The Auenor thanked the Fellows present for their appreciative
reception of his paper. He felt that the group of teeth discovered
by Mr. Murton Holmes was one.of the most important specimens
that he had to bring before the meeting. In buying fossils from
quarrymen he always exercised due caution, and was convinced that
there was no doubt about any of the records that he had included
in his paper.

278 DR, A. S. WOODWARD ON SOME MAMMALIAN [May 1911,

9. On some Mammattan TEETH from the WEALDEN of Hastines. By
Artur Smita Woopwarp, LL.D.,.F.R.S., F.LS., Sec.G.8.
(Read March 22nd, 1911.) }

Styce the late Prof. Marsh’s discovery of mammalian teeth and
bones in the coarse grits of the Laramie Formation in Wyoming
(U.8.A.), Mr. Charles Dawson, F.G.S., has persistently searched for
similar fossils in deposits of the same nature in the Wealden
formation of Sussex. These beds consist chiefly of coarse quartz-
grains mingled with teeth of fishes and fragments of bones, and
were originally noticed by Mantell under the name of ‘Tilgate
Grit.’ According to Mr. Dawson’s observations, however, they
form only small lenticular deposits, and occur at several horizons
in the Wealden Series.

The first result of this search was the discovery of a molar of
Plagiaulax, which I described and named Pl. dawsoni in 1891.)
More recent work, in which Mr. Dawson has been helped by Messrs.
P. Teilhard de Chardin and Félix Pelletier, has led to the finding of
three additional specimens—two probably belonging to Plagiaulax
itself, the third to a distinct though related genus. The first-
described tooth was met with in the Wadhurst Clay behind
St. Leonards, while the three new teeth were obtained from the
Ashdown Sands of the Fairlight Cliffs near Hastings.

The two new molars which seem to belong to Plagiaulax are
unfortunately very imperfect. In one the crown is seen to-be
closely similar to that of the original tooth of Pl. dawsont. In the
second specimen most of the crown has decayed, but the two
divergent roots are well displayed, the one somewhat stouter than
the other.

The third specimen is especially well preserved, and exhibits the
whole of the crown, as shown in the accompanying text-figure
(p. 279). It is a molar somewhat longer than wide, with nearly
parallel sides and one end truncated a little obliquely, while the other
is gently rounded : its total length does not exceed 2 millimetres.
The crown is covered with dense smooth enamel, without any traces
of wear, and so displays the exact shape and proportions of all the
cusps. It is marked by a median longitudinal depression, which
widens into a narrow flattened lip at the rounded end. On either
side of the median depression is a row of three blunt eusps, of
which those at the apparently internal border are the higher.
The latter cusps are obtusely conical, the two at the rounded end
being in close connexion, while the third at the truncated end is
somewhat larger and well separated from the others by a cleft.
The low external cusps approach a transversely-crescentic shape,

1 ‘On a Mammalian Tooth from the Wealden Formation of Hastings’ Proce,
Zool. Soc. 1891 (1892) pp. 585-86. A tooth of doubtful origin was subse-
quently described by Mr. R. Lydekker, ‘On a Mammalian Incisor from the
Wealden of Hastings’ Q. J. G. 8. vol. xlix (1893) pp. 281, 282.

PSS Pe ee -

Vol. 67.| TEETH FROM THE WEALDEN OF HASTINGS. 279

and that at the rounded end is much the larger—not extending
quite to the edge of the tooth, though occupying nearly half the
length of the crown. The other two external cusps are almost
equal in size, and are followed at the truncated border by a low
transverse ridge, which thickens within the last external crescent
and passes up nearly to the apex of the largest internal cusp.
There is no trace of a cingulum along either the internal or the
external border. The roots of the tooth are not exposed.

Dipriodon valdensis, sp. nov. ; crown of molar tooth, upper (A),
outer (B), and terminal (C) views, 15 times nat. size.

[Discovered by M. P. Teilhard de Chardin in the Ashdown Sands,
. Fairlight Cliffs, Hastings. |

This very small dental crown evidently belongs to one of the
Multituberculata (or Allotheria), but its black shining enamel
differs considerably in appearance from the paler coloured and
faintly-cracked enamel of the other Wealden teeth which have
been provisionally referred to Plagiaulaw. It is also distinguished
from the molars of the typical species of that genus by the arrange-
ment and shape of the coronal cusps. These cusps spread far towards
the middle of the tooth, and most of them, if much worn, would
exhibit a erescentic shape; whereas the cusps in a corresponding
molar of Plagiaulaw are more closely confined to the raised marginal
rim, and would not at any stage of wear expose a crescentic section.
The new Wealden tooth must therefore be assigned to one of the
so-called ‘ selenodont’ Multituberculata, of which the Lower Jurassic
Stereognathus* and the Upper Cretaceous Meniscoessus and Selena-
codon are typical examples.” Some of the teeth of this group bear
three, others only two rows of cusps; and it seems likely that
animals with 3-ridged molars in one jaw would have 2-ridged

1 R. Owen, ‘ Monograph of the Fossil Mammalia of the Mesozoic Formations ”
(Paleont. Soc. 1871) p. 18 & pl. i, figs. 27-30.
. 2 See especially O. C. Marsh, ‘ Discovery of Cretaceous Mammalia’ Amer.
Journ. Sci. ser. 3, vol. xxxviii (1889) p. 86 & pl. ii.

Q.J.G.8. No. 266. U

280 DR. A. S. WOODWARD ON SOME MAMMALIAN [May rort,
°

molars opposed to them in the other jaw. The generic determina-
tion of isolated teeth is thus impossible, until a series of complete
jaws has been discovered; but, as molars with a double row of
crescentic cusps have already been noticed by Marsh! as species
of ‘ Dipriodon,’ it is perhaps convenient to use this appropriately-
descriptive name also for the new tooth now described. It repre-
sents a very much smaller species than either of those from the
Upper Cretaceous of Wyoming named by Marsh, while the cusps of
the dental crown are less regular in size and arrangement than in
the latter. For purposes of reference the tooth may, therefore, be
recorded under the name of Dipriodon valdensis.

DIScUssION,

Mr. C. Dawson thanked the Author for his kind encouragement
and readiness at all times to assist in the determination of his
specimens, and remarked that in the English Wealden there are
three horizons where bone-beds constantly occur, namely :—(1) In
the Upper Tunbridge Wells Sands, just below the Weald Clay
(being the true ‘ Tilgate Grit’ of Mantell); (2) at a great depth
below the former, at the base of the Wadhurst Clay, in the blue
clay above, and sometimes associated with, the thick bed of cal-
careous sandstone (‘ Blue Stone’); and (3) about 26 feet below
No. 2 (at Hastings), at the top of the Ashdown Sand: it is less
fossiliferous than either of the former, and is usually associated
with bands of calcareous sandstone. So far, mammalian remains
had not been discovered in No.1: Nos. 2 & 3 had yielded the
teeth ascribed to Plagiaulax, and now No. 3 had also furnished
Dipriodon.,

During the last twenty years the speaker had disintegrated and
microscopically examined many tons of Beds 2 & 3; and during the
last two years he had been favoured with the patient and skilled
assistance of MM. P. Teilhard de Chardin and Félix Pelletier, to
whom the discovery of the multituberculate tooth (Dipriodon) was
due, as well as several new forms not mammalian. He was glad
to be able to say that, by the kindness of his colleagues, all these
Specimens are to be ceded to the British Museum.

Prof. W. Boyp Dawxtns, after an allusion to his find, in years
gone by, of Hypsiprymnopsis rheticus, expressed his pleasure that
the bone-beds of the Wealden were being worked at steadily : there
was a most wonderful development of these bone-beds in the
neighbourhood of Battle. He hardly thought that the affinities of
the mammalian teeth now described were with the Monotremes
(Prototheria), but rather with the Marsupials (Metatheria). It was
remarkable to find in the Eocene of both the European and the
American continents so specialized a type as Plagiaulax ranging
through from the Purbeck.

Dr. Henry Woopwarp bore testimony to the valuable services

1 Op. cit. p. 85 & pl. ii, figs. 13-18.

Vol. 67.) TEETH FROM THE WHALDEN OF HASTINGS. 281

rendered to paleontology by Mr. Charles Dawson, during more than
twenty years, in the Wealden formation of Sussex. .He commenced
his work by obtaining a large series of excellent IJguanodon
remains, now in the British Museum; but, of late, he had devoted
his attention to the discovery of minute mammalian teeth. These
Multituberculata were a most ancient and widespread type; indeed,
Tritylodon, from the Trias of South Africa (now considered a Therio-
dont reptile), was described in 1884 as a primitive mammal by
Owen. Charles Moore found Microlestes in the Rheetic, and Prof.
Boyd Dawkins Hypsiprymnopsis at Frome; Beckles found many
species in the Purbeck of Swanage, and so too Marsh in the
Jurassic and Cretaceous of America; while Cope added the Eocene
Polymastodon from New Mexico, and Neoplagiaulax had been added
in France.

The AvrHor, in reply, said he thought that, as the molars of
Plagiaulax closely resembled the temporary teeth of the recent
Ornithorhynchus, there was still reason to consider the Jurassic
genus as Monotreme rather than Marsupial. The new teeth which
he had described were essentially Jurassic in type, and so agreed
-with all the other vertebrates and fare found in the Wealden
formation.

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SAY MEE Sy RY e

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Proceedings of the Geological Society, Session 1910-11, including the Pro-
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PAPERS READ.
Page
5. Mr. H. H. Thomas on the Skomer Volcanic Series. (Plate X1).............65 wiltd
6. Miss G. R. Watney & Miss E. G. Welch on the Salopian Rocks of Cautley
and “Ravenstonedale. (Plate, X11)... ... co.cc cceocsncescostensosian eee 215
7. Mr. A. Wade on the Eastern Desert of Egypt. (Plates XIII-XV]) ......... 238
8. Mr. G. E. Dibley on the Teeth of Ptychodus and their Distribution in the
Hnglish Chalk. (Plates KVII-X XID)... 0c. cece ueewovsnnctciocasare eee 263
9. Dr. A. S. Woodward on some Mammalian Teeth from the Wealden of
BED aeCA BO Se aee acc os lesa cine de Now ena cunt une anesthe les Oe@b teen ee eeae ee eae 278

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Vol. LX VII. AUGUST 3lsr, 1911. No. 267.
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Vol. 67.] TEETH FROM THE WEALDEN OF HASTINGS. 281

rendered to paleontology by Mr. Charles Dawson, during more than
twenty years, in the Wealden formation of Sussex. He commenced
his work by obtaining a large series of excellent Jguanodon
remains, now in the British Museum; but, of late, he had devoted
his attention to the discovery of minute mammalian teeth. ‘These
Multituberculata were a most ancient and widespread type; indeed,
Tritylodon, trom the Trias of South Africa (now considered a Therio-
dont reptile), was described in 1884 as a primitive mammal by
Owen. Charles Moore found Microlestes in the Rheetic, and Prof.
Boyd Dawkins Hypsiprymnopsis at Frome; Beckles found many
species in the Purbeck of Swanage, and so too Marsh in the
Jurassic and Cretaceous of America; while Cope added the Eocene °
Polymastodon from New Mexico, and Neoplagiaulax had been added
in France.

The AvrHor, in reply, said he thought that, as the molars of
Plagiaulax closely resembled the temporary teeth of the recent
Ornithorhynchus, there was still reason to consider the Jurassic
genus as Monotreme rather than Marsupial. The new teeth which
he had described were essentially Jurassic in type, and so agreed
with all the other vertebrates and plants found in the Wealden
formation.

ee J. GS. Not 26. x

282 MR. E. S. COBBOLD ON TRILOBITES [Aug. 1911,

10. Trinopites from the PARADOXIDES Brps of Cominy (SHRop-
SHIRE). By Epear Srerztine Cosporp, F.G.S. With Norss
on some of the AssoctarED Bracutopopa, by CHARLES ALFRED
Marttry, D.Sc., F.G.8. (Read April 5th, 1911.)

[Pirates XXITI-XXVI_|

Introductory Remarks.

In a previous communication * I called attention to certain trilobites
associated with Callavia® callavec Lapw., from the limestones at
the top of the Lower Comley Sandstone, and indicated the
correspondence of many of the forms with those of Dr. Matthew’s
Protolenus Fauna from the Cambrian of the Atlantic province of
North America.

The object of the present paper is to describe and figure the
trilobites of the Upper Comley Sandstone, and to endeavour
to estimate the faunal importance of the phy sical break between the
upper and the lower groups of strata.

Many of the specimens have been obtained during the progress
of the excavations that I have been conducting for the British
Association ; others have been collected at various times during the
past twenty years; and, through the kindness of Prof. Charles
Lapworth, I have had access to the type-specimens of his Para-
doxides groomi, which are now figured for the first time.

The fossils described in this paper occur at three distinct horizons.
A lower one, the Quarry-Ridge Grits, at the base of the Para-

dowides-bearing beds of the Comley Sandstone, where they rest.

unconformably upon the Protolenus and Callavia Beds; a second,
the Hill-House Beds, some 300 feet higher in the succession; and a
third, the Shoot-Rough-Road Beds, near the top of the Comley
Sandstone Group, presumably several hundreds of feet higher.

The stratigraphical relations of these beds to one another and to
the strata above and below them, the local names adopted, and the
horizons from which the principal fossils have been collected, are
shown in the vertical section published in my report to the British
Association Committee for the Excavation of Critical Sections in the
Palzozoic Rocks of Wales & the West of England.’

1 Q. J. G. 8. vol. Ixvi (1910) pp. 19-51 & pls. iii-viii.

2 See Smithsonian Mise. Coll. vol. liii, No. 1934 (Aug. 1910), where
Dr. Walcott adopts Dr. Matthew’s term Callavia as a distinct generic name
for O. (Holmia) broggeri, O. (Holmia) callavei, and other species (pp. 274
et seqq.).

> Rep. Brit. Assoc. 1910 (Sheffield) p. 121.

Te

x

Vol: 67. ] FROM THE PARADOXIDES BEDS OF COMLEY. 283

Synopsis oF PART OF THE Camprtan Rocks or Comipy, snowing THE PosITIONS
or tae Fosstnirerots Horizons (in descending order).
Shoot-Rough- | Shale. Orthis (Orusia) cf. lenticularis Wahl),

Road < Gritty flags. Davidis Fauna.
|
Beds. \ Sandstone. Paradoxides rugulosus Corda,

Unexplored interval.

( Shale.
oases 4 Grits. Ptychoparia (Liostracus) sp.
ne ( Calcareous flags. Dorypyge lakei, sp. nov.

Quarry-Ridge { Shale.
Beds. Coarse gritand conglomerate. Grooimiti Fauna.

Unconformity and position of the Black Limestone.

{ The Grey Limestones.
Lower Comley | The Olenellus Limestone.

Sa ae | Sandstone, with occasional
{calcareous bands.

| Protolenus-Callavia Fauna.

_ Description of the Trilobites.

Paradoxides Brongniart.

ParapoxipEs GRoomit Lapworth. (PI. XXIII.)
C. Lapworth, Geol. Mag. dec. iii, vol. vii (1891) p. 532, footnote.

In the above-cited paper on Olenellus callavet, Prof. Lapworth
gives the following preliminary description of Paradoaides groomi :—

‘In general form and size intermediate between Par. Harlani (Green) and

| Par. Davidis (Salter). Length 8 to 9 inches, breadth 53. Head semicircular,
with pointed genal spines from 2 to 3 inches in length. Glabella pro-

minent, clavate, more than half its length being occupied by the broadly

rounded and smooth frontal lobe. Hypostoma of the type of that of Par.
Bohemicus (Boeck). Pleurse (No. ?) faleate, and sharply pointed. Pygidium

a raised disc with a central tubercle; embraced laterally by long, sabre-like,
distally-diverging spines. Localities—Neves Castle (Lapwerth, 1889) and

: Comley (Groom, 1890). Named after 'T. Theo. Groom, Esq., B.Sc., who first

collected fragments sufficient for description.’ (Op. cit. pp. 532-38.)

The type-specimens sent to me by Prof. Lapworth are to be found
upon four slabs of calcareous conglomerate from Comley Quarry,
lettered A, B, C, & D, and one piece of a rather different rock from
Neves Castle. Upon the slabs from Comley there are, also, several
examples of cranidia and pygidia of Dorypyge lakei, sp. nov.
(described below, p. 287), and also two of a long, tapering Hyo-
lithoid shell of circular section, which I recognize as being identical
with other specimens that I have collected from the same locality
and bed.

The fossil fragments in.the conglomerate of Comley Quarry
usually occur matted together in clots of calcareous material about

x2

284 MR. E. 8. COBBOLD ON TRILOBITES [Aug."Ten

1 foot above the actual base of the conglomeratic Quarry-Ridge
Grits. In some cases these clots pass by insensible gradations
into the glauconitic sandy matrix, in others they have sharp
boundaries as though they were included blocks of pre-existing
rock; but it is possible to collect specimens of the clots with a
well-defined boundary on one side, while on the other the calcareous
material passes gradually into the sandy matrix. The fossils of
the clots, which include Dorypyge, Conocoryphe, Stenotheca, and
the Hyolithoid shell, in addition to the fragments of Paradoawides,
are also found sporadically in the sandy matrix. Jam, therefore,
confident that the calcareous clots are of the same geological
age as the deposition of the grits.

Curiously enough, side by side with these calcareous clots,
fragments of limestone are to be found, containing recognizable
portions of trilobites of the Protolenus-Callavia Fauna and derived
from the underlying Lower Comley Sandstone.

In addition to the type-specimens, a great number of fragments
have passed through my hands, but only two of these throw
additional light upon the species. These are portions of thoracic
segments which fell to the hammer of Mr. W. G. Fearnsides on a
recent visit to the locality, and one part of a pygidium which I
uncovered on Slab A in trying to develop the margin of the
glabella.

Specimen [1307] * (Pl. XXIII, fig. 6) shows that the axial lobe
Was narrow as compared with the total width of the thorax
(apparently the proportion is only a fifth), and that it had a very
slight convexity. A second fragment [1308] (Pl. XXIII, fig. 3)
appears to belong to the posterior part of the thorax, where the
falcate extremity is curved backwards to a much greater degree
than obtains in [1307] or in [B.,] (fig. 7).

The fragment of a pygidium [A,] (Pl. XXIII, fig. 9), taken in
conjunction with [A,] (not figured), shows that the shield was of
the same rounded type as those of Paradoxides bohemicus Boeck
and P. tessini L.

The more noticeable features of the species, so far as at present
known, are (1) the general flatness of the whole shield; (2) the
width and slight convexity of the margin of the free cheek and,
by infereuce, of the whole margin of the head-shield; (3) the
pronounced smoothness of the upper surface; (4) the rugosities
of the doublure; and (5) the comparative narrowness of the
axial lobe.

The species seems to be most nearly related to Paradoxides regina
Matthew, which is described as an ‘unusually smooth species’
(op. cit. p. 120), but has ‘ obscure, scattered tubercles’ on the
cranidium, which are not seen in the specimens from Comley. The

1 [The numbers and letters in square brackets are those attached to the
specimens. Where numbers alone occur, the specimens are in my collection
for the Geological Excavations Committee of the British Association.—Z S. C.]

2 Trans. Roy. Soc. Canada, vol. v (1887-88) sect. iv, p. 119 & pl. iti.

Vol. 67.| FROM THE PARADOXIDES BEDS OF COMLEY. 285

rugosities on the doublure appear from Dr. Matthew’s figure to
correspond in spacing and number with those seen in the Comley
species, and the anterior marginal fold is wide and of little con-
vexity in both.

They are sufficiently differentiated by the course of the facial
suture posterior to the eye. In Paradowides regina it is distinctly
sigmoidal and extends widely outwards. In P. groomi it extends
but little beyond the eye (see Pl. XXIII, fig. 4), and in this
respect it approaches more nearly to P. bennettii Salter.’

The hypostoma of P. groom differs from that of P. regina in
being proportionately wider across the posterior part, and in being
furnished with hooks at the postero-lateral angles.

The fragments from Comley indicate a length of from 20 to 25
centimetres for the complete trilobite, which is about half the
length of Dr. Matthew’s type-specimen, and of very much the same
size as Salter’s.

Locality and horizon.—Comley Quarry, from the conglo-
meratic base of the Quarry-Ridge Grits; also from Neves Castle
(Lapworth).

PaRapoxIDEs spp. indet. (PI. XXIV, figs. 1-7 c.)

From some detached blocks of the material that has yielded the
Dorypyge and Conocoryphe described below, I have before me a
number of fragments of smaller Parudoxides, which indicate two
or three distinct species.

Locality and horizon.—Comley Quarry, from the conglo-
meratic portion of the Quarry-Ridge Grits.

PaRaDoxiDeEs Davipis Salter. (Pl. XXIV, figs. 17 a, 17 6, & 18.)

J. W. Salter, Q. J. G.S. vol. xx (1864) p. 234 & pl. xiii, figs. 1-2; and Mem.
Geol. Surv. dec. xi (1864) pl. x.

My collection contains many fragments of head-shields, pleure,
etc., which agree with Salter’s species, but do not indicate very
large examples of it. The reference is confirmed by the two pygidia
(319, 321] which are figured.

The larger specimen (fig. 17) appears to me to be of the normal
form, but the smaller (fig. 18) differs slightly in the shape of the
posterior margin between the two points and in the contour of
the sides. As has been suggested to me by Mr. Lake, it may be the
pygidium of a young individual of the species.

Locality and horizon.—The upper section on the Shoot-
Rough Road, Comley, about 400 yards north-east of the Quarry ;
from the ochreous band about 4 feet below the top of the Shoot-
Rough-Road Flags.

1 Q. J. G.S. vol. xv (1859) p. 583, text-figure.

236 MR. E. S. COBBOLD ON TRILOBITES (Aug. IgIt,

PaRaDoxIDEs RUGULOsUS Corda. (PI. XXIV, figs. 14-16 ae

I. Hawle & A. J. C. Corda, ‘ Prodr. Monogr. Bohm. Trilob.’ 1847, p
J. Barrande, ‘Syst. Silur. Bohéme’ vol. i (1852) p. 374, pl. ix, fig. 31 Seal xl,
figs. 3- 9, and Suppl. 1872, p. 11, pl. i, fig. 36.

This species is represented by a number of cranidia and other
fragments, usually in the state of very friable casts in rottenstone.
These are in accord with Barrande’s figures and descriptions in all
points, except that the rugosities on the anterior lobe and sides of
the glabella appear to be more strongly pronounced (see P]. XXIV,
figs. loa & 155).

al was so much impressed with these rugosities, that I sent the
specimen figured to Dr. G. F. Matthew, with the inquiry whether
it was related at ali closely to the Acadian P. lamellatus Hartt.
He very kindly replied that the rugosities of the Shropshire form
differ from those of P. lamellatus in being ‘ shorter, lower, and
more numerous.’

The pygidium (figs. 16 a-16¢) appears to me to be of the same
form as those from Bohemia. Dr. Matthew adds that a complete
eranidium, of which I sent him a drawing, ‘is a very good
eteminicus or rugulosus, but that the pygidium is not like that of
the Acadian P. eteminicus.

Locality and horizon.—Excavation No, 23 in a field near
the upper section on the Shoot-Rough Road, Comley; from a cal-
careous band at the summit of the Shoot-Rough-Road Sandstone,
about 14 feet below the band which yielded Paradowxides davidis
and the associated brachiopoda.

Conocoryphe Corda.

ConocoRYPHE EMARGINATA Linnarsson, var. LONGIFRONS, Noy.
(Pl. XXIV, figs. 8-13.)
J. G. O. Linnarsson, 1876-77, Geol. Foren. Stockholm Forhandl. vol. ii, p. 366,
& pl. xv, figs. 2 a—4.

In my collection there are fragments of several head-shields of a
trilobite, which seems nearly allied to Linnarsson’s species from
Stora Fro, but whether it should be regarded as a local variety or
as a distinct species, must depend upon the weight given to the
several divergences, which are as follows :—

(1) The Comley cranidia are longer, more convex, and more
quadrate in outline than the Scandinavian form. In the former
the facial sutures converge but gently forwards, whereas in the
latter they are inclined at a considerable angle to the axial line.

(2) The glabellas from Comley are long, strongly elevated and
somewhat campanulate in outline, and have only very faint traces
of the lateral furrows, whereas Linnarsson’s fig. 2 a shows a com-
paratively-short, conical glabella with well-marked furrows.

(5) The marginal rim (and concurrently the intramarginal
furrow) of the Comley form varies somewhat. In some specimens
(Pl. XXIV, fig. 12a) it is only just marked off by a change of
curvature, in others (fig. 13) it is separated from the rest of the

Vol. 67.] | FROM THE PARADOXIDES BEDS OF COMLEY. 287

front by a distinct groove, but this is never so deep or wide as that
shown in Linnarsson’s fig. 2 b.

In the Comley form the axial furrow varies in the same manner
as the intramarginal furrow, but is never very strongly marked.

The Tesr appears to be very thick and strong, and shows minute
granulations on the outer surface with interspaces, which in
places sink to little pits, too ill-defined to be called puncte.
The internal casts (figs. 12 & 13) show, upon the glabella and
proximate parts of the cheek, closely-set granulations indicating
depressions on the interior of the shell; towards the postero-lateral
angles these become successively coarser and, in front of the mark
corresponding to the ocular ridge, they are much elongated and
arranged in waving, irregular, discontinuous lines radiating towards
the margin of the shell; in front of the glabella the granulations
gradually split up into shorter lengths.

Free cHeex: There are in my collection three specimens of free
cheeks which are associated with the cranidia, and probably belong
to the same species.

The peculiar fragment shown in Pl. XXIV, fig. 11, gives a view
of the under side. It shows a strong and considerably elongated
genal spine, at the base of which there is a fold or ridge, and from
this the doublure sinks into the matrix to follow the curvature of
the upper side. Fig. 10 shows a fragment of, probably, the upper
side. In both specimens the surface is finely granular.

Pyerpium (Pl. XXIV, figs. 9a-9c): On a specimen kindly lent
to me by Mr. H. C. Beasley is an incomplete external cast of a
pygidium, which agrees, so far as it goes, with Linnarsson’s fig. 4.
The convexity is very pronounced (fig. 9 5); the axis shows three
divisions, in addition to the articulating facet and the bluntly
rounded end; and the lateral lobe shows two well-marked furrows,
with a faint indication of a third.

Locality and horizon.—Comley Quarry; from the conglo-
meratic base of the Quarry-Ridge Grits.

Dorypyge Dames.

I have fragments of at least twenty head-shields and as many
pygidia which come under this genus, and were derived from the
two horizons which I call the Quarry-Ridge Grits and the
Hill-House Flags. The specimens from the former, although
fragmentary, are excellently preserved, while those from the latter
are very fragile casts.

DoryPyGE LAKEI, sp.nov. (Pl. XXV, figs. 1-8 & text-fig. on p. 291.)

I take as type-specimens the two head-shields lying side by side
[1163], figured to natural size (Pl. XXV, fig.2) These exhibit all
the parts of the cranidium, and consequently I am able to make
a complete restoration of it (Pl. XXV, figs. 1 a-1c).

288 MR. E. 8. COBBOLD ON TRILOBITES | Aug. 1911,

I dedicate this species to Mr. Philip Lake, who has so frequently
befriended me in my study of the Comley trilobites, and who first
pointed out to me the reference of these fossils to Dames’s genus.

Cranipium: General form.—lIrregularly pentagonal, with the
anterior border rounded in front of the glabella, but nearly straight
in its continuation towards the sides.

Size.—Moderate; length of the type-specimens = about 8 milli-
metres, exclusive of the spine; width, across the eye-lobes = about
10 mm., across the posterior angles = about 11 mm. Other specimens
indicate lengths varying from 24 to 20 mm., exclusive of the spine.’

General convexity.—Very strongly marked, about 1: 2.4? in
the type-specimens, about 1:3 in others.

Glabella.—Strongly convex, both transversely and longi-
tudinally ; distinct from the occipital ring; about five-sixths of
the total length of the shield, exclusive of the spine; the sides are
nearly straight, and converge more or less rapidly backwards; the
width of the most convergent glabella at the anterior third is
about three-quarters of the length of the glabella, while at the
posterior end it is not much more than half that length; there is
no trace of any furrow to be seen, unless it be the little pit on the
line of the axial furrow, and a modification of the surface-markings,
mentioned below.

Occipital furrow.—Well defined; rather narrow, and fairly
uniform, in both width and depth, throughout; very straight in
its course, but, when viewed from above, it appears to be slightly
curved backwards by reason of the convexity of the glabella.

Occipital ring.—Of equal width with the base of the glabella ;
slightly broader in the middle than at the sides; armed with a
short, sharp, and slightly curved spine, which rises from the
posterior half of the ring, and is directed upwards and backwards ;
the ring is arched upwards very strongly as viewed from behind,
and must have accommodated a very convex thoracic axis.

Axial furrow.—tThe glabella is very distinctly outlined by
the change of curvature all round, but the furrow is scarcely at all
impressed, except near the anterior ends of the sides of the glabella,
where it sinks to a very distinct pit, which is impressed from the
side rather than vertically downwards, and may represent one of
the glabellar furrows (see P]. XXV, figs. 1 & 5).

Fixed cheeks.—Triangular in the view from above; convex ;
nearly horizontal close to the glabella, but curving down rapidly
to the eye-lobe and also both forwards and backwards.

EKye-lobe.—Small, about a sixth of the total length of the
head-shield ; at a low level as compared with the cheek, from
which it projects horizontally ; not raised at the edge; situated
about midway in the length of the cranidium.

Ocular ridge.—Obsolete.

' The size of the largest head-shield collected points to a total length, in the
complete trilobite, of 60 to 70 millimetres.

2 These numerals represent the proportion of the height of the shield to its
width.

Vol. 67.] FROM THE PARADOXIDES BEDS OF COMLEY. 289

Postero-lateral margin.—Consisting of a narrow convex
rim and a wide, well-rounded groove between it and the cheek ;
near the glabella the limb is almost horizontal, but farther out it
curves evenly and rapidly down to the postero-lateral angle, without
any decided point of geniculation.

Front.—Consisting of a very narrow convex border in front,
widening somewhat outwards, and having a rather wide groove in
its rear.

Facial suture.—Anterior branch, as seen from above (Pl. XXV,
fig. 1 a), convergent forwards and very short ; as seen from the side
(fig. 16) considerably longer and curved down to the groove
inside the marginal rim, beyond which it cuts the rim almost
horizontally. Posterior branch, as seen from above (fig. 1),
divergent and nearly straight to the postero-lateral angle, which is
situated distinctly farther out than the eye-lobe; as seen from the
side (fig. 16), this branch is somewhat sigmoidal and rather long.
The two branches of the suture, as seen from above, are almost
in one straight line from the anterior to the posterior angles ; but, if
the cranidium were flattened out, or had lost its great convexity,
the posterior branch would have a wide outward extension.

Test.—The whole of the outside of the head-shield is thickly
covered with short, irregular, subparallel, raised lines (PI-XXV,
fig-5). These lines are longer on the front of the glabella than
on its posterior part; on the cheeks they are much shorter ; while on
the frontal rim they are considerably elongated. It is Just possible
to detect interruptions of the rugose markings at the sides of the
glabella where the lateral furrows would occur. The cheeks, taken
alone, might be described as granular ; but there is a distinct grada-
tion in the surface-characters from one part of the shell to another.

In order to indicate the variations in size and in the shape of the
glabella, three additional figures (figs. 3, 4, & 5), drawn to the same
scale as the restoration of the cranidium, are given.

Free cHEEK: One very imperfect fragment of a free cheek
from the Hill-House Flags shows that it bore a strong rounded
spine at the genal angle, set so as to project horizontally outwards
in agreement with the spines on the pleure and pygidium.

THorsx: I have five or six specimens showing the pleure ; of
these two of the most complete are illustrated (Pl. XXV, figs. 6 & 7).
They consist, longitudinally, of three parts: a horizontal proximate
part, an inclined median part, and a distal spine that is nearly
horizontal. The length of the spine is about equal to that of the
proximal part, while that* of the median part is rather less. The
pleure have a well-rounded groove occupying one-half of the total
width.

Pyeipium (Pl. XXV, figs. 8a—S8c): Size.—Moderate; length,
exclusive of the spines, = 8 millimetres, greatest width = about
1] mm.

General form.—Sub-semicircular, with a strongly convex axis,
convex side-lobes, and a flattened, horizontal, spinose border.

General convexity.—-About 1: 3.5.

290 . MR. E. S. COBBOLD ON TRILOBITES (Aug. 1911,

Axial lobe.—Strongly convex in cross-section, and considerably
curved longitudinally; slightly narrowing posteriorly; greatest
width equal to about a third of that of the pygidium; divided by
six deep and wide furrows into an anterior, articulating facet,
and six other segments of subequal breadth: of these, the five
anterior are provided with short, strong, and straight spines pro-
jecting upwards and backwards; the sixth or terminal segment
has a well-marked node in place of a spine, and ends in a steep
slope down to the flattened border of the shield.

Axial groove.—Very slightly marked along the sides of the
axis.

Lateral lobes.—Sub-triangular; evenly convex outwards; not
connected together behind the axis; each lobe consists of six ribs ;
the anterior rib is narrow and rounded; the next three are much
wider and have their surfaces flattened transversely to their length,
and indistinctly marked with a wide furrow; the two remaining
ribs are small, and only just discernible.

Border.—Horizontal, and continuous round the sides and end
of the pygidium; the width, exclusive of the spines, is about
a tenth of the length of the shield; the margin is armed with
six spines of flattened, oval section on each side. So far as can be
seen from the specimens, the length of these spines is sensibly the
same throughout, except, perhaps, in the case of the hindermost
pair, which have their bases slightly enlarged.

Test.—The outer surface of the most perfect specimen [181]
(Pl. XXV, fig. 8 a) is a little corroded, and exhibits a finely granular
surface. Other fragments [183, 184] have their surfaces thickly
covered with raised granules, all the way from the axis to the spines.
This granulation is somewhat more minute than that of the head-
shield, but may be regarded as a further modification of that of
the fixed cheeks.

The pygidia described are nearly allied to those of Dorypyge
orvens Gronwall,' but differ in certain respects. In his species the
two posterior marginal spines are much longer than the others, and
have enlarged bases to correspond ; they also diverge one from the
other: while those of the Comley pygidia are little, if at all, longer
than the rest, and project directly backwards in the line of the
axial furrows. To judge by the figures and restoration given by
Dr. Gronwall, the Bornholm species is somewhat narrower than the
Shropshire form, and the five anterior pairs of spines are, propor-
tionately, somewhat shorter.

The test of Dorypyge ortens is described as being smooth, while
that of D. lake: is decidedly granular, and the elabella is quite
rugose (see Pl. XXV, fig. 5). |

I have attempted a restoration in outline of this species (see
the accompanying text-figure, p. 291). The number of thoracic
segments (eight) is inserted from the analogy of other species. The

' K. A. Gronwall, Danmarks Geol. Underség. ser. 2, No. 13 (1902) pp. 185
& 216, pl. iii, figs. 13-15.

Vol. 67.] FROM THE PARADOXIDES BEDS OF COMLEY. 291

free cheeks and thoracic axis are based on the evidence supplied by
fragments from the Hill-House Beds. The axial spines are drawn
to agree with the two or three towards the end of the pygidium
seen in another specimen.

Side view and view from above of Dorypyge lakei, sp. nov. Restored

from fragments found at Comley (Shropshire): about three
tumes the natural size of the type-specimens,

ING OZ. |

Localities and horizons.—Comley Quarry, from the con-
‘glomeratic base of the Quarry-Ridge Grits; also from the Hill-
House Flags that lie under the little quarry at the northern end
‘of the ridge which bears that name; and again from the Quarry-
Ridge Grits of Robin’s Tump, Comley.

Agnostus Brongniart.

-Aencstus FALLAx Linnarsson, (Pl. XXV, figs. 17 a-18 6.)

J. G. O.. Linnarsson, ‘ Vestergétlands Cambr. & Silur. Aflagr.’ K. Svensk.
Vetensk.-Akad. Handl. n. s. vol. viii (1869-70) No. 2, p. 81 & pl. ii, figs. 54,
55; and Geol. Foren. Stockholm Forhandl. vol. iii (1876-77) p. 371 &

pl. xv, fig. 7.
This species is represented by the fragmentary head- and tail-
shields figured. I am indebted to Mr. Philip Lake for help in their

determination.

Locality and horizon.—The upper section on the Shoot-
Rough Road, Comley; from the ochreous band about 4 feet below
the top of the Shoot-Rough-Road Flags.

292 MR. E. S. COBBOLD ON TRILOBITES [ Aug. 191T,.

Microdiscus.

Micropiscvus sp., cf. M. punctatus Salt. (Pl. XXV, figs. 12 a-12¢.).-
J. W. Salter, Q. J. G. S. vol. xx (1864) p. 237 & pl. xiii, fig. 11.

The specimen [1297] exhibits five or more imperfect internal
casts of a minute form of pygidium, about 14 millimetres long, from
which I have compiled the outline sketches (Pl. XXV, figs. 125.
& 12¢). None of the specimens show the complete number of the
divisions of the axis, but I do not think that there could have been
more than seven or at most eight, including the articulating and
terminal portions. In this respect these pygidia differ from M. pune-
tatus Salter, and from the related forms M. scanicus and M. eucentrus
Linnarsson.*

Locality and horizon.—The upper section on the Shoot-
Rough Road, Comley; from the Shoot-Rough-Road Flags, 1 or 2:
feet below the ochreous band.

Agyraulos Corda.

AGRAULOS (?) HOLOCEPHALUS Matthew. (Pl. XXYV, figs. 9 all c.)

G. F. Matthew, Trans. Roy. Soc. Canada, vol. viii (1890-91) sect. iv, p. 1388 &
pl. x1, figs. 5 a-5 d.

Dr. Matthew’s species appears to be represented by several
cranidia, three of which [3860-362] are figured. The last (Pl. XXV,
fig. 9a) has been much flattened by pressure, but the smallest
(fig. 11 a) seems to retain its original convexity, which is very high
(about 1: 2.5).

The most convex specimen shows no sign of any marginal rim 3.
but this feature is slightly marked in the other two specimens.

Pyerpium ? (Pl. XXV, figs. 16 a-16c).—Associated in the same
rock with these head-shields are two specimens of pygidia |376,
378] which may possibly belong to this species; but, so far as.
association goes, they might equally be referred to one or other of
the two species next to be noticed.

Locality and horizon.—The upper section on the Shoot-
Rough Road, Comley; from the ochreous band, about 4 feet below
the top of the Shoot-Rough-Road Flags.

AGRAULOS sp., cf. A. QUADRANGULARIS (Whitfield), (Pl. XXV,
figs. 13, 14, & ?15.)
R. Pod, Bull. Amer. Mus. Nat. Hist. vol. i (1884-86) p. 147 & pl. xiv-
‘ g. 8.
C. D. Walcott, U.S. Geol. Surv. Bull. No. 10 (1884) p. 48 & pl. vii, fig. 1.
A second species, which is probably referable to Agraulos, is
indicated by specimens [869-371] from the same bed of rock as

1 J. G. O. Linnarsson, ‘ De undre Paradoxides Lagren vid Andrarum’ Svyer.
Geol. Undersokn. ser. C, No. 54 (1888) pp. 29 & 30, pl. ii, figs. 17-20.

yon, G7. FROM THE PARADOXIDES BEDS OF COMLEY. 293

those just described. They are, however, too imperfect to admit of
exact identification. .

Except for the marginal rim, which at best is but poorly defined,
this form is very near to Agraulos quadrangularis (Whitfield), as
figured by Dr. Walcott. The eye-lobe in the Comley form is
possibly a little larger than that shown in his figure, and the
front is somewhat less distinctly rounded. ‘The similarity in the
transverse view of the head with that of A. (?) holocephalus is
very marked.

Locality and horizon.—The upper section on the Shoot-
Kiough Road, Comley ; from the ochreous band, about 4 feet below
the top of the Shoot-Rough-Road Flags.

Ptychoparia Corda; subgenus Liostracus Angelin.

Mr. F, R. C. Reed,in his memoir on the Cambrian fossils of Spiti,"
gives a valuable summary of the views expressed by various
authors on the classification of the many forms that have been
placed under the genera Ptychoparia, Liostracus, and Conocephalites,
and finally adopts these three names as subgeneric terms.
Following this arrangement, I place the three or four forms next
to be described under the subgenus Liostracus.

PrycHoparta (LiosTRAcUS) PULCHELLA, sp. nov. (Pl. XXVI, figs.
1 a—2.)

Crantpium [353]: Size.—Moderate; length, exclusive of the
occipital spine = 8 millimetres; width, across the eye-lobes =
91 mm., across the posterior angles = 12 mm., in front of the
eyes = about 8 mm.

General form.—Trapezoidal, with well-rounded front; all
features in strong relief.

General convexity.—Considerable ; about 1: 4.

Glabella.—Truncate-conical, with broadly round apex ; strongly
convex; slightly curved longitudinally ; occupying about two-thirds
of the length of the head-shield, omitting the spine; width =
about a third of that across the eye-lobes ; without furrows.

Occipital furrow.—Distinct ; straight ; not deep.

Occipital ring.—Almost entirely merged into the base of a
sharp, pointed spine, which projects upwards and _ backwards,
reaches to a higher elevation than the glabella, and extends back to
a distance from the occipital furrow equal to about half the length
of the glabella.

Axial furrow.—Wide; and well marked, both at the sides and
at the apex of the glabella.

Fixed cheeks.—Gently and evenly convex in cross-section ;
most elevated about midway in the length of the head; falling
steeply to the postero-lateral furrows and gently forwards; con-
nected in advance of the glabella by the tumid part of the front.

1 Pal. Indica, ser. xv, vol. vii, Mem. No. 1 (1910) pp. 13-18.

294 MR. E. 8. COBBOLD ON TRILOBITES [ Avie Stones

Eye-lobes.—Rather small; about a sixth of the total length
of the head-shield without the spine, and situated a little behind
the middle of the length of the glabella; having the outer edge
distinctly raised, so that there is a hollow between it and the fixed
cheek.

Ocular ridge.—A slightly raised ridge, curving back from the
anterior ends of the sides of the glabella to the eye-lobe, near which
it loses prominence.

Postero-lateral border.—The furrow runs in a straight line
- with the occipital furrow transversely to the axis of the head-
shield; the fold widens considerably outwards, so that the actual
margin diverges considerably from the line of the furrow.

Front.—Extending forwards for a distance equal to about half
the length of the glabella and consisting of three subequal parts,
a convex swelling connecting the fixed cheeks; a wide, rounded
hollow, and a well marked, rounded marginal rim, which extends,
with very little loss of strength, to the facial sutures.

Facial suture.—Not completely preserved in any specimen ;
anterior branch curving gently inwards from the eye-lobe; posterior
branch diverging outwards at a gentle curve to the posterior
angles.

Trsr: Much weathered in all the specimens; but with indica-
tions of having been relatively thick (see Pl. XXVI, fig.16); surface—
characters unknown.

Free cureexs: There are several free cheeks [372, 374, 375]
to be seen on the same hand-specimens with the cranidia. They
agree with them in size, in the character of the weathered test and
in the contour of the rounded margin, which is prolonged backwards.
into a short spine of circular section. Specimen [372] (Pl. XXVI,.
fig. 2) shows the curves of the eye and of the facial suture, and I
have very little hesitation in referring it to the species. ‘The area
of the cheek is separated from the rounded margin by a distinct
hollow, and rises in a gentle convex curve to the place of the eye.

This species seems nearest to Liostracus validus Matthew, and it.
is also not far removed from L. linnarssoni Brogger ; but from both
it differs in the relative length of the glabella. The graceful curves.
of the cranidium suggest the specific name.

Locality and horizon.—The upper section on the Shoot-
Rough Road, Comley ; from the ochreous band near the top of the
Shoot-Rough-Road Flags.

Prycnoparia (Liosrracus) sp. indet. (Pl. XXVI, figs. 4a—4c.)

A form allied to Pt. (L.) pulchella occurs at a considerably lower
horizon, which I call the Hill-House Grits. The only specimens.
that J have seen are, however, badly preserved, and it is impossible
to give a detailed description of them.

As the figures show, this species or variety is less convex and
has a wider and longer glabella than Pt. (L.) pulchella, also the

Vol, 67.] FROM THE PARADOXIDES BEDS OF COMLEY, 295

spine, anterior border, and anterior marginal hollow are less strongly
developed. It would, moreover, appear to be a rather smaller form.

Locality and horizon.—The little quarry at the northern
end of the Hill-House ridge; from the coarse grits, both above and
below the, thick beds of compact grit.

Prycnorarta (Liosrracus) sp. indet. (Pl. XXVI, figs. 3a-3c.)

Another form which I refer to the subgenus is represented by
one imperfect external cast of a cranidium, preserved in a sandy
erit [1118]. It is principally remarkable for the great elevation
of the fixed cheeks, which are almost as high as the glabella, their
maximum altitude being situated towards the outer edge.

Locality and horizon.—The upper section on the Shoot-
Rough Road, Comley; from the main mass of the Shoot-Rough-
Road Flags, about 8 feet below their upper limit.

Prycnoparta (Liosrracts)? pusta, sp.nov. (Pl. XXV, figs. 19a—21.)

Several small heads in my collection from the same rock-bed as
Pt. (L.) pulchella, sp. nov., may possibly be young individuals, but
there are so many differences that [ am not quite sure that they
belong even tothe same genus. From Pt. (L.) pulchella they differ
in the following respects :—(1) The glabella is parallel-sided instead
of being truncate-conical; (2) there is no spine on the occipital ring;
(3) the eye-lobes are proportionately larger ; (4) the general con-
vexity is greater; (5) the space in front of the glabella is more
fully convex and, in consequence, the intramarginal hollow is narrow
and sharp. I think, therefore, Uae it is best to describe them in
full as a distinct species.

Craniplum: Size.—Minute ; length = from 24 to 34 millimetres.

General form.—Trapezoidal ; features in high relief.

General convexity.—High; about 1:3.

Glabella.—tConvex ; parallel-sided ; with rounded apex; dis-
tinct from the occipital ring; rather more than half the total length
of the shield; externally without furrows; but one specimen, an
interior [366 | (Pl. XXV, fig. 21), shows two pairs of furrows directed
somewhat backwards.

Occipital furrow.—Deeply impressed; continuous.

Occipital ring.—Convex ; with the posterior margin curved
backwards, almost semicircularly.

Axial furrows.—Very deeply impressed, both at the sides and
round the apex of the glabella.

Fixed cheeks.—Nearly as wide as the glabella; transversely
convex; continuous round the apex of the glabella, and of almost
equal elevation throughout ; widening out behind the eye-lobe, and
falling steeply into the groove of the postero-lateral border.

Eye-lobe.—About a quarter of the length of the head-shield;

296 - MR. E, §, COBBOLD ON TRILOBITES | Aug. 1911,

raised at the edge and situated about midway in the length of the
shield.

Ocular ridge.—Distinct in the interior [366], fig. 21, but
hardly visible in the other specimens.

Postero-lateral border.—Furrow narrow and _ strongly
marked ; fold convex and also narrow; the whole border, as seen
from behind, curves evenly down without geniculation to the lateral
angles, which extend farther out than the eye-lobes.

Front.—Consisting of the convex space which connects the
fixed cheeks and a convex marginal rim, separated by a deep,
distinct, and narrow furrow. When viewed from in front, the
marginal rim is very much arched upwards in the middle.

Facial suture.—Anterior branch, a little uncertain, apparently
convergent forwards from the eyes; posterior branch divergent
backwards.

Tnst: Imperfectly preserved.

Locality and horizon.—The upper section on the Shoot-
Rough Road, Comley; from the ochreous band, about 4 feet below
the top of the Shoot-Rough-Road Flags.

Faunal Grouping of the Trilobites.

The trilobites of the Comley Sandstone fall naturally into three
principal groups or faunas—an upper with Paradoxides davidis, a
median with P. groom, and a lower with Protolenus and Callavia.

When the fossils are collected carefully bed by bed, several minor
groups make their appearance, which, so far as can be judged from
my collection, are very distinct. The horizontal extent of the beds
available for examination is, however, so limited, that it is quite
possible that these differences may prove to be more apparent than
real.

Tap FaunaL Groups oF THE CoMLEY SANDSTONE IN DESCENDING
ORDER OF OCCURRENCE.

Davipis Fauna.—Shoot-Rough-Road Flags.

Paradoxides davidis Salter. Piychoparia (Liostracus) pulchella,

Agnostus fallax Linnarsson. sp. nov.

Agraulos holocephalus Matthew. Ptychoparia (Liostracus) sp. indet.

Agraulos sp., ct. Arionellus quadran- | Ptychoparia (Liostracus) ¢ dubia, sp.
gularis Whitfield. nov.

Microdiscus sp., cf. M. punctatus Salt.

Brachiopoda (identified by Dr. Matley) :—

Lingulella cf. L. ferruginea Salter. Acrotreta aff. A. socialis von Seebach.
Lingulella (9) sp. indet. [1633]. Billingsella lindstremi Linnarsson,
Lngulella (2) sp. indet. |709-710]. var. salopiensis, nov.

Acrothele cf. A. granulata Linnarsson. | Bil/lingsella cobboldi, sp. nov.
Acrotreta(Linnarssonia) sagittalisSalt. | Orthis (o) sp:

Vol. 67.] FROM THE PARADOXIDES BEDS OF COMLEY. 297
A minor group, which is perhaps separable from the Davidis Fauna.
Shoot-Rough-Road Sandstone.

Paradoxides rugulosus Corda.
Brachiopoda (identified by Dr. Matley) :—

Lingulella ct. L. ferruginea Salter.
Lingulella (2) sp. indet. [1071, 1072].

A wide interval of unexplored ground, probably representing a thickness of
several hundreds of feet of strata, intervenes between the Shoot-Rough-Road
Beds and the next lower horizon known.

A minor group, which is perhaps separable from the Groomzi fauna below.
Hill-House Beds.
Dorypyge lakei, sp. nov.
Ptycheparia (Inostracus) sp. indet., allied to Pt. (L.) pulchella, sp. nov.
Acrotreta aud Hyolithellus, awaiting critical determination.

Groomm FaunA.—Quarry-Ridge Grits.

Paradoxides groomii Lapworth. - Conocoryphe emarginata Linnarsson,
Paradoxides sp. indet. No. 1. var. dongifrons, nov.

Paradoxides sp. indet. No. 2. Dorypyge laket, sp. nov.

Paradoxides sp. indet. No. 3. Stenotheca and Hyolithellus, awaiting

critical determination.

An unworked group or fauna.—The Black Limestone.

Prororenvs-Catravia Waunsa.—The Grey and Olenel/us Limestones.

Loratvs Group.—Upper portion of the Grey Limestone.

Microdiscus lobatus Hall. Mohicana clavata Cobbold.

Micrediscus comleyensis Cobbold. Protolenus latouchei Cobbold.

Microdiscus speciosus Ford. Protolenus morpheus Cobbold.

Anomocare platycephalum Cobbold. Lingulella (?), Kutorgina (?), Scen-

Anomocare parvum Cobboid. ella (?), Hyolithus, Hyolithellus, and

Agraulos (Strenuella) salopiensis Helenia (?) awaiting critical deter-
Cobbold. mination.

Mohicana lata Cobbold.

Briciuarcinatvs Group.—Lower portion of the Grey Limestone.

Microdiscus bellimarginatus 8S. & F. | Lingulella (2), Linnarssonia (?), Ku-

Anomocare (?) pustulatum Cobbold. | torgina (2), Obolus (?), Orthis (2),
Callavia cobboldi Raw MS. Hyolithellus, and Helenia (2?) await-
Callavia callavet Lapworth. | ing critical determination,

1 This species has been identified since the publication of my previous paper
on some small trilobites from Comley, Q. J. G.S.. vol. Ixvi (1910) pp. 19-51.

Q. J. G. S. No. 267. | Y

298 MR. E, S. COBBOLD ON TRILOBITES [Aug. rgrt,

Heiena Group.—The Olenellus Limestone.

Microdiscus helena Walcott. Callavia callavei Lapworth.
Micmacca(?) ellipsocephaloidesCobbold | Callavia cartlandi Raw MS.
Do. do. var. senior Cob- | Ptychoparia (2) attleborensis S. & F.
bold. Ptychoparia (?) annio Cobbold.
Do. do. var. strenuel- | Iphidea(?), Kutorgina(?), Lingula(?),
loides Cobbold. Linnarssonia (¢), Hyolithus, Hyo-
Do. do. var. sp?nosa Cob- lithellus, and Stenotheca, awaiting
bold. critical determination.

Micmacca (?) parvula Cobbold.

The generic references, particularly those in the lowest of the
three faunas, are more or less provisional, and will require careful
revision, before the divergences shown in the table between the
component groups of the Protolenus-Callavia Fauna are thoroughly
established. It may well be that further study of the forms, or
further work in the field, will bring them much closer together
than they seem to be at present.

As they now stand, there is no species of trilobite which passes
the higher of the two dividing-lines, and even the genera seem
entirely different. The lower dividing-line, according to my present
determinations from very fragmentary specimens, is crossed by one
important species, Callavia callavec Lapw. It seems probable that
some of the brachiopoda, Hyolithide, etc., will also be found to
pass the dividing lines, and so link up the three groups into one
fauna,

The divergence between the Protolenus-Callavia Fauna and the
Groomit Fauna is very complete. No genus among the trilobites *
passes from one to the other, and the forms of Stenotheca and
Hypolithellus that I have collected from the upper beds are quite
distinct from those of the lower.

This divergence of faunas is accompanied by a well-marked
unconformity to which I refer in more detail below ; but I would
again call attention to the Black Limestone of Comley Quarry,
which comes in between the Grey Limestones with Microdiscus
lobatus and the Quarry-Ridge Grits. It contains a group of fossils
(trilobites, Hyolithide, brachiopeda, etc.) that is, possibly, inter-
mediate between the Protolenus-Callavia and the Groomz Faunas.
The trilobites are, however, so fragmentary and so difficult of ex-
traction, that I am compelled to await the evidence afforded by
the other fossils, before I can indicate the relations of this band to
the strata above and below it.

The Unconformity.

The evidence for the unconformity between the Middle and the
Lower Cambrian of Comley formerly consisted in the included blocks
of the conglomeratic base of the Quarry-Ridge Grits, and in the

1 It must be noted that the genus Microdiscus reappears in the Davidis

Fauna, as in other regions. It is very doubtful whether the Ptychoparie (?) of
the Olenellus Limestone are properly referable to Corda’s genus.

Vol, 67.] FROM THE PARADOXIDES BEDS OF COMLEY, 299

change of faunas to which Prof. Lapworth called attention in 1891."
It has received conclusive corroboration from the excavations of
1909 and 1910 for the British Association * in the isolated hill called
Robin’s Tump, about half-a-mile south of Comley Quarry.

The basement deposits of the Middle Cambrian are now found
in contact with: (1) the Grey Limestones yielding Protolenus,
Strenuella, ete. (in the Quarry Ridge); (2) the Olenellus Limestone
yielding Callavia, etc. (in Dairy Hill) ; and (3) the underlying green
sandstones, some depth below their summit (in Robin’s Tump),
and in this last there is undoubted evidence that the contact is
due to unconformity.

The duration of the interval represented by the change of faunas
finds a parallel in the time required for the physical break. How
much of the life-history of this interval may be provided by the
fossils of the Black Limestone is a problem that remains to be worked
out.

General Conclusions.

(1) An unconformity occurs at the top of the Lower Cambrian
rocks of Comley, which trenches somewhat deeply into that series
and cuts out any upper members that may have existed.

(2) The highest of the Lower Cambrian beds at present known
yield what appear to be successive modifications of a fauna closely
allied to Dr. Matthew’s Protolenus Fauna, and characterized in part
by the presence of several members of the genus Callavia.

(3) Many of the trilobites of these beds are identical with, or
closely allied to, species which occur low down in the series in
America, and many hundreds of feet. below the horizon of the
Olenelli with the telson-like pygidia.

(4) Inferentially it appears probable that, if these Olenelli ever
existed in Shropshire, their’ place is among the beds which are
missing by reason of the unconformity.

(5) The beds (conglomerate and grits) immediately above the
unconformity contain several species of Paradowxides, and should
therefore be classed with the Middle Cambrian ; but the evidence
at present available is not sufficient to warrant a very close
correlation with any of the horizons of the typical sections of
Scandinavia.

(6) After passing a considerable interval of unexplored ground,
we find a series of gritty flags with a fauna characterized by
Paradoxides davidis and containing a number of brachiopods which,
taken together, indicate a high horizon in the Middle Cambrian.
These flags are succeeded above, with apparently complete con-
formity, by a series of shales in which occurs a form almost

1 Geol. Mag. dec. 3, vol. viii (1891) p. 5382.
2 Rep. Brit. Assoc. 1910 (Sheffield) pp. 118-22, and MS. Rep. Brit. Assoc,
1911 (Portsmouth).

¥Z

300 DR. C. A. MATLEY ON BRACHIOPODA [Aug. 1911,

identical with Orthis (Orusia) lenticularis Wahlenberg, suggesting
the incoming of an Upper Cambrian fauna.

(7) In close association with the flags yielding P. davidis, and
only a little lower in the sequence, a species of Puradoxides with
very elongated eye-lobes (P. rugulosus Corda) is found. It is
therefore unsafe to infer that a Paradoawides with a long eye-lobe
necessarily indicates a low horizon.

I hardly know how I can adequately express my indebtedness:
to Dr. Matley for all the trouble that he has taken in the identifi-
cation of the brachiopoda associated with Paradoaides davidis.
The specimens were numerous and indifferently preserved, and
consequently a very great demand upon his leisure was entailed in
order to go through them critically ; then too he has had a great
deal of tedious work in looking up the literature, and in writing
and revising his descriptions of the various forms. For all of this.
I am most grateful, and I consider that I have been ye fortunate
in having been favoured with his co-operation.

I am also indebted to Mr. Philip Lake for much help, especially
at the beginning of my studies of the Comley trilobites ; it was a
great advantage to me to have a safe road pointed out at the
starting-point, by one who had travelled far in the same direction.

To Mr. F. R. C. Reed and to Dr. G. F. Matthew my acknow-
ledgments are gratefully made for their kindness in replying to my
* enquiries ; and to Prof. Charles Lapworth there is an ever-increasing

debt, that I can never hope to repay, for his continued kindly

advice, encouragement and inspiration, in addition to his permission.
to publish my notes on his type-specimens of Paradoaides groomit.

APPENDIX.

Nores on some of the Bracuioropa from the Paradowxides-
Beds of Comley. By Dr. C. A. Mattery.

Class BRACHIOPODA.

Order ATREMATA Beecher.

Family Ozorrp# King (emend.).

Lineveza cf. rerRueiINeA Salter. (Pl. XXVI, figs. 5-60.)

1867. Cf. Lingulella ferruginea et var. ovalis Salter, Q. J. G. S. vol. xxii,
p- 340 & figs. 1-3.
1868 “ 1871. Cf. Lingulella ferruginea Davidson, Geol.} Mag. vol. v, p. 806 &
pl. xv, figs. 1-8; ‘ Monogr. Brit. Foss. Brach.’ (Pal. Soc.) vol. ili, p. 886 &
pl. xlix, fies, 32-35.

Vol. 67.] FROM THE PARADOXIDES BEDS OF COMLEY. 301

1876. Cf. Lingulella (?) sp. indet., Linnarsson, ‘ Brachiopoda of the Pava-

i... dowides Beds of Sweden’ Bihang K. Svensk. Vetensk.-Akad. Handl. vol. 11,
No. 12, p. 15 & pl. iti, figs. 27-28.

1883. Cf. Lingulella fervuginea Davidson, ‘Monogr. Brit. Foss. Brach.’ (Pal.
Soc.) vol. v, pl. xvii, fig. 35.

Shell .corneous, small, slightly convex, ovate; widest about a
third from the front, length about one and a half times the breadth ;
broadly rounded in front; sides tapering to the beak, which in the
pedicle-valve appears to have been acutely pointed. Numerous
concentric growth-lines. Pedicle-slit narrow.

Dimensions.—Length = 4 millimetres, breadth = 2 to 24 mm.

Locality and horizon.—The upper section on the Shoot-
Rough Road, Comley; from a band of the Shoot-Rough-Road
Flags with Paradoaides davidis, and also from a band with Para-
dowides rugulosus at the top of the Shoot-Rough-Road Sandstone.

Note.—Three examples of this small Lingulella have been
collected, and they agree fairly well with the Menevian species from
St. David’s, although the Shropshire form seems to be rather more
acuminate at the beak. The Lingulella (?) figured by Linnarsson
from the Paradowides-forchhammert strata of Sweden may be
identical.

LryeuLexta (?) spp. indet. (Pl. XXVI, figs. 7-8 d.)

An imperfect single valve (fig. 7) has been obtained, which differs
from the small Lingulella described above. It was found in the
lower section on the Shoot-Rough Road, Comley, in tne band ox
the Shoot-Rough- Road Flags yielding Billingsella lindstremi, var.
saloprensis. ‘The valve is nearly flat, the sides taper rapidly
towards the beak, which is not preserved but appears to have been
acuminate. The front is not preserved. Along the sides is a
raised flat border or flange, about 0°5 millimetre wide. The shell-
substance consists of several layers. The surface-ornamentation
is not preserved, and the inner layers are smooth, except for faint
indications of longitudinal striss on one of them. Muscular mark-
ings not shown. Length=10 millimetres or more ; width=6 mm.
| -Another form (figs. 8a & 86), about 3 mm. long, rather broad,
almost subpentagonal in outline, and possessing a concentrically
striate exterior, occurs in the Shoot-Rough-Road Flags of the
upper section, in association with Acrotreta aff. socialis. In shape
it resembles, but is much smaller than, Linnarsson’s Lingulella (?)
nathorste of the Olenellus-kjerulfi Zone at Andrarum in Scania.?

'~ Another undetermined lingulelloid shell, a small oval form, occurs
with Lingulella ef. ferruginea in the Paradoxides-rugulosus band of
the Shoot-Rough-Road Sandstone of Excavation No. 23.

' Bihang K. Svensk. Vetensk.-Akad. Handl. vol. iii (1875-76) No. 12, p. 15
& pl. iii, figs. 29-30.

302 - “DR. C. A. MATLEY ON BRACHIOPODA [Aug. rgrt,

Order NEOTREMATA Beecher.

Family Acrotretip® Schuchert.

AcrorHE.E cf. granvtata Linnarsson. (Pl. XXVI, figs. 9a & 96.)

1876. Acrothele granulata Linnarsson, op. jam cit. Bihang K. Svensk. Vetensk. =
Akad. Handl. vol. ii, No. 12, p. 24 & pl. iv, fig. 51 (and 52°).

1877 & 1883. Non A. granulata Swanston, App. to Proc. Belfast Nat. Field.
Club (‘Silurian Rocks of Co. Down *), pl. vii, fig. 20; and Davidson,
‘ Monogr. Brit. Foss. Brach.’ (Pal. Soc.) vol. v, p. 214 & pl. xvi, figs. 29-30.

1908. Acrothele (Redlichella) granulata, Walcott, Smithsonian Misc. Coll.
vol. lini, No. 1810, pp. 89-90.

The specimen figured [682] shows a partly-exfoliated fragment
of the posterior portion of the pedicle-valve. The outermost layer
where preserved shows under a strong lensa minute granulation,
which at a little distance from the margin is arranged in wavy and
irregular lines that cross the corrugations of growth at a very acute
but variable angle. Close to the margin these wavy lines become
more nearly parallel to the concentric lines of growth. The inner
layers are smooth, and are pierced in the neighbourhood of the apex
by the pedicle-tube. The valve when complete would be about
63 millimetres wide, this being also the width of another (complete)
valve from the same locality. Several more fragments showing the
beautiful ornamentation of this species have also been obtained.

The specimens, though agreeing generally with Linnarsson’s type
in shape, size, and granulated character of the ornamentation, differ
' from the Swedish form in haying the apex less excentric. In this
respect they approach the closely-allied A. corzacea Linnarsson,
of the Paradoxides-forchhammeri Zone. A. granulata is found in
Sweden in the P.-dlandicus Beds, and in Warwickshire in the Lower
Stockingford Beds (Purley Shales) near Nuneaton.’

Locality and horizon.—tThe upper section on the Shoot-
Rough Road, Comley; from the band of the Shoot-Rough-Road
Flags which yields Acrotreta aff. socoalis. A fragmentary specimen
[1116], showing similar granulated ornamentation, was obtained
trom the same flags of the lower section, in association with
Billingsella lindstroenn, var. saloprensis.

Acrotreta (Linnarssonia) sagirratis Salter. (Pl. XXVI, figs. 10a
& 100.)

1866. Obolella sagittalis and Discina lJabiosa Salter MS. Rep. Brit. Assoc.
1865 (Birmingham) p. 285.

1868 & 1871. Obolella sagittalis Davidson, Geol. Mag. vol. v, p. 309 & pl. xv,
figs. 17-24; ‘Monogr. Brit. Foss. Brach.’ (Pal. Soc.) vol. iii, p. 339 &}pl. 1
figs. 1-14.

For further references see C. D. Walcott, Proc. U.S. Nat. Mus. No. 1299,
vol. xxv (1903) p. 594.

Three examples of this species have been found in the lower section

1 C. Lapworth & others, ‘Geology of the Birmingham District’ Proc. Geol.
Assoc. vol. xv (1898-99) p. 346.

Vol. 67.] FROM THE PARADOXIDES BEDS OF COMLEY. 303

on the Shoot-Rough Road, Comley, in a band of the Shoot-Rough-
Road Flags, associated with Billingsella lindstremi, var. salopiensis.

Acrorrera aff. sootaAtis von Seebach. (Pl. XXVI, figs. 11 a-11 4,
12, & 13. a-13 [?7)
1865. Acrotreta socialis von Seebach, Zeitschr. Deutsch. Geol. Gesellsch.
vol. xvii, p. 341 & pl. viiia, figs. 14.
1903. Acrotreta socialis and cf. A. schmalensei Walcott, Proc. U. 8. Nat. Mus.
No. 1299, vol. xxv, pp. 699 & 597.

Numerous specimens of a small Acroéreta have been obtained
from the Shoot-Rough-Road Flags. The typical form has the
pedicle-valve moderately elevated; the apex (bearing a minute
foramen) excentric, but not overhanging the hinge-line; the false
area well-defined, and showing a distinct pedicle-furrow. The
surface is marked by growth-ridges, which in some specimens are
rugose. The interior shows an apical callosity of moderate size
with the foraminal tube well displayed. The brachial valve is
slightly convex, and bears internally a strong median ridge and well-
marked cardinal scars, with occasional traces of other scars.

This form agrees very well with the description of A. socialis,
as re-defined by Dr. Walcott from specimens obtained from the Para-
dowides-olandicus Zone of the Island of Borgholm (Sweden); but
eur specimens are somewhat smaller than his, and in dimensions
and in most other respects approximate very nearly to the form
from the Paradowides-forchhammert Zone of Sweden assigned by
Linnarsson also to von Seebach’s species, but since separated by
Dr. Walcott and described under the name of A. schmalenset.

Other forms of Acrotreta may possibly occur with the above, but
I have been unable to separate them satisfactorily.

Locality and horizon.—The upper section on the Shoot-
Rough Road, Comley ; from a gritty band of the Shoot-Rough-
Road Flags, 2 feet above the band containing Paradowides dav

Order PROTREMATA Beecher.

Family BrnuinespLiip® Schuchert.

BInLINGSELLA LINDSTREMI, var. SALOPIENSIS, nov. (PI. X XVI, figs. 14a
-17 ¢.)¥
1876. Cf. Orthis lindstremi Linnarsson, ‘ Brachiopoda of the Pavadowxides Beds
of Sweden’ Bihang K. Svensk. Vetensk.-Akad. Handl. vol. iii, No. 12, p. 10
& pl. i, figs. 1-8, pl. ii, figs. 9-12.
1905. Cf. Billingsella lindstroemi Walcott, Proc. U.S. Nat. Mus. No. 1395,
vol, xxviii, p. 238.

Shell biconvex, rotundo-subquadrate to subcircular in outline,
wider than long, broadest at about the middle, cardinal angles
rounded. The surface is covered with fine, rounded, radiating cost
increasing usually by interpolation, the interspaces being rounded
and of about the same width as the coste. Fine concentric,

304 DR. C. A. MATLEY ON BRACHIOPODA [Aug. 1911,

usually inconspicuous, ridges cross the ribbing, and at intervals are
more strongly marked. Forty to fifty, and sometimes even more,
coste may be counted around the margin of each valve.
Pedicle-valve moderately and uniformly convex, deeper than
the brachial valve. Beak small; cardinal area triangular, bent
away from the plane of the margin of the valve, and apparently
striated parallel to the hinge-line. Delthyrium open in the spe-
cimens examined.
In the interior of the pedicle-valve the hinge-teeth are supported
by dental plates which are continued to form a semicircular ridge
enclosing a large concentrically-ridged muscular area around the
umbo of the valve. This region is crossed by the vascular trunks
which extend from the umbo for about two-thirds of the length of
the valve. A low rounded elevation occupies the middle of the shell
between the vascular trunks, but is not noticeable on the exterior.
Brachial valve slightly convex, with a low median sinus
extending to the front. Beak small. Cardinal area narrow. A
low rounded mesial ridge in the interior of the valve bears at its
posterior extremity a simple rounded cardinal process. The widely-
separated and divergent crura are short and stout. No chilidium
appears to be present. ‘Two pairs of elongated muscular impres-
sions represent the places of attachment of the adductor muscle.
Dimensions.—The largest example collected (a brachial valve)
measures 8 millimetres in length by 11 mm. in width, but the
majority of the specimens average about 8 mm. in width.
Locality and horizon.—The lower section on the Shoot-
Rough Road, Comley. Abundant as internal and external casts in
a band of the Shoot-Rough-Road Flags, at or near the horizon of
Paradoxides davidis.
Observations.—This variety appears to differ from the form
described by Linnarsson from the Paradoxides-forchhammeri Zone of
Sweden in the following respects :—

(a) The pedicle-valve is always deeper than the brachial, whereas, according
to Linnarsson, the brachial valve of the Swedish form is the more convex.

(0) The ribbing is more regular, never exhibiting the wide interspaces
figured by Linnarsson ((oc. cit. pl. i. fig. 6c).

(c) The Shropshire form is smaller, the dimensions being about two-thirds
of those of the specimens described by Linnarsson.

In other respects the forms closely correspond.

The apparent absence of a deltidium makes the refgrence of this
form to the genus Billingsella somewhat doubtful, although with this
exception the species has all the essential features of the genotype
Orthis pepina Hall (= Orthis coloradoensis Shumard).

BILLINGSELLA LINDsTREMI Linnrs., var. (Pl. X XVI, figs. 18 a-19 6.)

A very similar form is found associated with the above-described
variety, but occurring less abundantly ; and it is also found at a
different section of the beds, which has not yielded the variety
salopiensis. It differs from the last-named variety only in the

Se

Vol. 67.] FROM THE P4ARADOXIDES BEDS OF COMLEY. 305

ribbing, the interspaces being occupied to a smaller extent by inter-
polated costa. In this respect it comes nearer to Linnarsson’s type
of the species.

Intermediate forms occur, connecting this variety with that which
I have named salopiensis.

Locality and horizon.—Both sections on the Shoot-Rough
Road, in the Shoot-Rough-Road Flags: in the lower section
associated with var. salopiensis and intermediate forms ; in the
upper section associated with Acrotreta aff. socialis.

BILLINGsELLA COBBOLDI, sp, nov. (Pl. XXVI, figs. 20 a—23.)

Shel] semicircular in outline, biconvex, nearly twice as wide as
long, widest at the hinge-line; cardinal angles rectangular, or nearly
so. Valves ornamented with about ten or twelve principal strong
rounded ribs. Additional ribs appear by interpolation at various
distances from the beaks, so that around the margin of each valve
some fifteen to eighteen ribs may generally be counted. Con-
centric lines of growth indent the ribs at close intervals.

Pedicle-valve gently convex, with a very slight depression
along the middle. Area narrow, with small delthyrium; beak in-
curved ; umbonal cavity small; hinge-teeth small, divergent,
supported by small dental plates. Ribbing well marked in the
interior of the valve, but muscular impressions not shown.

Brachial valve nearly flat. Area very narrow; beak small ;
cardinal process simple ; muscular impressions not defined.

Dimensions.—Length=9 to 10 millimetres; width=16 to
17 mm.

Locality and horizon.—The upper section on the Shoot-
Rough Road, Comley ; from the main mass of the Shoot-Rough-Road
Flags, about 4 feet below the Paradoxides-davidis band.

Observations.—Five valves of this species, in the condition of
internal and external casts, have been obtained by Mr. Cobbold.
The British species which it most closely resembles is Orthis hicksir
Salter (Davidson) from the Menevian Beds of St. David’s.' The
Shropshire form is, however, more transverse, the pedicle-valve less
elevated, the cardinal area lower, and the umbonal cavity smaller.
Its dimensions, too, are greater than those given by Davidson for
O. hicksix. The species also approaches a form found in the Para-
doxides-forchhammert Zone of Sweden, which was originally
described by Linnarsson*® as Orthis aff. hicksii and subsequently
designated by Dr. Walcott * Billingsella eaporrecta var. rugosicostata.

The generic position of this fossil is somewhat doubtful, as the
specimens do not exhibit the convex deltidium characteristic of the
genus Billingsella.

1 See T. Davidson, ‘Monogr. Brit. Foss. Brach.’ (Pal. Soc.) vol. iii (1869)
p. 230 & pl. xxxiii, figs. 13-16; and Suppl. zid. vol. v (1882-84) p. 184.

2 Op. jam cit. Bihang K. Svensk. Vetensk.-Akad. Handl. vol. iii (1875-76)
No. 12, p. 13 & pl. iii, figs. 22-23.

3 Proc. U.S. Nat. Mus. No. 1395, vol. xxviii (1905) p. 236.

306 MR. E. 8. COBBOLD ON TRILOBITES [Aug. 1911,

Orruis (Orvsta) cf. LentIcuLaris’ Wahlenberg. (Pl. XXVI,
figs. 24-26.)
Cf. Orthis (Orusia) lenticularis Walcott, Proc. U.S. Nat. Mus. No. 1895,

vol. xxvili (1905) p. 273, where numerous references to Be authors will
be found quoted.

This species occurs as casts in the Shoot-Rough-Road Shales, in a
micaceous shaly sandstone. Owing to the relative coarseness of the
matrix, the surface-characters are poorly preserved, yet sufficiently
to indicate that the ribbing of the shell was rather bold and was
crossed by strong concentric lines of growth. Both valves are
moderately convex, the pedicle-valve slightly more so than the
brachial, the former having an obscure fold (?) and the latter a well-
marked triangular sinus.

The majority of the specimens from the lower section on the
Shoot-Rough Road, Comley, are quite small, about 2 to 23 milli-
metres long by 3 to 34 mm. in width. They are distinctly smaller
than the specimens obtained from the Dolgelly Beds of North
Wales. Further examples, from a rottenstone band in similar
shales in the field north of the same spot, at a horizon perhaps
rather higher than that of the lower section, are larger, ranging up
to 63 millimetres in width.

The imperfect preservation of these shells, as also their small size,
renders their specific correspondence with the Dolgelly form a
matter of uncertainty. Orthis lenticularis is found in North Wales,
Sweden, Norway, and North and South America, and is charac-
teristic of the Peltura Fauna of the Upper Cambrian. The speci-
mens here described may belong to a lower zone.

Ortuis? sp. (Pl. XXVI, figs. 27a & 27 b.)

The only specimen found consists of a fragment of a nearly-flat
valve, covered with numerous rounded costs separated by narrower
rounded interspaces and crossed at intervals by imbricating growth-
lines. Though too incomplete for identification, it differs from all
other known species of British Cambrian brachiopoda.

Locality and horizon.—The upper section on the Shoot-
Rough Road, Comley ; from the main mass of the Shoot-Rough-Road
Flags, in the same bed as Billingsella cobboldi, about 4 feet below
the band yielding Paradowides davidis.

EXPLANATION OF PLATES XXITI-XXVI.
Puate XXIII.
Paradoxides groomit Lapw. (See p. 283.)
[ All the figures are of the natural size. |
Fig. 1. Part of dome of glabella [A, ].

2. Part of glabella showing furrows [A,].

3. Occipital ring [B-].

4, Free cheek [D,]: a, under side; 8, section at the wide end.

5. External cast of the tip of one of the anterior pleurz [A,]: a, concave
view ; 0, sectional view.

|
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Quart. JOURN. GEOL. Soc, VoL. LXVII, PL. XXIII.

Bemnvose Lid., Collo., Derby.

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LAPWORTH, FROM COMLEY.

PARADOXIDES GROOMII,

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BSc Can hele

QuarT. JOURN. GEOL. Soc. VoL. LXVII, PL. XXIV.

7. Bemrose Ltd., Collo., Derby.

PARADOXIDES, etc., FRom COMLEY.

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CAMBRIAN TRILOBITES,

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CAMBRIAN TRILOBITES anno BRACHIOPODS From COMLEY.

Vol. 67.] FROM THE PARADOXIDES BEDS OF COMLEY. 307

Fig. 6. Thoracic segment [1307]: a, seen from above; 3, section transverse
to the thorax.

7. Median pleura [B,,]: @, seen from above; 4, section near the middle
of the length of the pleura; c, cross-section at the fracture.

8. One of the posterior pleure [1308]: @, seen from above; 0, cross-
section at the fracture.

9. Part of pygidium [A,]: a, seen from above ; b, transverse section. The
posterior rounded outline is added from another specimen [A,], the
anterior margins are hypothetical.

10. Hypostoma, cast of interior [B,]. The narrow posterior border is
missing in the specimen, but appears in the external cast [C,], which
also shows the length along the axial line.

[Except figs. 6 and 8, all the specimens are in the Lapworth Collection. ]

Puate XXIV.
[Where no degree of enlargement is stated, the figures are of the
natural size. |
Paradoxides sp. indet. No. 1. Comley Quarry. (See p. 285.)

. Part of glabella and front [1317 a].
. Free cheek [A 476, H. C. B., P,], Mr. Beasley’s Collection.

wee

Paradoxides sp. indet. No. 2. Comley Quarry. “(See p. 285.)

. Part of glabella and fixed cheek [1314].

. Fixed cheek and postero-lateral border [1307 a].

. Part of glabella and fixed cheek [1317 0].

. Pygidium [1171]: a, seen from above; }, from behind ; ¢, from above,
x 3; d, from the side, x 3; e, portion of posterior border much
enlarged.

Paradoxides sp. indet. No. 3. Comley Quarry. (See p. 285.)

Fig. 7. Pygidium, Lapworth Collection: a, seen from above ; 2, from the side ;
c, from behind.

Fig.

SD Ory 09

Conocoryphe emarginata Linnrs., var. longifrons, nov. Comley Quarry.

Fig. 8. Cranidium, seen from above [1317 c¢]. (See p. 286.)

9. Pygidium, probably of this species [A 470, H. C. B., C,]: a, seen from
above; 0, from the side; c, from behind ; all x 3. Drawn from a
plasticine mould of an external cast in Mr. Beasley’s Collection.

10. Free cheek, referred with doubt to this species [13844], x 3.

11. Another specimen, seen from below [1845], Xx 3.

12. Internal cast of cranidium [204]: a, seen from above; 0, from the
side ; c, from behind; all x 3.

13, Internal cast of front and fixed cheek [1341], x 3. This represents
the specimen as viewed from a direction normal to its transverse
curvature, and not from above the complete cranidium. The cheek
appears therefore proportionately wider than in the previous figure.

Paradoxides rugulosus Corda. Shoot-Rough-Road Sandstone, Comley.

Fig. 14. Outline of two very fragile internal casts of cranidia [1180]; the
specimen is now much damaged. (See p. 286.)
15. Glabella and front [1073]: a, seen from above; 0, from the side;
both x 3. ;
16. Pygidium [1082]: a, seen from above; 0, from the side ; c, from behind;
all x 3.

Paradoxides davidis Salt. Shoot-Rough-Road Flags, Comley. (See p. 285.)

Fig. 17. Pygidium [319]: a, seen from above ; 0, from the side.
18. Pygidium, younger form [321]; seen from above.

308

MR, FE. S. COBBOLD ON TRILOBITES | [ Aug. 1911,

Prats XXV.
Dorypyge lakei, sp. nov. Comley Quarry. (See p. 287.)

. Cranidium restored, from specimen [1163] fig.2: @, seen from above ;

b, from the side ; c, from behind; all x 3.

. Two cranidia [1163], natural size.
. A smaller cranidium, with variation in the shape of the glabella

[184], x 3.

. The smallest cranidium found [185]: a, seen from above ; }, from the

side; both x 3.

. Part of a much bigger cranidium [1171] showing surface-markings,

x 3.

. One of the anterior (?) pleurse [1832]: a, seen from above ; 0, sectional

view; both x 3.

. One of the posterior (?) pleura [1337]: a, seen from above ; 4, sectional

view ; both x 3.

. Pygidium [181]: @, seen from above; 0, from the side; c, from

behind ; all xX 3. The spines at the posterior end of the axiai lobe
are restored from another specimen [184].

Agraulos (2) holocephalus Matthew. Shoot-Rough-Road Flags, Comley.

Hig. 9.
10.
ne

Fig. 12.

Cranidium much crushed [562]: @, seen from above ; 6, from the side
both x 2, (See p. 292.)

Smaller cranidium, less crushed [861]: a, seen from above ; /, from the
side; c, from behind; all x 2.

Small cranidium, showing full convexity [360]: a, seen from above :
6, from the side ; c, from behind; all x 2.

Microdiscus sp. Of. M. punctatus Salter. (See p. 292.)

Pygidium : a, one of a group of internal casts [1297], x 3; 0, outline
diagram, X 6; c, the same seen from behind, x 6.

Agraulos sp., cf. Arionellus quadrangularis Whitfield. Shoot-Rough-

Road Flags, Comley. (See p. 292.)

Fig. 13. Cranidium showing convexity [371]: a, seen from above; /, from the

14.
15.

side; c, from behind; all x 2.

Cranidium flattened [370]: a, seen from above; 0, from the side
ce, from behind ; all x 2.

Cranidium, much smaller, with a mere cylindrical glabella and more
strongly marked marginal rim, referred to this species on account
of the form of the cheeks as seen from behind [369]: a, seen from
above; 0, from the side; c, from behind; all x 2.

Agraulos (?) holocephalus Matthew ? Shoot-Rough-Road Flags, Comley.

Fig. 16, Pygidium associated with the two previous species [376]: a, seen from

above; 5, from the side; c, from behind; all x 2. (See p. 292.)

Agnostus fallax Linnarsson. Shoot-Rough-Road Flags, Comley. (See p. 291.)

Fig. 17. Pygidium [346]: a, seen from above; 4, from the side; both x 5.
18. Cephalon [344]: a, seen from above ; }, from the side; both x 5.

Ptychoparia (Liostracus) ? dubia, sp. nov. Shoot-Rough-Road Flags,

Fig. 19.

Comley. (See p. 295.)

Cranidium, exterior [865]: a, seen from above; 0, from the side;
¢, from behind; all x 2.

20. Cranidium, exterior [368]: a, seen from above; 0, from the side;

21.

c, from behind; all x 2.
Cranidium, interior [3866], showing glabellar grooves and ocular ridge,
x 2.

Vol. 67.] FROM THE PARADOXIDES BEDS OF COMLEY. 309

Prate XXVI.

Pitychoparia (Liostracus) pulchella, sp. nov. Shoot-Rough-Road Flags,
Comley. (See p. 293.)

Fig. 1, Cranidium [353]: a, seen from above ; 0, from the side ; c, from beliind ;
all «2;
2. Free cheek [372], referred with reserve to this species; X 2.

Ptychoparia (Liostracus) sp. indet. Shoot-Rough-Reoad Flags, Comley.
Fig. 3. Imperfect cranidium [1113], the only specimen known: a, seen from
above; 0, trom the side; c, section across cheeks and glabella; all
2. (See p. 295.)
Ptychoparia (Liostracus) sp.indet. Hill-House Grits, Comley. (See p. 294.)

Fig. 4. Imperfect cranidium [100]: a, seen from above; 0, from the side ;
c, from behind; all x 2.

Brachiopoda.
Lingulella cf. ferruginea Salter. (See p. 300.)

oF ig. 5. Interior of pedicle-valve, somewhat exfoliated [625], x 4.
6. Pedicle-valve, same individual [624]: @, internal cast ; 0, longitudinal
section; both x 4,

Lingulelia spp. indet. (See p. 301.)

Fig. 7. Partly exfoliated fragment [1033], x 4.
8. a, interior of a brachial valve [710]; , longitudinal section ; both x 4.

Acrothele cf. granulata Linnarsson. (See p. 302.)
Fig. 9. a, fragment of pedicle-valve [682], x 8; 4, surface-granulation, greatly
enlarged.
Acrotreta (Linnarssonia) sagittalis Salter. (See p. 302.)
Fig. 10. Pedicle-valve [705]: a, interior ; }, longitudinal section ; both x 4.

Acrotreta aff. socialis Linnarsson. (See p. 303.)

Fig. 11. Pedicle-valve [1025]: a, exterior ; 0, side view; both x 4.
12. Group of three brachial valves [690], x 4.

Acrotreta aff. socialis Linnarsson? (See p. 303.)

Fig. 13. Pedicle-valve [637]: a, exterior ; J, side view: both x 4.

Billingsella lindstremi Linnarsson, var. salopiensis, noy. (See p. 303.)

Fig. 14. Pedicle-valve [1022]: a, exterior, x 2; 0, surface, X 5; ¢, section of
cost, x 5.
15. Pedicle-valve [1008]: a, internal cast ; b, side view; both x 2.
16. Brachial valve [1028]: exterior, x 2.
17. Brachial valve [1151]: a, internal cast; 2, longitudinal section ;
c, interior from a plasticine mould; all x 2.

Billingsella lindstremi Linnarsson, var. (See p. 304.)
Fig. 18. Pedicle-valve [671]: a, exterior; 0, longitudinal section; both x 2;
c, surface, X 5; d, section of coste, x 5.
19. Brachial valve [665]: @, exterior; 0, transverse section; both x 2.

310 | MR, E. 8. COBBOLD ON TRILOBITES [Aug. IgIt,

Billingsella cobboldi, sp. nov. (See p. 305.)

Fig. 20. Pedicle-valve [1112]: a, external cast; 0, exterior from a plasticine
mould ; ¢c, longitudinal section ; d, section of coste ; all x 2.

21. Pedicle-valve [652]: @, posterior view of internal cast; 0, side view,
restored about the umbo from a plasticine mould of the exterior ;
both x 2. [The specimen has been somewhat damaged since the
figure was drawn. |

22. Brachial valve [654 & 653]: external cast, x 2.

23. Brachial valve, same individual [655]: internal cast, ribs somewhat
damaged, X 2.

All the above brachiopoda are from the Shoot-Rough-Road Flags
and Sandstone, Comley.

Orthis (Orusia) cf. lenticularis Wahlenberg. Shoot-Rough-Road
Shales, Comley. (See p. 306.)
Fig. 24. Brachial valve, internal cast [601], x 4.
25. Pedicle-valve, external cast [614], x 4.
96. Pedicle-valve showing larger dimensions, internal cast [611], x 4.

Orthis? sp. Shoot-Rough-Road Flags, Comley. (See p. 306,)

Fig. 27. a, exterior, from a_plasticine mould of the external cast of a very
slightly convex valve, x 2; 0, section of coste, x 5.

DIscussIon.

Dr. H. Lapworrs, in expressing his sense of the value of the
paper, remarked on the general importance (from the economic
standpoint) of making trench-like excavations, such as those by
means of which the Author had conducted his patient and detailed
investigations.

Mr. T. H. Wrruzrs said that the Author was to be congratulated
on having added a most valuable contribution to our knowledge of
the fauna and succession of the Middle Cambrian beds in the
neighbourhood of Comley. Perhaps the most interesting of the
trilobites obtained by the Author was the form named Dorypyge
lakei, since representatives of the genus Dorypyge were also found
in the Middle Cambrian of North America, Bornholm (Baltic), and
China. ‘Judging from the trilobite fauna described by the Author,
the speaker was of opinion that 1t showed closer affinity to that of
Bornholm than to that of North America, and he would be glad to
know whether the Author concurred in this view.

Miss Ratsrn had been much interested in the paper, all the more
that, owing to the kindness of the Author in sending her instruc-
tions, she had been able to see a little of the sections described,
when she was recently in Shropshire on an expedition with her
students. She would like to ask a question with regard to the
section at Robin’s Tump. It was evident that, in the southern
part, the limestone pebbles would belong to the grit laid down
after the interval of time marked by the unconformity. But what
exactly would be the position and age of the original limestone-
band—the ‘rib of limestone’ in the diagram? It was extremely
interesting to have an example of a limestone in these Cambrian

Vol. 67.] FROM THE PARADOXIDES BEDS OF COMLEY. 311

rocks, the absence of calcareous bands being generally a feature of
these strata in British areas.

Mr. J. F. N. Green thought that the Author’s researches would
throw much light on the succession in the South Welsh Cambrian.
In particular, the unconformity demonstrated in Shropshire might
prove to be of wide extent, as some years ago the speaker had been
led to suspect the existence of a non-sequence in the middle of the
Paradoxidian beds of Pembrokeshire.

The Avrnor briefly thanked the Fellows for their reception of
his paper. He was particularly interested to hear of the signs of
unconformity, mentioned by Mr. Green as occurring at the base

_ of the Menevian in South Wales. In reply to Miss Raisin, he said

that the lower sandstones of Comley were not absolutely barren,
but contained calcareous bands that were fossiliferous. He took
the opportunity of emphasizing the fact that these lower beds had
been deeply eroded prior to the deposition of the Paradoxidian
sediments, the trilobites of which must have inhabited a shore
among pebbles and boulders containing the previously fossilized
Protolenus-Callavia Fauna. The interval might be compared with
that between the Pliocene and the present time. Referring to the
remarks of Mr. Withers, the Author agreed that the Paradowxides
faunas of Comley are closely related to those of Scandinavia; while
the fauna of the Lower Cambrian has stronger affinities with that
of North America.

312 DR. D. WOOLACOTT ON THE STRATIGRAPHY [Aug. IgII,

11. The SrrarigRarny and Tecronics of the Permian of DurHam
(NortHren Area). By Davip Wootacort, D.S8c., F.GS.
(Read April 5th, 1911.)

[ Abstract. ]

Tur Permian strata of Durham and Northumberland lie uncon-
formably on a basin of the Coal Measures. They can be divided as
follows :—

(4) Upper red beds, with salt and thin fossiliferous mag-
nesian limestones (only exposed in the south of Durham).
300 feet.

(8) The Magnesian Limestone.

(a) Upper.
1, Yellow bedded limestone of Roker. 100 feet.
2. The concretionary limestone of Fulwell and Marsden—a series of
concretionary and non-concretionary limestones and marls. 150 to
250 feet.
3. The Flexible Limestone. 10 to 12 feet.

(b) Middle.
Unbedded (asa rule), highly |
fossiliferous (often) lime- | ( Bedded yellow, non-

stone of Claxheugh, Tun- Seal | fossiliferous limestones
pe ee ee meee Sao | of the northern end
of high ground, and reac Se ce of Marsden Bay and
2 aes es 3 300 aes nee | ne ee ee

en brecciated and en- o Seaham Harbour.
tirely changed in character i | Often highly brecciated
—rendered more calcareous | | 150 feet.

and fossils obliterated.
(c) Lower. Bedded brown limestones of Frenchman’s Bay, Houghton
ete. Upper beds often disturbed. 40 to 200 feet.
(2) The Marl Slate. 3 feet.

(1) The Yellow Sands, from 0 to 150 feet.

These beds, which vary much in thickness, lie in North Durham
in the general form of a syncline beneath Sunderland.

The unfossiliferous Yellow Sands are probably a deltaic formation
reassorted by wind, the other beds being the result of deposition in
an inland sea undergoing desiccation. The magnesium carbonate
existed in the waters of the sea, and was either deposited along
with the calcium carbonate, or introduced by seepage when the beds
were being laid down.

Great changes in the amount and distribution of these carbonates
have, however, taken place since deposition. The cellular structures
that occur in the limestone can be classified as follows :—(1) Con-
cretionary-cellular; (2) negative breccia; (3) solution-cavities ;
and (4) fractured cellular. Most of them have been produced by
the leaching-out of the magnesium carbonate (dedolomitization),
or of both that and calcium carbonate. In some cases the rock

Vol. 67.] AND TECTONICS OF THE PERMIAN OF DURHAM. 313

has been rendered crystalline, as well as more calcareous, and the
fossils have been obliterated. They do not afford any proof that
the rock has been dolomitized subsequent to deposition. The per-
centage of calcium carbonate is sometimes over 99, while that of
magnesium carbonate is occasionally as much as 50.

The fauna of the Magnesian Limestone is very restricted (about
140 species) and most peculiarly distributed. The marked
paleontological features are the profusion of individuals in the
Middle Fossiliferous Limestone (which appears to have formed
a snell-bank in the Middle Magnesian-Limestone sea) and their
sudden disappearance in the Upper Limestone. No corals,
echinoderms, polyzoa, brachiopods. or cephalopods have ever
been found above the top of the Middle Fossiliferous division :
only a few fishes, gastropods, lamellibranchs, entomostraca, and
foraminifera occurring in the Upper beds. The Lower and Middle
Fossiliferous Limestones are marked by the presence of Productus
horridus Sow. Fish-remains occur at two horizons: namely, the
Marl Slate and the Flexible Limestone, and the beds above these
deposits.

The Brecciated Beds, which occur at various horizons, chiefly
however in the two Middie divisions, constitute the most marked
tectonic feature of the Magnesian Limestone of the area. They have
been produced by thrusting, which brought about a decrease in the
lateral extension of the Permian. Associated with the breccias
are other proofs of thrusting: (1) Thrust- or shear-planes ; (2) dis-
turbed and displaced masses of Lower Limestone; (3) intruded
breccias; (4) slickensided and grooved, horizontal and vertical
surfaces ; (5) cleavage; (6) folding, both on a local and on a general
scale; (7) buckling, thickening, and squeezing-out of beds; (8) pha-

coidal and other structures; and (9) fissuring. The main thrust.

at Marsden appears to have acted from a few degrees south of east
to a few degrees north of west; there are, however, distinct evi-
dences of movement from other directions in different parts of the
district. Experiments, made on the compressive strength of the
rocks affected by the thrust at Marsden, indicate that the thrusting
reached a maximum of about 300 tons per square foot. Observations
made by Mr. 8. R. Haselhurst, M.Sc., in the Cullercoats area seem
to prove that the thrusting occurred later than the post-Permian
movement of the Ninety-Fathom Dyke—some faulting in the area
is, however, later than the thrusting—, and it appears evident that
the shattering of the strata was produced prior to the pre-Glacial
era of denudation. It may have been connected with the Miocene
movements that produced such marked changes in the physiography
of Britain.

DiscusstIon.

The CHarrman (Dr. C. W. Anprews) suggested that perhaps
comparison of the Permian dolomitic limestones with those of the
post-Miocene raised reefs of Christmas Island (Indian Ocean) might
help to throw some light on the question of dolomitization.

Q. J. GS. Ne. 267 Zz

314 THE STRATIGRAPHY AND TECTONICS [Aug. 1911,

Prof. E. J. Garwoop congratulated the Author on the care and
perseverance of which he had given proof in working out the
Permian geology of an area with which the speaker had been
familiar from his childhocd. He was glad that the Author had
confirmed his own views regarding the original character of the
magnesium carbonate present in these beds. He asked whether the
Author had been able to determine the general direction of the
thrusting over the area to the south of the Tyne Valley, and
whether the movement which produced it could be shown to be con-
nected with the thrust described by Prof. Lebour & Dr. Smythe in °
the Coal Measures farther north; whether any approximate date
could be assigned to these movements ; and whether they belonged to
more than one period. The speaker referred to the difficulties in
explaining the V-shaped breccia-gashes, and asked the Author
whether he accounted for the uninterrupted character of the over-
lying bedding-planes on the view that these had been thrust over the
gashes as a whole; were the nether surfaces of these overlying beds
striated in the manner which the Author had described elsewhere ?
He agreed with the Author that the marly magnesian matrix had
been removed from the beds in which the cellular structure was
developed, but thought that this may often have taken place by
the mechanical action of water. For this reason he deprecated the
use of the term ‘ dedolomitization’ for that process, as the term had
now come into general use for cases where the magnesium was not
removed, but had entered into fresh combinations.

Mr. EK. E. L. Drxon had listened with much interest to the
Author’s discussion of several points of general importance. He
inquired what precisely was the agency that the Author supposed
to have deprived a ‘dedolomitized’ limestone of its magnesium.
Under conditions of ordinary weathering a dolomite is undoubtedly
more resistant than a limestone, unless, as in the case of some of
the dolomites in the Carboniferous Limestone of South Wales,
the dissolution of a slight amount of interstitial calcite releases a
considerable quantity of dolomite in the form of loose erystals or
grains, and enables them to be washed away mechanically. The
disappearance of everything, including insoluble impurities, from
the cavities in the ‘dedolomitized’ lmestones would seem to
demand some such action. Another point raised was the origin
of the dolomite. What was the evidence that any of it was
an original, chemical precipitate ?

The speaker was anxious to hear whether the Author considered
that all the masses of breccia in Marsden Bay had originated in earth-
movements. Prof. Lebour’s explanation—that some of them, the
‘breccia-gashes,’ had been caused by collapse of material into
cavities formed by solution in the liimestone—had led the speaker
to apply the term‘ gash-breceia’ to large masses of breccia, up to
several hundred yards across apparently, in the Carboniferous
Limestone of South Wales. These had undoubtedly originated by
collapse into solution-cavities in the heart of the pre-Triassic
Armorican mountain-chain; and it would be decidedly awkward

— CU

Vol. 67.] OF THE PERMIAN OF NORTH DURHAM. 315

if it were now found that the original ‘ breccia-gashes’” had had an
entirely different origin.

Mr. G. W. Lamexves recalled the overthrust in the Chalk on the
north side of Flamborough Head, which resembled some of the
disturbances described by the Author, and deserved consideration
in discussing the age of earth-movements on the north-east coast.
He further mentioned that a succession comparable to that of
Durham could be traced in the Magnesian Limestone Series of
North-East Derbyshire; but the subdivisions in the two districts
may represent equivalence of phase, without exact equivalence of
time. He enquired whether the Author had observed any dome-like
structures among the more massive limestones of Durham, as such
structures were conspicuous in parts of Hastern Derbyshire and
appeared there to be due to conditions of deposition.

The AvurHor thanked the Fellows present for the manner in
which they had received his paper. He also expressed his thanks
to Mr. 8S. R. Haselhurst, M.Sc., for making the model of the
district shown, and to Mr. C. T. Trechmann, B.Sc., for some of
the specimens of fossils lying on the table. He agreed with
Prof. Garwood’s suggestion that sometimes the magnesium carbonate
may have been removed by the mechanical action of water; but
some of the cellular forms described had certainly been produced
by chemical action. In reply to Mr. Dixon, he stated that, under
certain conditions of temperature and pressure, magnesium carbonate
(in the presence of calcium carbonate) was the most soluble of the
two salts. He emphasized the need for a thorough study of the
relative solubilities of these two carbonates in presence of one
another, and of such other substances as must have existed in the
Permian sea. Both these speakers had referred to the ‘ breccia-
gashes’: he was convinced that the vertical ‘ breccia-fissures’ had
been produced at the end of the period of thrusting; but some of
the triangular ‘breccia-gashes’ may have been caused by the
falling-in of caverns, formed by the mechanical removal of softer
beds or by their solution.

The thrusting in the Permian appeared to be directed towards a
central area; the accentuation of the Coal-Measure basin of North-
umberland and Durham beneath East Durham, as also the synclinal
form of the Permian stratain the same area, was probably produced
by it. That it was connected with some general movement of the
North-of-England strata, as suggested by Prof. Garwood, seemed
certain. The Author regarded it as having taken place between
the Cretaceous and the Miocene Periods.

zZ2

316 MR. HERBERT BOLTON ON j Aug. r9o1t,

12, Fauwat Horizons in the Briston CoatFretp. By Herserr
Botton, F.R.S.E., F.G.S., Curator of the Bristol Natural
History Museum. (Read March 22nd, 1911.)

[Pratt XX VII—Fossizs. |

Tue Bristol Coalfield differs from the Midland and more northerly
fields in the paucity of animal remains which have been discovered
therein. Whereas the last-mentioned coalfields are capable of
division by their faunas alone, the Bristol Coalfield, and the South
Wales Coalfield, can hardly be so treated; and, for the same
reason, no close correlation with the Midland and Northern Coal-
fields can be established, except by means of fossil plants and the
general lithological agreement.

The Bristol Coalfield is largely covered by later rocks, surface-
sections being rare. The search for evidences of a fauna has
therefore to be carried on chiefly under ground, and among
material brought to the surface in the course of mining operations.

By an examination of a measured section at the junction of the
Millstone Grit and Lower Coal-Measures in the South Liberty
Colliery at Bristol, I was able to demonstrate the existence of a
marine fauna in these measures.’ The same method has since been
apphed to the measures underlying the Bedminster Great Vein, and
with successful results. It was shown in my former paper (op. cit.
p. 448) that the Bedminster Great Vein was correlated by Handel
Cossham with the Kingswood Great Vein, so that the measures
examined have a development along the whole of the south-western
side of the Bristol area.

With the guidance of the information obtained from the Ashton
and Bedminster Series, and with the aid of a grant of £20 from
the Royal Society, search has been prosecuted at as many collieries
as possible throughout the Coalfield, and fair results have been
accomplished. Evidence has been obtained of the existence of
fossiliferous horizons at the following collieries :—

South Liberty,
Easton, |
Hanham, \
Speedwell Deep, |
Coalpit Heath, /)
Ludlows, \
Tae le Pit, Radstock,
yning,

Wells Way,
Writhlington, + in Somerset.
Foxcote, |

in Gloucestershire, and near or in Bristol.

Dunkerton,
Newbury,
Mackintosh, J

1 Q.J.G.8. vol. lxiii (1907) pp. 445-69 & pl. xxx.

Wol.67.} FAUNAL HORIZONS IN THE BRISTOL COALFIELD. 317

(1) South Liberty Colliery, Bedminster.

The shaft of this colliery passes through 100 feet of Trias at the
surface, and penetrates the Lower Coal-Measures to a depth of
1386 feet. A generalized section of the shaft is as follows :—

Feet, Feet,

To Bedminster Top Vem .:...........0 630 630
To Bedminster Great Vein ............... 120 750
To: Pond Wenn ete ais co. sc ehiee ads cae 396 1146
To Aghtom Gireatt Vietits. skccicsscesc sce 240 1386

By the courtesy of the Directors of the Ashton Vale Coal & Iron
Company, and of their manager, Mr. A. Fisher, from whom I have
received every assistance, I was able to obtain the services of several
miners, who cut out for me a measured section from the top of the
Ashton Seam upwards to the Bedminster Great Vein.

The material thus obtained was afterwards examined with the
ereatest detail. In all, 760 feet of shale, sandstone, etc. were cut
out and worked over, but the results were disappointing. Four
faunal horizons were determined, the suite of fossils in each being
very small, and the fossils much reduced below the normal size of
the species, except in the case of Anthracomya.

The detailed section cut out was as follows, the beds being
arranged in descending order :—

Examinep Section at Sours Liserty Cotiiery (in descending order).

Thickness in feet inches.

AG. Bed mi Uae ren Wer ce O UN i s.lb. We ckassducecsesadsecesaddaosess

Massive well-bedded bituminous coal.
45. Dark grey fireclay, with small ironstone nodules and abun-

Gait Silesia NOOU GES tee ec siosecsaescsesdacatgndveesencwacs 7 6

44. Mudstone, with a 3-inch band of cannel-like shale ............ 42 9

Lower part crushed.
43. Shale and mudstone. Dark grey, much slickensided and

DEArUN ES PeACES Ob yA eee cs cece cee n cocci tlene'satayedvabiolsent 15
42. Sandstone. Grey, micaceous, and current-bedded ............ 5 3
41. Fireclay. Hard, compact, with ironstone nodules and
Shi SMa EO HOU e Met E Vets ves coi oo <ev'n'ss ssddesabeessasseent. 8 0
£0, Ooal: SOktabee iGeh Mla tee te tenses csc vacvsickescseeseuAbeoecteserts, O 2
39. Grey grit with mudstone, the former showing laminations
of coaly matter, the latter bearing Stigmarian rootlets ... 14 9
38. Fireclay with SECA: oe ie hr 12 0
37. Mudstone, much slickensided and with rootlets ............... 22 1
36. Black shale. ‘ Marine Band,’ ‘ Horizon 4.’ Much slicken-
sided ; yielding obscure plant-remains, also Carbonicola
cf. acuta and Anthr CC OMUUED MICUILUDSE cn tssiesasouee=slnco+- vu sake 3 6
Oss VEC SEOUIGE tars orem eRe ans, (ess. crestcedsenenedeneneeeth 8 0
34. Gritstone. Massive, well-bedded, full of calcite-veins and
[QM USUINSS eee hae sot ence ocodecocee eb tot HOEE BER EEL SEE EEE Eee EERE Cenc e 10 6.
33. Grits and mudstones. Thickness in feet inches.
Dark-grey micaceous grit ..............ss0ee0 0
Micaceous mudstone with plant-remains .... 12 6
Massive amity satewe Pen teens Woks cok se aesies ets | ee
WEG SRG earthy isco oes caeeennceee nse 10 3 30 Li
32. Black and grey shales, wih ede oid twigsand leaves. 22 6

LE 9€ GE

te SSS

S S SS SK
ESS S< SSS SS . SSX SSS SEN : SS as SQESINY 30.0 D>
S> Lp 2%, Le, ly Le Lp 2, =) le >) LEP Le >)
2o 225 “D 25, 2 225, 25 D> 0) pp en, On. 25) Loe oD) 255d “226,
Dn ep 2p po jes Els On > a, Zp,
> ? By 07, ete Ye kp Ay S
Dp 85 Ss ey, Ly 25),
Li
COs &

‘wanonT-ssopy “ri hg = (Cef og, = wnoys nyn.ys fo ssouyoryy, )
"204 WILY MaSMUpo ay) 02 294 WAL UOIYSP 24, WOuLf ‘samMsnapT-[MOQ “aMoT joIsmE oy Jo wWorI0y

Vol. 67.] FAUNAL HORIZONS IN THE BRISTOL COALFIELD. 319
[Section at South Liberty Colliery, cont. | Thickness in feet inches.
ene ckh SCH clic erigimples ee eee EL on dlp emaddeaen cena» 1 10
30. Fireclay. Soft, grey, and much contorted, passing into hard
BARONE LOW Soar oe ee regina isan nas catiaoan «tony = 20 2
29. Quartzose grit, with ironstone. A few traces of plant-
BE TAAUAS “sd, <cocch sche eens <aetett a f02.- sodde sp ode Tencncdeuadies 0
28. Shales and mudstones, with a band of quartzose grit. The }
upper 12 feet much like a fireclay .................. epee ? 30 UV

27. Shale. ‘Marine Band,’ ‘Horizon 3.’ Soft, dark grey,
and well-bedded, containing ironstone nodules. Yields
Anthracomya levis var. scotica, Pterinopecten papyraceus,

Nucula oblonga, Estheria, and Bairdia (2?) ...ssesscseeeeeeee 2 8
me. Camib. - Micaraqun ands meinen oa. sndact oss 52 0~qercene ceceanecaies 2 0
25. Shale. ‘ Marine Band: Horizon2.’ Dark grey, well-bedded,
containing ironstone nodules, Newropteris, Cordaites, etc.,
Anthracomya levis var. scotica, and Naiadites elongata ... 3 fl
24. Shale. Micaceous and massively-bedded ..............eceseeee0 21 0
ae. Coal. “Hartley mid: SWCRGNSIGED: 2025_. 52-2. - acne vee -nerecso-cunses 3 8
22. Fireclay and mudstone: the former slickensided, the latter
yielding obsewre plami-remains: 2.22.2... 05... ..tececseansrscess 26 3
21. Gritstone, with nodular ironstone. Full of Stigmarian root-
Neste arth eng EN oot yah cin enh vind comnie einen ines 32 1
20. Black and grey shales. Micaceous, containing Sphenopteris
and comminuted plant-remains ..................--sseeseeseees 25 +
19. Coal. Bituminous and much slickensided ......... ....... se ae | 0
18. Fireclay, passing into shale below. Stigmarian rootlets
abundant; contains ironstone nodules ................0eeee eee 27 1
17. Shales. Hard grey shale, with ironstone nodules. Contains
AETUTRUET UE NA CITIES) oe sop oom vn sa ann coe son snneacpucsocors 61 4
iG Grey prit. “Wigen alsekeusided 2.5...) ooh)... ce sos ecee cc eneee sone 16 10
15. Shales and mudstones, partly crushed ..............2.sceceeeeeee 44 7
Ee, Grit. ~ Massie atte Weeden 20... 2... i cence cnee or ensecacesetnas ) 4
13. Mudstone. Black and grey, containing ironstone nodules
and many Stigmariam rootlets.............-cecccssssonsceonescens 29 5
t2. Oonl. , Mirekepipome atest toe cise, sos. cp 2c tcsseivgnenesb easier 1 0
1]. Mudstone. Massive grey rock, with Stigmarian rootlets...... 15 10
10. Shale and coal. Mashed-up mass of rock, slickensided every-
where. The shale has all the appearance of a ‘ Marine
‘Bahl amigo eh eee eens oso. ec damn seen ci ocwoneuedeceiaea ts 7 1
9. Mudstone and grit. Massively-bedded and micaceous ...... 15 9
8. Black shale. ‘Marine Band: Horizon 1.’ A soft shale,
easily breaking up, containing Anthracomya levis var.
scotica, Carbonicola sp., and insect-Wings ........seeseeeeee aoe phe
7. Mudstones, with plami-remains «.)....0-2.5..5...006eceesean ss obeee 78 5)
G: Coal, partby equietetyretere sas. odes, . 2. eos opbb an Somebody 4 10
0: Sandstone) amd stele eee wilh eden va euspe naar nee eee ee 22 0
a RL) crassa tagcat ate I asc oe Dison ann aiiahisne 3 0 2 6
3. Sandstone. Massive grey rock, with veins of calcite. Iron-
stone nodules are found in it occasionally ..............2+0e00e 5 )
2. Coal. Soft, and slickensided everywhere .............c0:0ccee0e 7 2
1. Sandstone. Dark-grey, fine-grained rock, with calcite-veins.
TRAE ae ga Ae as slain a soreness Zante ones 16 6
Ashton Great Vein.
Bog tly ss teers x2 759 8

The faunal horizons occur below the Bedminster Great Vein at
depths (below it) of 134, 284, 286, and 637 feet, respectively. Several
of the black shales met with possess the characters of marine-band
shales, but no trace of fossils could be found. At a depth of
326 feet below the Bedminster Great Vein, occurs the Toad Vein ;

320 MR. HERBERT BOLTON ON [Aug 1918

and, while driving operations were being carried on in connexion
with the latter, a small collection of fossils was obtained from the
shales thrown out upon the waste-heap. I have not been able to
localize the horizon.

Attention was also paid to the shales in the vicinity of the
Bedminster Great Vein at the South Liberty Colliery, in the hope
of finding a fossiliferous shale over the roof of this seam.

(2) Easton Colliery.

This colliery lies to the north and east of that of South Liberty,
and has been sunk in Lower Coal-Measures, which here extend
about 700 feet above the Bedminster Great Vein. From the
spoil-heap of the colliery were obtained examples of Carbonicola
aquilina, Anthracomya phillips, Naiadites carinata, and Lingula
mytiloides. The black shale containing the two first-mentioned
species was recognized by Mr. Staple, of aston Colliery, as
forming the roof of the Easton Great Vein, a seam which Godwin-
Austen correlated with the Bedminster Great Vein.

Lingula mytiloides and Naiadites carinata occurred in a thick bed
of black micaceous shale, the first-named species in great numbers.
The shale was indeed a typical ‘ Lingula Shale.’ So far as I have
been able to locate this deposit, it lies somewhere in the vicinity of
what is known as the ‘Five Coals’ Seam, and at about 80 to
100 feet above the Easton Great Vein. The presence of numerous
coprolites was noted, but no trace was found of fish-remains.

(3) Hanham Colliery.

This colliery lies on the eastern outskirts of Bristol, the shaft
passing through a considerable thickness of the Pennant Grit into
the upper portion of the Lower Coal-Measures. From the spoil-
heap was obtained a black shale packed with hundreds of Lingula
mytiloides. A fragment of the dentary of Megalichthys pygmeus
was also found, and a large goniatite which broke up in course of
extraction.

The Lingula Shale of this colliery is identical in all its features
with that from Easton, but I have no information respecting the
horizon at which it occurs. It is quite within the range of proba-
bility that the horizon may be higher in the series. Further
information from this colliery is much wanted.

(4) Speedwell Deep Coltiery, Kingswood.

This colliery lies within the boundaries of the city of Bristol as
now defined, and has been sunk through the Kingswood Series of
Lower Coal-Measures. One of the first seams passed through is
the Doxall Seam, below which come the Lyalong, Old Road, Trough,
Hole or Hard, Five Coals, Thurfer, Great, Giller’s Inn, and Little
Toad Seams.

From the spoil-heap of Speedwell Deep Colliery were obtained
a few examples of Anthracomya minima, A. lanceoluta, and

Vol. 67.] FAUNAL HORIZONS IN THE BRISTOL COALFIELD. 321

Naiadites elongata (?), all in a compact black shale. It is ex-
tremely likely that this shale came from the vicinity of the Little
Toad Seam. Dr. Wheelton Hind has recorded the occurrence at
this colliery of Anthracomya phillips, but the horizon was not
determined.

Upper Coal-Measures of the Northern Portion of the Coalfield.

Examination of the spoil-heaps of collieries in which the Upper
Series are worked has proved that several faunal horizons occur
in the Upper Coal-Measures of the northern portion of the coalfield.

(5) Coalpit-Heath Colliery.

This colliery lies in the northern basin of the coalfield, being
shut off from the larger Bristol portion by the Kingswood Anti-
cline, which brings up the Pennant Grit and Lower Coal-Measures
to the surface. The colliery is about equally distant from Man-
gotsfield on the south, and from Iron Acton on the north. Only
four workable seams are present in the Upper Measures in this
district, the lowest being the High Vein, which is reached at a
depth of 624 feet in the shaft of Coalpit-Heath Colliery. The
lower 152 feet of the shaft gave the following section :—

Feet inches.

PCO VOM oc2.5 25.01 cence 2
: | SPI, aaa a ee 85 0
Bae GWE Moly Bush ceo. goon. 2 6
Ane | SPA) eee Wap eee One Serer 58 0
TELIGT ON ey A ae 5 0

The roof-shales of the High Vein yielded the following series of
fossils :—Anthracomya williamsoni, Naiadites elongata, Leaia leidyi
var. salteriana, Bairdia cf. ampla, Bairdia sp., and Estheria sp.

Lower Coal-Measures of the Vobster Area.

Two collieries opened in the ‘ Vobster and New Rock Series ”
yielded fossils, namely those of Newbury and Mackintosh. The
Mackintosh pit, which is frequently spoken of by the miners as
the ‘ Highbury,’ lies to the south of Radstock, and is deeper than
that of Newbury, two seams of the Vobster Series being worked at
depths of 1242 and 1620 feet respectively. A dark compact shale
from this colliery yielded ostracoda and a fragmentary valve of
Anthracomya (7).

(6) Newbury and Mackintosh Collieries.

The Newbury Colliery lies in the Coleford district, a few miles
south of Radstock. ‘The shaft goes down to a depth of about
720 feet, and near the bottom passes through the upper member
(the Dungy Drift) of the Vobster Series. From the base of the
shaft, a northern branch has been carried below and beyond the

322 MR. HERBERT BOLTON ON | Aug. rg11,

shaft of the Luckington pit, intersecting the following seams of the
New Rock Series :-—

Firestone.
Great Course.
Strap.

Garden Course.
Warkey Course.
Thin Coal.

No. 1 Seam.
No. 2 Seam.
Thin Coal.

The upper part of the Newbury shaft passes through two seams
of the Vobster Series, which normally lie below the Dungy Drift,
but are here uppermost, as all the seams lie reversed. The Dungy
Drift Seam lies at an angle of 45°, dipping southwards, while the
New Rock Series has only a dip of 35° in the same direction.

From the spoil-heap at Newbury Colliery I obtained a dark-
blue shale containing Lengula mytiloides. In determining the
horizon whence this shale came, Mr. J. W. Cottle rendered con-
siderable assistance. Fortunately for purposes of localization, but
one coal, that known as the No. 1 Seam, has been worked for
some time, and therefore it is almost a certainty that the Lingula-
Shale found at the pit-surface came from the roof of this seam.

An incline passes down to the seam from the Luckington shaft,
and some evidence of this Linguliferous horizon ought to be ob-
tained on the spoil-heap of the latter colliery. Mr. Cottle added
that, if these fossils had come from Mackintosh Colliery, which
lies to the west of Newbury Colliery, they would have been derived
from the black shales normally overlying the Coking Coal or Dungy
Drift, but now forming its floor on account of the overturning of
the seams.

From Mackintosh Colliery I obtained, not a Zingula Shale,
but a dark compact shale which yielded ostracods and a frag-
mentary valve of Anthracomya. One small Estheria-like fossil has
a length of 4 millimetres and a depth of 3 mm., and is flatly convex.
It seems a more rounded form than JZ. tenella, but is somewhat
suggestive of that species.

The Radstock Area.

An examination of the spoil-heaps of collieries in the Radstock
area yielded evidences of faunal horizons at several collieries. At
the Radstock collieries it is impossible to trace the shales back to
their source of origin, because the spoil-heap is the common
dumping-ground from several pits. The material obtained from
this common spoil-heap is dealt with in the accompanying pale-
ontological notes under the head of ‘mixed material.’ The spoil-
heap in question is that at Tyning Batch, and material from the
colliery at Wellsway is conveyed underground to Ludlows Colliery,
and thence discharged upon ''yning Batch, which also receives the
material from Ludlows, Middle Pit, and Tyning. This uncertainty

Vol. 67.] FAUNAL HORIZONS IN THE BRISTOL COALFIELD. 323

as to the particular colliery from which material came is regrettable,
because the fossils found are well-marked species and well preserved;
they include forms referable to Anthracomya williamsoni, A. lanceo-
lata, A. minima, and A. phillipsi.

(7) Ludlows and Middle Pits,

These collieries, originally sunk to the Radstock Series, have
since been deepened to the Lower or Farrington Series, and now
pass through the following seams :— .

Great Seam.

Top Little.
First, or Middle.
Radstock Series, Slyving.

Under Little.
( Bull Seam.

( No. 1 or Rock Vein.

No. 2 Vein.
ariel, alae | No. 3 Vein.
Farrington Series eas
* | No, 5 or Smith’s Coal.

No. 6 or Bottom Vein.
| No. 7 Vein, proved, but not yet worked.

A large quantity of shale described by the miners as coming
from the ‘ deep,’ in all probability came from Nos. 1, 5, & 6 Veins
of the Second or Farrington Series. The shale yielded Anthracomya
lanceolata and A. minima.

It is quite within the bounds of possibility that the fossils found
in the ‘mixed’ shales of Tyning Batch came from one or more of
these horizons, although we must not lose sight of the fact that they
might have come partly from Tyning or Wells Way Pits, where the
Radstock Series has been or is now being worked.

(8) Foxcote and Lower Writhlington Collieries.

These collieries are opened up in the Second or Farrington Series
of coals. The highest workable seam is that known as the ‘ Rock’
or ‘ Badger’* Vein, which has been worked at Braysdown Colliery,
Foxcote, Lower Writhlington, and Middle and Ludlows Pits at
Radstock. It is worked at the Greyfield Colliery, Clutton, at the
present time, and also at the first five of the above mentioned
collieries. The ‘ Badger’ or ‘ Rock’ Vein occurs at a depth of
1131 feet in the Lower Writhlington pit, and at 1059 feet in that
of Foxcote. About 300 feet lower down occurs another seam,
known as the ‘Smith’ Seam. From the roof of the Rock or
Badger Vein at Radstock, I was enabled, by the kindness of
Mr. G. E. J. MeMurtrie, to obtain a quantity of shale which on
examination yielded examples of <Anthracomya phillipsi and
A. lanceolata. The specimens of A. phillipsi were few in number,
while A. lanceolata proved fairly abundant.

The shale is of a dark greyish-blue colour, breaks irregularly, and
contains the shells in an uncrushed condition.

324 MR. HERBERT BOLTON ON [Aug. 1911,

The spoil-heap of the Foxcote and Lower Writhlington Collieries
also yielded Anthracomya lanceolata, A. phillipst, A. levis, A.
minima, Naiadites elongata, and Pseudoedmondia sp. nov.

(9) Dunkerton.

The Dunkerton Old and New Pits pass through the First or Rad-
stock Series of coals, which, as we have seen, also occur in the
Ludlows and Middle Pits. In hard micaceous shale from Dunkerton
New Pit I obtained the posterior half of a single fish-scale of
Celacanthus cf. elegans.

Regarding the Upper Division of Radstock as a whole, it may
be said that the Farrington or Lower Series promises to be especially
productive, if it can be worked in regular order and thoroughly ;
but this is a costly and difficult process. Access to the beds can
only be obtained in the mines, and in galleries which usually are
heavily timbered and constantly traversed by loaded wagons.

List oF FOossILs FOUND.

Estheria tenella Jordan. Lingula mytiloides Sowerby.
Estheria sp.

Bairdia ct. ampla? (Reuss).

Bairdia (?)

Leaia leidyi Lea, var. salteriana Jones.

Loxonema sp.
Indet. gen. & sp. (?)

Carbonicola cf. acuta (Sowerby). Gastrioceras listert (Martin).
Carbonicola cf. aquilina (Sowerby). Gastrioceras diadema ? (Beyrich).
Carbonicola sp. Glyphioceras sp.

Anthracomya williamsoni (Brown).
Anthracomya phillipsi (Williamson).
Anthracomya minima (Ludwig).
Anthracomya tanceolata Hind.

Insect-wings.

Anthracomya sp. Strepsodus sauroides (Binney).
Naiadites elongata Hind. Megalichthys pygmeus Traquair.
Naiadites carinata (Sowerby). Calacanthus elegans Newberry.
Naiadites sp. Coprolites.

Pseudoedinondia sp. nov.

Pterinopecten papyraceus (Sowerby). Paleoxyris helieteroides (Morris).

Nucula oblonga (M‘Coy).

Palzontological Notes.

OSTRACODA ann PHYLLOPODA.
HEsTHEria TENELLA Jordan. (Pl. XXVII, figs. 1 & 2.)

This species occurs in the shale bearing Leaia leidyi, var. salteriana
at Coalpit Heath, but in less abundance than that fossil. Isolated
and well-preserved examples are rare, the specimens usually forming
dense clusters, which must have numbered some hundreds of indi-
viduals. ‘The valves in these clusters are crushed and ill-defined,
but in most cases a broadly oval outline can be distinguished, as also
faint traces of concentric striations. Isolated examples are better

Vol. 67.] FAUNAL HORIZONS IN THE BRISTOL COALFIELD. 329

preserved, and show the essential characters of the species. The
best example is that of the left valve with a well-marked and
perfectly straight hinge-line. ‘The umbo is small and crushed, and
does not overlap the hinge-line. The anterior valve-margin is
almost truly semicircular, the ventral margin being broadly rounded,
and passing directly into the more broadly rounded posterior margin
which curves upwards and forwards to the hinge-line. Traces of
numerous fine concentric lines of growth are present on the margin
of the valve, the inner portion being almost smooth, and marked
with what appears to be a faint reticulation. The free margin of
the valve is somewhat inflected along its whole length.

Horizon and locality.—Roof-shales over the High Vein,
Coalpit Heath. stheria cf. tenella (?) occurs at ‘* Horizon 3’
between the Ashton and Bedminster Great Veins, South Liberty
Colliery, Bristol. (See Pl. XXVII, fig. 3.)

EstHERIA sp.

A few examples of a smaller species of Hstheria occur in the
same shale as the last, but are specifically indeterminable.

Horizon and locality.—Roof-shales over the High Vein,
Coalpit Heath; and at 276 feet below the Bedminster Great Vein,
South Liberty Colliery, Bristol.

Barro cf, ampta? (Reuss). (Pl. X XVII, fig. 4.)

Certain elongate oval shells are referred to the genus Bairdva.
They are 6 millimetres long and 3 mm. broad. Lach valve is
flatly convex, broadest in the middle part of the length, and closely
applied along the margin to the opposite valve. No trace of a hinge-
line or of lines of growth can be distinguished. The surface of each
valve is crossed by three vertical, bluntly-rounded ridges which do
not reach the dorsal or ventral margins. In two specimens where
one valve has been crushed into the interior of the other, the
vertical ridges stand out in higher relief.

Horizon and locality.—276 feet below the Bedminster
Great Vein, South Liberty Colliery, Bristol.

Leara Lerpyi Lea, var. saLTERIANA Jones. (Pl. XXVI ie figs. 5 & 6.)

During Mr. D. G. Lillie’s investigations of the fossil flora of
the Bristol Coalfield," he found upon the spoil-heap at Coalpit-
Heath Colliery a small quantity of black shale containing fossils
new to him: these he kindly placed at my disposal. A subse-
quent visit to the colliery resulted in the finding of many more,
and it became clearly evident that a well-defined faunal horizon
existed in the Coal-Measures at this colliery. Examination of the
shale showed that it contained abundant fine examples of the
usually rare phyllopod, Leaa lesdyi var. saltertana, associated

1 ‘Notes on the Fossil Flora of the Bristol Coalfield’ Geol. Mag. dee. 5,
vol. vii (1910) p. 58.

326 MR. HERBERT BOLTON ON [| Auey rewr,

with LEstheria cf. tenella (?), Bairdia cf. ampla (2), Estheria sp ,
Anthracomya williamsoni, and the following plant-remains :—

Cordaites angulosostriatus Annularia ef. stellata (Schloth.).

Grand’Eury. Caulopieris sp.
Cordaites-leaves. Pecopteris sp.
Lepidophylium sp. Pecopteris cf. miltoni (Artis).
Lepidodendron sp. (rimosum | Sphenopteris neuropteris Boulay.
Sternberg ?)

The agent of the Colliery Company, Mr. Hewitt, and the
manager, Mr. Eames, readily assisted in identifying the shale
lying upon the spoil-heap, which they considered came from the
roof of the High Vein. At my request, a quantity of fresh material
was cut out from the roof of this seam and brought to the surface,
when the horizon was at once put beyond doubt, the fresh
material containing hundreds of specimens of Leaza at all stages of
growth. Frequently this fossil occurred in clusters of a score or
more, the clusters being distributed sporadically over the slabs of
shale. The smallest forms are not more than 2 millimetres long,
and all sizes between this and 8 mm. in length are met with.
They are not always parallel to the bedding-plane of the shale,
but disposed at various angles. The stout straight ribs which
stand in high relief upon the surfaces of the valves vary in
number with the size of the fossil, small forms having as few as
twelve lateral ridges and adult forms nineteen.

A cross-section of the valves shows that the dorsal face of each
rib is hollowed, the free edges of the ridges forming sharp knife-
like edges inclining towards the umbo. ‘The lower or ventral
surface of each edge is convex. The radial ridges are sharply
angulated, prominent, and crossed by the concentric ribs, which in
well-preserved valves may impart to the line of the ridges a some-
what crenulated appearance. The hinge-line posterior to the umbo is
slightly excavated in some examples, enclosing a narrow elongated
area, which appears to have remained always open in the form of a
lunule. In front of the umbo, the hinge-line is carried a little
forward, and then merges into a well-rounded anterior border.
All the specimens found agree in general and detailed characters
with Leaia ledyi, var. salteriana, being shorter, deeper, and more
rounded than in the type-species of the genus or of the variety
wrlliamsoni.

The best-preserved forms show a well-marked convexity of the
valves and a fairly prominent incurved umbo. Paired valves are
rarely met with. Where they do occur, they show a markedly
truncated hinder border, which is very characteristic. The regular
curvature of the anterior and ventral borders is one of the chief
distinetions of the variety.

Horizon and locality.—Roof-shales of the High Vein, Park-
field Series, Coalpit-Heath Colliery. |

Vol. 67.] FAUNAL HORIZONS IN THE BRISTOL COALFIELD. 327

PELECYPODA.

CaRBONICOLA AcuTA (Sowerby).

Posterior halves of two shells, showing the lines of growth and
the hinder end of the hinge-line. Both specimens are crushed flat,
and somewhat distorted.

Horizon and locality.—138 feet below the Bedminster Great
Vein, South Liberty Colliery, Bristol.

CARBONICOLA AQUILINA (Sowerby).

One specimen only of this species was found in shale upon the
pit-heap at Easton Colliery. The few other fossils found at this
colliery came from the roof-shales of the Kingswood Great Vein,
and there is reason to believe that this specimen is from the same
horizon.

Horizon and locality.—Roof-shales of the Kingswood Great
Vein, Easton Colliery, Bristol.

CARBONICOLA Sp.

A small crushed shell, not more than 3 millimetres long, too
indeterminate for accurate description. In its produced anterior
border, which bends around the relatively broad umbo and curves
in towards the hinge-line, the specimen, notwithstanding its ex-
tremely small size, is decidedly of a Carbonicola type.

Horizon and locality.—621 feet below the Bedminster Great
Vein, South Liberty Colliery, Bristol.

The absence of Carbonicola, except as one of the rarest of fossils,
is a remarkable feature in the Bristol Coalfield. Had it occurred
here, as in other coalfields, in such profusion as to form ‘ mussel-
bands,’ the fact must have been noted long ago in sinkings.
The place of Carbonicola seems to be taken in some degree by
Anthracomya.

ANTHRACOMYA WILLIAMSONI (Brown).

Examples of this species are rare. The shell is very. thin, and
often absent, leaving a smooth-surfaced internal cast. When
present, the shell is marked by very fine lines of growth, most
evident on the antero-ventral margin. The shale in which the
specimens .are found appears similar to that yielding A. phillipsi,
but the two species have not been seen in association.

Horizon and locality.—Second Series of the Upper Coal-
Measures, Writhlington Colliery, Radstock.

ANTHRACOMYA PHILLIPsr (Williamson).

Several fine examples of this species were obtained from a compact
black shale, which was recognized by miners as occurring near the
Toad Vein at South Liberty Colliery. The outline of the shell
in several instances is perfect, and the wrinkled periostracum is

rs
————————_

ee ee
- = — a
———————

328 MR. HERBERT BOLTON ON [Aug. 1911,

well marked, although the shell itself is as thin as tissue-paper.
Examples of this species were also found in a heavy black bitu-
minous shale with plant-remains, forming ‘ Horizon 4, at about
138 feet below the Bedminster Great Vein at the same colliery.
In the roof-shales of the High Vein, in the Parkfield Series of the
Upper Coal-Measures at Coalpit-Heath Colliery, the remains of this
species are rarely in anything like good condition, although portions
of shell are met with frequently, the part most often preserved
being the posterior ventral margin. In the two best specimens
found, the length along the antero-posterior diagonal is 20 mm.
The small anterior end is not easily distinguished, but the straight
hinge-line and shell-margin are perfectly clear. No evidence of
tumidity is present—the valves lying flat upon the shale, and
showing the somewhat irregular and unequal lines of growth.
The periostracum is usually present and much wrinkled.

Dr. Wheelton Hind records this species from the Lower Coal-
Measures of the Speedwell Pit, Kingswood (Gloucestershire).! The
discovery was made by the late Mr. Stock, but the horizons were
not determined. At Writhlington Colliery in the Radstock district,
Mr. D. M. Watson, of Manchester University, found several fine
examples on the spoil-heap, and others have since been collected
by me. Most of the forms at this colliery have the valvular ridge
much more oblique and pronounced than in specimens figured by
Dr. Wheelton Hind in his monograph, while elongated examples
are not uncommon. In the latter forms, the hinge-line is long and
the posterior ventral border expanded. The umbo in the Writh-
lington specimens is tumid, and in well-preserved examples slightly
overhangs the hinge-line. The shells occur in a soft black shale
with ironstone bands, which splits up very irregularly. The
horizon is not known.

At Foxcote Colliery, the examples of this species are found in
shales of the Second Series of the Upper Coal-Measures, and are
unusually well preserved for so fragile a form. The wrinkles of
the periostracum follow in the main the concentric lines of growth;
but this is not always the case, examples being found in which
the wrinkles are at right angles to the lines of growth, or form
an irregular meshwork. Uncrushed shells are fairly numerous,
and even in those which are erushed the umbones still retain some-
thing of their tumidity. The rock is a dark shale, breaking irregu-
larly, and containing irregular masses of dark-brown material much
similar to coprolitic matter. A few ostracods are scattered through
the shale.

Anthracomya phillipst was also obtained from the roof-shales of
the Easton Great Vein at Easton Colliery. It presents no features
of special interest, occurring sparingly in a compact black shale,
which is well-bedded. The Easton Great Vein of the Lower Coal-
Measures has been correlated with the Kingswood Great Vein.

1 ¢Carbonicola, Anthracomya, & Naiadites’ Pal. Soc. Monograph (1894-96)
joe LAL

Vol. 67.] FAUNAL HORIZONS IN THE BRISTOL COALFIELD. 329

Three examples of A. phillipsi were obtained from a large Upper
Coal-Measure pit-heap at Tyning Batch. In all of them, the shell
was excessively thin, with a much wrinkled periostracum. As
previously mentioned, the spoil-heap at Tyning Batch receives all
the débris from four collieries, namely, Wellsway, Middle, Ludlows,
and T'yning collieries: all working in the Upper Coal-Measures,
but not all in the same series. ‘The difficulty of localizing the
fossiliferous shale is, therefore, insuperable.

Some examples of this ubiquitous species were obtained from
the roof-shales of the Rock or Badger Vein, of the Second or Farring-
ton Series of Radstock. The occurrence of this seam in numerous
collieries in the Radstock district has been elsewhere mentioned.

A few of the examples of A. phillipsi that have been found are
of comparatively large size, somewhat gibbous at the umbo, and
possess a much wrinkled periostracum.

From the foregoing remarks it will be evident that Anthracomya
phillipsi is equally abundant in the Lower Coal-Measures of the
Bristol district and in the Upper Series of Radstock.

Horizons and localities. — Lower Coal-Measures:
Vicinity of the Toad Vein and 138 feet below the Bedminster
Great Vein, South Liberty Colliery ; roof-shales of the Easton Great
Vein, Easton Colliery ; and Speedwell Colliery, Kingswood.

Upper Coal-Measures: Roof of the High Vein, Coalpit-Heath
Colliery ; Writhlington Colliery, Radstock ; Foxcote Colliery, Rad-
stock ; and the waste-heap of Tyning Batch.

ANTHRACOMYA LANCHOLATA Hind. (Pl. X XVII, figs. 7-9.)

This species was founded by Dr. Wheelton Hind * upon a single
specimen obtained at Glebe Colliery, Fenton (Staffordshire), where
a number of seams in the Middle Coal-Measures are worked.
Although Dr. Hind failed to find any other example of this species
in the collections that he examined, there is no doubt that it
is by no means a rare fossil in the Bristol Coalfield. A single
left valve 27 millimetres long was found in massive black shale
at Ludlow Colliery, Radstock, associated with A. minima. Other
examples occur in Lower Coal-Measure shales from the Speedwell
Colliery, Kingswood; and four almost whole and uncrushed
examples were found upon the large spoil-heap of Upper Coal-
Measure shales at Tyning Batch. The latter specimens le in a
fine black shale which splits very irregularly, and shows no evident
lamination or bedding-planes. Finally, from the roof-shales of the
Rock or Badger Vein in the Second or Farrington Series of Rad-
stock, I obtained quite a numerous suite of specimens—several in
yery good condition and uncrushed. One of these was submitted to
Dr. Wheelton Hind, who confirmed my determination of the species.
The numerous examples collected have been subjected to a critical

1 ‘Carbonicola, Anthracomya, & Naiadites’ Pal. Soc. Monogr. (1894-96)
p. 104 & pl. xv, figs. Ll-ll a.
QJ Gis. Nerdzor: 2A

330 MR. HERBERT BOLTON ON [ Aug. 1911,

examination; and I am of opinion that the form ought to be
regarded as a variety of Anthracomya williamsont, and not as a true
species.

Horizons and localities. — Lower Coal-Measures ;
Speedwell Colliery, Kingswood, Bristol; roof-shales over the Rock
or Badger Vein in the Second or Farrington Series, Radstock district.

Upper Coal-Measures: Spoil-heap of Tyning Batch, Radstock.

ANTHRACOMYA MINIMA (Ludwig). (Pl. XXVII, figs. 10-13.)

This species occurs at Radstock; at Speedwell Colliery, Kings-
wood; and at three of the four faunal horizons lying between the
Ashton seams and the Bedminster Great Vein, at South Liberty
Colliery. The shells vary in length from 4 to 8 millimetres, and in
one instance the valves were found united. Specimens found in the
Second Series of the Upper Coal-Measures at Writhlington Colliery,
Radstock, are extremely well preserved in an earthy ironstone, and
show admirably the short hinge-line, the gentle curvature of the
valves, and the broad ovate outline of the shell. Wrinkling of the
periostracum is present, but of a finer character than in A. phillipst,
and it never masks the concentric lines of growth. Upon the
Upper Coal-Measure spoil-heap at Tyning Batch several good
examples were found in a dark shale, very similar in appearance
and character to a dark Upper Coal-Measure shale found at Foxcote
Colliery. The largest specimen obtained had an antero-posterior
length of 18 millimetres and a depth of 7. Good examples of
the species were obtained from a massive black shale in the
Upper Coal-Measures at Ludlows Colliery, where they occurred
in association with A. lanceolata. Two of the attached valves
show the whole length of the hinge-line and the umbones in close
apposition : a lunule also appears to be present. Quite a nume-
rous series was obtained from dark, compact, Upper Coal-Measure
shales at Foxcote Colliery, and all the specimens were in excellent
condition.

Adult individuals of the species form in outline a fairly regular
oval, disposed somewhat obliquely to the hinge-line. The regu-
larity of this oval is but slightly broken dorsally, by the hinder
border of the hinge-line. The latter is straight, extending over
half the length of the shell in very young forms, while in older
examples it may occupy but a third of the length. The umbones
are small, gently rounded, moderately tumid, and lie opposite the
junction of the anterior and middle thirds of the hinge-line.

The posterior ventral border is short, well rounded, and forms
the lowest part of the shell. From the posterior ventral border the
posterior margin passes forwards and upwards, sometimes almost
straight, sometimes with a slight sulcus, until it meets the hinder
end of the hinge-line in a definite and very obtuse angle. In young
forms, the umbones seem almost median to the hinge-line in
position. The surface of the valves is marked by a great number
of concentric lines of growth, much more closely packed than in
Anthracomya phillipsi. They are also clearly independent of

Vol. 67. | FAUNAL HORIZONS IN THE BRISTOL COALFIELD. 331

the thin, much wrinkled periostracum which overlies them, the
wrinkling of the latter diverging in every direction.

Young individuals are much less oblique than older forms, and
have a somewhat rounded quadrangular outline.

A number of beautifully preserved specimens were obtained from
the Upper Series of the Upper Coal-Measures of Radstock. They
serve to show that the roughly quadrangular form which this
species possesses when young is also retained in adult age if the speci-
men be well preserved, and further that the shell is strongly tumid.
A few examples were found in well-bedded Lower Coal-Measure
black shale at Speedwell Colliery. There is no little difficulty in
separating this form from Anthracomya levis var. scotica: the latter
is, on the whole, not so robust a species, and is more broadly
ovate.

Horizons and localities.—At Horizons 1, 2, and 3 below
the Bedminster Great Vein, Lower Coal-Measures, South Liberty
Colliery, Bristol ; in black shale, Lower Coal-Measures, Speedwell
Colliery, Kingswood; in the roof-shales of the Rock or Badger
Vein, Second Series of the Upper Coal-Measures at Writhlington
Colliery, Radstock ; spoil-heap at Tyning Batch, Radstock; in the
Second Series of the Upper Coal-Measures at Foxcote Colliery,
Radstock.

Nazapires eLoneara Hind, (Pl. X XVII, fig. 14.)

A series of uncrushed and well-developed examples of this species
were found at Horizon 2, in the Lower Coal-Measures at South
Liberty Colliery. The resemblance, as they lay in the shale, to
Anthracomya minima was extremely close; but subsequent libera-
tion of one entire specimen showed conclusively that it belonged
to Naiadites. Dr. Wheelton Hind! has already noted this close
superficial resemblance. The shell is markedly tumid in both
valves, transversely elongated, and would be somewhat modioliform
were it not for the well-developed posterior angle of the hinge-line.
Only the faintest trace of lines of growth can be distinguished.
Several of the specimens occur in a compact brown ironstone.
From the roof-shale of the High Vein at Coalpit Heath was
obtained the greater part of aright valve. It occurred in black
shale charged with plant-remains, and in association with Leaia
leidyr var. saltertana. As the valve is uncrushed, the Anthracomya-
like appearance is well shown, and indeed there is nothing
externally evident which would remove this species from that genus.
A finely-preserved left valve from Radstock has come into our
possession. Like all the rest, it is markedly tumid.

Horizons and localities.—Horizon 2 below the Bedminster
Great Vein, Lower Coal-Measures, South Liberty Colliery, Bristol ;
roof-shales of the High Vein at Coalpit-Heath Colliery, Coalpit
Heath ; shales over the Rock or Badger Vein in the Second Series
of the Upper, Coal-Measures, Writhlington Colliery, Radstock.

1 « Carbonicola, Anthracomya, & Naiadites’ Pal. Soc. Monogr, (1894-96)
p. 143.
242

332 MR. HERBERT BOLTON ON [Aug. 1911,

Natraprirss cf. carinata (Sowerby). (Pl. XXVII, fig. 15.)

The cast of a pair of attached valves and two larger crushed
valves were found in a dark shale at Haston Colliery. I consider
them to be examples of this species. ‘The attached valves, though
small, and in the condition of internal casts, are in very good pre-

servation, the anterior adductor muscle-scar impression standing up

in relief upon the left valve. The umbones are small, in apposition,
and angulated. An oblique ridge passes backwards from the umbo
to the posterior ventral border, broadening out towards the latter.

In front of the oblique ridges, the cast shows a shallow fold deepen-

ing anteriorly and ending under the umbones, imparting to the latter
a pinched appearance when viewed from the front. The crushed
valves are 10 millimetres long.

Horizon and locality.

Black Shale, Easton Colliery.

NATtADITEs sp.

The impression of a Naiadites somewhat resembling J. elongata
occurs in well-bedded Lower Coal-Measure black shale, in associ-
ation with Anthracomya williamsoni, from the Speedwell Colliery,
Kingswood, Bristol.

PsEUDOEDMONDIA (?) sp. nov. (Pl. XXVII, fig. 16.)

Considerable interest attaches to this specimen, owing to the rarity
of occurrence of luciniform mollusca in the Carboniferous formations.
Only one specimen was found, in a dark-grey Upper Coal-Measure
shale at Writhlington Colliery, Radstock. It consists of two
attached valves having a length of 8 millimetres, and a depth of
6 mm. in the right valve, which is almost fully exposed. The
umbones are small, incurved, a little anterior to the centre of the
hinge and directed forwards. They are moderately tumid, and
encroach upon, but do not hide, the hinge-line. A small elongated
Iunule les in front of the umbones. The hinge-line is straight, a
little less than the greatest length of the shell, and passes into the
anterior and posterior borders at an obtuse angle. The anterior
border curves forwards and downwards from the hinge-line, and
passes in a well-rounded curve into the ventral border, which is
but slightly convex in outline. The posterior border is regularly
rounded. The general appearance of the valve is that of a broad
oval. The valves are somewhat tumid, the elevation of the umbones
spreading out equally in all directions to the middle of the shell,
from which it gradually dies out in the margin. The ligament
is thin, slightly elevated and rounded, and passes forward, dis-
appearing between the umbones. The surface of the shell is
smooth, but shows under magnification a series of concentric lines
of growth, well spaced out over the middle of the valve, and
crowded together along the anterior and posterior borders.

Horizon and locality.—In massive dark-grey shale, Upper
Coal-Measures, Writhlington Colliery, Radstock.

Vol. 67. | FAUNAL HORIZONS IN THE BRISTOL COALFIELD. 338

PrERINOPECTEN PAPYRACEUS (Sowerby).

A very small fragment of the shell of this species was found in
massive dark shale at Horizon 3, below the Bedminster Great Vein.
The close radiating ribs of this species are so typical, that even
minute fragments can be recognized.

Horizon and locality.—In dark shale, about 279 feet below
the Bedminster Great Vein, Lower Coal-Measures, South Liberty
Colliery, Bristol.

Nocvuza ostonea M‘Coy. (Pl. XXVII, fig. 17.)

Two good examples of this species were obtained at Horizon 3.
The shells measure 7 millimetres in antero-posterior diameter and
4 in depth.

Dr. Wheelton Hind’ describes this species as very rare, and as
only known to occur in the Upper Limestone Shales of Scotland, and
in arenaceous shale at Drumlish (Ireland).

Horizon and locality.—In dark shale, 279 feet below the Bed-
minster Great Vein, Lower Coal-Measures, South Liberty Colliery,
Bristol.

BRACHIOPODA.

LINGULA MYTILOIDEs Sowerby.

In Lower Coal-Measures at the Easton and Hanham Collieries
occurs a fine black shale crowded with hundreds of the shells of
Lingula. Most of the shells are small, but admirably preserved.
On the spoil-heap at Hanham Colliery, where the greater number
were obtained, much of the shale has been fired; but even in burnt
material the shells are distinctly shown. They vary in length from
2 to 6 millimetres, are broadly oval, and have moderately swollen and
often highly polished umbones. At Newbury the species is found
in a dark-blue Lower Coal-Measure shale: the shells are more
uniform than at Easton or Hanham, the length of the valves
varying between 3 and 5 mm., and in all cases the periostracum
ismuch wrinkled. The shales at Easton and Hanham Collieries are
typical ‘ Lingula Shales,’ and very similar to those found at much
lower horizons in the Ashton-Vale Colliery, Bristol.

Horizons and localities.—In the neighbourhood of the
‘ Five Coals’ Seam, Easton Colliery, Bristol; ? Roof of No. 1 Seam,
Newbury Colliery, Coleford, near Radstock.

GASTEROPODA.

A few gasteropods were found in Lower Coal-Measure shales
thrown out upon the spoil-heap at South Liberty Colliery ; but, with
one exception, all were minute and too destitute of determinable
characters to be described.

* ‘Monogr. Brit. Carb. Lamellibr.’ Pal. Soc. vol. i (1896-1900) p. 188.

334 MR. HERBERT BOLTON ON (Aug. Ig1I,

LoxonEMA Sp.

The single exception above-mentioned is an acutely turreted
shell 5 to 7 millimetres in height, and consisting of six whorls. In
general character it agrees with Lowonema ashtonense, obtained by
me from an adjacent colliery and described in this Journal." The
surface of the shell is smooth, and lacks the longitudinal striz seen
in Z.ashtonense. I regardit as a species allied to the latter, but the
specimen is not sufficiently good to serve as the type of a new species.

Horizon and locality.—Shales in the neighbourhood of the
Toad Vein, Lower Coal-Measures, South Liberty Colliery, Bristol.

CEPHALOPODA.

A small collection of goniatites was obtained, along with the
gasteropods, upon the spoil-heap of South Liberty Colliery. A small
series of minute coiled shells found in the shales may possibly
be the try of goniatites, or of gasteropods, or of both.

GaAsTRIOCERAS LISTERI (Martin).

A portion of the outer whor! of a large shell of this species was
found.

Horizon and locality.—Shales in the neighbourhood of the —
Toad Vein, Lower Coal-Measures, South Liberty Colliery, Bristol.

GLYPHIOCERAS DIADEMA ? (Beyrich).

A very small pyritized fragment of the inner whorls of a goniatite
fortunately showed traces of the suture-lines, and I am indebted to
my friend Mr. G. C. Crick for his views of its relationship.

Horizon and locality.—Shales in the neighbourhood of the
Toad Vein, Lower Coal-Measures, South Liberty Colliery, Bristol.

Evidence of the occurrence of large goniatites has been obtained
in ironstone nodules, found upon the spoil-heap in Lower Coal-
Measures at Hanham Colliery. The material is very refractory,
and in no case could a specimen be got out, or uncovered in such a
way as to secure a clue to its genus and species.

INSECTA.

GENENTOMUM SUBACUTUM, sp. nov. (PI. XXVII, figs. 18 & 19.)

Two small wing-fragments, 9 millimetres in length and 6 mm. in
breadth. One wing is partly superposed upon the other, the
lower one having its surface also in part concealed by matrix. The
uppermost wing is represented by a fragment of the distal hinder
portion, and by the wing-apex, which is bluntly rounded. The whole
aspect of the wing-fragment is pyriform; but this is doubtless
misleading, as the outer margin is broken away, and no true
approximation to the original size or shape can be obtained. The

1 “On a Marine Fauna in the Basement-Beds of the Bristol Coalfield’
vol. lxiii (1907) p. 464 & pl. xxx, figs. 17 a-17c.

Vol. 67.] FAUNAL HORIZONS IN THH BRISTOL COALFIELD. 330

surface is crossed by one vein forking three times, and by five other
veins, two of which bifurcate twice. All the veins are narrow and
deep, while the interspaces are crossed at right angles by trans-
verse veins which divide them into somewhat regular rectangular
areas. Where forking of the veins takes place, the resultant
branches first diverge rapidly, and then pass outwards at right
angles to the wing-margin in parallel lines. The upper and lower
branches of the third and fourth veins appear to run together, and
must ultimately fork a little beyond the present broken edge. The
hinder edge is somewhat sinuated. There can be no doubt, how-
ever, that the margin is broken away, and stiil hidden under the
matrix of the counterpart block of shale.

Notwithstanding the fragmentary character of the wing, it is,
I believe, possible to determine that the veins described are
portions of the radius, the trifurcate upper vein forming the apex
of the radius, and extending somewhat forward of the tip of
the wing. A little of the distal outer margin can be traced in
front of the tip of the wing. The small area enclosed between it
and what I suppose to be the main axis of the radius (that is,
the trifurcate vein) is crossed by fine, short, deeply-incised veins.
The lower wing-fragment has a well-defined outer (?) margin
evidently bounded by the costal vein. It is regularly and broadly
convex, and shows signs of passing into a straight or incurved line
proximally. The tip of the wing is narrow and bluntly rounded.
Five longitudinal veins are present, the third forking just in front
of the fractured proximal edge. The fifth vein forks about 2°5
millimetres below the tip of the wing. All the veins run out into
the costal margin.

These wings, fragmentary though they be, present features of
unusual interest, as they are wholly unlike blattoid wings in every
particular ; and their relationship must be sought for in other groups.
The resemblance in venation and in structure to fragments of
locustid wings is remarkably close. There are the small, thin,
sharp longitudinal veins in each; the division of the interspaces by
transverse branches into rectangular areas; and the fragments show
a texture which was quite filmy, apart from the marks left by the
veins: this again is a locustid feature.

Wings of ahaa character were classed by Shikiter in a genus
Guanes referred by him to the family Homothelide. Brauer
found an affinity in Scudder’s form to the Sialids, while Bron-
gniart recognized its relationship to the Orthopteres sensw stricto.’
Dr. Handlirsch refers Scudder’s genus to a new family Midischiide,
in which the forms are characterized by the coalescence of the
superior branch of the median vein of the front wing with the
radial sector, and its bifurcation farther out as an apparent offshoot
of the latter vein.

So far as determination of such fragments is possible, I should
assign the above-described specimens to Scudder’s genus Genentomum

1 A. Handlirsch, ‘ Revision of American Palzozoic Insects’ Proc. U.S. Nat.

Mus. vol. xxix (1906) pp. 661-820, especially pp. 700-701.

336 MR. HERBERT BOLTON ON [Aug. 1911,

with its distinct locustid affinities. It is interesting to note that
Dr. Handlirsch has observed that in one of the forms of this
group the hind legs were developed for jumping, precisely as in
locustids.

Horizon and locality. — 637 feet below the Bedminster
Great Vein and 137 feet above the Ashton Great Vein, Lower
Coal-Measures, South Liberty Colliery, Bristol.

PISCES.
Cartacantuts cf. rLEGANS Newberry.

Horizon and locality.—Micaceous shale of the Upper Series,
Upper Coal-Measures, Dunkerton Colliery. |

SrREPsODUS SAUROIDES (Binney).

Impression of a scale, in dark-blue shale seamed by brown earthy
ironstone-bands.

Horizon and locality.—Dark-blue shale near the Rock or
Badger Vein, Second Series of the Upper Coal-Measures, Writhlington
Colliery, Radstock.

MecALIcHTHYs Pyemzus Traquair.

Fragment of dentary in Lower Coal-Measure Lingula Shale.
Hanham Colliery.

Coprolites. —

Several small coprolites occur in the Anthracomya - phillipsi
Shale at Easton Colliery.

INCERTA SEDIS.
PAaL#OXYRIS HELICTEROIDES (Morris). (Pl. X XVII, figs. 20 & 21.)

One example of this still problematic form was found at a depth
of 279 feet below the Bedminster Great Vein. It presents the
usual fusiform body, and is broken off a little above the point at
which it is joined by the pedicle. The beak is almost intact,
but the segments, instead of running parallel and longitudinally
to the apex as described by Dr. Moysey,’ continue the spiral
twists seen upon the body. The specimen is either more attenuated
than usual, or partly concealed along the sides. The total length
is 25 millimetres and the maximum breadth 4 mm., the beak being
about 12mm. long. The alternation of broad and narrow bands
characteristic of P. helicteroides is clearly marked, and is continued
upon the beak, where the bands lose most but not all of their spiral
character.

The whole question of Palwoxyris and its affinities has been so
recently considered by Dr. Moysey (op. cit.) that nothing need be
added here, beyond the record of its presence in the Lower Coal-
Measures of the Bristol Coalfield

1 «On Palgoxyris & other allied Fossils from the Derbyshire & Nottingham
shire Coalfield’ Q. J. G. S. vol. lxvi (1910) p. 331.

Vol. 67.]

SYNOPSIS OF THE FAUNA
OF THE

Bristot Coat-MEASURES.

Echinodermata.

Crinoidal columnals

Vermes.

Mionmnamana see
Spirorbis pusillus (Martin) .

Brachiopoda.

Lingula mytiloides Sowerby _.........
Orbiculoidea nitida (Phillips) ..

Orthotetes cf. crenistria (Phillips) . ok

? Derbya senilis (Phillips)

Chonetes cf. hardrensis Phillips Be ei:

Chonetes sp. .
Productus cf. antiquatus Sowerby ..
Productus concinnus Sowerby ..

Amboceelia aff. urii (Fleming) ....... “

Pelecypoda.

Carbonicola cf. acuta (Sowerby) ..
Carbonicola cf. aquilina (Sowerby)
Carbonicola sp. .... siseeo
Nucula equalis Sowerby ..

Nucula oblonga M‘Coy ..

Nuculana acuta (Sowerby) . —

‘Parallelodon tenuistriatus (M‘Coy)
Tellinomorpha (?) hindii Bolton

Posidoniella kirkmani (Brown) .......:.

Posidoniella levis (Brown) .....
Posidoniella minor (Brown).....
Schizodus antiquus Hind ...
Aviculopecten gentilis Sowerby
Pterinopecten carbonarius Hind..
Pterinopecten papyraceus (Sowerby) ..
Paleolima retifera Hind (MS.) .
Pseudoedmondia, sp. nov.? .........-
*Modiola, sp. nov.? ... =e
Anthracomya lanceolata Hind —
Anthracomya minima (Ludwig) ..
Anthracomya phillipsi (Williamson)...
Anthracomya williamsoni ae
‘Naiadites elongata Hind .....
‘Naiadites cf. carinata (Sowerby)...
Naiadites sp. Since te seeeent

See eer eee

eet weer

FAUNAL HORIZONS IN THE BRISTOL COALFIELD.

337

LowER

C

OAL-

MEASURES.

Vobster, Ashton &
Bedminster Series

xxXxX KKK KK XK x X

XXX XX

XXKXKKXKKKE KKKKKKKXKKXKXK

i

New Rock Series.

| Pennant Grit.

ES

cond or Farrington
Series.
| Red Ground.

| Fi

su PR OG Oe OOK:

UPPER
CoaAL-
MEASURES.

ae ET TN

rst or Upper Rad-

stock Series.

ao |

SYNOPSIS OF THE FAUNA

OF THE
Bristot Coat-MEASURES

(continued).

Gasteropoda.

Raphistoma acutum Bolton ............ 06. .0006.
Raphistoma radians (de Kon.)..................
Pleurotomaria carinata (Sowerby) .. |
Pleurotomaria SSN I (Phillips) .. Shen
Euphemus urii (Fleming) .. eae sta ete
Bellerophon bicarenus Lév. ssditalieis

Bellerophon hiulcus Martin, vpeewre Me

Flemingia sp. ... Sata
Macrocheilus cf. ventricosus de Kon. ........
Loxonema ashtonense Bolton eee
Loxonema scalaroideum Phillips .............
Loxonema sp. .... BA ai ta tiselatess eesti
Naticopsis disjuncta Bolton :

Cephalopoda.

Orthoceras cf. conquestum (de Kon.) .........
Orthoceras cf. cylindraceum Fleming ......
Pleuronautilus costatus Hind ................
Nautiloid shell é

Temnocheilus cf. tuberculatus Sowerby _
Glyphioceras coronatum Foord & Crick
Glyphioceras diadema ? (Beyrich) ........
Gastrioceras listeri (Martin) . ae

Arthropoda.

Leaia leidyi var. salteriana Jones ........
Estheria tenella Jordan

Vobster, Ashton &
Bedminster Series

KKK KK KK KK KK KK

x KK KKK KK

E'stheria sp. .

Bairdia cf ampla (Reuss)

Bairdia sp. Lona
Genentomum subacutum sp. ‘nov.

Pisces.

Diplodus gibbosus (Binney) .. Renee
Pleuroplax rankinei (Hane. & Att.) Lee a
Megalichthys pygmeus Traquair 5005
Strepsodus sauroides (Binney) oe
Colacanthus elegans Newberry ..............
Rhadinichthys monensis Gee
EHlonichthys sp. tick ea aae
Acrolepis sp.

Coprolites ...

Paleoxyris helicteroides (Morris) ...........

OX:

: (KX

KOS OG:

LowER
CoAL-
MEASURES.

Sa aN

| New Rock Series.

| Pennant Grit.

[he

?

cond or Farrington

j Series.
| Red Ground.

UPPER
CoAL-
MEASURES.

|

rst or Upper Rad-

stock Series.

i

XX XK X

Vol. 67.] F\UNAL HORIZONS IN THE BRISTOL COALFIELD. 339

Range of Species.

The accompanying synopsis (pp. 337-38) comprises the fossil
forms from the Bristol Coalfield that have been determined by the
writer during recent years. It shows that the Ashton and Bedminster
Series of Bristol, the Coalpit-Heath and Parkfield Series of the
northern part of the Coalfield, and the Vobster Series of Radstock
which form the basement series of the Lower Coal-Measures, are
all characterized by a fauna agreeing with the typical fauna of
the Lower Coal-Measures in the coalfields of the Midlands and
of Lancashire and Yorkshire.

There is, however, a dearth of species of Carbonicola, while the
fauna is poor in cephalopods and fishes. Gasteropods are, however,
almost as abundant in species as in other coalfields.

No forms are known from the New Rock Series of the Lower
Coal-Measures; but this is probably due rather to lack of opportunity
for examining adequately the measures, than to an actual paucity
of fossils. The Second or Farrington Series of the Upper Coal-
Measures has yielded one brachiopod (Lingula mytiloides), several
species of ostracods, four species of Anthracomya, and one fish
(Strepsodus sauroides). All the species of Anthracomya found in
the Farrington Series, as well as Strepsodus sauroides, also occur
in the Lower Coal-Measures.

Celacanthus elegans occurs in the First or Upper Radstock Series.
Both Strepsodus sauroides and Celacanthus elegans are typical Lower
Coal-Measure forms, which in the Bristol Coalfield pass up much
higher in the Coal-Measures than they do elsewhere.

The tabulation of species establishes, moreover, the fact that
marine horizons are not restricted to the Lower Measures, but also
occur in the Upper Coal-Measures.

Similar evidence of the upward range of marine phases in the
Coal-Measures has been recently obtained in the Yorkshire Coal-
field at Maltby, where Mr. W. H. Dyson* found an extensive
fauna in four horizons, the lowest being 340 feet above the
Barnsley Coal, and the highest occurring 1000 feet below the
summit of the Middle Coal-Measures. This marine fauna is essen-
tially of the type formerly regarded as restricted to the Lower Coal-
Measures, if we except the well-known marine band in the Middle
Coal-Measures found by the late Prof. A. H. Green at Dukinfield. It
also shows some relation to the marine fauna of the Bristol Coal-
field. This is demonstrated by the presence of Lowonema ashtonense
in a marine band lying about 709 feet above the Barnsley Coal.
This fossil was first described by me from the Ashton - Vale
Colliery, Bristol, where it occurs low down in the Lower Coal-
Measures. Other forms common to the Bristol and Yorkshire
higher measures are Lingula mytiloides and Calacanthus. The
discoveries in the Yorkshire Coalfield emphasize the fact, much

1 <The Occurrence of Marine Bands at Maltby’ Geol. Mag. dee. 5, vol. vii
(1910) p. 520.

340 MR. HERBERT BOLTON ON [ Aug. rgrt,

more than the forms now recorded from the Bristol Coalfield, that
marine phases are not restricted to the Lower Series, but pass
upwards to near the top of the Middle Coal-Measures in Yorkshire
and into the Farrington Series of the Upper Coal-Measures in the
Bristol and Somerset area.

Further, it is evident that the marine fauna undergoes no marked ~
change throughout—forms common in the Lower Coal-Measures
ranging upwards, and not being replaced by new species. This lack
of mutability will probably prevent the use of marine bands for
zonal purposes. The continuity of life-forms in the Middle Coal-
Measures of Yorkshire is strikingly complete, less so in the Bristol
Measures; but even here the long interval represented by the
deposition of over 1000 feet of Pennant Grit has not sufficed to
prevent their recurrence at higher levels.

The presence of fragments of insect-wings in the Lower Coal-
Measures at South Liberty Colliery, Bristol, is of interest and
suggestive, since. insect-wings are also known in the South Wales
Coalfield,’ which must originally have been joined up to the Bristol
Coalfield. |

It may not be inopportune to put on record my conviction that
the three Coal-Measure genera, Carbonicola, Naiadites, and Anthra-
comya, will yet prove to be characterized by only a few definitely
marked forms worthy of specific rank, and that around each of such
species it will be possible to group a number of variants, some of
which are now regarded as valid species. It is quite possible to
select two or more types, and between such selected forms to place
a graduated series which effectually bridges the interval, so that
one selected species seems to pass by a series of stages into another.
This is easily done with several of the present species of Carbonicola,
which can be thus joined zp with C. aquilina and C. acuta.

The power of variation or mutability (in De Vries’s sense)
possessed by these genera would seem to have been very great, or
their response to the conditions of environment very ready. I am
also inclined to the belief that dissimilar and relatively fixed species
occurring at widely separated horizons have produced under the
stimulus of environment, or of some other cause, a series of variants
or mutations precisely similar in outward form and character.

EXPLANATION OF PLATE XXVII.

Fig. 1. Estheria tenella Jordan. Magnified 3 diameters. Roof-shales oyer
the High Vein, Coalpit-Heath Colliery. (See p. 324.)

2. Hstheria tenella Jordan. Portion of a clustered mass showing the
general mode of occurrence. Natural size. Same horizon and
locality as fig. 1.

3. Hstheria ef. tenella Jordan. In shale between the Ashton and
Bedminster Great Veins, South Liberty Colliery, Bristol. A smaller
and more oval form than the Coalpit- Heath type, magnified
3 diameters. (See p. 325.)

' Q. J. G. S. vol. Ixvii (1911) pp. 149-74 & pls. vii-x.

1
Bemrose Lid., Collo., Derby.

QUART. JOURN. GEOL. Soc, Voc. LXVIJ, PL. XXVII.

Photo.

J. W. Tutcher,

Fi ars BR I RD TERT " = F =

MARINE FOSSILS FROM THE BRISTOL COAL-MEASURES.

Vol. 67.] FAUNAL HORIZONS IN THE BRISTOL COALFIELD, 341

Fig. 4. Bairdia cf. ampla (Reuss). Magnified 3 diameters. In shale 276 feet
below the Bedminster Great Vein, South Liberty Colliery, Bristol.
(See p. 325.)

. Leaia leidyi, var. salteriana Jones. Roof-shales over the High Vein,
Parkfield Series, Coalpit-Heath Colliery. Paired valves. Magnified
3 diameters. (See p. 329.)

6. Leaia leidyi, var. salteriana Jones. Portion of a clustered mass,
showing the general mode of occurrence. Natural size.

. Anthracomya lanceolata Hind. Uncrushed valve from the roof of the
Badger Vein, Second or Farrington Series, Radstock. Magnified
15 diameters. (See p. 329.)

. Anthracomya lanceolata Hind. Conjoined valves. Natural size.
Radstock.

9. Anthracomya lanceolata Hind. Right valve somewhat flattened.
Natural size. Ludlows Colliery, Radstock.

10. Anthracomya minima (Ludwig). Young shell with short hinge-line.
Magnified 2 diameters. Upper Coal-Measures, Foxcote Colliery,
Radstock. (See p. 330.)

11. Anthracomya minima (Ludwig). Adult shell showing increased deve-
lopment of hinge-line, marked obliquity of valve, and much wrinkled
periostracum crossed by lines of growth. Magnified 2 diameters.
Upper Coal-Measures. Foxcote Colliery, Radstock.

12. Anthracomya minima (Ludwig). Short, somewhat quadrangular form
with small well-developed umbo. Magnified 3 diameters. Foxcote
Colliery, Radstock.

13. Anthracomya minima (Ludwig). Attached valves showing the straight
hinge-line, and small pointed umbones which are almost in apposition.
Magnified 2 diameters. Ludlows Colliery, Radstock.

14. Naiadites elongata (Hind). Natural size. Shales over Rock or Badger
Vein, Second Series of the Upper Coal-Measures, Writhlington
Colliery. (See p. 331.)

15. Naiadites cf. carinata (Sow.). Natural size. Black shale, Easton
Colliery. (See p. 332.)

16. Pseudoedmondia (?) sp.nov. Attached valves. Magnified 2 diameters.
Upper Coal-Measures, Writhlington Colliery, Radstock. (See

. 332.)

1: Nicila oblonga (M‘Coy). Magnified 3 diameters. In shale, 279 feet
below the Bedminster Great Vein, Lower Coal-Measures, South
Liberty Colliery, Bristol. (See p. 333.) ;

Figs. 18 & 19. Genentonum subacutum, sp. nov. Magnified 2°5 diameters. In
shale, 637 feet below the Bedminster Great Vein, Lower Coal-
Measures, South Liberty Colliery, Bristol. (See p. 334.)

20 & 21. Paleoxyris helicteroides (Morris). Magnified 2 diameters.
Showing the spiral arrangement of the segments continued upon
the beak. (See p. 336.) In shale, 279 feet below the Bedminster
Great Vein, Lower Coal-Measures, South Liberty Colliery, Bristol.

or

OO

342 THE AVONIAN OF BURRINGTON COMBE. [Aug. IgIt,

13. Faunat and Liruotogicat Sequence in the CARBONIFEROUS
Limestone Series (AvonrAn) of BurRINGTOoN ComBE (SOMERSET).
By Prof. Stpnsry Huew Reynorps, M.A., F.G:S., and Arraur
Vaueuan, M.A., D.Sc., F.G.S. (Read May 10th, 1911.)

[Puares XX VIII-XXXT_]

ConrTEnts.
Page
i dntroduction’ Uh s Se bo oe 342
II. Description of the Important Rock-Types, arranged Zonally
and Lithologicalliy, (a(S: Mek 8p) iene. .2scetcaeeesteen eee ee eee 344
III. Faunal Lists and Notes on the Zonal Faunas. (A. V.)......... 362
EV. Baleontolopy.:)eCAnWe etic ccc sssateke. scxwectee s-seereeeene Bry o71

V. (a) Physiographical Comparison of the Burrington Sequence
with that at other points of the South-Western and

Beleian Provinces: (Aj Vi) pee. seid) aicetilins me <pee se eee eee 38d
(6) Comparison of the Upper Paleozoic Corals with the Lower
Palxozoic Graptolites, in regard to Occurrence, Distribu-

tion, and Myolutiom, (A. V2). -.:k.es.ce. 5-5 ee eee 389

I. IntrRopvctrion,

Tue magnificent section of Burrington Combe, first studied by
Prof. C. Lloyd Morgan,’ was described in considerable detail in
1905 by Mr. (now Dr.) T. F. Sibly.* This author laid down, as
accurately as was possible at the time of his publication, the broad
zonal sequence of the faunas. The very large amount of research
that, during the last six years, has been devoted to the Carboni-
ferous Limestone Series, both in the British Isles and in Belgium,
has demonstrated the importance of more detailed lithological
investigations and the possibility of tracing the evolution and migra-
tion of the great Carboniferous gentes of Corals and Brachiopods.

The field-work has extended over several years, and we owe
much to the willing assistance of many Bristol geologists, especially
to Mr. W. H. Wickes and Mr. H. F. Barke.

The series of views (figs. 3-10, pp. 354-61) illustrate the whole
sequence, and are labelled with zonal and faunal indices; the
precise points at which important rock- “types occur are also marked
upon them by means of numerals.

1 “Mendip Notes’ Proc. Bristol Nat. Soc. n. s. vol. vi (1889- 91) p. 169.

2 «The Carboniferous Limestone of Burrington Combe’ Proc. Bristol Nat.
Soe. ser. 4, vol. i (1904-1907) p. 14; see also A. Vaughan, ‘ Paleeontological
Sequence in the Carboniferous Limestone of the Bristol Area’ Q. J.1Giis
vol, xi (1905) pp. 248-50.

Fig. 1.—Map of Burrington Combe and the immediate
neighbourhood.

220 yas. “AMile if
i Burringlon

fv

‘87
we Burringlon.
Cheerely

\\

B
~
A
8

344 PROF. 8. H. REYNOLDS AND DR. A. VAUGHAN ON [Aug. Iort,

II. Description oF ton Important Rocx-TyPEs, ARRANGED
ZonALLy AND Litnonoeicatty. (S. H. RB.)

[The traverse is from north to south, the zones being thus
encountered in descending order. |

VISEAN.
Lowrr Dizunorpuyri_Lum Zone (D,).

Extent.—The top of Quarry 1 and the hillside on the north.
Thickness.—A thickness of about 20 feet is exposed in the -
quarry, and perhaps 80 feet beyond it.

The D beds exposed consist entirely of fine-grained and crys-
talline grey limestone. The red coloration, which is as a rule so
characteristic of the D beds of the Bristol district, is not seen at
Burrington. ‘The rocks exposed in the quarry are uniformly and
somewhat strongly crinoidal. In some bands Dibunophyllum is
sufficiently abundant to form an appreciable part of the rock,
Sections show that the limestone exposed on the hillside is full of
foraminifera, and much like that forming the bulk of the S and C,
beds.

Urrer Seminuca Zone (os):

Extent.—From nearly the top of Quarry 1 to nearly the top of
Quarry 2.
Thickness.—540 feet.

The 8, beds may be subdivided as follows, in descending order :—

S, (d). Thinly-bedded, very variable series, consisting in the main
of compact horny limestone (china- stone) often concretionary and
showing imperfect *‘ Cotham-Marble’ structure, alternating with
limestone often oolitic containing Seminula bands, and including a
more shaly development in the upper part. This horizon is the
representative of the ‘concretionary beds’ of the Avon, Sodbury,
and other sections in the neighbourhood of Bristol, and is exposed
in Quarry 1.

S, (c). Fine-grained, generally foraminiferal grey limestone, with
Seminula bands. Exposed on the hillside.

S,(6). Fine-grained grey limestone, containing many strong bands
of Lithostrotion martina and much chert. Exposed on the hillside.

S, (a). Grey limestone, commonly oolitic ; the upper beds are very
poorly exposed on the el sla. the lower are well seen in Quarry 2.
A little dolomitization has occurred at one level in the upper beds.

Further Account of the Lithology of the S, Beds.

Many of the lithological types occurring in the Burrington section
are identical with those of the Avon section, and have been already

Vol. 67. ] THE AVONIAN OF BURRINGTON COMBE. 345

described by one of us.’ The ‘china-stones’ of the Burrington
section agree with those of the Avon section in their extremely
compact horny texture and conchoidal fracture, but are not so
black on a freshly-broken surface, and do not weather so white as
do those from §, in the Avon section.

The ‘ concretionary beds,’ which are best seen at about the middle
of the quarry, are essentially the same as those of the Avon section,
and the account given in the paper already referred to of the
peculiar ‘ Landscape’ or ‘ Cotham-Marble’ structure is applicable to
the Burrington rocks. Sections (see Pl. XXVIII, fig. 1) show that
this type of rock is to a large extent made up of a mass of small
interlacing tubules, which Dr. Bather suggests may be calcareous
alge. Dr. G. J. Hinde has kindly examined two slides containing
these bodies, and writes as follows :—

‘They have the appearance, as you say, of intertwining tubules, but 1 do
not detect any definite walls to the tubes, if they are such. Still, it is quite
possible that they might be tubules or canals in which the walls have disap-
peared. They remind me strongly of the structure of the peculiar bodies
from the Carboniferous Limestone of Belgium, described by Prof. Girich, of
Breslau, under the name of Spongiostroma.” Giirich places his forms as
protozoans, but cannot indicate any particular group of Protozoa as nearly
related. Prof. Rothpletz describes somewhat similar bodies from the Silurian
of Gotland and from (sel, and he considers them as hydrozoa.’ *

At several points the limestone of S, shows brecciation. In
Quarry 1 a distinct type occurs, consisting of fragments of horny or
more or less oolitic limestone which reach a length of an inch and
a half, and are united by rather coarsely crystalline calcite. At
other levels the brecciation is on too small a scale to be visible in a
hand-specimen. In the oolitic limestone from the upper part of
S, the grains tend to be relatively large and somewhat scattered :
the centre round which a grain has formad is frequently a foraminifer
(see Pl. XXVIII, fig. 2). Sometimes the concretionary coating of
calcium carbonate is developed round a Seminula in the way de-
scribed by one of us, in the case of the ‘ brecciated pisolite’ of the
Avon section.

S, (¢). These rocks occupy the northern third of the hillside be-
tween Quarries] and 2. Their base is taken as being marked by the
highest chert-band. ‘They are in the main foraminiferal limestones
with bands of Seminula, but are sometimes oolitic and include,
especially in the upper part, very fine-grained, compact, horny
limestone (41)* of china-stone type, but differing from the more

1 Proc. Bristol Nat. Soc. ser. 4, vol. i (1906-1907) pp. 87-100.

* See ‘ Les Spongiostromides du Viséen de la Province de Namur’ Mém.
Mus. Roy. Hist. Nat. Belg. vol. iii (1906) pp. 1-55 & pls. i-xxiii; also Neues
Jahrb. vol. i (1907) pp. 1381-88 & pl. ix.

3 See K. Svenska Vetensk.-Akad. Handl. ns, vol. xliii (1908) No. 5,
pp. 17-20 & pls. v-vi.

* The numerals in parentheses refer to particular spots shown in figs. 3-10
(pp. 354-61) at which important rock-types were obtained,

Q.J.G.8. No. 267. 2B

346 PROF. 8. H. REYNOLDS AND DR. A. VAUGHAN ON [Aug. IgIT,

typical china-stone of the overlying strata in containing numerous. .
foraminifera.

S, (6). This division includes the limestone with chert-bands.
occupying the middle third of the hillside between Quarries 1
and 2.

These limestones are, as a rule, characterized by their highly
foraminiferal and often oolitic nature, but they include in the
upper part some bands of very fine-grained horny limestone of
china-stone type. At (20)—see Pl. XXVIII, fig. 3—occurs.
an interesting rock-type. It consists largely of very irregular,
commonly well-rounded fragments of compact horny limestone,
frequently enclosing a foraminifer or a bit of a crinoidal ossicle, the
whole being united by a cement of crystalline calcite. In this
case, after the penecontemporaneous brecciation of the limestone,
the fragments were rounded, either by rolling or by solution, before
being united in the crystalline matrix. All these various pro-.
cesses were probably quite rapidly carried out.

The most marked feature of the rocks of this horizon is, however,.
afforded by the cherts, of which there are some six bands frequently
associated with bands of Lithostrotcon. In colour these cherts are.
generally pale pinkish-grey. A section cut from one at (17) was
kindly examined by Dr. G. J. Hinde, who confirmed the attribu-
tion of certain rod-like fragments to sponge-spicules, suggesting
that they were parts of the anchoring spicules of hexactinellid
sponges. With regard to certain round bodies which it was.
suggested were radiolaria, Dr. Hinde writes as follows :—

‘The round bodies are small siliceous spheres with a smooth exterior and a
relatively thick wall, enclosing a central area which is now infilled with silica
of a different tint from that of the wall. The wall is traversed by numerous.
radiating straight spines or spokes, which connect the inner area with the
outer surface of the sphere. These seem to me to be really minute pores or
canals now infilled with silica cf the same tint as that of the central area of
the sphere. The spheres are from 0'l mm. to 0°13 mm. in diameter, and
their walls from 0°025 mm. to 0°04 mm. in thickness. Assuming that these-
bodies were originally siliceous, which seems to have been the case, I should.
judge that they are radiolaria,’

Bands full of papilionaceous Chonetes also occur.

S, (a). This band includes (1) the ill-exposed limestone between:
the top of Quarry 2 and the lowest chert-bands, and (2) the lime-
stone exposed in Quarry 2 as far as the prominent rib of rock which
is taken as marking the base of 8,. The upper ill-exposed beds
consist in the main of grey foraminiferal and not markedly oolitic
limestone, but near the edge of the quarry an oolitic character
begins to be apparent.

At (89) a brown bed occurs which is in the main a finely oolitic
limestone, the grains being often formed round foraminifers.
Between the grains is crystalline calcite; and numerous, minute,.
brown patches of associated dolomite and chalybite crystals are’
seen in thin sections to be the cause of the coloration.

Vol. 67.] THE AVONIAN OF BURRINGTON COMBE. 347

A peculiar fault-breccia, consisting of pieces of limestone set in
a very ferruginous matrix, occurs immediately below this slightly
dolomitic band, but is very poorly exposed, It is a noteworthy point
that there are signs of disturbance accompanied by the occurrence
of unusual minerals—in this case fluor, at the corresponding horizon
in the Great Quarry of the Avon section.

The basal beds of S, seen in the quarry are strongly oolitic and
often finely banded limestone, which alternates with fine-grained
grey limestone not obviously oolitic in hand-specimens, but com-
monly shown by thin sections to be so. Crinoids are also an
important constituent of these limestones. Penecontemporaneously
brecciated limestone (3) occurs, similar to that described above at
(20) and below at (111). (See Pl. XXVIII, fig. 4.)

Lowrr Szurnuza Zonz (S,).

Extent.—From the prominent rib of rock near the middle of
Quarry 2, past the end of the quarry as far as Plumley’s Den. Also
the prominent rock-mass on the western side of the Combe, as far as
the cleft known as the ‘ Rock of Ages,’ which is due to weathering
along the same band as is Plumley’s Den.

Thickness.—130 feet.

The prominent rib of rock which it is convenient to take as
marking the boundary between §, and 8, consists of thinly-bedded
and partly dolomitized limestone-bands alternating with thin shaly
partings. The dolomite in this case was probably due to local
infiltration. The main part of 8, consists, however, of rather
thickly-bedded, fine-grained, grey limestone, as a rule obviously
oolitic, and probably oolitic even when this character is not visible
ina hand-specimen. Fine banding is frequent.

Further Account of the Lithology of the 8S, Beds.

Though the great majority of the limestones in §, agree in being
strongly oolitic and foraminiferal, they show a considerable amount
of variability. Some (6) are almost entirely composed of small
and uniform oolitic grains; others (111) are very similar in cha-
racter to the variety described above at (20), consisting of rounded
patches of limestone, sometimes horny, sometimes oolitic, which
have clearly been produced by the brecciation of pre-existing beds—
succeeded in the first place by a more or less complete rounding of
the edges of the resulting fragments, and in the second place by
the deposition in certain cases of successive coats round the frag-
ments in concretionary fashion, followed finally by the union of the
whole in a cement of crystalline calcite (see Pl. XXVIII, fig. 4).

Other rocks again from this level are partly oolitic, partly of
the brecciated type of limestone just described. A considerable
amount of petroleum occurs in the limestone. at the level of
Plumley’s Den and of the cleft in the ‘ Rock of Ages.’ This feature
may be observed at the same level in the Avon section. ,

232

348 PROF. S. H, REYNOLDS AND DR. A. VAUGHAN oN [Aug. IQII,

Uprrer Syrincoruynis Zone (C,). : pil
Extent.—From Plumley’s Den past ‘The Cave’ to the top of

Quarry 3.

Thickness.—320 feet.

In the Avon section this horizon shows a very marked division
into an upper series of shales and dolomites, the ‘ Canznza Dolomites,’
and a lower thick band of white oolite, the ‘ Canimia or Gully
-Oolite.’ In the Burrington section the great thickness of limestone
forming C, shows no such division, but is throughout very uniform,
being almost always oolitic or foraminiferal, or exhibiting the two
characters combined. The upper 150 feet or so, as one passes
southwards from Plumley’s Den, is in the main a very conspicuous
white oolite, and an oolitic character is strongly in evidence at
the base in the higher beds of Quarry 3; but between these points
the limestone is rather foraminiferal (see Pl. XXVIII, fig. 5) than
oolitic, and even in the oolitic limestone foraminifera are very
abundant and frequently form the centres for the larger grains.
Between ‘The Cave’ and Quarry 3, finely broken-up crinoid stems
form an important component of the limestone.

The peculiar type of brecciated limestone with penecontem-
poraneously rounded fragments, already mentioned as occurring in
S, and S, (see Pl. XXVIII, figs. 3 & 4),is met with again at various
points (9, 118, 56) in the upper part of C,,.

“

TOURNAISIAN.

LowER SyRiwGorHYRIs Zonz (C,, including y).

Extent.—From the top of Quarry 3, along the ill-exposed part
of the hillside to about two-thirds of the way down the Great Scarp.
Thickness.—740 feet.

The general succession of the rocks of this level is as follows, in
descending order :—

C, (b). Dolomitized limestone. 240 feet.

C, (a). Fine-grained, grey, generally crinoidal limestone. 350 feet.

y ( Wighly fossiliferous, commonly crinoidal limestone, with much chert.
150 Fine-grained, grey, crinoidal limestone, often highly fossiliferous.
feet. This is identical with the ‘ Petit Granit’ of the Belgian geologists.

Further Account of the Lithology of the OC, Beds.

Although the dolomitization which has taken place at this level
is not so marked as it is in the Avon section, it is still by far the
most important feature of the upper part of C, (see Pl. XX Ve
fig. 6 & Pl. XXIX, fig. 1). The dolomitized rocks } clearly were
originally crinoidal and foraminiferal limestones containing a large
proportion of a calcareous paste or matrix, and it is interesting

‘ Our observations are in close accord with those of Mr. E. E. L. Dixon,
Summary of Progress for 1905’ Mem, Geol. Surv. 1906, p. 48.

Vol. 67.| THE AVONIAN OF. BURRINGTON COMBE. 349

to compare the relative resistance of these several constituents to
the process of dolomitization. The first material to be affected
is the fine calcareous matrix, then the foraminifera are attacked ;
while the pieces of crinoid stem formed of crystalline calcite are
highly resistant, and may remain unaffected when the whole of the
surrounding material is dolomitized.

As regards the conditions of formation of these dolomites, the
facts appear to be in conformity with the now generally accepted
view—that they originated by the practically contemporaneous
alteration of limestone under shallow-water conditions. It is a
well-established fact that shallowing of the water of the Car-
boniferous Limestone sea took place throughout the main part of
the South-Western Province in Middle Avonian times; and the
occurrence of these dolomites on the same general horizon as the
shallow-water beds elsewhere, is evidence that the shallowing
extended to the Mendip area. Below the dolomites is a highly
fossiliferous series forming the remainder of C, and y. The lime-
stones of this level are entirely non-oolitic, and are in the main
fine-grained and dark grey. Corals, brachiopods, and especially
crinoids abound, and sections show polyzoa and foraminifera to be
frequent.

The name ‘ Petit Granit’ is employed by Belgian geologists to
designate a rock mainly made up of larger crinoid - fragments
embedded in a matrix of smaller ones. It occurs commonly in
the y beds and in the upper part of Z, (see Pl. XXIX, fig. 2).

Upon the cherts, which are very prominent, the formation of the
splendid scarp of the upper part of the Combe partly depends.

Upper Z4PHRENTIS ZONE (Z,).

Extent.—The lower slopes of the Great Scarp and the pro-
jecting mass of rock at the bend of the Combe.
Thickness.—140 feet.

Lithologically the Z, beds closely resemble the y beds: differing
in the absence of chert-bands; in the occurrence of shaly partings ;
and in their thinly-bedded character, so that they weather easily.
They consist of dark-grey, generally crinoidal and highly fossili-
ferous limestone, much being of the ‘ Petit Granit’ type.

Lower ZAPHRENTIS Zone (Z,).

Extent.—The main part of the exposures in the valley of
the western twin-stream, from the Goatchurch cave to the road;
and the corresponding series in the eastern twin-stream. Almost
all the southern face of the upper part of the Combe, except just
at the bend, is formed by Z, beds.

Thickness.—140 feet.

A type of limestone similar to that in Z, prevails also in Z..

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Vol. 67.] THE AVONIAN OF BURRINGTON COMBE. 351

‘CLEISTOPORA Zone (K).

Extent.—The whole series between the Old Red Sandstone and
the commencement of the massive limestone of the Zaphrentis Beds.
The beds are exposed in the twin-streams which enter the Combe
from the south. In the western stream the K beds commence at
about the position of the Goatchurch cave. While the K, and lower
K, beds are fairly exposed, especially in the eastern stream, the
upper K, beds can scarcely be seen at all.

Thickness.—500 feet.

The K beds show a greater amount of lithological variation than
any other part of the section, and are the only part of it in which
-grit-bands occur, or in which true shales have auy appreciable
development.

Upper CrersTopora Zone (K,).

Extent.—Ffrom about the level of the Goatchurch cave in the
western twin-stream, or its equivalent position in the eastern, to
above the point where the main hillside path crosses the eastern
twin-stream.

In the western twin-stream the highest exposure of the K, beds
is a fine-grained crinoidal limestone (122) just below the Goatchurch
cave; there is a similar exposure at a little waterfall about 30 yards
higher up, after which the exposures become very bad. In the
eastern twin-stream there are no exposures of the highest beds ;
but, at a point where a minute feeder of the stream (shown in the
6-inch Ordnance map) enters on the east, a fairly continuous section
commences and extends to the base of K,. The rocks consist entirely
of narrow bands of dark crinoidal limestone containing many
brachiopods, alternating with shales which do not as a rule split
well and have often a tendency to conchoidal fracture. In the
lower part of the series are several bands of crinoidal limestone
crowded with polyzoa and small gastropods (see Pl. X XIX, fig. 3),
and comparable to bands occurring at the same horizon in the Avon
section and at Portishead. This polyzoa-band is also seen in the
western stream.

Lowrr CzestoporA Zonet (K,, including Km).

Extent.—In both twin-streams the K, beds may roughly be
said to occupy the stream-course between the upper and the main
paths, commencing at about the level of the main path and passing
down into the Old Red Sandstone at about the level of the upper
jpath.

The lithological variability stated to be characteristic of the K beds
as especially marked in the case of the K, beds. In the eastern

|

302 PROF. 8. H. REYNOLDS AND DR. A. VAUGHAN oN [Aug. IgII,

twin-stream, where the best section occurs, the succession is as
follows (see also fig. 2, p. 350) :—

. Shales.

. Crinoidal limestone with polyzoa, similar to bands in K,.

. Coarsely crystalline limestone with mud-pans.

‘ Bryozoa Bed’ (140)—red, highly crystalline and crinoidal limestone :
about 3 feet.

Coarsely oolitic and crinoidal limestone (139): about 5 feet.

. Thick shale, in places crowded with ostracods.

. Shales alternating with limestone-bands, including one full of small

Chonetes. A grit-band occurs near the base, and below it is a

calcareous band (142) containing crinoids, while immediately below

that is the Old Red Sandstone.

mirc Boost

Further Account of the Lithology of the K, Beds.

In these are several bands of considerable lithological interest.
Band 4, the equivalent of the ‘Bryozoa Bed’ of the Avon and
other sections, is a ferruginous, highly crinoidal limestone (see
Pl. XXIX, fig. 4). Sections show a considerable number of polyzoa,
much iron-stained, and occupying spaces between the crinoidal
ossicles. This horizon has not been detected in the western twin-
stream.

Band 3 is the coarsest and most remarkable oolite oceurring in
the whole section, and is precisely comparable to a band occurring
at the same level in the Skrinkle section near Tenby. The oolitic
grains, which generally are extremely regular, are in the majority
of cases developed round a fragment of a crinoid-stem (see Pl. XXIX,
fig. 5). The rock contains a large proportion of iron-oxide. This
horizon has not been detected in the western twin-stream.

Band 2.—The well-bedded, somewhat gritty shales are commonly
crowded with ostracods, and are well exposed in the eastern twin-
stream. In the western stream ostracods are equally plentiful
in (126) a calcareous grit (see Pl. XXIX, fig. 6), occurring at rather
a lower level.

Summary of the Lithology.
(A) Calcareous Rocks.

Horny limestone, nearly structureless in thin sections, and
concretionary limestone, showing imperfect ‘Cotham-Marble’
structure, are practically confined to the upper part of 8,, although
horny limestone occurs to a slight extent in §..

Oolitic structure.—A band of coarse oolite occurs in the
upper part of K,; but, apart from this, no oolite is met with until
the top of C, is reached. OC, and §, are very largely oolitic; there
is much oolite at the base of S, ; and coarse oolite occurs in the upper
part of S. Most of the oolitic grains show no centre, some are
developed round quartz-grains, many round foraminifera in the
C and S beds, while the very coarse oolite in the K beds has most.

-

Vol. 67.] THE AVONIAN OF BURRINGTON COMBE. 353:

of the grains developed round bits of crinoid-stems. The peculiar
pisolite-breccia is confined to the S beds,

Foraminiferal limestone.—Foraminifera are the principal
limestone-builders throughout C,, 8,, and much of §,. A large
proportion of the oolitic limestones are strongly foraminiferal ;
but, especially in C,, there is much limestone abounding with
foraminifera and yet not oolitic. H. B. Brady, in the Introduction
to his Monograph on the Carboniferous and Permian Foraminifera:
(Pal. Soc. 1876), after referring to various deposits, such as the
White Chalk and the Nummulitic Limestone, as being formed almost
exclusively of the remains of foraminifera, says that in Britain
no portion of the vast series of beds known as Mountain Limestone
has any claim to be placed in the same category, except the
Saccammina Limestone (p. 4). This statement does not hold good
with regard to the rocks at Burrington, some parts of C, being
probably as foraminiferal as the Chalk. As regards the genera of
foraminifera present, Endothyra, Valvulina, and Trochammina
appear to be the commonest, and have been found at numerous
levels from the base of C, to the top of 8,. Tewtularia is the next
commonest, and Nodosari ia has been noted at several levels.

Coral-limestone.—Coral-bands are prominent at the following
levels :—

(a) In D,: where certain bands contain Dibunophyllum and Cyatho-
phylium in abundance.

(4) In §S, and at the base of S,: where Lithostrotion martini occurs in
large masses, and is the main component of thick beds of lime-
stone,

(c) In C; below the dolomitized beds: here Caninia cylindrica is very
abundant.

Brachiopod limestone.—Throughout the Seminula Zones
bands crowded with Seminula are frequent; and, in places, as
near the top of S,, bands composed of giganteid Producti occur.
There is a marked band of papilionaceous Chonetes at the base
of the dolomites of C,. Bands full of Spirifer clathratus and
Chonetes hardrensis are a feature of Z, and Z,. Brachiopods almost
vie in importance with crinoids as limestone-builders in K.

Crinoidal limestone.—Crinoids are the prevalent limestone-
builders throughout K, Z, and C,. They also play an important.
part at the base of D, and C,,

Polyzoa are sufficiently plentiful at certain levels in K, to form
an appreciable constituent of the rock, as are ostracods in e

Dolomite forms the upper part of C,, and local and subsequent.
dolomitization has taken place at various points in the S beds,
probably by the percolation along certain divisional planes of
water containing magnesium carbonate.

Ke)

(L—}

“g hason’y Lo and woddn ayy pun

GP [ sarsunn’y waamjaq oprsyiyy—"E “OUT

fb ampphyoloe? 2292

‘asojoyd “yy ‘HY ‘A

‘adoqoyd "yy "FT 'S

Cay OUT, » 07 wa, Sfimquingy pun g hawongd ysvd “gy fo alnsolvd aprsppry ay) WON — FOI

QAIPAZPY PEP fF

‘a hadon® Maou 02 g hwinn® wou’ ‘spaq *Q pun 'g—

G

Fs)

‘190j04d “YI “ALS

tes of Quarry 3, and the top of Oy.

a

C,, the dolom

Fig. 6.—The base of

S, H, R. photogr,

‘asojoyd “yA ‘S

; ‘k'9 fo duvos 0246 oy, pun
°g hudong “o fo dumos ay) sasiwduos ry ‘spunmyzsow buryoo) “pasianan mar4 — J *Siyq

Fig. 8.—The great scarp of Cf.

[ 359 |

§, H, R, photogr,

a

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)

360 ]

ty

AD
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Vol. 67. ] THE AYONIAN OF BURRINGION COMBE. 36]

(B) Siliceous Rocks.

Chert occurs on three horizons :—

(a) At about the middle of Z).

(>) In the lower part of C,, where the development is very strong.

(c) At about the middle of S,, where again the development is very
strong.

The chert, in most cases, is clearly not an original deposit, but
produced by the subsequent alteration of the limestone. The
corals in §,, C,, and Z, are often replaced by chert, and this
sometimes takes place with the crinoids in Z, while the matrix is

Fiz. 10.—Looking up the valley of the western twin-stream.

; Blackdlowre

——

S. H. R. photogr.

comparatively little affected. On the other hand, it is frequently
observed, though less markedly at Burrington than at some other
localities in the Mendips, such as Waterlip and Windsor Hill, that
in some crinoidal limestones the matrix has been entirely replaced
y chert; while the crinoid-stems have not been affected, and, having
been subsequently removed by solution, are now represented by
cavities. As arule, calcitic organisms, such as crinoids, show greater
relative resistance than arragonitic organisms, such as corals,
whether the metasomatie change is one of dolomitization or of
silicification.
With the exception of these cherts, siliceous rocks are not met

@. J..G. 5. No. 267: 2c

362 PROF. S. H. REYNOLDS AND DR. A. VAUGHAN on | Aug. IQITI,

with anywhere in the section, except very near the base of K,,
where a definite grit-band occurs. Some of the calcareous and

shaly beds at various levels in K, contain a good deal of sandy
material.

(C) Argillaceous Rocks.

These are practically confined to :-—

(a) The K beds, where shales are very strongly developed and contain, in
places, numerous ostracods.

(6) Z, and the top of Sg, where the thin bands of limestone are separated
by appreciable shaly partings.

Shaly partings occur also in connexion with the prominent rib

of rock which is taken as marking the line of division between
S, and §,,.

III. Fauna Lists anp Nores on THE Zonat Favnas.) (A. V.)

Note.—In §§ III & IV repetition of full references is avoided
by the following abbreviations :— :

‘Bristol Paper’ = Q. J. G. S. vol. 1xi (1905) pp. 181-3805 & pls. xxii-xxix—
‘Palxontological Sequence in the Carboniferous Limestone of the Bristol
Area’ by A. Vaughan.

‘Rush Paper’ = Q. J.G.S. vol. lxii (1906). pp. 275-322 & pls. xxix-xxx—
‘Carboniferous Rocks at Rush (Co. Dublin)’ by C. A. Matley &
A. Vaughan.

‘ Loughshinny Paper’ = Q. J.G.S. vol. lxiv (1908) pp. 413-72 & pls. xlix-l
—‘ Carboniferous Rocks at Loughshinny (Co. Dublin)’ by C. A. Matley
& A. Vaughan.

‘Carruthers I’ = Geol. Mag. dec. v, vol. v, Jan. 1908, pp. 20-31 & pl. iv—
Zaphrentis omaliusi, Z. ambigua, and Z. densa.
‘Carruthers II’ = zbid. Feb. 1908, pp. 68-73 & pl. v—Zaphrentis delanouet,
Z. konineki, and Z. konincki, mut. C,.
‘Carruthers III’ = zbid. April 1908, pp. 158-71 & pl. vi—Caninia cornu-
copie and C. aff. cornucopie, mut. D,.,.
These three sections are the commencement of an arduous but

invaluable monograph entitled ‘A Revision of some Carboniferous
Corals’ by R. G. Carruthers.

‘Carruthers IV’ = Q. J. G. S. vol. lxv (1910) pp. 523-37 & pls. xxxvi-

XXXVI.

‘Ed. & H.’ = ‘Monograph of the British Fossil Corals’ by H. Milne

Edwards and J. Haime, pt. iii (1852) pp. 150 et segg. Palzonto-
graphical Society.

‘Nouvelles Recherches’ = ‘Nouvelles Recherches sur les Animaux Fossiles
du Terrain Carbonifére de la Belgique’ Mém. Acad. Roy. Belg.
vol. xxxix (1872) by L. G. de Koninck.

‘Davidson’ = ‘Monograph of the British Fossil Brachiopoda’ by T. Davidson,
vol. ii (1858-63). Paleeontographical Society.

1 It gives me the utmost pleasure to acknowledge the very valuable
assistance that Mr. R. G. Carruthers, F.G.S., of H.M. Geological Survey, has
so ungrudgingly rendered in the identification and study of the Burrington
corals; without his aid, the faunal lists and paleontological section would
have been far less complete.

Vol. 67.] THE AVONIAN OF BURRINGYON COMBE. 363

TOURNAISIAN or LOWER AVONIAN.

CrersTorora Zone (K).
kK, °
The lower portion is an Ostracod-Modiolid phase, capped by the

‘ Bryozoa Beds.’
The upper portion consists of normal limestone-shales.

Corals :—
None recorded.

Brachiopods :—
Chonetes ef. buchiana de Kon., early mutation. Very abundant at the
base of the upper portion, as in the Avon section.
Chonetes cf. laguessiana de Kon. Abundant at certain levels in the

lower portion.
Small Rhynchonellids, in part referable to Camarotechia mitchel-

deanensis Vaughan.
Eumetria sp. and Producius cf. bassus Vaughan are recorded by

Dr. T. F. Sibly.

i:
Only the uppermost part of this subzone is exposed, and that
badly, along the stream in Goatchurch valley.

Corals :—
Zaphrentis delanouet BE. & H., Carruthers. Very rare and only at the
top.
Brachiopods :—

Spiriferina cf. octoplicata (J. de C. Sow.), Rare.
Together with most of the species recorded below at Horizon £.

_ LAPHRENTIS ZONE (2).

Cleistopora being unknown, and Zaphrentis delanoue at least
represented in the uppermost beds just described, it might seem
logical to include the upper part of these beds in Z rather than
in K; comparison, however, with neighbouring areas where the
fauna is better known, together with the change of lithological
character, suggest the division here adopted.

[It would be too hasty a conclusion to infer that the incoming of
Zaphrentis was solely due to the change of conditions represented
by the change of lithology ; for in other localities (for instance,
Llanvaches), where K and Z have a continuous lithological
character, the establishment of Zaphrentis is delayed until ap-
proximately the same time as at Burrington. ‘The facts point
rather to a widespread and zonally-simultaneous introduction by

migration. |
202

364 PROF. S. H. REYNOLDS AND DR. A. VAUGHAN on [Aug.IrgIi,

Horizon £6 (base of Z,).

Corals :—
Michelinia favosa (Goldf.) de Kon., mut. 6. Tall, narrow equal coral-
Amplexus coralloides Sow. lites.

Zaphrentis delanouet BK. & H., Carruthers; and var. Common.
Zaphrentis cf. parallela Carruthers. Rare.

Brachiopods :—

Productus burlingtonensis Hall, mut. 6, Vaughan.

Spirifer clathratus M‘Coy, Vaughan. Abundant; the average dimen-
sions smaller than in Z.

Spirifer ventricosus de Kon.

Syringothyris typa Winchell, Hall. Represented by small and large

forms.
Syringothyris ef. texta Hall.
Athyris 3, Vaughan.
Leptena.
Orthotetes.

Zaphrentis delanouei, to the practical exclusion of other species, is
diagnostic of the level 3 throughout the South-Western Province ;
it disappeared from that province in early Z time, never to return.
The history of the gens in the Scottish Province was, however,
coextensive with Avonian time, and has been dealt with by
Mr. Carruthers in a recent paper.'

Liphrentis vaughani Douglas has not yet been found in any part
of Z in the South-Western Province—a remarkable fact, in view of
the abundance of the species in Lower Z throughout the Belgian

Province, and of its occurrence in beds of that age in County
Clare.”

Zi:
Corals :—
Syringopora 9 Vaughan.
Michelinia favosa (Goldf.) de Kon.
—Laphrentis delanouei EK. & H., Carruthers. Rare.
Zaphrentis omaliusi EK. & H., Carruthers. Typical form only ; common.

Brachiopods :—

Productus burlingtonensis Hall, mut. 3 Vaughan.

Productus aff. pustulosus Phill., early mut. Small forms; the earliest
record is from £ of the Avon section.

Productus cf. semireticulatus (Martin).

Productus ef. niger Gosselet: a species allied to P. bassws Vaughan.

Rare.
Chonetes ef. hardrensis Phill. as interpreted in the
Chonetes cf. laguessiana de Kon., Vauglian. ‘Bristol Paper.
Chonetes cf. crassistria M‘Coy, Vaughan. Very common,

Orthis michelini (L’Kveillé) Davidson.

Orthotetes sp.: the common Z form.

Leptena analoga (Phill.).

Spirifer clathratus M‘Coy, Vaughan = Spirifer tornacensis de Kon.
Very abundant ; increasing in size.

1 ¢ Carruthers LV.’

2 <The Carboniferous Limestone of County Clare (Ireland)’ Q. J. G. S$.
vol. lxv (1909) pp. 549, 577, etc.

Vol. 67.] THE AVONIAN OF BURRINGTON COMBE. 365

Syringothyris ef. texta Hall.
Reticularia aft. lineata (Martin) Vaughan: the Z form.
Athyris aft. glabristria (Phill.) Vaughan: lentiform. Common.

[Fishes :—Oracanthus spine. Psaminodus tooth. ]

Spurfer clathratus is as abundant at this level in the South-
Western Province as it is in Belgium.
f On the other hand, Athyris glabristria is, in the Belgian Province,
almost entirely replaced by A. lamellosa.

Aine
Corals :—

Syringopora 6 Vaughan, and a narrower variant.

Michelinia favosa (Goldf.) de Kon.: walls much thickened.

Michelinia konincki, now. nov., including Rhizopora tubaria de Kon.

Michelinia megastoma (Phill.), mut. Z,. Cleistopora-like aspect.
Common.

Zaphrentis omaliusi E. & H., Carruthers, and its varlant—Zaphrentis
densa Carruthers.

ZLaphrentis konincki KE. & H., Carruthers: long narrow form. Abundant,
and diagnostic of the subzone.

Endophyllum burringtonense, sp. noy. (See p. 377.)

Caninia cornucopie Mich., Carruthers... Common; small.

[Two rare species determined by Mr. Carruthers as Lophophyllum
ef. cortwosum (Mich.) and Amplexus cf. spinosus de Kon. |

Brachiopods :—

Productus aff. cora VOrb. [Recorded by Dr. T. F. Sibly.] Very rare.

Orthis michelini (L’Eveillé) Dav. Common.

Orthis resupinata (Martin). Very rare.

Orthotetes sp.: the common Z form, and a variant with stronger
ornament.

Spirifer clathratus M‘Coy, Vaughan. Not common.

Syringothyris laminosa (M‘Coy) (Dav.): small form. Common.

Athyris aft. glabristria (Phill.) Vaughan: Z, form.

Caninia is now firmly established, although as yet represented
only by small forms belonging to the typical cor nucoptce section ;
the truly vesicular groups are absent.

Zaphrentis densa is gradually replacing the more typical form of
Z. omaliusi,

The Devonian coral, Michelinia favosa, finally disappears at the
top of Z,, and its place is taken by the earliest members of the
megastomatid group—small, flat, plate-like ancestors with few
corallites.

Dr. Sibly’s record of Productus aff. cora is the earliest occurrence
at Burrington of this very long-lived gens. In the Bristol area
this early mutation is well known, and in the Forest of Dean the
history is pushed back at least as far as 6; forward, the gens can
be traced into the Permo-Carboniferous.

366 PROF, 8. H. REYNOLDS AND DR. A. VAUGHAN on | Aug. 1911,

CANINIA Zone (C).—The Mip-Avontan.
Horizon y (base of C,).

The one important change from the Z fauna is the introduction
of the large vesicular Caninids. Speaking in terms of zonal time,
we may say that these large Caninids suddenly and simultaneously
attained dominance from the East of Belgium, across England and.
Wales, to the West of Ireland. In Belgium their history can be
traced back with certainty to late Devonian time, but, even in this,
the country of their birth, it was not until the beginning of C time
that they became the most important factor of the coral fauna.

In y at Burrington the large Caninids are associated in the
main with Z, forms; but combined with these are a few rare, though
highly interesting, ancestors of the incoming Viséan fauna.

Corals :—

Amplexus coralloides Sow., including a very large form.

Zaphrentis densa Carruthers.

ZLaphrentis konincki WK. & H., Carruthers.

Menophyllum tenuimarginatum HK. & H., de Kon.; determined by
Mr. Carruthers. Rare.

Caninia cornucopie Mich., Carruthers: the cornu-bovis stage is fre-
quently well marked. Very common.

Endophyllum burringtonense, sp. nov. : larger forms than in Z,.

Caninia patula Mich., Salée: a cyathophylloid Caninid. Abundant.

Canima densa Salée.

Cyathophyllum (2) 6 Vaughan ; strong Caninoid affinities. Common
and diagnostic of this horizon.

Cyathaxonia cornu Mich. Not common.

Clisiophyllid, an early representative of a C-S gronp.

Brachiopods:—

Productus aff. punctatus (Martin): early mutation, convergent early
Pr. scabriculus.

Spirifer aff. striatus (Martin): early mutation, convergent Sp,clathratus.

Spiriter pinguis Sow. Rare.

Spirifer konincki Dewalque (=Spirifer cinctus de Kon. and auctt.,
non A. de Keyserling). Abundant in one band.

Athyris aff. glabristria (Phill.), and a variant of Seminuloid form.

Athyris aff. lamellosa (L’Vyeillé). Not common ; the dominant Athyrid
in Belgium.

Cyathaxonia cornu and Athyris lamellosa are both greatly more
abundant at y in Belgium. than in the South-Western Province; and
the same remark is true of Spiifer konincki, which is the zonal
index of these beds in Belgium, and there, as in parts of the South-
Western Province, occurs also in Z,. Spirifer pinguis is extremely
common in the Waulsortian phase of this level and C,, both in
Belgium and in Ireland (County Dublin and County Clare).

C,: including a lower series of y type and an upper, dolomitic
series.
Corals :—

Amplexus coralloides Sow.
Zaphrentis densa Carruthers.
Caninia cylindrica (Scouler) Salée. Abundant.

VWall67. | THE AVONIAN OF BURRINGION COMBE. 367

Brachiopods :—
Productus pustulosus Phillips, mut. C; large form. Common at one
level.
Productus cf. semireticulatus (Martin): the Waulsortian form.
Papilionaceous Chonetes.

Chonetes ef. comoides (Sow.): Productoid and Leptznoid groups, the
Productoid group predominating. Abundant at a certain level.
Orthis resupinata (Martin): the typical form. Abundant at one level.

Spirifer sp.: a Waulsortian form. Rare.

Syringothyris aff. cuspidata (Martin): the typical large C form.
Common; the acme of this species is in the Waulsortian phase of
this subzone.

The interest of the foregoing list hes rather in what it suggests,
than in the scanty fauna which it actually enumerates.

In the abundance of large Producti-Chonetes and giant Caninids
we can recall the ‘ Productus-giganteus Beds’ and ‘ serpent-rock’ of
South Pembrokeshire.

In the giant brachiopods (Syringothyris cuspidata, etc.), and in
the long worm-like Ampleaus, we see in very feeble outline the
rich Waulsortian knolls of Belgium and Ireland.

The dividing line between Lower and Upper Avonian in the
South-Western Province has, following the suggestion of Mr. E. E.
L. Dixon, been shifted from its former position, at the base of §,,
to the middle of C; his argument is based upon the fact, which
he has convincingly demonstrated,’ that this was the period at
which emergence gave way to subsidence in the west of the South-
Western Province.

Considered from the faunal standpoint, and with our present
more complete knowledge, there can be no question that the old
system which involved the separation of the top of C from the
bottom of § is unworkable, owing to the earlier introduction of
Lithostrotions and their kin in the west of the Province.

The subjoined table (p. 368) presents the faunal ranges, as they
are now known, with regard to the two lines C,C, and CS. Mere
inspection shows that the upper part of C, must be included with
S,, and that C, must lie below the separating line; but that it is
immaterial from this standpoint where, within the lower part
of C., the division between Upper and Lower Avonian is taken.

The further question of the use of the Belgian terms ‘ Tournaisian’
and ‘ Viséan’ to designate the Lower and Upper divisions of the
Avonian, is complicated by the uncertainty of the division-line in
the Belgian Province itself. As it seems, however,.that the new line
of division in the South-Western Province will practically coincide
with the division between Tournaisian and Viséan at the base of
the ‘Marbre noir de Dinant,’ the Belgian names can be usefully
retained.”

1 «Carboniferous Succession in Gower’ Abs. Proc. G. 8. 1909-10, pp. 72-

3.

2 See H. de Dorlodot, ‘ Relations entre l’Echelle Stratigraphique du Oalcaire
Carbonifére de la Belgique et les Zones Paléontologiques d’Arthur Vaughan,
d’aprés les Recherches les plus réventes’ Bull. Soc. belge de Géol. vol. xxir
(1910) Proc. Verb. pp. 247-90.

way Om cE.

368 PROF, 8. H. REYNOLDS AND DR. A. VAUGHAN ON [ Aug. IQIT,

At Burrington the division-line between C, and C, must be
placed at the top of the laminosa dolomites ; but fossil bands are too
infrequent in the dolomites at the top of C, and in the lower part
of C,, either to confirm or to disprove the abruptness of the faunal
transition.

RanGes oF CorALS AND BrACHTOPODS IN THE M1ip-AVOoNIAN
OF THE SoutH-WesrreRN PROVINCE.

ot

Corals.
LGPNRCIIIS HONINCK. ~~ aerate aerate. |

tarseiCaninids ...0cge) seq ere

CUO phylun G'S ees. A ee | | |
Lithostrotion & Diphyphyllum ......... 2. ew _ ee
Clisiop liye, .ckect ce eee rec? EE

Brachiopods.

Productus corrugatus

Productus hemisphericus

Productus sublevis and \
Productus plieatilis J. de C. Sow. |

iPr odueyCROnCLes ee

SOUT CTE SUPTALU St eee eee ERIE ec.

EL
SPUR CRIClLACRTAUUS, wea. reece ener cae: eee 2 |

Spirifer bisulcatus J. de C. Sow. ...... Titi: ta
Syringothyrts cusprdata .. .....-.s.ee0ees pe cel el
NS CHILI UM ease tater. Me Cee te ee Ee ahs by ee

VISEAN or UPPER AVONIAN.
C5 ce
Lower (and main) portion, up to the White Oolite.

@orals——

Michelinia grandis M‘Coy. Common.

Large Caninids. Not common.

Cyathophyllum @ Vaughan : small form, convergent Zaphrentis konincki,
mut. C,.

Carcinophyllum 6 Vaughan ?: an early mutation. A single specimen.

Brachiopods :—

Productus corrugatus M‘Coy, mut. C,. Abundant at one level.
Papilionaceous Chonetes.

—e

Vol. 67.] THE AVONIAN OF BURRINGTON COMBE. 369

Syringothyris cuspidata (Martin) : the large C form.
Seminula ef. ambigua (Sow.): a distinct variant or new species. Com-
mon at a level discovered by Dr. Sibly.
Seminula ? gregaria (M‘Coy) (a doubtful reference). Not uncommon.
[Gasteropods are abundant at certain levels :—Huomphalus and
Bellerophon. |

We here notice the initiation of two important Viséan gentes,
Cyathophyllum aff. murchisoni (represented by its progenitor C. ¢)
and Carcinophyllum @ (leading on to Lonsdalia), as well as the
establishment of Productus aff. corrugatus and of Seminula ;
the last-named genus is represented by two peculiar species that
have a greater importance in the North-Western Province—now
for the first time sinking beneath the Carboniferous Sea.

C. :
Upper portion: the White Oolite.

Corals:—

Cyathophyllum ¢ Vaughan : typical form.
Chetetes (?) tumidus (Phill.) E. & H.

Brachiopods :—

Productus corrugatus M‘Coy, mut. C,.

Productus @ Vaughan. Very abundant at the top.
Productus ef. sublevis de Kon. Rare.

Productus ef. concinnus Sow. Common.

The rare swblevis-like forms of Productus merely suggest their
enormous abundance at this level in Belgium and Northern France.
The White Oolite is remarkably constant in position and fauna,
wherever the peculiar conditions of the Seminula Zone are about to
follow (Belgium, Northern France, South-Western Province, North-
Western Province.) In certain areas, however (as, for example,
South Pembrokeshire), the whole of C, is faunally continuous with
the Lithostrotion Beds above, and it is best to class C, and §,
together as one division—the C-S Zone. On the other hand, in
areas where the Waulsortian or knoll phase is developed (parts of
Belgium and Ireland), it is often very difficult to separate C, from C,,.

SEMINULA Zone (8).
Si:
Corals :—

Lithostrotion martini EB. & H. Common.

Carcinophyllum mendipense Sibly. Not uncommon.

Productus corrugato-hemisphericus: a group composed of more than
one gens.

Spirifer cf. swavis de Kon. (?).

Athyris ef. expansa Day., non (Phill.).

Athyris ef. paradoxa (M‘Coy). Not rare: very broad fringes.

Athyris ingens de Kon.

Seminula sp. Rare.

Camarophoria isorhyncha (M‘Coy). Rare.

al ~

370 PROF. 8. H. REYNOLDS AND DR. A. VAUGHAN ON [Aug. IQIT,

At Burrington, where large Caninids are absent, it is not easy to
distinguish §, from the overlying beds ; the occurrence of Cyriima
carbonaria (M‘Coy) is here taken, for convenience, to mark the base
of S,. The lower limit of S, is also artificial, being taken at the
first observation of Lithostrotion.

The assemblage :—Athyris inyens (= Athyris cf. glabristria
Sibly), Camarophoria isorhyncha, Carcinophyllum mendipense, at
the base of Quarry 2 suggests the Milton-Road level of Dr. Sibly’s
Weston paper.’ [This assemblage is also found at Cheddar,’ but
there the level must be a little higher than at Burrington, for I
have found Cyrtina carbonaria to be a common associate of the
above-mentioned forms at Cheddar. The distance above the White
Oolite in the two cases tends to confirm this view. |

S.: the main Seminula Zone.

Corals :—

Cyathophyllum aff. murchisoni KE. & H.: an aberrant and rare variant.
Lithostrotion martini EK. & H. Abundant.
Carcinophyllum 6 Vaughan. Common.

Brachiopods :—

Productus 9 Vaughan. At the bottom.

Productus corrugato-henvisphericus, including Pr. cora, mut, 83, Vaughan.
Common.

Papilionaceous Chonetes. Common.

Seminula ficoides Vaughan. Common throughout.

Cyrtina carbonaria (M‘Coy). Common only at the bottom, but ranges.
through.

Productus giganteus (Martin), mut. D,. Only at the top.

The Seminula fauna is very limited in species, but remarkably
abundant in individuals; bands composed almost entirely of
Lithostrotion, Productus, Chonetes or Seminula, succeed each other
and repeatedly recur through the zone. Considering how exclusive
this fauna is, it is remarkable how widely it is spread, for it is the
standard fauna of this period in Belgium and Britain, and we do
not yet know its phasal equivalents.

DIBUNOPHYLLUM Loxe (D).
D,: the only part of the zone uncovered at Burrington.

Corals :—

Cyathophyllum murchisoni BK. & H. Abundant.
Diphyphyllum sp., convergent Koninckophyllum @ Vaughan.
Dibunophylium ¢ Vaughan. Common.

Brachiopods :—

Productus giganteus (Mart.), D, mut.
Productus hemisphericus J. de C. Sow. Abundant.
‘ Orthotetes’ cf. senilis (Phill.).

Athyris cf. expansa Dav., non (Phill.), mut. Dj.

1 Q. J. GS. vol. Ixi (1905) p. 560.
2 Ihid. vol. lxii (1906) p. 357.

Vol. 67.] THE AVONIAN OF BURRINGION COMBE. 371

This fauna agrees with that of D, at all other points of the South-
Western Province, and is closely similar to that of the same level
in the North-Western Province near the top of the Great Scar Lime-
stone. It is, in fact, astonishing how close is the resemblance of
the South-Western and North-Western Provinces at this horizon.

iD,

This division—the top of the Carboniferous Limestone in the
Bristol Area—is covered by Triassic rocks in the syncline between
Burrington and Wrington, but must be continuous with the fine
exposure of fossiliferous beds in the quarry overlooking Wrington.
The fauna of these beds is described in the ‘ Bristol Paper’.! These
beds may be correlated with the top of the Great Scar in the North-
Western Province, where they are capped by the Yoredales, to which,
in the South-Western Province, there is no fossiliferous equivalent
except in Gower.”

IV. Panxontotoey. (A. V.)

(1) CORALS.
Michelinia.

The two forms of greatest interest both occur in Z,,.

MicHELINIA MuGASTOMA (Phill.), mut. Z,.

This form has as yet no specific name, although its abundance in
many, and widely separated, districts at the same level makes it an
important zonal fossil.

The corallum is circular with a flattened base; the calicinal
surface is gently convex.

The corallites have large, approximately equal, apertures, and are
some ten in number.

The walls of the calices are thick and almost vertical ; the calices
are deep, so that there is little room between floor and epitheca for
the development of vesicular tissue, and the internal structure is
almost entirely concealed by the growth of stereoplasm.

The epitheca is concentrically wrinkled, without roots.

This mutation is common in Z, at Burrington, Stackpole Quay,
Malahide, ete.

There can be little doubt that this mutation passes up into the
typical IZ. megastoma, a species that has its maximum in C-S, and
only differs from the Z mutation in greater size and in the propor-
tionately larger number of corallites.

The megastoma beds of Rush (C-S) contain the typical M/. mega-
stoma in abundance.

At Burrington the place of M. megastoma is taken by M. grandis,
and the rule seems to be generally true that M. megastoma and
M. grandis are, to a considerable extent, mutually exclusive.

Q. J.G. 8. vol. lxi (1905) p. 242.
Abs. Proc. Geol. Soc. 1909-10, pp. 72-73.

&
i -
: |

L
2

342 PROF. S, H. REYNOLDS AND DR, A. VAUGHAN ON | Aug. 1911,

MIcHELINIA KONINCKI, nom. nov. (A single corallite is figured—
Pl. XXX tig. 4.)

= M. grandis, mut. Z.
= M. tenuisepta Ed. & H. and de Kon., non (Phill.).

This species is the most distinctive of all the Michelinias, and
is splendidly figured by de Koninck (as MW. tenuisepta)1; Hd. & H.
pl. xliv, fig. 1 is also a good representation.

The tall corallites are few in number ; their apertures are large,
and do not differ very markedly in size.

These two characters distinguish the species immediately from
M. tenwisepta (Phill.), figured by me in the Loughshinny paper,
p. 456. I have consequently assigned to it a new specific name.

The corallites, on account of their slight adhesion, are commonly
found separate—a vertical section of one of these isolated tubes is
figured in Pl. XXXI, fig. 4, and shows the vesicular structure of
Michelinia.

M. konincki probably passes up into M. grandis M‘Coy, a tall,
large-apertured species abundant in C-S. M. grandis is not un-
common in C, at Burrington; it abounds in the North-Western
Province at Arnside, Kendal, etc., and it was from this province
that the type-specimen was derived.

Zaphrentis.

ZAPHRENTIS DELANOUEI Ed. & H., Carruthers.
Identical with ‘ Carruthers II’ pl. v, fig. 6.

At Burrington this species is abundant at @ and rare in Z ;
there is no record of its occurrence above this level at any point of
the South-Western Province. It occurs in Z—y, both at Malahide
and at Tournai. Ihave no personal knowledge of its occurrence in
the Viséan, although a form transitional towards 7. enniskillent is
found in C-S of Arnside.

ZaPHRENTIS Cf. PARALLELA Carruthers. (Pl. XXX, figs. 1 a-16 &
(?) figs. 3 a—3 6.)

Compare ‘ Carruthers IV’ pl. xxxvii, figs. 4 a4 d.

This form is larger and more regularly conical than the abundant
and typical Z. delanouet, with which it is associated.

The fossula in the adult (fig. 16) is remarkably parallel-sided
and contracts at the apex—cf. Carruthers’s fig. 4a; the septation
is, however, more Caninoid than in his figures.

[ Figs. 3a & 36 are sections of a coral closely similar, externally,
to the above, but much mineralized by beekite; it is possible that
this may be aCaninia, although comparison with figs. 1a & 16 suggests
that it is merely a badly-preserved example of Z. ef. parallela.|

The species is rare in (§, at Burrington, where I do not know it
at any other level.

' “Nouvelles Recherches’ pl. xiii, figs. 2 & 2 a.

Vol. 67.] THE AVONIAN OF BURRINGION COMBR. 373

ZAPHRENTIS OMALIUST Ed. & H., Carruthers.
Identical with ‘Carruthers I’ pl. iv, figs. 1-4.

At Burrington this species is abundant in Z,, not uncommon in
Z, and at y, but has not been found above y.

In the South-Western Province generally, Z. omaliust enters as a
very small and very rare form in §; in Z, it is not uncommon; it
abounds in Z, and y, and ranges on into C..

Neither here nor elsewhere do I know of the occurrence of the
typical species in rocks of Viséan age.

ZAPHRENTIS DENSA Carruthers. (Pl. XXX, fig. 2.)
‘Carruthers [’ pl. iv, figs. 7 & 8.

At Burrington, Z. densa is rare in Z,, equally common with
Z. omaliusi at y, and common, after the disappearance of that
species, in C, above y.

Our figure compares well with Carruthers’s fig. 7, and is a
horizontal section of a typical specimen from C,, just below the
dolomite.

The passage of Z. omalius: into Z. densa, suggested by Car-
ruthers, is an established fact at Burrington and in the South-
Western Province generally.

ZAPHRENTIS KONINCKI Ed. & H., Carruthers.
‘Carruthers IL’ pl. v, figs. 1-4 a.

At Burrington this species, in a narrow, cylindro-cornute form,
abounds in Z, and is common at y, but has not been found at any
higher level. A specimen from the base of Z, has shorter minor
septa.

No example of the C, mutation, convergent with Cyathophyllum 9,
has yet been discovered at Burrington, although common at many
points of the South-Western Province, at Arnside, ete.

Caninia.

The following species of Caninia are represented at Burrington,
at the levels stated :—

Caninia cornucopié Mich., Carruthers—Z, and y.
C. patula Mich., Salée—y.
C. cylindrica (Scouler) Salée—C,.

CANINIA CORNUCOPLA Mich., Carruthers.
Refer to ‘ Carruthers ITI.’

Mr. Carruthers has given so excellent an account of this species
that my notes need be but brief.

At Burrington the species enters in Z,, is abundant at y with
C. patula, but disappears before the incoming of C. cylindrica.

In Z,, only the Zaphrentis stage is exhibited ; at y, the amplexoid,
or ‘ cornu-bovis’ stage is not infrequently observed. At no point of

og a

o7/t PROF, 8. H. REYNOLDS AND DR. A. VAUGHAN ON | Aug. IQII,

the South-Western Province did C. cornucopia ever attain the large
size or abundance that makes this species so important an index of
Z,-C, throughout the Belgian Province. Dr, Salée records the
species from Z, (Calcaire de Landelies), where it is not common.

Caninza PatuLa Mich. (Pl. XXX, figs. 5 a—6 b & text-fig. 11.)
H. Michelin, ‘ Iconogr. Zooph.’ 1840-47, p. 255 & pl. lix, fig. 4.
L. G. De Koninck, ‘Nouvelles Recherches’ p. 87 & pl. viii, fig. 2
(Zaphrentis patula).
A. Salée, ‘Le Genre Caninia’ Brussels 1910, p. 39 & pls. vi-viii.

Externally, our specimens accord best with Michelin’s figure,
except that minor septa are not visible within the calyx as in his
type-figure. In this respect, L. G.de Koninck’s figured calyx exactly
resembles the few specimens that I have been able to collect with
well-preserved calices. Since Dr. Salée, of Louvain University, has
given so detailed a description of this species, and has illustrated it
by such a wealth of figures, there will be no need to do more than
note a few peculiarities of the Burrington specimens.

This species is characterized by its fossula, wide vesicular ring,
and septa continuous to the walls (so that no peripheral zone of
large vesicles is developed). The septa are, at least partly, thickened
by stereoplasm ; this thickening affects all the septa in the young
(see Pl. XXX, fig. 5 a), the two cardinal quadrants only (see fig. 6 a),
or is limited to a lining of the fossula (see fig.5 6). In a region of
thickened septa there is an inner wall, formed of thickened arcs
stretching from septum to septum; this is usually absent on the
counter-fossular side.

There are at Burrington two forms or varieties, which differ
only in degree ; they may be defined as widely and closely septate
respectively. The widely-septate form is the abundant one, and is
represented in Pl. XXX, figs.5a &5b. Fig.5a shows the young
stage, in which vesicles are undeveloped, the septa are thickened
throughout, and the counter-septum is elongated, Fig. 56 is an
adult, in which stereoplasm is practically absent, and the vesicular
ring is remarkably Cyathophylloid. It is worthy of note that
vesicles first form on the counter-side, so that the ring is much
wider on this side (see text-fig. 11, p. 375).

Minor septa are undeveloped, either in this or in the closely-
septate variety, and herein lies the main difference from all the
specimens figured by Salée; it may be that this difference is
mutational. ;

Figs. 6a & 66 represent the closely-septate form, which is chiefly
remarkable for a curious flexure of the tabule; this peculiarity is
indeed met with in the widely-septate form also, but is there less
common. A contoured plan of such a tabula is represented in text-
fig. 11 (p. 875), from which the general character is obvious :—A
narrow, flat-bottomed fossular valley is bounded laterally by almost
vertical walls and behind by a steep slope; having ascended this
slope we find ourselves on a broad, flat plane. Proceeding towards
the north across this plane, we encounter a second steep bank that

¥ol.67.) THE AVONIAN OF BURRINGTON COMBE. 370

abuts sharply against a vertical wall, built up of vertically elongated
vesicles (represented diagrammatically in the figure).

As might be anticipated from the uniplanar curvature, the
symmetry of the young cornute stage is essentially bilateral; on
the other hand, that of the adult cylindrical stage tends to become
radial.

Fig. 11.—Contoured plan of one of the characteristic tabule of
Caninia patula, Mich. x 2:7 diameters. (Drawn from silicificd
specimens occurring in y at Burrington Combe.)

[The outer ring of vesicles is diagrammatically shown, and the septa
are omitted. |

The ranging of this gens under Caninia rather than under
Cyathophyllum is a matter of personal preference, for it cannot be
maintained that so typical a Cyathophyllum as C. murchisoni does
not occasionally exhibit both a distinct fossula and stereoplasmic
thickening. ‘The most characteristic feature, however, of Oyatho-

\ phyllum—the presence of a marginal ring of small vesicles within
the central area—is lacking in Caninia patula. On the other hand,
the development of an amplexoid stage—so distinctive a feature of
Canina cornucopie—is also lacking in Caninia patula.

It is impossible to consider C. patula to have been derived from
either C. cornucopie or C. cylindrica, and in my opinion its marked
peculiarities warrant the creation of a new genus.

376 PROF, S. H. REYNOLDS AND DR. A. VAUGHAN ON [ Aug. IQIT,

Occurrence.—At Burrington, and at other points of the South-
Western Province that have been carefully revised, Caninia patula,
in the mutation (?) that has no minor septa, is diagnostic of y.

In Belgium the typical Caninza patula ranges to my personal
knowledge through C,, but I have seen it nowhere else. (The
precise horizon of Dr. Salée’s figured specimens is not stated.)

It is possible that C. bristolensis Vaughan (= C. cylindrica,
mut. S, Vaughan) may be a member of the gens C. aff. patula as
suggested by Dr. Salée (op. ct. p. 33); C. bristolensis has, however,
the following very marked characters that ally it with C. cylin-
drica mut. C,, and distinguish it from C. patula :—

(1) The septa are strongly developed only within the inner wall, and are
all much thickened in the adult stage.

(2) The prolongations of the septa through the vesicular area are very
irregular in their course and very faintly developed, suggesting late
acquisition of the structure.

(8) These prolongations are, in places, discontinuous ; and in such regions
large vesicles are developed, resembling those of C. cylindrica.

(4) The minor septa project inwards beyond the vesicular ring as short
teeth thickened by stereoplasm, exactly as in C. cylindrica.

(5) The vesicular ring is composed of an inner zone of fine, closely-packed
vesicles, and a broader outer zone of coarse irregular structure.

In confirmation of his suggestion Dr. Salée remarks (p. 46, op.
cit.) that he has never observed, in any coral, the acquisition of
small vesicles following a stage characterized by large ones. This
contention is, however, definitely disproved in the case of Caninia
cylindrica mut. C,, where the transition is clearly demonstrable (see

below, under C. cylindrica).

CaNInIA cyLinpRIcA (Scouler) Salée. (Pl. XXXI, fig. 1.)
A. Salée, ‘Le Genre Caninia’ Brussels 1910, pp. 27-39 & pls. ii-iv.

Dr. Salée has given so excellent an account of this species, and
has illustrated it by such majestic figures, that I have contented
myself with a single figure showing the highest stage of develop-
ment reached in C, at Burrington—the only level, at that place, at
which the species is known with certainty.

The earlier stages are exactly as figured by Dr. Salée in pl. iii of
his monograph, namely :—

(1) A ‘cornucopie’ stage—strong bilateral symmetry, no vesicles, short
minor septa, pennant-like majors.

(2) A ‘cornu-bovis’ or amplexoid stage—short thickened majors and short
minors, broad central tabular area, peripheral vesicles irregularly
developed at thickened rings and absent at constrictions.

(3) ‘cylindrica, mut. y’ stage—septa, both major and minor, prolonged
outwards for a short distance from the inner wall so as to produce a
narrow ‘external’ area, beyond which they extend discontinuously as
projections from the large peripheral vesicles (see Pl. XXXI, fig. 1). |;

In C, and later forms in other parts of the South-Western
Province, mutation proceeds simultaneously along two lines :-—

(a) The septal prolongations extend from inner to outer walls, traversing

the whole vesicular area.
(6) The fossula becomes diminishingly conspicuous, with the result that

a Campophylloid stage is acquired.

all ao i

Vol. 67.] THE AVONIAN OF BURRINGTON COMBE. 377 |

No specimens illustrating this mutation have been found at
Burrington, where Caninia is not definitely known above C..

It is interesting to point out that in Belgium, where the gens
probably originated, stage 2 (v.s.) is the highest stage reached in
Z, (Calcaire de Landelies).

Endophyllum priscum (Minster) Frech,’ from the lower part of
the Upper Devonian, is a Caninid that reaches the stage 2. The
early stages, however, of this coral resemble those of the next
described species, and it cannot therefore be regarded as a member
of the gens of C. cylindrica.

It is interesting to notice that similar stages in coral development
can be observed in other gentes not closely related to Caninia
cylindrica. In fact, the four stages of development :—

(1) Septa without vesicles ;

(2) Endophylloid stage—large peripheral vesicles, septa not prolonged
outwards ;

(3) ‘ cylindrica’ stage—septa produced outwards for a short distance only,
large peripheral vesicles ;

(4) Septa produced to wall ;

are well exhibited in the Carcinophyllum-Lonsdalia progression :—

Stages
(1 © 2) Zaphrentoid Carcinophyllum—major and minor septa thickened at
wall so as to be in contact, large peripheral vesicles present only at
certain levels. C. mendipense from C-S.
Stage
(2) Carcinophyllum typical—major and minor septa projecting from a
thickened inner wall, peripheral vesicles always present, septa not
produced outwards. Carcinophyllum @ from 8S, and D,.
(Compare Pl. XXXI, fig. 5—a specimen from the lower part of 8,.)
Stage
(3) ‘Lonsdalia cf. floriformis’ types—inner wall formed of fine crowded
vesicles, septa prolonged outwards for a short distance, forming a
narrow ‘external’ area; large peripheral area.
Lonsdalia floriformis from D,.

We may also note that Carcinophyllum is essentially a simple
coral (I have only seen two compound specimens in a long experi-
ence), whereas Lonsdalia is essentially compound, illustrating
the general law that compound forms are preceded by
simple ancestors

Endophyllum Ed. & H., Frech.
Zeitschr. Deutsch. Geol. Gesellsch. vol. xxxvii (1885) p. 76.

ENDOPHYLLUM BURRINGTONENSE, sp. nov. (Pl. XXX, figs. 4 a—4c.}

Irregularly-bent, vermiform coral with strong annularthickenings.
The major septa are thickened only at the wall and do not
reach the centre, but leave a clear central area occupied by tabula

1 Zeitschr. Deutsch. Geol. Gesellsch. vol, xxxvii (1885) p. 76, pl. vii, fig. 2
& pl. x, figs. 2, 2a—c.
2 See Rep. Brit. Assoc. 1909 ON ets) p- ee

Q.J.G.8. No. 267. 2D

378 PROF. 8, H, REYNOLDS AND DR. A. VAUGHAN oN [Aug. 1911,

alone. A third of the septal ring is composed of a group of
straight, longer septa which do not meet one another ; the remain-
ing two-thirds of the ring are formed of shorter curved septa, that
meet internally to build up a continuous inner boundary to the
septal ring.

Minor septa are practically absent in the young stage (Pl. XXX,
fig. 4a), but in later stages (fig. 4 6) they become a conspicuous and
diagnostic feature; at the rim of the calyx they equal in promi-
nence the majors.

The tabule occasionally stretch completely across the vertical
section without interosculation; but the majority of the tabule
split, so as to form broad cushion-like vesicles (Pl. XXX, fig. 4c).
All the tabule bend down at the wall.

Vesicles are developed only in the adult stage, and especially
at the thickened rings and on the convex side (fig. 4 c—the vesicles
present on the convex side have been accidentally blocked out in
the print); these vesicles are vertically elongated, and shift the
septal base-line inwards.

In the absence of the earliest stage, which is probably cornute,
the position of the fossula is difficult to fix; it probably lay
opposite the longer septa, although the tabule are apparently
depressed on that side.

Comparison with Amplewus cornu-arietis de Kon.
‘Nouvelles Recherches’ p. 72 & pl. vi, figs. 4, 4a.

The external characters—form and calyx—of the Burrington
species present a strong general resemblance to L. G. de Koninck’s
figures, although it is difficult to believe that his figures are both
views of the same specimen. In his description at p. 72 of the
text, that author mentions a deep fossula—a fact that immediately
separates his species from ours, and suggests that Mr. Carruthers
is right in including Amplexus cornu-arietis as a synonym of
Caninia cornucopic.

Comparison with Endophyllum priscum
(Minster) Frech.

The cross-section of the young stage of EH. priscum’ is almost
identical with fig. 4a of our Pl. XXX, and the tabule are of the
same nature.

The development of vertically-elongated peripheral vesicles in the
adult is on the same plan as in our species—although the degree
of development is very much greater in Prof. Frech’s figure, and
separates the two forms specifically.

The habit that the septa often show in E. priscum, of leaning
against one another, is also exhibited in certain adult sections of
E. burringtonense.

There can be no question that HE. burr piglen rise and £. proscwm
are distinct species of the same genus.

i Zeitschr. Deutsch. Geol. Gesel'sch. vol. xxxvii (1885) pl. x, fig. 2,

Se ge Sarin ek

a

Vol. 67.] THE AVONIAN OF BURRINGTON COMBE, 379

Occurrence.—Endophyllum burringtonense occurs in Z, and y
at Burrington, and the y forms are markedly larger than those
from Z,. The same form occurs in the Rush Slates of County
Dublin and in y of Malahide.

Cyathophyllum.

CyarHopHYLLUM(?) @ Vaughan. (Pl. XXXI, fig. 2: a calicular
view.)

A horizontal section of a young form is figured in the Bristol
Paper, pl. xxiii, fig. 2. It is much easier to describe this striking
coral than to assign it to a particular genus.

In the adult, there is an external ring of fine vesicles, crossed
by equally distinct major and minor septa.

The major septa extend to the centre, where they become
flexuous, and one of them is strengthened to form a conspicuous
ridge.

The walls of the calyx descend steeply from a sharp rim; the
floor of the calyx is vaulted in the middle to form a tall conical
peak, crested by the strengthened septum. As remarked above,
the long septa climb this peak somewhat spirally.

The earliest stage has no vesicles and presents a Caninoid type
of septation.

The fossula is strongly developed at all stages on the Caninia-
like plan.

As a mere description, Cyathophyllum appears to be more

satisfactory than Caninia, since it implies the actual plan of the
septation and the biseptate external ring of vesicles ; furthermore,
Cyathophyllum murchisoni frequently exhibits a fossula precisely
like that of our species. That the species had a Caninoid ancestor
seems, however, clear.
_ The elevation of the peak is extremely variable, though always
noticeable. The external form is a typical, wide-angled horn, and
the epitheca is nearly smooth. The vertical section shows clearly
the incoming of the vesicles, at some little distance from the tip.

This species occurs at only one level within y. I know it from
other points of the South-Western Province, but never from any
other horizon; it is common at Burrington.

I owe the fine figured calyx to Mr. H. F. Barke, of Bristol, who
extractéd the coral from a mass of limestone by immersion in
acid.

CYaTROPHYLLUM MuURCcHISoNI EKd.& H. (PI. XXXI, fig. 6.)

This section suggests relationship to the Diphyphyllum figured
in the same Plate (fig. 7); but the resemblance is deceptive and
accidental. The two rings of fine vesicles separated by a ring of
more open texture, are at once determinative of Cyathophyllum, and
the central tabulate area is an abnormality confined to a portion
only of theindividual. This kind of abnormality is even commoner
in the simple forms of Cyathophyllum regium, in which there are

2D2

380 PROF. 8. H. REYNOLDS AND DR. A. VAUGHAN ON [Aug.1gri,

normally no tabule. Such a phenomenon may perhaps find a
parallel in the unwinding of the most highly-developed ammonites,
The specimen is from the upper part of §,.

Diphyphyllum.
Dirpuypuyiium sp. (Pl. XXXI, fig. 7.)

It is difficult to decide to which of the following genera to refer
this fine coral :-—

Campophyllum Ed. & H., emend. Carruthers.
Koninckophyllum Nich. & Thoms.
Lophophyllum Ed, & H., emend. Carruthers,
Diphyphyllum M‘Ooy, emend. Vaughan.

Campophyllum is never columellate.

’Koninckophyllum is best confined to strongly columellate forms,
with a thick external area made up of closely-packed
vesicles, and with minor septa projecting (as in Letho-
strotion) beyond the vesicular ring.

Lophophyllum, as figured by Mr. Carruthers,’ differs very markedly
from our species in the insignificance of the minor septa
and in the highly-developed central structure in the adult.

Our form is practically non-columellate, although consecutive

tabulee are occasionally ridged in the centre, when a crest is formed
which reaches from tabula to tabula. This phenomenon is highly
characteristic of Diphyphyllum, to which genus I have referred the
species. |

It is not unlikely that our form is a direct descendant of

Diphyphyllum subibicinum (M‘Coy), a species which has its
maximum in C-S and ranges through 8; variation must be
assumed to have resulted in increased thickness and packing of
the external ring, and in the occasional ridging of the tabule.

The Burrington form occurs at D,, and is convergent with

Koninckophyllum 6.

Clisiophyllid.
An early CutstopHytiip. (Pi. XXXI, fig. 3.)

The central area is composed of a thick plate, surrounded by
three or tour strong concentric intersections which are crossed
by short, thin, discontinuous lamelle.

The major septa are thick and moderately spaced. The minor
septa are equally thick, short but prominent. All the septa are
attached to the wall by their thickened ends, and practically no
vesicles are developed.

Judging from similar forms in C and C-S, the columella with its
thin coating of vesicles projected as a tall, laterally compressed

1 ©A Carboniferous Fauna from Nowaja Semlja..... with Notes on the
Corals by R. G. Carruthers’ Trans. Roy. Soc. Hdinb. vol. xlvii (1909) pp, 152
et seqq. pl. i, figs, 1-2 d.

ee iin tie ek de ai aa a el eae Le

Vol. 67.] THE AVONIAN OF BURRINGTION COMBE, 381

spike from the floor of the calyx. (Very similar forms are known
from C-S of the South-Western Province, the North-Western
Province—Arnside, etc., County Dublin, etc.)

The figured section agrees well with fig. 2a, pl. xxx of the
Rush Paper from C-S* (Rush Conglomerate or megustoma beds),
and possibly our species is actually an earlier member of the same
gens ; the only essential difference consists in the fact that a thin
external ring of vesicles is developed in the Rush species, and is
absent from our Burrington form.

The figured specimen was found at y; its damaged state
prevented me from founding a new species.

(2) BRACHIOPODS.
Chonetes.

I. The small Chonetes of the Lower Tournaisian :—

Chonetes cf. buchiana.
Chonetes cf. crassistria. | As interpreted in the
Chonetes cf. hardrensis. Bristol Paper.
Chonetes cf. laguessiana. |
(The degree of approximation denoted by ‘cf.’ is, in all four
cases, one of general aspect only.)

CuonerEes cf. BucHIANA is figured by Davidson (‘ Day.’ pl. lv,
fig. 12).

Shell small, convex, non-transverse ; ribs coarse and often forked
at the margin. A concentric ornament composed of minute folds,
which is still seen in the under layer, but is not usually impressed
on the cast.

The resemblance to Ch. buchiana de Kon. of the Upper Viséan
(D) consists solely in the similarity of ribbing; the D species is
traisverse, with a broad rolled beak.

It is necessary, therefore, to separate this form from Chonetes
buchzana under a new specific name; I propose Ch. stoddarti, in
commemoration of the late W. W. Stoddart, of Bristol, who collected
the specimens studied by Davidson.

Occurrence.—This species appears to be very local in its
distribution, fer it only occurs abundantly in the Avon and at
Burrington. It is only known in K..

1 In the Rush Paper (pp. 276-77) the following correlation of the con-
tinuous sequence—Rush Slates, Rush Conglomerate or izegastoma beds, Carlyan
Limestone—was made :—

and

Carlyan Limestone
C.-S,
megastoma beds.

Bush Slates ........ iain
J

Although this correlation was called in question (pp. 441-42) in the sub-
sequent or Loughshinny Paper, it has now been amply confirmed and the
apparent difficulties explained.

382 PROF. &. H. REYNOLDS AND DR. A. VAUGHAN on [Aug. 1911,

CHoneTes cf. cRAssISTRIA is figured in pl. xxvi, fig. 2 of the
Bristol Paper.

This small Chonetes has the general form and convexity of
Ch. ef. hardrensis, but differs in the strength and spacing of its
ribs. There is a fine concentric striation that, in the more
coarsely-ribbed forms, is as obvious as in Ch. stoddartt.

Occurrence.—Common in K and Z, of many localities in the
South-Western Province, but rare at Burrington.

CHonetes cf. HARDRENSIS Phill., Dav. (‘ Dav.’ pl. xlvii, fig. 22.)

Shell small, convex, non-transverse, and finely ribbed, with a
small number of hinge-spines.

Distinguished with difficuity from small Chonetes that are
abundant in Upper D of the North of England and Scotland.

At Burrington, as in the South-Western Province generally, this
species crowds the surfaces of beds in Z, and occurs more rarely in
the Upper Tournaisian ; it is practically absent from the Viséan.

CHoneres cf. LAGUEssIANa is figured in pl. xxvi, fig. 1 of the
Bristol Paper.

Shell flattened, transverse, rectangular, finely and closely ribbed.

Cardinal region almost perfectly flat; the rest of the surface
very gently flexed. Cardinal spines numerous.

Occurrence at Burrington.—Abundant at certain levels
in K, and common in Z,.

II. The large Chonetes of the Upper Tournaisian :—

Cuonetes cf. comorpEs of the Bristol Paper includes two distinct
forms, agreeing in large size and massiveness with Chonetes
comordes Sow.

(1) A large Productoid form, excusably confused with Productus
guganteus.

The muscular field of the convex valve is that of Chonetes,
and not of Productus; there are no accessory adductors as in
Daviesrella.

The development of this giant Chonetes seems to have been
carried out within the South-Western Province, for there ‘is
continuous increase in size and convexity (but essential agreement
in other traits) onward from Z,, where the gens is first recognized.

The Z, mutation is rare, but conspicuously larger than the
abundant Ch. cf. hardrensis ; it is essentially distinct in form from
Ch. cf. laguessiana.

There is of necessity some difficulty in unravelling the history
of the gens below Z,, for further diminution of size would result
in a small form so like Ch. cf. hardrensis as to require most minute
discrimination.

Occurrence at Burrington.—Common at the bottom of
the C, dolomite, and at the same level in the South-Western
Province generally.

Vol,,.67:] THE AVONIAN OF BURRINGTON COMBE. 383

(2) A large geniculate (Leptenoid) form with a flat cardinal
region.

The form that has just been described has a strongly convex beak
and beak-region ; the present form is equally large and even more
massive, but has a flat cardinal region occupying half the valve,
the rest of the valve being gently flexed. The shell is markedly
transverse.

Although the immediate ancestors of this form are unknown, it
is not improbable that Chonetes cf. laquessiana is an early ancestor,
for reduction in size and massiveness by parallel development with
the first-described form would result in just such an ancestor as
Ch. cf. laquessiana.

Occurrence.—The development of this Leptznoid form was
probably carried out in the Pembroke area, where it reaches its
greatest abundance; it becomes less abundant when traced east-
wards, and, in Belgium, the discovery of a rare example was
recorded and described by M. P. Destinez.*

At Burrington this form is a rare associate of the Productoid
form described above. In other parts of the South-Western
Province it is, as already stated, much commoner, and reaches its
acme in C,.

The Relation between Syringothyris and Spiriferina.

SYRkINGOTHYRIS LAMINOSA (auctt.) non (M‘Coy). (Pl. XXXI, fig. 8.)
Spirtferina laminosa de Kon., Ann. Mus. Roy. Hist. Nat. Belg. vol. xiv,
pt. 6 (1887) pp. 103-105 & pl. xxii, figs. 44-50, pl. xxx, figs. 30-31.

Range.—Z, and C..

External characters.—The general aspect is that of a
large Spiriferina, with a well-developed area and coarse ribs. As
in Spiriferina, there is a delthyrial callus extending for a short
distance only from the apex. The shell is punctate, as in both
Spirtferina and Syringothyris.

Internal characters.—Wholly or partly buried within
this callus is an infilled syrinx that can be seen half projecting
along the middle line of the callus and, in weathered specimens,
is represented at the apex by a short narrow rod.

A cross-section near the beak shows the infilled syrinx and the
two dental plates; at a little distance below the beak the strong
mesial septum begins to appear.

In these two characters :—

(1) The presence of a syrinx,
(2) The late development of a mesial septum,
consists the claim of the species to belong to Syringothyris.

Comparison with the genotype of Spiriferina—

A cross-section of Spiriferina rostrata, from the Middle Lias, at

the beuk shows the absence of a syrinx and the immediate appear-
ance of the mesial septum.

* Ann. Soc. géol. Belg. vol. xxix (1901-1902) Bull. p. 106.

eS eee rrr—c ee ?

384 PROF. 8. H. REYNOLDS AND DR. A. VAUGHAN ON [Aug. IQII,

Comparison with Syringothyris subconica (Mart.),
from the D Zone.—S. subconica is so similar to S. laminosa
that its specific separation has been viewed with scepticism.
There seems, indeed, to be no reasonable doubt that S. subconica
is the direct descendant of S. laminosa, and differs only in the
accentuation of traits already adumbrated in the earlier form.

A cross-section of the beak of S. subconica reveals the characters
of Syringothyris as typically developed as in S. cuspidata (Mart.)
itself. Hence S. laminosa develops, phylogenetically, into a
typical Syringothyris.

The problem consequently seemed to have been satisfactorily
solved, and the separation of Spiriferina from Syringothyris was
reduced to the rubbing down of the beak :—

If the mesial septum appears at once, without a trace of syrinx:—
Spiriferina.

If the mesial septum is delayed, and there isat least a primitive syrinx :—
Syringothyris.

Comparison with Carboniferous ‘ Spiriferinas’ has reopened the
problem. This investigation is as yet incomplete, but the results
obtained indicate the close relationship in Carboniferous time of
the two genera Spiriferina and Syringothyris. For example :—

In Spiriferina octoplicata (J. de C. Sow.), which is common in
the D Zone, the appearance of the mesial septum is retarded, and
there are Syringothyroid characters in the cross-section.

In Sporiferina peracuta de Kon., common in early Z in Belgium,
the mesial septum is a mere ridge. (The cross-section has not yet
been studied.)

The most probable guess is, that Spiriferina and Syringothyris
were both derived, at much the same time, from a common ancestral
group, aud that they developed on different lines, but that, in the
earliest period of their history, they possessed the same essential
structure.

The figured specimen, from y of Burrington, shows the syrinx
on the rubbed-dowr beak.

History.—An early mutation occurs at 6 (see below); S. sub-
conica is the D mutation.

SPIRIFERINA cf. ocropricaTa (J. de C. Sow.), Vaughan, ‘ Bristol
Paper’ pl. xxvi, fig. 6.

Occurrence.—K and 6 of the South-Western Province ; rare
at Burrington in K..

The small shells included under this head, from the South-
Western Province, probably comprise two species :—

(1) An early mutation of Syringothyris laminosa, discussed
above. Compare figure of young form, de Kon. op. cit.
pl. xxu, figs. 49-50.
This completes the history of the gens S. laminosa in the
Avonian.

Vol. 67.] THE AVONIAN OF BURRINGION COMBE. 385 >

(2) Spiriferina peracuta de Kon. op. cit. pp. 101-102 & pl. xxi,
figs. 56-61.
This species is very abundant in Z, of Belgium; the specimen
figured in the Bristol Paper is probably the same.

Comparison with Spiriferina octoplicata (J. de C.
Sow.).—Sp. peracuta has tall and narrow ribs, the furrows being
relatively broad; so that a cross-section of a single valve lying on
its ribs is castellated with narrow slits. The cardinal angles are
never rounded, and the hinge-line is the greatest width of the
shell.

Sp. octoplicata has ribs and furrows equal and similarly angular,
so that the cross-section, made as above, is sharply maxillate. The:
hinge-line is often shorter than the width of the shell, and the
cardinal angles are then rounded.

The history of Spiriferina in the Avonian is as yet unknown.

V. (a) PuystogRAPHIcAL ComPARIsoNn oF THE BuRRINGTON SEQUENCE
WITH THAT AT OTHER POINTS oF THE SovuTH-WESTERN AND
Bexeran Provinczs. (A. V.)

These two provinces may be considered to form together a single
large province, to which the name Bristol-Dinant Province
will be applied.

Pre-Avonian. (Old Red Sandstone.)

Burrington, in common with the whole South-Western Province,
formed part of a great inland lake, whereas the Belgian Province
and North Devon were covered by the Devonian Sea.

Km.

In the South-Western Province, fresh water gave place to very
shallow marine conditions.

In the Belgian Province, the sea became shallow. Hence in Km
conditions became similar over the whole Bristol-Dinant Province.

In North Devon a Carboniferous fauna was evolving in the
Productella-productoides Beds of the Pilton Series.

This is the base-line of the Avonian and the bottom of the
Cleistopora Zone. :

K, and Ky.

The Carboniferous fauna became established throughout the
South-Western Province, whereas Km conditions persisted in
the Belgian Province.

This portion of the sequence is consequently classed as Carboni-
ferous in England, but as Devonian in Belgium. Since it is a
matter of impossibility to separate our K beds from Z under two
distinct formations, whereas it 1s merely a conventional division in
Belgium, we may hope that the young Belgian geologists will come
into line.

Fig, 12.—The relation of Burrington to other Carboniferous Limestone districts.

BELGIUM.

o. W. PROVINCE.

N. W.

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Vol. 67.] THE AVONIAN OF BURRINGTON COMBE. 387

It is worthy of note that the thickness of K traced northwards
from Burrington does not diminish as it does in later zones, on
account doubtless of different configuration of the shore-line.

B (base of Z).

Standard conditions (encrinital limestones and shales) became
continuous over the whole Bristol-Dinant Province, and the
Zaphrentis fauna was established.

In the uppermost Pilton Beds of North Devon, the fauna is
essentially a @ fauna with a few persistent Devonian forms.

This is the period of greatest extent of the Bristol-Dinant Province,
and has been selected as the datum-line for the vertical sections
in fig. 12 (p. 386).

It is the base-line of the Belgian Carboniferous and of the Tour-
naisian of the Belgian writers (an unfortunate fact, since we cannot
therefore in strictness include the K zone in the Tournaisian).

Z.

Standard conditions prevailed generally over the Bristol-Dinant
Province, and there is a noticeable diminution of thickness both
towards the north from Burrington and Dinant, and towards
the east from the South-Western Province to that of Belgium.
Furthermore, North Devon emerged, and formed the southern
boundary of the Bristol-Dinant Bay. ‘The variation of thickness
clearly points to a northern and eastern shore.

[The disproportionate thickening of Z at Burrington and Wau!-
sort is caused by the oncoming of C, conditions (see below) at the
top of Z.]

Dolomite is developed towards the northern and eastern shore-
lines (for instance, nearly the whole of Z is dolomitized in the
Chepstow area north of Burrington, and in the Namur area north
of Dinant).

C).

Indications of a shallowing sea are universal throughout the
Bristol-Dinant Province, and this is the period of greatest diversity
of deposit.

Two types of deposit dominate the sediments, namely :—

(1) The coarsely-crinoidal or ‘ Petit-Granit’ type, with the knoll or
Waulsortian type as a variant ;

(2) Dolomite.

At Burrington there is a great thickness (625 feet) of the Petit-
Granit type followed by dolomite (375 feet).

Unfortunately, only the lowest and highest parts of the Petit-
Granit division are well exposed. At Waterlip, however (south of
Burrington and on the southern flank of the Mendips), where the
development is practically identical in thickness with that at Bur-
rington and agrees exactly where the two series can be compared,

388 PROF. S. H. REYNOLDS AND DR. A. VAUGHAN ON [ Aug. IQII,

the rocks have been extensively quarried. Besides beds made up
almost entirely of crinoidal débris, there are many levels at which
deposits of a knoll-like nature can be observed, although the most
characteristic features of Waulsortian rocks are apparently absent.

At Waulsort, the knoll type is magnificently developed, and
at Ecaussines there is an equally fine display of the typical * Petit
Granit.

That deposits of this type were rapidly accumulated is clearly
shown in fig. 12 (p. 386) by the Te erate expansion of C, at
Burrington | and at Waulsort.

The Dolomite.

As we pass northwards from Burrington or Dinant, dolomites
gradually replace the lower, Petit Granit division, until the whole
of C, is represented by dolomite, as in the case of the Grande
Dolomie of Namur. The consequent diminution in thickness is
strikingly brought out in fig. 12.

The Viséan (C-S, S and D).

Since we are only concerned here with differences within the
Bristol-Dinant Province, there is no need to dwell upon the Viséan
sequence, for the deposits are remarkably similar at the same levels
throughout the Province. There is a diminution in thickness of
each zone northwards and eastwards as in the Tournaisian, and
doubtless due to the same cause. In D of the South-Western Province,
Clisiophyllids are abundant at all points; in Belgium, however, corals
are rare except between Liége and Dinant. (They are, nevertheless,
abundant in the North-East of France near Avesnes.)

[In the foregoing account I have omitted all reference to Visé,
at which corals of D species abound; the Visé limestone is an
example of the British Midland type, unique so far as Belgium
is concerned; it rests unconformably upon, or is faulted against,
typical Devonian. |

For comparison with the Bristol-Dinant Province, a vertical
section of the Ingleborough sequence is included in fig. 12 (the
data were kindly furnished by Mr. Cosmo Johns). This section
illustrates the two points in which the North-Western Province
differs from the South-Western, namely :—

(1) The omission of lower zones—here the Tournaisian is wanting.
(2) The expansion of D—here due to the development of Yoredales.

* Prof. H. de Dorlodot, of Louvain University, restricts the term Petit
Granit to a deposit made up of large crinoid-fragments embedded in a matrix
of smaller fragments, with the fur ther condition that the deposits must be
of C, age. I have ventured to use the term in a broader sense, for rocks made
up almost entirely of large crinoid-fragments, even though their matrix be in
part a fine calcareous mud,

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Vol. 67.] THE AVONIAN OF BURRINGTON COMBE. 389

(5) Comparison or THE Upper Patmozorc Corats with THE LowzrR
Patmozorc GRAPTOLITES, IN REGARD 10 OccuRRENCE, DisrkI-
BUTION, AND Kvotution. (A. Y.)

(i) The coral and graptolite-bearing beds, respectively lime-
stones and mudstones, in their typical development build up rock-
masses of great thickness and lithological uniformity—the layers
that are actually fossiliferous forming but a small proportion of
the whole mass. Both coral-limestones and graptolite-shales can
alike occur intercalated in a series of typically arenaceous deposits ;
and, furthermore, both groups of fossils are occasionally found in
indisputably shallow-water deposits.

(ii) Corals and graptolites share the disadvantage of being rare
or absent in certain types of deposit.

(iii) Within each successive zone, certain genera of corals are of
world-wide distribution, and the time taken to bring about this
geographical expansion was, reckoned zonally, insignificant.

Of such widespread genera we may notice :— Zaphrentis, Litho-
strotion, and the Clisiophyllids (both simple and compound).

As examples of the zonal contemporaneity of faunal history we
may cite the following :—

Lithostrotion (both massive and dendroid) enters in the early
Viséan in North America, Britain, and Belgium.

Lonsdalia characterizes the uppermost Viséan of Tian-Shan,
Belgium, and Britain.

The coral indices occur in the same order wherever they are
known ; and, in the majority of cases, knowledge of the zonal series
in one area will unravel the succession in another. As examples
may be cited the coral sequences in Belgium, Northern France, the
South-Western Province, and the area described by Prof. Garwood.

The truth of these statements when applied to graptolites has
long been recognized and utilized, since it was first pointed out in
the classical publications of Charles Lapworth.

(iv) If, however, of two zonal stratigraphers, working inde-
pendently in two different areas, each drew up the series of zonal
indices best suited to his own area, the two series would probably
differ in two particulars, namely :—

(1) The number of zones would differ according to the variability or
uniformity of the rocks and, in rough proportion to this factor, according
to the extent of the area studied.

(2) The actual indices employed would differ specifically, although the
genera employed would usually be in accord.

These facts are patent in the case of the graptolites, if we com-
pare the zones suggested for Bohemia, Scania, Lakeland, North
Wales, and South Wales.

In the case of the corals it 1s sufficient to examine the time-scales
drawn up by Prof. Garwood and myself.

(v) Evolution.—It is evident that, when the history of all the
dominant gentes of any fossil group has been definitely established,
the co-occurrence of known mutations of several of these gentes

390 PROF. 8. H. REYNOLDS AND DR. A. VAUGHAN ON [ Aug. IQII,

places the age of a bed beyond dispute—this is, indeed, the one
impregnable method of zoning.

In the case of the Carboniferous corals, a splendid start has been
made by Mr. Carruthers, and, in this paper, I point out the main
stations along some other important lines of coral evolution.

Among the graptolites Dr. Marr, followed by Miss Elles,’ has
pointed out several evolutionary lines which have a striking proba-
bility ; the suggested series, however, await the confirmation that
can only be assured by the determination of the ratios which two
successive mutations bear to each other numerically, from the date
of earliest occurrence of the second mutation up to the time when
it, entirely replaces the first.

(vi) The lines of evolution in the graptolites and in
the Paleozoic corals.—aAs has been explained by Dr. Marr, the
eraptolites progressed along two directions and in two stages :—

(1) by the numerical reduction of similar parts ;
(2) by the increase of structural complexity in the remaining parts.

This method of evolution is strictly comparable with that of
mammalian dentition.

Furthermore, the greatest ‘ generic’ variation took place auante
early periods. Again this agrees with the case of the early Tertiary
mammals.

In the Paleozoic corals, viewed broadly and as a whole, the first
stage finds a parallel in the reduction of fossule resulting in the
development of radial from quadrantal symmetry. ‘The second
stage is, however, the most important in the case of the corals, for
structural complexity, at the end of the Lower Carboniferous, rose
to a high pitch, resulting in a maze of so-called genera among the
Clisiophyllids.

Thus, in the graptolites, the greatest ° generic’ variation took
place at the beginning of their history—in the corals, at the end.

Reviewing all the foregoing facts, we see that extensive distri-
bution and constancy of zonal sequence are characters shared alike
by corals and by graptolites—both lowly organisms. Furthermore,
the corals with which we are concerned inhabited a narrow strip

along the shore-line: adult, the animal was sessile; young, it was
at the mercy of currents, and it is at this stage that migration
was rapidly effected.

The commonly accepted view that graptolites, either of themselves
or as passengers, lived in the open sea seems to need stronger
testimony than has yet been adduced, especially in view of the fact
that rapidity of variation is a phenomenon usually associated rather
with the fluctuating conditions of in-shore life, than with the
monotonous sameness of oceanic existence.

QUART. JOURN. GEOL. Soc. VoL. LXVII, PL. XXVIII.

Fia. 2.

S. H.R., Photo.) [Bemrose Collo.
AVONIAN OF BURRINGTON COMBE.

QUART. JOURN. GEOL. Soc. VoL. LXVII, PL. XXIX.

S. H.R., Photo.) {[Bemrose Collo.
AVONIAN OF BURRINGTON COMBE.

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AVONIAN CORALS From THE BURRINGTON SECTION (ME

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(ALL FIGURES MAGNIFIED 13.)

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QUART. JOURN. GEOL. Soc. VoL. LXVHE: Pe. X¥XE

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Bemrose Ltd. Collo., Derby.

J. W. Tutcher, Photo.

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AVONIAN CORALS From THE BURRINGTON SECTION (ME

WITH ONE BRACHIOPOD.

Vol. 67.| THE AVONIAN OF BURRINGION COMBE. 391

EXPLANATION OF PLATES XXVIII-XXXI.
Puate XXVIII.
[Fig. 6 is magnified about 25 diameters, and all the others about 15,]

Fig. 1. Concretionary limestone showing what appear to be interlacing tubules
(? calcareous alga) (31). S, top; Quarry 1. (See p. 345.)
2. Oolitic and foraminiferal limestone (33). 8, top; Quarry 1. (See
p. 345.)
3. Penecontemporaneously brecciated horny limestone (20). S,; hill-
side between Quarries 1 & 2. (See p. 346.)
4, Penecontemparaneously brecciated oolitic and foraminiferal limestone
(3). S, base; Quarry 2. (See p. 347.)
5. Foraminiteral and crinoidal limestone (12). O,; near the Cave. (See
p. 348.) é
6. Limestone in process of dolomitization (182). C,; Quarry 3. (See
p. 348.)

Prats XXIX,

[Fig. 6 is magnified about 25 diameters, all the others about 15.]

Fig. 1. Limestone in process of dolomitization G49) 5 Ge Quarry 3. The

. unaltered limestone is grey, the dolomite black in the photograph.
‘he white patches are holes in the rock-slice due to faulty prepara-
tion. (See p. 348.)

. Crinoidal limestone (‘ Petit Granit’) (63). C,; hillside between
Quarry 3 and the Great Scarp. (See p- 349.)

. Crinoidal limestone with gastropods (124). K,; western twin-
stream. (See p. 351.)

. Crinoidal and bryozoan limestone (‘Bryozoa Bed’) (140). K, ; eastern
twin-stream. (See p. 352.)

. Coarse oolite (139). K,; eastern twin-stream. (See p. 352.)

. Calcareous grit with ostracods (126). K,; western twin-stream, (See
p- 352.)

bo

Oo Be os

Piatt XXX, |

[All the figured specimens are from the Burrin gton section, and are
magnified 12 times. ]

Figs. 1a & 10. Sections from the same specimen, Zaphrentis cf. parallela
Carruthers (p. 372). From Horizon f. fl

Fig, 2. Zaphrentis densa Carruthers (p. 373). From C.. )

Figs. 3a & 3b. Sections from the same specimen ? Caninia sp. or ¢ Zaphrentis
ef. parallela (p. 372). From Horizon £.

Figs. 4a-4¢. Endophyllum burringtonense sp. 10Y. (p. 877) ; fig. 4a, the small
form from Z,; figs. 4b & 4c, from Horizon y.

Figs.5a & 5b. Caninia patula Mich., de Kon., & Salée (p. 374). The widely-
septate form. From Horizon y.

Figs.6a & 60. Caninia patula Mich., yar. (p. 3875; see also text-fig, 11,
p. 375). The closely-septate form. From the base of Horizon y,

°

Puate XXXII.

[All the figured specimens are from the Burrington section Figs. 1, 2, and6&
are of the natural size ; the others are magnified 13 times. ]

Fig, 1. Caninia cylindrica (Scouler) Salée (p. 376). From Or.
2. Cyathophyllum (%) @ Vaughan (p. 379). From Horizon y:
3. Early Clisiopbyllid (p. 380). From Horizon Y.

392 THE AVONIAN OF BURRINGTON COMBE. [Aug. 1911,

Fig. 4. Michelinia konincki nom. nov. = M. tenuisepta de Kon., non (Phill.)

(p. 372). The vertical section of a disconnected corallite from Lx

5. Carcinophylium @ Vaughan (p. 377). From the lower part of §,,.

6. Cyathophyllum aff. murchisont K. & H. (p. 379). An aberrant variant
from the top of §,.

7. Diphyphyllum sp., convergent Koninckophyllum @ (p. 880). From D,.

8. Syringothyris laminosa (de Kon.), non (M‘Coy) (p. 883). | From
Horizon y.

Discussion.

Dr. T. F. Sisty congratulated the Authors on their detailed
revision of this magnificent section. In the description of the
section published by him in 1905, the faunal divisions recognized
were substantially those maintained in Dr. Vaughan’s Bristol paper.
But later researches had greatly modified that original classification,
and certain alterations were very conspicuous in the case of this
section. He drew special attention to the change in the delimitation
of Zones Z& C. Horizon y, as originally defined by Dr. Vaughan,
was characterized by the abundance of Caninia cylindrica, and was
recognized as an horizon of faunal overlap between the two zones.
But this horizon, so clearly defined in the Burrington sequence, was
now placed high up in C,, the designation ‘ Horizon y’ being trans-
ferred to a much lower level characterized by Caninia patula. At
the same time, Zone C became greatly expanded at the expense
of Z.

With reference to the Seminula Zone, and the relatively very
small thickness of 8, as here defined by the Authors, the speaker
enquired what was the precise evidence relied on for separating §,
from 8,. This zone was much better displayed in the Cheddar
Gorge than at Burrington. At Cheddar, only 2 or 3 miles distant,
a typical 8, fauna occurred some 300 feet above the base of the
zone, and S. was little, if at all, inferior in thickness to §,. A
remarkable fact, in his ‘opinion, was that this Upper 8, horizon at
Cheddar showed a strong development of chert and an abundance
of Lithostrotion martini in silicified masses, features identical with
those of certain beds in the Burrington section included by the
Authors in their §,.

With regard to the generic position of ‘Syringothyris’ laminosa,
he mentioned that he had recently collected some well-preserved
internal casts of this shell from C in the Mitcheldean district. These
specimens showed no trace of a true syrinx, but exhibited a peculiar
modification of the mesial septum in the pedicle-valve.

Prof. Garwoop also spoke, and Dr. Vaucuan briefly replied on

behalf of the Authors.

Vol. 67.] THE CULM OF SOUrH DEVON: EXETER DISTRICT. 393

14. Noves on the Cutm of Sour Devon: Parr I—Exerer Disrricr.
By Freperick Geores Cotitns, F.G.S. With a Report on
the Puant-Remarns, by E. A. Newert Arser, M.A., F.LS.,
F.G.S.; and Nores on Carpontrerous Ceruaxopopa from the
Nerenpournoop of Exsrer, by Grorer C. Crick, Assoc.R.S.M.,
F.G.8. (Read June 14th, 1911.)

[Prats XXXTI—Mar. |

ConTENTS.

Page

EF TRGB ie ate aS cocoa ns en dans cacancodacsccecee 393

NW rear ares eee ook oes cis wa badass onvereee, 394
TIT. Previous Records of Fossils .................... ope Neen Ba 394 |
Py) hae Or, Hasume ane ParaiGeg 2: ele 396 |
Vo peri on the Pest emai coos cap nenecseschcete nessa 398
VI. Notes on Carboniferous Cephalopoda from the Nee nboee ,

Bi pstehe coer ee Pee ee 8 oi io te ha eel wean 399

I. Lyrropvuction.

Some ten years ago, my friend Mr. C. Davies Sherborn pressed
upon me the desirability of making a thorough examination of the
Culm Measures of South Devon, and promised every assistance
in his power if I would undertake the task. He pointed out that
a great part of the area was practically unexplored, and, if syste-
matically worked, might yield results that would fix exactly the
position of the beds in the Carboniferous System.

The sequel has shown the soundness of his judgment. But,
living on the spot, I knew well the reputation of the beds. To
quote some recent writers, Mr. E. A. Newell Arber says :-—

‘From a palzobotanical standpoint the Culm Measures offer a most un-

. promising field ..... ; ltis nowadays a matter of the greatest difficulty to obtain
specimens sufficiently wel. preserved to admit of satisfactory determination.’ !

Principal A. W. Clayden writes :—

rey. [the Exeter type of Culm Measures] are singularly devoid of recognizable
ossils.’ *

Occasional essays of my own at collecting had but confirmed me in
a similar opinion. However, I at length undertook a more syste-
matic search for fossils than appears to have hitherto been made.
Since then my schoolboy son Oliver and I have spent much of our
leisure in patiently searching the Culm rocks of the neighbourhood,
and the examination of a definite line of country having now been
completed, the time has arrived to publish the results thus far
obtained.

1 Phil. Trans. Roy. Soe. ser. B, vol. exevii (1905) p. 294.
2 «The History of Devonshire Scenery’ 1906, p. 53.

@.7J..G. 8: Noe= 267, QE

394 | MR. F. G. COLLINS ON THE CULM [Aug. 1911,

Il. Lirerature.

The city of Exeter stands almost at the eastern extremity of the
southern outcrop of the Culm Measures, and therefore it is not
surprising that the earlier literature, which naturally is concerned
with broad and general views of the formation as a whole, contains
scarcely a reference to the beds under consideration. Had fossils
been found in any number, doubtless the district would have com-
pelled attention as time went on; but the order of succession has
been fought out mainly elsewhere.

In the Geological Survey Memoir on ‘ The Geology of the Country
around Exeter’ 1902, the Culm Measures are classified litholo-
gically by Mr. Ussher, and the only fossils recorded are Posedonomya
bechert and two goniatites called Glyphioceras sphericum and
Gl. crenistria (pp. 9 & 15).

Dr. Wheelton Hind, in vol. ii of his monograph of the Carboni-
ferous Lamellibranchiata (Pal. Soc. 1901-1905, p. 174) and in
Proc. Geol. Assoc. vol. xxi (1910) p. 463, speaks as if the age of
the Devon Culm were well-known. But it is clear that he really
refers to the age of the North Devon beds, because he only mentions
the Waddon-Barton area of the south. The fossils from Waddon
Barton were long since described ; and, so far as I and my advisers
are aware, no collections of fossils have ever been made and no lists
have yet been published for the southern Culm area of Devon. It
is also clear from Mr. Ussher’s memoir (1902) that no material
from this southern area, beyond the three fossils which he records,
was available to the Survey officers when the memoir was published.

III. Previous Recorps oF Fosstts.

The earliest mention that I have found of Culm fossils from this
neighbourhood is contained in Phillips’s ‘ Figures & Descriptions of
the Paleozoic Fossils of Cornwall, Devon, & West Somerset’ 1841.
In the preface to that work (p. vil) the author says
‘and lately Mr. Drury of Exeter has favoured me with the sight of some of
the goniatites which have been found near that place.’

These would appear to have been all of one species, as it is only of
Goniatites inconstans that the locality is quoted as ‘near Exeter
(Mr. Drury’s cabinet).’*

In 1842 R. A. C. Austen [Godwin-Austen] mentions Gonzatites
mivolobus and G. crenistria, and also the following plants : Pecopteris
lonchitica, Neuropteris heterophylla, Sphenopteris latifolia or acuti-
folia, Cyclopteris sp., and Calamites, as occurring in South-East
Devon,” but he gives no further particulars of locality.

1 J. Phillips, ‘ Figures & Descriptions of the Paleeozoic Fossils of Cornwall,
Devon, & West Somerset’ 1841, pp. vii, 123-24 & pl. li, fig. 238.

2 «On the Geology of the South-East of Devonshire’ Trans. Geol. Soc.
ser. 2, vol. vi, pt. 2 (1842) pp. 461-62.

Vol. 67.| OF SOUTH DEVON: EXETER DISTRICT. 395

Dr. Thomas Shapter, writing in 1842 (‘ Climate of South Devon’
p. 173), says :—

‘This formation contains many vegetable impressions, of which the chief
are Cyperites bicarinata, Pecopteris lonchitica, the knots, apparently, of a
Sigillaria, and a great variety of Calamites, as well as Goniatites, and other
marine fossils. These usually occur in somewhat flattened concretionary
nodules, which are found both in the soft and hard beds, and in many cases
seem to have constituted nuclei, around which the oxide of iron, alumina,
iron pyrites, and other minerals of which they are composed, have collected.
The neighbourhood of Pinhoe, near Exeter, has been very productive in these
fossils ; they have also been discovered in the same range of hills on the south-
eastern side of the Exe, near Oakford Bridge on the Creedy, at Cleeve, near
Newton St. Cyres, and near the Okehampton road, about 5 miles from Exeter.’

In the second edition, published twenty years later, the following
paragraph (p. 79) is added to the foregoing :—

‘In the upper beds of this series, at Pinhoe and Cleeve, casts of the beautiful
Goniatites inconstans occasionally occur with numerous little fossils about the
size of a large shot, which have been regarded (Parfitt) as the eggs of a marine
animal.’ [Probably young goniatites. |

In the Royal Albert Memorial Museum at Exeter there are a few
Culm fossils, presented many years ago by the Devon & Exeter
Institution. Those of them which came from the neighbourhood
of Exeter have been named by Mr. Crick, and comprise :—

(1) A solid goniatite found in a pebble [nodule ?] near Cowley Bridge,
Exeter. J.T. Underhill.
Glyphioceras phillipsi Foord & Crick.
(2) A solid goniatite, No. 6834, locality unrecorded.
Glyphioceras inconstans (J. Phillips).
(5) Eight smali goniatites, No. 4541, labelled ‘ Exeter. J.T. Underhill.’
Dimorphoceras (? discrepans Brown sp.).
Glyphioceras striolatum (J. Phillips).
(4) Pwo goniatites labelled ‘Dunsford Road, above Pocombe Bridge, Exeter.
J.T. Underhill.’
Glyphioceras reticulatum (J. Phillips).
Glyphioceras striolatwm (J. Phillips).

The collection of the late W. Vicary contains some specimens of
goniatites, which are thus mentioned in the Survey Memoir :—

‘Reference has been made to evidences of close connection amounting to
a passage from the shales and grits of the Exeter type downward into the
Basement beds. In Mr. Vicary’s collection, Goniatites labelled from three
localities in which there are no signs of the occurrence of characteristic
Basement beds point to this. The localities are Cocktree Moor, near North
Tawton, on the southern border of the New Red Valley of Crediton in Sheet
324; near Pinhoe Church in raddled shales and grits; in the cliff by Bonhay
Road, Exeter. The writer visited Pinhoe and the Bonhay Road section re-
cently, but beyond occasional plant-traces his search was unrewarded by the
discovery of fossils.’ }

The Champernowne Collection, recently acquired by the
authorities of the British Museum, contained no Culm fossils
from this district.

1 W. A. E. Ussher, ‘The Geology of the Country around Exeter’ Mem.
Geol. Surv. 1902, p. 16.
2u2

396 MR. F. G. COLLINS ON THE CULM”: [Aug. 191i,

IV. Lisr or Fosstrs ann Locatirrus (see Map, Pl. XXXII).

It will be seen from the foregoing pages that fossil records are
not numerous. This is the less remarkable when we remember
that what Mr. Ussher terms the ‘Exeter type’ of Culm rock is
unsuitable for building or road-metalling, and that consequently
quarries are few and far between. In the absence of both quarries
and coast-sections, the fossil-hunter has to rely, as we scon found,
upon hedge- and stream-sections and the surfaces of ploughed fields.
But, while perfect specimens are indeed rare, fossils are abundant
in many localities, and frequently have their characteristic ornament
beautifully preserved. The plants, however, are so fragmentary
that, as Mr. Arber states, it is often difficult or impossible to
determine species.

It was decided to begin the search on the south-west and north-
east line running through the city of Exeter, along which the Culm
rocks disappear beneath the New Red Series. Subsequently, the
work was extended at each end of the line: on the south-west to
the confines of Dartmoor, and on the north-east to include the
Culm inher of Spray Down—making a total distance of about
17 miles. As the strike is generally east and west, it was hoped
that we should be working in successive horizons, although, in
consequence of the manifold contortions of the beds, this was by no
means certain.

Mention will also be made in the notes of Waddon Barton.
That place is not properly included in this paper, but belongs to.
the one to follow, wherein I hope to work along a line from north
to south.

T have been fortunate in securing the kind assistance of Mr. E.
A. Newell Arber, who has named the plant-remains, and of Mr. G.
C. Crick, who has named the cephalopoda and whose notes are
appended to this paper. The lamellibranchiata and gasteropoda
have not yet been named.

Besides determining the series of fossils obtained by me, Mr. Crick
has carefully examined the material in the Vicary Collection in
the British Museum, and also the few fossils from these beds pre-
served in the Exeter Museum, and thus has allowed me to incorpo-
rate in this short communication everything that is at present
available for study.

The localities are numbered on the accompanying Map (PI.
XXXII) from south-west to north-east.

(1) Canonteign. (Road-cutting.)

Small brachiopoda. Glyphioceras sp.

Posidonomya becheri Bronn (one | Phillipsia cliffordi H. Woodward.
specimen showing the wrinkled
periostracuin),

Vol. 67.| OF SOUTH DEVON; EXETER DISTRICT. 397

(2) Popehouse! Close (surface of a ploughed field on Court Barton Farm
Christow).

Pleurodictyum (2) or Michelinia (2). Glyphioceras spirale (J. Phill.).
Posidonomya becheri Broun. Orthoceras sp.?
Glyphioceras crenistria? (J. Phill.). Phillipsia cliffordi H. Woodward.

(8) Christendown Clump, near Doddiscombsleigh.

Cherts containing radiolaria of very large size. First found by
Mr. C. Davies Sherborn.’

(4) Down Lane, Doddiscombsleigh. (Hedge-section.)

Stroboceras sulcatum (J. de C. Sow.),

Seminula ambiqua ? (J. de C. Sow.).
fragment.

Posidonomya becheri Broun.
Glyphioceras, probably the adult stage
ot Gl. reticulatum. |

| All the fossils from this locality were kindly named for me by Dr. Wheelton
Hind, F.R.C.S., in February 1907. ]
(5) Woodah, Doddiscombsleigh,

Small brachiopod. Glyphioceras spirale (J. Phillips).
Posidonomya becheri Bronn. Re-| Phillipsia cliffordi (?) H. Woodward.
corded by Mr. W. A. EH. Ussher.’

(6) Willhayes Copse. (Hedge-section half a mile west of Dunchideock.)
Glyphioceras sp. ? Young of Glyphioceras reticulatum (J. Phill.).

(7) Bottom of Idestone Hill, and bottom of Ashlake Road.
Glyphioceras beyrichianum (de Kon.) Glyphioceras striolatum (J. Phill.).
var. ? Mariopteris (2) sp.
Glyphioceras reticulatum? (J. Phill.). |
(8) Perridge Tunnel.
Encrinite stems.
Glyphioceras crenistria [recorded by
Mr. Ussher (op. cit. p. 15)].
(9) Perridge (Pateshill Copse).

Urnatopteris cf. tenella (Brongn.).
Neuropteris sp.

Glyphioceras cf. reticulatwm (J. Phill.).
Orthoceras sp. (found by Mr. A. S.
Horne).

Alethopteris sp.
Sphenopteris obtusiloba (?) Brongn.

(10) Pocombe Read-ecutting.

Glyphioceras reticulatum (J. Phill.), | Glyphioceras beyrichianum (de Kon.).
Glyphioceras striolatum (J. Phill.). |

The first two specimens are in the Exeter Museum.
_ (11) Lane near Barley House, Exeter (opposite the entrance to a
field in which a landslip occurred, 1904).
Glyphioceras striolatwm ? (J. Phill.).
(12) Bonhay Road, Exeter.
Dimorphoceras (/ discrepans T. Brown).

Glyphioceras (probably striolatum
J. Phill.).

Lhe two last-named specimens form part of the Vicary Bequest to the
British Museum.

Glyphioceras erenistria (J. Phill.).
Glyphioceras sphericum (W. Martin).

' Misprinted ‘ Gopehouse’ in the map, Pl, XXXII.
* Proc. Zool. Soc. 1908 (2) p. 433.
* «The Geology of the Country around Exeter’ Mem. Geol. Surv. 1902, p. 9.

398 MR. F. G. COLLINS ON THE CULM =«—(s—(tésésT AAC gs. QE,

(13) Stoke Road (roadside section below Stoke Wood).

Glyphioceras reticulatum (J. Phill.). | Glyphioceras inconstans (J. Phill.).

(14) Mincing Lake. (Stream-section.)
Glyphioceras reticulatum (J. Phill.). Glyphioceras davisi Foord & Crick.
Glyphioceras (probably striolatum Small lamellibranchiata.

J. Phill.).

My friend Mr. Lewis James found an impression of Glyphioceras in a hedge-
section a short distance north of Mincing-Lake Bridge.

(15) Chaingate Lane, Pinhoe.

Newropteris sp. "| Urnatopteris ef. tenella (Brongn.).
(16) Messrs. Saunders’s Brickfield, Pinhoe.

Pterinopecten papyraceus (J. Sow.). Glyphioceras beyrichianum (de Kon. .

Euomphalus sp. var. biplexr Haug.

Small gasteropods. Glyphioceras phillipsi Foord & Crick.

Dimorphoceras (?discrepansT. Brown). | Glyphioceras striolatum (J. Phill.).

Glyphioceras reticulatum (J. Phill.). Orthoceras koninckianum @ Orbigny.

Glyphioceras davist Foord & Crick. Orthoceras obtusum T. Brown.

Glyphioceras beyrichianum (de Kon.), | Orthoceras sp. «.
var. crenatum Haug.

(17) North of Westwood Church. (Hedge-section.)

Odontopteris (?) sp. Neuropteris (Cyclopteris) sp.
Neuropteris schlehani Stur. leuropteris sp.

(18) Clyst Hydon, (Hedge-section.)
Neuropteris schichani (2) Stur. _ Lepidodendron, part of a leaf-base.
Neuropteris cf. heterophylla Brongn. | Bothrodendron (?) sp.
Mariopteris (2) sp. | Trigonocarpus (2) sp.
Sphenopteris sp. | Sigillaria sp. (decorticated).
Alethopteris sp. _ Stigmaria sp.

Calamites (?) sp.

VY. Report on THE PLAnt-REMAINS,

Mr. Arbev’s report on the plant-remains is as follows :—

‘8th March, 1910.

‘IT have now completed an examination of the specimens which you sent last
week. The collection is very typical of the best possible specimens that one
can get from the Culm Measures. I fully understand that this collection
represents much hard work, and I am quite certain from the evidence in North-
West Devon that, imperfect and fragmentary as they are, your specimens
represent as good examples as it will ever be possible to get from these beds.
At the same time they are so fragmentary that it is almost impossible: to
determine them. A Newropteris, or possibly two, appear to be common, and in
one case the species appears to be clearly N. schlehani, Stur, which I have
already described from Devon. Another fern-like plant may be Urnatopteris
tenella (Brongn.), though one cannot becertain. Several Calamites occur, but I
cannot determine the species. The small scars shown on certain specimens are
very puzzling: I am inclined to regard them as isolated root-scars of Stig-
maria. If so, they show how much these plants were drifted and broken before
incrustation took place. These fossils might also conceivably be small branch-
sears of a Calamite, but I do not think this likely. These specimens are
obviously of Upper Carboniferous age, but they are not sufficiently numerous
to indicate the horizon..... I think that you have got better specimens than
any hitherto obtained from the neighbcurhood of Exeter... Your specimens
leave nothing to wish for in preservation, but they are too fragmentary to be
determined.

‘T remain, yours truly,
EK. A. Newer ARBEr.,

Vol. 67.| OF SOULTH DEVON: EXETER DISTRICT. 399

In 1902 Mr. Arber * suggested that it would be well

‘if possible, to drop the term Culm Measures altogether in speak ng of
the Devon Carboniferous rocks, and to apply the nomenclature adopted with
regard to other British areas of similar age.’

I venture to hope that the present paper brings such a change one
step nearer.

A series of the specimens referred to in this paper will be placed
in the British and in the Exeter Museums.

My warmest thanks are due to Mr. Arber and to Mr. Crick, both
of whom have spent much time and taken infinite trouble over my
often fragmentary material. I am also indebted for kind assistance
to Mr. J. Allen Howe, Dr. Hind, Mr. F. R. Rowley, Curator of the
Exeter Museum ; and to Mr. T. H. Withers, who kindly named the
trilobites,

To Mr. W. P. Studholme I am indebted for kind permission to
work at Fordlands, and to Messrs. Saunders for allowing me to
collect at the Pinhoe Brickfields. Last, but not least, I must
thank Mr. C. Davies Sherborn, who has been with me over the
ground deseribed in this paper, and who not only suggested the
work but has helped me at every turn.

VI. Norss on CarpontFerous CepHatopops from the NrI@HBOUR-
00D of Exrrmr.” By Gzoree C. Crick, Assoc.R.S.M., F.G.S.

The following notes refer chiefly to specimens which have been
collected by Mr. F. G. Collins. A few of the fossils examined are
in the Exeter Museum, while some, which formed part of the
Vicary Bequest, are in the British Museum. The specimens gene-
‘rally are not well preserved, and the Ammonoids but rarely exhibit
the suture-lines.°

DiMoRPHOCERAS (? DISCREPANS Brown, sp.).

1849. Goniatites discrepans T. Brown, ‘ Illustrations of the Fossil Conchology
of Great Britain & Ireland’ p. 28 & pl. xxi, figs. 8 & 15.4

The genus Dimorphoceras appears to be represented by a much
compressed, poorly-preservyed, imperfect specimen, about 10 mm.
in diameter, exposed on the surface of a piece of a nodule from
Pinhoe. About half of the outer whorl seems to have belonged
to the body-chamber ; the rest of the outer whorl is septate, and
near the umbilicus exhibits portions of several septa, but these are
too incomplete for the definite determination of the species. The

fossil is possibly referable to Dimorphoceras discrepans (Brown).
Two specimens in the Exeter Museum, labelled ‘ Exeter’ and

1 ‘The Fossil Flora of the Culm Measures of North-West Devon, &c.’
Phil. Trans. Roy. Soc. ser. B, vol. exevii (1905) p. 320.

* Communicated by permission of the Trustees of the British Museum.

* In the following notes a record of the complete distribution of each species
is not attempted.

+ For references and synonymy, see A H. Foord & G. C. Crick, Catal. Foss.
Ceph. Brit. Mus. pt. 3 (1897) p. 222.

400 MR. G.C. CRICK ON CARBONIFEROUS CEPHALOPoDA | Aug. 1911,

numbered 4541, seem to belong to this species ; they are associated
with several examples of what appears to be Glyphioceras strio-
latum.

The species has been recorded from the Vale of Todmorden, High
Green Wood, and Hebden Bridge (Yorkshire),’ as well as from the
marine bands i in the Coal Measures of Lancashire.’

Localities.—Pinhoe brickfield*; and ‘ Exeter [Exeter Mus.]|.’

GLYPHIOCERAS BEYRICHIANUM (de Koninck).

1843. Goniatites beyrichianus L. G. de Koninck in J. J. @Omalius d’Halloy,
‘Précis élémentaire de Géologie’ p. 515.

1897. Glyphioceras diadema (H. E. Beyrich); A. H. Foord & G. C. Crick,
Catal. Foss. Ceph. Brit. Mus. pt. 3 (1897) p. 202 (in part).

1898. Glyphioceras beyr ichianwm (L. G. de Koninck); EH.) Haug, ‘ Etudes sur
les Goniatites’ Mém. Soc. Géol. France, Paléont. vol. vil, no. 18, p. 95
& pl. 1, figs. 1-21, 23.

The species usually recorded from England under the name of
Glyphioceras diadema includes, according to Prof. Haug, Gl. bey-
richianum (L. G. de Koninck) with several varieties, and Gi.
striolatum (J. Phillips).*

Var. biplex Haug.—Pinhoe brickfield has yielded several examples
of this variety, with diameters ranging from about 55 mm. to
21 mm., the umbilicus of the largest being about 10 mm. wide. This
variety is also represented doubtfully from the ‘ bottom of Idestone
all

Var. crenatum Haug.—Some small, widely-umbilicated, internal
casts from Pinhoe, having a diameter of about 5 mm., closely
resemble this variety of Prof. Haug, but their umbilical margins
are smooth. They may be widely-umbilicated young examples of
Glyphioceras striolatum.

Var. coronatum Haug.—This variety may be represented by a
poor example from Pocombe.

Glyphioceras diadema has been recorded from the Pendleside
Series, and indicated as passing up into the Millstone Grits and
Lower Coal-Measures.’ It has also been recorded from the Lower
Coal-Measures of Lancashire,® and from South Wales.’

Localities.—Var. biplev: Pinhoe brickfield, and possibly also
from the ‘bottom of Idestone Hill’; var. crenatum: probably from
Pinhoe brickfield ; var. coronatum: possibly from Pocombe.

1 A. H. Foord & G. C. Crick, Catal. Foss. Ceph. Brit. Mus. pt. 3 (1897),
pp. 222-23. Dr. A. S. Woodward has told the present writer that the
specimens C 5293, there recorded as from ‘ Halifax,’ were really from Hebden
Bridge.

2 W. Hind, Q. J. G. 8. vol. 1xi (1905) p. 544.

3* Unless otherwise stated, the specimens are at present in the collection of
Mr. F. G. Collins.

4 J. Phillips, ‘Geol. Yorks.’ pt. 2 (1886) p. 234 & pl. xix, figs. 14-19.

5 W. Hind & J. A. Howe, Q. J. G. 8. vol. lvii (1901) App. B, table facing

p- 402.

° H. Bolton, Trans. Manchester Geol. Soc. vol. xxviii (1904-1905) p. 413.

7 W. Hind, Geol. Mag. dec. 5, vol. i (1904) p. 585.

Vol. 67.| FROM THE NEIGHBOURHOOD OF EXETER. 401

GLYPHIOCERAS STRIOLATUM (J. Phillips).

1836. Goniatites striolatus J. Phillips, ‘Geol. Yorks.’ pt. 2, p. 234 & pl. xix,
1897. Gian diadema (H. E. Beyrich); A. H. Foord & G. C. Crick,
Catal. Foss. Ceph. Brit. Mus. pt. 3, p. 202 (in part), with fig. 98.

1898. Glyphioceras striolatum (J. Phillips); EK. Haug, ‘Etudes sur les

Goniatites’ Mém. Soc. Géol. France, Paléont. vol. vii, no. 18, p. 92 &
pl. i, figs. 22, 24-27.

This appears to be the most commonly occurring species at
Pinhoe. ‘To it are referred numerous examples, usually ranging
in diameter up to 12 or 13 mm., while some display the fine sculpture
exceedingly well. A nodule from this locality contains a specimen,
about 19 mm. in diameter, possessing the fine sculpture of the
species enclosed within another whorl, which is crushed and appa-
rently quite smooth, having a diameter of a little more than 40 mm.
Another nodule from the same locality exhibits a similar example,
also showing the finely-sculptured inner whorl at a diameter of
about 20 mm. surrounded by a portion of the crushed outer whorl
of rather more than 40 mm. in diameter; the ornaments exhibit a
prominent crest on the outer portion of the lateral area and a deep
sinus on the periphery ; the umbilicus appears to have been rela-
tively small, infundibuliform, and with a rounded margin. Another
example in the British Museum from Pinhoe [C 9122 a], 8 mm. in
diameter, is referred to this species.

A crushed example and counterpart, labelled as from ‘near Barley
(opposite entrance to field in which landslip occurred), seems to be
referable to this species. Its transverse strize are but slightly
waved, not so much as in Glyphioceras reticulatune.

An imperfect impression from the ‘bottom of Ashlake Road’
probably belongs to this species, and possibly also a specimen from
the ‘bottom of Idestone Hill.’ It is also doubtfully represented
at Mincing Lake.

The impression of a portion of a whorl about 35 mm. high, in a
piece of black shale from Perridge Tunnel, displays a sculpture
similar to that of the large outer whorls already mentioned from
Pinhoe. Transverse ornaments are very conspicuous, but there
are no traces of any longitudinal lines; near the peripheral margin
of the lateral area the shell possessed a distinct groove as in Gi,
bilingue, but the shell-ornaments do not agree with those of that
species, and resemble quite closely the sculpture of the large
examples from Chokier (Belgium), figured as Glyphioceras diadema
by Foord & Crick, and subsequently referred by Prof. Haug (op.
supra cit. pp. 92 & 94) to GI. striolatum (J. Phillips).

Several small specimens in the Exeter Museum, labelled ‘ Exeter’
|No. 4541], appear to belong to this species; also an example,
10 mm. in diameter, in the same Museum, labelled ‘Dunsford Road,
above Pocombe Bridge.’

Phillips’s striolatus has been regarded as a synonym of Beyrich’s

' Op. cit. figs. 98 a & 98 b, p. 203.

402 MR. G. C, CRICK ON CARBONIFEROUS CEPHALOPoDA | Aug. I9II,

diadema,* but Prof. Haug considers these species distinct, and for
the latter adopts L. G. de Koninck’s name beyrichianum.*

The localities given by Phillips ° for this species are :—‘ In shale,
Kulkeagh ; near Enniskillen; in shale, High-Green Wood, near
Todmorden.’

Localities.—Pinhoe brickfield, near Exeter [F. G. C. & Brit.
Mus.]; near Barley ; Exeter [Exeter Mus.]; Dunsford Road, above
Pocombe Bridge [Exeter Mus.]; probably from the ‘bottom of
Ashlake Road,’ Mincing Lake, and Perridge Tunnel; possibly also
from the ‘bottom of Idestone Hill’; and Bonhay Road.

GLYPAIOCERAS RETICULATUM (J. Phillips).

1836. Goniatites reticulatus J. Phillips, ‘ Geol. Yorks.’ pt. 2, p. 235 & pl. xix,
figs. 26-32; G. gibsoni J. Phillips, ibid. p. 236 & pl. xx, figs. 13-18.
1897. Glyphioceras reticulatum A. H. Foord & G. C. Crick, Catal. Foss. Ceph.
Brit. Mus. pt. 3, p. 193 (with references & synonyms).*
1898. Glyphioceras reticulatum Kh. Haug, ‘ Etudes sur les Goniatites” Mém.
poe ee France, Paléont. vol. vii, no. 18, p. 87 & pl. i, figs. 32-39,
The specimens from Pinhoe here referred to this species are
relatively thicker than the Yorkshire forms. A well-preserved and
apparently uncrushed example, 31 mm. in diameter, is 17 mm.
thick, and has an umbilicus about 8°3 mm. wide at its margin,
while the height of the outer whorl is about 14 mm. _ Portions of
the test are beautifully preserved, and show both the prominent
transverse and some very faint longitudinal strie. The jugosum-
stage of the species is also represented. The British Museum col-
lection contains several fairly well-preserved examples from the
Vicary collection, labelled ‘ Pinhoe.’’®
The best-preserved of these [C 9118] is elliptical, its diameters
being 35 and 24 mm. respectively. Its constrictions are less curved
than is usual in Gl. reticulatum, and in this respect the fossil
approximates to Gil. excavatum’; but the type-specimen of that
species—a specimen with the whole of the outer whorl non-septate
and apparently belonging to the body-chamber—is a more com-
pressed shell than ordinary examples of GJ. reticulatum. Moreover,
if one of the specimens, a completely septate example 20 mm. in
diameter in the Gilbertson Collection, is correctly identified as
Gl. excavatum, the lateral lobe of the suture-line of that species
is, as described by Phillips, more acute than in G1. reticulatum ;

1 A. H. Foord & G. C. Crick, op. cit. p. 202.

> E. Haug, op. cit. pp. 92 & 95. See also ante, p. 400.

3 “Geol. Yorks.’ pt. 2 (1836) p. 234.

4 See also A. H. Foord, ‘Monograph of the Carboniferous Cephalopoda of
Ireland’ (Pal. Soc.) pt. 5 (1903) p. 182.

> Nos. C 9115-18, C 12662 (young), & C 12800. Probably these are the
fossils mentioned by Mr. W. A. E. Ussher, ‘Geology of the Country around
Exeter’ Mem. Geol. Surv. 1902, p. 16.

6 Goniatites excavatus J. Phillips, ‘ Geol. Yorks.’ pt. 2 (1886) p. 235 & pl. xix,
figs. 33-35. Not Goniatites excavatus J. Phillips, ‘Paleoz. Koss. Cornwall,
Devon, & W. Somerset’ 1841, p. 121 & pl. 1, fig. 282 = Meneceras molarium
(G. F. Whidborne).

Vol. 67.] FROM THE NEIGHBOURHOOD OF EXETER. 403

but unfortunately the suture-lines are not visible in the specimens
from Devon. An examination of a number of examples of the
two species leads me to endorse Phillips’s statement that the two
species are closely allied, if not the same.

With this species is identified a well-preserved example, 19 mm.
in diameter, in the Exeter Museum, labelled ‘Dunsford Road,
above Pocombe Bridge.’

Imperfect impressions of shells and quite young specimens from
the ‘bottom of Ashlake Road’ and a young shell from Willhayes
Copse probably belong to this species, which we have also recognized
from ‘ Mincing Lake.’

The British Museum collection includes from the Vicary Bequest
two examples from Newton St. Cyres, 4 miles north of Exeter, that
belong to this species. They are 18-5 and 13-5 mm. in diameter
respectively, the smaller one having a still smaller example (4 mm.
in diameter) attached to it.

To this species is also referred an example from ‘ under Stoke
Wood,’ measuring rather more than 20 mm. in diameter, exhibiting
the sculpture of the test. Embedded in the same piece of matrix is
a Specimen apparently referable to Glyphioceras inconstans.

Dr. Hind records the species from Doddiscombleigh (South

Devon),' and states that
‘this species occurs at certain horizons in the Pendleside Series, in practically
every locality in the Midlands where these beds occur.’
He also records it from the marine band beneath the Gin-Mine
Coal at Nettlebank (North Staffordshire)? It has moreover been
recorded from the- Lower Coal-Measures of Lancashire*® and from
South Wales.*

Localities.—Pinhoe brickfield, near Exeter [F. G. C. & Brit.
Mus.]; Dunsford Road, above Pocombe Bridge; bottom of Ashlake
Road ; Mincing Lake; Newton St. Cyres [ Brit. Mus.]; ‘under Stoke
Wood’; and Willhayes Copse.

GLYPHIOCERAS DAvist Foord & Crick.

1897. Glyphioceras davisi A. H. Foord & G. C. Crick, Catal. Foss. Ceph. Brit.
Mus. pt. 3, p. 198, figs. 95 a-95 ec. 5

1898. Glyphioceras reticulatum, var. davisi FE. Haug, ‘ Etudes sur les
Goniatites ’ Mém. Soc. Géol. France, Paléont. vol. vii, no. 18, p. 90.

This species is represented from Mincing Lake by a portion of
the outer whorl, with the included part of the penultimate whorl of
a rather large example. The inner whorls are wanting.

The portion of the penultimate whorl consists of about a third
of a volution, is sublanceolate in cross-section, being at its mid-
length about 24 mm. high and 21 mm. thick at its prominent
rounded umbilical margin. The outer third of the whorl is pinched

' «The Naturalist’ 1909, p. 170.

2 Q. J. G. 8. vol. lxi (1905) p. 538.

* H. Bolton, Trans. Manchester Geol. Soc. vol. xxviii (1904) p. 413.

+ A. Strahan, &c. ‘The Geology of the South Wales Coalfield, pt. viii—Th e
Country around Swansea’ Mem. Geol. Sury. 1907, p. 25.

404 MR. G. C. CRICK ON CARBONIFEROUS CEPHALOPODA [ Aug. I9II,

together, producing a strong rounded ridge along the middle of the
lateral area. There are traces of the suture-lines.

The fragment of the outer whorl comprises about an eighth
of a volution, increasing near the umbilical margin to nearly a
quarter of a volution. It is sublanceolate in cross-section, 48 mm.
high, and about 38 mm. wide at the umbilical margin. It shows
the faint strongly-curved growth-lines and the prominent umbilical
margin of the species, but the ridge on the middle of the lateral
area is here almost obsolete. Since this portion reveals no traces
of the suture-lines, it seems to have formed part of the body-
chamber.

This imperfect example indicates a fossil larger than the type-
specimen, for in the latter with a diameter of 60 mm. the outer
whorl was only 27 mm. high.

Prof. Haug ae supra cit.) regards the species as either a senile
form or a variety of Glyphioceras reticulatum.

The type-specimen was obtained from the late James W. Davis,
of Halifax, and is recorded as being from that locality; but
Dr. Smith Woodward told the present writer that the collection of
fossils of which it formed a part really came from Hebden Bridge.

Dr. Hind & Mr. Howe record the species from the Pendleside
Series of the Midlands, and indicate that it passes upwards into the
Grits and the Lower Coal-Measures.’

Locality.—Mincing Lake.’

GLYPHIOCERAS INconsTANS (J. Phillips).

1841. Goniatites inconstans J. Phillips, ‘ Paleoz. Foss. Cormwall, Devon, &
West Somerset’ p. 123 & pl. hi, figs. 238 a—238 e.

A distorted example in the Exeter Museum | No. 6834], of which
the locality is unrecorded, seems to be referable to this species, but
the main ribs in passing from the edge of the umbilicus are more
forwardly-inclined than they are represented to be in Phillips's
figures ; the ornaments form a distinct orad-concave curve on the
periphery.

This species greatly resembles young forms of Glyphioceras
reteculatum. a species to which it evidently is closely allied, for,
according to Phillips, it passed through a series of forms parallel
to those described by him in regard to Gil. reticulatwm, with which
species he at first believed it to be identical ; but, compared with
that species, he pointed out (op. ct. p. 124) that
‘the umbilicus is here larger, the ridges on the inner edge of the whorls are
continued into the cavity, and the back [periphery] is in all cones oe
ages broader, and in the young state more cariniform in the middle.’

Embedded in a piece of shale from ‘under Stoke Wood,’ and
containing a specimen here referred to Gl. reticulutum, there is

1 Q. J. G.S. vol. lvii (1901) App. B, table facing p. 402.
2 [Since the paper was read Mr. Collins has found in the Pinhoe brickfield a
much better example of this species, showing the beautifully-ornamented test.—
G. C. C., August 5th, 1911.]

Vol. 67.| FROM THE NEIGHBOURHOOD OF EXETER. 405

a distorted specimen (now elliptical in outline), the diameters of
which are 19 mm. and 12°5 mm. respectively, that seems to belong
to this species.

The only locality given by Phillips (loc. cit.) for this species is
‘near Exeter (Mr. Drury’s cabinet),’ and this is the sole species
from the neighbourhood of Exeter mentioned by him.

Localities. — ‘Under Stoke Wood’; locality unrecorded
[Exeter Mus. No. 6834].

GLYPHIOCERAS PurtirpsI Foord & Crick.
1836. Goniatites obtusus (pars) J. Phillips, ‘ Geol. Yorks.’ pt.2, p. 234 & pl. xix,
fig. 12 (non figs. 10, 11 & 13 = Glyphioceras ohtusum).
1897. Glyphioceras phillipsi A. H. Foord & G. C. Crick, Catal. Foss. Ceph.
Brit. Mus. pt. 3, p. 172.

Of the five examples from Pinhoe here referred to this species,
two, from the collection of the late Mr. William Vicary, are in the
British Museum Collection [C 9120 & C 9121]. These specimens,
43 mm. and 35 mm. in diameter respectively, exhibit the shell-
ornament, and are entirely septate, so that the shell must have
attained considerable dimensions. The type measures 32 mm. in
diameter, but a completely septate example in the British Museum
collection [C 5300] from Hebden Bridge is 36 mm. in diameter.

Of the examples in Mr. Collins’s collection, one, displayed in
counterpart in a broken nodule, is 23 mm. in diameter, and
exhibits a considerable portion of the test, but no traces of the
suture-lines; the others are portions of crushed internal casts,
entirely devoid of the test, but exhibit the character of the sculpture,
indicating shells which measured at least 33 and 60 mm. in
diameter respectively.

A well-preserved example in the Exeter Museum, 12°6 mm. in
diameter and exhibiting the ornaments of the test, is also referred
to this species. It is labelled ‘Stoke Road, Exeter, just beyond
Cowley Bridge (in pebble).’

The locality of the type-specimen is unrecorded, but the species
was identified by its authors from High-Green Wood and Hebden
Bridge.’ It has also been recorded from the Pendleside Series of
the following localities :—Coldcoates*; Crimsworth Dean, Horse-
bridge Clough, near Todmorden’; and at Foynes Island (Co.
Limerick) *; also from the marine band beneath the Gin-Mine Coal
at Nettlebank (North Staffordshire).? Dr. Hind states that it has
never been found in the Carboniferous Limestone Series.”

Localities.—Pinhoe brickfield, near Exeter [F.G. C. & Brit.
Mus.]; Stoke Road, Exeter, just beyond Cowley Bridge (in pebble)
| Exeter Mus. ].

? Dr. Smith Woodward tells me that the collection which included the speci-
mens, recorded in the original description of the species as from Halifax,

really came from Hebden Bridge. They were obtained from the late James W.
Davis, of Halifax.

2 W. Hind, Q. J. G. S. vol. lxi (1905) p. 538.
° W. Hind & J. A. Howe, ibid. vol. lvii (1901) App. B, table facing p. 402.

406 MR. G. C. CRICK ON CAKBONIFEROUS CEPHALOPODA | Aug. I9gIT,

GLYPHIOCERAS SPHZRICUM (Martin).
1809. Conchyliolithus Nautilites sphericus W. Martin, ‘ Petrifacta Derbiensia’
p. 15 & pl. vu, figs. 3-5.
1814. Ammonites sphericus J. Sowerby, ‘Min. Conch.’ vol. i, p. 116 & pl. liii,
fig. 2 [B.M. No. 48871).

A fairly well-preserved pyritized specimen in the British Museum,
obtained with the Vicary Bequest and labelled ‘ Bonhay Road,
Exeter,’ is referred to this species. Its measurements are :—
diameter, 18-+ mm.; greatest thickness, 15 mm.; height of outer
whorl, 7 mm.; ditto above preceding whorl, 4 mm.; width of
umbilicus, 4mm. The suture-line is well shown, and agrees with
that of the specimen figured by Sowerby, which may also have been
Martin’s type. This is probably one of the specimens mentioned
by Mr. Ussher as being in the Vicary collection.” .

In a ‘decomposed blackish ferruginous rock’ exposed in the
valley between Five-Mile Hill Cross and Ball Oaks, between
Tedborn St. Mary, Whitestone, and Holcombe Burnell, Mr. Ussher
records the occurrence of badly-preserved goniatites, ‘suggesting
the presence of Glyphioceras sphericum.’’ Dr. Hind records the
species from the ‘ black shales and limestones’ at Venn, in North
Devon; and notes* its presence in South Devon in the cherty
representatives of the Codden-Hill or Prolecanites-compressus Beds.
It has also been recorded in a pyritized condition from Fremington
(North Devon).’ :

In the Midlands, Dr. Hind & Mr. Howe have identified the
species from the Carboniferous Limestone of Castleton (Derby-
shire), Park Hill, Cracoe, and Thorpe (Yorkshire), and Clitheroe
(Lancashire) °; while the same authors and Mr. G. W. Lamplugh’
have recorded the species from the Poolvash Limestone (Isle of
Man).

ea te Road, Exeter [ Brit. Mus. C 9111].

GLYPHIOCERAS CRENISTRIA (J, Phillips).

1836. Goniatites crenistria J. Phillips, ‘ Geol. Yorks.’ pt. 2, p. 234 & pl. xix
figs. 7-9.8

From Popehouse Close, Christow, there is an uncrushed specimen,
consisting of about half a shell, 22 mm. in diameter, 14 mm. thick,
with an umbilicus some 4 mm. wide at its margin; it is orna-
mented with fine crenulated stris, which are direct on the lateral
area and form only an exceedingly shallow orad-concave curve on

1 For references and synonymy, see A. H. Foord & G. C. Crick, Catal. Foss.
Ceph. Brit. Mus. pt. 3 (1897) p. 157; also A. H. Foord, ‘Monogr. Carb. Cephal.
Treland’ (Pal. Soc.) pt. 5 (1903) p. 154.

2 ‘Geology of the Country around Exeter’ Mem. Geol. Surv. 1902, p. 16.

SViGida pao:

: : fhe Naturalist? 1909, pp. 169, 170.

5 Catal. Foss. Ceph. Brit. Mus. pt. 3 (1897) p. 160.

6 Q. J. G.S. vol. lvii (1901) App. A, table facing p. 402.

7 * Geology of the Isle of Man’ Mem. Geol. Surv. 1903, p. 262.

8 For references and synonymy, see A. H. Foord & G. C. Crick, Catal. Foss.
Ceph. Brit. Mus. pt. 3 (1897) p. 160 ; and A, H. Foord, ‘Monogr. Carb. Cephal.
Ireland’ (Pal. Soc.) pt. 5 (1903) p. 157.

Vol. 67.1] FROM THE NEIGHBOURHOOD OF EXETER. 407

the periphery ; it exhibits a single faint constriction, but no suture-
lines, and therefore apparently formed part of the body-chamber.
It is doubtfully referred to this species.

From Bonhay Road, Exeter, and forming part of the Vicary
Bequest, the British Museum collection includes a somewhat dis-
torted pyritized internal cast, 28 mm. in diameter, 17-5 mm. thick,
with an umbilicus 3°5 mm. wide, having the septal sutures and
shell-ornament characteristic of this species.

The locality of the type-specimen is ‘ Bolland,’ the other localities
for the species given by its author being Queen’s County, Ferma-
nagh, and the Isle of Man.. Phillips* subsequently recorded the
species from Swimbridge and Venn in North Devon, and from
Trescot in South Devon. Dr. Wheelton Hind also records it from
the black shales and limestones at Venn.?

Mr. Ussher * records the occurrence of this species in a ‘ dark-
grey hard mudstone’ at Perridge Tunnel, but the only example
submitted to the writer from this locality does not exhibit the
characteristic sculpture of the species. It is here referred to
Glyphioceras striolatum.

Dr. W. Hind & Mr. J. A. Howe record this species from the
Carboniferous Limestone of Yorkshire and Derbyshire*; while
from the Poolvash Limestone (Isle of Man) the species has been
recorded both by the same authors and by Mr. G. W. Lamplugh.’

Localities.—Bonhay Road, Exeter [ Brit. Mus. C 1908]; possibly
also from Popehouse Close, Christow.

GLYPHIOCERAS SPIRALE (J. Phillips).

1841. Goniatites spiralis J. Phillips, ‘Paleoz. Foss. Cornwall, Devon, & West
Somerset’ p. 121 & pl. 1, fig. 233.6

This species is well represented from Waddon Barton, in the
collections both of Mr. Collins and of the British Museum, by the
ordinary crushed examples exhibiting the strong longitudinal orna-
ments and the periodical constrictions. Mr. Collins’s collection also
includes a beautifully-preserved example from Popehouse Close,
Christow.

Besides Waddon Barton in South Devon, the species occurs at
Bampton,’ Hele ° and Venn?’ in North Devon, being, as Mr. Ussher

‘ Palzeoz. Foss. Cornwall, Devon, & West Somerset’ 1841, pp. 121, 122.
‘The Naturalist’ 1909, p. 169.

‘Geology of the Country around Exeter’ Mem. Geol. Surv. 1902, p. 15.
Q. J. G. S. vol. lvii (1901) App. A, table facing p. 402.

‘Geology of the Isle of Man’ Mem. Geol. Surv. 1903, p. 262.

° For references and synonymy see A. H. Foord & G. C. Crick, Catal. Foss.
Ceph. Brit. Mus. pt. 3 (1897) p. 210; and A. H. Foord, ‘ Monogr. Carb. Ceph.
Treland’ (Pal. Soc.) pt. 5 (1903) p. 19].

7 J. Phillips, ‘ Pal. Moss. Cornwall, Devon, & West Somerset’ 1841, p. 121;
A. H. Foord & G. C. Crick, Catal. Foss. Ceph. Brit. Mus. pt. 3 (1897) p. 211;
and W. A. E. Ussher, ‘The Geology of the Quantock Hills, &c.’ Mem. Geol.
Surv. 1908, p. 35.

8 A. H. Foord & G. C. Crick, op. cit. p. 211.

° W. Hind & J. A. Howe, Q. J. G. S. vol. lvii (1901) App. B, table facing
p. 402; and W. Hind, ‘ The Naturalist’ 1909, p. 169.

o - wo NY

408 MR. G.C. CRICK ON CARBONIFEROUS CEPHALOPODA [Aug. 1911,

states (op. cit. p. 35),

‘a common fossil in the upper beds of the Lower Culm (Posidonomya Beds). . -
both in the northern and southern outcrops.’

Dr. Hind & Mr. Howe zecord the species from the Pendleside
Group at Pendle Hill; it has also been recorded from Congleton

?

Edge (Cheshire),* and from South Wales.*

Localities.—Waddon Barton* [F. G. C. & Brit. Mus.]; Pope-
house Close, Christow ; Woodah.

? Nomismocrras sprrorsis (J. Phillips).
1836. Oe aati spirorbis J. Phillips, ‘ Geol. Yorks.’ pt. 2, p. 237 & pl. xx,
1841. iid ue J. Phillips, ‘ Paleoz. Foss. Cornwall, Devon, & West
Somerset’ p. 122 & pl. li, fig. 236.°
This species appears to be represented by an impression on the
surface of a small slab, labelled ‘ Waddon Barton,’ which does
not exhibit any example of Glyphioceras spirale, the form most
commonly occurring at this locality. Phillips’s type-specimen came
from Black Hall, Bolland,’ and he recorded the species also from
Westleigh in North Devon.’ Dr. Hind & Mr. Howe record the
species from the Pendleside Group at Black Hall, Bolland, and
from near Todmorden; also from the Venn and Swimbridge Culm
Shales of North Devon.® It has been recorded from Codden Hill,
near Barnstaple,’ and doubtfully from Waddon Barton,*° near Chud-
leigh (South Devon).
Locality.—Waddon Barton,” near Chudleigh (South Devon).

PROLECANITES (?) sp.

The British Museum collection contains from Pinhoe the impres-
sion (in part of a nodule) of one side of a slowly-increasing shell,
elliptical in outline, its diameters being about 45 and 30 mm.
respectively, the corresponding measurements of the umbilicus being
25 and 15 mm. respectively. ‘The whorls seem to have been
rather compressed, the margin of the periphery subangular, the
umbilicus wide and its walls step-shaped, the umbilical zone of the
whorl fairly well defined, relatively narrow and convex. ‘The test
appears to have been ornamented with extremely faint striz; these

l Op. supra cit. vol. lvii (1901) App. B, table facing p. 402.
2 'W. Gibson & W. Hind, Q. J. G.S. vol. lv (1899) p. 554.
3 A. Strahan, &. ‘The Geology of the South Wales Coalfield, pt. viii—The
Country around Swansea’ Mem. Geol. Surv. 1907, p. 25.
4 This locality is not properly included in the present paper.
5 For references and synonymy see A. H. Foord & G. C. Crick, Catal. Foss.
Ceph. Brit. Mus. pt. 3 (1897) p. 213.
6 ‘Geol. Yorks.’ loc. cit. 7 ¢Paleoz. Foss. &e.’ p. 128.
8 Q. J. G. S. vol. lvii (1901) App. B, table facing p. 402.
9 Ibid. vol. li (1895) p. 653.
10 A. H. Foord & G. C. Crick, Catal. Foss. Ceph. Brit. Mus. pt. 3 (1897)
. 215.
11 This locality is not properly included in the present paper.

Vol. 67. ] FROM THE NEIGHBOURHOOD OF EXETER. _ 409

are sigmoidal and forwardly-directed on the lateral area, making a
feeble orad-concave curve on the inner portion and a feeble orad-
convex curve on the outer part of the whorl, and are suddenly
deflected backwards at the peripheral margin where the test is
raised into obscure folds. The form of the shell and the nature of
its ornaments suggest the genus Prolecanites; but, as there are no
traces of the septa, its reference to this genus is somewhat doubtful.
Locality.—Pinhoe brickfield, near Exeter.

ORTHOCERAS KONINCKIANUM d’Orbigny.

1844. Orthoceras anceps L. G. de Koninck, ‘ Descr. des Anim. Foss. Terr.
Carb. Belg.’ p. 517 & pl. xlv, figs. 7 a-7 6 (non Minster).
1850. Orthoceratites koninekianus @Orbigny, ‘ Prod. de Paléont.’ vol. i, p. 113.
1888. Orthoccras koninckianum @VOrbigny ; A. H. Foord, Catal. Foss. Ceph.
Brit. Mus. pt. i, p. 119.

This species is represented by an example from Pinhoe, almost
completely embedded in a portion of a nodule, which also contains
besides other fossils an example of the species referred to in these
notes as Glyphioceras striolatum. Only a length of about 10 mm. of
the shell is visible, but this is sufficient to show a couple of its
characteristically-shaped annulations and the fine transverse raised
lines of the test. The specimen is subcircular in transverse section,
its diameters being 20 and 18 mm. respectively.

The British Museum collection contains an example from
Hebden Bridge (Yorkshire) [C 5272]. Through the kindness of
Dr. Wheelton Hind, the writer has also had an opportunity of
examining a small block from Foynes Island (County Limerick)
containing an example of this species associated with adult and
immature forms of both Glyphioceras reticulatum and Gl. strio-
latum, as well as a Dimorphoceras (probably discrepans Brown),
and innumerable small calyciform goniatites exhibiting the proto-
conch. In fact, this assemblage reminds one very much of the
assemblage occurring in the nodules from Pinhoe. According to
Dr. Wheelton Hind,* these beds at Foynes Island contain a fauna
characteristic of the Pendleside Series. Dr. Hind & Mr. Howe’
record this species from the Pendleside Group at Crimsworth Dean,
Horsebridge Clough, near Todmorden (Yorkshire).

Locality.—Pinhoe brickfield, near Exeter.

Orruoceras optusum T. Brown.
1841. Orthocera obtusa T. Brown, Trans. Manchester Geol. Soc. vol. i (1841)
p. 219 & pl. vii, fig. 36.

One of the most interesting cephalopods from Pinhoe is an
example of this species, consisting like the type-specimen (with a
cast of which I have compared it) of the posterior portion of the
body-chamber, the posterior surface being apparently an impression
of the anterior surface of the last septum. The specimen is

1 ‘Monogr. Brit. Carb. Lamell.’ (Pal. Soc.) vol. ii, pt. 3 (1904) p. 173.
2 Q. J. G.S. vol. lvii (1901) App. B, table facing p. 402.

Q23.G.5. No. 267. 2F

|
)
:

410 MR. G. C. CRICK ON CARBONIFEROUS CEPHALOPODA [Aug. IQII,

conoidal and depressed, 49 mm. long, with an elliptical cross-
section, of which the diameters at the anterior end measure 35 and
25 mm. respectively. The siphuncle, seen at the posterior end of
the specimen, is at about a third of the shorter diameter from
the surface. The fossil tapers rather rapidly, the sides being
apparently continuous with the basal surface. The test is rather
thick, ornamented with slightly waved, somewhat irregular,
upwardly-imbricating lines, which are very close together (three or
four in the space of 1 mm.) on the posterior part of the specimen,
their distance apart gradually increasing to about 1°5 mm. on the
anterior part of the fossil.

The type-specimen came from High-Green Wood, near Hebden
Bridge (Yorkshire), and is preserved in the Manchester Museum.
Through the kindness of Dr. Wheelton Hind, the writer has had an
opportunity of examining avery similar specimen from the Pendle-
side Series of Hebden Bridge. Mr. Bolton records it from the Lower
Coal-Measures of Lancashire.’ |

Locality.—Pinhoe brickfield, near Exeter.

ORTHOCERAS Sp. a.

A small fragment from the Pinhoe brickfield seems to belong to
this genus. It is exposed in counterpart on the split surfaces of
part of a nodule, on one surface being displayed the internal cast
of the shell, and on the other the inner side of the test; but the
boundaries of the shell are not shown. The shell is slightly curved,
and ornamented with regular transverse, rounded, equidistant
ridges. The fragment, which is 21 mm. long and about 13 mm.
wide at its widest part, bears fourteen ridges, the two last, probably
the hindermost, being much narrower than the rest. Although the
surface of the test cannot be seen, judging from its internal aspect
the ridges appear to have been rounded and neither forwardly-
imbricating as in Orthoceras obtusum, which occurs at the same
place, nor so fine as the ornamentation of the specimen from Pope
house Close, near Christow, mentioned below.

Locality.—Pinhoe brickfield, near Exeter.

ORTHOCERAS sp. (2.

Another species is represented by a flattened fragment, preserved
in counterpart on the split surfaces of a small slab from Popehouse
Close, near Christow. The fossil is about 28 mm. long, 15 mm.
and 11:5 mm. wide at the anterior and posterior ends respectively,
and ornamented with very fine, transverse, raised lines, which are
much finer than those of the example from Pinhoe, five of them
occupying a space of 2 mm.

Locality.—Popehouse Close, near Christow.

1 Trans. Manchester Geol. Soe. vol. xxviii, pt. 14 (1904) p. 413.

\

Vol. 67.] FROM THEA NEIGHBOURHOOD OF EXETER. co

The cephalopoda, therefore, identified from the Carboniferous
rocks in the neighbourhood of Exeter, are :—

AMMONOIDEA, Glyphioceras spirale.

Gl. striolatum.

? Nomismoceras spirorbis.
Prolecanites (/) sp.

Dimorphoceras (? discrepans).
Glyphioceras beyrichianum.
Gl. crenistria.

Gl. davisi.

Gl. inconstans. BERN ola es
Gl. phillipsi. Orthoceras koninckianumn.
Gl. reticulatum. O. obtusuin.

Gl. sphericum., O. sp. a and O. sp. B.

From the ‘ Pendleside Group’ Dr. Hind & Mr. Howe’ record
the following cephalopoda :—

.
AMMONOIDEA, Glyphioceras vesica.
Nomismoceras spirorbis.
Prolecanites convpressus,
Pr, serpentinus.

Dimorphoceras gilbertsont.
D. looneyi.

Gastrioceras carbonarium.

G. listeri.

Glyphioceras bilingue. RU TOTO
Gl. davisi. Ephippioceras clitellarium.
Gl. diadema. Orthoceras aciculare.

Gl. implicatum. O. koninckianuim.

Gl. nitidum. O. steinhauert.

Gl. phillipst. O. sulcatum.

Gl. reticulatum. Temnocheilus carbonarius,
Gl. spirale. T. conecavus,

Gl. stenolobum.

and from the underlying Carboniferous Limestone * :—

AMMONOIDEA. | NAvriLoIpEA.
Glyphioceras crenistria, Actinoceras breynit,
Gl. mutabile. | A. gigantewm.

Celonautilus subsulcatus.
Discites discus.

Gl. sphericum.
Gl. striatum.

Gl. truncatum. D, planotergatus.
Nomismoceras rotiforme. D, sulcatus.

N. vittigerum. Phacoceras oxystomus,
Prolecanites compressus. Solenocheilus cyclostoma.
Pronorites cyclolobus. S. dorsalis.

Stroboceras bisuleatum.
Temnocheilus coronatus.
Thrinoceras hyattt.

Comparing the list of South Devon forms with that of the fauna
of the ‘ Pendleside Series ’ and that of the Carboniferous Limestone
as tabulated above, we cannot fail to be impressed with the great
resemblance of this fauna to that of the ‘ Pendleside Series,’ a
resemblance which is emphasized by the occurrence of such forms
as Glyphioceras reticulatum, Gl. davist, Gl. beyrichianum, aud Gi.
striolatum (the two last-named having been usually recorded as

1 Q. J. G. S. vol. lvii (1901) App. B, table facing p. 402.
? Ibid. App. A, table facing p. 402.
Z2F2

°

412 MR. G. C. CRICK ON CARBONIFEKOUS CEPHALOPODA [ Aug. IQII,

Gl. diadema), Orthoceras koninchianum and O. obtusum*; though it
should be mentioned that all these forms, excepting O. konincki-
anum, have been recorded either as occurring in the Lower Coal-
Measures or as passing up into the grits and Lower Coal-Measures.

The two forms which seem to indicate a somewhat lower horizon

than the ‘ Pendleside Group’ are Glyphioceras cremstria and Gi.
sphericum, species characterizing the Carboniferous Limestone.
These, as already said, are stated to have been found at Bonhay
Road (Vicary), and it is to observed that their mode of preserva-
tion differs from that of the rest of the fossils in that they are
pyritized, more or less uncompressed, and exhibit the suture-
lines.

Respecting the ‘ Pendleside Series,’ which in the Midlands is
stated to consist of about 1000 feet of black shales, resting on the
top of the massif of Carboniferous Limestone, Dr. Hind states that °

‘The Pendleside Series thins out rapidly to the south of Derbyshire, and is
only represented by a few feet in Leicestershire and Shropshire. Still further
south, I consider that the Bishopton Beds in South Wales and the Lower Culm
Series of Devonshire are the homotaxial equivalents of the Pendleside Series
of the Midlands. The lithological similarity of the series in Devonshire, and
especially the peculiar fauna of the Lower Culm, agree so markedly with the
characters of the Pendleside Series that one cannot be blind to the evidence.

Moreover, the Lower Culm is overlaid by grit beds, which are in turn over-
laid by soft shales with bullions at Instow containing :—

Pterinopecten papyraceus. l Gastrioceras carbonarium.
Posidoniella levis. Dimorphoceras gilbertsont.
Gastrioceras listeri. Orthoceras sp.

a fauna which is abundant in the Lower Coal-Measures of Lancashire and the
Midlands ; and at Robert’s Quarry, near Bideford, immediately above beds
containing a fairly rich and typical Coal-Measure flora, is a band of fawn-
coloured, iron-stained shale with Carbonicola acuta, a characteristic shell of
the middle portion of the Coal-Measures, so that one may safely infer that the
Culm-Measures of Devonshire represent the Carboniferous sequence of the
Midlands, mznuws the massif of Carboniferous Limestone.’

During the visit of the Geologists’ Association to North Devon at
Easter 1910, Dr. Wheelton Hind gave a lecture on the correlation
of the Carboniferous rocks in North Devon with those in other
areas. The report’ of the lecture states that the species which
Dr. Hind regards as the most important zonal forms, and, taken
together, form the faunal sequence which characterizes the lower
part of the Upper Carboniferous rocks, are :—

Honme'ot, \GastrZocer as Wester... ccs seeecees ces Sesser Millstone Grit.
35 Gly phoCer Os CUTMGUE = ceeeec ace sccenconses ee Millstone Grit.
i Glyphicceras spirale and Gl. diadema ......
Glyphioceras reticulatum (maximum) ...... . :
» aL a ( m) Pendleside Series.
es Nomismoceras rotiforme and Posidonomya
COGMERG ah. Sa RE ohio CaN a ea atNe

1 This species is not recorded by Dr. Wheelton Hind from the ‘ Pendleside
Series’; but the type-specimen (see antea, p. 410) came from High-Green Wood,
near Hebden Bridge, and we have also seen the species from the ‘ Pendleside
Series’ of Hebden Bridge.

2 ‘Monoer. Brit. Carb. Lamell.’ (Pal. Soc.) vol. ii, pt. 8 (1904) p. 174.

3 Proc. Geol. Assoc. vol. xxi (1910) pp. 463-64.

4 By the list given above (p. 411) it will be seen that both these forms were
included by Dr. Hind & Mr. Howe.in the fauna of the ‘ Pendleside Group.’

Quart. Journ. Geol. Soc. Vol. LXVII, Pl. XXXII.

LL i (|

YP (18)Cly Hydon
il il gall

a7we fs
CULM Bhs
Spraydown,

NN
t i
GEOLOGICAL SKETCH-MAP
of the
BXEETER .
Dis! RiCT
LU a of = sh les.
i 0 4
PE

NEIGHBOURHOOD OF EXETER.
4

*

a

Quart, Journ. Geol. Soc, Vol. LXVIL, Pl. XXXIL

Uy — mT
CULM MEASURES
AS
E Hil * E E\RUE\S iy
Crediton | |
Le cAnPA
LU bo iil <a
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\ J ®)stokce Wood
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C U L M Mincing Lake ({4) ~ Pinhoe Brickfield | | |
Bonhay Road
MEASURES 2
arley@) EXETER
Pateshill Copse NIB R E\D\||'S\ié R LES
:
: er: e
NM, ridg
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Willhayes Copse LEE Ly

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Tyr Wootah GEOLOGICAL SKETCH-MAP
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hee l EXETER
easton DISTRICT

| DARTMOOR: rer par

AT Te ATL CY r| Seale of English Miles.
os x aly Riva ¥Y | 0 I 2 AI 4
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GroLocicaL SketcH-Map or THR NEIGHBOU
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4

.

a ain

Vol. 67.] FROM THE NEIGHBOURHOOD OF EXEZER. 413

These are underlain by the Prolecanites-compressus Beds of the
Cyathaxonia Zone, with which Dr. Hind correlates the Codden-Hill
cherts. The report goes on to say :—

‘These beds [Codden-Hill cherts] are succeeded by black shales and lime-
stones with Posidonomya becheri and some compressed goniatites. Glyphioceras
reticulatum has been obtained by Mr. Inkermann Rogers, and Mr. Hamling
notes the presence of Gl. spirale at Filleigh. The latter species is very plenti-
ful in South Devon, at Waddon Barton. Most of the other fossils have been
found in the south part of the Culm area.

‘At Instow oceur beds characterized by (Gastrioceras lister?, which are
succeeded by a series containing typical Coal-Measure plants and Carbonicola
acuta,

It concludes with the statement :—

‘So in the difficult, much-disturbed county of Devon, all the life-zones of
the Pendleside Series known in the Midlands, with the exception of Glyphio-
ceras bilingue, have been found.’

The last sentence is not quite clear, because, according to
Dr. Hind & Mr. Howe, the ‘ Pendleside Series’ occurs between the
Carboniferous Limestone Series and the Millstone Grit, and in
the list of zones above cited the ‘ zone of Glyphioceras bilingue’ is
referred to the Millstone Grit.

Again, in the second paragraph above quoted, after referring to
the plentiful occurrence of GI. spirale at Waddon Barton in South
Devon, the report states: ‘ Most of the other fossils have been
found in the south part of the Culm area,’ It is not clear to
which fossils allusion is here made, and reference to the literature
containing such records is not given.

The fossils, however, described in the present note, support for
South Devon what Dr. Hind has stated to be the case in North
Devon, namely, that the Lower Culm-Measures are the homotaxial
equivalents of the ‘ Pendleside Series’ of the Midlands.’

EXPLANATION OF PLATE XXXII.

Geological sketch-map of the neighbourhood of Exeter, on the scale of 3 miles
to the inch. [or ‘ Gopehouse Close’ read ‘ Popehouse Close.’ |

Discussion.

Dr. T. F. Sisty noticed that while the plant-remains collected
in this area were referred by Mr. Newell Arber to the Upper
Carboniferous, the molluscan fauna definitely indicated, on the
other hand, a Lower Carboniferous horizon, namely, the Pendleside
Series, underlying the level of the ‘ plant-break’ in the Midland
succession. He asked the Author whether the mollusca and the
plants had been found in different localities.

Mr. Dewry remarked that, at Codden Hill and elsewhere in North
Devon, Prolecanites compressus occurred in beds of radiolarian chert,
which were overlain at Venn and Swimbridge by shales and lime-

1 It may be mentioned that quite recently the ‘ Pendleside Series’ has been
discussed by Dr. Balduin Nebe in his work oy the Culm fauna of Hagen in
Westphalia (Neues Jahrb. Beilage-Bd. xxxi, pt. 2, 1911, pp. 487 e¢ seqq.).

414 THE CULM OF SOUTH DEVON: EXETER DisTRicT. [Aug. 1911,

stones containing Posidonomya becheri and other fossils constituting
the fauna of the Pendleside Series. But in North Cornwall and
the area west and east of Dartmoor, an apparently different order of
deposition was found among the beds. Along the coast near
Boscastle the Upper Devonian slates underlay carbonaceous shales,
and these were succeeded by grits with occasional flows of lava,
while the radiolarian cherts were not met with for a distance of
some 3 miles farther north, and then 90 feet of them formed the
headland known as Firebeacon Point. Eastwards, this order was
continued as far as Dartmoor, and near Launceston limestones
were seen dipping beneath radiolarian cherts. These limestones
contain Posidonomya becheri; but no fossils had been found in
the cherts. It was, however, difficult to believe that the massive
cherts which formed a nearly continuous outcrop for 20 miles were
not on the same horizon as the beds at Codden Hill. If this were
so, the position of the Codden-Hill Beds with regard to the lime-
stone beds in North Cornwall differed from their position in North
Devon.
_ But it must be remembered that overthrusting had reversed the
normal succession over wide areas in NorthCornwall. At Tintagel
this had affected the Upper Devonian sequence, while at Holne on
the Dart, south-east of Dartmcor, the Upper Devonian was thrust
upon the Culm beds. It did not, therefore, seem improbable that
overthrusting might have brought about the apparent difference
in the succession in North Cornwall.

The Avrnor, in reply to Dr. Sibly, said that the bulk of the
plants sent to Mr. Arber came from the north of the area, but
broken plant-remains occurred throughout the series.

a Oe ted ae

Mal. 67] THE LLANDOVERY ROCKS OF MONTIGOMERYSHIRE. 415

15. The Luanpovery and Associatep Roexs of Norru- HasTern
Monreomerysuire.' By Artur Wans, B.Sc., F.G.S. (Read
April 26th, 1911.)

[PLrates XXXITI-XXXVI_.|

ConrTENTs.
Page
Te; Wentropiciommme ae tic oak ols cies steel be daucdechonesees 08 GAS
EUS, Bitte ee a eee tao ps ttre saa ok po haie vela nde oo ses dae hamedaie ane es 415
LT. Siraibimea paneer GT. © 2. .wponeisse dene cdtonpansar leant sa 418
LV: The Stratigraphical Succession: 1c... 02.200 sts. .ceeee bese sedan 418
V. Detailed Description of the Subdivisions ..................... 422
V ho Sreme pir eeeanm erate io. 2.6 cots Masked inn tinad deve sd doemsisane anys soe 442
V Ei @oreciamoman (Me Sima g . 6c...) ldaiade tens anne poke cociese doen 444
VIII. Igneous Rocks—The Welshpool Dyke ........................ 446
IX. Notes on the Palzontology of the Area .....................4.. 449

I. Inrropuction.

Tae district investigated is one which was well loved by
Murchison, who paid many visits, about the year 1836, to Powis
Castle while preparing his great work on the ‘ Silurian System.’

It extends for a distance of over 7 miles in a north-easterly
direction from a point a mile or so south of Welshpool in Mont-
gomeryshire, and includes a tract of country embracing the Vale of
Guilsfield, and a portion of the valley of the Severn. It is bounded
on the west by the watershed of the Vyrnwy, the area covering
nearly 40 square miles. The country may be broadly described as
consisting of three parallel ridges of Silurian rocks running in a
north-north-easterly direction, with two wide intervening valleys
containing subsidiary though usually more precipitous ridges, formed
by the escarpments of rocks of Ordovician age. It was among
these fertile valleys and finely wooded hills that De Quincy found
solace during part of his early wanderings.

II, Hisrortcat Review.

Murchison, in 1839, was the first to give any account of the
structure of this region. Speaking of the whole of the country
between the Breiddens and the Berwyns, he describes [1]” the
Silurian strata as lying

‘in undulations or troughs ........ constituting a number of parallel
anticlinal and synclinal lines.’ (Ch. xxiv, pp. 300 ez seqq.)

' Thesis approved for the Degree of Doctor in Science in the University of
London.
+ Numerals in square brackets refer to the Bibliography (§ III) on p. 418,

416 MR. A. WADE ON THE LLANDOVERY AND [ Aug. 191,

Of the particular district with which I now propose to deal he
has much to say. He describes very fully the Welshpool Dyke,
and notes its apparent effect upon the strike of the neighbouring
rocks, which is generally north-north-east and south-south-west, the
direction of the axis of the dyke. One very interesting passage
is worthy of quotation: referring to the ridges in the Upper
Park of Powis Castle, he says (op. cit. p. 290) :-—

‘The dislocation in the higher ridge of the Upper Park changes its
direction to east-north-east and west-south-west, according with that of the
Breidden Hills, and it is therefore possible that the dyke of Welshpool and
the lines of disturbance immediately proceeding from it, are only slight aber-
rations from a line of eruption of which the Breiddens was the chief focus ;
it is, however, to be observed that the disturbed line of Welshpool is parallel
to the strike of the volcanic ridges of Corndon, whilst the Breidden Hills....
cut through the stratified deposits in a direction which diverges 45° from those
parallels.’

In dealing with the stratigraphical succession of the area, he
recognizes two divisions only :—

(1) An Upper Silurian division, consisting chiefly of dull grey shales con-
taining occasional spherical concretions which be compares with the septaria
of the London Clay. Owing to the absence of limestone-bands, he makes no
attempt to differentiate between the Wenlock and the Ludlow.

(2) A Lower Silurian division, which he calls Caradoc Sandstone and
Llandeilo Flags. It consists of impure sandy limestones in the upper beds.
with conglomerates, hard grits, and mottled red-and-grey shales beneath. He
describes sections at Powis Castle, Moel-y-garth, and the Gaerfawr, the first
of which he illustrates by means of a diagram. With regard to the latter
section he says (op. cit. p. 306) :— :

‘This red conglomerate, overlying the whole system of the grey sand-
stones of the Gaerfawr, proves that the similar red conglomerate and gritty
beds of Welshpool, Powis Castle, the Quakers’ Burial Ground, and other
places which rise from beneath the overlying mudstones or Upper Silurian
rocks, form the upper strata of the Caradoc Sandstone or Lower Silurian
rocks.’

It is now possible to differentiate between the Wenlock and the
Ludlow ; and it can also be shown that, instead of forming the upper
strata of the Caradoc Sandstone, the Red Conglomerate Series lies
unconformably upen them. It is, therefore, necessary to remove a
part of the Conglomerate and associated beds from Murchison’s
Lower Silurian, and to establish a Llandovery group in the area.

In 1850 a geological map of the district, executed by W. T.
Aveline & H. W. Bristow, with A.C. Ramsay as Local Director,
was published by the Geological Survey, together with a section.
For purposes of mapping, Murchison’s grouping of the rocks was
adopted. Wide areas are mapped as Wenlock Shale, which in
reality are occupied by Ludlow Beds. The dividing-line between
Upper and Lower Silurian is drawn at the base of the upper shale-
beds, so that part of the Llandovery is mapped along with the
Wenlock, while the lower portion is mapped with the Upper
Ordovician strata.

In 1866, ‘The Geology of North Wales’ was published by the

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 417

Geological Survey. In it, Sir Andrew Ramsay mentions the dis-
turbed state of the Wenlock Shales in this area, and notes the
absence of the grit-beds at the base. With regard to the apparent
conformity between the Upper and the Lower Silurian strata in
Montgomeryshire, he says that

‘it doubtless arises from the circumstance that during the deposition of the
Upper Silurian rocks, the lower strata of this particular area had been but
slightly disturbed.’ [8] p. 207.

It will be seen later that this unconformity is greater than he
anticipated. In the appendix on the fossils, J. W. Salter noted many
specimens from the neighbourhood, as did also Robert Etheridge,
in the enlarged edition published in 1881.

No further work appears to have been done in this district, until
J. Bickerton Morgan began his investigations somewhere about
the year 1884. In 1890, an abstract of his results was published
[5]. He recognized the true age of the Red Conglomerate beds,
and stated that they transgress upon ‘ different zones of the under-
lying Ordovician rocks.’ ‘The overlying shales, sandstenes, and
mudstones, he considered to be of Lower Wenlock age.

About the same time, he wrote two papers dealing with the
geology of this part of Montgomeryshire, for the ‘ Montgomeryshire
Collections’ [6]. Here, he gave a somewhat fuller account of the
different beds occurring in the district, and stated that the Bala
Limestone with associated phosphatic beds occurs in Gwern-y-brain.
A short list of fossils was also given, to prove the age of the Red
Conglomerate beds. His conclusions were, in the main, correct,

- although some of the shales, considered by him to be of Wenlock age,

must be regarded as belonging to the Upper Llandovery.

Morgan stated his intention to map the base of the Silurian in the
area, but his labours were unfortunately cut short by his death.

In connexion with Morgan’s work the late Prof. T. Rupert Jones
[8], in 1890, dealt with the Ostracoda from the black shales of
Gwern-y-brain. He described several new species, and showed the
close affinity of these fossils with North American types.

In the years 1885 and 1890, Prof. Watts [4] & [7] dealt with
the petrology and geology of the Breiddens and the Long Mountain.
In the latter paper, he detailed a sequence with graptolite zones
from the top of the Bala Beds to the Upper Ludlow. He noted the
fact that the Llandovery grits and limestones lie unconformably
upon the lower beds, and described a dyke of diabase thrust up

. along the junction at Cefn, near Buttington.

Further work on the petrology of the neighbourhood was done by
Mr. Jevons [11] in 1904. He opined that certain of the ‘diabases ’
described by Prof. Watts in the Breidden area are keratophyres.

In a further paper in 1905, Prof. Watts [12], after determining
the age of these rocks to be probably post-Llandovery, welcomed the
suggestion that they may be keratophyres, since it would bring about
a tendency to unify the type of Ordovician and post-Ordovician
intrusive rocks of different areas.

418

MR. A. WADE ON THE LLANDOVERY AND [Aug. 1911

The work done by Miss Elles and Miss Wood [9] & [10] in 1900
in the Wenlock and Ludlow beds of the neighbouring Long Moun-
tain district is now classical.

[1] 1889.

[2] 1854.
[3] 1866.

[4] 1885.

[5] 1890.

[6] 1885

& 1891.
[7] 1890.

[8] 1890.

[9] 1900.

IIT. Srraticgraraican Lireratvure.

Sir Ropertox I. Murcuison, ‘The Silurian System’ Chaps. xxiii &
XXxlv.

Sir Ropericx I. Murcmison, ‘ Siluria’ 1st ed.; 1872, 5th ed.

Sir Anprew C. Ramsay, ‘The Geology of North Wales’ Ist ed.,
Mem. Geol. Surv. vol. iii; 1881, 2nd ed.

W. W. Warts, ‘On the Igneous & Associated Rocks of the
Breidden Hills in East Montgomeryshire & West Shropshire ’
Q. J. G.S. vol. xli, p. 532.

J. Bickerton Morean, ‘On the Strata forming the Base of the
Silurian in North-East Montgomeryshire’ Rep. Brit. Assoc.
(Leeds) p. 816.

J. Bickerton Moraan, ‘ Montgomeryshire Collections’ vol. xviii,
p. 149 & vol. xxv, p. 359.

W.W. Warts, ‘ The Geology of the Long Mountain, on the Welsh
Borders.’ Rep. Brit. Assoc. (Leeds) p. 817.

T. Rurerr Jonzs, ‘On some Paleozoic Ostracoda from North
America, Wales, & Ireland’ Q. J. G. 8. vol. xlvi, p. 1.

Miss G. L. Euxss, ‘The Zonal Classification of the Wenlock Shales
of the Welsh Borderland’ Q. J. G. S. vol. lvi, p. 370.

[10] 1900, Miss E. M. R. Woop [Mrs. Suaxrspnar], ‘The Lower Ludlow
Formation & its Graptolite Fauna’ Q. J. G. §. vol. lvi, p. 415.

[11] 1904. H.S. Jrvons, ‘Note on the Keratophyres of the Breidden &
Berwyn Hills’ Geol. Mag. dec. 5, vol. i, p. 13.

[12] 1905. W. W. Warts, ‘On the Igneous Rocks of the Welsh Border’ Proce.
Geo]. Assoc. vol. xix, p. 1738.

IV. Tue SrraTigRaPHICAL SUCCESSION.
Before dealing in detail with the stratigraphical succession, I

think it well to tabulate the full sequence obtained as a result of
my investigations over the whole area. ‘This is owing to the fact
that a complete sequence cannot be established by any single
section, in consequence partly of the overlapping of certain of the
higher series, and partly (in all probability) of the thinning-out of
beds in the area. The district is one of transition, and in many of
its characters constitutes a connecting-link between neighbonring
areas on every side. This feature has made it necessary to dis-
tinguish between a western facies and an eastern facies in certain
cases.

The different group-names have been chosen to indicate places
where the beds are best exposed and, as a rule, most fossiliferous.

Vol. 67.| ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 419

a 3. Sandy flags and shales, some-
times calcareous.
Ludlow. Yr Allt Gr 2. Hard thick flags, with thin
| 800 feet + ; mou: Bere ca and septarian
nodules.
| 1. Thin muddy shales.
SALOPIAN, oie
Ne Blue flags, gritty, with cal-
2 a ot be ; careous ‘concretions’ or
Wenlock. | acies. poulders. f
200 feet. Blue flags, as a rule minutely
| A. Eastern false - bedded, with - earthy
L facies. mudstones and a thin lime-
L stone-bed.
pa pe ce be srk Barren shales, green and
300 feet. : purple.
( B. Western
facies | 2. Thick calcareous flags and
(Cloddiau < mudstones.
U Group) | 1. Blue shales.
VALENTIAN. pper | 250 feet.
Llandovery 4
700 feet. 9
| : A. Eastern G
facies Z Thick calcareous flags, with
| (Cefn Group) Pentamerus Limestone.
etsoree
Lower Powis-Castle (Red sandstones and conglome-
Llandovery. Group. rates, with occasional develop-
100 feet. ments of limestone.
Black shivery phosphatic shales,
B with a band of black crystal-
SSHGILUIAN | Gwern-y-brain Group. line limestone near the
50 feet. base (=Staurocephalus Lime-
stone ?).

( (3. Hard calcareous mudstones

and limestones (=Lower

Bala Limestone) with coarse

ashy felspathic bands;

Gaerfawr Group. thin phosphatic ashy shales
CARADOCIAN, J 1000 feet. 4

1300 feet.

at the base.
2. Massive grits, with bastard
limestones.
i 1. Flags and grits, with some
© shale-bands.

1000 feet ?

| Pwll-y-glo Group. Shales and flags, with some grit-
L 300 feet. bands.
GLENKILN-
HartTFELL : : : : 2. Nodular mudstones and gre
(=piguensres) Trilobite-Dingle Group. shales. ae

SHALES). 1. Splintery grey shales.

Fig. 1.—Section from Penbryn Dingle to Trefnant Dingle, on the scale of 6 inches to the mile.

Section across Moel-y-garth.
(Section I, fig. 1.)

The succession can be best established
by a brief description of the two most
typical sections in the area. A fairly
complete succession may be obtained by
starting at the foot of the dingle by
Penbryn Farm and working in a south-
westerly direction towards Cloddiau,
Ty-brith, and Trefnant. It will after-
wards be necessary to deal with each
subdivision in detail.

Cloddiau Beds.
a = 'Trilobite-Dingle Shales.

d!

Trilobite-Dingle Shales.—The
stream by Penbryn Farm has cut a
narrow gorge in a mass of dark-grey
splintery shales, The weathered surfaces
are usually stained reddish-brown or:
yellow. The upper beds near the road
that crosses the top of the dingle consist
of more massive mudstones, which pre-
sent a nodular appearance when broken.
About 800 feet of these beds are here
exposed.

Pwll-y-glo Group.

b

Pwll-y-glo Group.—As we pass
along the road to the south-west, shales
and mudstones soon give way to beds
which differ, in that they are banded
with flags as well as with occasional
seams of grit. They can be traced in
the road, and are exposed in an old
quarry on the south side of it: about
300 feet of these strata are passed here.
This group is intermediate in character
between the underlying shales and the
overlying grits.

Wenlock Shales with limestone-nodules.

Gaerfawr Grits.

Cloddiau
C
c

Gaerfawr Group.—On our right
we now face the fine tree-covered ridge
of Moel-y-garth, which is an escarpment
formed by the outcrop of hard massive
grits. These grits are now seen crossing

= the road: they are in thick beds, with
8 some shaly parting below and sandy
eS flags above. Between 700 and 800 feet

of these beds are passed over—the full
sequence not being shown, owing to the
overlapping of a massive red conglo-
merate.

Powis-Castle Conglomerate.

f = Yr Allt Beds (Lower Ludlow Shales).

d

Powis-Castle Group.—This con-
glomerate crosses the road about 150

ree

Vol. 67.| THE LLANDOVERY ROCKS OF MONTGOMERYSHIRE. +21

yards from the tiny village of Cloddiau. There is no direct
evidence here, either of overlap or of unconformity: these will
become evident when we trace the group into other parts of the area
mapped. Just east of the road the conglomerate is cut off sharply
by a small fault, but it comes in again on the south. The con-
glomerate is followed by red sandstones and flags, which in turn
give place to mudstones.

Cloddiau Group.—These beds, which are soft pale-grey mud-
stones, breaking readily with an uneven splintery fracture, are well
seen on the right-hand side of the road, passing to the north-west
through Cloddiau. They are over 200 feet thick.

Wenlock Shales.—As we pass along the stream towards Ty-
brith Farm, a second gap in the succession is seen to occur; but
immediately under the farm are blue flaggy beds of Wenlock age.
Farther up the southern branch of the stream, the beds contain big
limestone-boulders yielding Wenlock or Upper Llandovery fossils.

Yr Allt Group.—H we follow the branch which runs westwards
in the direction of Trefnant, we see that the blue flaggy beds soon
give place to a great series of thin buff-coloured shales, which
become more sandy and flaggy as we proceed towards Trefnant
Farm.

It will be observed that in this succession there are two gaps. The
first is due to overlap by the Powis-Castle Conglomerate, and the
other to drift in the stream-bed at Cloddiau. ‘The latter gap can
be filled in by examining the lane-section at Cloddiau; but the
apparent conformity of the conglomerate to the beds below is mis-
leading, and it will be necessary to consider briefly a second
section.

Confirmatory Section in Gwern-y-brain.
(Section IT, fig. 2, p. 422.)

Starting from Sarn Bridge, about half a mile to the north of

Guilsfield, a road runs off to the left up a long narrow valley known
as Gwern-y-brain, which cuts through the Gaerfawr ridge.

Trilobite-Dingle Shales.—These beds are not well exposed
in Gwern-y-brain, being obscured by drift. Their relation to the
overlying rocks is, however, well shown in the next dingle to the
north by Middle House.

Pwll-y-glo Group.—tThe peculiar splintery shales and flags of
the group are readily recognized in the first exposure in this dingle.
Their thickness corresponds pretty closely with that observed in the
Moel-y-garth section.

Gaerfawr Grits.—A great series of massive grits with shaly
partings towards the base is now exposed. In places these beds are

422 MR. A. WADE ON THE LLANDOVERY AND [Aug. rorl,

richly fossiliferous, and are bastard limestones
similar in all respects to those of the Caradoc
Grits of Hoar Edge. These become more cal-
careous towards the top, where they are well
exposed in two quarries which are now being
worked. Here they are fossiliferous blue-grey
beds—impure lmestones—containing coarse
gritty bands which consist largely of fragments
of volcanic origin. Several small strike-faults
are present in the neighbourhood of the
quarries.’ The whole of the sequence is here
not less than 1000 feet thick.

Gwern-y-brain Group.— Above the
quarries, a series of jet-black beds cross the
stream. A hard bed, forming a little water-
fall, proves to be a band of black crystalline
limestone about 10 feet thick. Above this
comes 50 feet of black shivery shales.

c''=Gwern-y-brain Shales, with limestone-band.

6 =Pwil-y-glo Group.

Powis-Castle Group.—The Red Conglo-
\Y merates and Sandstones cover these beds.
\ Their apparent thickness is misleading, owing
to a series of small rolls.

The Cloddiau Group of mudstones
follows, and these are covered by shales of
Wenlock age, but the succession is here
obscured by drift.

V. DeraineD DescriIPrion oF THE SUBDIVISIONS.

Powis-Castle Conglomerate.

Gaerfawr Grits.

(A) Ordovician Rocks.

(1) Trilobite-Dingle Shales.—These
beds are the lowest exposed in the district
around Welshpool. They are best seen in a
small dingle west of the town, called by
Murchison Trilobite Dingle. At the scuthern
end of the dingle, purple and grey shales are
seen dipping almost due west. These beds
are very fine-grained and well-bedded, and
frequently show the presence of slickensides
and incipient strain-slip cleavage. Occasion-
ally the beds are nodular, and pass into bluish
micaceous and flaggy mudstones. The joints
are usually stained red and orange with iron-
oxide. The beds are much disturbed, owing to the proximity of the
Welshpool Dyke on the west.

fig. 2.—NSection exposed in Gwern-y-brain, on the scale of 6 inches to the mile.
d
G

d' = Cloddiau Beds.
c' = Bala Limestone

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 423

At the head of the dingle, the beds are stained red, and the dip
repeatedly changes; finally, they pass under the Red Conglomerate
of Cherry-tree Bank.

On the western side of the dingle, the shales abut against the
conglomerate which forms the wall of the Welshpool Dyke. The
character of the junction indicates that the shales are cut off on the
west by a fault which throws down the Powis-Castle Conglomerate
and the Welshpool Dyke itself. Towards the east, the beds again
end abruptly against buff-coloured shales which yield Lower Ludlow
graptolites. The junction is best seen at the southern end of the
dingle behind the old Military Depot. Here, evidently, is a great
fault with a downthrow to the east of apparently over 1000 feet.
This fault may be called the Bron-y-Buckley Fault, from
the fact that the wood in which Trilobite Dingle is situated is
known by this name. On the south, shales occur under the
Red Conglomerate of Powis-Castle Park, which are probably the
southern extension of an inlier of Trilobite-Dingle Beds.

On the north, similar beds occur in the ditches by Cefn-sych
Farm, in the dingle below Sale Farm and in Trelydan Dingle.
They strike north-north-eastwards, and are folded into a series of
small anticlines. The strata are jointed at right angles to the
strike, the joint-planes dipping 65° to 70° south-eastwards. Towards
the top of the section in Trelydan Dingle the shales dip in opposite
directions on opposite sides of the stream: on one side up stream.
on the other down stream. ‘This is due to one of a series of faults
which cross the stream here.

Under Trelydan Cottage a great fault throws down a small anti-
cline of Silurian beds, including a limestone-band which contains
fossils of Wenlock age. This fault is the northern continuation of
the Bron-y-Buckley Fault. Farther north, the beds are hidden
under deposits of drift and alluvium. In this area the shales do not
contain the abundance of Trinucleus concentricus which characterizes
those of Trilobite Dingle; this is due to the fact that these strata
represent a slightly lower horizon than is exposed in Trilobite
Dingle. The same graptolitic fauna is obtained from both localities.
On the western side of the valley, the group is again found cropping
out in the fields south of Brookland Hall. The best exposure here
is seen in the dingle by Penbryn.

The upper beds here become massive mudstones, with flagey
bands towards the top. The beds are extremely fossiliferous in
places, and contain lamellibranchs and graptolites in the lower
and more shaly strata, while 7rznucleus characterizes the mudstone
group. The strata are again linked together by the occurrence of
similar graptolites, which become more rare in the upper part of
the group.

On the north they are again well exposed in Gwern Heylin,
where the strike swings round to the west. A fault of unknown
throw occurs just below the lake. This locality yielded practically
no fossils.

424 MR. A. WADE ON THE LLANDOVERY AND (Aug. rg1r,

If we follow the strike westwards as far as Guilsfield Brook,
it brings us up against a river-cliff consisting of the Powis-Castle
Conglomerate series. The whole of the Ordovician succession of
Moel-y-garth ends abruptly against Silurian rocks here in Guilsfield
Brook. Another huge fault, running north-east and south-west,
occupies the bed of the stream. The throw is to the north-west,
and is at least 2000 feet in amount. This fault may be appropriately
named the Moel-y-garth Fault.

On this side of the valley, the Trilobite-Dingle Shales are not
again well exposed until Middle House is reached, half a mile north
ot Guilsfield, where they are seen in the stream-section, although
they must occur under the drift and alluvium covering the valley-
floor. From this point they can be traced by Ceunant Mill to the
northern limit of the map.

It is fairly certain that the lower beds of the Trilobite-Dingle
Group are of Llandeilo age; but there is no sufficient paleontological
or lithological break in the succession to enable us to draw the

line,

| On
| : 28
Ors ue 5
eo | "ep = ) : Ze
List oF Fossils FROM THE 2) 2) a se ees
Aa VAnvenls eS eet
TRILOBITE- DINGLE SHALES. o | @ | 4 |S ol eee
21 | Sa
©) Ses Q |T-m gs | ao
HHA le | Oo |e
Asaphus powisi Murchison ... ‘ee | At 4
Dionide sp. Seen eta Nae metals 7
Trinucleus concentricus Baton .......-. xh Be ae x
| Trinucleus concentricus, var. caractacit “March. al > Ga 4 i xX
#Trinucleus concentricus, aff. var. portlocki Salter. (ee I hee
| Trinucleus concentricus, cf. var. arcuatus Smith .| ... x x
| Trinucleus intermedius, sp. nov.. “eS Giraghe a's 3 da Os SG al Ree een pee Laie
| Trinucleus cf. lloydi Murchison — Seis ayrouie sr oaicinat hott | Vea nn eae eam | ea
| Climacograptus scherenbergi Lapworth KE San ea ee
| Diplograptus (Amplexograptus) pereveavatus ul x<clex x
apw.
D. (Amplexograptus) arctus Elles & Wood ......) 0)... X |... | &X
Diplograptus (Mesograptus) foliaceus Murch. Xo ae
Diplograptus (Orthograptus) truncatus Lapw... tele. ia:
D. (O.) truncatus, var. pawperatus Elles & Wood| ... xX |
D. (O.) pageanus, var. micracanthus EH. & W. ...| X |... |
Bellerophon ( lai nis one: bilobatus Sa les 4 ul
Bellerophon sp. ar c.G arrest LOX |
Cyrtolites parvus ‘Ulrich, var. carinatus nov. sal ats alae ara
Ctenodonta coarctica Phillips .. BEES ge ec ae lees x
\*Ctenodonta lLingualis Phillips .............26.006..000600| oa. | de | XK x |
i Ceenodanta, atigud SOWELDY. cee ucts: 9-1 S+cinsaee| yan oed ee. ple | aa cage
Crenodontaek Levata wall (cance eran se ece oan | Xe
Ctenodonta sp. ss Sot eth OSA e es crete er le AAT elena RAM Ta

* Fossils marked with an asterisk were collected by J. Bickerton Morgan.

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE, 425

(2) Pwll-y-glo Beds.—These are best exposed in the sharp
ridge of Pwll-y-glo, half a mile west of the Welshpool Dyke. They
consist of shales, mudstones, and flags, with some bands of hard
grit. More or less regular alternations occur—consisting of 2 or
3 feet of shale, with seams of hard, greenish, micaceous grit
varying in thickness from 3 to 12 inches. The beds which form
the ridge are folded into an asymmetrical syncline, along an east-
north-easterly and west-south-westerly axis. The most fossi-
liferous exposure is the second old quarry to the south-west of
Pwll-y-glo Farm. About 100 feet of shales and flags are here
exposed.

The beds strike north-eastwards along the ridge towards the
Bron-y-Buckley Fault. Behind Groes-pluen Farm the series is
seen to be folding over towards the north-west, whereas elsewhere
along the ridge the dip is southerly or south-easterly.

On the south-west, the Pwll-y-glo Beds continue towards Y
Frochas, where the strata are somewhat contorted, much jointed,
and to some extent faulted. At Y Frochas, the outcrop turns round
sharply to the north-east again, and can be traced along the
flanks of Harriets Hill to Cloddiau. ‘The valley between Pwll-

-glo and Harriets Hill is cut in the crest of an cee in the
Pwll- y-glo Beds.

Another faulted syncline occurs at Cloddiau, and the strike
swings right round to the north-west, the dip being south-westerly.
A good selection of fossils can be obtained in a quarry on the road-
side between Cloddiau and Penbryn.

This series cau now be traced round the eastern flanks of Moel-y-
garth Hill, until it is cut out by the Moel-y-garth Fault.

North of Guilsfield this group is largely covered by drift.
It begins to crop out again from under the drift at the foot of
Trawscoed Rough, and is again well exposed in Gwern-y-brain
and the eastern foot of Gaerfawr.

The fossils obtained from these beds clearly indicate a very low
position in the Bala Series. Because of the transitional characters
of the beds, I have considered them as a separate group. They
represent a period of change between the deposition of the lower
shales and the shallower-water types above. Their fauna is
somewhat remarkable, since they contain few of the graptolites
so abundant in the shales below; while brachiopods, which swarm
in the beds above, are practically absent. (See List on p. 426.)

(3) Gaerfawr Group.—This constitutes the most important
series of beds in the district. Wherever these beds crop out, they
form sharp tree-covered ridges, usually crested by a crown of pines.
Their escarpments are particularly steep and abrupt, and, since the
strata invariably dip at somewhat high angles, the dip-slope is also
fairly steep. This has probably led to their outcrops being almost
invariably given over to woodland. The highest ridges in the area,
Moel-y-garth and Gaerfawr, are so formed.

Q.J.G.8. No. 267. 26

426 MR. A. WADE ON THE LLANDOVERY AND [Aug. Ig1t,

>< | From lower beds.

» a ege e

DS

| ie
3 £ S| aro
= - |2 a] a 3
| BA) en
List oF Fossits FRom THE Pwit-y-eto Beps| || ¢ || |8'3| 8.8
(see p. 425). =, eg te pe oe
WG ho |= = | as
1 nD . |Srdi|i= oO
=|8| 28/3 ICs/ Pe
= a eS Silaa
a 1o | oie (ee 7
ASA PWS POWUSe NUMTEMISOM een ces eee erences x Ax
Homalonotus bisulcatus Salter ............0.0 cee eee ee. x sah Ki [henge
Illenus cf. bowmanni Salter Paster dakar ates Seertalhaaee <b sscol ieee
WR NUS CAUIST SALLET = mec eee ore cero taeda. eee eee ae). | pack
Wsatcernia primeva TNOmsOnieer.necsscs sect eee ete es] Moose xX eee
| Lrinucleus concentricus WatOn ......... 2.0... .0. 00000. x Ki) SOn ee
| Trinucleus cf. concentricus Eaton . Bore ee Ganime Gell osc | Soc xt
| Trinucleus concentricus, var. caractact Murch. HK | see lesen, | Xe
Trinucleus concentricus, cf. var. portlocki Salter. |. Po) gee
| Trinucleus fimbriatus Murchison .....................| X oe
|| Lrinucleus aff. nicholsoni Reed ...............00006 Ely
Beyrichia (Tetradella) complicata Salter ......... A x
| Climacograptus cf. bicornis Hall ............... x bss
| Diplograptus (Orthograptus) cf. PUGOSUS, var.| X
apiculatus Elles & Wood
x FD. (O.) pageanus, var. micracanthus Elles & Wood ... | X | ... | «..

D. (O.) calearatus, var. vulgatus Lapworth ...... oe |e Te en
Cyathocrinus guinea Phillips .4..........] ©] "ice loge ee
Spheronites sp. .... Sep Oe tre bi siciocie saa: ois tec | OO
Orthoceras vagans Sil rade net ack se a a x
Bellerophon (Oxydiscus) acutus Sowerby ......... x
Carinaropsis acuta Ulrich & Scofield ............... DOS co sly ae
Bellerophon (Protowarthia) cf. pervolutus U.&S.) ... | ... |... | & |...
Bellerophon (Protowarthia) att. nodosus Sow. ...| ... | ... | .. | .. | X

=. ll Anmodontopsis Gulia MCC oy. eee ere ee ese ee XN wih

x || Ctenodonta cf. coarctica Phillips .....................|
Ctenodonta cf. anglica d’Orbigny ....................- ol an eke eee
Ctlenodontact-longa UW ilnich meta cree se: a: ce: se eA eel eee
Vanuxemia sp. .. Pee Galoas Guanes Klas A §
Orthonota aff. amygdalina ‘Sowerby _ Motes, Siasock nee tae x sag
Leptena rhomboidalis Wilck. ...... er elt. Be Beil" <
Orthis (Dalmanella) testudinaria Dalm. fe) Ae bs aX

| Orthis Cae is ica peas Ne eters lp SGT ee

Annelid tubes ......... Pree st s| SC xX i X

* From J. Bickerton Morgan’s Collection.

The Gaerfawr Group, consisting of hard, greenish, micaceous grits
and flags with a few thin shale-partings, occupies the centre of the
syncline which forms the ridge at Pwll-y-glo. Only asmall thickness
of the beds occurs here, the remainder having been removed by denu-
dation. Across the valley, however, they form the wooded ridge of
Harriets Hill, and terminate at a fault on the south at Y Frochas.

The grits cross the road at Cloddiau, and swing round so as to
strike exactly at right angles to their direction in Harriets Hill.
This change in the direction of the strike is very remarkable. It
causes the ridge of Moel-y-garth to cut across the general line of
all the surrounding hills in the district.

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 427

The great difference, besides the lithological distinction, between
these beds and those already dealt with, is the presence of
vast numbers of brachiopods. The lower beds yield very few
species of Orth?s, and such as are found are insignificant forms
but poorly preserved as a rule. The deeper-sea conditions of the
lower and more shaly beds evidently did not favour brachiopod life;
but in this shallower-water type they appear to have flourished
abundantly. Fossils ean be obtained from numerous localities on
Moel-y-garth, the chief locality being an old quarry at the western
end of Moel-y-garth Wood. Good exposures also occur on the
summit of the ridge itself and on its eastern flanks.

The grits of Moel-y-garth are cut off against Guilsfield Brook,
where they form a magnificent fault-scarp. Since the Moel--

y-garth Fault is a dip-fault, the lateral displacement is very
considerable ; and one has to proceed nearly half a mile on the-

northern side of the fault' before the Gaerfawr Beds come in again
at Groes-lWwyd, west of Guilsfield. Here the beds, broken off by
the fault, come in again, forming another well-marked escarpment
bounding the western side of the Guilsfield Valley, and having its

finest development in the Gaerfawr ridge. The series crops out.

from under the Powis-Castle Conglomerate, striking now in the

normal north-easterly direction and dipping usually at an angle of

about 40° north-westwards. As the beds are traced to the north,
it becomes very evident that a higher sequence is exposed than is.
seen in Moel-y-garth, and the unconformity of the overlying con-
glomerate series becomes distinctly noticeable.

An old quarry in the field above Trawscoed Rough gives the best:

exposure of the middle strata of the Gaerfawr Series. About
50 feet of alternating massive grits and bastard-limestone bands are
exposed. he ‘limestones’ are beds of sandy grit crowded with
fossils, chiefly Orthis, of which only hollow easts remain. The
hollows left by the removal of the calcium carbonate are filled as
a rule with soft powdery limonite, which imparts to the rock a
reddish-brown coloration.

In Gwern-y-brain, a complete section exposing about 1000 feet
of grits and flags can be seen. Near the entrance to Gwern-y-brain
by Twll, some faulting is observed, bringing the grits against the
Pwll-y-glo Group. Farther up the valley, the beds roll slightly,
and strike-faults occur: the exact thickness cannot, therefore, be
measured. It seems very likely that it is greater than that men-
tioned above. A series of old quarries line the road up the valley,
exposing hard massive grits. These contain few fossils, except in
the occasional softer bands.

Two quarries, now being worked near the top of the valley,
expose a higher series of the grits than [| have seen elsewhere..
‘he beds become, in fact, limestones, usually bluish in colour,
and frequently impure and muddy. The lowest beds exposed rest.

262

428 ‘THE LLANDOVERY ROCKS OF MONTGOMERYSHIRE. [ Aug. IQITI.

upon a ‘thin stratum of pale ashy shales. About 50 feet of beds are
exposed in the quarry, giving the following section (fig. 3) :—
Fig. 3.—Section near the top of the Gwern-y-brain alley.

Gem! Thickness Lhe lower shale-band is
| inteet phosphatic. The calcareous

| |

mas Heep | beds in the quarry are thick
‘fossiliferous 4 = and massive. They are, as
-mudstone. a 2 :

ee a rule, fine-grained, blue, and

———= hard. kEach thick bed has

L ll a curious structure, and it
‘Hard, ‘blue, cal- ( l |

oe Mk SSS SSS gradually passes upwards into
with | shaly |! or ft fter a band of coarse whitish grit.
ipartings. Each | === ni : droge a
bed is overlain 4 | | | microscopic examination
2 ass aed ee 3 showed that each of these
pathic grit. be i in grit-bands was exceedingly

Se ————————— rich in large angular frag-
‘phatie and ments of remarkably fresh
ashy shales. 12

plagioclase-felspars, along
‘with quartz-grains, sometimes a good deal of mica, and granules
-of fine-grained igneous rocks, of a basaltic or andesitic nature.
‘Some of the igneous fragments are probably ashes. ‘The fresh.
~felspars and the andesitic fragments seem to indicate rapid denuda-
“tion in a neighbouring voleanic area. A faulted monoclinai. fold
vis seen in the eastern corner of the quarry; the throw is about
‘10 feet to the west. A second fault is seen on the west side of
‘tthe quarry, throwing down again to the west; but the amount
would not be measured.

The fossils, which are beautifully preserved, and often filled with
milk-white calcite, correlate these upper beds very closely with the
horizon of the Lower Bala Limestones both of North Wales and of
South Wales, while the presence of ashy grits in them shows their
intermediate character. The group is sharply defined on paleeonto-
logical grounds. (See List on p. 429.)

(4) Gwern-y-brain Group.—This consists of a series of thin,
fine-grained, jet-black shales, which readily splinter to fragments.
Near the base in Gwern-y-brain occurs a band of black crystalline
limestone. These beds are only fossiliferous at certain horizons,
and occur over a limited area. They are seen above the Gaer-
fawr Limestone in Gwern-y-brain, and can be traced thence to
the dingle below Trawscoed Hall. Here the outcrop seems to
be shifted by a small fault; but shales can be traced along a
depression towards Cross Wood, where they are overlapped by
the Powis-Castle Series. The beds are crowded with inarticulate
brachiopods and ostracods at certain horizons. Gasteropods also
are very abundant; while articulate brachiopods, where present,
are characteristically dwarfed.

lying

.

rom unaer

K

—.*

ee

“oO

MT SE Oe

List oF FossiILs FROM THE
GAERFAWR Grits (see p. 428).

_Asaphus cf. powisi Murchison .....................

Asaphus sp. -.. <5

| Asaphus (Isotelus) ee aha i

Calymene blumenbachi Brongniart ...............

| Cybele sp. .......

Homalonotus bisuleatus Salter.....................
Proetus aff. girvanensis Nich. & Eth. ............
Phacops (Chasmops) conicophthalmus ee)

Salt.’
Phacops (Acaste) alifrons Salter ............... '
Phacops (Acaste) apiculatus Salter ............
Remopleur thee spe e ese oe ane si ested Sees
Trinucleus concentricus Eaton.....................
Trinucleus cf. concentricus Eaton ............... |

| . . . |
| Trinucl. concentricus, var. caractaci Murch. .|

|| Bellerophon (Proto warthia) Dickens Sow. |

|| Orthis ( elie pss vespertilio (Sow.) var..

_ Trinucl. concentricus, aff. var. arcuatus Smith
| Trinucleus elongatus Portlock .....................
|| Lrinucleus nicholsont Reed. ....................--0|

Trinucleus sp. .......

Bellerophon (Protowarthia) portlocki, sp.nov.
Cyclonema donaldi, sp. nov. (see p. 453).........

| Helicotoma cf. marginata Ulvich..................
|| Lophospira ct. serrulata Salter ..................

EROS PUTO Sen ee ek cca d nial tss
Tiny indeterminate gasteropod .....................

_ Tentaculites anglicus Salter
| Glyptocrinus basalis M‘Coy

GU PhO CEU Rp ere i Oe edict va a
Cyathocrinus quinquangularis Phillips .........
Monticulipora fibrosa Goldfuss
Montieulipora lens M‘Coy ............... 00000. 04-

Monticulipora (?) ramosa Goldfuss ............ |

| Ptilodietya (Stictoporella) costellata M‘Coy |
| Orthonota (Orthodesma) rigida Sowerby .......
| Ctenodonta lingualis M‘Coy ............... 0000000.)
| Lingula attenuata Sowerby .............00..0c0000
| Lingula ovata M‘Coy.......00... 000... s0csenceecneees

Lingulie ae eee a es,
Leptena rhomboidalis Wilck. ..............0......|
Orthis cf. (Dinorthis) flabellulum Sowerby ...
Orthis calligramma Dalm. ...................06+-+|
Orthis calligramma var. plicata Salter .........
Orthis calligramma var. virgata Sowerby ......
Orthis (Herbertella) vespertilio Sowerby ......

Orthis (Dalmanella) testudinaria Dalm. ......
Orthis (Dalmanella) elegantula Dalm..........
Orthis (Plesiomys) porcata Sowerby |
Orthis (Plesiomys) poreata,var.grandis Portl.
Orthis (Plesiomys) porcata, var. inflata Salt.

Orthis ct. rustica Sow. .........

OTths GRE Eee
Orthis cf. intercostata Portl. .....................
Plectambonites sericea Sow............20.. cee e005.
Plect. sericea, var. rhomboidalis M‘Coy......... /
Plectambonites transversalis Dalm. ...... fey
Platystrophia biforata,var. fissicostata M‘Coy

| Rafinesquina expansa Sowerby ..................
| Strophomena pecten Linn.........................-.

Strophomena grandis Sowerby.....................
Triplecia spiriferoides M‘Coy ....................

Annelid tubes .........

xX:

Me

nn

XXX:

xx:

x: one:

pe ag Se Se Pee

x:

xX

Old quarry above

Trawscoed
Rough.

Gaerfawr Quarry,

xX XK X

& Pe Ie

2 Mee MRK

Gwern-y-brain.

=

ee

Meee RS LK ta Ki RE RO

BS RDA DR Dae, Dee Dea OK Re

mm

x XK X

xX X

Ranging locally

into the over-
lying beds.

se Se xx:

Gr ae eee. e >. Shee e

pe Goaee ee aa

From under-

x |

430 MR. A. WADE ON THE LLANDOVERY AND [ Aug. I91T,

The Gwern-y-brain Series is not more than 50 feet thick, The
limestone-band is only a few feet thick, and is unfortunately
crystalline, yielding no fossils. It appears to correspond, in its
stratigraphical position, with the Stawrocephalus Limestone at the
base of the Ashgillian. The overlying black shales are of the nature
of passage-beds—since they contain T'rinucleus cf. seticornis, asso-
ciated with a peculiar assemblage of graptolites comprising forms
which suggest an horizon, transitional between the Upper Hartfell
and the Lower Birkhill, at which graptolites appear to be generally
scarce and not well known.

The exact relation between these beds and the underlying grits
is obscured by strike-faulting, while the Powis-Castle Conglomerate
quickly overlaps them above, Obviously, it would be incon-
venient to draw the line between the Ordovician and the Silurian
in these shales; and therefore, since the fauna seems to justify
this correlation, I have regarded them as being equivalent to the
Ashgillian of Dr. Marr.

lying beds.

[|e 2
os!
last oF Fos sre pais) PROM ypany
GWEEN-Y-BRAIN Be SUALES.
| Ae |
Calymene blumenbachi Brongn. | | ... Conularia ct. aspersa Lindstroem.

(Ranges into overlying beds.) ||... | *Hecyliomphalus bucklandi Portlock.

*Trinucleus cf. seticornis His. |... | *Heeyliomphalus minor Portlock.
Bollia lata Vanux. & Hall. ||... | *Hecyliomphalus contiguus var. cam-
Ctenobolina ciliata Emmons. | brensis, nov. (see p. 454).
Ctenobolina cf. ciliata Emmons. Wai eee Orbiculoidea perrugata M‘Coy.

* Krausella arcuata Ulrich. ||... | Orbiculoidea cf. perrugata M‘Coy.

*Leperditia nana (?) Joues. || «. | Orbiculoidea cf. crassa Hall.

*Primitia humilis, var.humilior Jones. | X | Lingula attenuata Soweroy.

*Primitia morgani Jones. ||... | Lingula cf. brevis Portlock.

*Primitia mundula, var. cambrica .. | Lingula obtusiformis, sp. nov. (see

Jones. | p. 435).

*Primitia tumidula Ulrich. on Orbicula cf. terminalis Conrad.

*Primitia ct. ulrichi Jones. a Obolella sp.

*Primitiella unicornis Ulrich, et var.| | ...| Orthis hirnantensis M‘Coy.
Melanella hemidiscus, gen.etsp.nov.| |... Orthis sagittifera M‘Coy.

(see p. 451). ... | Orthis intercostata Portlock.
*Corynoides calycularis Nicholson. | X Orthis (Dalmanella) elegantula
*Dendrograptus sp. | Dalm. (Ranges into overlying

Climacograptus sp. beds.)

*Diplograptus (Mesograptus) mod- | | X Orthis cf. valpyana Navidson.

estus, cf. var. parvulus H. Lapw. | X | Plectambonites sericea) Range into

Diplograptus (Orthograptus) trun- Sowerby. i overlying
catus, cf. var. socialis Lapworth. .. | Pl. transversalis Dalm. beds.
Diplograptus sp. i Trematis corona Salter ?

Glyptograptus persculptus Salter. Siphonotreta micula M‘Coy.

|
|

* From J. Bickerton Morgan’s Collection.

It will be noted that out of 42 species only five range upwards
from the beds below; four of these pass upwards also, being forms
notable for their width of range. The fossil list thus strongly
confirms the evidence afforded by the lithological character of
the beds. It is evident that a remarkable change took place
between the periods of shallow-water deposition during which

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 431

the Gaerfawr Grits on the one hand, and the Llandovery con-
glomerates on the other, were laid down.
These beds do not crop out anywhere in the eastern portion

Old quarries.

CSP '
MG ZG

i

Road and fault.

4,—Section reproduced from Murchison’s ‘ Silurian System’ 1839, p. 304.
Castle rock.

ig.

F
Garden terraces.

ea)

of the area, except under the
Pentamerus Limestone at Cefn near
Buttington. A small outcrop of
shales is exposed in the old
quarries near Buttington Station.
Here the strata fail to exhibit the
peculiar character of the (wern-
y-brain Shales, and lack the Jet-
blackness which is so conspicuous
in those beds. They are nearly
vertical, and yielded Climacograptus
latus (Elles & Wood), a graptolite
which is typical of the highest
horizon in the Bala Beds. The
strata rest upon grits, which appear
to belong to the Upper Gaerfawr
Series.

(B) Silurian Rocks.

(1) Powis-Castle Group. —
This important series of massive
conglomerates, grits, and sand-
stones, with calcareous horizons, is
well named after Powis Castle—
since that structure is built of
materials derived from these rocks,
and is founded upon the finest ex-
posure of them in the district.

In Powis Park, the series forms a
sharp but broken anticline, on the
eastern limb of which the Castle is
built. Murchison was under the
impression that these beds were the
highest in his series of Caradoc
Sandstones. I cannot do _ better
than reproduce his section (fig. 4).

The western limb of the section

is indistinctly lettered under the foliage. The beds are [1] loc.

supra cit. :—

‘q, Purplish-brown calcareous grit with many fragments of encrinites in
beds, from 8 inches to one foot and a half, with wayboards of red
shale, in parts a sandy and gritty, in others an encrinital and sub-

crystalline limestone.

b. Blotehy grit with much red shale.
c. Hara, fine-grained calcareous grit, passing downwards into a mottled,
dingy green, and purple impure limestone with irregular traces of

wayboards.

d. Purple and white limestone, with olotches of red shale.

432 MR. A. WADE ON THE LLANDOVERY AND [Aug tena,

e. Hard, fine, thick-bedded, calcareous conglomerate, red where weathered,
but greyish when freshly broken. It consists of fragments of encri-
nites, green earth, chocolate-coloured schist, and a few quartz pebbles
of sizes varying from small peas to almonds,

F. The lowest bed visible is a purple and whitish, semi-crystalline lime-
stone, with white veins.’

The shales beneath this sequence belong to the Trilobite-Dingle
Group.

The beds are much faulted in the Park, and vary considerably
within a few yards. In some places most of them become a cal-
careous breccia. They are evidently a very shallow-water deposit,
for evidences of contemporaneous denudation can be seen in the
conglomerates.

Frequently the strata are stained a deep red, on account of
being heavily charged with oxide of iron; but this is not always
the case. When the series is traced to the south, towards Belan,
it is seen to consist of yellow quartzose grits, which are soft,
porous, and in places very fossiliferous. These beds come against
the Bron-y-Buckley Fault, and are either partly concealed by it or
are thinning out considerably. The conglomerates are seen in the
fields on the crest of the ridge at Belan, where they apparently
overlie beds yielding Monograptus flemingi and M. cf. vomerinus,
etc., so that the line of the fault is easily determined. ;

The beds can be traced by the red nature of the soil in the
direction of Welshpool. Where they cross the town, they cause a
steep gradient in the main street.

A conglomerate, consisting largely of limestone fragments, forms
the eastern wall of the Welshpool Dyke, in the quarries at the
southern end: this almost certainly represents the Powis-Castle
Conglomerate. It is altered by contact with the dyke-rock, but
takes on its normal appearance again at Cherry-tree Bank, farther
north, along the eastern flank of the Welshpool Dyke. Here the
strata form a ridge running north-eastwards, and are. exposed
in two quarries—one on the Welshpool Golf-course, the other
in Cherry-tree Bank itself. This ridge ends abruptly in both direc-
tions: on the east it is terminated by the Bron-y-Buckley Fault ;
while on the west it terminates in the fault which lets down the
Welshpool Dyke. At Cherry-tree Bank the strata consist of red
flaggy sandstones, conglomerates, and calcareous beds, all heavily
charged with iron oxide, producing a red soil and staining the
Trilobite-Dingle Shales beneath. Fossils are difficult to find, since
the beds are fossiliferous on only one small horizon. This is in
the quarry on the golf-course, and is the uppermost bed of
quartzose conglomerate immediately under the turf. The beds
are not seen again on this side of the valley. On being traced
westwards, they are seen to thin out. A thin seam of conglo-
merate rests upon Pwll-y-glo Beds, near Ceunant Farm, in the
gorge west of the Welshpool Dyke: it is let down by a fault
which bounds that dyke again on this side. Farther west
the beds crop out again, forming a broad anticline between the
Welshpool Dyke and Cloddiau. The beds are again thicker and
more massive on the western side of the fold. At Cloddiau,

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 4033

between 20 and 30 feet of massive red quartzose conglomerate
merges upwards into red sandy flagstones. The beds are very
ferruginous, and contain large quartz-pebbles, green jaspers,
fragments derived from the lower beds in the sequence, as well
as pebbles of fine-grained igneous rocks of unknown origin. This
conglomerate has been largely quarried for building-stone and
road-metal, but it is now superseded by the rock from the Welsh-
pool Dyke, and the upper calcareous beds of the Gaerfawr Series.
At Cloddiau the group rests on a still higher horizon of the
Caradocian rocks. The Lower Gaerfawr Grits crop out from
under the conglomerate in Harriets Hill on the south; while on the
north, higher beds still emerge in Moel-y-garth. The Conglomerate
itself thins out as it is traced towards Y Frochas, where it loses
its red coloration, and becomes a yellow grit resembling the Mill-
stone Grit. The series ends abruptly here against a fault, and,
owing partly to the thinning-out of the beds over the anticline.
and partly to the overlap of the Ludlow Shales, it is not seen again
between Y Frochas and Welshpool.

At Cloddiau the beds run north-westwards, resting against the
western flanks of Moel-y-Garth, until they terminate against the
Moel-y-garth Fault. Some faulting parallel and subsidiary to that
fault disturbs them in places. At the place marked ‘ Laundry ’
on the map (Pl. XXXIII) they are overlain by about 40 feet
of a grit which weathers in a peculiar manner. The unweathered
grit is hard, blue, and calcareous, and runs in massive beds 6 to
10 feet thick, with wayboards of shale. When weathered, this
grit becomes soft, crumbly, and chocolate-coloured, and it is only
then that it reveals the fact that it is fossiliferous. The strata
have evidently been disturbed, since the shale-bands between the
grits are crumpled and broken in a complex manner.

On the western side of the Moel-y-garth Fault the beds come in
again at Groes-lwyd, and can be traced by Cross Wood to Trawscoed
Hall, where they appear to thicken very greatly and form a wide
outcrop. ‘The apparent increase in thickness is due to gentle
folding in the strata.

It will now be evident that this Conglomerate Series, which
rests in turn upon every member of the Ordovician sequence, forms
an excellent natural base to the Silurian strata of the district.

(2a) Cloddiau Group.—Above the Red Conglomerate Series
from Cloddiau to the Laundry, there is exposed, chiefly in the road-
side and in the stream-section which runs parallel to the road, a
series consisting of 20 to 30 feet of blue shales overlain by about
200 feet of soft, sandy mudstones, with some siliceous flaggy
bands. The beds are very fossiliferous in places, and were considered
by Bickerton Morgan to be of Lower Wenlock age. The fossils
obtained from them, however, proved them to be distinctly of
Llandovery age. They are not well exposed, and appear to be quite
barren in places. The fossils obtained near the Laundry would
seem to indicate the presence of zones of both the Lower and the
Upper Llandovery.

4

434 MR, A. WADE ON THE LLANDOVERY AND [Aves Tenn,

Powis CastTLE CLoppiau & 1
: GROUP. CEFN BEDS. || 5 a
a) 5 ae oe =
2 List or LLANDOVERY FossI1s 5 aS 5
Pe 431-35) 2 | s3| ss
nd 2 (see pp. 5). = Me 25
sy alee 2 | og » ll od | ma
Ele Sues 3 | =| . eel 35 | 28
SSS a lis S| 2 Ee Wee liaee ea
S ® | 8 Been | es > |laee|| so >
ore O}A] oO ix eA <=)
xe Calymene blumenbachi Brong. (From un-| ... *
derlying beds.) |
Climacograptus innotatus Nicholson ......... x
Climacograptus cf. rectangularis M‘Coy ...| X
Climacograptus medius Tornquist ............ x
x Duncanella sp.?.. Beech are acae aie ag an
x a Favosites gothlandica Goldites 0. ie x x
x | | Ravosites aspera d Orbiomy can. 3) | OS ee ee x |X (base)
<x | ... | Favosites Sp... pM Eas) ate in| ex Sa
xX | X | Lindstreemia subduplicata M Coy .. Se ltigece ae
Be xX | xX | Lindstr. subdupl. var. crenulata, » M'Coy cael cae
SKF PR | i nama Pe! Di CoO AS arate / OOS) OP Mala etree $00 a Lae
SC SC ale. Heol Petetiet Bin Tonedale eee: t.).55:06. 0) ie, ha
He x | | Petraia aff. elongata Phillips | Bacal cetyl” eee Me a a
ie | Petraia sp. eM imei. lil... os
ai x Pinacopora graye Niche eth.) 20 ea x
>< . | Streptelasma europeum Roemer . oivedante (evel) Sea Se
Xx res Streptelasma sp. nov. ? aff. breve Ulrich... oxo: | Beiull eecees ea ree
x | ... | Syringopora ct. bifurcata Lonsdale ......... fesse * cep lh eran el oe ee x
x | Monticulipora (?) fibrosa From Lee 1) she ae Xx vee
Goldfuss. + underlying
x Monticulipora lens (?) oD beds. Pea Me ila. _—
s< Callopora sp. she oa sieved ateceslll seepill weld tee i ies
X | ... | Ptilodictya dichotoma Portl. | [ies
... | X | Retepora hisingeri M‘Coy er ate tiers one || 3s: wee
ee cke xX | ... | Stictoporella i ae BM ee cess eae Dieser il) 53. Ae ae
| EO Glyptocrinus sp... More oseaee cece aX eee eee ae an
: x Tentaculites anglicus Salter. ‘(From under- ree || .< |X, (base)
lying beds.) | }
fe Cornulites serpularius Schlothemm.)....)....||... | 2--:|) <1) eee
[>< Murchisonia ct. qyrogona M Coy 0.) eae le eee
x Atrypa mangimalisiMalia. 2.20: ))2..))..2ee XS feral xX
aa Atrypa reticularis Linn. ....... ware x Wx x
x Camarotechia decemplicata Sowerby. one iene alee esx |
| x Camarotechia nucula SOU ged Mamie Gall cota lpec silly OS
x |... | Dayia navicula Sowerby .. Ae ee dl exeal =
|... | X | Leptena rhomboidalis Wilck. (Fr om un-| X x ox x
| pedir 2 beds. So | |
x | ... | ... | Lingula eruwmena Phillips............... if |
ol << elaex Meristella (?) crassa Sowerby ere meer remembers |< | Ox (pas)
a Meristella (2?) subundata M‘Coy ............ | Xe] ae | cco cess emaGnease) |
SAA RENE RR am TL CY CONT LAL ICe ES BUR ibe twee a che a a MeO DG eee | aca |||) 28% Neeces ses
Xo alee | s..)| WMerishinarct) tumida Malis. Were) ea eee ee as x
Orthis rustica Sowerby............... ' ye | x x
Orthis (Dalmanella) testudinaria = ie x
Dalm. | 2 5% |
x | xX | X | Orthis (D.) elegantula Dalm. ae x AIX x x
xX | ... | Orthis plicata Sow. Pes = = |
Orthis cf. calligramma Dalm.......) = | X | . |

1 Dr. Johan Kier, in ‘ Das Obersilur im Kristianiagebiete’ Christiania, 1908 (Vidensk.-
Selsk, Skrifter I. Math.-Naturv. Klasse, 1906, pt. 2), has been able to divide the Llandovery
into stages or zonesin that area. I have therefore compared the ranges of the Llandovery
fossils with those recorded by him. It will be noted that the Powis-Castle Group
correlates very fairly with Dr. Kier’s Etage 6.

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 430

Powis CasTLE Croppiau & | Ry
GROUP. CEFN BEDs. | ap ’
ce F as be
a List or Luanpovery Fossits [continued] 5 @e | BE
: Ge (see 431-35) 2 As abe
we 2 s pp. oO). = MG Ma
a le a |g wy | oe | nA
eh et Sle as = = Rel] 2 5 ® 5
ue S/5|8 24] 28 | £5
See OS | 4 S/A]o la |e | wp
| x . | Orthis calligramma, var. davidsoni Lindstr. eX
| X | ... | Orthis (Bilobites) biloba Linn. ...............| «+ x |X (base)
hee | Orthis bouchardi Dav. ? .............cccceseeees x ase
x Orthis crispata M‘Coy . aa
x Orthis reversa var. mullockiensis Dav. ......| .-
O. (Herbertella) vespertilio Sowerby. x
(From underlying beds.)
=a _| X | ... | Pentamerus(Barrandella) undatus Sowerby x P x base)
x xX | X | Pentamerus (Stricklandinia) lens Sowerby| X | X | X x a
... _ Pentamerus oblongus Sow. acti ae x | X x
.. |... | Pentamerus cf. levis Sow. .. Bete ieee, (acer ulle Oa Be vas
X | ... | Platystrophia biforata Schlotheim. "(From Pall | chetrel Mec el | fae x x
| underlying beds. u
... | ... | X | ... | Pleetambonites sp. ve PY
x | XP]... | ... | Rhynchonella llandoveriana Davidson ...... x a
ooo Es oe Rhynchonella sp. ... Spee DEER see ee
< | X Rhynchotreta borealis Schlotheim ............ | x x
i: x Rhynchotreta cuneata Dalm. na as x
ere Strophomena pecten Linn. baeehiios x | x oo
ae | Strophomena corrugatella Dav idson ......... x bee
leas | Skenzdium lewist Davidson? ...:..........000.] oe |e | x
| xX . | Driplecrminsutaris Wichwald ...........-22.0-.| --. | |i. || x
| X [ee | Triplecia cf. nucleus Hall .............--20-22-| oe | oe | % |] ee |

On tracing the strata round to Y Frochas, we note that they over-
lie the grits there in one or two old quarries where the road crosses
the moorland. They consist of thickly-bedded mudstones, which
are much cleaved and jointed. A few flags occur, but the whole
series seems to be utterly devoid of fossils. In the neighbour-
hood of Powis Castle this horizon does not occur at all, being
overlapped by the higher Silurian beds. The series can, however,
be traced northwards, and yields fossils again in a small quarry at
Llyswen: the strata here are similar to those at Cloddiau, but are
not so thick, nor are the higher beds of the sequence exposed,

(26) Cefn Group.—The Pentamerus-Limestone beds at Cefn
on the extreme east of the map, seem to represent a higher
Llandovery horizon than the limestone associated with the Powis-
Castle Group. The beds consist of massive grey calcareous grit,
with brecciated limestone-bands and some thin beds of shale. The
beds are much broken and contorted by the intrusion of an igneous
rock which is similar to that of the Welshpool Dyke, and was
formerly seen in the quarry-walls.

It will be noted that the fossils, on the whole, indicate an
horizon nearer to Wenlock age than do those which are connected
with the Powis-Castle Beds. It seems, therefore, that the lime-
stone facies spread to this side of the valley at a later period than
in the areas farther west.

43 6 MR. A. WADE ON THE LLANDOVERY AND [ Aug. I9gII,,

(3) Buttington Shales.—The igneous rock intruded at Cefn
forms a well-marked and isolated feature there. On the eastern.
side of the hill, the Buttington Brickworks Company have made a.
large quarry 1n a series of green and purple shales, with which
are interbedded a few bands of hard green flags. About 300 feet.
of nearly vertical strata are exposed, but a careful search through.
the series yielded nothing beyond a few obscure ostracoda. From
the position and lithological character of the strata, they would
appear to be the equivalents of the Tarannon Shales. They crop out
nowhere else in the district, whence it may be inferred that they
either thin out westwards, or are overlapped by the succeeding
Wenlock Shales: the former alternative seems the more probable.
The beds exposed in the quarry show beautifully the effects of ‘creep’
at the surface (see Pl. XXXIV).

(4) Wenlock Shales (eastern facies.)—At Belan, south
of Powis Castle, hard flags and mudstones containing fossils which
indicate the lowest Wenlock zones seen in this area, are faulted
against the Llandovery conglomerate. The beds weather brown,.
and are cleaved and well jointed, wherefore some care is necessary
to distinguish the bedding-planes. Graptolites are to be found only
on the edges of splinters. At the top of the hill, the Wenlock is
overlain by the Lower Ludlow Shales, which now come against the
fault that runs in a direction slightly transverse to the strike of
the beds.

The beds are overlain by drift in the neighbourhood of Powis Park,,
but crop out again to the north of Welshpool, where they are best
seen in Cwm Caethro, a small valley between the farms of Caethro
and Lower Gungrog. Here the beds are much faulted and crumpled,
with some evidence of overthrusting. Despite this disturbance,
three well-defined Wenlock zones can be established (fig. 5, p. 437).
The outcrop of the beds is very narrow, compared with that of
the overlying Silurian; but no reliable estimate can be formed of
their thickness. They consist of earthy mudstones and blue flags.
The Cyrtograptus-linnarssoni Zone is probably concealed by faulting,
while the zones of C. murchisont and C. symmetricus usually seem
to be absent in this part of the Welsh Borderland. Against these
beds, by a small waterfall in the stream, come Lower Ludlow
Shales, bearing Monograptus varians and M. vulqaris, the whole
of the beds being crumpled and overfolded at the junction.

From Cwm Caethro, the series can be traced into Trelydan
Dingle, at the head of which, just under Trelydan Cottage, strata of
Wenlock age are to be seen folded into an anticline against the
Trilobite-Dingle Shales. At first sight, the appearance suggests
Llandeilo Flags, cropping out from under the Dicranograptus Shales;
but the paleontological evidence proves the existence of a great fault.
at this point. The beds consist of a blue earthy limestone, con-
taining in places numerous little cubes of pyrite, overlain by hard,
calcareous, gritty flags. Only the limestone-band yielded fossils,

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 437
and these are indicative of Wenlock age, Pentamerus linguifer
being most common. The exposure is very small, but it is interesting
tto find the Wenlock-Limestone facies extending to this district.
The bed is only 2 or 3 feet thick, and may be merely a local deve-
lopment; it is very similar, however, in its lithological peculiarities
ito the Wenlock Limestone of Wenlock Edge.

Fig. 5.—Map illustrating the exposures in Cwm Caethro.

I
i
vit

--—.—.

~
o G
= 1
at
Bue
So8
° 9
<9 2 Gg BPO S DEN LICH ss ee
=
3 > & Beds crumpled_.____— wy
2 ; OULUGS Ses —
3
N ee ae a

ee

(Western facies).—Passing from the eastern side of the district
over the anticline of Guilsfield Valley to the west, we find a most
interesting outlier of Wenlock Shales resting directly upon Gaerfawr
Beds at Tyn-y-llwyn, near Little Pwll-y-glo.

The graptolite fauna shows that shales of the zone of Cyrto-
graptus lundgreni were deposited over the anticline, contrasting
with the Llandovery conglomerates which thin out-over it. It is
evident, therefore, that a folding movement had already commenced
before the deposition of the Llandovery Series; and a ridge of
Gaerfawr Beds, which are thin here and have evidently been much
denuded, formed an island in Llandovery times. This ridge was
finally submerged in the Upper Wenlock period; and it will be seen
that the submergence was finally more complete in Lower Ludlow

times, since the Upper Wenlock Beds along with the Llandovery Beds

438

MR. A. WADE ON THE LLANDOVERY AND

(Aug. EOE,

are completely overlapped between Powis Castle and Y Frochas.
In the stream-section running down the west side of Y Frochas to.

Ty-brith, strata of Wenlock age again occur.

Fig. 6.—Map showing the Wenlock zones
exposed in G'uilsfield Brook.

: oo
pil?
¢ M-

Llandowery ¢°
Mudsbones fo Moel-y-garth Farm
Laundry: --

—O-

[Seale:- 6 inches =1 mile.]

<
SS

GLO tLittle Stonehouse
ey lley.
P peod>
4 Zone f
= Te, lundgren;
Z 2
sae Me Tigidus
+ { — ==
peiler gles = f30°> ~~ riggpas
_ 7 GE Lone of |

ft

The basement beds
are sandy flagstones,

but above they
change to blue flags.
and shales’ with

massive mudstones,
which contain what.
have been described
as ‘large concretions
of limestone.’ In
this case, I doubt
the concretionary
nature of the frag-
ments, but think
rather that they are
boulders of an early
Wenlock or late
Llandovery _ lime-
stone, broken up
during a period of
denudation which
accompanied the
overlapping of the
upper beds already
noticed at Tyn-y-
llywn. This is sug-
gested by the fact
that some of the
blocks are brecciated
limestones or lime-
stone-conglomerates,.
which could hardly
be concretionary.
The circumstance
that the zone of
Cyrtograptus lund-

grent rests upon
these brecciated
beds, shows that.

the overlap of the
Wenlock Shales fol-
lowed closely upon

a period during which the Llandovery Beds were being subjected

to denudation along the axis of the anticline.

In Guilsfield Brook,

between Coed-y-garth and the Park Farm, the zones of Cyrtograptus
linnarssoni, C, rigidus, and C. lundgreni are fairly well seen (fig. 6) ;

it is possible, however, that other zones may be present.

Fragments.

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 439

of Cyrtograptus are common in each of these zones, but many of
them could not be determined.

The beds pass up into strata of Ludlow age, the’ zone of
Monograptus nilsson being observed near Moel-y-garth Farm.

(5) Yr Allt Group.—The Ludlow Shales form the most wide-
spread division of Palaeozoic rocks in the area. They are, as a
rule, uniform in character, and consist, on the lower horizons,
chiefly of pale thinly-bedded shales, soft and muddy, but tend to
become hard, flaggy, and calcareous above. The highest beds are
thin flaggy sandstones, but these are only seen in one locality, the
top of the Yr Allt escarpment.

A surprising feature of these soft shales is the way in which
they occupy the crests of the highest hills; but this is explained by
the fact that, wherever they so occur, they are much faulted and
crumpled, ‘They appear to have suffered greatly in the movements
which have affected the district, and in several places small over-
thrusts can be detected in the Wenlock and Ludlow. In the Cefn
area, the beds have already been described by Miss Elles and
Miss Wood (Mrs. Shakespear).

These beds form a long line of escarpment running north-north-
eastwards from Belan to the Severn, broken in the middle by the
Welshpool Gap,’ in which they are hidden by drift and alluvium.
The strata are folded against the Bron-y-Buckley Fault into a long
narrow anticline and syncline. From the core of the anticline
the Wenlock Shales crop out; but against the Bron-y-Buckley Fault
a thin strip of Ludlow Shales is usually found. This is seen in
the quarries on the top of the hill at Belan (where Ludlow Beds
succeed Wenlock against the fault), and at the southern end of
Bron-y-Buckley Wood.

Below Cwm Caethro the zone of Monograptus scanicus occurs
opposite Lower Gungrog Farm, where the strata consist of
strongly-jointed dark-grey mudstones and shales weathering brown
(fig. 5, p. 437). They are broken by a couple of faults between
the farm and the orchard. This zone extends into the orchard,
where beds yielding Monograptus varians, var. [3 Wood, come in.
Above the orchard, the zone of M. nilssoni, consisting chiefly of
soft earthy shales, with occasional bands of harder mudstones, can
be traced right up to the waterfall, where the stream leaves the
uppermost wooded dingle.

Farther north, the strata are more flaggy and calcareous. The
form a magnificent and bold escarpment in the cliffs of Yr Allt.
The lower part of that escarpment is concealed beneath screes ;
the upper part, consisting of hard false-bedded flagstones with a
few thin shaly horizons, has been well quarried in places. Few

1 See my ‘Note on the Glacial Geology of the Area,’ to be published
separately.

440 THE LLANDOVERY ROCKS OF MONTGOMERYSHIRE. [Aug. IQ1T.

fossils oceur, and these suggest the upper zones of the Lower
Ludlow. .

At Derwen-deg the shales are so well cleaved that the bedding-
planes are hard to distinguish, but fragments of Monograptus nilssont
were found on the edges of splintered pieces. A thin series of
calcareous sandy flags rests upon the hard flags of Yr Allt cliffs,
in the lane-section about 300 yards north of Spout House. These
beds yield myriads of Dayia navicula, together with an assemblage
of fossils which suggests the horizon of the Aymestry Limestone’
or the uppermost beds of the Lower Ludlow [10, p. 488].

In the Park of Powis Castle, the Ludlow Shales are seen on the
west side of the Castle, resting almost directly upon the Powis-
Castle Conglomerate Series. ‘They form the highest ground in the
Park, and are much crushed and contorted. They evidently
overlap the Wenlock Series, or are brought in by a fault parallel
and subsidiary to the Bron-y-Buckley Fault.

The beds form a high ridge, which runs north-north-eastwards
to Nant-y-caws Brook. The country here is much covered by drift;
but the Ludlow strata appear to swing round in a great curve to
the west, overlapping the underlying beds on the axis of the Guils-
field Valley anticline. They form an escarpment running almost
due east and west as far as Glyn, where it again takes up the
north-easterly direction. North of Glyn, Monograptus colonus occurs
in extraordinary abundance in some exposures. The graptolites are
preserved in limonite probably after pyrite, and so their presence
renders the beds quite rotten and crumbly.

The Lower Ludlow Beds cover a very wide tract on the west of the
area, and numerous excellent exposures occur, notably near Trefnant
and The Park. ‘The strata are much folded; they consist of brown
flags and shales, which pass upwards into blue flags containing an
extraordinary number of calcareous concretions or septaria, locally
called ‘ cannon-balls.’ These differ considerably from the limestone-
blocks seen in the Wenlock Shales at Ty-brith. The blue flags often
contain numerous specimens of Monograptus colonus arranged in
star-like patterns on the bedding-planes. Nearly the whole of this
outcrop belongs to the zone of M. nilssoni, a species which is very —
abundant. This zone is evidently very thick—not less than 400 to
500 feet in the neighbourhood of Trefnant. The underlying zone
is rarely exposed, and is apparently not so well developed. The
rolling of the beds, however, renders accurate measurement difficult.

Higher zones are doubtfully present, although the barren flags of
Tir-newydd are similar in character to the flaggy beds of the
upper part of the Yr Allt escarpment, and may represent the upper
division of the Lower Ludlow.

1 Miss G. L. Elles & Miss I. L. Slater, ‘The Highest Silurian Rocks of the
Ludlow District’ Q. J. G. 8. vol. 1xii (1906) p. 197.

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24

Q.J.G.8. No. 267.

ra

449 THE LLANDOVERY ROCKS OF MONTGOMERYSHIRE. [Aug. 1grI.

WENLOCK. Lupiow SHALES.

List of WENLOCK AND LUDLOW
FossiILs OTHER THAN GRAPTOLITES.

| Ty-brith.
Trelydan
Dingle

| Cwm Caethro.

| Spout House.

| Powis Park.

| Belan.
| Gungrog.
| Yr Allt

ede ASE SI ae Phacops longicaudatus Murchison ......
wa fl ae | see |... || Ceratiocaris pardoéana I.a Touche
... | ... || Orthoceras primevum Salter sie
xX |... || Orthoceras subundulatum Portlock ......
| Orthoceras gregarium Sowerby .........
Orthoceras canaliculatum Sowerby MPM es oe!
a tf]... |... |... || Orthoceras cf. imbricatum Wahl. ...... oa [iad ol ea ene
Peeler! vcs. 2 ||| \Onehoceras sp... Pte
| Phragmoceras nautilewm ‘Sowerby Pek x
Lituites cornu-arietis Sowerby ......... x
.. {{ .. | .. |... || Camarotechia cf. nucula sung Nae ae
bt tle |. |.) || Dayia nantenla Sowerby... ...
| .. |... | ... || Leptena rhomboidalis Wilck. . ae tek eee
| ... |... | ... || Orthis cf. actonie Sowerby . ietikecke|oces Nha eagh aaa Oo
xX |... | ... || Pentamerus linguifer Sowerby — SESeao Te
aaa aaa P. (Barrandella) undatus Sowerby ...
... | .. | ... || Pleetambonites sericea Sowerby .........
i| X |... |... || Rhynehonella sp. a, ese
ie Strophomena ct. filosa Sowerby - eee

< | Belan.

x
oso

Spee
x

PSS SGA | Trefnant.

x
KOS:

| Sefedlivcsy neem (i GeTeper CL comers ELAM Vote ae ee
| xX |... | ... || Wilsonia wilsont Sowerby .... was i eg] ea
evel eal vice Maco ve SOI 1 aC heavals spharoidalis MCoy sen, [eae eeu

2K Mi KX:

Cardiota wmterrupta Brod. .......:.....:| XK |... | Kee en
Pterinea retroflexa Wahl. eg site pe
Pterinea tenuistriata M‘Coy ............
Cornularia subtilis Salter ............... 1% ia aes
Ostracod ae. 22557 dite ein dendcc dais | athe do See eee i) Saat ee

OO

Kir tot

1 These beds are possibly of Llandovery age. (See p. 438.)

+ VI. Srructrure oF THE AREA. (Section ITI, fig. 7, p. 443.)

‘The structure of the two valleys dealt with in these pages is by
no means simple. Broadly speaking, the strata are folded into two
parallel anticlines with north-north-easterly and south-south-

' _-westerly axes, the eastern anticline occupying the Valley of the

_ Severn, and the western the Vale of Guilsfield. Between the two

is a crush-zone, consisting of two smaller anticlines crushed against

the Bron-y-Buckley Fault, and separated by the Welshpool Dyke.

The Welshpool Dyke is probably of the nature of a horst, carrying

with it the Trilobite-Dingle Shales, while Silurian strata are let
down on either side.

The Bron-y-Buckley Fault is practically a strike-fault, and

| so there is but little lateral displacement of the outcrops. The |

__. amount_of the throw can be surmised by the fact that, at the

entrance to Trilobite Dingle, Ludlow Shales are thrown against

the Trilobite-Dingle Beds. Since, however, we must allow for the

Fig. 7.—Generalized section from east to west, illustrating the structure of the area.

Tc
_

o
Pa)
=
3
i)

Vale of

Moel-y-garth
|
|

Yr Allt Beds.

Powis-Castle Beds.
a = Trilobite-Dingle Shales.

é

Pwll-y-glo Beds.

Dyke.

e'. = Tarannon Shales.

b
D

Bron-y-Buckley Fault.

Wenlock Beds.
Gaerfawr Grits

Vi
¢
B

Gwern-y-brain Shales,

Moel-y-garth Fault,

9g
-d
A

fact that the Llandovery Beds here
rest directly upon the Trilobite-Dingle
Shales, the throw is only to the extent
of the thickness of the Llandovery
and Wenlock—probably about 500 feet
on the east.

On the western side of the district,
the Moel-y-garth Fault lets down the
Silurian to the west, and the throw seems
to be of greater amount than that of the
Bron-y-Buckley Fault. The Moel-y-
garth Fault is a dip-fault, and causes a
displacement in the outcrop of upwards
of half a mile, bringing Wenlock zones
against the Caradocian of Moel-y-¢ ~th.
The direction of this fault seems to be
the normal one of the district, and several
subsidiary faults run parallel to it.

The two main faults would appear to
come together under the alluvium to the
north of Guilsfield, and this effect is
what might be called a ‘ keystone-fault,’
or ‘ inverted trough-fault’: the former
term is perhaps the more expressive.

I am of opinion that some of the
apparent overlap of the Silurian beds,
especially the Ludlow Shales, is pro-
bably due to overthrust accompanying
normal faulting. This is difficult to
prove, on account of the nature of the
beds ; but it is a significant fact that,
wherever these soft and rotten Ludlow
Shales occur, they occupy high ground
and are much contorted and crushed.
Small overthrusts can readily be distin-
guished, especially in Cwm Caethro; but
the overthrusting suspected would be on
a larger scale. It seems probable that,
in the movements which brought about
the folding and faulting of the area, the
lower and more consistent beds bent or
broke under the pressure, while the soft
shaly beds above would tend to move
forward over the beds beneath. This
phenomenon can be seen on a small
scale, in almost any quarry where hard
beds including shaly bands are folded.
Such overthrusting in the Silurian beds
has been noticed by Prof. Reynolds in
the Tortworth Inlier,* and by the present

? «On the Fossiliferous Silurian Rocks of the
Southern Half of the Tortworth Inlier’ F. R. O.
Reed & S. H. Reynolds, Q. J. G.S. vol. lxiv

(1908) p. 535.
oe 2

444 MR. A. WADE ON THE LLANDOVERY AND (Aug. I9II,

writer in the southern end of the May-Hill Inlier.' The Silurian
strata do, however, overlap the lower beds, each group in turn
creeping over the underlying group.

The overlap of Powis-Castle Beds has already been traced across
the map. It is accompanied by the thinning-out of these beds
over the anticline of the Guilsfield Valley. This is first suspected
on account of the disappearance of the conglomerates and associated
beds between Welshpool and Y Frochas, is confirmed by the fact
that the conglomerate is onlysrepresented by a very thin bed
(perhaps a foot or two thick) on the west side of the Welshpool
Dyke in the Ceunant gorge, and is absolutely proved by the outlier
of Wenlock Shales at Tyn-y-llywn, which rests directly upon the
Gaerfawr Grits with no intervening Llandovery Beds. Here,
therefore, the conditions are exactly the same as at Rhayader,
where Dr. Herbert Lapworth has accounted for peculiarities in the
distribution of the Llandovery (Caban) Conglomerate in the same
manner.”

It would seem, then, that the whole of the Welsh Border was
dotted with a chain of islands in Llandovery times, due to the fact
that folding along north-easterly and south-westerly axes had
already commenced. The Llandovery conglomerates were laid
down in the synclinal depressions, and this accounts for the rapid
changes noted in both the thickness and the lithological characters
of the beds over limited areas. The islands were submerged locally
in Wenlock times, and the overlap of the Ludlow, shown at the
southern end of the map (Pl. XXXIII), which is probably true
overlap, indicates further subsidence at a later period.

VII. CorRELATION OF THE STRATA.

In attempting to correlate the sequence with that of other areas,
I paid visits to other Welsh and Border districts—so as to
make my comparisons, as far as possible, dependent on personal
observation.

(1) Shelve.—It would naturally be expected that a close simi-
larity would exist between the Ordovician succession in the Welsh-
pool area and that of Shelve, only 6 miles away to the south-east.
Nothing, however, could be more different. The Rorrington Flags
may correspond to the Trilobite-Dingle Shales ; but the alternating
shales and ashes above them have no counterpart in the Welshpool
area, unless it be in the ashy grits which occur along with the
limestone development in the Gaerfawr Grits of Gwern-y-Brain.
These may correspond to the Whittery Group.

(2) Caradoc.—Travelling 20 or 30 miles to the south-east, we
come to an outcrop of Ordovician rocks which agrees tolerably well
with the succession here described. The sequence in the Caradce

1 During field-work under Prof. W. W. Watts in 1907.
2 «The Silurian Sequence of Rhayader’ Q. J. G. S. vol. lvi (1900) p. 117.

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MON'TGOMERYSHIRE. 440

area itself is surprisingly like that succession.’ It appears, how-
ever, that the succession in South Shropshire is not complete.
Representatives of the Pwll-y-glo Group do not seem to occur,
while the Ashgillian has not previously been recognized. I would,
however, correlate the black shales of Gwern-y-brain with the
Trinucleus Shales of the Onny River, placing the latter in the Ash-
gillian of Dr. Marr. This I have confirmed, and I may here record
for the first time the fact that I have found Diplograptus (Ortho-
graptus) truncatus yar. socialis in considerable numbers in the
Trinucleus Shales. This would correlate the horizon with the
Barren Mudstones and the zone of Dicellograptus complanatus at
Dobbs Linn, and would place them in the lower part of the
Ashgillian. It would seem, therefore, that the Shelve area was in
all probability isolated from the Welshpool district in Caradoc
times, just as it was from the Caradoc area, and that the beds in
the former area were laid down in a northern?extension of the Caradoc
Sea which swept round the Longmynd. If this be so, there is
in all probability a prolongation of the Longmynd ridge under the
Long Mountain.

(3) The Long Mountain.—The Silurian succession in the
Long Mountain [7] [9] [10] is similar in most details to that of
the Welshpool area. The graptolitic zones, absent in the Long-
Mountain succession, are absent here also. There are, however,
one or two points of difference, the principal being the occurrence
of limestones, locally, in the Wenlock Shales. Nor does the zone
of Monograptus vulgaris seem to be so well developed in this
western area; otherwise the zones correspond fairly well.

(4) South Wales.—The strata here are easily correlated,
although deep-water conditions seem to have lasted in South Wales
right through the Caradocian period. Unfossiliferous black shales,
overlying beds with Z'rinucleus seticornis and underlying mudstones
which contain fossils somewhat similar to those of the Powis-
Castle Beds, occur near Haverfordwest, and may represent, in part,
the similar shales of Gwern-y-brain.?

(5) Central Wales (Rhayader).—There are some points of
resemblance and some points of difference between the succession at
Rhayader * and the sequence at Welshpool. The characters of the
‘cleaved black slates’ agree almost entirely with those of the black
shales of Gwern-y-brain. In Gwern-y-brain, however, they are
not cleaved and are, in places, very fossiliferous. Moreover, at
Rhayader, these black slates apparently pass up conformably into

* C. Lapworth & W. W. Watts, ‘The Geology of South Shropshire’ Proc.
Geol. Assoc. vol. xiii (1894-95) pp. 312, 319-20.

2 F. R. C. Reed, ‘The Base of the Silurian near Haverfordwest’ Geol. Mag.
dec. 5, vol. iv (1907) pp. 535 et segq.

° H. Lapworth, ‘The Silurian Sequence of Rhayader’ Q. J. G. 8S. vol. lvi
(1900) pp. 124 e segg.

446 MR. A. WADE ON THE LLANDOVERY AND [Aug. 191T,

the lowest member of the Valentian, and the unconformity with

accompanying conglomerates occurs later. In Gwern-y-brain, the

unconformity along with the conglomerate stage appears to occur
at, or very near, the base of the Valeatian. Other points of simi-
larity between the two areas have already been mentioned.

(6) North Wales.—On visiting the Bala area itself, I found
many points of similarity; but, although the work of Thomas
Ruddy* established the general succession in this area, the sub-
division of the sequence and its exact correlation still remain to be
done. The lists of fossils from the Lower Bala Limestone of Bala
are closely comparable with those drawn up from the limestone
horizon in the Gaerfawr Grits. I have, therefore, chosen the
succession worked out by Miss Elles at Conway” as presenting
the most complete sequence that I could get in North Wales for
comparison. Shales predominate in that district, yielding many
graptolite horizons, whereas shallower-water conditions existed at
Welshpool and graptolites are not so abundant; and yet there is a
good deal of similarity between the paleontological succession in

both areas.

(7) The Lake District.—Curiously enough, it is when we come
to the Lake District and the Scottish (Girvan) area, that we find
the closest and most complete similarity, especially in lthological
characters. ;

There are many points of resemblance in the lower part of the
sequence developed in the Lake District. The limestone develop-
ment in the Gaerfawr Grits seems to correspond very well with
the Applethwaite Limestone; while the position and characters of
the Ashgill Shales and Staurocephalus Limestone are very similar
to those of the Gwern-y-brain Shales and Limestone. ‘The uncon-
formity, seen at the top of the Ashgillian in the Welshpool area,
does not appear to be present in the typical area, and so the Powis-
Castle Group can only be correlated on paleontological grounds.

(8) Southern Scotland (Girvan area).—Here, again, the
sequence is similar. There are some surprising similarities in
the paleontological character of the beds: for instance, the
abundance of gasteropods at certain horizons in the Caradocian.
The Pwll-y-glo Beds probably correspond to the Ardwell Flags,
the graptolites present in them indicating that horizon.

VIIL. Ienzovs Rocks—Tur Wetsuvoon Dyxs.

The physical characters of the Welshpool Dyke have been very
fully described by Murchison [1]. I have little to add to his
account, so far as its texture and appearance are concerned. It
illustrates very well the internal structure of a large dyke, and is

1 Q. J. G. S. vol. xxxv (1879) pp. 200-208. See also A. J. Jukes-Browne,
Student’s Handbook of Stratigraphical Geology ’ 1902, pp. 109-12.
2 Q. J. G.S. vol. Ixv (1909) pp. 171-72.

ee - s A i Se er ee ae ee Oa .6hCUre
E> “h ’ Vir ° P a :

| Z'o face p. 446.

OF THE ORDOVICIAN ANDPSE OF OTHER AREAS,

North-Eastern District | Southern Scotland
Montgomeryshire. F . | (Girvan: Area).

Zones of
(4. M. leintwardinensis ?
lt J 3. M. scanicus. bes. Mudstones and shales of
eds. 2. M. nilssoni. Lanark.
li. M. vulgaris.
its.
(4. Cyrtogr. lundgreni. :
nlock J 3. C. rigidus. Straiton and Bargany
les & |} 2. C. linnarssoni. s. | Beds.
estone. 1: M. riccartonensis.
MeN. sie | —-—- —— -
tington Shales. ds. Parkhill Group.
ddian Mudstones.
| s. Canregan Group.
vis-Castle Conglomerate | Saugh Hill Group.
and | Mullock Hill Group.
simestones.
aconformity.) ee om LS Mer ley Gatnaet sant Maca ay «
: ( Black shales.
. | es.
vern-y-brain ; Drummuck Beds (with
Eroup. Staurocephalus).
| |
| Limestone. lus
stone,

| ( Limestone and ashy — IP plethwaite | Shallock Flags.

|) Serie Limestone.
erfawr | | Whiteliouse Beds.
Baa. ‘ onglomerate. |

ile-End Beds. Ardwell Flags.
| Grits and flags. |

l-y-glo Group. | Grits and
js mind SEEN | Balclatchie Beds. sandstone.
obite- Dingle Shales. Shales.

Quart. Journ. Geol. Soc., Aug. 1911.) [To face p. 446,

TABLE ILLUSLRATING THE CORRELATION OF THE ORDOVICIAN AND SruuRIAN Rocks or Norra-Easrern MontGOMBERYSHIRE WIEH THOSE OF OTHER AREAS,

wee ee ea a |
| North-Eastern Central Wales North Wales Ee Sk Southern Scotland
Series. South Wales. Montgomeryshire. Caradoc. (Rhayader), (Conway). Lake District. | (Girvan: Area).
Zones of
(4. MW. leintwardinensis ? |
ee Att J 3. ML. seanicus. Coldwell Flags. Mndstones and shales of
LupLow. Beds. 2. M. nilssoni. anark.
“ 1. M. vulgaris. |
; Coldwell Grits.
BanoEta®. 4. Cyrtogr. lundgreni. :
WENLOCK, Wenlock } 3. C. rigidus. | Straiton and Bargany
| Peales & ) 2. C. linnarssoni. Benarth Flags and Grits.| Brathay Flags. | Beds.
Limestone. (1. WM. riccartonensis.
( ‘TARANNON. | Buttington Shales. Rhayader Pale Shales, Browgill Beds. | Parkhill Group.
|
Gyffin Shales.
VADLENTIAN. | Upper Luanpovery.| Green mudstones Cloddiau Mudstones. Caban Group.
& grits.
| Shales and ; (Uncontormity.) Skelgill Beds. Canregan Group.
Lower Luanpovery. sandstones. Powis-Castle Conglomerate Saugh Hill Group.
Unfossiliferous black and Gwastaden Group. Conway-Castle Grits. | Mullock Hill Group.
shales. Limestones. | |
ine. ae a a Slade Beas. icon fox mut 92) Phyllopora Beds ?
( Black shales.
| Redhill Beds. f | Cleaved black shales. Deganwy Mudstones. Ashgill Shales. | :
ASHGILLIAN. Gwern-y-brain | Drummuck Beds (with
| Sholeshook Limestone. Group. | Staurocephalus).
Robeston Wathen (Limestone, | Trinucleus Shales. Bodeidda Mudstones. Neadirocepha ay |
Limestone. | i :
ae cet a as bce se Re | eae ie Shee
( Limestone and ashy | | Applethwaite | Shallock Flags.
| grits. | Acton-Scott Beds. | 5 Limestone. | :
CARADOCTIAN. Gaerfawr | | Longville Flags. Upper Cadnant Shales. /Sleddale | Whitehouse Beds.
on 5 Group. Chatwell & Soudley | | Conglomerate. |
Dieninograpis | | _Sandstones. — Stile-End Beds, Ardwell Flags.
Shales. Grits and flags. | Honrsidge Grits. and |
Pwll-y-glo Group. arnage Shales. | | : ~ Grits and
= a=== = 7 = Roman-Fell | Balelatchie Beds, J sandstone.
GuENKILN-HAR?rELL. Trilobite- Dingle Shales. | | Lower Cadnant Shales. | Group. | (L Shales.
| ee E as See, MEAN BMA EEY fee at ee iii

Pape Are we

Pee eer 4

x Romapaene:

weet
a i

a i Up a Waa oa

Su eniay.: ss

rs

4
%

ecru

ane hater

UB OOM ei e

Koons

Pe wera ee ere cee IM eo Sh

Vol. 67.] ASSOCIATED ROCKS OF. NORTH-HAST MONTGOMERYSHIRE, 447

made up of parallel layers of roughly hexagonal columns, each column
sloping a few degrees from the horizontal. ‘The walls separating
the layers are almost vertical, dipping about 80° to the east of south-
east (see Pl. XXXYV, fig. 2). The rock is fine-grained and light
green in colour, with a specific gravity of 2°72, when fairly fresh.
Under the microscope the structure is trachytic : the rock is seen to
consist of small idiomorphic plagioclase-felspars arranged in lines
of flow, with a certain amount of chloritic ground-mass, and a few
tiny grains of augite where the rock is fairly fresh. Small patches
of chlorite (probably ripidolite) show a radiating arrangement, when
examined under the higher powers of the microscope (see fig. 8,
below). Some grains of magnetite, pyrite, and graphitic material
occur; while calcite becomes so abundant near the walls of the
dyke, that the rock will effervesce with acid. The last-named
mineral has evidently been derived from the calcareous breccia or
conglomerate, which is seen resting against the eastern face of the
dyke. The chlorite is probably the decomposition-product of a
ferromagnesian mineral. There is an entire absence of porphyritic
constituents, which were also absent primarily.

Fig. 8.—Bostonite of the Welshpool Dyke, showing radiating
aggregates of chlorite-crystals.

= FS

[Magnified 50 diameters. |

The rock is somewhat similar to that of the intrusive dykes of
Cefn and the Breiddens, where the original ferromagnesian mineral
was described by Prof. Watts as being hypersthene [4] [7] [12].
These rocks have also been discussed by Mr. H. 8. Jevons [11], who,

448 MR. A. WADE ON THE LLANDOVERY AND [Aug. IgIT,

finding the felspathic constituent to be albite, suggests that the
rocks are not diabases, as Prof. Watts had called them, but kerato-
phyres. In order to settle this point with regard to the rock of the
Welshpool Dyke, I first made several tests with the felspars. Using
Becke’s method, I obtained results which indicated albite. Not
being satisfied, I employed microchemical tests. By means of
Boricky’s methed—using a 4 per-cent. solution of hydrofluosilicic
acid—I obtained weakly double-refracting hexagonal crystals of
sodium silicofluoride (Na,SiFl,) in great numbers, together with
isotropic cubes and octahedra indicating potassium silicofluoride.
Finally, I decided to make a series of analyses of the whole rock.
The results indicate a rock nearer to bostonite than to keratophyre,
and this would agree better with the microscopic characters. The
absence of porphyritic constituents, the presence of marked flow-
structure, and the fact that the rock is intrusive, are all in favour of
it being called a bostonite, and against the term keratophyre
being used in connexion with it. Mr. Jevons, in fact, states that
an occurrence described by him from the Berwyn Hills is probably
the first recorded of an intrusive keratophyre, while bostonites
typically occur in dykes. I append the analyses, together with
those of recognized bostonites obtained from two other localities :
it will be seen how closely the results agree.

CoMPARISON BETWEEN ANALYSES OF THE WELSHPOOL-DyYKE ROcK AND
SIMILAR ROCKS FROM OTHER LOCALITIES.

Conginiene Welshpool | Welshpool.| Bostonite. | Bostonite.

a (No. 1). (No. 2). Cowal. | Orkneys.
SOs 2. eigen: ea dee oe. 54:17 54:15 56-4 52-00
UANSO),. ERO sere 3 12-96 LWT | 19-0 18-06
He,O... Rees sees: 5°09 2°06 35 2°18
eO 7, aie eee oe 6°49 5°50 4:8 5:14
MeO 2 Soe eae eee ne 2-94 0°66 15 2°84
CAO se ee en 9:00 10°44 2°6 4:59
Na O). pase eee 1-52 1-42 4:5 3°78
KO °c BA eeeeaee toe 5°64 5°55 50 4-68
EV Ore cc eeagatacneos cece 0°62 0°64 2°6 1-84
DO) sic: «tetesecoensa eee eae 1:09 POS. Alek Measnce 0:98
COs, Vi cacsstescee ene gts OMNI RRR EE Seeeo pell pladl Pc 3°59
Mn@ 7230.2 ae Hitegecense | 2, |, aeemenaee hi ame tae 0:25
TL OCGUS cc. See 99°52 99°64 99-9 99°93

1 F, H. Hatch, ‘ Text-Book of Petrology’ 5th ed. (1909) p. 231.

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 449

IX. Nores oN THE PALZONTOLOGY OF THE AREA.

(1) Trilobita.

TRINUCLEUS INTERMEDIUS, sp. nov. (Pl. XXXVI, figs. 1 & 2.)

Trinucleus concentricus Hall, ‘ Paleontology of New York’ vol. i (1847) p. 249
& pl. lxv, figs. 4a-4¢; also p. 255 & pl. Ixvii, figs. la-Lh.

Length =18mm.; width =21 mm. General form almost circular.
Head-shield semicircular, widest across the junction with the body-
segments.

Fringe flat or concave in front, sloping downwards at about 60°
at the genal angles, where it is produced backwards into long ears
which reach to the tail. Spines straight and parallel, continued
beyond the tail to a distance equal to the length of the main part
of the test. Glabella pyriform and swollen, not equal in width to
the cheeks, encroaching slightly in front on the fringe, posteriorly
carinate. Base of the glabella narrow, with an obscure neck-furrow,
which is continued along the posterior edge of the cheeks, where it
bends abruptly at the margin of the ears. Cheeks swollen and
wide, quite smooth. In the anterior part of the fringe are five
rows of pits, the three posterior rows being of equal size, the two
outer rows smaller. The three inner rows are concentric and radial ;
in the outer two rows the pits are smaller and more numerous, and
therefore some of them take positions intermediate to the radii of
the inner rows. The two innermost rows are separated from the
others on the lower surface of the fringe by a ridge which runs
round to the genal angles. At the genal angles, and in the space
between the front of the glabella and the cheeks, the number of pits
increases: in the former case to seven rows, in the latter case to
six. The fringe has a thick flattened rim or edge along its outer
margin.

The body is equal in length to the tail, but both together are
only two-thirds of the length of the glabella and fringe. The body
consists of five or six flat joints, the axis alone being convex. The
first three joints are overlapped at their margins by the ears of the
fringe. The axis is narrow, about a sixth of the width of the
thorax. Pleure narrow, horizontal and flat, but curving slightly
backwards at their outer extremities. They are grooved with a
furrow which is almost parallel with the edges of the pleure.
Pygidium subtriangular and flat; anterior margin slightly rounded
and thickened. Axis conical and elevated; markings of rings and
furrows on tail very obscure.

Remarks.—This remarkable species is readily distinguished from
Trinucleus concentricus* by the large pendent ears of the fringe
and the direct backward extension of the spines. The front of
the fringe is more evenly semicircular than in Tr. concentricus,

1 J. W. Salter, Q. J. G. S. vol. iii (1847) pp. 251 et segg. [The Trinucleus
ornatus there described is now recognized as 77. concentricus. |

450 MR. A. WADE ON THE LLANDOVERY AND [Aug. Ig1I,

while its concave character also serves to distinguish it. The
carinated glabella, too, is a characteristic feature.

From Trinucleus loydit' it is distinguished by the subtriangular
tail, which approximates in shape to that of Zr. concentricus.
The concavity of the fringe is not so marked as in 7’. lloydii,
while the indentations in the furrow surrounding the glabella in
that species are either obscure or absent. The arrangement of the
pits in the fringe is also different: in Z'r. lloydii the pits are more
closely set on the inner margin, while in Zr. intermedius they are
more closely set on the outer margin of the fringe. The species is
distinctly intermediate in character between Z'r. concentricus and
Tr. Uoydii.

Hall’s figures of 7. concentricus seem to be nearer to Tr. lloyd
than to Tr. concentricus. They correspond with 7'r. intermedius more
closely than with either, and differ chiefly in having shorter spines.
The species figured in his pl. lxv differ also in the disposition of
the pits, the larger pits being on the outside of the fringe. Those
figured in his pl. lxvii correspond more closely in this respect.
The grooves in the furrow, round the glabella, characteristic of
T. lloydw are obscurely indicated in Hall’s figures. The tail, how-
ever, is subtriangular, and the glabella encroaches on the fringe,
both features characteristic of 7'r. intermedius, and not of T’r. lloydi.
On the whole, therefore, Hall’s species correspond more closely to
the species now described, although they are slightly nearer to
Tr. lloydii than is the new species, thus affording a further link in
the chain of evolution.

Horizon and locality.—Trilobite-Dingle Shales, Welshpool.

DionipE sp.? (Pl. XXXVI, fig. 3.)

Length =11°8 millimetres ; width =12°5 mm. Shape nearly cir-
cular. Head equal in length to rest of body. Glabella large, almost
circular, slightly contracted behind ; somewhat swollen, bearing two
pairs of furrows, more or less obscure, which die out towards the
axis of the glabella. Cheeks about equal in width to the glabella,
and bearing a groove which runs directly forward from the posterior
margin at about a quarter of its length from the glabella, and
meeting the glabella in its widest part. Anterior part of head-
shield not preserved.

The body consists of six flat segments, the axis being slightly
raised and rather more than a fifth of the width of the thorax.
Pleure straight and horizontal, grooved by a strong diagonal furrow
which divides them unequally. :

Pygidium rounded or subtriangular, with entire margin. Axis
conical, and bearing eight or nine rings which become small and
obscure anteriorly. There are six lateral lobes, each somewhat
fusiform in shape and grooved diagonally in a manner similar to

1 J. W. Salter, ¢ Brit. Organic Rem.’ Mem. Geol. Surv. dec. vii (1853) pl. vii.

Vol. 67.] AssOCIATED ROCKS OF NORTH-EAST MONTGOMBRYSHIRE. 451

that of the pleure. The lobes are separated by distinct furrows,
which broaden towards the margin of the tail,
_ Remarks.—tThe species is somewhat like Ampyw nudus,’ but
the shape and character of the tail distinguish it from that species.
It bears a rather close resemblance also to Dionide richardsoni*; buti
its broad shape, the narrow flattened tail, and the grooves in the
cheeks are all points of difference. I believe the form to be a new
species ; owing, however, to the imperfect state of the head, I have
hesitated to name it.

Horizon and locality.—Trilobite-Dingle Shales, Middle
House Dingle, Guilsfield. |

(2) Ostracoda. Re. a9 a .

Genus MEnaneLua, nov. Wis darth. wade
VA
Jonesella (pars) Ulrich, Journ. Cinc. Soc. Nat. Hist. vol. xi1i (1890-91) p. 121.

Carapace small, equivalve, moderately convex, subcircular, rather
flattened anteriorly ; hinge straight; valves with a small, faintly-
raised horseshoe ridge confined to the posterior half, enclosing a
small semicircular sulcus. Edges simple.

This genus is closely allied to Jonesella of Ulrich, and less
intimately to Bollia of Jones & Holl. In the latter genus the
horseshoe ridge is larger and more central, while the edges of the
valves are thickened. In Jonesella the loop is a well-developed
ridge, which is usually confined to the posterior half or two-thirds,
but it occupies a greater portion of the valve than it does in
Melanella. I have reproduced Ulrich’s figure of Jonesella crepidi-
forms for comparison (see fig. 9 c, p. 452). Jonesella obscura Ulrich
is most closely allied to the present form, and should be placed in
the new genus. Ulrich, in describing this species,* shows plainly
the need for a new genus here. He calls J. obscura ‘an incipient
Jonesella,’ and shows that it has characters which are allied both to
Bollia and to Ulrichia.

MELANELIA HEMIDIsctUs, gen. et sp. nov. (Figs. 9 a & 9, p. 452.)

Length =0°76 millimetre; height =0°65 mm.

Valves moderately convex, almost semicircular in outline. Hinge
straight and rather short, slightly rounded at the ends. MHorse-
shoe ridge low and obscure, entirely within the post-dorsal half,
enclosing a sulcus which contains a low tubercle. ‘The species
differs from Melanella (Jonesella) obscura in the more semicircular

1 KE. Forbes, ‘ Brit. Organic Rem.’ Mem. Geol. Surv. dec. ii (1849) pl. x.

* H.R. C. Reed, ‘ Lower Palxozoic Trilobites of the Girvan District, Ayr-
shire’ Monogr. Pal. Soc. (1903-1906) p. 26 & pl. iv, figs. 3-8.

3-T. R. Jones, ‘On some Devonian & Silurian Ostracoda from North
America’ Q. J. G.S. vol. xlvi (1890) pp. 540, 548 & pls. xx—xxi.

* ‘Geology of Minnesota’ Geol. Nat. Hist. Surv. Minn. vol. iii, pt. 2 (1897)
pp. 667, 668.

452 MR. A. WADE ON THE LLANDOVERY AND [Aug. 1911,

shape of the valve, in the fact that the dorsal margins of the loop
are not so prominent, and in the presence of a slight tubercle
within the sulcus enclosed by the loop. I have figured Ulrich’s
species for comparison. :

Fig. 9.—Melanella hemidiscus gen. et sp. nov. (a & 6) and
Jonesella crepidiformis Ulrich (c).

a 6 G

[Magnification = about 15 diameters. |
Horizon and locality.—Black shales of Gwern-y-brain.

In addition to the species just described, several others occur in
the Gwern-y-brain Shales, which are new to British geology. The.
following brief notes will serve to record their chief characters :—

PRIMITIELLA UNIcORNIS Ulrich. (Pl. XXXVI, figs. 4 & 5.)

This species has already been described by the late Prof. Jones
from specimens obtained by Bickerton Morgan from the Gwern-y-
brain Shales. There are, however, one or two distinct varieties
present which are referable to this form.

Var. 1 differs from the type-form in having a tubercle placed
centrally, as well as a sulcus in the anterior fourth of the hinge-
line.” (See PL XXXVI, fig. 4.)

Var. 2 is distinctly punctate, with one large pore placed in a
central position anteriorly with a slight sulcus behind it. (See
Pl. XXXVI, fig. 5. Unfortunately the punctation does not show
distinctly enough in the figures reproduced in this Plate.)

PRIMITIA ULRICHI Jones.

This species corresponds in shape and size with the late Prof.
Jones’s specimen, but differs in having a slight sulcus about half-
way along the hinge-line.

PrRiMItTIA TUMIDULA Ulrich.

This specimen is a trifle larger than the species described by
Ulrich, otherwise it possesses similar characters,

Crenoponina cf. ci1nIatTa Emmons. (Pl. XXXVI, fig. 6.)

The shales provided both a typical specimen and a distinct
variety, which is smaller and differs in the anterior ridge being
small and separated from the central ridge. It may almost be
considered a new species.

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 403

Boitra Lata (Vanuxem & Hall).

This species differs only from the type in the horseshoe ridge
becoming less marked in the ventral region.

KRAUSELLA ARCUATA Ulrich.

Bairdia (Krausella) anticostensis of Jones closely resembles this
specimen, but its more acute shape allies it more nearly to Ulrich’s
species.

(3) Gasteropoda.
CYcLONEMA DONALDI, sp. nov. (PI. XXXVI, figs. 7-9.)

Shell subconical. Height and width approximately equal, about
12 millimetres. Apical angle=about 60°. A vertical plane through
the apex of the shell would cut it into two unsymmetrical parts, one
side sloping at a greater angle than the other. Whorls, four well
preserved, with a rudimentary fifth; nucleus absent. The whorls
are convex, with a slight concavity towards the top of each whorl,
where it meets the succeeding one. This line of junction is slightly
oblique to the horizontal. Revolving ridges or strie absent, but
the whorls are marked with fairly strong, oblique, transverse lines
about 1 mm. apart, parallel to the margin of the aperture.

This species is closely allied to Cyclonema subleve of Ulrich,’ but
the revolving lines present in that species are absent here. The
oblique ridges, too, are more strongly developed; while the slight
concavity in the upper part of each whorl also serves to distinguish
it. Moreover, the angle of the spire is rather more obtuse.

Trochus constrictus of M‘Coy* is very like this species in most
respects. It is, however, a larger and more symmetrical form. In
M‘Coy’s species the whorls are nearly horizontal, so that each whorl
is almost centrally placed with regard to the succeeding one.

On these grounds I venture to name the species after Miss Jane
Donald (Mrs. G. B. Longstaff), who has done so much research-work
upon the Paleozoic gasteropoda.

Horizon and locality.—Gaerfawr Grits, Old Quarry, Moel-
y-garth Wood.

BELLEROPHON (PROTOWARTHIA) PORTLOCKI, sp. nov. (PI. XXXVI,
figs. 10-12.)

Height =27 millimetres; width at mouth =20 mm.; width
at the opposite extremity =9 mm.; breadth =14 mm.

Shell elongate, elliptical in section about the plane which cuts it
symmetrically. Closely coiled, leaving practically no umbilicus.
The whorls expand rapidly, until at maturity a fairly abrupt ex-
pansion gives rise to a wide aperture, which appears to have been

1 ‘Geology of Minnesota’ Geol. Nat. Hist. Surv. Minn. vol. ili, pt. 2 (1897)
p. 1062 & pl. lxxviii, figs. 48-49.
2 «British Paleozoic Fossils’ 1855, p. 296 & pl. i &, fig. 41.

454 MR, A. WADE ON THE LLANDOVERY AND [Aug. I91T,

somewhat bilobate. Slit-band absent. This species might easily
be mistaken for Bellerophon (Protowarthia) bilobatus of Sowerby.
It differs, however, in the rapid expansion of the aperture, a feature
which allies this form to the genus. Salpingostoma of Reemer. But
the absence of a slit-band and the slight umbilicus place it in the
subgenus Protowarthia. It is most closely allied to Bellerophon
elongatus of Portlock. The nature of the aperture is a distin-
guishing feature, while the species is smaller than that of Portlock.
It is, however, so near to it that I have ventured to name the
new species after him.

Horizon and locality.—Gaerfawr Grits, New Quarry,
Gwern-y-brain. '

CarinaRopsis acura Ulrich & Scofield. (Pl. XXXVI, figs. 18-15.)

‘Geology of Minnesota ’ Geol. Nat. Hist. Surv. Min. vol. iii, pt. 2 (1897) p. 928,
& pl. Ixii, figs. 6-9.

This shell appears to be new to British paleontology. It is
fairly common in the Pwll-y-glo Beds, and agrees in detail with
the species described by the authors from the Ordovician shales of
Minnesota. ‘Two specimens are figured—the first a mature form,
the second a young variety.

Horizon and locality.—Pwll-y-glo Beds, Second Old Quarry,
Pwll-y-glo.

EccyLioMPHALvs conticguus Ulr., var. camBRENSIS nov. (Pl. XXXVI,
fig. 16.)

The shell is 15 millimetres high and 10 mm. broad. It consists
of three rapidly enlarging contiguous whorls, coiled so as to have
a deep umbilicus. The outer whorl embraces the inner one, so
that only a small portion of the inner whorl is seen. The lower
lip of the aperture curves downwards on to the inner whorl.

The surface is covered with very fine and regular striz, parallel
with the edge of the aperture. The species is very similar in size
and in general characters to Ulrich’s Eccyliomphalus contiguus.? It
differs, however, in having a narrower umbilicus and in being more
finely and more regularly marked. It is, nevertheless, so near to
Ulrich’s species that I consider it to be simply a variety, such as:
one would expect to occur over the wide geographical area which
separates the localities from which the specimens have been
obtained.

Horizon and locality.—Very common in the black showed
of Gwern-y-brain.

1 “Report on the Geology of Londonderry, &e.’ 1843, p. 397 & pl. xxix,
figs. 4a-40.

2 «Geology of Minnesota’ Geol. Nat. Hist. Surv. Min. nly iii, jets ae
p. 1037 & pl. lxxiv, figs. 48-52.

<=” -_y

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMBRYSHIRE. 409

Crrrotites parvus Ulrich, var. cartnarus nov. (Pl. XXXVI,
fig. 17.)

This pretty little fossil corresponds closely with Ulrich’s species.’
It differs, however, in having a distinct and well-defined keel,
which is absent in the type-specimen. ‘This is so well-marked a
feature that I have named the Welsh variety carinatus.

Horizon and locality.—Trilobite-Dingle Shales, Penbryn
Dingle.

(4) Brachiopoda (Inarticulata).

LINGULA OBTUSIFORMIS, sp. nov. (Pl. XXXVI, figs. 18 & 19.)

The two specimens figured are respectively 7 and 4°8 millimetres
long, and 5 and 3°6 mm. broad.

Shell almost oval in shape, narrowing slightly at the beak.
Almost flat, very slightly raised on the umbones. Beak not placed
at the extreme posterior border as in most species of Lingula, but
completely surrounded by the margin of the shell. The posterior
portion of the valve is bisected by a strong median septum. The
surface of the shell is covered with strong concentric ridges, parallel
with the margin and sometimes showing stronger lines of growth.
In addition to the concentric ridges, radial striz also occur.

This species corresponds most closely with L. obtusa of Hall’;
but the ribbings are much more pronounced, and the median
septum is not seen in that species. It has also apparently some
affinity to L. coburgensis of Billings.* The characters of the shell
seem to be sufficiently distinct to warrant the formation of a new
species ; and, because of the close relationship to L. obtusa, I propose
to call this species Lingula obtusiformis.

Horizon and locality.—Gwern-y-brain Shales, Guilsfield.

(5) Corals.

StREPTELASMA (?) aff. BRevE Ulrich. (PI. XXXVI, figs. 20 & 21.)

Height = 18 millimetres; width across cup=26 mm. Corallum
free, simple, conical, slightly curved, and expanding very rapidly.
Width greater than height. Surface marked with strong annulations
and rather pronounced vertical ribs. Calyx deeply concave, extend-
ing to about athird of the height from the rim of the corallum.
Septa large and small: total number of septa=about 72. The septa
reach to the centre of the calyx, but the internal structure is
not seen. The species is very like Streptelasma breve Ulrich,* but
is larger, straighter, and possesses a more shallow calyx.

Horizon and locality.—Powis-Castle Beds, Powis Park.

1 «Geology of Minnesota’ Geol. Nat. Hist. Sury. Minn. vol. iii, pt. 2 (1897)
p. 864 & pl. lxii, figs. 45-47.

2 «Palxontology of New York’ vol. i (1847) p. 98 & pl. xxx, figs. 7 a-7 c.

3 «Paleozoic Fossils’ Geol. Surv. Canada, vol. i (1861-65) p. 50, fig.354;
‘Geology:of Canada’ Rep. Progr. Geol. Sury. Can. 1863, p. 161 & fig. 132. i

4 «Geology of Minnesota’ Geol. Nat, Hist. Surv. Minn. vol. iil, pt. i (1895)
pp. 92 & 98, figs. 7 a-7d.

cre en RR _

456 - MR. A. WADE ON THE LLANDOVERY AND [Aug. 1911,

(6) Graptolites.

The graptolites are mostly forms which have been described fully
by Miss Elles and Miss Wood (Mrs. Shakespear), either in the
works already mentioned [9] & [10], or in their monograph on the
British Graptolites still in progress.

Figs. 10 a and 106, however, seem to be slight variations upon
Diplograptus (Amplexograptus) pereacavatus Lapw. The enlarged
figures show the extraordinary spiny and irregular nature of the
thece. This is commonly seen in the species from Trelydan and
Sale Dingles.

Fig. 11 represents an interesting young specimen of Monograptus
vulgaris from the Tyn-y-llwyn outlier. The chief point of interest
is In connexion with the sicula. The early stages of the grapto-

lite suggest in a surprising manner Corynoides calicularis of
Nicholson. .

Fig. 10.—Amplexograptus per- Fig. 11.—Young form of
excavatus Lapw., magnified 5 Monograptus vulgaris,
diameters. magnified 5 diameters.

a b

[Both specimens are from Trelydan [The specimen is from
main dingle, about 100 yards down. | Lyn-y-llwyn. |

In concluding the notes on the paleontology of the area, I should
like to mention a feature which this study has indicated. Where-
ever shales and deep-water deposits occur in the sequence, there
is a remarkable influx of types which are common to the similar

1 ‘Monogr. Brit. Graptolitide ’ London, 1872, p. 132, fig. 74.

\}- ——.Ceunant —

Nh

== Mille

SSeS se Se
i =Miridle Flonse

Brickworl
& Quarry

=i, EXPLANATION:—

stom
cs q ~—
7 QX2 | Alluvium
{ WU Yr Allt Group
; (Ludlow)
= Salopian
Wenlock Shales
frome with Limestone
TIMI] pecetmeton Shales
; (Tarannon)
| (soelsl°S] Powis Castle Beds, etc.
3] (Llandovery)

j Gwern=y=brain Shales ett;
4 = with Limestone 5 Ashgillian

: e] | Gaer=tawr Grits
ELE ‘J with Limestone

i iil Caradocian
; I Pwlii=y=glo Group

- if SS
WIN F==="| Trilobite Dingle Shales )} aes:
Se AH f° y fe iat (=Dicranograptus Shales)5 Glenkiln-Hartfell

Buttingtony
Hall

Valentian

hro’
oN

a
a ee Brookland) — —
eee -Hall— = 1 aN Ih sete
} SSS SS ae a ese (HH HY HH I Ve f di Dyke of Bostonite
iW ==)ene= Penbryn jas ses oN ;
iin os Tn 7h 35 Sao ORS
HN F Ln A tty Faults (broken line
1

} ———- where doubtiul)
H |

ea garth iy sy}
LEECH REL AZ
IS

AC

BANS)

ai

ad VAL
Samet | UI
E 19 ize

5°o= Dip (with aces)

50
Quarrie FA

ys NS =e x Axis of Anti¢line

oN Axis of Syncline

A\SU\ Contorted Strata

Lines of Section

Powis astle |

ic
Lrefnant

lc
ex

a
e

y
y
J f
y
ESET

OL)
el ~| |
oN
Geological Map |
OF THE ee =\
Neighbourhood of Welshpool. Beldnd//X—\
(Drift not shown) =
By Arthur Wade, B.Sc..F.GS. Ss
Ua
8Furlongs 4 0 Miles I Sas. 2 3

ne “op rota ated

RE

by es
V

pe ps Reo dun

5 ie Se ! i
i pp pede al SOR Ye os anaes) y ‘a Dheebas ee ae ab +i Tige

QuART. JOURN. GEOL. Soc. Voc. LXVII, PL. XXXIV.

[Bemrose Collo,

QUARRY-SECTION IN THE BUTTINGTON SHALES, SHOWING THE HIGH INCLINATION OF THE STRATA.

A. W., Photo.)

Quart. JourRN. GEOL. Soc. VoL. LXVII, PL. XXXV.

Fic. 1.—IG@NEOUS AND FELSPATHIC FRAGMENTS IN THE
Upper GAERFAWR GRITS.

A, W., Photo.) {Bemrose Collo.

QuarT. JOURN. GEOL, Soc. VoL. LXVII, PL. XXXVI.

= Sey
A. W., del. et photo. Bemrose Ltd., Collo., Derby,

UPPER ORDOVICIAN Ano LOWER SILURIAN FOSSILS
FROM NorRTH-EAsT MONTGOMERYSHIRE.

.
.

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 457

deposits of both Britain and America. The fossils of the grits and
the shallower-water types in general are more distinctively British.
This, of course, is a phenomenon which might have been expected.

The fossils described will be offered to the Museum of Practical
Geology, Jermyn Street ; while the remainder of the collection will
remain in the Geological Laboratories of the Imperial College of
Science & Technology.

Concluding Remarks.

In conclusion I desire to express my gratitude to Prof. Watts, at
whose suggestion I entered upon this work, and from whom I have
received much encouragement and advice. My sincere thanks are
also due to Prof. Lapworth, who kindly placed at my disposal much
of the material collected by the late Mr. Bickerton Morgan.

EXPLANATION OF PLATES XXXITII-XXXVI.
Puate XXXII.

Geological map of part of North-Eastern Montgomeryshire, on the scale
of an inch and a half to the mile, or 1 : 42,240.

Prats XXXIV.

Quarrv-section in the Buttington Shales, Buttington Brickworks, showing
the high inclination of the strata against the ‘diabase’ intrusion at Cefn
and the effect of soil-creep at the surface. (See p. 436.)

Puats XXXV.

Fig. ]. Grit-band in the caleareous beds of the Upper Gaerfawr Grits,
showing fragments of felspar and of fine-grained basic igneous rock.
Magnified 50 diameters. (See p. 428.)

2. The Welshpool Dyke, showing columnar structure in concentric layers.
(See p. 447.)

Pruate XXXVI.

Figs. 1 & 2. Trinucleus intermedius, sp. nov. Natural size. (See p. 449.)
Fig. 3. Dionide sp. Magnified 2 diameters. (See p. 430.)
4, Primitiella unicornis Ulrich, var. 1. Lett valve. Magni-
fied about 16 diameters. (See p. 452.)
5. Pr. unicornis, vay. 2. Right valve. Magnified about
16 diameters. (See p. 452.) mS
6. Ctenobolina ef. ciliata Emmons. Right valve. Magnified
about 16 diameters. (See p. 452.)
Figs. 7, 8, & 9. Cyclonema donaldi, sp. nov. Natural size. (See p. 453.)
Figs. 10, 11, & 12. Bellerophon (Protowarthia) portlocki, sp.nov. Natural size.
(See p. 453.)
13 & 14. Carinaropsis acuta Ulrich & Scofield. Adult. Natural size.
(See p. 454.)
Fig. 15. C. acuta. Young specimen. Natural size. (See p. 454.)
16. Eecyliomphalus contiguus Ulr., var. cambrensis, nov. Natural
size. (See p. 454.)
17. Cyrtolites parvus Ulv., var. carinatus, nov. Natural size.
(See p. 455.)
Figs. 18 & 19. Lingula obtusiformis, sp. nov. Natural size. (See p. 455.)
20 & 21. Streptelasma (?) aff. breve Ulr. Naturalsize. (See p. 455.)

Oo. J /G.S. No. 267. ZT

458 MR. A. WADE ON THE LLANDOVERY AND [Aug. 1911,

Discussion.

Mr. W. G. Frarnsipes congratulated the Author upon his lucid
exposition of the rock-succession and structure of a most fascin-
ating district, and upon the great advance of knowledge which
was represented by his results. He thought the evidence of the
continued instability of the Welshpool anticline during the Silu-
rian Period most important. It showed that the Welshpool district
was already unstable, even before depression had allowed Silurian
sediments to overlap on to the Longmynd and Carneddau anticlinal
districts, and that in later (Wenlock and Ludlow) times it had
followed rather accurately the up-and-down movements of those
neighbouring districts.

In regard to the Author’s correlation of his highest Ordovician
subdivision with the Ashgillian of Dr. Marr, the speaker was less
satisfied. The terms in which the Author had described the litho-
logical succession from the Trilobite-Dingle Group upwards might
well be used to describe the successive members of the Bala Group,
either in the region south of Bala Lake or in Western Carnaryon-
shire; but, in both those districts, the place of the black shales of
the Gwern-y-brain Group was taken by equally black shales
containing Diplograptus truncatus, a graptolite which marked a
horizon well below that at which the great Ashgillian Series was
supposed to begin. In the opinion of the speaker the Ashgillian
Series about Welshpool must be completely overstepped by the
sandy and conglomeratic beds of the Llandovery.

Mr. H. H. Tomas congratulated the Author, both on his choice
of ground, and on the results that he had achieved. He remarked
that the Trilobite-Dingle Beds, from the abundance of Amplexo-
graptus perexcavatus, represented a low horizon in the Dicrano-
graptus Shales, and should be succeeded by beds containing
abundant Mesograptus and species of the larger Diplograptids—
such as Orthograptus calcaratus var. vulgatus. He asked whether
the Author considered his Pwll-y-glo Beds to be the equivalents of
the higher portion of the Dicranograptus Shales, as developed in
other districts. With regard to the black shales above the Gaer-
fawr Beds, the speaker agreed with Mr. Fearnsides that there were
difficulties in the way of accepting them as belonging to the
Ashgillian. He also asked whether it were not possible for these
shales to belong to the zone of Pleurograptus linearis, and to repre-
sent similar shales which in South Wales and elsewhere were
characterized by Diplograptus truncatus, and occurred beneath the
Ashgillian.

He was much impressed by the striking manner in which the
undoubted Llandovery beds transgressed the older series, and also
by the way in which high zones of the Wenlock came to rest upon
rocks of Valentian age. Mr. Cantrill and the speaker had in South
Wales also noted that near Llandeilo a high zone of the Wenlock
characterized by Monograptus fleningi was only a little way above

Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONIGOMERYSHIRE. 409

beds yielding Pentamerus undatus. This would indicate an overstep
at about the same horizon as in the cases described by the Author.

The Presipent pointed out that the Author’s map, when com-
pared with that of the Geological Survey and with Murchison’s
work in the area, showed how much new work had been done by
the Author in this district. He recalled that the previous investi-
gator of the area was Mr. Bickerton Morgan, who unfortunately
died before he could complete his work. The district was interest-
ing as a link between the little-known region of South Wales on the
one hand, and that of Shropshire on the other. He did not recognize
any marked resemblance between the igneous rock described by
the Author, and the intrusive or interbedded rocks of the Breidden
Hills.

The Avruor said, in reply to Mr. Fearnsides, that the difficulty
raised with regard to the Black Shales of Gwern-y-brain seemed
to depend upon the identification of the graptolites. The horizon of
these shales was certainly higher than that suggested. The com-
bined palzontological evidence tended to confirm that view. It
Was quite possible that zones representative both of the Ashgillian
and of the Lower Valentian were present; but, since the beds
were very limited both in thickness and in distribution, and since
the overlying conglomerate formed the natural base of the Silurian
rocks over the rest of the area, the Author had considered the series
as one group, which he regarded as corresponding most closely
with the Ashgillian.

In reply to Mr. Thomas, he said that the Pwll-y-glo Beds con-
tained Orthograptus calcaratus and allied forms, and therefore could
be correlated very well with the zones of the Dicranograptus Shales
of South Wales mentioned by that speaker.

In reply to the President, the Author said that he had in mind
the diabases of the Breidden district, and although he did not claim
that the Welshpool-Dyke rock was exactly similar to those diabases,
it seemed possible that it was a local variation in which the ferro-
magnesian mineral was not well developed.

In conclusion, he thanked the Fellows present for their kind
reception of the paper.

cae ieee

cometh JGR Oiie
Wome Dae

Tana: ope bee piae

tt ros ix? ait Deaths
i ae ‘singe’

is

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‘ 1 gst vith

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10. Mr. E. 8. Cobbold on Trilobites from the Paradoxides Beds of Comley.
UP lates IRD DT KOK VB ye comcihe, nue Ge arn eeceaknte alee ee eaamee 282

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14. Mr. F. G. Collins on the Culm of the Exeter District. (Plate XXXII) ... 393

15. Mr. A. Wade on the Llandovery & Associated Rocks of North-Eastern
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Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONIGOMERYSHIRE. 459

beds yielding Pentamerus undatus. This would indicate an overstep
at about the same horizon as in the cases described by the Author.

The Presivent (Prof. Warts) pointed out that the Author’s map,
when compared with that of the Geological Survey and with
Murchison’s work in the area, showed how much new work had
been done by the Author in this district. He recalled that the
previous investigator of the area was Mr. Bickerton Morgan, who
unfortunately died before he could complete his work. The district
was interesting as a link between the little-known region of South
Wales on the one hand, and that of Shropshire on the other. He
did not recognize any marked resemblance between the igneous
rock described by the Author, and the intrusive or interbedded
rocks of the Breidden Hills.

The AvrHor said, in reply to Mr. Fearnsides, that the difficulty
raised with regard to the Black Shales of Gwern-y-brain seemed
to depend upon the identification of the graptolites. The horizon of
these shales was certainly higher than that suggested. The com-
bined paleontological evidence tended to confirm that view. It
was quite possible that zones representative both of the Ashgillian
and of the Lower Valentian were present; but, since the beds
were very limited both in thickness and in distribution, and since
the overlying conglomerate formed the natural base of the Silurian
rocks over the rest of the area, the Author had considered the series
as one group, which he regarded as corresponding most closely
with the Ashgillian.

In reply to Mr. Thomas, he said that the Pwll-y-glo Beds con
tained Orthograptus calcaratus and allied forms, and therefore could
be correlated very well with the zones of the Dicranograptus Shales
of South Wales mentioned by that speaker.

In reply to the President, the Author said that he had in mind
the diabases of the Breidden district, and although he did not claim
that the Welshpool-Dyke rock was exactly similar to those diabases,
it seemed possible that it was a local variation in which the ferro-
magnesian mineral was not well developed.

Tn conclusion, he thanked the Fellows present for their kind
reception of the paper.

Q.J.G.S. No. 268. 2

460 PROF. W.S. BOULTON ON A MONCHIQUITE INTRUSION [ Nov. rorz,

16. On a Moncuievire Intrusion in the OLp Rep SanpstonE of
Monmovrusnire. By Prof. Wit11am S. Bovunron, B.Sc.,
Assoc. R.C.8., F.G.8. (Read June 14th, 1911.)

[Pirate XXXVII—Microscore-Secrions. |

CoNnTENTS.
Page
i Positionand Mield=Relations “"....225......-.06s.e- ee 460
IT. Field-Characters and Relations to the Contact-Rocks ......... 461
Itt. Petropraphical Details - 6.2... .3se0i2- ot senn2 nee eens ee 464
DY Chemical Composition 1. ..0.22he.se- ose doe eee 470
iV. The Olivine-Augite-Rock Inclusions ..2.0...::..-..secn see eee ay
Vil. Atiinities with other Rocks |......6.2.0 oaks ee 474
VEL SMM AY 52d tie oe de es -ceras a delens Sooo eae teee donee tea eee 475

I. Posrtrion anp Fretp-RELATIONS.

THE igneous intrusion here described, and hitherto unrecorded, is
situated in Monmouthshire in lat. 51° 40’ N., long. 2° 49’ 30” W.
Following the main road from Chepstow to Usk for about 74 miles,
and then branching off southwards for another mile and a half, we
come to a place which is marked on the 6-inch Ordnance map
of the district as the ‘Great House’; and about 250 yards north
of it, the rocks in question are exposed. Some 70 yards north-
west of the carriage-drive leading to the house (where [I first
noticed the rock which was being used to ‘metal’ the drive), a small
quarry has been excavated in the rising ground. It is in this
quarry that the main exposure of the monchiquite is seen, and
from which most of the material described in this paper was
obtained. (Fig. 1, p. 461.)

The quarry measures about 20 by 25 yards and is some 20 feet
deep. A few yards west of it is a small, shallow opening, from
which the igneous rock has evidently been taken, and some
of it may still be seen i situ cropping out through the grass.
Still farther west, over the fence, a similar hollow is seen, and: a
little north of it is an old quarry measuring 20 yards across and
of considerable depth, with a pool at the bottom and the sides
overgrown with bushes and long grass. In this old disused quarry
no rock is visible in position; but large, loose lumps of the
monchiquite and slabs of sandstone are lying about.

The monchiquite is intrusive in the Old Red Sandstone, which

covers so large an area in this part of Monmouthshire, though the

exact stratigraphical position is uncertain. From general traverses
through the district, it appears to lie near the base of the upper
division of the system or Brownstones, made up of red sandstones
and conglomerates, with subordinate bands of red marl.

Vol. 67.] IN THE OLD RED SANDSTONE OF MONMOUTHSHIRE. 461

Fig. 1.— Map of the neighbourhood of the Great House, t]
Golden Hill (Monmouthshire).

gtow

YX go Che

*\(Monchiquite \i a
rm Ps Fragments) &
N85 WH niouite’ Fi

~ pee aut i ny >

Ouarry% : fff a i)

(Monchiquite)ss, S
NN

eae
Dine

I

Avie

Feet 0 it 29039 0 ec as ae - Contour-lines

Il. Frevp-Caaracrers anp Renations To THE Conract-Rocks.

The rock in the recently opened quarry * is much weathered to a
buff or rusty colour for a depth of 6 to 10 feet, and along the joints ;
but where unweathered it is dark grey, nearly black, compact
and glassy looking, and extremely hard and tough. It contains.
remarkably big phenocrysts of augite and biotite, the former
measuring up to d or 6 inches in length; and when much corroded,
as is often the case, they form spherical or ovoid masses, of a black
or dark greenish colour. The biotite-plates up to 2 inches across
lie on the face of the quarry, or project conspicuously from the rock.

In the ground-mass, white, green, and pink patches, some small
and round, others large and irregular, are evidently filled with
secondary products. Here and there are patches of rounded or
oval shape, up to 8 or 9 inches across, quite different in appearance

1 I was told by a man on the estate that it was opened about ten years ago.

2x2

462 PROF, W.8. BOULTON ON A MONCHIQUITE INTRUSION [ Nov. 1911,

from the augites. They are made up of a confused aggregate uf
a brown or green, bronzy looking mineral, with a marked mica-like
cleavage; together with a purplish-grey substance that effervesces
under acid ; small, irregular, black crystalline grains of augite; and
much green and yellow colouring-matter. As will be shown later,
these are included lumps of olivine-augite rock, distinct from, but
related to, the monchiquite in which they occur.

A very noticeable feature is the large amount of the country-
rock that has been caught up by the intruded magma. Chips of
sandstone and bigger lumps, upwards of 2 feet across, both of
sandstones and marl, are irregularly distributed—in one part of the
mass so thickly as to suggest a tuff or agglomerate; and on the
weathered surface they give to the rock a very rough, rusty looking
appearance.

The included lumps of marl are generally well rounded, and
have been converted into a dark porcellanite with a sharp flinty
fracture; while the subangular lumps of sandstone have a bleached
appearance or yellowish-brown colour, and break with a lustrous
fracture. Much secondary calcite, silica, and chloritic matter occur
in the vicinity of these xenoliths, the silica often assuming’ an agate-
like disposition.

On the northern face of the quarry, particularly in the central
part, the rock shows a pronounced spheroidal jointing, with the
characteristic weathering into concentric shells.

The principal linear joints run in two directions, one set nearly
due north and south, and the other north-west and south-east.
Iron-stained silica, with some calcite and chlorite, and a little
earthy manganese oxide and copper carbonate fill most of the joints
and eracks.

The nature of the intrusion and its relation to the
surrounding rocks are difficult to determine. Only at one place
‘is it possible to see a junction of the igneous rock and the sandstones :
mamely, at the eastern side of the quarry. Here the invading rock
‘cuts obliquely across the sandstones, which are dipping at this
‘spot at about 30° north-eastwards,’ so that the line of junction is
roughly in an east-north-easterly direction.

The monchiquite, which is exposed at the centre of the quarry to
-a depth of some 6 feet below the level of the sandstone, abuts against
the sandstone with a nearly vertical junction-surface, running
with the dip. Thejunction then coincides with the bedding in a sill-
like way, for about 12 or 15 yards to the end of the quarry. For
some 3 or 4 feet from the junction the igneous rock assumes a less
massive appearance; it has a rough, scoriaceous, and finely nodular
texture with a coarse pseudo-lamination, the joint-planes lying
nearly vertical. In this shaly-looking igneous rock he rounded
lumps of burnt marl, measuring from 6 inches to 3 feet across.
‘They are brown and yellow on the outer burnt border, but dark

1 The general dip hereabouts is 10° east-north-eastwards.

Vol. 67.] IN THE OLD RED SANDSTONE OF MONMOUTHSHIRE, 463

red, nearly black, inside, and weather into beautifully-regular
concentric shells. Some have an internal, finely-nodular structure,
breaking up like a perlitic pitchstone, doubtless due to shrinkage
after having been heated up in the magma.
ov 1
Fig. 2.—Fine-grained Old Red ae ce HAs oe
Sandstone at the contact with appearance of the sandstone
the monchiquite, showing P’- — onthe floor of the quarry, close
tial fusion. (Natural size.) to the contact. On a fractured
or polished surface of the rock,
deep yellow areas, not unlike
the spherulitic patches of an
obsidian or felsite, lie on a dark
purplish-red ground. A thin
slice further shows that, in the
yellow areas, the rock is thickly
covered with yellow oxide of
[Dotted areas are dark purple sand- ron and the quartz-grains are
stone. Light areas are deeply partly or wholly corroded;
stained with yellow limonite,and while in the purple areas the
the quartz-grains are in part or sandstone is practically un-
wholly corroded. | ‘
altered, except for strings and

occasional patches of magnetite.

An examination of this contact, together with the disposition of
the included fragments of sandstone at the western end of the
quarry, suggests that the magma forced its way upwards, or perhaps
obliquely upwards from the north-west, and then ran for some
distance eastwards more or less with the bedding of the sandstones.
It may then have passed upwards into strata since removed by
denudation.

It will be gathered from the foregoing observations that it is
not possible to define positively the boundary-walls of the intrusion,
except on this eastern side; and here the junction is irregular. A
reference to the sketch-map (fig. 1, p. 461) shows the small openings
immediately to the west of the quarry, in one of which the igneous
rock is exposed; and the. old, overgrown quarry, where loose blocks
of the monchiquite have been left.’ The old quarry and plantation,
200 yards south-east of the recently worked quarry, shows no trace
of igneous rock; it is only about 8 to 10 feet deep, and was
apparently opened up in the sandstones. Thus we may take it as
practically certain that the monchiquite crops out for a distance of
about 300 feet in a north-north-westerly direction, and for about
200 feet in a direction at right angles to that.

All these openings where the monchiquite is exposed lie on a
rounded crest, which, beginning abruptly near the eastern quarry,
runs for nearly half a mile in a north-westerly direction across Golden
Hill, The trend of the intrusion may be in this north-westerly

1 No record of the working of this quarry could be obtained.

464 PROF. W. 8S. BOULTON ON A MONCHIQUITE INTRUSION [ Noy. 1911,

direction, and it may be a dyke of considerable width, which ends
abruptly at the south-eastern end where the quarry has been lately
worked; and, after for a time traversing the sandstones roughly
parallel with the bedding, the magma may have passed upwards
into strata now removed. No trace of the igneous rock, however,
either in outcrop or in surface-fragments, could be seen along this
crest, west of the old quarry already mentioned.

If the junction of the monchiquite and sandstone at the eastern
end of the recent quarry is to be regarded as one of the walls of
a dyke, then the dyke would trend oie epoveceegpwands which is
the direction of the Bartestree dyke, near Hereford (mentioned on
p. 474). Butif so, it would be of great thickness, between 200
and 300 feet; and moreover, the form of the ground, which is
probably determined to a great extent by the very hard igneous
rock, is against the dyke having this direction.

The plentiful inclusion of xenoliths of the country-rock is not
inconsistent with the view that the monchiquite is a dyke or a sill’;
but, having regard to the shape of the known outcrop, it seems not
unreasonable to conclude that we have here a volcanic plug or
bysmalith * with an irregular sill-like extension in an easterly
direction.

The available evidence, however, is by no means conclusive, and
the exact nature of the intrusion must be regarded for the present
as doubtful.

ILI. PrerroeRarurcaL Deratits.

Owing to the extent to which the rock has been weathered, and
to the fact that the quarry is not being worked at the present time,
big fresh lumps are difficult to obtain. Then, too, the included
Old-Red-Sandstone fragments are very plentiful in places; and, as
will be shown later, the monchiquite has an abnormal development
of carbonate and other secondary products in their vicinity.

Where the rock is coarsely porphyritic, as in the central parts of
the quarry, the large augite and biotite-crystals arrest attention.

Augite.—Perhaps the most striking feature of the rock is the
unusual development of the augite-phenocrysts. An individual
crystal was measured, having a length of 6 inches and breadth
of 3 inches, while prisms 3 or 4 inches long are quite common.®
Occasionally they have their original crystalline form in part well
defined, but usually the crystals have suffered much corrosion, and
many are quite spherical or ovoid in shape with no trace of their
original form, and in not a few cases they are deeply embayed by
the matrix, or almost entirely resorbed.

' See A. Harker, ‘The Tertiary Igneous Rocks of Skye’ Mem. Geol. Surv.
1904, chap. xx.

2 J, P. Iddings, ‘Igneous Rocks’ vol. i (1909) p. 316.

3 No evidence is forthcoming that these large augite-phenocrysts are aggre-
gates, producing a glomeroporphyritic structure : in all cases they
appear to be single crystals. They are, again, easily distinguished i in the field,
and under the microscope, from the xenoliths of picrite described on p. 471.

Vol. 67.] IN THE OLD RED SANDSTONE OF MONMOUTHSHIRE. 465

The mineral is typically black, sometimes greenish, with a dull
pitchy lustre and conchoidal fracture. The crystals that have
suffered corrosion to the greatest extent seem to be: those which
exhibit a specially dull lustre, while smaller ones have the more
_ usual augitic lustre.

It is much cracked, with limonite, chlorite, and secondary car-
bonate along the cracks. This strong tendency to crack makes it
practically impossible to break off specimens of the rock with very
big augite-phenocrysts entire. The crystals that have been much
corroded break away from the enveloping rock very readily,
evidently because the zone of fused and recrystallized augite (see
below) that surrounds the inner core makes a weak contact with
the matrix.

Seen in thin section the mineral is pale green, nearly colour-
less, occasionally a very pale pinkish-brown. In thicker sections
the colour is olive-green with slight pleochroism, the colours varying
from pale olive-green to brownish green. Besides showing the usual
prismatic partings, the mineral is much cracked, a yellowish-green
substance filling most of the cracks. Small rounded crystals of
altered olivine sometimes occur peecilitically ; but, apart from these,
and rods and flakes of hematite, the crystals show remarkably few
inclusions. No eases of twinning were met with.

It is probably a chrome-diopside, a variety of augite common
in rocks of this class. Generally, the borders show an outer zone
of resorbed augite, with a faint granular polarization; and, in many
instances, this border has been supplemented by an outer zone of
fresh augite that crystallized out from the magma immediately after
the corrosion of the phenocryst. This outermost zone is purplish
brown, appreciably pleochroic, and quite distinct in colour from
the original crystal. It is generally made up of minute stout
prisms, oriented with the principal axis of the phenocryst, so that
they all extinguish together, and uniformly with the original inner
core. (See: EE RASOV LE: fie) 1.)

Biotite.—Phenoerysts of biotite measuring as much as 2 inches
across are plentiful in some parts of the rock, and they sometimes
exhibit a parallel arrangement. They are in six-sided plates, but
usually the angles have been worn off by corrosion, so that they are
circular or oval.

By transmitted light they show a deep colour, with strong
pleochroism, the colour varying from yellow to reddish brown.
Examples can be noted where the crystal is deeply embayed by the
matrix, or again, where the crystal has been almost entirely eaten
up by the magma. Many of the crystals are bent and frayed out
at the edges, indicating violent movement and friction since their
formation.

Olivine.—Idiomorphic olivine-crystals, now entirely replaced
by serpentine, carbonates, etc., are corroded in much the same
way as the augite and biotite. It is probable, however, that some

466 PROF. W. 8. BOULTON ON A MONCHIQUITE INTRUSION | Novy. 1911,

of these corroded olivine-phenocrysts represent portions of the
plutonic xenoliths or ‘nodules’ which contain abundant olivine
(see p. 471).

The ground-mass enclosing these large phenocrysts contains
smaller porphyritic crystals of a second generation, including augite
and olivine, with occasional biotite, together with chromite and
rounded quartz-crystals, all set in a fine matrix which, under a
high power, resolves itself into analcite, embedded in which are
minute prisms of augite, plentiful octahedra of iron-ore, scales of
biotite and minute needles of apatite; while secondary products,
such as carbonates, idiomorphie analcite and other zeolites, chlorite,
hematite, and limonite are locally abundant, especially in the ocelli
and steam-cavities.

The porphyritic augites of the second generation, ranging
in length from 1 mm. down to the minute prisms of the ground-
mass, are well-formed, idiomorphic or sub-idiomorphic crystals, with
their angles perfectly sharp, and presenting the usual octagonal
and prismatic sections. The colour is purplish brown, with slight
pleochroism. Twinning israre. Purplish-brown crystals can be seen
with a nucleus of nearly colourless and partly-decomposed augite,
that doubtless represents the last remnant of the resorbed larger
phenocryst, on which the later augite has crystallized out in optical
continuity. It sometimes surrounds altered olivine, and very often
encloses crystals of biotite. Crystals occur with the centre pale in
colour and decomposed, surrounded by brown augite enclosing in a
, zonal manner numerous flakes of biotite.

Olivine of the second generation occurs in small idio-
morphic crystals (averaging 0°3 mm. in length), showing the
typical bipyramidal forms and cleayvage-cracks, but now entirely
represented by pseudomorphs of serpentine, iron-oxide, calcite, and
colourless zeolites.

The chromite or picotite varies in colour from deep reddish-
brown to brownish-yellow. It is usually in rounded crystals where
embedded in the matrix, their outlines being often emphasized by
broad, irregular, black borders of iron-ore.

The biotite closely resembles the earlier phenocrysts.

The quartz-grains are perfectly clear, except for the usual
minute, linear inclusions. They invariably show rounded outlines,
and are often considerably embayed by the ground-mass, with
a yellow or dark corrosion-border of fine granular substance sur-
rounding them (fig. 3 D, p. 467). In these characters they resemble
the quartz-inclusions or xenocrysts in other well-known basic
lamprophyres that have been described.’

The ground-mass under alow power is typically brown or
dark grey, plentifully dusted over with minute magnetite-grains.
But a high power reveals a very interesting structure, which throws
considerable light on the composition and affinities of the rock.

1 See A. Harker, Geol. Mag. dee. iii, vol. ix (1892) pp. 199-206 & 485-88.

Minute augite-prisms (of the third generation) with .
an average length of 0°05 mm. and breadth of 0°01 mm., nearly |
colourless, or of a pale greyish-purple or purplish-brown, and
showing longitudinal striation and faint cross-parting, are abundant.
Minute scales and plates of deep reddish-brown biotite often |
cling to the octahedra of iron-ore; and, filling up the spaces between
all these crystals, is a colourless or pale yellowish-grey or cloudy

.
Vol. 67.] IN THE OLD RED SANDSTONE OF MONMOUTHSHIRE. 467
substance, usually isotropic, but in places faintly birefringent with |

we 45
Fas

“ae

.
=<
vow

OK YA eG Sepa Lee \
Zit X LEN N Ss x Gigli ty Zn Sa A eM SAY i
Aas Se aa Pee SS = Se 2S Ke See SREY iy
4 POS BB - n ; a3) Te rar ,

Rees banal A ARES
re ef I fie), S peony |

SNe at Aa Nh, i ere i {

a we ff Sak AS: *
< ONS 2, Ii }

: x we
2 ;

Pate 1

° ree a ~ ;

5 es ik load iP
eSB. NL )
oe = eras? Ws L 4 | i}
Pe, = - a. by

~ ° '

[A=Analcite ground-mass, enclosing augite-prisms, apatite-needles, iron-ore, ie
and biotite. Towards the centre is a clearer space occupied by allotrio-
morphic analcite. 240 diameters. I }

B= Part of ocellus or steam-cavity, with sub-idiomorphic analcite, carbonate- ii
rhombs, and pale-green chlorite. x 240 diameters.

C=Decomposed augite-phenocryst, overgrown by augite-prisms. X 100 dia- lit]
meters. ie

D=Corroded quartz, together with olivine--and augite-crystals, in a monchi- }
quite ground-mass. X 40 diameters. | ,

pale neutral tints, and enclosing very minute needles of apatite. F
Its low refractive index, absence of colour, and isotropic character
suggest the mineral analcite, probably as a primary constituent, r
and evidence will shortly appear which strengthens this view |
(fig. 3 A, above).

468 PROF. W.S. BOULTON ON A MONCHIQUITE INTRUSION [ Noy. 1911,

A close search has failed to reveal any undoubted nepheline in
this ground-mass, but a fibrous, colourless, faintly-birefringent
zeolite, generally occurring in radial aggregates, and possessing a
low refraction, is probably the mineral natrolite, and may
possibly result from the decomposition of nepheline.

Ocellar spaces are frequently present, some quite small,
circular or elongated, with a parallel arrangement, doubtless repre-
senting original vesicles. Others are much bigger and more
irregular, suggestive of drusy cavities. ‘They are now filled with
pale-green chloritic matter; carbonates, often in beautifully
sharp rhombs with marked zonal structure; and perfectly clear
and colourless, idiomorphic or sub-idiomorphic and isotropic crystals
of secondary’ analcite (fig. 3B, p. 467).

Very minute, colourless or yellowish needles in feathery bunches
can also be made out, which usually polarize in bright tints.
These have proved too small for exact determination; they may be
muscovite or a mineral of the zeolite group.

Many of the spaces show a zonal arrangement, most frequently
with the pale-green chloritic substance occupying the centre of the
space and enclosing the carbonate rhombs; while the analcite-
erystals and the fibrous substance line the walls of the cavity
(fig. 3 B).

Some, again, have very indefinite outlines. They are merely
clearer spaces merging gradually into the surrounding ground-
mass. In such cases the clear space is occupied by allotriomorphic
analcite, and perhaps some carbonate and chlorite, while small
biotite-needles and augite-prisms with octahedra of magnetite range
themselves peripherally, projecting some distance into the clear
space (fig. 3 A).

The small ocelli pass by gradual stages into the larger pale pink
and white patches so noticeable in the hand-specimen, including
those which have banded agate-like or mammillated structure, and
where the infilling material is often iron-stained chalcedonic silica.

Some of the rock-sections reveal special points of interest.
Slide M 401 may be taken as an example (Pl. XX XVII, fig. 4).
It shows a small xenolith of fine-grained sandstone about half an
inch across, and surrounding it are numerous glassy fragments of
the igneous rock, showing a striking resemblance to palagonite-tuff.
The lapilli consist of the usual brown or yellowish-red basic glass,
enclosing small, perfectly spherical vesicles, now occupied by zeolites ;
while minute prisms of augite, olivine, and grains of, quartz are also
embedded in this glass. These fragments are set in a pale-grey or
colourless matrix made up of abundant rhombs of carbonate,
zeolites, and small fragments of sandstone.

The glassy character of these lapilli is doubtless to be explained

_ 7 The term secondary is here used without implying any considerable
interval between the formation of the analcite of the ground-mass and that of
the ocelli.

Vol.67.] IN THE OLD RED SANDSTONE OF MONMOUTHSHIRE. 469

by the rapid cooling of the magma, separated by the explosive
violence of the intrusion into small fragments, mixed contusedly
with cold chips of the adjacent sandstone.’ It is clear that the
fragmental character of the rock, both igneous and enclosed sedi-
mentary, testifies to the violence of the intrusion; but an added
interest is the significant difference between this glassy variety of
the magma and the usual (analcite) matrix, already described. In
other parts of the rock, small areas of glass with a very dark-brown
colour by transmitted light, can be made out. But, in every case
noted, the glassy patch surrounds or partly fringes a xenolith,
and is sharply separated off from the normal analcite-matrix
(Pl. XX XVII, fig. 5); or, if the glass occurs in somewhat larger
patches, it is invariably filled with innumerable small xenoliths.
The fact that we have, side by side as it were, the brown and yellow
basic glass and the colourless isotropic substance which ordinarily
plays the part of ground-mass in this rock, affords additional
evidence that this colourless substance is not glass, but analcite.?

As to whether the analcite of the ground-mass is primary, that
is, pyrogenetic, it is to be observed that, unlike some other rocks of
this class containing analcite, the constituents of this Monmouth-
shire monchiquite are not all of them fresh; the olivine in particular
is decomposed, and there is much secondary carbonate in the rock
(see Analysis I, p.470). On the other hand, the boundary between
the analcite and the locally-developed glass described above is
invariably a sharp one, not in the least suggestive of the conversion
of glass into analcite; and, moreover, the mineral of the ground-
mass is interstitial and without crystal-outlines, unlike'the secondary
analeite of the ocelli. Having regard to these points and to the
analogy of other analcite-bearing rocks where the mineral plays
the part of ground-mass as in this rock, and where the other
minerals are quite fresh, it seems highly probable that the analcite
here is primary.

The magma was apparently very hydrous, and crystallized under
pressure and somewhat rapidly, after being violently intruded
in a dyke-like or plug-like form into the comparatively cold sur-
rounding rocks. Analcite was formed as a sparse ground-mass
between the already consolidated minerals, showing here and
there in more conspicuous patches, comparatively free from ferro-
magnesian minerals and iron-ore (‘analcite-phenocrysts’ of Pirsson).
But, where locally and accidentally there was sudden relief of pressure
and shattering of the magma, accompanied by rapid chilling, as
near the small xenoliths of sandstone and marl, the characteristic
basic glass of the limburgites, full of minute vesicles, resulted
instead of analcite.

1 The possibility of the local absorption by the magma of silica, etc., from
the xenoliths must be taken into account; but it seems more probable that the
Operative cause in the formation of the glass was the one stated.

2 The finely powdered rock, when digested with very dilute (5 per cent.)
hydrochloric acid, yields gelatinous silica,

470 PROF, W. 8. BOULTON ON A MONCHIQUITE INTRUSION [Nov. rortt,

LV. CuemicaL Composition.

An analysis of the rock? has been made by Mr. Sydney J. John-
stone, of the Imperial Institute. It is given below, with some
others for comparison :—

ue | iE TEE f: EVE We
Per cent. | Per cent. | Per cent. | Per cent.} Per cent.
SOR eee sehen 40:26 39°54 42°22 44-01 42°46
UPUO) sere de eee oc dates 2:26 || 22 2°49 2°03 2°47
PAU RO sete rcierces schiciwe as LO 225 Ao Sa 10°62 12:32 12°04
COW ee canes 7:14 y itets) 6:18 8:75 5:34
les Ope eacn see csstecene | 2°86 4:05 4-74 3°62 3:19
CG) Ss Same oe are er trace || das 0°10 trace Bh
ROME AM cee pene vas ae a 0:05 Pre ae
in Oink O09 ae eR eee 0:20 0-40 0°50 0-21 0-16
(COT Cee eee is 0:05 0°05 trace ay
SO) Mu et eo ae, me 0:19 0-04 ie undet.
CAOiE Cee ees 13°48 9-64 14:80 10°57 12°14
1 (2 0 ie ee Reo 8:75 8:66 8°68 12°86 12°40
EON oe dakst ate aor 32 3°70 1:41 0:49 2°68
WNECOS st.c cag hemecienats ik 2°24 2°46 1:68 1-21
AOR Tootlaoi dost st son 0°65 1:01 0°73 0-17 0-84
BOs reste sauna senses 0°62 ee ioe ap none
Seri es ar nce ard ICR ie ae O12 0-11 ix
1 Eels Nene cas eso meaty. “ie | O27 Sal eet ip
COR) ersmicataswenetes 5:80 2:48 Sit trace 0:55
(Bi aries. eae ata NE AE ae ai trace Aon see cae none
HZOrat LOD Cs ai: 1-24 0-61 0°50 0-89 || 4-03
H,O above 105° C.... 3°53 UG. eis Die \ e
Moballs eas 2shtraen 99:79 || 99-92 100°42 100°44 99°51

I = Monchiquite near ‘Great House,’ Golden Hill, Monmouthshire, (Anal.
S. J. Johnstone.)
II = Nepheline-ouachitite, Kilchattan, Colonsay. (Anal. E. G. Radley.)
‘The Geology of Colonsay & Oronsay, with part of the Ross of Mull’
Mem. Geol. Surv. Scot. 1911, p. 46.

III = Camptonite, Sailean Sligenach, Ardmucknish, Argyllshire. (Anal.
E. G. Radley.) See ‘The Geology of the Country near Oban &
Dalmally ’ Mem. Geol. Surv. Scot. 1908, p. 126.

IV = Olivine-dolerite, Ciche na Beinne Deirge, Skye. (Anal. W. Pollard.)
See ‘The Tertiary Igneous Rocks of Skye’ Mem. Geol. Surv. 1904,
p. 825; also ‘Geol. of Colonsay, Ke.’ op. supra cit. p. 46.

V = Monchiquite, Willow Creek, Castle Mountain district, Montana (Weed
& Pirsson, Bull. U.S. Geol. Surv. No. 1389, 1896, p. 115). (Anal.
L. VY. Pirsson.)

The specific gravity of the Monmouthshire rock is 2°85. It has

* Tn selecting material for the analysis, care was taken to exclude, as far as
possible, xenoliths of Old Red Sandstone and picrite. As shown on p. 473,
fragments of the latter would not appreciably affect the result; while the
former, if present, would have the effect of slightly raising the percentage of
silica and alumina.

Vol. 67.] IN THE OLD RED SANDSIONE OF MONMOUTHSHIRE. 471

a low percentage of silica ‘ and alumina, and a high percentage of
lime, magnesia, and iron, while the alkalies are only moderate in
amount. Thus the composition is that of a typical basic lam-
prophyre, which is fully borne out by the petrographical characters
already described.

The presence of phenocrysts of augite, biotite, and olivine, the
abundance of augite-prisms and biotite-flakes in the matrix, the
absence of felspars, and the presence of analcite as a colourless
isotropic base, mark it out as a monchiquite.?

That the gap between the monchiquite and the limburgite types
is not considerable would appear probable, seeing that both occur
in close juxtaposition as variations of the same rock ; not, however,
by a change of the basic glass into analcite, but by the practically
simultaneous formation of glass and analcite under somewhat
different conditions, apparently in the main a different rate of
cooling.

An unusual amount of carbon dioxide appears in the analysis,
and this was to be expected in view of the great development of
carbonate revealed by the microscope. Some of this carbonate may
possibly be in the form of dolomite, but most of it is calcite. The
finely-powdered rock, and the ocelli in hand-specimens, effervesce
vigorously with very dilute hydrochloric acid. Thus, in comparing
the composition of this rock with that of others showing less
carbon dioxide, it will be necessary to make some deduction from
the lime-content.* The soda is rather smaller in amount than
anticipated, and less than in most rocks that have been described
as monchiquites.* The alkalies of the monchiquite group vary
greatly in amount; in nearly all cases the soda is in excess of the
potash.

V. Tue Oxivine-Aveite-Rock Incivsions.

We will now consider the inclusions or ‘ nodules’ of somewhat
coarsely-crystalline rock, which contain the conspicuous, bronzy,
mica-like substance, and are obviously quite distinct from the pheno-
erysts of augite and biotite, as well as from the xenoliths of Old
Red Sandstone.

Seen under the microscope, the junction of one of these inclusions
and the containing rock shows clearly a corrosion-border of faintly-
polarizing granular material with much iron-oxide; and the

1 Three additional determinations of silica were made of three different
specimens of the rock in the laboratory of University College, Cardiff. The
results were 40°75, 41:04, and 42°53 per cent. respectively.

* The term monchiquite as here used is in the sense advocated by
L. V. Pirsson, who showed that the ‘ pitchstone-glass’ of the original mon-
chiquite of Hunter & Rosenbusch is really analcite (see Journ. Geol. Chicago,
vol. iv, 1896, p. 679).

3 Tf all the carbon dioxide is combined with lime, and all the calcium
‘carbonate is of extraneous origin, the percentage of lime in the analysis would
be reduced to the extent of about 7°4.

4 The monchiquite from the Castle- Mountain district, Montana (see
Analysis V, p. 470), contains only 1:21 per cent. of soda.

472 PROF, W.S, BOULTON ON A MONCHIQUITE INTRUSION [Nov. 1911,

monchiquite near the contact usually shows the dark-brown, glassy
matrix already described as characteristic of the vicinity of
xenoliths.

Allotriomorphic crystals of olivine make up perhaps the bulk
of the rock, showing the characteristic cracks, but with none of the
original mineral left. In its place is a colourless or grey substance |
(carbonate)* with fibres and scales of serpentine and iron-oxide,
Beautiful examples of stellate and dendritic growths of magnetite

~ occur.’

Associated with the olivine is the mica-like mineral, which
is so conspicuous in hand-specimens of the nodules. Macro-
scopically, it is dark green or brown, often with a pronounced
schiller or bronzy lustre, and a strong cleavage, so that it can
be peeled off by a knife into flakes which are very soft and brittle,
and easily crush into a greenish-yellow powder.

Thin sections are yellow and green or pale reddish-brown by
transmitted light, in nearly ail cases distinctly pleochroic, the
colour being green or bluish-green for vibrations parallel to the
short axis of the polarizer, and yellowish for vibrations at right-
angles. The cleavage is very marked, and extinction invariably
takes place parallel to it. Cleavage-flakes, examined separately,
show a variety of colour by transmitted lght, from bright yellow
to green and brownish-red. A yellowish-green flake, with fine
striations and faint granular patches and slight dichroism, gave in
convergent polarized light the acute bisectrix of an interference-
figure, with a small optic axial angle, and with the optic axial —
plane disposed parallel to the length of the flake. Another flake,
with clusters of very minute yellow-brown granules, showed fine
striations along the plane of main cleavage, and between crossed
nicols a marked fibrous or rod-like structure, with the fibres
polarizing brilliantly, and in separate bundles.

The double refraction is strong, the interference-colours belonging
to the second order. In one or two places, the habit and optical
properties generally show a striking resemblance to biotite.

The rods, fibres, and lamelle appear to start from one transverse
crack, and extend perpendicularly to the next transverse crack.

There seems to be no douot that this substance is an alteration-
product of the olivine, and it closely resembles the mineral
iddingsite, regarded by some mineralogists as a definite variety
of serpentine.

It is just possible that bastite- pseudomorphs after a rhombic
pyroxene occur in these nodules, for a few patches of the paler
variety of the green substance suggest it; but, so far, no ee
determination has been made.

Allotriomorphic plates of pale-green augite, often partly or

1 The finely-powdered rock, when treated with very dilute hydrochloric acid,
shows, under the microscope, a vigorous reaction in the fragments of this
altered olivine.

2 See J. W. Judd, ‘On the Tertiary & Older Peridotites of Scotland’
Q. J. G.S. vol. xli (1885) p. 382.

Vol. 67.] IN THE OLD RED SANDSTONE OF MONMOUTHSHIRE. 473

entirely surrounding the olivine, bear an unmistakable resem-
blance, both in colour and association, to the chrome-diopside
of some of the picrites and lherzolites. In places, an approach to
the diallagic structure was observed.
_ Irregular grains and patches of translucent chromite or pico-
tite * are plentiful, up to 6 mm. across, usually of a deep yellowish
colour, but sometimes yellow-brown, and in one or two small
. patches they have a deep green colour, possibly indicating pleonaste.
: A bright yellow-green substance often extends for some distance
from the margin of the chromite-grains, and is found also in the
racks of adjacent minerals ; it is, presumably, chrome-oxide.

The rock is unquestionably a peridotite, and approaches to a
coarsely-crystalline picrite (Pl. XXXVII, fig. 6). The question
arises as to how far these corroded xenoliths of picrite are related
to the monchiquite. The diopside, olivine, and chromite of the
picrite are minerals which occur as phenocrysts in the monchiquite,
except that the augite of the picrite has the additional diallagic
structure slightly developed, while the olivine tends to pass into the
iddingsite product, rather than into the usual serpentine. More-
over, the chemical composition of the picrites agrees very closely
with that of our monchiquite. For purposes of comparison, the
analysis of a picrite is placed alongside that of the Monmouth-
shire monchiquite, and the close similarity is at once detected :—

i, di
Per cent. Per cent.
SIO wots dave ates ooo 40°26 42°85
iO). Seria sea Neco 2 2°26 a
W720 Manele ie Ae ee (A: 6°86
OO eee yen tesiar 2°86 6:27
Al OF cep anime pee cee ide; 10:22 10°42
EO tet eee eee ey sl trace ee
Mn) ope oe eee ee 0-20
CONS shane as a ee 15°43 11-84
MgO eerie ee ancnee thie 875 9-01
KO coed ate oes eer erica 1°32 161
Na; O! cs Scoot ace 151 1-65
POs axneebae mete eee 0°65 si
SO) tiene sapeeoee ee 0:62 -
CO... paieeeaer ere seeds 5°80 5°88
HO ap l0n? Ge ee 1:24 \ 2-70
HO above 105°C. ...... 3:53 teat
Motealery ss rsts 125k 99°79 99°09

I = Monchiquite near ‘ Great House,’ Golden Hill, Monmouthshire, (Anal.
S. J. Johnstone.)

II = Altered picrite from Sohle (see J. J. H. Teall, ‘ British Petrography
1888, p. 180). This has suffered a change whereby magnesia has been
removed and lime introduced. A similar change in composition has
been effected in the Monmouthshire monchiquite and its picritic
inclusions.

1 The heavy particles were separated from the powdered rock, and gave the
chromium-green colour with the borax bead,

474 PROF. W. 8. BOULT)N ON A MONCHIQUITH INTRUSION [ Nov. 1911,

The conclusion would appear reasonable, therefore, that the two
rocks—the included picrite and the enclosing monchiquite—are
nearly related. Unlike the xenoliths of Old Red Sandstone, which
are ‘accidental,’ these picritic nodules must be regarded as ‘cognate,’'
and they probably represent portions of the already consolidated,
deep-seated magma from which the monchiquite had its source,
portions which were carried upwards by the latter in its violent
intrusion into its present position.?

VI. AFFINITIES WITH OTHER Rocks.

When a hand-specimen of the rock, with conspicuous crystals of
augite and biotite, was shown to Dr. Flett and Mr. H. H. Thomas,
they at once recognized its striking resemblance to some of the
basic lamprophyres of Colonsay, recently described by the Officers
of the Geological Survey in a memoir now passing through the
press. ‘Through the courtesy of the Director and Dr. Flett, I have
been able to look over some of the proofs of this memoir, and I have
also examined some of the typical rock-specimens and microscope-
slides described therein.® .

Among the minor intrusions of Colonsay, one in particular
closely resembles the Monmouthshire rock in many respects. It
has the same black, glassy look, with small pink and white ocelli
and with large corroded phenocrysts of augite and biotite. There
are minor differences: thus the Colonsay rock contains hornblende-
phenocrysts and no olivine, and the biotite is more abundant in
the ground-mass, while the rock on the whole is somewhat fresher
than the Monmouthshire rock. Dr. Flett classes it with the
* ouachitites ’ of J. F. Williams.*

Except for the higher alkalies, it will be seen (p. 470) that this
Colonsay rock is very closely allied chemically to the Monmouth-
shire rock. The associated analcite-bearing dolerites (crinanites)
of Colonsay and the camptonites of Argyllshire, especially the
Ardmucknish rock, the analysis of which is quoted on p. 470, are
also very similar in composition. So, too, are the monchiquites of
America, described by Pirsson, Weed, and others: an analysis of
one of these American rocks appears in the last column on p, 470.

It becomes important to enquire whether the basic intrusion
into the Old Red Sandstone at Bartestree, near Hereford,’ some
30 miles north-north-east of the Monmouthshire monchiquite, and
the only other igneous intrusion in the Old Red Sandstone cf the
South Wales area, is in any way related to the rock which we are
now considering. Unfortunately, no analysis of the Bartestree rock

1 See A. Harker, ‘The Tertiary Igneous Rocks of Skye’ Mem. Geol. Surv.
1904, p. 351, and Journ. Geol. Chicago, vol. viii (1900) p. 394.

2 <The Tertiary Igneous Rocks of Skye’ op. ct. p. 362.

3 The memoir has been published since the above was written.

4 «The Igneous Rocks of Arkansas’ Ann. Rep. Geol. Surv. Arkansas for
1890, vol. ii (1891) p. 393.

> §. H. Reynolds, ‘ The Basic Intrusion of Bartestree’ Q. J. G.S. vol. lxiy
(1908) p. 591.

Quart. Journ. Geo. Soc. Vou. LXVII, PL. XXXVII.

x 20

W. S. Boulton, Microp’ Bemrose Ltd., Collo., Derby.

ROCKS FROM THE MONMOUTHSHIRE MONCHIQUITE-DYKE. i

Vol. 67.] IN THE OLD RED SANDSTONE OF MONMOUTHSHIRE. 475

has been published, but it is significant that one of the variants of
that composite dyke is a dark, heavy, and very basic analcite-
dolerite or teschenite, with a silica-percentage of 43°03 and
specific gravity = 2°88 (op. ct. p. 509),

With regard tothe age of the Monmouthshire intrusion,
the only certain fact is that it is later than the Upper Old Red
Sandstone. In the memoir referred to above, Dr. Flett discusses the
age of the monchiquite and olivine-dolerite dykes of Colonsay that
have a north-westerly trend, and says that
‘they belong to a series which has a wide distribution in Argyllshire and the
adjacent part of the West Highlands.’ !

That they are post-Carboniferous seems certain, but whether they
are of the same age as the Tertiary dolerite-dykes of Skye and other
parts of Western Scotland is still an open question, and need not
be discussed here.

The Beinn Dearg dykes of the Red Hills of Skye, which are low
in silica, comparatively poor in alumina, and rich in magnesia, are
regarded by Mr. Harker as a
‘highly specialized derivative from the hypothetical common stock.’ ?

It may be that the monchiquites of Colonsay are a still more pro-
nounced yariant in this same basic series of Western Scotland.

In much the same way, the Monmouthshire monchiquite and the
dolerite of Bartestree may be related to each other, and derived
ultimately from a common magma; so that, whereas the teschenite
of the Bartestree dyke shows some considerable departure from
the normal stock, the monchiquite may be regarded as a more
extreme variant.

VII. Summary.

The rock here described is the only example of a monchiquite so
far recorded in England and Wales. It is intrusive in the Upper
Old Red Sandstone of Monmouthshire, either as a wide irregular
dyke or a plug.

It is remarkable for its large corroded phenocrysts of augite,
biotite, and olivine.

It has incorporated many lumps and chips of the country-rock,
with the usual metamorphic changes in the xenoliths; and in their
vicinity the rock becomes locally, but to a very subordinate extent,
a limburgite, with the more normal glassy base.

Cognate xenoliths of picrite are also included, which probably
represent the more abyssal equivalent of the monchiquite.

Petrographically and chemically it is very like the monchiquites
and camptonites of Scotland, especially of Colonsay; and it may be
regarded as a specialized and ultrabasic variety of the same magma
that yielded the analcite-dolerite of Bartestree, near Hereford.

* «The Geology of Colonsay & Oronsay, with part of the Ross of Mull’
Mem. Geol. Surv. 1911, p. 41.

* «The Tertiary Igneous Rocks of Skye’ Mem. Geol. Sury. 1904, p. 326 (see
analysis on p. 325).

Q.J.G.8. No. 268. 2

476 MONCHIQUILE INTRUSION IN OLD RED SANDSTONE. [ Noy. rg11,

I wish to express my indebtedness to Dr. Flett for very kindly
advice, for examining some of my rock-sections, and for the loan of
specimens from Colonsay; to Mr. Herbert H. Thomas for calling
my attention to the Colonsay rocks; and to Prof. Sollas for the use
of the apparatus in the University Geological Laboratory at Oxford
for photographing the rock-sections.

EXPLANATION OF PLATE XXXVII.

Fig. 1. Shde M 411. Showing a nearly colourless augite (chrome-diopside)-
phenocryst with corrosion-border and added zone of purple-brown
augite. The rest of the field is the dark-brown monchiquite matrix,
with small crystals of augite and olivine. X 20 diameters.

2. Slide M 404. Monchiquite with plates of biotite, the two near the top
of figure enclosing an olivine-crystal. In the left upper corner and
on the right are larger corroded and decomposed olivine-crystals.
The ground-mass is dark grey, with octahedra of iron-ore and small
olivine-crystals. > 20 diameters.

3. Slide M 403.. Monchiquite, showing in the lower part of the figure a
reddish-yellow biotite-crystal, and to the right of the centre a dark
reddish-brown chromite-granule. The dark-grey ground-mass encloses
small prisms of pale-brown augite, with a few small olivine-crystals
and granules of iron-ore. X 20 diameters.

4A, Slide M 401. In the lower right-hand corner is part of an Old-Red-
Sandstone xenolith (measuring half an inch across). Three lapilli of
dark-brown and reddish-brown palagonite, enclosing crystals of augite
and small round vesicles, make up half the field. They are embedded
in a colourless or light-grey matrix, consisting mainly of carbonate,
with small lapilli of glass and granules of quartz. x 20 diameters.

©. Slide M 420. Junction of the Old Red Sandstone xenolith, showing
the local development of basic glass. On the left is part of the
xenolith, with corroded border; in the centre is dark-brown glass
enclosing pale-brown augite-crystals and vesicles ; on the right is the
monchiquite with analcite ground-mass. Xx 20 diameters.

6. Slide M 415. Cognate xenolith of picrite. To the left and in the
centre is a large plate of very pale yellowish-green chrome-diopside,
enclosing serpentinized olivine. Near the top is another area of
decomposed olivine, partly surrounded by augite; while the dark
patch on the right is deep greenish-yellow translucent chromite.
x 20 diameters.

Discussion.

‘Dr. J. W. Evans remarked on the similarity of the large augite
‘mentioned in the paper with that described by Heddle from the
voleanic neck at John o’ Groats. He also referred to the fact
that the analcime ground-mass of monchiquites represented the
only case known in the consolidation of rock-magmas, in which a
eutectic residue was a definite chemical compound instead of a
mixture. The low melting-point of analcime, which was less than
that of any other original mineral constituent of igneous rocks, was
due to the fact that it contained water; and it was the presence
of water in the magma that determined the occurrence of
monchiquite, rather than that of a basic rock containing plagioclase

and nepheline.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. A477

17. The CarponireRous Succussion in GownR (GLAMORGANSHIRE),

with Nores on its Fauna and Convrrions of Dxposition. By
Ernest Epwarp Leste Dixon, B.Sc., A.R.C.Sc., F.G.S., and
ArtrHur VaueHan, M.A., D.Sc, F.G.8S. (Read March 9th,

1910.)
[Pirates XXXVIII-XLI.]
ConTENTS.
Page
I. Introduction (with Maps on pp. 478-79) .......:..0..c.ceesesccasecsceses 477
II. Lithological Characters of the Zones (HE. H. L. D.) ...............eeee 480
(1) Eastern District.
(2) North-Western District.
(3) South-Western District.
(4) Tabulated Synopses of the Sequence :—(i) in each District ;
(ii) generalized for the whole Area.
III. Note on the Pseudobreccias of the D-Zone (E. E. L. D.)............... 507
IV. Note on Lagoon-Phases and the Saian of Radiolarian Cherts
(KE. E. L. ‘D. eae oA oon eae mat: aka dencansudacrcascasesdunde dll

(1) Introduction and Definition.

(2) The Modiola Phases—Calcareous Lagoon-Phases—of Gower.

(3) The Radiolarian Phase—Cherty Lagoon-Phase—of Gower.

(4) Meaning of the Difference between the Modiola Phases and the
Radiolarian Phase of Gower.

(5) Topographical Position of Lagoon-Areas.

(6) Earth-Movements accompanying Lagoon-Conditions.

(7) Lagoon-Phases outside the South-Western Province.

Y. Interpretation of the Lithological Sequence (E. E. L. D.) ............ 532

(1) Preliminary Remarks.

(2) Variations in Depth and other Conditions of Deposition over
Gower as a whole at Successive Times; Conclusions; Earth-
Movements.

(3) Relations between the Different Districts of Gower at Suc-
cessive Times; Conclusions; Earth-Movements.

Summary of §§ IIT, 1V, & V; Acknowledgments.
VI. Notes on the Delimitation of the Upper from the Lower Avonian
in, the Sopll-Wewerm (Prowinee: 6.) 027.512. 2-ieasedo<n sce denessaccsoeces 542
(1) From the Stratigraphical Standpoint (H. E. L. D.).
(2) From the Faunal Standpoint (A. V.).

ube. Wasnt Pitas Cae eset ee eee cee ee ek ek 8 0 oe, so akaons Hicceadeoas 543

WEt: Palsomtolapieal gma regeees Vi seen ire atopic ni. canes coksaeesdaudceseee 553
(A) Corals.
(B) Brachiopods.

IX. Summary of Paleontological Sections ...............s.sceesessecencseeees 565

I. Iyrropucrion [E. E. L. D. & A. V.].

Tue object with which the Avonian rocks of Gower (figs. 1 & 2)

described in the present paper were examined was primarily the

comparison of their faunal sequence with that of Bristol and other

parts of the South-Western Province. In this connexion valuable

pioneer work on parts of the sequence had already been done by
2u2

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480 MR. E, E. L. DIXON AND DR. A. VAUGHAN ON’ _[ Nov. 1911,

Dr. W. B. Gubbin’*; and it was desired that our knowledge
should be extended to the whole development, as also to the
relationship of the zones that are based on brachiopods and corals ”
with the representative of the Pendleside Series which had been
recognized in Gower by Dr. Wheelton Hind.’ For in Gower
alone of the whole province was such a representative known.*
Between 1899 and 1902 the area had heen mapped by the officers
of H.M. Geological Survey, Dr. A. Strahan, Mr. R. H. Tiddeman,
and Mr. B. S. N. Wilkinson, and our work was greatly facilitated
by the knowledge then obtained, which was generously placed at
our disposal and has since (in 1907) been published in the official
maps and memoirs.’

Our joint field-work, the examination of the Mumbles-Bishopston
eround and the southern coast, was carried out in 1905, and in the
following year one of us (EH. E. L. D.) extended the work into the
north-western part of the area in connexion with the Geological
Survey; a summary of the information then obtained has since

been published.°

II. Lirmoroeicat Cuaracrers or THE Zonss [E. E. L. D.].

The Avonian rocks of Gower (see map, fig. 2, p. 479, based on the
Geological Survey maps previously mentioned) form part of the
southern margin, the ‘South Crop,’ of the South Wales coal-basin.
They present several outcrops, ranging west-north-west on the
whole, as they have shared in the powerful Armorican folding
about axes having that direction, which is the dominant structural
feature of the whole area. The folds are chiefly elongated
periclines, and the several Avonian outcrops along the limbs are
continuous one with the other.

These outcrops represent the deposits of an area of the Avonian
sea which extended for some distance both eastwards and west-
wards (that is, parallel to the coast-line lying at no great distance to
the north), and northwards and southwards ; and the bearing of this
fact on the development in different districts will be pointed out.

In the east, between Mumbles and Cefn-y-Bryn, only one major
fold—the Cefn-y-Bryn pericline—appears above the sea, and the
Lower Carboniferous rocks which form its eastward-pitching ‘ nose,’
though presenting several outcrops on account of minor folding,
may be grouped together as the Eastern District. But in the west,
rocks of the same age occur over a wider extent of country. At

i Proc. Bristol Nat. Soc. ser. 4, vol. i (1905) p. 42.

2 A. Vaughan, Q. J. G.S. vol. xi (1905) p. 181.

3 Geol. Mag. 1902, p. 485; zd. 1904, pp. 402, 585-87.

4 Recently, Dr. Hind has correlated some beds at Tenby with the Pendleside
Series, Proc. Geol. Assoc. vol. xxi (1909) p. 179.

5 The Swansea sheet (N. S. l-inch map 247) and ‘The Country around
Swansea’ 1907; the Worms-Head sheet (N. 8. l-inch map 246) and ‘ West
Gower & the Country around Pembrey’ 1907. These memoirs will be referred
to as the ‘Swansea Memoir’ and the ‘ West Gower Memoir’ respectively.

5 West Gower Memoir, pp. 14-17.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 481

present, those in the most widely separated outcrops are 4 or
5 miles apart across the strike, but they must have been
deposited at a much greater distance from one another, seeing
that the intervening ground is traversed by several deep folds.
The northernmost outcrop, west of Llanrhidian, which is continuous
along the strike with that at Mumbles, will therefore be dis-
tinguished, under the name of the North-Western District, from the
southernmost, which lies between Port-Eynon Bay and Worms
Head, and constitutes the South-Western District. No attempt,
however, will be made to describe the whole outcrop of any part
of the series.

Note.—(i) In the: following descriptions the dolomites, unless
otherwise described, are ‘ contemporaneous,’ that is, they have been
deposited as calcite or aragonite, but altered to dolomite by the
waters of the Carboniferous sea,—shortly, therefore, after deposition.
They are concluded to have had this origin on account of a variety
of evidence, part of which has been published in the Swansea
Memoir, pp. 13-20, pls.i & 11. ‘ Vein-dolomites,’ due to a later
mineralization, and described in the same memoir, are frequent,
but have in some cases no obvious relationship with any visible
vein, appearing, then, to have resulted from diffuse percolation.
Such cases may occur in rocks which have been partly altered
‘contemporaneously.’ (ii) Thicknesses, unless stated to have been
measured directly, have been estimated from outcrop, dip, and
height ; the locality is added in each case.

(1) Eastern District.
Lower Avonian.
K=Czrerstorora Zone.

Lithological characters.—So far as known, Lower Limestone
Shales, that is, grey shales with subordinate fossiliferous lime-
stones,’ the latter weathering soft and ochreous. For Lower
Limestone Shales underlie, probably at no great distance, the
beds in Threecliff Bay referred to horizon (3, and the position of
horizon 6 is immediately above the Cleistopora Zone.

Limits.—Relations to beds above and below not seen.

Exposures.—Poor; near Penard Castle, and at Southgate.

1 The ‘limestone flags,’ 200 feet thick, exposed along Penard Pill below
Parkmill, and referred to this zone by Dr. Gubbin, Proc. Bristol Nat. Soc.
ser. 4, vol. i (1905) pp. 52-53, belong (on the evidence of the fauna which we
have obtained from them) to Z,, together, probably, with horizon 8. Their
proximity to the Old Red Sandstone, mentioned by Dr. Gubbin, is due toa
fault.

482 MR. E, E. L. DIXON AND DR. A. VAUGHAN oN’ [Noy. 1911,

ZA= ZAPHRENTIS Zone.

Z,=subzone of Zaphrentis konincki Edw. & H., Carr.
Z,=subzone of Spirifer clathratus M‘Coy.
Horizon £.

Lithological characters.—the lowest part of the Main Lime-
stone’; in descending order :—

Z.—Dolomites similar to the Laminosa Dolomites, that is, dark
grey, finely crystalline, with small scattered nests of calcite and
dolomite ; interbedded with unaltered, thinly-bedded, crinoidal
limestones, which are abundant in the lower part but die
away to a great extent, upwards, at about 100 feet above the
base of the Zone. Through the lowest 50 feet or so occur
impersistently-tabular cherts and beekitized fossils.

Horizon 8.—More thickly-bedded, crinoidal limestones ; several
yards exposed, but base not seen.

Fauna.—See pp. 544-45.

Thickness.— Of horizon 8+2Z, :—about 150 feet (Threecliff Bay),
on the assumption that the unexposed basal part of horizon / is
not much more than 10 feet thick. Of Z, alone not determinable
without difficulty ; of the dolomite-group, Z,+Zaminosa Dolo-
mites, 320 feet (Threecliff Bay).

Limits.—Horizon 6, atthe junction of the Cleistopora and
Zaphrentis Zones, is probably also the junction of the Lower
Limestone Shales and the Main Limestone. The junction of
Z, and Z, is not marked by any appreciable lithological change ;
the top of Z, could not be localized, owing to the prevalent
dolomitization, but evidently is also not defined lithologically.

Typical exposure,—Threecliff Bay, east side :—horizon 6 and
the rest of the zone in sequence.

C,= Lower Subzone of the Syrrvgoruyreris Zone.

2. Caninia Oolite.
1. Laminosa Dolomites.

The presence or absence of horizon y in Eastern Gower could
not be determined, owing to the dolomitization prevalent through
Upper Z and Lower C..

Lithological characters and thickness.—In descending
order :—

2. Caninia Oolite. As a rule a remarkably pure limestone,
distinguished from neighbouring horizons by its light-grey, often
white colour and thick bedding, but especially by the purity

1 This is merely a convenient name for the main limestone-mass of the
Lower Carboniferous ; no relationship to the Main Limestone of the North of
England is implied.

iz

iT

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 483

of its oolitic structure '—other material, such as crinoid-ossicles
and smaller organisms, being largely confined to subordinate
bands, while larger fossils amount to little more than a few
beds of brachiopods or Bellerophon and an occasional Syringo-
pora. Some bands, generally current-bedded, show evidence
of contemporaneous erosion in included, sometimes rounded,
fragments of oolite. Minute to microscopic ooliths are fre-
quent, in places to the exclusion of others, especially towards
the top. There, also, more often than elsewhere, the rock
is dark in colour. Chert is unknown, unless represented by
big, light-grey, concentrically-zoned siliceous nodules (Three-
cliff Bay); these, however, have not been critically compared
with the siliceous aggregates found later in North-Western
Gower. ‘The rock passes up from the dolomite below, through
intermediate phases in which the ooliths are less dolomitized
than the matrix ; and in places dolomite recurs in bands in the
lower part.

Thickness.—160 feet (Threecliff Bay); 125 and 70 feet
(Caswell Bay anticline); 150 feet (Longland Bay).

1. Laminosa Dolomites. Dark-grey or black, finely-crys-
talline dolomites,? chiefly representing fairly thin-bedded,
crinoidal limestones, with here and there a few such beds
still unaltered ; towards the top, where the dolomite is rather
paler and more thickly-bedded than below, it may be seen in
places that it represents oolite. As a rule, dolomitization has
obscured or obliterated most of the original constituents,
including, among the fossils, some of the crinoid-ossicles,
highly-resistant though they be. A feature of the crinoidal
dolomites and others of the same type (as, for instance, those
in Z) is the sporadic occurrence, throughout their mass, of
small nests, up to several inches in diameter, of a coarsely-
crystalline mosaic of glassy calcite and milky-white dolomite ;
on Wave-worn surfaces these nests contrast strongly with the
surrounding black rock. Many of them appear, from traces
of organic structure still preserved, to have originated, partly
through the alteration and recrystallization of calcareous mud,
inside fossils with internal cavities, such as gasteropods and
certain corals.

Thickness indeterminable (see Z,).

Fauna.—Little known (p. 546), the Zaminosa Dolomites having
lost most of their fossils, and the Caninia Oolite never having
had many,

* Under the microscope the grains, like those of most of the oolites of the
Gower Avonian, show a radial-fibrous as well as a concentric structure, and
differ thus from the S,-pisolites. They are approximately spherical, with a
diameter which in many is about 0-4 mm. and is seldom greater than 0°6 mm.,
but in the smallest measures 0°13 mm. or less.

2 The completeness of the dolomitization may be gauged from the fact that
an average sample, analysed for commercial purposes, was found to contain
20°35 per cent. MgO, the percentage in CaCO, . MgOO, being 21°9.

484 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON’ _[ Nov. 1911,

Limits.—The boundary between the two groups is merely the
somewhat uneven level at which the dolomitization characteristic
of the lower shows greatest diminution when followed upwards.
Unevenness of the level on a large scale would explain the
inconstancy in thickness of the Canznia Oolite, should it be
found that the total thickness of C, is fairly constant.

The top of the Caninia Oolite is sharply defined, and appears,
from the character of fragments in the overlying bed, to have
been slightly eroded, in places at least, prior to the deposition
of C,, though it is not channelled or corroded as at West
Williamston (Pembrokeshire).*

Typical exposures.—Threecliff Bay, east side. Caswell Bay,
east side :—several outcrops due to folding and faulting. This
disturbance, which amounts to an anticline the crest of which
has sagged down into a deep syncline with an overthrust from
the north for its northern limb, has been described and figured
by Dr. A. Strahan.? The ‘thick bed of light-coloured oolite ’
referred to by him is the Caninia Oolite, and the ‘dark and
thin-bedded limestones’ beneath are the Laminosa Dolomites
together, possibly, with the top of Z,. Thus the Caninia Oolite
has three complete outcrops and, in addition, a partial outcrop
due to a strike-fault' in the southern limb of the anticline.
Longland Bay, north side:—the Laminosa Dolomites with,
probably, the top of Z,; in and near Rothers Tor, the Caninia
Oolite.

Upper Avonian.

C,= Upper Subzone of the Srrzweorurnis Zone.’

2. Standard limestones.
1. Modiola phase.’

Lithological characters.—Of the beds in descending order :—

2. Standard limestones, that is, limestones with a standard
marine fauna, largely crinoids, corals, and brachiopods. The
limestones are chiefly lght-grey, rather thickly-bedded, and
highly fossiliferous, but are in some cases dark and more thinly-
bedded, especially those containing many gasteropods. Beds
of dark, finely-crystalline dolomite and partings of shaly
limestone occur, but are quite subordinate. In the gasteropod-
beds the gasteropods are replaced in many cases by dolomite,
even where the surrounding matrix has remained quite un-
altered. Selective dolomitization of this kind is found only
in organisms which have been originally aragonitic, such

1 «The Country around Haverfordwest,’ Mem. Geol. Surv. (in the press).

2 Swansea Memoir, p. 8, fig. 1.

3 As explained in § VI, the dividing-line between Lower and Upper Avonian
is now taken at the base of C,.

* The meaning of this term is explained on pp. 512 ez seggq.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 485

as gasteropods and orthocerates, but occurs at many Avonian
horizons throughout the South-Western Province. In view of
the instability of aragonite, this phenomenon is readily explic-
able, but implies that the organisms were still aragonitic when
dolomitized. Further, the wide occurrence of the phenomenon,
taken in conjunction with the short life of organic aragonite
under the conditions accompanying vein-dolomitization, sup-
ports the conclusion, based on other considerations, that the
dolomitization was ‘contemporaneous.’ Where there is no
independent evidence of ‘contemporaneous’ dolomitization, it
is found that organic aragonite has been replaced by coarse
calcite-mosaiec.

In places, the lowest bed contains fragments of the highest
of the deposits of the underlying Mocdiola phase.

1. Modiola phase. A variable group of limestones, dolomites,
breccias, and more or less calcareous shales or clay-mudstones,
thinly bedded to finely laminated or papery; grey, dull buff,

or greenish in colour (where free from Triassic reddening). .

The limestones, some of the argillaceous varieties of which |

are nodular and concretionary,’ are either fine-grained to |
compact, or very finely oolitic (these resembling parts of the

Caninia Oolite) or, occasionally, ‘ pisolitic.” Crinoidal lime-
stones are rare, and are merely thin lamine. Many of the
fine or compact limestones and dolomites fracture conchoidally,
and resemble ‘ chinastone-limestones’; but some are finely-
laminated : they are calcite- or dolomite-mudstones (see p. 516):

Either kind, but, it appears, more frequently the dolomitic,

has recrystallized in places to calcite- or dolomite-mosaic

of fine to coarse grain. Some finely-crystalline dolomites, .

however, may be ‘contemporaneons’ replacements of originally-

calcitic rocks. |
Ordinary detrital matter is frequent. The mudstones con-

tain fine clayey material, which may exceed the calcareous,

or, Im some cases, fine quartz-sand. Breccias, of limestone

and clay-mudstone fragments, measuring up to several inches :

in length, set in an argillaceous, calcareous, or fine-sandy |
matrix, may occur at any horizon. The fragments are similar

in structure and fossils, either to some of the intercalated beds, .

or, in the case of some in the basement-bed, to the Caninia i

Oolite below, and evidently have been derived from both :

sources by contemporaneous erosion. Undoubtedly far-
travelled material, other than clay and sand, appears to be .
absent, and the fragments show little, if any, rounding.

Some beds, however, have a brecciated structure, due in part ,
to the penetration of an alien matrix into calcite-mudstone, }

apparently along irregular cracks. The crigin of the structure

} The coneretionary structure here mentioned is the type usual in argilla-
ceous formations, not the peculiar structure of the ‘concretionary beds’ of the
Avon.

486

MR. E. E. L. DIXON AND DR. A. VAUGHAN ON’ _[ Nov. 1911,

is uncertain, but the mud appears to have been brecciated
am situ by desiccation and cracking, without complete separa-
tion into fragments (see p. 514, footnote 6).

It may be noted that where a calcite-mudstone has succeeded
a breccia with uneven upper surface, it has filled up the
inequalities and formed a level surface ; in the same way, but
on a larger scale, a compact limestone, the lowest bed of a
thin Modiola phase, fills up the inequalities in the upper surface
of the conglomerate at Pendine (Carmarthenshire), described
by Dr. Strahan.’

True chert is unknown, but quartz in the peculiar form of
minute, colourless and milky-white, zoned nodules of the size
of sand-grains, has been noticed in a microscope-slide of one
of the laminated limestones.

The following section illustrates the character of the phase
and its relations to the beds above and below :—

Junction of C, and C,.—Southern outcrop on the east
side of Caswell Bay.

Thickness in feet.
. Crinoidal limestones, resting sharply on
. Calcite-mudstone, white-skinned, filling inequalities in
. Breccia: consisting partly of black calcite-mudstone, some
of which is fragmentary, and some, though penetrated by
the matrix, apparently not completely broken up. The
matrix is mudstone and very fine sandstone. With Bed 8.
6. Thinly-bedded, fine-grained limestones, including oolites.
With ‘Beds 4& Ole ees, cues cides ees saan eee nee 11
5. ‘ Pisolite,’ consisting of black, flattened, concentrically-
laminated, calcitic ‘ pisoliths,’ up to 0°75 inch in diameter,
set in grey finely-crystalline dolomite; a few inches thick.
4. Thinly-bedded to laminated, compact, argillaceous lime-
stones.
3. Dark limestone and black shale, passing into ...............4.+ ji
2. Clay-mudstone, with angular or subangular fragments, up
to several inches in diameter, of fine-grained, dark oolite
such as is found at the top of the Caninia Oolite;
lenticular beds of black limestone in the upper part.
Restsysharpoliyzommen. .2:s2 os. eanclacnsehe sess ae sen eee eee 15
1, Fine-grained oolite, light or dark grey.

~10 65

Or

Total thickness of Modiola phase

Bed 1 is the top of the Caninia Oolite (C,); Beds 2-8 con-
stitute the C, Modiola phase; and Bed 9 is the base of the
standard limestones of C,,.

The base of C, presents the features described above, which,
in conjunction with the faunal peculiarities, show that it con-
stitutes a Modiola phase, wherever it has been examined in
the eastern district, except in Longland Bay. There it con-
sists of a group, a few yards thick, of dark, finely-crystalline
dolomites, similar to the Zaminosa Dolomites but containing

* «The Country around Carmarthen’ Mem. Geol. Surv. 1909, p. 81.

Vol. 67.1] THE CARBONIFEROUS SUCCESSION IN GOWER. 487

abundant specimens of Bellerophon; this, though sharply
separable, on account of its far more intense dolomitization,
from the immediately succeeding beds (limestones with dolomi-
tized Bellerophon), forms part of the standard limestones.

Fauna :—

2. Standard limestones.—Rich, especially in corals and
brachiopods; crinoid-remains ubiquitous. In their fossils the
lowest beds differ somewhat from the rest (pp.542—43, 546-47),

1. Modiola phase.—Poor, consisting in most beds merely of
fish-fragments, abundant ostracods, a Spzrorbis-like annelid,
or abundant Calcisphera(?).' The calcareous alga (Girvanella)
may be present, poorly preserved, in some coats of the ‘ piso-
liths.’ Standard forms—crinoid-ossicles and foraminifera—
are known only from rare laminz, in which, however, they
are abundant.

Thickness.—Total, between 200 and 250 feet (Threecliff Bay) ;
300 feet (Longiand Bay), The discrepancy does not appear to
be due to faulting. Of the Modzola phase alone, 16 to 20 feet
(direct measurement).

Limits.—The change at the top of the Modiola phase to standard
limestones is abrupt, and is accompanied in places by contem-
poraneous erosion, which has been sufficient locally, as may be
seen in Caswell Bay, to cut out some of the highest beds of
the phase. The top of the subzone, that is, C-S, the junction
of C, and §,, is not marked by any appreciable lithological
change. For this reason, it is frequently useful to
group the subzones C, and 8, as one division, C,+S..

Typical exposures :—

2. Standard limestones.—Threecliff Bay, east side. Caswell
Bay,—several exposures, the southernmost on the east side
being the best. Longland Bay, east side.

1. Modiola phase.—Threecliff Bay, east side, and Caswell Bay,
—seyeral complete exposures at each place, the display in
the syncline being particularly good. Note :—The outcrops of
the Modiola phase are easily found by reference to the under-
lying Caninia Oolite.

S=SeEuivuta Zone.

S,=subzone of Productus ‘ cora’ D’Orb., mut. §,.
S,=subzone of Canina bristolensis Vaughan.

The subzones were not delimited, nor examined so closely as
in the South-Western District; but the sequence was seen to be
much the same as in that district.

1 The organisms provisionally referred, here and on subsequent pages, to
Calcisphera are isolated spheres of calcite, with an average diameter of 0°05
to 0'l mm.,, the walls of which are thin and have a radial-fibrous structure,

488 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON’ [ Nov. rg11,

Lithological characters.—In descending order :—

S,:—2. Modiola phase. Chiefly ‘pisolites,’* oolites, forami-
niferal limestones, and calcite-mudstones, the latter in-
cluding the unfossiliferous white-weathering variety called,
from their porcellanous appearance, ‘ chinastone-limestones’ ;
fossils abundant (individuals, not species), notably Seminula
in beds with a dark, fine-grained matrix ; some beds dolo-
mitized. Contemporaneous erosion is evidenced in some of
the oolites by irregular fragments, also of oolite, measuring
up to 2 feet in length; in such beds dolomite, if present,
is more abundant in the matrix than in the fragments.

1. Standard limestones. Oolites, with some pisolites
and fine-grained hmestones; in many, few macroscopic
fossils, but others are coral-,* brachiopod-limestones, etc.
Contemporaneous erosion is evidenced in the same way as
in the overlying group. Dolomites recur at intervals.

S,:—Limestones, largely made up of crinoids, corals, brachiopods,
and, in some dark impure beds, gasteropods; dolomitic beds
at intervals ; chert-nodules and beekitized fossils, extending,
with the gasteropod-beds, possibly into the base of 8, as in
the South-Western District.

Fauna.—See pp. 547-48. The Modiola phase has not yielded
any of the peculiar forms generally present in such phases.

Thickness.—Of the whole zone, about 1250 feet (Longland Bay).
The subdivisions were not separately measured, but 8, was by
far thicker than §,.

Limits.-—The upper limit of 8, was not examined. The two
parts of S,, though separable in a broad way, pass insensibly
one into the other, the incoming of the pisolites abundant in the
upper part being quite gradual. The upper limit of S,is marked
by a rapid and considerable lithological and faunal change, thus:—

Junction of S, and D,.—Generalized from several exposures.

D,: Pseudobreccias of Tee ae or dolomite, with a typical D,-fauna from
the base upwards; in places a thin basal oolite.

Passage-beds: Current-bedded, fine-grained, and in part oolitic limestones
with Cyathophyllum; 15 to 20 feet.

S,: Modiola phase. Limestones of the types previously mentioned ;
Seminula ficoides in crowds, at intervals up to the top.

1 Much of the ‘ pisolite’ might more properly be termed ‘ contemporaneous
breccia,’ for it consists largely of more or less irregular masses, of various sizes,
of dense, amorphous-looking limestone, some only of which show a pisolitic
structure. ‘These latter consist of a layer of dense calcite, of fairly uniform
thickness, around an organic nucleus, generally a Semnula (double-valved) or a
coral-fragment, but they rarely, if ever, have a concentric structure of several
well-defined layers, though such a structure is frequent in the S,-pisolites of
the Avon. Under the microscope it is seen that the dense material may contain
Girvanella-like tubules, but also that much of it is structureless and of ex-
ceedingly fine grain, being devoid, apparently, of any necessary connexion with
these tubules.

2 None of the coral-limestones are unbedded through great thicknesses, and
thus differ from coral-reef limestones.

¥

_ ai

Wo). 67. | THE CARBONIFEROUS SUCCESSION IN GOWER. 489

Typical exposures.—Threecliff Bay, east side. Pwll-du Bay.
Whitesbell Point :—lower part of the zone. Longland Bay, east

side :—the whole zone, in sequence with those above and below.

Limeslade and Broadslade (Bracelet) Bays:—much of §8,, the ;

junction with D, at ‘Tutt and at Mumbles Head (in both the Middle

Head islet and the adjacent cliff). Bishopston Valley :—several |

exposures, including one of the same junction at the Sker. |

|

i

|

D= Drevwornrcitvmu Zone.

The development of the upper part of this zone in Gower differs
in important respects from that in the Bristol and Dublin districts, )
and kas therefore been subdivided on somewhat different lines. |
In Eastern Gower the following groups are present. Above the .
lower part of the zone, which is a normal development of D.,, .
comes a group of limestones, connected faunally with both D, and )
D,, and, therefore, referred to as D,,. This forms the top of the \
Main Limestone, and is followed by a calcareo-argillaceous group, !
the ‘ Upper Limestone Shales’ of the Geological Survey,’ which )
probably represents part of D,, but certainly extends to a higher
horizon and is therefore known as D, ,. A resemblance of some of .
its fossils to forms which are common in the Zaphrentis Zone led at |
one time, before the D,-fauna of County Dublin was known, to |
some controversy as to the systematic position of D,_,. It is now
clear, however, that, as Dr. Wheelton Hind maintained,” it occurs |
at the top of the Viséan. !

It is succeeded by an almost purely argillaceous group, which |
is included in the Millstone Grit by the Geological Survey and has }
been recognized by Dr. Hind as a representative of the Pendleside i
Series. And, though it is possible that the Pendleside Series is a }
phasal equivalent of part of the sequence of coral-and-brachiopod i
zones of some regions, the name Posidonomya Zone (P), already in |
use for it, will be retained. i

.
D,=0¢ Subzone. |

Lithological characters.—Chiefly light-grey, thickly-bedded |
limestones, many partly dolomitized. ‘The limestones are pre- |
dominantly of the type, peculiar in Gower to the D-zone, charac- i
terized by the remarkable ‘pseudobrecciated’ structure which |
has been described by Mr. Tiddeman’® and forms the subject
of a separate note (p. 507). Besides much obviously subsequent |

+ The disadvantages attaching to other names, such as ‘ Bishopston Beds,’ |
which have been applied to this group, have been stated by Dr. Strahan in ;
the Swansea Memoir, p. 21. It may be added that, as delimited by Mr. E. B.
Wethered & Prof. C. Lloyd-Morgan, the ‘Upper Limestone Shales’ of the
Avon,—for which Buckland & Conybeare originally proposed the name,—
include lower horizons than those of Gower. \

2 Geol. Mag. dec. 5, vol. i (1904) pp. 585-87. .

Swansea Memoir, p. 10. He observes the persistence and high horizon of |
these rocks, and groups them together as the ‘ Mumbles Head Beds,’

490 MR. E. BE. lL. DIXON AND DR. A. VAUGHAN ON [Noy. 1911,

dolomite, there are occasional large irregular bodies of dolomite,
similar in its coarse grain and its association with clay to the
dolomite characteristic of pseudobreccias, but evidently of some-
what different origin. Another peculiar feature of the pseudo-
breccias, noted by Mr. Tiddeman and difficult of explanation, is
the occurrence of numerous pits, as a rule circular, 18 to 30
inches in diameter and a foot deep, but also irregular and larger,
distributed evenly over the upper surface of some of the beds
(see Pl, XX XVIII, fig. 1, taken from an example in the North-
Western District) ; these pits are filled with grey, buff-weathering
clay or, less frequently, with coarse, light dolomite, and, at some
levels at least, underlie thin beds of clay continuous with their
infillings. A few cases have been observed of a pseudobreccia
passing laterally, in a short distance, into clay with limestone-
rubble.

Subordinate to the pseudobreccias are limestones of ordinary
types. In places a coarse-grained oolite marks the base of the
zone, and other limestones, dark or light, are intercalated at
higher horizons. The zone is, however, further distinguished by
the presence of thin coaly layers, also noticed in the first place
by Mr. Tiddeman (loc. cit.). Some, though thin and valueless like
the others, resemble many true coal-seams in their character
and association with underclay, and have probably originated in
the same way. Thus, an unusually good exposure at Colts Hill,
of one lying at a considerable distance from both the top and the
bottom of D,, showed in descending order :—

[Section near thin coal in D,.—Southern quarry at Colts Hill. ]

Thickness in feet.

4, Limestone pseudobreccia, with a standard marine fauna.
3. Coal-smut and finely laminated, carbonaceous shale; in all

AOU Be eRe Ne oe ee ates ges esis SE Cen: EEE eee 13
2. Underclay with frequent rootlets and much pyrite; passing
LEG sD NOLS) IHG) GINNING) eae ne bBesanasneccdodooecocecunceceonacccsuns noo: 35

1. Limestones, pseudobrecciated or ordinary. ‘The upper surface
of the highest is soft, but uneven (with projecting corals),
and it is uncertain whether it shows a passage or a non-
sequence into (2),

There is no need to postulate a different origin for the smut-
bed at Oxwich Point, though found by Mr. Tiddeman to contain
many small gasteropods.

Fauna.—see pp. 548-49.

Thickness.—Between 400 and 450 feet (Pwll- in Bay).

Limits.—The faunal change to D,, is not accompanied by
any noticeable lithological change.

Typical exposures.—Pwll-du Bay and Head. Mumbles Head
(including the Middle Head and the lighthouse islets) :—much of
the subzone, the dolomitic pseudobreccias conspicuous. North-
north-eastern face of Mumbles Hill :—dolomitic pseudobreccias, in
several cases ‘pitted.’ Oystermouth(Colts Hill southern quarry ):—

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 491

pseudobreccias, unweathered, contrasting strongly in appearance
with the weathered rocks on the coast. Bishopston Valley :—
the outcrops of the D Zone in the sides of the valley are too
narrow to accommodate its probable thickness, the cause of the
discrepancy being, doubtless, unexposed strike-faulting.

Di_>.-

Lithological characters.—Much as in D,, but the pseudo-
breccias disappear in the upper part. The following section
shows the sequence at Colts Hill, and also the relations to the
beds (D,_,) above :—

D_, and D,_,.— Colts Hill.

Thickness in feet.
T),-,:—‘ Black lias,—thinly-bedded, black, argillaceous lime-
stones and shales, one of the latter a foot thick;
cherts.
D,_,:--3. Thickly-bedded, fine-grained limestones including
oolite; the highest few feet dark, with black cherts,
the rest light grey and chertless : pure, except for
some dolomite and occasional shaly partings; about 50
. Dark, shaly nodular limestone, slightly dolomitized,
PHO MOM UIE ELON EACH 6.5 soc ctcnsheencsceeevsadeeceasdese nee 1-2
1. Thickly - bedded, light-grey limestones, including
pseudobreccias, continuous with those of D,; base
not determined owing to poorness of exposure, but
EHICRMEHS, BEBDADLY BOOM 51 5<- cece iuontndanoeveadvesenesaas 60

i)

Fauna.—See pp. 549 & 551. The Productus Band at Colts Hill
occurs at the top of Group1l. Caninia cornucopie, mut. D,_, was
observed in the dark limestone immediately below D,

Thickness.—Uncertain, but not more than 120 feet (Colts Hill).

Limit.— The change to D,_,, which is considerable as regards
both fauna and rock- types, is almost abrupt, and is emphasized
by weathering, as may be seen at Colts Hill: D_, remaining
hard limestone, but D,_, becoming soft, clayey ‘ rottenstones.’
The change is foreshadowed in the highest few feet only of D,, ;
there the fauna includes one of the corals abundant in D,_,,
while the rock is dark and contains dark cherts.

Exposures.—Pwll-du Head: top of cliff 300 to 400 yards
south of High Penard. Colts Hill northern quarry and an old
face between this and the southern quarry.

ad

ies |
[The ‘ Upper Limestone Shales’ of the Geological Survey. |

Lithological characters.—Limestones and shales with cherts,
the whole known locally as ‘black lias.” The limestones are
thin—generally less than 3 feet thick—and evenly bedded
(fig. 3, p. 492); almost invariably dark-grey or black, with a
white skin or crust of impurities where weathered ; crinoid-débris

Q. F. G8. Nov 268. 2M

‘CUTTOD *AIng Toe) -oj0gd TPH “OL

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‘ynouuashy yw hiusong ,svvy yoojig , 242 We Sayvys pun sauopsamy ““q—eE “sy

:

Pol, 67.) THE CARBONIFEROUS SUCCESSION IN GOWER. 493

and fine-grained matrix in varying proportions. They are argil-
laceous and some, at least, are dolomitized—the rhombohedra
being, as a rule, minute. The shale-bands and partings are
more or less calcareous and, though abundant, generally less
than 2 feet thick. The chert, largely made up of sponge-spicules,
is abundant in some beds, either as black flinty nodules, more
or less sharply defined from the matrix, or diffused and difficult
to detect except under the microscope; it also occurs as beekite,
replacing fossils, in some beds apparently in this form alone.
‘Rottenstones’: relations to the ‘Black Lias.’—The
‘black lias’ characters are retained only where the rocks are
unweathered. In places the beds, both limestones and shales,
have been completely altered by decalcification and oxidation to
light-grey or yellow-brown, so-called ‘ rottenstones** and clays.
The ‘ rottenstones’ are either friable and largely argillaceous, or
brittle, like porous earthenware, and partly siliceous—the latter
evidently representing diffusely-cherty limestones. Many are
cavernous with moulds of unsilicified fossils, and some display in
sharp relief many details, hidden in unweathered material, of the |
structure of silicified fossils. Wavellite* occurs in cavities and
joint-planes in the higher ‘ rottenstones,’ as in the overlying
radiolarian cherts.
The ‘ rottenstones’ and clays differ so materially at first sight
from ‘black lias,’ that their equivalence is masked; but the view
put forward by Mr. Tiddeman,’ that they have been derived by
process of ordinary weathering from such beds, is confirmed by
the relations of the two types exposed in the northern quarry
at Colts Hill. There, D,., which is carried by the dip from
top to bottom of the quarry, is followed by ‘rottenstones’ and
clays with cherts near the top, but by ‘black lias’ with the
same fauna at the bottom. Other paleontological evidence,
also, points to the equivalence of the two types: the fauna of the
Bishopston ‘ rottenstones’ being approximately the same as that
of the Oystermouth ‘black has’ (p. 551).
An explanation of the extensive character of the weathering
which the ‘rottenstones’ have undergone is probably to be
sought in the fact that the latter, so far as known, are situated
as at Bishopston, that is, at or near the top of the partly
dissected plateau which constitutes the whole of this part of
Gower; whereas ‘black lias’ is found at lower levels, as at
Oystermouth. It is believed that the conditions of minimal
run-off and denudation which characterize the top of the plateau
have lasted long enough to allow the rocks there to be completely
weathered to a considerable depth. In the valleys, where denu-
dation is rapid, the outcrops at lower levels are unweathered.

1 None of the beds have been worked for rottenstone ; they are not so fine-
grained as the material of that name dug for polishing-powder on the ‘North
Crop.’

2 First noticed by Logan: see Mem. Geol. Surv. vol. i (1846) p. 134.

3 Swansea Memoir, pp. 25-26.

2M 2

494 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON’ _[ Noy. 1911,

Fauna.—Abundant (p. 550).

Thickness.—At Oystermouth at least 175 feet, and possibly as
much as 350 feet, if, as is probable, the effects, in duplicating
outcrop, of the strike-fault shown on the Geological Survey map
between Oystermouth Castle and Colts Hill are negligible.

Limit.—The junction with the Pendleside Series, P, is nowhere
clearly exposed. D,_, and P are seen together in the Bishopston
road-cutting, but their relations cannot be determined with
certainty, as both are weathered and crumbling and their steeply-
dipping junction strikes along, and largely beneath, the road.
The section suffices to show, however, that D, , with its abundant
fauna is succeeded by a comparatively barren radiolarian-chert
group (the base of P), the change, which 1s great and far-reaching
both faunally and lithologically, being abrupt, if not marked by
an unconformity (see p. 529). Of unconformity, however, there
is no evidence, stratigraphical or paleontological, although the
junction contrasts strongly, in its abruptness, with the gradual
passage by alternation at Loughshinny.’

Typical exposures.—Oystermouth:—The Black Lias quarry
(fig. 3, p. 492) affords an excellent section of a thickness of 86
feet of beds in the condition of ‘black lias’ from near the top
of D,_, downwards; the sequence is without notable lithological
or faunal change, and only one limestone, the thickest (3 feet),
is sufficiently pure to make lime. In Colts Hill northern quarry
the lowest beds only are exposed. ‘ Black lias’ also forms the
intervening ridge on which Oystermouth Castle stands.

Bishopston :—In the cutting—chiefly along its south side—on
the Clyne Common-Bishopston Valley road, the top of D,_,, toa
thickness of at least 45 feet,> 1s exposed in the condition of
‘rottenstones. The sequence is obscured by weathering and
foundering, but has yielded a rich fauna, largely as moulds.

P= Posrponomya Zone.

This zone is represented by the Pendleside Series, first recognized
in Gower by Dr. Wheelton Hind.* He correlated, however, with
this series not only the beds now under discussion, but also the
D,_, ‘rottenstones.’ The composite group, thus constituted, had
previously been called ‘ Bishopston Beds’ by De la Beche* and
‘Gower Shales or Series’ by Phillips. As regards the beds above
D,_,, Dr. Hind’s correlation has been confirmed® by the subsequent

1 C. A. Matley & A, Vaughan, Q. J. G. S. vol. lxiv (1908) p. 418.

2 Details are recorded by Mr. Tiddeman, Swansea Memoir, pp. 22, 24.

3 Geol. Mag. 1902, p. 485; ibid. 1904, pp. 402, 585-87.

* Mem. Geol. Surv. vol. i (1846) pp. 183-34.

5 ‘Manual of Geology ’ 1855, pp. 169-70.

° Of the fauna quoted by him, Glyphioceras diadema (Beyrich) alone may be
regarded as of zonal value; and confirmation is, therefore, important.

Vol. 67.1] THE CARBONIFEROUS SUCCESSION IN GOWER. 495

discovery in them of Glyphioceras spirale (Phill.)+ and Posido-
nomya becheri Bronn (p. 552). The importance of distinguishing
between the ‘rottenstones’ and the overlying beds has been
recognized by the officers of the Geological Survey, who have

included the latter in the Millstone Grit, the ‘rottenstones’ (as

previously mentioned) being ‘ Upper Limestone Shales.’

Lithological sequence.—In descending order :—

2. Dark, well-laminated, non-calcareous shales, with some iron-
stone-nodules and thin sandstones; in the lower part with
black cherts?; according to De la Beche,® there is a thin
limestone (4 inches) in the middle. Very thick.

1. Radiolarian cherts* with interbedded shales, the cherts show-
ing the fine dark and light stripes, due to thin lamination,
frequent in radiolarian deposits, and the shales, also, well-
laminated and non-caleareous, but soft and in part weathering
to a chocolate colour. Under the microscope it is seen that
the cherts are exceedingly fine-grained, and that the dark and
light lamine differ one from the other in grain and in the
relative proportions of their organic and inorganic consti-
tuents, the latter chiefly the finest quartz-silt. Many of the
lamine are lenticular, some of them sharply so. Wavellite
occurs along joints. ‘The total thickness is slight, the group
forming, as it were, basal beds to the shales above.

Apparently, the series includes no recurrence of the fossili-
ferous limestones characteristic of the underlying Avonian.

Fauna.—2. Largely unfossiliferous, but some beds are crowded

with thin-shelled goniatites’ preserved as casts.

1. Of the abundant radiolaria and subordinate sponge-spicules
in the cherts, the former correspond closely with Culm forms.°
The shales are largely unfossiliferous, but some have yielded a
few lamellibranchs (p. 551) and indeterminate plant-remains.

Thickness.—Unknown, though probably at least 1500 feet, as
Glyphioceras spirale (Phill.) has been found in abundance at
apparently that distance above the base. Of this amount
probably much less than 50 feet belongs to the radiolarian-chert
group.

Limits.—The radiolarian cherts, doubtless, pass up into Group 2;

but the junction does not appear to be satisfactorily exposed,
and no repetition of similar cherts above is known. ‘The upper

1 By Mr. J. Pringle of the Geological Survey, Swansea Memoir, pp. 25 & 30;
the specimens, ‘J. P. 1260, 1265-1276’ in the Survey collection, were found
in a stream-bank on Barland Common, 150 yards west of Old Castle.

2 Swansea Memoir, p. 28.

3 Mem. Geol. Surv. vol. 1 (1846) p. 133.

+ Dr. Strahan has described in the Swansea Memoir, pp. 22-25, how the
discovery by Dr. G. J. Hinde of the radiolarian origin of these cherts resulted
from De la Beche’s comparison of the beds with the cherts of Codden Hill.
He appends Dr. Hinde’s description of the microscopic characters of the
rocks and their organisms.

5 Swansea Memoir, pp. 25 & 30.

6 Dr. G. J. Hinde in the Swansea Memoir, p. 28.

AG eee

—————O

496 MR. E. E.L. DIXON AND DR. A. VAUGHANON ([Nov. 1911,

limit of Group 2 has not been determined, but is not con-
spicuous lithologically, as the succeeding beds, up to the Coal-
Measures, are, also, largely shales.

Where examined.—Bishopston, north side of road-cutting :—
the radiolarian cherts. Barland Common:—the shales (Group 2);
the most complete section is now overgrown, but was described
by De la Beche! and has been discussed by Dr. Strahan.’

(2) North-Western District.

The sequence of the Avonian rocks in North-Western Gower is
similar on the whole to that in Eastern Gower, and attention
will, therefore, be directed chiefly to the differences between the
two districts. The Cleistopora Zone, however, is poorly exposed
in the Eastern district, and is described in some detail.

Most of the zones were examined along Burry Pill, the banks of
which, north and north-west of Cheriton, afford a fairly complete
sequence from a horizon low in the Zaphrentis Zone up to the
middle of D,, and much of D, was, also, found well displayed in
Tor-gro, a range of cliffs between Burry Pill and Landimore.
The thicknesses, estimated from outcrop and dip, in these localities
are stated in Table I (facing p. 505).

Cleistopora Zone,’? K.—This zone, although not completely
exposed, especially towards the top, probably corresponds exactly
with the Lower Limestone Shales, the resemblance to the develop-
ment in those parts of the South-Western Province where this
relationship holds good being close. It consists in descending order
of :—

Thickness in feet.
Probably K,. 4. Grey shales, with thin limestones containing
crinoids and brachiopods; upper part not seen;

total thickness probably between 250 feet and 300
K, or K,. 5. Limestones, including fine-grained dark oolite;

BLL CAIS bis titers crite wre flat soo netstat eid eee eee eae 30
(2. Like 4 on the whole; with Km ...................... 130
| 1. Modiola Phase, Km. Grey shales with ostracodal
Probably K,. { and oolitic limestones and a red hzmatitic
limestone of a-type; quartzitic sandstone with
U modioliform lamellibranchs near the base.
Motal ae between 400 & 500

The characters and thicknesses of Groups 1-3 and of 200 feet of
Group 4 were determined in the banks of a dingle, north-east
of Fairyhill House ; the total thickness of the zone was estimated
from its outcrop at Cheriton.

The base of the zone, as in most parts of the South-Western

1 Mem. Geol. Surv. vol. i (1846) pp. 133-34.

2 Swansea Memoir, pp. 22 & 30; also fig. 2 (p. 23).

3 The field-observations were made conjointly with my colleague, Mr. T. C.
Cantrill. I gladly take this opportunity of thanking him for encouragement
and advice at many stages throughout this work.

ol. 67. | THE CARBONIFEROUS SUCCESSION IN GOWER. 497

Province, is well-defined lithologically and, in a sense, paleonto-
logically also, the unfossiliferous, ‘ continental’ Upper Old Red
Sandstone giving place, rapidly but conformably, to the fossiliferous
marine Avonian. The junction, as exposed in the Fairyhill dingle

_ and recorded, with details of the adjacent beds, in the West Gower

Memoir (p. 8), is as follows. The top of the Upper Old Red
Sandstone is a barren, red marl with limestone-nodules (‘ race ’).’
The base of the Avonian is a grey, sandy limestone with limestone-
fragments, some ef which are red like the ‘race’ in the under-
lying marl, the rest being, doubtless, practically contemporaneous.
In the matrix between the fragments are a few ostracods and
ooliths, and the bed is followed immediately by the ‘sandstone with
modioliform lamellibranchs’ previously mentioned. The junction
of the Old Red with the Avonian is so sharp as to be clearly
traceable in a microscope-slide [E. 5288, Geol. Surv. Colln.]; and
though it partly owes its conspicuousness to the difference in
colour between the beds above and below, this difference is but
the outward sign of a fundamental change in the conditions of
deposition, marine organisms appearing in the rocks immediately
above. In Gower, it may be noted, the change (which is inferred
to be conformable from a merging of the top of the Old Red into
the Avonian) is almost abrupt, and has been accompanied by
current-action, as is evident from the fragments at the junction;
in some parts of the South-Western Province, on the contrary, as
for instance in Pembrokeshire,” marine and continental conditions
alternated for a space.

The junction of Km with Group 2 of K, and that of K, with Z
do not appear to be exposed. The limestone-group (3) probably
separates K, from K,, for it is exactly similar, lithologically, to the
limestone that affords the best boundary between these two sub-
zones in Pembrokeshire.

Zaphrentis Zone, Z.—Cherts are found, though only now and
then, above the group of limestones with cherts near the base of
the zone.

Syringothyris Zone, C.—The Caninia Oolite is_ partly
dolomitized at various horizons up to the top, the matrix between
the ooliths being the material chiefly affected. In places, the rock
has been partly silicified, the silica taking the form of numerous
aggregates of microscopic quartz-crystals; unlike the dolomite,
these replace ooliths and stop at the interstitial matrix.

The top of the Oolite is uneven, the irregularities reaching a
depth of a foot or more. But the hollows are not in all cases
simple depressions ; some extend into the Oolite laterally and are
overhung by roughly-horizontal tongues of it measuring up to a foot

1 The red marl, to a thickness of 4 feet, rests upon unfossiliferous, pebbly,

grey quartzite which is probably the top of the thick quartz-conglomerates
that form the upper part of the Upper Old Red of Gower (West Gower Memoir,

p- 9).
= ‘Summary of Progress for 1908’ Mem. Geol. Surv. 1909, pp. 35-36.

498 MR. E. E, L. DIXON AND DR. A. vaueHANON [Nov. 1911,

in length. Somewhat similar irregularities are known elsewhere
in shallow-water deposits, and have been caused by distortion of
originally evenly-bedded strata while still plastic, shortly after
deposition. It is possible, therefore, that the Caninia Oolite, also,
has been drawn out tangentially while in this condition, though
by what agency is not apparent ; in this case, however, it is equally
possible that the irregularities are due to some slight subaérial
corrosion prior to the deposition of C.,,.

The basal layers of the Modivla phase of C,, which follow the
Canima Oolite sharply and fill the hollows just described, are
puckered in a fashion suggestive of parts of landscape-marble.
At higher levels in the phase conglomeratic beds are rare in this
district ; and dolomite-mudstones appear to be restricted, as in
parts of Pembrokeshire, to a buff-weathering, argillaceous group at
the top. The fauna of the phase is devoid of standard forms,
and a Mtcheldeania-like alga’ (in minute fragments) is present;
otherwise the fossils are those found in the Eastern District.

The standard limestones of C, differ considerably in character,
though not in fauna—except in an absence or rarity of Caninia—
from the same subzone in the Eastern District. The chief differ-
ence lies in an absence of contemporaneous dolomite in North-
Western Gower, even the gasteropod-valves, which would be readily
affected by ‘ contemporaneous’ dolomitization, being wholly calcitic;
further, the beds are more uniform in character, rather darker
and less thickly-bedded than in the Kastern District. ‘They thus
approach the facies of the Seminula Zone of the outcrop north
of the coalfield.

Note.—Along the east side of Burry Pill the zone has been extensively
vein-dolomitized.

Seminula Lone, 8.—The lower subzone, S,, is similar on the
whole to the underlying standard limestones of C,, but includes,
though rarely, thin calcite- or dolomite-mudstones and, possibly,
a little dolomite that has ‘contemporaneously ’ replaced limestone ;
chert is absent. The top of the subzone was not seen.

In the §,-oolites, as in the Caninza Oolite, some ooliths have been
replaced by aggregates of microscopic quartz-crystals ; but dolomite
is wanting. In the Modiola phase which forms the upper part of
the subzone, mudstones, including ‘ chinastone-limestones’ and
nodular beds, appear to be better developed than in the Hastern
District, and dolomite is wanting. The change to the standard
conditions of Zone D at the close of the phase was rapid.

Dibunophyllum Zone, D.—The chief divergences in this part
of the sequence from the development in Eastern Gower are (1) an
absence of dolomite, as in C, and most of 8; (2) the presence of
a thick oolite at the base of D,; and (3) the presence of D..

(1) The absence of dolomite is most noticeable where the material
is known to be particularly susceptible to dolomitization; such

1 By this expression is meant a calcareous alga with a minute, radially-

columnar structure; such identification must suffice, until the revision of the
genera promised by Prof. E. J. Garwood is published.

Vol. 67. | THE CARBONIFEROUS SUCCESSION IN GOWER. 499

material is presented both by the valves of gasteropods and by the
unrecrystallized part of pseudobreccias. The latter, with typical
structure (see P]. XX XVIII, fig. 2) and abundant foraminifera, are
as widespread as in the Eastern District, but, like the gasteropod-
valves, are in all cases devoid of dolomite. In connexion with
pseudobreccias, it may be noted that one of the best exposures
of the ‘ pitted’ bedding-planes (p. 490) that characterize some
of them may be observed in Tor-gro, Landimore. One such
bedding-plune, dipping at a steep angle, which has been described
by Dr. Strahan in the West Gower memoir, p. 12,,is shown in
Pl. XXXVIII, fig. 1. The incoming of Cyrtina septosa (Phill.),
which varies in its horizontal distribution, is worth noting; in this
district it first becomes abundant near the base of the pseudo-
breccias.

(2) The D,-oolite, which is about 50 feet thick, is coarse-grained,
like the band in the same position in Pembrokeshire. The lowest
part is darker, more thinly-bedded and less oolitic than the rest;
otherwise the contrast with the Modiola phase at the top of S$,, im-
mediately below, is complete.

(3) D, has been recognized at Llanrhidian. In the top of the
Main Limestone the highest pee peer nared 3 in the neighbourhood has
yielded the following fauna!

Choneti-Productus. Martinia lineata (Mart.).
Papilionaceous Chonetes or Davie- Productus corrugatus M‘Coy.
siella. Productus edelburgensis-latissimus.

Martinia glabra (Mart.). Spirifer bisulcatus Sow.

The rock is a dark and bituminous, crinoidal limestone, rich in
brachiopods; unfortunately it is seen to a thickness of only a few
feet (in low crags 260 yards east of the church). It is underlain
by light-grey, nodular limestones, probably pseudobreccias, which
have yielded merely giganteid Productus and may belong either
to D, or to D,. Downwards in the sequence other beds are not
seen for some distance, and upwards nothing is known until the
radiolarian cherts* at the base of P are reached: it is uncertain,
therefore, whether D,_, is present in this district.

(3) South-Western District.

The structural features of this district, which lies between
Rhossili and Port-Eynon Bays, are shown and described in the
Geological Survey map and memoir.* Here we need only mention
that, owing to a syncline in the promontory south-west of Rhossili,
much of the sequence Z-C, is found along both the north-western
and the southern sides of the promontory, and that it is repeated
yet again near the Inner Head by an anticline ranging west-north-
west through the gut between the mainland and the Worms-Head
islets. The western extremity of the Worms-Head islets was not
examined.

1 Identified by Dr. Vaughan and preserved in the Geological Survey
Collection (E. D. 891-906).

* Poorly exposed in a lane a furlong east of the crags of D,-limestone.

° One-inch sheet 246 (Worms Head); West Gower Memoir, pp. 3, 12-16.

500 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON [ Nov. 1911,

As in the case of North-Western Gower, attention will be paid
chiefly to the differences between this district and those previously
described.

Cleistopora Zone, K.—Probably equivalent to the Lower
Limestone Shales. All the groups seen in North-Western Gower
appear to be present, and in the following account are referred to
under the same numbers as those on p. 496.

1. Modiola phase, Km. This group includes a 5-foot band of
conglomerate (exposed north-west of Rhossili rocket-house) of red-
brown quartz-pebbles, measuring up to half an inch in diameter,
with larger pebbles of fossiliferous mudstone or shale, the whole
in a matrix of calcareous sandstone which encloses, also, reddened
and rounded crinoid-ossicles like those in hmestones of a-type. The
conglomerate is both overlain and underlain by ostracod-shales with
limestones and sandstones, but probably lies near their base ;
the junction of those below with the underlying Upper Old Red
Sandstone is not exposed. The thin limestones interbedded with
the shales are chiefly of a type usual at this horizon, that is, most
of them contain a mixed fauna of crinoids, brachiopods, ostracods,
lamellibranchs, small Bellerophon-like gasteropods and Orthoceras,
besides fragments of contemporaneous sediments, including phos-
phates.

2. As in Pembrokeshire, the standard part of K, commences
with a group of quartzitic sandstones (Rhossili), and the parallelism
is maintained in the shales immediately below Group 3, which, as
exposed at the north-west foot of Hardings Down, are distinguished
by the markedly nodular character of their interbedded limestones.

3. As in North-Western Gower (and Pembrokeshire); exposed
at Hardings Down.

4, Not seen.

Zaphrentis Zoue,’ Z—In South-Western Gower, Z consists
largely of limestones, dolomites, though frequent, being subordinate.
Shaly bands are found, but at considerable intervals, through much
of the lower part of the zone: and cherts, with beekitized fossils,
have a considerable upward range (beekite being abundant in the
lowest beds—some part of Z.—exposed in the anticline at Worms
Head,* and cherts, with beekite, occurring for several hundred feet
above). :

As usual in this zone, the limestones are largely crinoidal and
rather thinly-bedded, and the dolomites dark grey and finely crys-
talline. The fauna is tabulated on pp. 544-45.

1 First recognized in this district by Dr. Gubbin & Dr. Vaughan, Proc.
Bristol Nat. Soc. ser. 4, vol. 1 (1905) pp. 50-52, 54.

2 The lowest beds in this anticline have been referred by Dr. Gubbin & Dr.
Vaughan (op. cit. pp. 50 & 54) to Z, on insufficient evidence. Their horizon
is probably lower than that of the lowest beds at Rhossili, rather than above
as stated by those authors, and it is agreed that the Rhossili beds (op. ct.
pp. 51 & 54) belong to Z;. The beds at both places were once considered by
myself to lie at the base of the zone (West Gower Memoir, p.15), but a
re-examination of the district, though leaving the age as Z, unquestioned, has
thrown doubt on their basal position, especially as regards the beds at Rhossili.

Ls
-

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 501

The boundary between Z, and Z, was not located, but is evidently
not marked by any striking lithological change ; the top of Z,, also,
is not conspicuous, as nodular and argillaceous beds, though most
characteristic of Horizon y above, commence in the highest part of Z,.

The most complete and accessible section lies between the core’ of
the Worms-Head anticline, at a level somewhere in Z, (see preceding
footnote), and the edge of the cliff at the Coastguard Station to
the north-east, which exposes the top of the zone and a few yards
of the overlying y beds. Here at least 530 feet (a figure obtained
largely by direct measurement) is exposed, but in this district the
full thickness of the zone cannot be determined.

Horizon y and Syringothyris Zone, C.—The chief points
to be noticed in this part of the sequence are :—

(1) Horizon y is well developed ;

(2) The Laminosa Dolomites are but partly dolomitized, and contain cherts
and beekitized fossils ;

(3) There is no Mediola phase at the base of C, ;

(4) The facies of C, resembles that of the standard C,-limestones of the
Eastern District, not that of the North-Western District.

(1) Horizon y consists of thinly bedded, nodular limestones with
soft argillaceous partings; this character is most marked in the upper
part. Fossils, especially corals, abound; they are magnificently dis-
played on extensive, weathered surfaces at Tears Point—the hest
Avonian collecting-ground in Gower, but unfortunately discovered
too late for its fauna to be recorded.

The base of Horizon y, defined as the level at which large
Caninids first become frequent, may be placed, to facilitate recog-
nition, at a rather marked argillaceous bed which reaches the sea
at Tears Point. The summit was placed, arbitrarily, but merely
for the purpose of measurement, at the lowest of the dolomites
which are the feature of the overlying Laminosa Dolomites, for
in the absence, so far as could be seen, of Chonetes cf. comoides
(Sow.) from the Laminosa Dolomites, there did not appear to be any
important faunal difference between this group and Horizon y.

(2) The lower part of the ZLaminosa Dolomites (for thickness,
see the table on p. 502) consists of about equal proportions of dolo-
mites of the usual character and of unaltered limestones ; the lime-
stones are rich in corals, and contain also some crinoid-cups. The
upper part is normal in its dolomitization, but includes occasional
chert-nodules and beekitized fossils. The change at the top to the
Caninia Oolite is rapid, that is, the thickness of dolomitized oolite at
the junction is small, and so too in North-Western Gower.

(3) Standard C, limestones follow the Caninia Oolite immediately.
Their basal bed is firmly welded to the somewhat uneven top of
the latter, and contains smal] masses of oolite (the outcome, doubt-
less, of a little contemporaneous erosion), which are mixed with
broken brachiopods, corals, ete., proper to C,,.

(4) The C, limestones are largely light- _grey and thickly-bedded,
and are less crinoidal than many parts of Z; probably fewer
dolomites and gasteropod-beds are intercalated than in Ceo

502 MR, E. B. L., DIXON AND DR. A. VAUGHAN ON [ Nov. 1911,

Eastern Gower. The subzone passes up insensibly into the similar
limestones which form the lower part of 8..

In the Caninia Oolite, it may be observed in passing, there are
thick bands of fine-grained, non-oolitic material, some of which
is foraminiferal, some comminuted-crinoidal; corals are more fre-
quent near the top of the Oolite than at lower levels, those noticed
being Michelinia, Syringopora, and a Clisiophyllid.

The thicknesses of the subdivisions of Horizon y and C, vary
somewhat, as may be seen from the accompanying table. The
thickness of C, was obtained, with some uncertainty on account of
faulting, only between Fall and Mewslade Bay; it probably les
between 280 and 350 feet.

Thicknesses in feet of Horizon y and Subzone C, in
South-Western Gower.

|

Laminosa Dolomites.

|
Lower) Upper |
y part. | part. | Total.) Caninza Oolite.| Total, y+C,.

eI ete oe 120 | 80 | 60 | 140 | 160 (at least) 420
Inner Head...) 185 | 115 | 90 | 205 | 180 470

The best exposures of Horizon y and C are (1) the Inner Head
islet, accessible for a limited time from the mainland by crossing
the rocky isthmus at low tide :—the whoie, except the top of C,;
(2) the cliff-top near Old Castle, Rhossili, where y has yielded the
fauna enumerated on p. 545, and the Laminosa Dolomites also are
seen; (3) Tears Point and the cove called ‘ Fall’ on the north :—
y and C,; (4) the fine range of cliffs* between Fali and the bluff
west of Overton Mere :—C, with much of S.

Seminula Zone,? 8.—This zone has almost the same facies as
in the Eastern District. The top appears, however, to be so lacking
in rock-types characteristic of Modzola phases, that it is separated
from the rest of 8,, not on its own merits, but for purposes of
comparison with the Modiola phase on this horizon in other areas.

The general sequence, which has been determined more exactly
than in Eastern Gower, is as follows, in descending order :—
S,i—

3. Modiola phase. Evidenced merely by occasional ‘ pisolites.’
The ‘ pisoliths’ outwardly resemble those which are so abundant in
the Eastern District, but include fragments of a Mitcheldeania-like
alga. True calcite-mudstones, such as ‘ chinastone-limestones,’ if

' Described by Dr. A. Strahan in the West Gower Memoir, pp. 12-13.

First recognized in this district by Dr. Gubbin & Dr. Vaughan, Proc.
Bristol Nat. Soc. ser. 4, vel. 1 (1905) pp. 44-50, 54-56.

Vol. 67.| THE CARBONIFEROUS SUCCESSION IN GOWER. 503

present, are rare; their place is, apparently, taken by limestones
that are rather less fine-grained and contain an abundance of
Calcisphera (?) and foraminifera. These rocks and the ‘ pisolites’
are interbedded with oolite like that of Group 2 below, their lower
limit being unknown but probably quite indefinite. Upwards the
change to Zone D with its characteristic fauna and sediments is
comparatively rapid, the highest bed definitely assignable to, being
separated from the lowest undoubted D limestone—the oolite
described on p. 504—by 24 feet of limestones of less determinate
relations.

2. Chiefly light-grey, thickly-bedded oolites, many sparingly
fossiliferous ; some fine-grained limestones, composed of current-
bedded organic detritus. At intervals occur dark, finely-crystalline
dolomites, up to several feet thick, which, though in some cases
markedly impersistent along the bedding, as already described by

Dr. Strahan (West Gower Memoir, p. 13), are inferred, from their

microscopic characters,’ to owe their alteration to the influence of
the Carboniferous sea. Near the base of the group the limestones
contain sporadic, light-grey sponge-cherts, of concentric, alternately
siliceous and calcareous zones. Thickness, including the Modiola
phase above, between 320 and 870 feet.

1. Gasteropod-limestones,” dark, highly bituminous, and well-
bedded; many of the gasteropods selectively dolomitized in the
way described on p. 484; cherts and beekitized fossils. Thickness
= 120 feet.

Si

2. Gasteropod-limestones, dark and continuous with those above,
but on the whole more thinly-bedded, and separated from one
another by soft shaly partings; highly fossiliferous (p. 547);
beekite in fossils in the upper beds; some beds more or less
dolomitized. Thickness =105 feet.

1. Limestones, similar to the underlying C, limestones; less
fossiliferous than the beds above; little dolomite and no chert or
shale. Thickness =115 feet.

The whole zone is exposed in the cliffs and shore near Port-
Eynon Point, from the bluffs at the cliff-foot, west. of Overton
Mere,’ where §, is finely displayed, eastwards to Sedgers Bank,
where D comes in. S, and 8, enter largely into the cliffs on the
west, also, of Overton Mere, as far as Mewslade Bay.

1 Similar to those of contemporaneous dolomites described in the Swansea
Memoir, pp. 16-20 & pl. i, fig. 4.

2 Included by Dr. Gubbin in S,; the absence of Caninia bristolensis Vaughan
has led to my placing this group in §,,.

3 Details from this locality, especially of the gasteropod-beds, are recorded
by Dr. Gubbin (Proc. Bristol Nat. Soc. ser. 4, vol. 1, 1905, pp. 44-50), who has,
however, greatly underestimated the thickness of S,; the ‘black calcareous
sandstone’ to which he refers on p. 47 is the dolomite in Group 2 of §,,
mentioned above. 1

——

504 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON [Nov. rg1rt,

Dibunophyllum Zone,’ D.—The important feature of this
zone in South-Western Gower is a strong development of D,, a
subzone which is unknown in Eastern Gower though present in
the North-Western District.

The facies of D, differs in no important respect from that observed
in Eastern Gower. An oolite, 7 feet thick, in part of the coarse
type usual at this horizon, lies at or near the base. Some of the
beds, including some pseudobreccias,” are dolomitized, the gastero-
pods showing the selective action previously mentioned.

In D, are placed the highest beds of the Main Limestone. The
change of fauna in passing from D, to D, is not accompanied by
any lithological change, so far as known, but pseudobreccias die
out some distance above. The upper part of D, consists of various
rock-types, including coarse oolite, coral-limestone, dark fine-
grained bituminous limestone with black chert, dolomite, and pale
limestone. Some of the latter occurs immediately below D,,,,
but is as pure as any other part of the Main Limestone, except
for an abundance of pale chert. The change to D,_., faunal and
lithological, is as rapid as in Eastern Gower.

D,_, is equivalent to the Upper Limestone Shales, which are
similar to the beds of the same name in Eastern Gower, except that
they include, interbedded among the argillaceous limestones and
shales, a few pure, pale limestones with chert, resembling some of
the D, limestones. The correlation with D,, of Eastern Gewer is
discussed on pp. 551-52.

The top of the zone and its relations to the overlying P beds are
not revealed.

The whole of D, and D,, 600 feet in all, and a thickness of at
least 150 feet of D,.,, the latter folded, and much reddened by
Triassic infiltration, crop out on the shore of Port-Eynon Bay.
Better exposures of much of D, and D,, with the faunas recorded
on pp. 548-49, are obtained in quarries in the plateau above Port-
Eynon Point; those in D, lie about a quarter of a mile south-
south-west of Port-Eynon church.

2-3?

Posidonomya Zone, P.—The development in this district is
probably the same as in other parts of Gower. Jadiolarian cherts
are believed by Dr. Strahan °* to crop out near Overton; and shales,
grey or raddled, with the fauna enumerated on p. 552, are exposed
in an old ‘ paint-mine’ at Port Eynon described by the same author
(loc. cit.). Black, evenly-bedded sponge-cherts do not appear to
be exposed in the mine in situ; but, to judge by fragments in
the overlying Triassic conglomerate, they do occur in the series.
A single band, a few inches thick, of shale studded with crinoid-
ossicles and now decalcified, emphasizes the rarity of such material
above the Dibunophyllum Zone.

1 First recognized in this district by Dr. Gubbin & Dr. Vaughan, Proc.
Bristol Nat. Soc. ser. 4, vol. i (1905) pp. 48-44 & 56.

2 These I described in the West Gower Memoir, p. 16, as ‘ without dolomite,’
whereas some only are undolomitized.

3 West Gower Memoir, p. 18.

eee tcneceelisniopepecenencetabvaneesnenticnereeeest eee eae Te eT

To face p. 508. |

Zone, Subzone
or Horizon.

Postmponouya
ZONE,

CLEISTOPORA ZONE

Devonian.

RB

s oF GOwER.

N orth-wil

|

less.

|
As in the Eastern district, appar’

r
ans

5 Cea Not known. 350 feet.
NX
s Tee > =: 4
: D, or D, _| D, :—Limestones. bt.
i airs eS :
Ss |
= D, Much as in the Eastern distri 459 foot.
S without dolomite.
2. Modiola Phase :—Calcite-mud

a S ‘ pisolites ’; standard limes

US Oy . . .
S : 1. Chiefly light-coloured oolit
S YW) dolomite known. be
= Re rape
= Rather dark limestones, with
2s S calcite- or dolomite-mudst

‘contemporaneous’ dolomit
chert.

S 2. Similar to 8), but without miet,
S C or dolomite.

2 2 1. Modiola Phase;—Much as |
Sake Kastern district.
gC
= C 2. Oaninia Oolite. ee
S 1 1 Laminosa Dolomites.

&

ZB a Not recognized,

eS]

z .

N Z, Sunilar to the Laminosa Dolom

or)

Fey vel :

ee

s Z, Much as in the Eastern district.

Ry

NS B Not recognized.

aa

Lower Limestone Shales :—2-4
shales with thin limestones; {
oolitic limestone, probably b
K, and K,

1. Modiola Phase, Km. Grey|
with ostracod-limestones ; lin
of a-type.

(Passage)

U

Se

han 50 feet.

As in the East¢

Much as in t
intercalated,
stones.

=

D, :—Coral-, oo
breccias ; che

Much as in the

3. Modiola Ph
among sta

1&2. Chiefly
cherts neai
limestones

2. Gasteropod-]
little cheri
1. Thickly - bec
dolomite. |

Similar to gro)
developed at

2. Caninia Ool
1. Laminosa
undolomit

Chiefly nodular
Limestones wit
part, to a h

Gower.

Se

Lower Limestq
but probably

1. Modiola Phi
shales; a

eS Ul Oe ee ae —C er rt ee eeer,,lmlrl mrt ee eermrmrmrtmltlcC ee.
t

Or

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 50

(4) Tabulated Synopses of the Sequence.

Table I embodies the chief features of the developments in the
three districts of Gower, together with the thicknesses, which are
also shown graphically in fig. + (p. 506). In both table and figure
the Eastern District is placed between the two others because, as
will be seen, it has relations with both. The differences between the
different developments, of which more will be said later, might
not be regarded as of importance, were it not that each development
could be matched elsewhere in the South-Western Province.

Table II embodies the features common to much or all of the
area, and may be regarded as typical of much of the South-Western
Province.

TasLE I].—Synopsis oF THE LITHOLOGICAL SEQUENCE IN GOWER AS A WHOLE
(GENERALIZED FROM TABLE I).

Zone or Subzone.

Pp 2. Chiefly dark non-calcareous shales.
| 1. Radiolarian cherts.

|

ae ‘ Black lias ’ :—soft-weathering, argillaceous limestones with
2~3 shales and cherts.

| D. D, or D,_, | Limestones, including pseudobreccias.
D Chiefly pseudobreccias ; thin coal? or coals.
S { | 2. Modiola phase, characterized especially by ‘ pisolites.’
Ss 2 | 1. Chiefly oolites. |
ay 2. Limestones of various types.
C,+8, | 1. Modicla phase,? characterized especially by abundant |
| calcite- and dolomite-mudstones.

Oe ie Caninia Oolite.
| iy 1. Laminosa Dolomites (replacements of crinoidal lime-
| | stones).

Fi: _Crinoidal dolomites and limestones; cherts near the base. |

2. Grey shales with thin limestones; a thick oolitic lime- |
1 K? stone, probably between K, & K,. |
| |1. Modiola phase, Km, characterized especially by ‘lime-

!
stones of a type.

'

' Devonian. | Upper Old Red Sandstone. |

Note:—K is equivalent, probably exactly, to the Lower Limestone Shales; the
sequence, Z to D, inclusive, is termed ‘ Main Limestone’ by the Geological Survey ;

D,_, is termed Upper Limestone Shales; and P is included with the Millstone Grit.

1 Not known in the North-Western District.

2 Not known in the South-Western District.

3 Not developed in the South-Western District.

4 K is best known in the North-Western District, but there is no reason to believe
that the development is different elsewhere.

(Quart. Journ. Geol. Soc., Nov. 1911.

To face }). 508. | |

Taste I.—Synopsis oF tae LirHonoGicaL Sr@uENcE IN DIFFERENT Parts or Gower.

Eastern District. South-Western District.

Zone, Subzone North-Western District.

or Horizon.

| Thickness. Thickness.
2. Chiefly dark, non-caleareous shales ; some} \¢ Jeast 1500 feet.
black sponge-cherts in the lower part. |
1. Radiolavian cherts with shales ; wavellite. Probably less than 650 feet.

———

Thickness.

As in the Hastern district, apparently. Unknown. As in the Eastern district, apparently. Unknown.

Posmonouya
Zone

| c a
— |
, i ‘Black lias’ :—soft- weathering, argillaceous Much as in the Eastern district, but with some ae
% D Not known. limestones and shales, with sponge-cherts and) Between 175 & 350 feet. intercalated,) non-argillaceous, cherty lime-| At least 160 feet.
S 3<8) some dolomite; wavellite near the top. | stones.
Beni ra a i. ae ; =| ie ae
= ? albnt ss than 300 fect, | Dy-» :—Limestones, including pseudobreccias ;| a D, :—Coral-, oolitic, and other limestones; pseudo- i - 200 fe
3 Dy or D, | D. :—Limestones. ( Probably less than 300 feet igilontin 8 P | At most 120 feet. breccias; chérts; dolomite. About 200 feet.
5] ated |
eit ala we eS 9 S| aaa
a 7 Pata a ‘hi ISD STAN ED en oll = Teer ;
5 D Much as in the Wastern district, but Chiefly pseudobreccias, generally dolomitic;) Between 400 & 450 feet. Much as in the Eastern district (coal not known).| About 400 feet.
FS 1 without dolomite. ‘pitted’ surfaces ; thin coal with underclay.
— be ||
2, Modiola Phase:—Calecite-mudstones; | Modiola Pliase :—Calcite-mudstones ; * pisolites’;} 3. Modiola Phase <—Poor; a few! © pisolites :
3 ‘<olites’: standard limestones standard limestones; dolomite. among standard limestones ; dolomite.
§ Y ps; Standar ey ae | | et 5 6 : q
z 5, Dea ie : Tites ; 1&2. Chiefly light oolite with zoned sponge-| -About 1000 feet.
S 2 1. Chiefly light-coloured oolites; no | cherts near its base; some cherty gasteropod-
y dolomite known. | | At most 800 feet. The development of S up to the Modiola Phase {About 1260 feet. limestones below ; dolomite.
py __y_ ee | is much as in the South-Western district. || ae ae = a aa
SI Rather dark limestones, with|a rare | 2. Gasteropod-limestones ; shaly partings and a
bat belt : i || little cher} ; dolomite. ,
at GQ calcite- or dolomite-mudstane ox b | 220 feet.
! ar “contemporaneous” dolomite ; no 1. Thickly- bedded, pale limestones; little
chert. dolomite.

——— enn ee

a 2, Similar to S), but without mndstone | Between 230 and 280 tect. | 2. Much as in the South-Western district. 200 to 350 feet. any
6 G or dolomite. | Similar to group 1 of S). (No Wodiola Phase} Probably between 280
> 2 1. Modiola Phase;—Much as in the | 45 feet. 1. Modiola Vhase (wanting at Longland Bay) :— 3 deyeloped)at ithe base.) & 360 feet.
a Hastern district, | Chiefly calcite-mudstones ; dolomite. 16 to 20 feet.
| oO = = — — and oe — , SS een —————— —_
B t ae: 5 100 feet. 2. Caninia Oolite. \ 70 to 160 feet. 2. Caninia Oolite. 130 to 160 fee
_ 2. Caninia Oolite - : +e : 160 feet.
g C : a ie Walowites > 1. Laminosa Wolomites; few wndolomitized} ) 1. Laminosa Dolomites, the lower part half
a “ 1) Lamnosa Molomires: (crinoidal) limestones. | unidlolomitized ; occasional cherts. 140 to 200 feet.
wn y Not recognized, | Not recognized. Chiefly nodulai, argillaceous limestones. 120 to 135 feet.

| Sanna 320 feet.

| eo | = —V—
E : | Limestones with dolomites; cherts in the lower
N Z, Similar to the Laminosa Dolomites. About 520 feet. Similar to the Zaminosa Dolomites. |
4 | J part, to a higher horizon than elsewhere in NE TeAgH BHO feet
Bi 5 Se) es =e | | = = = east 530 feet.
gN Z, F . Spee | Dolomites, with crinoidal limestones in the lower Gower.
5 , Much as in the Eastern district. part; cherts towards the base. 150 feet
q “ | : > 150 feet.
N Not recognized. J Crinoidal limestones. J Not recognized.
Fe Ee
E Lower Limestone Shales :—2-4. Grey
aS shales with thin limestones; a thick Lower Limestone Shales:—2—4. Little exposed,
§ oolitic limestone, probably hetween 1 | Between 400 and 500 feet. Provably the Lower Limestone Shales, which are! ; but probably as in North-Western Gower. Unknown.
£m Ky and K, | 1¢ barely exposed p Unknown.
S | arely e3 5
5 2
a 1. Modiola Phase, Km. Grey! shales | ; z ne
& with ostracod-limestones; limestove | 1. Modiola Phase, Km. Chiefly grey ostracod-
& of actype, s | shales ; a quartz-conglomerate. Unknown,
BUS S26
Devonian. Upper Old Red | Sandstone.

Fig.4.

Comparative Vertical Sections
through the

Avonian of Gower.

3
=
§
S
Bue
3
™_
wH
S
~ ae Radiolarian cherts
‘Ss D
sO
2 D,
Q

Se

Seminula
S

ie

Co

© Modiola-phase | FSS] ">
Caninia |°_o
Oolite
Laminosa
Dolomites

C;

VE

i Zaphrentis | Syringothyris

on a oe a eee

Chiefly
shales;
thickness

unknown.

Cleistopora
K

Thickness

DEVONIAN

Ne ae [Where, from any cause, the position of a ‘ unknown.
Sandstone) zonal boundary has not been determined si
exactly, it is shown as a broken line.] “
Km

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 507

III. Nore on tHE PsEupOBRECCIAS OF THE D-Zonn

ee EE Dal

_ The following observations relate to the pseudobreccias of Gower,
where these rocks are peculiar to the Dibunophyllum Zone and
at that level are extensively developed. While to some extent
supplementing Mr. Tiddeman’s description,’ this note deals more
particularly with the question of origin, which is of interest on
account of the resemblance of the rocks to true breccias, and also
because other nodular, foraminiferal limestones, such as some of the
bands in the Chalk, may owe their structure to the same cause. It
may be mentioned that the explanation of the structure of pseudo-
breccias. here advanced, has suggested itself to Mr. J. A. Howe
also, in the course of a comprehensive study that he is making of
these and other limestones.

The structure in question, the outward appearance of which may
be gathered from Pl. XX XVIII, fig. 2, appears at first sight to be
due to the incorporation of angular fragments of rather dark lime-
stone, of various sizes up to a diameter of several inches, in a
ground-mass which is limestone in some places, and dolomite in
others, but is always lighter in colour and more argillaceous than
the ‘ fragments,’ * sometimes markedly so. The greatest contrast is
presented where the ‘ground-mass’ is dolomite, as the latter forms
a rather coarsely-crystalline, pale-grey mosaic.2 We may first,
however, consider the undolomitized examples.

‘Fragments’ and ‘ground-mass’ vary in their relative proportions,
but as a rule are approximately equal, and the latter occurs
characteristically as meandrine tracts enclosing the former. In no
pseudobreccia has it been possible to distinguish bands differing
one from the other in the size or abundance of their included
‘fragments.’ ‘The same fauna, a standard marine assemblage,
is found in the ‘ fragments’ as in the ‘ ground-mass.’

Microscopic examination shows that the matrix of the fossils in
both ‘fragments’ and ‘ ground-mass’ is a consolidated ‘mud,’ con-
sisting essentially of finely-divided calcite and containing, as a
rule, a notable quantity of foraminifera.* Furthermore, such
examination shows that the outlines of the ‘fragments’ are not
sharp and well-defined-like those of true fragments, but that
their matrix shades off into the matrix of the ‘ground-mass.’
On this account largely, and also in view of other considerations
which will be adduced, it is inferred that the rocks are not

1 Swansea Memoir, p. 10.

2 See analysis by Mr. E. G. Radley, Swansea Memoir, p. 13.

3 A dolomitized example is figured in the Swansea Memoir, pl. i, fig. 1.

4 The following have been identified in microscope-sections by Dr. R. L.
Sherlock :—‘ Callencroft Quarry, Mumbles [E 5000]: very rich in foraminifera,
chiefly Endothyre, such as Endothyra bowmani Phillips, Endothyra sp., and
Textularia sp. (either gibbosa d’Orb. or eximia Eichw.).—Oxwich [E 5001]:
Endothyra sp. (small form).’

Q.J.G.8. No. 268. Qn

508 MR. E. E, L. DIXON AND DR. A. VAUGHAN ON [ Nov. 1911,

really fragmental. Ultimately, doubtless, they owe their structure
in part to their composition,! but the proximate cause of it alone
concerns us here.

Before passing to this subject, however, it should be remarked
that Dr. Hume connects the nodular structure of parts of the Chalk
with current-action.*” A complete comparison of nodular chalks
with pseudobreccias has not yet been made, but it is known that
some of the former closely resemble the latter. It is possible that
in the clay with limestone-rubble, into which occasional pseudo-
breccias pass laterally (p. 490), the rubble, which resembles the
‘fragments’ of pseudobreccias proper, but is sharply separable from
its clay-groundmass, has been more or less rearranged by currents,
after originating in a patchy recrystallization (and segregation) of
calcareous mud in the manner presently to be described. There is
no reason, however, to believe that the ‘ fragments’ in the pseudo-
breccias proper have also been washed up and redeposited; and it
remains to be seen whether all nodular chalks show evidence of
current-action, or whether some are not pseudobreccias.

As contradicting the view that the ‘fragments’ in the Gower
pseudobreccias are derived, and have been incorporated in their
present condition, may be adduced the fact that occasionally
some are continuous one with the other and partly enclose ‘ ground-
mass, thus losing their resemblance to fragments. It may be
suggested, however, that the ‘fragments’ in these rocks are true
fragments of contemporaneous sediments, which, unrecrystallized
at the time of their incorporation, have lost all trace of their
limiting surfaces through later recrystallization of themselves and
some of the surrounding ground-mass. Apart from the absence
from the pseudobreccias of any sign of current-action in either a
sorting or a banding of their constituents, no evidence of a truly
fragmental origin has been detected in any of the numerous ‘frag-
ments’ that have been examined, and the suggestion takes no
account of the fact that, so far as known, the pseudobrecciated
structure is confined to foraminiferal limestones.

To turn to the proximate cause of the pseudobrecciated structure,
the features whereby the matrix in the ‘fragments’ differs from
that in the ‘ ground-mass’ are, in addition to its less argillaceous
character, mentioned above: (1) that it is invariably rather more
crystalline, though still fine-grained and obviously a slightly re-
erystallized mud; and (2) that it is often, possibly always, more
foraminiferal. Both features are iliustrated by Pl. XXXIX, in
which, indeed, hardly any foraminifera are seen in the dense
‘eround-mass.’ (The ‘fragments’ are the hight areas with irregular
boundaries along the top, bottom and left-hand margins of the field.)

1 Rocks similar in structure to the pseudobreccias of Gower are known in
other regions, in the same and in other formations, but all appear to be
foraminiferal. Many foraminiferal limestones, however, are not pseudo-
breccias, whence it is obvious that other conditions, besides a suitable com-
position, have been necessary for the production of the distinctive structure.

2 Proc. Geol. Assoc. vol. xiii (1894-95) p. 230.

_ ?

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 509

Confining our attention at present to the first feature, it is
concluded that a muddy matrix has undergone partial recrystal-
lization, as it were into irregular clots, and thus, by differentiation,
quite possibly from a homogeneous state, given rise both to the
‘ fragments ’—the recrystallized parts, and the ‘ ground-mass ’"—the
less crystalline residue. This local recrystallization is inferred, for
several reasons, to have taken place shortly after the deposition of
the mud. Its peculiar patchiness, in which it differs strongly from
late recrystallizations, and its widespread occurrence on the same
horizon (D)* are most readily explicable on this view. Probably
the best reason, however, is that, in Gower, as we shall see, many
pseudobreccias have been dolomitized after recrystallization—but
while still within the influence of the Avonian sea”; such a view
postulates an early age for the recrystallization. The latter, there-
fore, appears to be analogous to the early recrystallization known
to affect recent calcareous muds,’ but why it assumed a patchy
character is unknown.

The other features of the pseudobreccias would result directly
from a patchy and early recrystallization of a calcareous mud.
Recrystallization implies deposition of calcite, and would probably
be accompanied by segregation of that mineral and, in a still soft
matrix, extrusion of impurity into the unrecrystallized parts. This
action would account for the excess of argillaceous matter in the
‘oeround-mass.’ Furthermore, delicate calcareous bodies like
foraminifera would tend to disappear from the unrecrystallized
parts, to balance, by their dissolution, the deposition of calcite in
the recrystallizing areas.

But, whatever be the ultimate nature of the ‘fragments,’ their
more coarsely crystalline structure in comparison with the ‘ ground-
mass’ has given rise to secondary features of much interest.
They appear darker in hand-specimens, on account of their greater
translucency. Again,—and this is of far more importance,—they
offer a greater resistance to chemical change than the ‘ ground-
mass,’ in accordance with the general rule that in calcitic rocks
such resistance is proportional, ceteris paribus, to the coarse-
ness of the crystalline structure. The difference is shown in a
variety of ways. The ‘fragments,’ which may be almost invisible
on a fresh surface, often project boldly on weathered faces.
Occasionally, it is found that the ‘ ground-mass’ has recrystallized
at some late date completely to coarse calcite-mosaic, but the
‘fragments’ included in this mosaic are still unaltered. The
difference, however, between the two kinds of material is shown
most conspicuously by the difference in their susceptibility to

1 Pseudobreccias are frequent in D, not only in Gower but also in many
other areas both within and without the South-Western Province.

2 This view as to the age of the dolomitization is based not only on the
original evidence cited in the Swansea Memoir, p. 14, but also on various facts
which have come to light since.

3 See, for instance, E. W. Skeats, Bull. Mus. Comp. Zool. (Harvard) vol. xlii
(1903) pp. 105-18, figs. 2 & 4-6.

2QnQ2

510 MR. E, E. L. DIXON AND DR. A. VAUGHAN ON [Nov. 1911,

dolomitization by the waters of the Avonian sea. (Dolomitization
due to clearly-later percolation, it may be noted in passing, has
affected both materials equally.) In fact, the difference between
the ‘ ground-mass ’ and the ‘ fragments’ in this respect is so great as
to suggest that at the period of dolomitization the former was still
unconsolidated and readily permeable, as well as more unstable.
In many pseudobreccias and for long distances in them it has
been completely altered, though, as a rule, the whole of the enclosed

Fig. 5.—Diagram showing the relation of the dolomite, in a partly
dolomitized pseudobreccia, to unrecrystallized calcite (see p. 511).
Natural size.

[a, a represent ‘ fragments,’ consisting of recrystallized calcite; 0, 6, tracts of
‘oround-mass,’ consisting of unrecrystallized calcite; and e, ¢, dolomite.
The limit of the dolomite is generally sharp against the ‘fragments,’
but against the unrecrystallized calcite it is too indefinite, as a rule, to be
shown properly in a diagram. |

‘fragments’ have been but little affected. It has thus, by deter-
mining the paths of dolomitization, led to a marked accentuation
of the pseudobrecciated structure. In many dolomitized pseudo-
breccias, as in the example figured in the Swansea Memoir, pl. 1,
fig. 1, the ‘ground-mass’ has been so completely replaced by
dolomite-mosaic in which its proper structures have been lost, that
the original nature of the material replaced by the dolomite would
be open to doubt, were it not that in other such pseudobreccias
dolomitization has been incomplete, and wholly absent from parts

Vol. 67.| THE CARBONIFEROUS SUCCESSION IN GOWER. dll

of others again. The latter, one of which is represented diagram-
matically by fig. 5 (p. 510), show clearly that the paths followed by
the dolomitization have been the tracts of unrecrystallized ‘ ground-
mass. Pl. XXXIX, taken from the junction of a dolomitized with
an undolomitized portion of a pseudobreccia, shows that the dolomite
has developed freely in the dense ‘ ground-mass,’ partly as isolated
rhombohedra, partly as a band of clustering crystals, but that it has
been excluded from the more crystalline ‘fragments.’ (The dia-
gonal cross seen in many of the rhombohedra is probably due to
inclusions of the argillaceous impurity in the ‘ ground-mass.’)

Dolomitized pseudobreccias, such as that figured in the Swansea
Memoir, resemble true breccias more closely than do the unaltered
rocks, owing to the great contrast in them between the sharply-
defined ‘fragments’ of dark, fine-grained limestone and the en-
veloping pale-grey, rather coarsely-crystalline dolomite. Also,
their structure is more conspicuous, whether on unweathered faces,
or in cliffs, where they often become cavernous through the
dissolution of their ‘fragments.’ Consequently in Gower, where
they abound along the southern coast, they have attracted more
attention ; but, as we have now seen, their dolomitization has not
been the primary cause of their peculiar structure—it has merely
brought into prominence an earlier recrystallization.

LV. Nore on Lagoon-PHAsEs AND THE ORIGIN OF RADIOLARIAN
Cuerts [E. E. L. D.].

(1) Introduction and Definition.

By a lagoon-phase is meant a group of rocks, the characters
and development of which show that it has been deposited in a coastal
area, of wide extent both parallel and at right-angles to the coast,
but so extremely shallow as to have been, in effect, isolated from the
neighbouring though deeper parts of the sea, and thus to have
become the site of peculiar types of sediment and fauna.!

A lagoon-area as thus defined is shown in section, at right angles

1 Tt has been thought better to adopt the word ‘lagoon’ and to speak of
such an area as that defined above as a lagoon-area, rather than to coin a new
expression, because the conditions obtaining in lagoons, as defined in the
‘Century Dictionary’ (London, 1899), must approximate closely to those
which it is desired to connote. According to this authority, a lagoon is
primarily ‘an area of shallow water, or even of marshy land, bordering on
the sea, and usually separated from the region of deeper water outside by a
belt of sand or of sand-dunes, more or less changeable in position.’ Though
there is no evidence that subaérial barriers, such as dunes or coral-reefs, have
existed in the case of the lagoon-areas with which we shall deal, possibly because
the chances are against their having been preserved, exposed, and correctly inter-
preted, they are evidently not essential features of lagoons. Further, several
formations which are lagoon-phases as above defined, such as the Solenhofen
Slate, are described by Prof. J. Walther and others as having been deposited in
shallow lagoons.

Fig. 6.—Ideal section across a lagoon-area, at right angles to the coast.

[The slopes throughout, both terrestrial and submarine, are exaggerated. |

Open Sea

Lagoon-area

IL5 gl, im (al

Sea-Level

to the trend of the © coast, im
fig. 6. Lagoon-phases are regarded
as coastal deposits, and the lagoon-
area, consequently, is shown in the
figure as a coastal shelf, for reasons
which appear later (pp. 525-28).
The area is represented as bordered
by rapidly deepening water, to accord
with the general profile of recent
coastal shelves.

That extremely -shaliow marine
areas, such as are here postulated,
have formerly existed is beyond
question, for the deposits in some
cases may be interpreted without
hesitation. Under the names of
‘Modiola and Posidonomya phases ’
some of these deposits, of Avonian age
and calcareous facies, have already
been described by Dr. Vaughan,"
and the object of this note is, partly
to bring out the distinctive cha-
racters of these phases, partly to ex-
tend the concept to rocks of cherty
facies. | Lagoon-phases, therefore,
would include both Modiola and Po-
sidonomya phases and equally shallow
deposits of other ages and facies.

But, although lagoon-areas have
undoubtedly existed, it is probable
that their extreme shallowness and
wide extent together would not
sufficiently account for the general
absence from them of strong currents,
which, as we shall see, has been
their distinguishing feature. Appa-
rently the rise and fall of the tide,
which, if considerable, would inhibit
lagoon-conditions on an open coast,
has been either so small as to be
negligible, or has been rendered
inoperative by subaérial barriers,
which may have included thickets of
vegetation such as those of mangrove-
swamps, along the margins bordering
deeper water.

' These are tabulated by him in Table IT
of his report on the faunal succession in
the Avonian, Rep. Brit. Assoc. (Winnipeg)
1909, p. 190; reference will presently be
made to his description of the development
of these phases in the Avon section.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 513

(2) The Modivla Phases—Calcareous Lagoon-Phases—
of Gower.

Introduction.—The Carboniferous succession in Gower in-
cludes four lagoon-phases, namely, Km at the base of K, the base
of (C,+8),’ the top of §,, and the radiolarian cherts at the
base of P. The chief features of each of the first three, which are
calcareous in facies, are set out in Tables III & V (pp. 514 & 526),
the deposits characteristic of shallow waters being distinguished
from intercalated ordinary sediments where, as is generally the
ease, the latter exist. ‘The fourth phase, which differs from the
others in being eherty, will be discussed separately, as an origin
at a totally different depth has been ascribed to rocks elsewhere
possessing closely similar characters. All four phases have been
recognized at other places in the South-Western Province and
some of them elsewhere also; the information in the tables con-
cerning the Bristol area has "been extracted from Dr. Vaughan’s
accounts,” and that about Pembrokeshire has been obtained during
the progress of the Geological Survey. No attempt, however,
will be made to give full particulars of the geographical extent
of any phase.

Distinctive features of the Modiola phases.—We may
now learn from Table III in what way Modiola phases differ from
ordinary marine formations; from the interpretation of their
distinctive features, which will follow, it will appear why they
may be styled ‘ lagoon-phases.’

On the one hand, ali the Gower Modiola phases exhibit, at one
place or another, but not necessarily everywhere, unmistakable
shallow-water characters which are shown to some extent, also,
by ordinary shallow-water deposits (Table III, 1&2). In the
first and third phases there are, likewise, many intercalations of
ordinary rock-types (Table III, 4), due to the interruptions of
lagoon-conditions by more normal ones mentioned on p. 518.

On the other hand, they all include, also, one or more rock-types
(Table III, 3) which, in a fairly shallow-water marine series, such
as the Avonian, are confined either to Modiola phases or to merely
occasional beds in the shallow-water parts of the sequence. Some
of these distinctive rock-types (namely, limestones of a type and
purple and green shales) appear to point directly to deposition in
shallow, isolated, coastal areas, and, therefore, will be considered
first; the other group to be discussed here—mudstones and shales
characterized by an exceedingly fine grain,—which is far more
important than the first group on account of its more general
occurrence, resembles, rather, deep-sea deposits.

‘ By this expression is meant the group consisting of subzones C, and =F

* Q. J. G.S. vol. Ixi (1905) p. 181 (cited thus: ‘ Bristol paper,’ Pp. -=1)3
and, in the case of the Avon section, Soe Bristol Nat. Soc. ser. 4, vol. i (1906)
pp. 74-168 (cited thus: ‘ Avon,’ p.

3 «The Country around fe dee and ‘ The Country around Pembroke’
(Mems. Geol. Surv.) ; in preparation.

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Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 518

Limestones of a type.—Limestones of a type, named after
the well-known Bryozoa Bed, Horizon a,’ of the Avon, consist largely
of crinoid-ossicles and dendroid bryozoa, broken and rounded by
rolling and reddened with hematite. Hematite may appear, also,
in the matrix and in the coatings of ooliths, but the characteristic
feature of the rocks is the relation of the iron-oxide to the
fossils; it infills organisms, such as bryozoa, that
possessed open cavities, and picks out the trabecular
structure of the crinoid-ossicles.*

The significance of limestones of a type lies in this—that their
distribution and lithological characters, details of which are reserved
for another communication, all point to the conclusions that they
have received their iron-content (apart from secondary enrichment)
at the time of their deposition, and that the iron-compound has
been, from the first, in the condition of oxide and probably, as now,
in that of hematite. These views, though differing directly from
those of Prof. Cayeux as to the origin of a Devonian (Eifelian)
heematite from the Ardennes which has the characteristic structure
of limestones of a type,” are in full agreement with the conclusions
of C. H. Smyth, Junr.,* and others’ regarding the period of intro-
duction and primary nature of the hematite in the well-known
Clinton (Silurian) iron-ore of the United States, an ore that also
contains a quantity of rolled bryozoan and crinoidal débris, infilled
and picked out with hematite.

The contemporaneous deposition, in a sedimentary formation
unassociated with igneous rocks, of a considerable quantity of an
iron compound,—and especially of hematite, if that were the
original condition of the iron-ore,—appears to be incompatible
with open-sea conditions and to demand comparative isolation and
proximity to Jand. Limestones of « type are, therefore, directly
suggestive of deposition in isolated, coastal areas®; but, at tlie
same time, their fauna, which consists largely of standard forms,
and the broken and rolled state of their constituents, indicate
conditions which, though shallow, depart from those—of abnormal
fauna and gentle sedimentation, as we shall see—most charac-
teristic of lagoon-phases.

Purple and green shales.—Purple and green shales that owe
their colour to conditions of deposition are of much more restricted

Described by A. Vaughan, Proc. Bristol Nat. Soc. ser. 4, vol. i (1906) p. 99.
See a microphotograph of a limestone of a type in ‘The Country around
Newport’ Mem. Geol. Surv. 2nd ed. (1909) pl. fig. 1.

* + Les Minerais de Fer Oolithique de France’ fase. i (1909) pp. 225-26:
the structure in quesion is beautifully figured in this volume. I am greatly
indebted to the courtesy of Prof. Cayeux for the use of some of his material.

* Zeitschr. f. prakt. Geol. vol. ii (1894) pp. 304-13.

° For instance, E. F. Burchard & E.C. Eckel in ‘Iron Ores, &e. of the
Birmingham District, Alabama’ Bull. U.S. Geol. Surv. 400 (1910) pp. 28 & 40.

6 This view, also, agrees with that of the American observers mentioned
above, who regard the Clinton ore as deposited in shallow bays and laguons
(see, for example, op. supra cit. p. 40).

=
i
»

516 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON ={ Nov. 1911,

occurrence in the Avonian than the preceding rock-type, being
recorded only from Km in a few localities. Their unusual colour
points to deposition in comparative isolation. Furthermore, the
fact that in other formations they are often associated with con-
tinental deposits suggests proximity to land; but it remains to be
seen whether they have been formed under other conditions of
isolation as well.

Calcite-mudstones and similar rock-types.— The
second of the groups of reck-types distinctive of Modiola phases 1s
much more widespread than either of the preceding types; its
members occur in all such phases as are known and at many
places in each. They are compact’ limestones, dolomites, and
argillaceous rocks which, under the microscope, are seen to be com-
posed, essentially, of exceedingly fine-grained, calcareous (that is,
either calcitic or dolomitic), argillaceous, and siliceous material, and
evidently represent, in most cases at least, consolidated muds* of
various compositions. For this reason, the caleareous members will
be spoken of as calcite-mudstones or dolomite-mudstones,’® in order
to distinguish them from limestones or dolomites of standard types
The calcite-mudstones include the rocks known as ‘chinastone-lime-
stones,’ so called because their compactness and white weathered
surface impart to them a porcellanous appearance. Most of the
rocks are evenly bedded, but some have concretionary forms. The
calcite- and dolomite-mudstones are either homogeneous and more
or less conchoidal in fracture, or are laminated and present a slabby
or platy fracture ; the lamine, which, in places, are extremely thin,
are either persistent or lenticular—wedge-bedded on a minute
scale. The homogeneous and the laminated types are equally fine
in grain. Similarly, the argillaceous rocks may be either clay-mud-
stones,—rocks to which the term ‘ mudstone ’ is ordinarily applied—,
shales, or paper-shales. Under the microscope the bedding in the
case of the laminated mudstones, calcareous or otherwise, is clearly
shown, even in the absence of fossils, by the layers, which differ
greatly one from the other in composition and appearance ; but in
sections of the non-laminated mudstones it cannot, as a rule, be
made out without the help of fossils. Where largely calcareous,
such mudstones might be taken for travertine ; but that they have
been deposited in the form of mud, whether detrital or chemically
precipitated, is shown by the fact that, where the material has partly

1 That is, amorphous-looking, and, in fact, often called ‘amorphous ’ though
the constituent grains possess crystal-structure.

2 This statement is based on an examination, still in progress, of various
limestones and dolomites that occur in Modiola phases. It remains to be seen
whether it is universally true of the compact layers; in some cases, as, for
example, that of landscape-marbles, an origin as travertine by direct accretion
from solution has previously been suggested.

8 It is possible that the dolomite-mudstones are calcite-mudstones dolomitized
without change of structure, but the balance of evidence at present available
suggests that they have been deposited as dolomite-mud.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 517

filled a hollow fossil, its surface against the residual space, originally
empty, is flat—in fact, a bedding-plane.

Those mudstones in which calcite or dolomite is predominant are
the most important, because they differ conspicuously from rocks
formed under standard conditions. It is true that standard lime-
stones frequently contain a considerable proportion of calcite-mud,—
so far dolomite-mud has not been detected in them ; included with
it in such limestones, however, are the remains of open-sea
organisms, for example, crinoids, brachiopods, and corals. Lime-
stones which are simply hardened calcite-muds, or contain merely
the forms enumerated opposite ‘1. Shallow-water characters’ in
Table III (p. 514), appear to be confined in marine series to the
distinct groups of strata (Modiola phases) under discussion, or, if
found among standard deposits, to an occasional occurrence in
shallow-water formations.

For the origin of the calcareous portion of the muds we do not
need to look beyond the detrition and disintegration of organisms,
both within and without the area of actual deposition, and also, to
some extent, of contemporaneously-formed ' limestones (oolites, etc.)
and dolomites, fragments of which are found in the interbedded
breccias. It is possible, however, that some, or even much, of the
mud has been chemically precipitated. But, in any case, the
uniform fineness of grain,—which characterizes the intermingled
terrigenous material also,—compels a conclusion of much im-
portance, namely, that the sedimentation of the mud-
stones was exceedingly gentle.

Conditions of deposition of the Modiola phases.—
Hence we see that the notable feature of the Modziola phases repre-
sented in Gower is in each an anomalous association of characters.
On the one hand, some of the latter indicate deposition in shallow
water: in fact, signs of marked current-action, such as the inclusion
of contemporaneous fragments, are to be found, in most localities,
at some part of each phase. On the other hand, the texture of the
rocks affords repeated evidence of the gentlest sedimentation.

The explanation of the anomaly is to be sought in peculiar con-
ditions of deposition. It is conceived that, as the area of deposition
of each phase was shallow, and extended far, both parallel and at
right angles to the Avonian coast (Table V, p. 526), under certain
circumstances the outer part of the area would protect the inner from
waves and strong currents, even in the absence of subaérial barriers
along the outer margin,—and of the existence of such barriers, as
previously mentioned, we have no evidence. The necessary attendant
circumstances would be that tides were at a minimum—to which

‘ Some of the mud may have been derived in part from older limestones
also, but to an extremely small extent, probably, as regards material deposited
in Gower; the phase in C,+S, may, however, owe more of its materiai to
such sources in those parts of the South-Western Province where it rests upon
older Avonian limestones unconformably.

518 MR, E. E.L. DIXON AND DR. A. VAUGHAN ON [Nov. 1911,

condition a steep slope of the sea-bottom down from the shallow
area would be favourable—, and that the shallowness of the sea
was extreme.

In other words, each phase was deposited in a shallow area of
sufficient extent to constitute, under conditions of minimal tides and
excessive shallowness, a great series of lagoons as defined in the
footnote on p. 511. In such a lagoon-area the pools would catch
the finest material, both that of local origin and the part that was
brought into the area from various sources outside,’ and there
watted about by gentle currents. Slightly stronger currents would
lead to the washing-up and incorporation of fragments of con-
temporaneous sediments ; and the area would be hable to invasion
at times by waters depositing standard rock-types. Such invasions
might result either from some deepening of the whole lagoon-area,
or from the temporary demolition of a bar—whether subaérial or
merely submarine. At other times, local emersion would probably
occur and be followed by cracking of the mud. In this way the
brecciation in set may have arisen.

Further, as some such conditions of deposition as are here outlined
alone explain satisfactorily the whole of those lithological features
of the Gower Modiola phases that are discussed above, we con-
clude that the strata of these phases have been deposited under such
conditions and are, accordingly, representative of ‘lagoon-phases.’

Landscape-marbles and ‘pisolites..—Some remarkable
rock-types, however, which appear to be confined to Modzola phases,
do not receive complete explanation, although their features are
not inconsistent with genesis in a lagoon-area; consequently
their discussion is deferred. Of these rock-types the chief may be
called ‘landscape-marbles,’ as they reproduce the essential features
of the Rhetic bed of that name, itself part of a Modiola phase.
Landscape-marble is conspicuous in the top of S,, the so-called
‘concretionary beds,’ in the neighbourhood of Bristol and elsewhere ;
and one of its features is developed on a minute scale at the base
of C, in North-Western Gower. The so-called ‘ pisolites’ of C, and
S, must have also required for their formation special conditions
as well as shallowness.

Faunal characteristics of the Modiola phases.—The
lagoon-area concept bears the same relation to the faunal peculiari-
ties of the phases as it does to the lithological features; it explains
most of them, and accords with the rest. The mudstones, which must
be regarded as deposited under conditions of greatest isolation, are
also most restricted in their faunal contents, being in many cases
unfossiliferous, and in most of the others yielding, whatever be their
horizon, only a special, phasal fauna, Of this fauna the members
of most general occurrence are certain lamellibranchs, especially
Modiola and Sanguinolites, Spirorbis-like annelids, as also ostracods

1 The colouring-material of the purple and green shales and of the lime-
stones of a type almost certainly came directly from the land, but much other
mud, ineluding part of the calcite, may have entered from the seaward margin.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 519

and Calcisphera (?) in abundance; but at many places one or
two members only are found. The lack of standard fossils in
the mudstones is striking in the case of the phases that we are
considering: for the latter occur in a formation, the Avonian,
dominated by crinoids and other open-sea forms. A few mud-
stones, however, as, for instance, some at the top of S,, contain
many individuals (though but few species) of brachiopods, especially
Seminula, that lived under standard conditions also. Again, the
proximity of the postulated lagoon-areas to the open sea with its
abundant fauna, and their liability to invasion, account for the
abundance of standard forms in the intercalations of ordinary
rock-types, which are frequent in some phases (Km and the top of 8,).
The 8, ‘ pisolites,’ also, have been laid down in disturbed waters,
and yield an ordinary marine fauna. It may be noted that, in
the phase in C,+8,, intercalations yielding open-sea forms are
extremely rare.

The phasal fauna is essentially shallow-water, but its poverty
and peculiar nature demand for full explanation something more
than mere shallowness. The isolated position in which the mud-
stones must have been deposited—whether separated from deeper
water simply by extensive shallows or by actual barriers—would be
favourable either, under certain circumstances, to an increase of
salinity, or, near a river, to a freshening of the waters. In either
case much of the standard fauna would be excluded. Some
ostracods, like their modern representatives, doubtless could endure,
and even thrive under, such adverse conditions. The same appears
to have been true of other organisms also. Thus, although lagoon-
conditions would favour the accumulation of plankton, including
Calcisphera(?), simply on account of its ease of transport from
the open sea outside the lagoon-area, the fact that some of the
calcite-mudstones contain an abundance of Calcisphera(?), but
fewer or no foraminifera, whereas standard Avonian limestones
(including those deposited in shallow water) yield these two groups
of organisms in inverse ratio, suggests that Calcisphera(?) throve
in the lagoons.

But, whether due to more than mere shallowness or not, the
characteristic feature of the calcite-mudstones, the most distinctive
rocks of the calcareous lagoon-phases of Gower, is barrenness or a
peculiar fauna, rich in individuals but not in species, which, though
but poorly represented in intervening standard deposits, is re-
markably recurrent, as regards genera and wider groups, in different
phases.

(3) The Radiolarian Phase—Cherty Lagoon-Phase—
of Gower.

Modes of origin of radiolarian deposits.—The fourth
lagoon-phase, that at the base of P, consists of radiolarian cherts
with interbedded, laminated shales which have yielded a few
lamellibranchs and plant-fragments. As, however, many radio-
larian rocks have, in consequence of the classic work of Dr. G.

520 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON’ | Nov. 1911,

J. Hinde, been regarded as deep-sea deposits (on account of their
exceedingly fine-grained texture as well as the abundance of
radiolaria in some recent deep-sea deposits), before proceeding we
must show why we conclude that the Gower cherts, which are
similar in both fauna and texture, have been formed under
diametrically different conditions. This is the more necessary,
on account of the weight attaching to the opinion of Dr. Hinde, as
well as the importance of the further conclusions based by other
geologists on his work.

The way has been prepared by many. observers, who have shown
that radiolarian rocks have not necessarily been deposited at the
depths at which the radiolarian oozes above-mentioned are found ;
in the case of some there is strong evidence of a shallow-water
origin. Thus, at Garn-bica in Carmarthenshire, on the same
horizon as the Gower cherts similar rocks have been found by
Mr. T. C. Cantrill and described by Dr. G. J. Hinde! which,
though of finer grain, if anything, than the Gower cherts, may be
inferred to have been deposited in shallow waters, on account of their
occurrence as a thin, conformable group between two shallow-water
formations—the Rottenstone Beds at the top of the Carboniferous
Limestone below and the Millstone Grit above.

As may be gathered from the conclusions of Dr. Hinde &
Mr. Fox as to the conditions of deposition of the Lower Culm
radiolarian rocks of Devon,’ of Prof. David & Mr. Pittman in the case
of the similar Devonian rocks of New South Wales,’ and of others,
as well as from a remark of Prof. Watts in discussing the Australian
example (op. cit. p. 64), the most characteristic feature, next to
their fauna, of all radiolarian rocks is their freedom from any, except
the finest, terrigenous material. This character is irreconcilable
with an origin in shallow waters of an open sea. A clue, however,
to conditions of semi-isolated though shallow deposition is afforded
by the calcite-mudstones of the Modiola phases previously described.
These rocks, though differing from them in composition, resemble
radiolarian cherts in being, essentially, exceedingly fine-grained.‘
Further, some contain an abundance of unicellular plankton—
Calcisphera (?). We may, therefore, find parallels for the peculiar
features of radiolarian cherts among those of the calcite-mudstones
of Modiola phases. These mudstones have, undoubtedly, been
deposited in shallow waters, but the chief feature wherein they
resemble radioiarian cherts, namely their fine grain, is anomalous
in shallow-water deposits; as we have seen on pp. d17-18,
it is necessary to suppose that the waters were under lagoon-
conditions. Similarly, it is concluded that those radio-
larian rocks that appear, from independent evidence,
to have been formed in shallow waters, owe their

1 «The Country around Ammanford’ Mem. Geol. Surv. 1907, pp. 72-76.

2 Q.J.G.8. vol. li (1895) p. 662.

3 Jhid, vol. lv (1899) p. 36.

4 The terrigenous material in the mudstones is as fine-grained as the

calcareous.

. i

Vol. 67.| THE CARBONIFEROUS SUCCESSION IN GOWER. 521

anomalous characters to deposition under lagoon-
conditions.’

In the application of this general principle to particular cases,
before a rock-group that satisfies the conditions of exceedingly fine
texture and shallow-water origin is regarded as a lagoon-phase, its
geographical extent should, if” possible, be determined, and for the
following reason. For the maintenance of lagoon- conditions it
appears to be necessary that the shallow area be of wide extent (see
‘Conditions of Deposition of the Modiola Phases,’ pp. 517-18) ; and
certainly their size has been a feature of the areas of deposition of
those lagoon-phases that are known.

The Gower radiolarian cherts a lagoon-phase.—In

the case of the radiolarian-chert group of Gower and Carmarthen-

shire, a shallow-water origin is inferred from the stratigraphical
evidence cited above, and accords with the presence, in interbedded
shales, of lamellibranchs (p. 551) known elsewhere only from
shallow-water formations. Also, the group has a wide geographic
extent: it crops out in Carmarthenshire at a considerable distance
from Gower, in a direction at right angles to the trend of the Avonian
coast ; and is known through much of South Pembrokeshire, in a
direction from Gower parallel to that coast. Consequently, we
conclude that it constitutes a lagoon-phase, and, in essentials, differs

from Modiola phases merely in consisting of the remains of siliceous
instead of calcareous organisms, in addition to fine-grained sediment.

For contrast it will, occasionally, be convenient to speak of it as
a ‘radiolarian phase.’

Although this conclusion rests primarily on the evidence cited
above, it is confirmed by other features of the radiolarian cherts on
this horizon. ‘The first is the fine, sharply-defined lamination
which is conspicuous in these, as in other, radiolarian cherts aud 1m-
parts to them astriped appearance. The lamine differ considerably
one from the other: for instance, in the proportion and nature of
their detrital material. Further, many of the lamine in the Gower
cherts are strongly lenticular, that is, wedge-bedded. The sharply-
varying composition and the impersistence of the lamine point to
the constant play of gentle currents laden with various, but always
fine, sediments. These features, therefore, are to be expected in
deposits formed under the lagoon-conditions previously described,
and, as a fact, are found in many, including the finest, rock-types
of Modiola phases, but they do not accord with a deep-sea origin—
the only logical alternative to an origin in lagoon-areas in the case
of most radiolarian cherts.

1 Radiolaria are found at the present day at all depths, in greatest abundance
in the plankton. Though they swarm in open seas, the environment in some
lagoon-areas, also, would be favourable to their increase if the salinity were
not appreciably higher than that of average sea-water,—a condition which
would be realized in the proximity of a river (p. 525). Their accumulation
in lagoon-areas would be further promoted by their ease of transport from the
open sea outside.

522 THE CARBONIFEROUS SUCCESSION IN GowER. [ Nov. 1911.

In one respect, however, the radiolarian cherts differ from all the
Modiola phases of Gower,—they are devoid of included fragments
of contemporaneous sediments.

On the other hand, further confirmatory evidence is yielded by
the black Pendleside or Posidonomya Limestones of the Midlands
and elsewhere. ‘These rocks include the horizon of the Gower
cherts and appear, from their peculiar characters, to have been
deposited in lagoon-areas'; their occurrence over a wide extent
of country testifies to a wide prevalence of lagoon-conditions on
that horizon. Some of them contain an abundance of bodies which,
Mr. Howe suggests with much hesitation, may be radiolaria (op. cit.
p. 400); and in North Devon similar limestones, there known as the
‘Venn Limestones,’ are associated with radiolarian cherts which,
as we shall presently see, probably include the horizon of the
radiolarian cherts of Gower.

The Culm radiolarian cherts also a lagoon-phase.—
We may now tabulate (Table IV, p. 523) the features of the radio-
larian phase, including some which have been observed in the Devon
radiolarian cherts, for comparison with those of the Gower Modiola
phases. The radiolarian nature of the Lower Culm cherts (the
Codden-Hill Beds) of Devon was long ago pointed out by Dr. Hinde
& Mr. Fox,? who, however, for the reasons mentioned above,
regarded them as deep-sea deposits, the associated Venn Lime-
stones being considered as but somewhat shallower in origin.’
Dr. Wheelton Hind has more recently shown* that these lhme-
stones, together with part, at least, of the cherts, are correlative
with the Pendleside Series. The correlation of the radiolarian cherts
and overlying beds of Gower with the same Series tends to confirm
the view, suggested by De la Beche and strengthened by recent
work of the Geological Survey,’ that the radiolarian cherts of the
two areas occur at one horizon.’ (It is probable, of course, that
the Devon cherts, which are much thicker than those of Gower,
include other horizons also.) The close similarity * of the cherts of
Devon and Gower is such strong presumptive evidence of community
of origin, that it is difficult to believe that those of the one area
have been formed in comparatively deep water and those of the other
in shallows. And my own observations (see Table IV, p. 523) in

1 With this view Mr. J. A. Howe, who first adequately described the rocks,
Q. J. G. S. vol. lvii (1901) p. 899, tells me that he agrees.

Qn d.Gas. vol li (1s95)ip. 609,

8 Of the shallow-water origin of the Venn Limestones there can, however,
be no doubt.

4 Geol. Mag. dec. 5, vol. i (1904) p. 392.

5 See A. Strahan, Swansea Memoir, pp. 22-25.

6 It may be useful here to mention that the horizon in Gower with which
the Codden-Hill Beds are homotaxial is that of the radiolarian cherts,
not of the underlying beds with trilobites and brachiopods referred to by
Dr. Wheelton Hind (Geol. Mag. 1904, p. 402); the latter belong to D,_5.

7 The similarity has been remarked by others, including Dr. G. J. Hinde
(Swansea Memoir, p. 25), and extends to the fine lamination and minute wedge-
bedding that I have adduced as evidence against a deep-sea origin for the

Gower cherts.

Taste [V.—TuHe Rapionarian PHASE AT THE Base oF P.

The sole macroscopic organisms of some interbedded shales
are the lamellibranchs (unbroken) mentioned on p. 551,}
known elsewhere only from shallow-water formations
(Gower).

(1) Faunal.!

Occurrence as a thin group conformably intercalated}
between two shallow-water formations,—the Rotten-},
stone Beds and the Millstone Grit (Carmarthenshire *).}

Presence of intercalated beds of ‘culm’ (coal), several}

(2) Stratigraphical

sea deposits or directly sug-
estive of an origin in shallow

| and inches thick (Barnstaple 2).

i Lenticular, wedge-bedding of many laminz, the latter)

er Latah sharply defined and differing considerably in composi-}
bo = eee tion one from the other.

Characters unusual in deep-

Characters distinguishing the phase} Fine grain of the terrigenous material.
from ordinary shallow-water
marine formations. Abundance of radiolaria.

Very rare, if existent: for, although some beds resemble

Ordinary sediments included | ordinary shales and silts and, in Devon, some contain

within the phase. corals, etc.,? radiolaria appear to be abundant through-
out and no coarse sediment is known.

Relations to the beds :—(1) below| Conformably resting upon the Rottenstone Beds in Car-
marthenshire.*
Not known with certainty in Gower, Pembrokeshire, or
North-Western Devon.?

| (2) above Sharp, but conformable, change to the Millstone Grit in
Carmarthenshire.*

| Not known with certainty in Gower, where the group!
| gives place to shales, apparently without recurrences of}
| radiolarian cherts.

| Not known with certainty in North-Western Deyon.

|

|

|

|

Development in (1) Bristol area ...| Absent.
(2) Gower w..:.-:.: Present throughout (and to the north in Carmarthenshire).
(3) outcrops south) Present throughout, except in the southernmost (Boshes-
of the Pem-| ton) outcrop.

brokeshire
coalfield.
(4) North - West-| Present throughout ®; thickness, and probably duration
ern Devon. also, much greater than in South Wales.

Note.—Features of general occurrence are not followed by the name of a locality.

1 The fauna of the Devon development, as recorded by various authors, contains no forms:
which need be supposed to have lived at great depths. For lists see G. J. Hinde & H. Fox,
op. cit.,—allorders ; H. Woodward, Geol. Mag. 1902, p. 481,— trilobites; Wheelton Hind, Geol.
Mag. 1904, p. 398,—all orders ; A. Vaughan, Geol. Mag. 1904, p. 531,—brachiopods and corals..

2 First brought to my notice by Mr. J. G. Hamling.

3G. J. Hinde & H. Fox, Q. J. G.S. vol. li (1895) pp. 617, 643 et seqq.

4 T. C. Cantrill in ‘The Country around Ammanford’ Mem. Geol. Surv. 1907, p. 75; and
in conversation.

5 The Devonian and Lower Culm of Fremington Pill, Barnstaple, said by De la Beche to
pass one into the other (‘Rep Geol. Cornwall, Devon, & West Somerset’ Mem. Geol.
Surv. 1839, p. 103), appear at present to be confined to isolated exposures affording no
evidence on the question.

6 G. J. Hinde & H. Fox, op. supra cit.

Q. J. G.S. No. 268. et

524 MR. FE. E, L. DIXON AND DR. A. VAUGHAN ON [ Nov. 1911,

the Barnstaple district of North Devon,’ so far as they go, suggest
that the cherts cropping out there are lagoon-deposits rather than
those of a fairly deep sea. Consequently, as we need consider only
these two alternatives, it is concluded that the Carboniferous radio-
larian cherts of Devon, which continue through a wide extent of the
West Country, constitute a lagoon-phase. This conclusion is not
impugned by any of the known features of these rocks in the rest of
their outcrops. Various particulars are given in the comprehensive
work of Hinde & Fox, and those that bear on the question are
mentioned in Table IV (p. 523). There is, however, much to be
learnt concerning this highly interesting group, and it is well that a
detailed examination of the Lower Culm and Upper Devonian has
been undertaken by my colleague, Mr. H. Dewey.

(4) Meaning of the Difference between the Modiola Phases
and the Radiolarian Phase of Gower.

Although the radiolarian phase of Gower appears to have been
deposited under the same conditions of depth as the Modiola phases,
in facies it presents a great contrast. Hach phase, however, reflects
the character of the fauna of the sea adjacent to the lagoon-area
in which it was formed, as the terrigenous material is, typically,
similar in all; the difference resolves itself, therefore, into one
between the facies of the contiguous open-sea fauna.

The open sea during the Modiola phases was rich in forms
possessing calcareous skeletons and giving rise by detrition to much
calcareous mud; some of this, doubtless, passed into the lagoon-
areas with fine terrigenous material, to form, with the detritus of
the indigenous fauna and, possibly, calcareous material chemically
precipitated, the characteristic mudstones. But the radiolarian rocks
were formed at a time (the commencement of P) when, in the South-
Western Province, the sea underwent a great and persistent change
in character. Calcareous organisms disappeared almost completely
from that province, being chiefly represented throughout P and higher
parts of the Carboniferous by thin-shelled goniatites and lamelli-
branchs, Siliceous forms, however, assumed greater relative im-
portance, both in the ground-living fauna,—sponge-spicules being
noticeable in the radiolarian cherts and at some higher horizons
themselves forming cherts,—and among the free-swimming groups,
where radiolaria became conspicuous.

But, although it is evident that in our area the sea from the
commencement of P onwards was inimical to so rich a calcareous
fauna as it had, up to that time, supported, yet not to a siliceous
one, we do not know what precisely was the change in its character ;
for apparently that effect on its fauna might result from any one
of several changes, such as a diminution in its soluble calcium-

1 I take this opportunity of thanking Mr. J. G. Hamling, F.G.S., most
heartily for placing his extensive knowledge of this district at my disposal.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 525

content, or a reduction of temperature.’ Neither its muddiness
nor its probable shallowness would account for the faunal change,
as similar influences had previously had no such effect, even
when acting in conjunction, as during Km. But, whatever may
have been the nature of the change in the sea, its radical
character and the wide extent of the area affected point to an
important change in the physiography of the region. [urther, there
is reason to believe that the change in the sea accompanied a
marked increase in the influence of the waters from a neighbouring
river (p. 539). And that radiolaria may abound in an area under
such influence appears to be shown by their occurrence in quantity
in the Lower Culm of Eastern Thuringia and the Vogtland, which
is regarded, from the abundance of land-plants that it contains and
for other reasons, as having been deposited in a muddy sea near the
mouths of rivers.” rn

(5) Topographical Position of Lagoon-Areas.

That the areas of deposition of the Modiola phases of Gower
were situated, probably in each case, immediately between the coast
of the Avonian sea, which lay to the north throughout the South-
Western Province, and the open water may be inferred from the
following details, partly outlined in Table V, 2, p.526. In arriving
at this conclusion, true overlap of a phase by conformable higher
beds is accepted as evidence that the lagoon-area in which that
phase has been deposited has been limited by a shore-line along
the line of overlap; while lateral replacement by ordinary marine
sediments is accepted as evidence of the deeper-water limit of the
area. For this reason a lagoon-area has been defined (p. 512) as
essentially coastal.

The lagoon-phase at the base of K in Pembrokeshire
overlaps the conformable Upper Old Red Sandstone in a northerly
direction, and is itself in turn overlapped by conformable higher
beds, which then rest directly upon Lower Old Red Sandstone or
upon still older rocks. The deeper-water limit, also, of the lagoon-
area appears to be reached in that county: for, at Freshwater West
in the southernmost outcrop, the Upper Old Red Sandstone is
followed immediately by ordinary marine sediments in which no
lagoon-deposits have yet been found.

The lagoon-phase at the base of C,+8, in Pembrokeshire
succeeds the Caninia Oolite conformably south of West William-
ston, but at that place an unconformity develops at its base.
The proximity of the lagoon-area to a shore-line, thus suggested,
appears to have persisted throughout the phase, for at Pendine

1
2

L. W. Collet, ‘Les Dépéts marins’ Paris, 1908, pp. 10-22 & 219.
J. Lehder, Neues Jahrb. Beilage-Band xxii (1906) pp. 79-80, 111,
202

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Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 527

(Carmarthenshire),* on the other (the
northern) side of the coal-basin, the
whole of C,+8, has been over-
lapped by §.,,.
Though the above statement suf-
fices for the purpose of this section,
it is advisable here to consider a
little further the interrelations of the
developments at West Williamston
and at Pendine. At the latter place
limestones, apparently no younger
than Z, are followed in order by
(1) a limestone-conglomerate; (2) a
few feet of lagoon-deposits—barren,
black calcite-mudstones ; and (3) good
representatives of 8, and D, com-
mencing with the base of 8,. There
is evidence, in the composition of
the conglomerate and in ‘ contem-
poraneous piping’ of the limestones
below, that the latter are separated
from the conglomerate by a true un-
conformity: that is, that they were :
\ raised above sea-level and eroded +
\ subaérially prior to the deposition of
\ the conglomerate. Here the uncon-
: formity is marked also by a con-

\ siderable hiatus in the sequence; on

\ the other hand, at West Williamston,

\ the only place on the south side of
\ the coal-basin where an unconformity
\ in the sequence is evidenced, the

\ break is slight and lies between C,
and C,, in other words, on a hori-
\ zon in the middle of the hiatus at
\ Pendine. Nevertheless, a considera-
\ tion * of the general development of .
\ the Avonian in the South-Western :
\ Province leads to the conclusion that
, the unconformities at both places

Pendine

Diagram,showing probable
Relations between the Unconformities

at West Williamston and Pendine (not to scale).

<
—-
_
a
_

fee ——=—
_—s
- —_——
—_——
_

The feather-edges of successively overlapping stages of the lagoon-
phase above the unconformity are indicated by short unbroken lines.

—
—_
_—
—_——

Sea-level at the commencement of So

_—"
-

; PORMILY 4
_ ae
_

1 NCON
—_—
-_

PLANE OF UN
-_

—
_
_
-
—o
—

—_—_—-

g {have been caused by one series of
ae ees earth-movements. The magnitude
== = of the hiatus at Pendine, and the
5 ese egne ae fact that the horizon of the uplift in
Se evidence at West Williamston lies .
ss within this hiatus, are explicable |

1 «The Country around Carmarthen’ Mem. Geol. Surv. 1909, pp. 81-82.
2 «The Country around Haverfordwest,’ Mem. Geol. Surv. (in the press).

028 MR. E, E. L, DIXON AND DR. A. VAUGHAN ON [Nov. 1911,

on the supposition that beds below the plane of unconformity are
overstepped between the latter place and Pendine and that beds
above that plane are overlapped in the same direction (see fig. 7,
p. 527). Both of these phenomena are to be expected, though the
extent of the overlap above the unconformity is surprising. Further,
the presence of lagoon-deposits at the base of the overlapping series
at Pendine and some other places along the same outcrop, as well
as at West Williamston, suggests that across the unexposed ground
between the latter place and Pendine the unconformity is succeeded,
as a rule, by lagoon-deposits. This is also indicated diagram-
matically in fig. 7.

The deeper-water limit of all horizons of the phase is reached in
the south: for they are represented by ordinary limestones in the
Mendips, South-Western Gower, and Southern Pembrokeshire.

The lagoon-phase at the top of 8, has not been followed
out in detail northwards; neither has its complete seaward limit
been reached, although in Gower and Pembrokeshire it is poorly
developed in the southernmost outcrops, its phasal deposits being
there largely replaced by ordinary limestones.

(6) Earth-Movements accompanying Lagoon-Conditions.

The deposition of a lagoon-phase involves the fulfilment of certain
conditions. Some of these are enumerated in paragraph 1 (below).
Again, certain conclusions may be drawn from the development
in the South-Western Province of the Modiola phases present in
Gower: as the latter are few, these conclusions are provisional ;
but as, at the same time, the evidence is consistent, it may be
useful to note its trend. It will also be seen that the deposition
of the Gower radiolarian phase appears to have followed an earth-
movement similar to one which preceded the deposition of the
Modiola phase at the base of C,.

1. The accumulation of extremely shallow-water deposits to any
considerable thickness can have been conditioned only by a general
depression of the sea-bottom relative to sea-level—positive move-
ment—over the area of deposition. Further, the depression has
been isostatic,—the term ‘isostatic’ being used simply in a descrip-
tive sense, to denote the state of an area over which the rate of
sedimentation is equal to the rate of depression. Lagoon-phases
are, by definition, extremely shallow-water deposits; the accu-
mulation of each has, therefore, been accompanied by isostatic
depression, provided its thickness is greater than the range of depth
of the water in which it has been deposited.

2. The internal constitution of the Gower Modiola phases (see
Table III, 4, p. 514) suggests (i) that in some cases (Km and the
top of §,) isostasy has been interrupted; but that in the other
(the base of C,+-S,) it has been accurately maintained, practically
throughout the duration of the phase.

3. A consideration of the nature of the beds below and above and

Fol.:67-| THE CARBONIFEROUS SUCCESSION IN GOWER. 529

of their relations to the phases (see Table V, 1, p. 526, and ‘ Varia-
tions in Depth, ete.’ pp. 532 et segqg.) leads to the further con-
clusions :—(ii) The periods of isostasy recorded in the phases have
followed either a movement of elevation (in the case of the phase at
the base of C,+8,); a continental period, during which depression
has not been exactly counterbalanced by sedimentation (in the
case of Km); or a shallowing, marine period (in the case of the
phase at the top of S,). (aii) Each period of isostasy has been ended
by a sudden movement of depression.

4. Taking into account, also, the fact that the lagoon-areas have
been coastal features, we may generalize the two last conclusions
(par. 3) thus,—lagoon-areas have been developed during periods of
steady depression, more or less prolonged, which have either
marked the first stage of the submergence of a foundering coast, or
followed intervals of upward movement interrupting a general
downward movement of a sea-floor. (The one condition is pro-
bably a particular case of the other.) These periods of steady
depression have preceded more rapid subsidences.

It follows, as a corollary, that lagoon-phases may be expected to
accompany transgressions, as do Km and the phase at the base
of C,+8,, but also that they will be subject to overlap by the
deeper-water deposits that have succeeded them.

5. The phase at the base of C,+S,, of which our knowledge is
most complete, persisted far longer in the northern than in the
southern part of the Bristol area; for in the north it is succeeded
by S, beds, whereas at Weston it is confined to the base of C,.
The significance of this fact lies in the greater proximity of the
former region to the Avonian coast. In the western area (Pem-
brokeshire and Pendine) also, the phase apparently persisted longer
near the Avonian land than elsewhere (fig. 7, p. 527), although there
the matter is complicated by overlap of higher horizons over lower.
It appears, therefore, that the depression that closed the phase
affected the seaward margin of the lagoon-area before the more
landward parts. The depression was greatest in the south, both
in the Bristol area and in the west.

No such landward lag is known in the case of the depression that
ended the lagoon-phase at the top of §.,.

The radiolarian phase.—The conclusions regarding earth-
movements, detailed above, afford a means of testing the hypothesis
that the radiolarian cherts at the base of P are similar in origin
to the Modiola phases on which those conclusions are based.

The formation of the cherts was preceded in Gower by a shallow-
marine period (D, to D,.). The following evidence suggests
that this period was closed by elevation. At Ifton,* near Newport
(Mon.), on the east, as well as at Haverfordwest? on the west,
Millstone Grit, similar lithologically to the band that succeeds the

1 Rep. Brit. Assoc. (Winnipeg) 1909, p. 478.
2 QO. T. Jones, ‘Summary of Progress for 1906’ Mem. Geol. Surv. 1907,
p. 53.

930 MR. E. E, L, DIXON AND DR. A. VAUGHAN ON’ [Noy. IgII,

radiolarian cherts in Carmarthenshire immediately and conform-
ably, rests unconformably upon §8,; at Ifton cavities (channels
and swallet-like passages) penetrating the limestone to a depth
of at least 40 feet below its uneven upper surface have been
filled with an original deposit of Millstone Grit. The un-
disturbed character of the Grit in the cavities shows that, here as
at the Haverfordwest occurrence described by Prof. O. T. Jones,
the limestone was raised above sea-level and ‘piped’ by subaérial
erosion prior to the deposition of the Grit. No direct evidence as to
the exact period of the elevation is available; but the fact that the
change from D,_, to P has been marked by a considerable physio-
graphic change in the South-Western Province (p. 524) suggests
that the movement took place at the close of D.* The relationship
of the uplift to the hiatus between 8, and the Millstone Grit would
then be analogous to the relationship of the uplift at the end of C,
to the hiatus between Z and’S, at Pendine (fig. 7, p.527). Outside
the South-Western Province, evidence of emersion between D and
P has been found in places by Dr. Sibly and Mr. C. B. Wedd,
although, as a rule, there is no such break at this horizon.?

It appears, therefore, that the radiolarian cherts of the South-
Western Province have been the first deposits formed after a
movement of elevation which has left indubitable traces in that area.
Consequently, tested in this way their suggested relationship to
Modiola phases receives support.

(7) Lagoon-Phases outside the South-Western Province.

In conclusion, it may be mentioned that the conditions under
which the lagoon-phases of Gower have been deposited have been
paralleled elsewhere and at many other horizons. Where, in such
cases, the sediments have a calcareous, or a calcareous and argil-
laceous, facies, as, for example, the Burdiehouse-Limestone Group
of Scotland, the Upper Rheetic and Cotham-Marble Group,’ and the
Solenhofen Slate, their origination in shallow areas or even lagoons
has been generally recognized, despite the fine grain of some of their
most characteristic rocks. It is of interest, therefore, that several
resemble the phases of Gower, not only in this fine grain and,
frequently, in a fine lamination, but also in their relation to earth-
movements. .

As regards the radiolarian phase at the base of P, though it is

not suggested that all radiolarian deposits have had a similar

origin, it is certain that some, at least, of those which appear, from

-variovs considerations, to have been deposited in shallow water

' It is not, however, suggested that the movement resulted in unconfomity
everywhere, for in Carmarthenshire the sequence both below and above the
radiolarian cherts is unbroken; see T. C. Cantrill, ‘The Country around
Ammanford’ Mem. Geol. Surv. 1907, pp. 72-76. -

* Q. J. G. 8: vol. Ixiv (1908) pp. 63 & 81. -
=e ‘The Lower Rhetic appears to be less peculiar in its rock-types than the

pper.

‘Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. ddl

possess features linking them so closely with the Gower cherts that
they, also, may be inferred to have been formed under lagoon-
conditions. As an example may be cited the Gondwana plant-beds
with radiolaria, described by Dr. A. K. Coomaraswimy ! as having

been ‘deposited in comparatively shallow water.’ They resemble

the Gower cherts in their fine grain and very thin bedding; and,
like various lagoon-phases, they occur near the base of a trans-
gressing series, for they lie a short distance above gneiss, from
which they are separated by merely a small thickness of sand-
stone, etc.

The close connexion between the development of lagoon-areas
and certain earth-movements, discussed in the preceding section,
and their locus on coastal shelves are related, possibly, to the fact
that some Modiola phases, such as the Burdiehouse-Limestone
Group, have been accompanied by volcanic outbreaks, including
the effusion of lavas which possess a pillowy structure,’ though the
available data are insufficient to show whether such outbreaks have
been connected with Modiola phases to a greater extent than with
the contemporaneous standard deposits.

In this connexion, however, it is important to note that radio-
larian cherts in various parts of the world are frequently accom-
panied by volcanic rocks, especially lavas possessing a pillowy
structure; and, as bearing on this aspect of the subject and the
views which I have ventured to put forward, the following words
of Prof. Charles Lapworth are significant. Speaking of a hypo-
thetical area on which radiolarian cherts and associated igneous
rocks might be supposed to have been deposited, he said *:—

‘ Consider, for example, such an area as originally forming part of a slightly
submerged continental shelf, or coastal platform, with volcanic and archi-
pelagic conditions, and overlooking...... a broad and deeper sea. Suppose,
further, the platform itself floored by rocks already metamorphosed, and that
this platform remains covered by shallow waters for an extended period of
geological time, while the sea-floor in front of it is continually deepening.
Under these conditions, only such mechanical, volcanic, or organic material
could become accumulated as rock-layers on the submerged platform, as by
their original nature or rapid cementation were incapable of being swept off
by the waves and currents of the shallow waters into the open and deepening
sea beyond. Such rock-formations as would be accumulated on the platform
would necessarily be thin, but would be lithologically varied and peculiar,’

This graphic passage, with certain modifications, embodies the
general conclusions to which I have come as to the situation in
which lagoon-phases, so ‘varied and peculiar’ in their features, have
been deposited. The chief difference hes in my interpretation of
some of those features; they point to the dominance of compara-
tively still water within the shallow area.

1 Geol. Mag. 1902, p. 305; see especially p. 506.

2 Sir Archibald Geikie, ‘Central & West Fife & Kinross’ Mem. Geol. Surv.
1900, p. 54.

3 Q. J. G.S. vol. lviii (1902) p. 440.

532 MR. E. E, L, DIXON AND DR. A. VAUGHAN ON’ _[ Nov. 1911,

V. INTERPRETATION oF THE LirHotoeicaL Sequence [E. KE. L. D.1].

(1) Preliminary Remarks.

Apart from many minor variations in rock-type, a general
sequence cf facies (Table II, p. 505) is presented by the Avonian
of Gower. In the following interpretation of this sequence it has
been assumed that those true, oolites—that is, rocks consisting
chiefly of typical, concentric and radially-crystalline ooliths, that
are widespread have been deposited in shallow water. The
assumption is justified by the current-bedding of such rocks and
the frequency of fragments of contemporaneously-formed oolite in
them, as well as by what is known both of the conditions deter-
mining the formation of ooliths* and of the situations in which
ooliths are found at the present day. ‘The oolites include some of
the purest of the Avonian limestones, but the fact that limestones
practically free from terrigenous material may be formed in shallow,
coastal waters is so well known as to need no emphasis.

The differences between the three districts (see Table I, facing
p- 505) will be discussed later.

(2) Variations in Depth and other Conditions of Deposition
over Gower as a whole at Successive Times ;
Conclusions ; Earth-Movements.

The variation of depth in time is represented diagrammatically
by fig. 8 (p. 533). In this there is no true vertical scale; the depth-
line indicates merely periods of extreme shallowness, and, by the
direction of its slope, shallowing or deepening. For horizontal
scale, the duration of a subdivision is arbitrarily and only ap-
proximately made proportional to its thickness.

In the following discussion, on which the figure is based, separate
reference will not be made to the depth of the Modiola phases; in
accordance with the views already put forward, they are represented
as extremely shallow, but with some interruption in the case of
Km and, to a greater extent, in that of the top of 8, (see Table III,
4, p. 514).

(i) The change from Upper Old Red Sandstone to
Km.—tThis was a change from ‘continental’ to marine conditions :
it is represented in fig. 8 (p. 533) by the depth-line passing below
sea-level. The change was sudden, and was unaccompanied, so far
as known, by marine intercalations in the top of the Old Red or
continental recurrences in the base of Km; but, despite a little
current-action, deposition was practically continuous.

(ii) The change from Km to K,.—Sharp increase of depth.

Gil) Conditions during K.?—The sea was muddy, but sup-

1G. Linck, Neues Jahrb. Beilage-Band xvi (1903) p. 495; and L, W.
Collet, ‘ Les Dépéts marins’ Paris, 1908, pp. 282-88.

2 On the supposition that K is equivalent to the Lower Limestone Shales
(see p. 496).

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 533

"dT ur aspyil
UDIAD] OLP DET

ported a rich calcareous fauna
belonging to standard groups, |
chiefly crinoids and brachiopods ;
the remains are found in both the
shales and the subordinate lime-
stones. In Gower, as in the
South-Western Province generally,
the conditions, for some reason,
were unfavourable to the forma-
tion of chert and dolomite. The
thick limestone in the middle of
the zone, which is widespread,
consists partly of oolite, and may,
therefore, have resulted from a
temporary shallowing (fig. 8).
(iv) The change from K
to Z.—Probably in Gower, and
certainly over the western part of
the South-Western Province, this
change of fauna was accompanied
by a rapid and long-enduring a
lithological change, from a domi- |
nantly argillaceous to adominantly
calcareous facies of sedimenta-
tion: for there the junction of the

Gower.’
as the phase

posited in as

in

Dibunophyllum

aspyd-D]OIpOT,.

Seminula
2

Sea at successive times, deduced from the sequence
O

Dolomites

ee

acket against the Modiola phase at the top of S, is unclosed on the left,
ion on p. 521, the radiolarian phase at the base of P is represented as de

3 re) zones is the junction of the Lower
> DH ° - . .
Si 2 S Limestone Shales with the main
i) . .

= een BS limestone-mass of the Carboni- |
2 9 J5 lesvyd-npowory ferous Limestone Series. This |
“lh ae = id d change in f d |

216 S widespread change in fauna an
ae ers S z rock-type probably resulted from
= Ws 3 ‘© some important physiographic |
SN =
~ a seerite = event elsewhere, but apparently :
= S it was not accompanied in Gower }
‘=

by change of depth, for the Z
limestones closely resemble the
thin limestones in K. It is note- .
worthy that ‘ contemporaneous ’”
dolomitization and the formation
of chert practically came in at
the period of the change; chert
is especialiy frequent near, but

Zaphrentis

ee

|
:

In accordance with the conclus

1 For explanation, see V, § (2), pp. 532 e¢ seqq.
shallow waters as those of the Modiola phases.

Fig. 8.—Diagram showing the variation

5 yo not below, the junction.

8. 3 fe (v) Conditions during the
m it &. two sequences: (1) Z,C, and |
3 due =z, the Modiola phase at the -
og ee ete 2 baee of Ce? amd (2) ) Ceres. :
’ 8 = —A close parallel may be drawn |

34 / S= between these two sequences, es-
aX ) == pecially in South-Western Gower :
“S S% where the lithological series is
|

504 MR. E. E. L, DIXON AND DR. A. VAUGHAN ON’ [ Noy. 1911,

most varied and most typical of the South-Western Province
generally. In the following table the members of each sequence
are placed in order of superposition, and lettered like the parallel
member of the other sequence :—

(1) The sequence Z, Ci and the ©) The sequence"@ wanker

base of C2 :—
d. Modiola phase at the base of C,. | d. Modiola phase at the top of §,,.
c. Caninia Oolite. c. Sz oolites.
b. Laminosa Dolomites (dolomitized | 6. Partly dolomitized gasteropod-
crinoidal limestones); in Hast- limestones, most conspicuous
ern & North-Western Gower in 8).

with similar dolomites of Z-age.

a. Crinoidal limestones, some dolo- | a. Various limestones, some dolo-
mitized ; lower part or all of Z. mitized ; C, with part of §,.

The chief differences between the two sequences are (1) dolo-
mitization has been much less complete in S, than in the Laminosa
Dolomites ; (2) the 8, oolites, on the contrary, are much thicker
and include dolomites more frequently than the Caninia Oolite ;
(3) the S, oolites pass gradually into the overlying Modiola phase,
whereas the Canina Oolite is separated from the parallel phase by
a sharp line and, in places, contemporaneous erosion. (In fig. 8,
p. 033, the passage of the 8, oolites into the Modiola phase is
indicated by the overlapping of unclosed brackets.)

As regards interpretation, it is clear that in each sequence the
establishment of the Modiola phase (d), that is, of lagoon-conditions,
has been preceded by a considerable period during which shallowness
of the sea, though less extreme than during the phase itself, has had
a marked effect on the facies of sedimentation: this is shown by
the presence of thick dolomites (6)* and oolites (c) below each
phase. But it is uncertain what cause has led to the replacement,
in each sequence, of dolomite- by oolite-formation, for the two
sequences are sufficiently parallel to suggest that the cause has been
similar in both. Though, in view of the frequency of contempo-

_ raneously-eroded fragments in the oolites (c), we may well suppose

that the waters in which these rocks have been formed have been
shallower than during the preceding dolomitic stages (6)—just as
the latter have been shallower than the preceding stages (a),—it
seems probable that oolite-formation has depended on some condition
additional to shallowness. For, in the Avon, the incoming of §, is
marked, as at many places in the South-Western Province, by the

1 The view of Prof. E. W. Skeats, Q. J. G. 8. vol. lxi (1905) pp. 183-38,
and others, that within certain limits shallowness favours dolomitization, is
adopted; it is supported by the relations observed (see below, p. 537) between
dolomitization and the probable relative depths of the Avonian sea. Although
S, thus bears evidence of deposition in shallower waters than those of C, in
Gower, in the Avon it includes some limestones of deeper-water origin than
any in C,.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 535

appearance, for the first time in §, of thick oolites; but, at the same
time, 8, appears, from the recurrence through it of lagoon-deposits,
to have been deposited in waters even shallower at times than
those of the §, oolites.

It may be noticed that, throughout the series Z-S in Gower, the
junctions of the zones and subzones do not correspond with marked
lithological changes, except in the cases of C, with C, and (possibly
in places) of §, with §,.’

(vi) The change from the Modzola phase at the top of
S, to D,.—The rapid replacement of the Modiola phase by deposits
of open-sea, though shallow-water, facies points to rapid but not
great deepening; the ensuing deposits yield a D fauna, and consti-
tute the basal beds of the D zone. The migration of the D fauna
from the region where it had developed into our area appears to
have coincided, therefore, with a deepening. The increase of depth
was probably immaterial, however, for the preceding fauna was
ousted both over areas where standard conditions had been dominant
during S,, even to the end, as in South-Western Gower, and over
those where lagoon-conditions prevailed towards the close of that
time, as in Eastern and North-Western Gower.

(vii) Conditions duritg D, and D, or D__,.—No rock-
sequence comparable with that above the Modiola phase at the base
of C, exists in D. ‘The initial deepening of the area of deposition
appears to have been slight and brief: for, once or twice during D
thin coals and underciay have been deposited, pointing to but little
depth at those times, though not necessarily to actual terrestrial
conditions. These shallow periods are indicated by the peaks in the
depth-curve in fig. 8(p. 533). It is noticeable that, despite the
shallowness, a lagoon-phase has not been established, the coal being
intercalated among standard marine limestones.

(viii) The change from D;,orD,_, to D,_, (Upper Lime-
stone Shales).—The incoming of the D,_, fauna accompanied a
reappearance of shale-depositing waters: such waters had been
practically absent from our area since K-times. The D,_, deposits,
however, were much more calcareous than those of K; and both
chert and dolomite were formed in considerable amount.

(ix) The change from D,, to the radiolarian phase at
the base of P.—In regard to depth of deposition, this change
resulted from the substitution of comparatively shallow conditions
by what appear to have been lagoon-conditions (p. 521). In regard
to facies of deposition, it resulted from a replacement of the cal-
careous (or calcareo-argillaceous) conditions that had prevailed in
Carboniferous times hitherto by the non-calcareous conditions—
whether cherty, argillaceous or arenaceous, marine or non-marine—
that prevailed in the South-Western Province for the rest of Car-
boniferous times.

(x) Conditions during P.—Little is known with certainty

1 In South-Western Gower, where the series has been most closely examined,
the S, oolites come in a short distance above the base of §,,.

536 MR. E. E. L. DIXON AND DR, A. VAUGHAN oN’ _[ Nov. 1911,

of the poorly-exposed sequence above the radiolarian cherts; the
P-shales, which form the lower part of the Millstone Grit Shales of
the Geological Survey, pass up insensibly through the higher part
into the Coal Measures— the latter being, in part at least, a ‘conti-
nental’ deposit.

Conclusions.

(1) The time represented by the Gower succession discussed
above may be divided into four periods, namely (4) Km-C. ;
(ii) C,—S-oolites; (111) top of 8,-D,_,; and (iv) P. During these
periods the depth varied as follows :—

(i) Km-C,. Thearea at first was under lagoon-conditions (Km);
its depth increased sharply (K & Z), and later diminished, in all
probability progressively but intermittently (Z to Laminosa Dolo-
mites ; Laminosa Dolomites to Caninia Oolite), ultimately attaining
that of lagoon-conditions again by the time that the next period
was initiated.’

(ii) C,—S, oolites. The area, with the exception of the South-
Western district, at first was under lagoon-conditions (Modiola
phase); its depth increased abruptly—to an amount during the
rest of C, greater, probably, than at any other Avonian horizon,
and later diminished, again, it would appear, progressively but
intermittently (S,; 5,), to that of lagoon-conditions by the time
that the next period was initiated. The stage of oolite-formation
was greatly prolonged, and the shallowness which marked it cul-
minated in the lagoon-conditions that followed.

(ii) Top of 8,—-D,_,. The area at first was under lagoon-
conditions (Modiola phase); its depth increased rapidly, though
probably to no great amount, and later was at times very slight”
(coal and underclay i ana 219)

(iv) P. The area at first appears to have been under lagoon-
conditions (radiolarian phase), but its subsequent history during P
is uncertain. ‘The ultimate replacement of marine waters by
continental ones (Coal Measures) was probably gradual.

(2) The foregoing summary of the periods shows that during
each of the first three the area has undergone a bathymetrical cycle,
complete in the case of the first two and probably in that of the
third also; in each of the three cases initial shallowness, that of
lagoon-conditions, has been followed by rapid deepening and, later,
by shallowing, which, unlike the deepening, has been prolonged.
The shallowing has, however, been more regular in the first two
than in the third period.

Karth-Movements.
(3) Both the deepening and the shallowing have probably resulted

1 At some places in the South-Western Province, such as West Williamston,
the shallowing culminated in emersion, the lagoon-conditions being established
as the land again sank at the commencement of the next period.

«2 At some places in the South-Western Province (see pp. 529-30) this
period probably ended in emersion.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 537

from earth-movements. The shallowing may be due to accumula-
tion of material, but, for several reasons, has more probably resulted
from movements of elevation (negative movements). Thus, in two
of the cycles it appears to have been progressive and intermittent ;
and in one (if not two) it has been completed in parts of the South-
Western Province by emersion.

(4) If we knew the exact depth in feet at which each uniform
group of the series had been deposited and the time occupied in
the deposition, by adding, for each group in turn, depth to total
thickness of deposit already formed, we could construct a curve
with these totals as negative ordinates and total times as abscisse.
This curve would show the movement of the base of the Car-
boniferous throughout Avonian time. It would then be seen that
the negative movements above mentioned have been mere incidents
in a prolonged spell of depression (positive movement). Thus,
although the incoming of oolites in 8, has, doubtless, been accom-
panied by a certain amount of negative movement, their deposition
to the thickness which they attain can have been conditioned only
by a renewal, and for a long time, of depression. In this case,
where the thickness of the deposit is enormous relatively to any
possible range of depth during its formation, depression has been
approximately isostatic (in the sense in which that term is used on
p- 528).

(3) Relations between the Different Districts of Gower at
Successive Times ; Conclusions ; EKarth-Movements.

The following interpretation is placed on the differences and
resemblances between the three districts, summarized in Table I
(facing p. 505).

(i) Of K little is known, but during the deposition of Horizon 6
the facies of sedimentation was practically uniform over the whole
area.

(ii) During the interval, Z and the lower half of the Zaminosa
Dolomites, dolomitization was much more extensive in Eastern and
North-Western Gower than in South-Western Gower ; this differ-
ence accords with the view of Prof. Skeats' and others that within
certain limits shallowness favours dolomitization, for the Avonian
sea is known from other evidence to have shallowed northwards
in the South-Western Province.

(iii) The facies of sedimentation of the rest of C, was practically
uniform over the whole area, though the ratio of the two rock-types
formed, dolomite and oolite, varied.

(iv) The fact that lagoon-conditions were established at the base
of C, in Eastern and North-Western Gower but not in South-
Western Gower was doubtless due to the southward deepening of
the Avonian sea. At this period, however, part of the Eastern

1 Q. J. G. S. vol. Ixi (1905) pp. 133-38.

ng
{
i}
iI
th

Se Ere

SSE Se

038 MR. B. E. L. DIXON AND DR. A. VAUGHAN ON [ Noy. 1911,

District approximated to the conditions of South-Western Gower :
for at Longland Bay the base of C, is not a Modiola phase, but a
group of dolomites representing standard gasteropod- and other
limestones.

(v) In the character of C, and 8, Eastern Gower definitely
links itself with South-Western Gower, and dissociates itself from
North-Western Gower. In one respect, namely in an absence of
‘contemporaneous’ dolomite and chert from the last-named district,
this difference, between Eastern and South-Western Gower on the
one hand and North-Western Gower on the other, persists to the
top of D. ‘The difference is marked in the case of dolomitization,
because outside North-Western Gower many horizons have been
affected by this alteration. As a similar difference between southern
and northern outcrops is almost as noticeable in South Pembroke-
shire; and as, further, outcrops to the north of either Gower or
South Pembrokeshire are largely if not entirely devoid of ‘con-
temporaneous’ dolomitization at horizons above C,, it is evident that
a widespread influence inhibiting such dolomitization—to which
alteration the conditions of deposition at many horizons would have
been favourable—existed in the coastal waters of the Upper Avonian
sea. In Gower this influence first made itself felt in C,; its nature,
however, 1s unknown.

(v1) During the interval, S, and D,, the facies of sedimentation
in different parts of the area varied little except in dolomitization,
as mentioned above; at the top of S,, lagoon-conditions were but
occasionally established in South-Western Gower.

(vii) Though the greater part of the ‘black lias,’ D,,, of the
Eastern District doubtless corresponds to the same group of the
South-Western, some of it, Dr. Vaughan concludes (p. 552, table),
has been deposited during the formation of part of the com-
paratively pure D, limestones which underlie D,, in the latter
district. That is, ‘argillaceous limestones and shales in Eastern
Gower are the contemporaries of pure limestones in South-Western
Gower. D, is present in North-Western Gower also, and reappears
in force, as a mass of pure limestones, along the North Crop of the
coalfield at Mynydd-y-gareg near Kidwelly,' 12 miles farther north
still. The occurrence of the pure limestone facies so far north would
point to the existence of a marked embayment in the Avonian
coast hereabouts, on the supposition that D,, was deposited
in waters essentially shallower than those of D, in its pure’ de-
velopment.” It is more probable that the difference between
D,_, and D, is primarily independent of depth. For, north-east of |
Mynydd-y-gareg, along the North Crop between that piace and
Garn-bwli (Carmarthenshire), the pure limestone facies of D, gives
place laterally to dark sandy limestones with chert,° that is, to

1 «The Country around Carmarthen’ Mem. Geol. Surv. 1909, p. 79.

2 This is the view of Dr. Vaughan, Rep. Brit. Assoc. (Winnipeg) “1909, p. 190.

37. C. Cantrill, ‘The Country around Carmarthen’ Mem. Geol. Surv.
1909, pp. 76-77. He tells me that this facies continues fora great distance east
of Garn-bwll.

- ,
“
s-

"J

- &
§
Bs

-

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 539

beds that differ lithologically from the ‘black lias’ at the same
horizon in being sandy instead of argillaceous. This lateral passage
is observable practically due north of the change from pure limestone
to ‘ black lias’ in Gower. In other words, sand was being deposited

in the north contemporaneously with mud at a considerable distance

to the south; while at a short distance to the west of both places
the water was clear. Such conditions are most readily explained
on the supposition that the region lay at the western margin of
the sediment brought into the Avonian sea by a southward-flowing
river.

(viii) The deposition of ‘ black lias’ in South-Western Gower
above D., while it persisted in the Eastern District, points to an
extension of the muddy waters described in the preceding
paragraph.

(ix) This widespread and progressive incoming of argillaceous
rocks and sponge-cherts towards the end of D probably foreshadowed
the marked advent of shales and cherts, spicular or radiolarian, at
the commencement of P. The P-shales, therefore, may, also, have
derived much of their material in the area here described from a
southward-flowing river. With this view their general character
and the lateral passage * northwards of some part of them, or of
the overlying shales, into the comparatively-coarse basal Millstone
Grit of the North Crop are in full agreement.

Conclusions.
(1) In the facies of Z and the lower half of the Laminosa Dolo-

mites the Eastern District resembles the North-Western, and both
differ from South-Western Gower; but in that of the rest of C,
there is no marked difference between the districts: while, in the
development shown by C,, 8, and D,, the Eastern District links
itself with the South-Western and both differ from North-Western
Gower.

(2) These resemblances and differences are probably attributable
to the fact that the depth of the Avonian sea and the influence
of the Avonian coast differed in the several districts; for similar
differences are observable in Pembrokeshire also, in different outcrops
bearing the same relations to the probable position of the Avonian
coast as do the parallel districts of Gower.

(3) The evidence afforded by the thicknesses of the zones and
subzones in the different districts (Table I, facing p. 505) leads to
the same grouping as the evidence summarized in (1). Thus:—

Zone Z and the Laminosa Dolomites together are at least 50 per cent.
thicker in the South-Western than in the Eastern and North-Western
Districts ;

The Caninia Oolite and C,, though variable, show no marked increase
in any direction ;

Zone S$ is 50 per cent. thicker in the South-Western and Eastern than
in the North-Western District ; and

Zone D is thicker, probably in even greater ratio, in the South-Western
and Eastern than in the North-Western District.

1 A. Strahan, Swansea Memoir, p. 29.

Q.J.G.8. No. 268. QP

540 MR. E. E. L, DIXON AND DR. A. VAUGHAN ON [ Nov. rg11,

In passing, it may be remarked that the sequence, Z-D inclusive,
is thicker collectively in South-Western Gower than at any other
place in the South-Western Province where it has been measured ;
and that D is more completely developed in this district, also, than
anywhere else in the same province.

Earth-Movements.

(4) The thicknesses, when combined with the depths at which
the deposits have been formed, in the manner outlined on p. 537,
paragraph (4), would enable us to compare the magnitudes in the
different districts of each earth-movement that accompanied
deposition. In our general ignorance of exact depths, this can
be done only for the summations of the various movements
between those horizons that appear to have been deposited at a
uniform depth in all districts. Of such horizons the most useful are
the lagoon-phases, on account of their well-defined character and
the certainty that differences between different districts (as regards
average depth of deposition of any phase) are negligible, the range
of depth in a lagoon-area being small. To apply the method :—_

The first datum-horizon is Km, which is probably developed
throughout Gower. By the time that the next datum-horizon,
the base of C,," was initiated, Km had been buried more deeply in
the South-Western District than in North-Western or Eastern
Gower, by an amount equal to the difference between the thickness
of the deposits formed in the interval in the first district and that
formed in the others; this difference, on the justifiable assumption
that K was no thicker in the North-Western and Eastern districts
than in the South-Western, was at least 300 feet (see Table I,
facing p. 505). In the interval between Km and the base of C.,,
therefore, depression was greater, by at least 300 feet, in South-
Western than in North-Western or Eastern Gower.

In the same way, by the time that the next datum-horizon, the top
of S,, was reached, the base of C, had been buried at least 400 feet
deeper in the South-Western (see, however, previous footnote) and
Eastern Districts than in North-Western Gower. And, if the radio-
larian cherts at the base of P are a lagoon-phase and may, therefore,
be regarded as a datum-horizon, by the time that their deposition
was commenced the top of S, had been still more deeply buried in
South-Western and Eastern than in North-Western Gower.

(5) From the preceding conclusions it is seen that the earth-
movements that accompanied deposition were differential and that
the regions of deeper water were the more depressed.

On the assumption’ that the differential movements were wide-
spread tilts, not irregular faulting or folding, the axis about which

1 In South-Western Gower the base of C, is not a lagoon-phase, but the
fact that it is there represented by deeper-water deposits only emphasizes the
conclusion that follows.

2 That assumption is justified, in the case of the Upper Avonian movements,
by the fact that throughout those movements the Eastern and South-Western
Districts were depressed part passu.

Vol. 67.| THE CARBONIFEROUS SUCCESSION IN GOWER. 541

hinged the total movement during the first interval, Km-C,, that is,
the Lower Avonian (see § VI) movement, was approximately parallel
to the line connecting the Eastern and North-Western facies.
(This line is given with sufficient accuracy by the line of outcrop
between the Eastern and the North-Western Districts). Similarly
the axis during the two succeeding intervals, C.-top of S,, and
D,-D,_, (that is, the axis of the Upper Avonian movements), was
approximately parallel to the line connecting the Eastern and
South-Western facies. Although this line was subsequently distorted
beyond determination by pre-Triassic movements, it was evidently
not parallel with the former axis. The axis of the Upper
Avonian movements differed in direction from that
of the Lower Avonian movement.

Summary of $$ III, 1V, & V.

Ill. Pseudobreccias resemble true breccias outwardly, but their
structure has resulted from patchy recrystallization of calcite
in foraminiferal calcareous ‘ mud.’

IV. Lagoon-phases are rock-groups which have been deposited in
extremely-shallow, coastal waters; they are characterized by
an exceedingly-fine grain and peculiar faunas.

The radiolarian cherts of Gower and of the Culm of the
West of England are concluded to be lagoon-deposits.
Lagoon-phases have marked the commencement of cycles
of earth-movement.
VY. Three bathymetrical cycles can be traced in the formation of
the Carboniferous Limestone Series (Zones K—D) of Gower.
These cycles resulted largely from earth-movements, in
which depression, on the whole, by far exceeded uplift.
Depression was greater in the seaward than in the land-
ward regions; and the direction of the hinge of the Lower
Avonian movement differed from that of the Upper Avonian
movements.

It is a pleasure to recall the assistance which I have received in
various ways from my colleagues on the Geological Survey and from
other geologists. To Dr. J.J. H. Teall I am indebted for permission
to publish some observations made in the course of my official work
in Pembrokeshire. Dr. A. Strahan I have to thank for placing at
my disposal the information obtained during the geological survey of
Gower. Reference has been made on previous pages to Mr. T. C.
Cantrill, who worked with me for a time on the ground and has put
his detailed knowledge of the Carboniferous of adjacent areas at
my disposal; Prof. L. Cayeux; Mr. H. Dewey; Mr. T. C. Hall;
Mr. J. G. Hamling; Mr. J. A. Howe; Dr. W. Pollard; and
Dr. R. L. Sherlock. To all these workers my heartiest thanks
are due.

2r2

042 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON’ [ Nov. 1911,

VI. Norss on THE DELIMITATION OF THE UPPER FROM THE LOWER
AVONIAN IN THE SouTtH-WEsTERN PROVINCE.

(1) Stratigraphical Considerations | EK. H. L. D.].

The earth-movements discussed in the previous section (pp. 536—
37), and the faunal, lithological and stratigraphical changes which
are connected with them, afford a basis for a delimitation of the
divisions of the Avonian in the South-Western Province. In
applying this principle, it is advisable to include a lagoon-phase in
the base of a division rather than to associate it with the under-
lying rocks, because such phases, in general, mark the commence-
ment of cycles of earth-movement.

For these reasous the base of the Modiola phase at the base
of (C,+8,), that is, the divisional line between C, and C,, is the
appropriate horizon at which to separate, as is necessary, an Upper
from a Lower Avonian.’ Itisthe more suitable because it is sharply
defined lithologically and, in places, is emphasized by unconformity
with the underlying rocks. And this unconformity, there is reason
to believe, is the commencement of the transgression that has brought
the Upper Avonian to rest upon far older rocks in the northern part
of the South Wales area.

In those places, however, which represent the deeper parts of
the Avonian sea, not only does the unconformity disappear, but
also, as the distance from the Avonian coast increases, the Modiola
phase itself is lost, and ultimately the base of C, may become un-
traceable by lithological means, Faunal methods, however, are
available, such as is afforded by the incoming of Cyathophyllum @
Vaughan, though, as will be seen from the following note by
Dr. Vaughan, the extreme base of C, does not everywhere corre-
spond to the maximum of the change of fauna in passing from the
Lower to the Upper Avonian.

(2) The Faunal Relations of C, to the Beds below
and above [A. V. ].

Wherever, as at Burrington, etc., C, is composed of limestones of
standard type, the C, fauna is a continuation of the y facies, that
is, an extension and amplification of the Lower Avonian fauna,
and, locally, this fauna is persistent into the base of C, (as here
defined on lithological grounds).

On the other hand, the main C, fauna exhibits the earliest
establishment of genera and gentes which are especially character-
istic of Upper Avonian time. For example :—

Corals:—

The gens of Cyathophylium aff. murchisont.
The genera Campophyllum, Diphyphyllum, and Clisiophyllum.

1 The terms Upper and Lower Avonian are used provisionally, pending
a general discussion of the Avonian of this and other areas, in some of which
other terms, such as Viséan and Tournaisian, are already in use.

Vol. 67.| THE CARBONIFEROUS SUCCESSION IN GOWER. 543
Brachiopods :—

The following gentes and groups :—

Productus corrugato-hemisphericus. Productus pustulosus.

Productus punctatus. Productus sublevis.

Productus elegans. Spirifer aff. bisulcatus.

The genera Actinoconchus, Seminula, Dielasma.

Furthermore, the C, and §, faunas are linked by

Cyathophyllum 9. Chonetes cf. comoides (of great size).
Cyathophylloid Caninie. Certain large species of Bellerophon
Early Carcinophylla. and Huomphalus.

Megastomatoid Michelinie.
Productus corrugatus, mut. C. (nearly
equivalent to Productus @ of 8,).

(In fact, beyond the occurrence of Lithostrotion there is frequently
no other distinction between C, and §,.)

Dr. Gosselet in ‘L’Ardenne’ 1888, chap. xxii, includes the C2
fauna (the Productus-sublevis Beds) with the typical S fauna above
in a single ‘ assise,’ the ‘Calcaire des Ardennes.’ The transition
from the Productus-sublevis fauna into the basal Pr.-corrugatus
fauna is, in fact, exactly that which marks the passage of C, into
S: in the South-Western Province generally.

Hence it will be entirely in accordance with the faunal evidence
to draw the line of division between the Upper and the Lower Avonian
at the bottom of the main part of C,. The divide will therefore
lie within C,, as at present defined, above the lowest part of the
standard limestones, which contains a recurrent C, fauna.

VIL Baryan Lisrs (A. V.).

Note.—Here and in the Paleontological Section, repetition of
full references is avoided by the following abbreviations :—

‘ Bristol Paper’ = Q. J. G. 8. vol. xi (1905) pp. 181-805 & pls, xxii-xxix—
* Paleontological Sequence in the Carboniferous Limestone of the Bristol
Area,’ by A. Vaughan.
‘Rush Paper’= Q. J.G.S. vol. lxii (1906) pp. 275-322 & is, XXiX-XxX—
‘Qarboniferous Rocks at Rush (County Dublin), by C. A. Matley &
A. Vaughan.
‘Loughshinny Paper’ = Q. J.G.S. vol. lxiv (1908) pp. 415-72 & pls. xlix-l
—‘ Carboniferous Rocks at Loughshinny (County Dublin),’ by C. A.
Matley & A. Vaughan.
‘ Davidson’ = ‘ Monogr. Brit. Foss. Brach.’ vol. ii (1858-63), Palzeont. Soc.

Except in the case of D,_,, as explained below, no attempt was
made to draw up an exhaustive list at any level; immediately the
zonal position had been placed beyond doubt, further search was
abandoned.

544 MR. E. E. L. DIXON AND DR. A. VAUGHANON [Novy. 1911

9

LOWER AVONIAN.

CLEISTOPORA Zone (K).
South-Western District:
Km:
Only the base of K is exposed near Rhossili.

Brachiopods :—

Chonetes ef. crassistria Vaughan + (non M‘Coy).
Humetria aff, carbonaria (Dav.) Vaughan.2
Camarotechia cf. mitcheldeanensis Vaughan.

Lamellibranchs :—

Modioliform species, including Modiola ef. lata.

Gasteropods :—

A small species of Bellerophon is common.

Ostracods.

ZAPHRENTIS LONE (Z).
Ly =

Eastern District: Threecliff Bay (indicated by the
numeral 4),

South-Western District: Rhossili to Worm’s Head
(indicated by 1).

Corals :—
Small simple Zaphrentis—1 and 4 (rare).

Brachiopods :—

Productus burlingtonensis Hall, Vaughan—1 and 4.

Small Chonetes : [ Ch. cf. crassistria predominating |—1 and 4.
Leptena—4.

Orthotetid—1 and 4.

Spirifer aff. clathratus M‘Coy, Vaughan—1 and 4 (abundant)
A small Syringothyris (ef. S. typa Winchell)-—4.

feticularia cf. lineata® (Martin) (Dav.)—1 (rare).

Athyris (Cliothyris) ef. glabristria (Phill.) (Vaughan)—4 (rare).
Camarotechia mitcheldeanensis Vaughan—1.

Crinoids :—
Dichocrinus sp.—4. (Determined by Dr. F. A. Bather, F.R.S.)

1 « Bristol Paper,’ pl. xxvi, fig. 2; also Q.J.G.S8. vol. lxiii (1907) p. 458.

2 ‘ Bristol Paper,’ p. 302.

3 This species differs very considerably from Martin’s figure in the irregular
and undulatory concentric wrinkles and in the prominence of the thick
underlayer of close-set tubes from which the fringed bands composing the
outer layer are formed.

Vol. 67.| THE CARBONIFEROUS SUCCESSION IN GOWER. 545

South-Western District: Rhossili to Worm’s Head
(indicated by 1).
- (This subzone is also exposed at Threecliff Bay in the Eastern
District; the beds are, however, here dolomitized, and fossils are
indeterminable.)

Corals :—

Zaphrentis omaliusi 1} Ed. & H., Carruthers.
Zaphrentis konincki2 Bd. & H., Carruthers.
Caninia cornucopie Mich., Carruthers.

All three are common in 1.

Brachiopods :—

The usual Z, assemblage: no list was drawn up.

Horizon y¥.
South-Western District: Rhossili to Worm’s Head (denoted
by 1).

Corals: same as under Z,, together with :—

Michelinia tenuisepta Ed. & H. and de Kon., non (Phill.).
Caninia cylindrica (Scouler in M‘Coy) Vaughan.’

Brachiopods :—

Productus cf. pustulosus + Phill. (and ef. Pr. christiani de Kon.).
Semireticulate Productus.

Leptena.

Orthotetid.

Spirifer aff. clathratus M‘Coy, Vaughan.

Spirifer cinctus de Kon.’

Syringothyris cuspidata (Martin).

Syringothyris cf. laminosa (M‘Coy) (Dav. pars), Vaughan.§

1 = Z. aff. phillipsi Ed. & H., Vaughan: as described in ‘ Bristol Paper,’
p. 270.

2 = Z. aft. cornucopieé (Mich.) Ed. & H.: as identified in ‘ Bristol Paper.’

3 Caninia cylindrica, as employed in the ‘ Bristol Paper,’ covered all the
Caninias from the entrance of the genus at the top of Z, to the maximum
of ‘C. cylindrica, mut. 8,,’ in the Lower Seminula Zone. These would now
be differentiated into C. cornucopie, C. patula, and C. cylindrica with
variants of each; at the time of our work in Gower (in 1905), however, all
these forms were lumped under C, cylindrica.

4 A common form at several points of the South-Western Province and
first appearing in y: maximum at the top of C, andinC,. The umbonal region
is strongly wrinkled and pustulose, but the skirt is often almost smooth
(ef. Productus christiani, which is abundant in ©, of Belgium).

5 Spirifer cinctus Fischer isan Upper D form anda near ally of Sp. planicosta
(M‘Coy): the form cited above is referred to as Spirifer konincki Dewalque
by Belgian writers, and is an important zonal index of Z-C.

6 The form here indicated accords with Syringothyris in its general build
and area, but is more closely allied to Spiriferina in its umbonal plates. All
Carboniferous Spiriferinas have a primitive syrinx which, however, remains
undeveloped and is buried in, and filled in by. the umbonal callus. In the
species here recorded, the syrinx is quite obvious, although confined to the
apical portion of the delthyrium.

546 MR. E. E. L. DIXON AND DR. A. VAU@HAN ON [Nov. 1911,

SVRINGOTHYRIS Zone (C).

Eastern District: Threecliff Bay (4) and Longland Bay (6).
South-Western District :—Cliff west of Overton.

C,:

Composed of the laminosa dolomite and Caninia-Oolite.

Fossils are very scarce; narrow-tubed Syringopora, large-celled
Michelinia, small Zaphrentis, large Caninia, and an early Clisio-
phyllid were, however, recorded from various places in Eastern and
South-Western Gower, as well as a band of Chonetes ef. comoides
and of Bellerophon in the Caninia Oolite of Longland Bay.

C.:
Lowest part of the standard limestones.

Zaphrentis omaliusi Ed. & H., Carruthers—4 and 6.

Zaphrentis konincki Ed. & H., Carruthers—4 and 6.

Caninia cylindrica (Scouler in M‘Coy) Vaughan—abundant in 4.
Syringothyris cuspidata (Martin)—4 and 6.

Syringothyris cf. laminosa Vaughan—rare in 4 and 6.
Cyathophyllum ¢ Vaughan (small mut.!)—4 and 6.

~

UPPER AVONIAN.’

Cs:
Main part of the standard limestones.
Corals :—
Syringopora cf. geniculata Phill., Nicholson—4 and 6.
Syringopora cf. reticulata—4.
Michelima grandis® M‘Coy—4 and 6.
Zaphrentis konincki, mut. C,4—6 (nearly at the top).
Caninia cylindrica (Scouler in M‘Coy) Vaughan—4 and 6.
Cyathophyllum @ Vaughan— abundant in 4 and 6.
Diphyphylioid Lithostrotion —Overton.
Brachiopods :—

Chonetes cf. comoides (Sow.).
Rhipidomella aft. michelini—6.

Spirifer cf. trigonalis '—6,

Syringothyris cuspidata—4 and 6.
Seninula sp. ® [ef. S. ambigua (Sow.)|--6.

1 Cyathophyllum is not established until C,; the small mutation is, there-
fore, a descending mutation, that is, a previously established member of the
gens. It obeys the general law—‘ earlier and smaller.’ :

2 The reasons for starting the Upper Avonian at this level are set outin § VI.

3 = Michelinia ef. megastoma of my earlier lists.

4 Zaphrentis konincki is a Z, to y index; this mutation is, therefore, an
ascending mutation : that is, a subsequently-established member of the gens. It
is larger, and has longer intermediates, in accordance with the general rule.
[See my note in R. G. Carruthers’s paper, Geol. Mag. dee. 5, vol. v (1908) p. 70.]

5 Small, sharply-ribbed form with a strong angular fold, somew! at produced.

6 Deeply sinuate form, recorded as Seminula ambigua by Dy. T. F. Sibly,
from Weston and the Mendips. Ne

5 & 6 These forms characterize the O-S level at widely separate localities
in England ; they are, therefore, important diagnostic forms.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER 547

Gasteropods :—
Large species of Bellerophon and Euomphalus are abundant.

Cephalopods :—

A large species of an Orthocerate is common,

SEMINULA ZONE (8).
S; :
Eastern District: Threecliff Bay (4) and the cliff-section

from Longland to Mumbles.
South-Western District: Overton (denoted by 2).

Corals:—
Michelinia grandis (M‘Coy)—2.
Caninia (Cyathophylloid) bristolensis | Vaughan—2, 4 and 6.
Cyathophyllum ¢ Vaughan—2 and 6.
Lithostrotion cf. irregulare (Phill.) Ed. & H.—4, 6 (only at the base).?
Lithostrotion martini Kd. & H., and variants—2, 4, 6,
Diphyphyllid —6 (only at the base).
Heterophyllia* sp.—2.

Brachiopods :—

Productus aff. semireticulatus, mut.S, Vaughan—2, with fragments of a
large Productus.

Productus ef. elegans M‘Coy—2 (abundant).

Chonetes cf. comoides (Sow.)—(persists at Overton as long as Caninia).

Seminula ficoides Vaughan, and varieties—2, 6 (very abundant).

Gasteropods:—
Bellerophon, Euomphalus, and Loronema abundant—z2, 6.

Bryozoa :—

Fenestellids and Heterotrypa ef. tumida (Phill.) crowd the shaly
partings at Overton (2).

Trilobites :—A Phillipsid is common—2.

[The resemblance of S, at Overton to 8, of the Avon is very
striking, for the shaly partings are crowded with the same species
of bryozoa enmeshed in a network of spines broken from the
index Productus and accompanied by the same small trilobite ;
while the limestones themselves contain at both places Caninia
bristolensis in abundance. |

S, of Gower only differs from 8, of Bristol in that, in Gower,
Cyathophyllum @ persists into 8, and Seminula is established later.

1 Proc. Bristol Nat. Soc. ser. 3, vol. x (1903) p. 103 & pl. i, fig. 4; = Caninia
cylindrica, mut. 8; of ‘ Bristol Paper.’

2 This species differs from L. irregulare of the D levels in its strikingly
ramulose habit. The beds in which it occurs have a typical C-S fauna, and
were formerly considered by me to mark the top of C,; it is somewhat more
convenient to consider them asthe base of 8,. In any case, C, and S8, are
faunally continuous both in (2) and (6).

3 Diphyphylloid Lithostrotions are not uncommon in O-S, and again
are very common in Upper D, but are apparently absent from 8 proper, where
Lithostrotion reaches its maximum.

4 Collected by the late Dr. W. B. Gubbin (Bristol Nat. Soc. op. yam cit.).

548 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON _| Nov. 1911,

So:

Eastern District: Longland to Mumbles section (6);
Bishopston Valley (8).

South-Western District: Overton (2).

The Lower (cherty) part abounds in silicified clusters of a large
Lnthostrotion—L. affine (Flem.) Ed. & H. Seminula and Productus
fill recurrent bands. Gasteropods are numerous.

The Upper (oolitic) part contains a fauna characteristic of the
S, subzone throughout the South-Western Province. Bands
crowded with Gebel Lithostrotion, or Productus corrugato-
henusphericus recur again and again.

Haimarok Upper oer

Corals :—

Syringopora—6,

Alveolites—6.

Lithostrotion martini Kd. & H., and varieties.—2, 6, 8 vee abundant).
Carcinophyllum 9 Vaughan —6, 8.

Brachiopods :—

Productus hemisphericus Sow.—2, 6, 8.

Productus corrugato-hemisphericus including ‘ P. cora, mut. S§,,’
Vaughan—2, 6, 8 (very abundant).

Papilionaceous Chonetes—6, 8.

Seminula ficoides Vaughan and varieties.— 2, 6, 8 (very abundant).

Seminula cf. ambigua Sow., an 8, form—2. (Collected by the late
Dr. W. B. Gubbin ; see ‘ Bristol Paper,’ p. 235.)

Gasteropods :—Bellerophon —6.

DIBUNOPHYLLUM Zone (D).
1D .

Eastern District: Pwll-du (5); Limeslade Bay (6), and
Mumbles Head (6a); southern end of Colts Hill (Oystermouth) ;
Bishopston Valley (8).

South-Western District: Port Eynon (3).

Corals :—

Syringopora geniculata Kd. & H.—3.

Alveolites septosa (Flem.) Ed. & H.—5.

Zaphrentis ambigua Carruthers (?)—a unique specimen from (8).

Campophyllum aft. murchisont Ed. & H.—6, 6a, 8, 3.

Clisiophylioid Campophyllum—5, 3.

Cyathophyllum murchisont Ed. & H.--5, 3, 8, 6a (extremely abundant).

Lithostrotion martini Ed. & H., and vars.—5.

Lithostrotion junceum (Flem.).—6 a.

Koninckophyllid—6.

Diphyphyloid Cyathophyllum—3, 6 a.

Cyathophylloid Awlophyllum—8.

Carcinophyllum 6 Vaughan and a yariety convergent with Dzbuno-
phyllum @—5, 6 a.

Dibunophylium 6 Vaughan, and D. ¢ Vaughan—6, 64, 5, 3, 8.

Dibunophyllum att. b Vaughan-—3.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 549

Brachiopods :—

Productus hemisphericus Sow.—d, 6a, 8 (very abundant).
Productus giganteus (Mart.)—5, 3, 64, 8.
Chonetes (Daviesiella) aff. comoides (Sow) Vaughan—5, 8. (See p. 561.)
Athyris ef. eepansa (Phill.), mut. D,—6 a.
The above fauna is characteristic of D, throughout the South-
Western Province.

D;-2 °

The uppermost beds of the Pwll-du section contain Dibunophyllum
aff. 1 Vaughan and Lithostrotion portlocki (Bronn) Ed. & H. (both of
which are D, forms), in association with the normal D, assemblage.

D,:

South-Western District: Well exposed in quarries at
Port Eynon.

Fauna :—
Corals :—

A narrow Syringopora.

Michelinia tenwisepta (Phill.) (near the top).

Alveolites (2).

Zaphrentid and ‘ Calophyllid.’

Cyathophyllum murchisoni (2).

Lithostrotion trregulare ( Phill.) (abundant in the lower part).
Lithostrotion junceum (Flem.) Ed. & H.

Petalaxis portlocki Ed, & H. (common near the top).
Dibunophyllum yY Vaughan (not common).

Brachiopods :—

Latissimoid Productus (common).
Productus ef. concinnus Sow. (broad form).
Productus cf. muricatus Phill.
Productus scabriculo-costatus (abundant at the very top).
Productus striato-corrugatus.
Papilionaceous Chonetes (small form).
Leptena cf. distorta Sow.
Spirifer planicosta (M'Coy).
Martinia cf. ovalis (Phill.).
Martinia glabra (Martin).

Bryozoa:—

Fenestella sp. nov.

Note.—Although Lonsdalia has not yet been recorded with
certainty, the above fauna may be unhesitatingly regarded as
characteristic of D,.

The D,_, Phase:

Bastach “Oyster- { Top of quarry on north of Colts Hill (a).
Diserade } mouth ‘ Black-lias’ Quarry (6).

Bishopston (road-section in Rottenstones) (c).
South-Western District: Port Eynon, above D, series) (d).

Since this phase was unknown to me when writing the ‘ Bristol

550 MR. E. E. L, DIXON AND DR. A. VAUGHAN on [| Nov. 1911,

Paper,’ the fauna recorded below is, in the main, new to the
South-Western Province.. I have consequently devoted the
Paleontological Section, almost in its entirety, to descriptions
of the most interesting components of this fauna. Reference
must, therefore, be made to that section for explanations of the
fossil names which compose the following list.

Corals =—

Michelinia tenuisepta ( Phill.) (a, d).

Amplexus (7) sp. (0).

ZLaphrentis enniskillent Kd. & H. (a, 6).

Zaphrentis oystermouthensis, sp. nov. (a, 6); common.

Densiphylium cf. charlestonense Thomson (6).

Caninia aff. cornucopie, mut. D,., (a, >).

Caninia (2) sp. (a).

Cyathaxonid (cf. Cyathaxonia aff. costata M‘Coy, Vaughan: figured in
‘Rush Paper,’ pl. xxix, fig. 5) (a).

Brachiopods :—

Productus longispinus Sow., var. (0, c, a).

Productus sulcatus Sow. (a, 0, c).

Productus scabricuto-costatus (b, c).

Productus corrugatus M‘Coy (0, c).

Productus aft. hemisphericus Sow. (6).

Productus edelburgensis Phill. (@, ¢).

Productus margaritaceus Phill. (0).

Productus punctatus (Mart.) (0).

Productus elegans M‘OQoy (0, ¢).

Chonetes sp. (0, ¢).

Papilionaceous Chonetes (small form) (0).

‘ Orthotetes’ cf. crentstria (Phill ) (0, c).

Schizophoria cf. keyserlingiana (Dav.) (6); form intermediate between
Schizophoria and Rhipidomelia (6).

Spirifer bisulcatus Sow., var. oystermouthensis, nov. (a, 6, c, d); very
abundant.

Spirifer near increbescens Hall (0).

Spirifer wickensts, sp. nov. (0).

Spiriferina insculpta (Phill.) (6, ¢).

reticularia lineata (Mart.), globular variety (4, c).

Martinia glabra (Mart.) (a, 6, ¢, d).

Athyris (Cliothyris) globularis (Phill.), and a circular variety.

Camarophoria ef. crumena Dav. (non Mart.) (0).

Camarotechia? aff. pleurodon (Phill.) (0).

Bryozoa:—

A Fenestella and a Monticuliporoid seem both to be distinctive (4, c).

* A return visit, in company with Mr. W. H. Wickes, was therefore under-
taken in order to make the list as exhaustive as possible.

* The rubbing-down of this, and of several typical specimens of Rhynchonella
pleurodon Phill. from the Upper Devonian of Wetton, has shown that this
species agrees with Camarotechiu in possessing a double and camerate septum
in the brachial valve (see ‘ Bristol Paper,’ p. 302); Pugnaz has no septum in
this valve.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 551

Trilobites:

The types of Griffithides barkei H. Woodw. (c) (Geol. Mag., 1902,
p. 484) and Gr. glaber H. Woodw. (4) (‘ Mon. Brit. Carb. Tril.’ pt. ii,
Pal. Soe. 1884, p. 40).

Note on the Bishopston Fauna.

The only noticeable differences that distinguish the Bishopston
fauna from that of Oystermouth are the absence of Zaphrentids at
Bishopston and the predominance there of Spirifer trigonalis (Mart.)
over Sp. bisuleatus Sow. The large number of species common
to the two localities demonstrates approximate equivalence of
level, and also the Upper D age of both faunas.

Note on the Horizon of the D,, Beds of Gower.’
[Evidence and inference are here set out under localities. ]

(i) Bishopston :—

(1) The Rottenstones represent the top of the D,, series ;

(2) The shales immediately above the Rottenstones, and
interbedded with the radiolarian cherts, have yielded
Posidoniella levis, Solenomorpha minor, and Glyphiceras
bilingue—tfossils which Dr. Wheelton Hind identified
and considers to indicate a level ‘low down in the
Pendleside Series.’

It is also important to note that, in shales considerably above
the level of those in the Bishopston cutting, Glyphioceras spirale
(Phill.) is recorded by the Geological Survey.’

(ii) The two quarries on Colts Hill, Oystermouth.—
The Southern Quarry is in D,, and there is a continuous series of
some 120 feet of massive limestone between it and the base oi D,,
in the Northern Quarry. This limestone is very poorly fossiliferous,
although it contains a bed crowded with a latissimoid variant of
Productus hemisphericus Sow. near the base of the Northern Quarry.

Allowing a certain weight to this form and to the small thickness
of the limestone series between the quarries, it is evident that the
base of D,_, cannot be of later date than D, age.

The fauna of the base of the D,,, series in the Colts Hill Quarry
cannot be distinguished from that of the Oystermouth Quarry,
except for the presence of ‘ Cyathaxenia’ in the first-named locality.
This coral oceurs with Zaphrentis nr. oystermouthensis in the Cya-
thaxonia Beds of the Rush and Loughshinny sequence in County
Dublin, and I have already suggested (‘ Loughshinny Paper’ p. 444)
that these last-named beds are the equivalent of part of D,, of
Gower and of part of D, of the Bristol Area.

(iii) Port Eynon.—Succeeding the massive and typical D, lime-
stones at Port Eynon are thinly-bedded limestones and shales of

1 See also § II, p. 495. * Swansea Memoir, p. 25.

552 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON [Novy. 1911,

‘black lias’ rock-facies, which are poorly exposed on the foreshore.
From these beds we obtained Productus longispinus Sow., var.,
Spirifer bisulcatus Sow., var., and Martinia glabra (Mart.), var.,
identical in form with the same varieties from Oystermouth.
Hence it is clear that the D,, fauna is, in part at least, later
than that of the D, massive limestones.

It is also interesting to observe that Productus scabriculo-costatus
does not come in at Port Eynon until the very top of the D, lime-
stones, and that, in the Bristol Area on the east and at Kidwelly
and Pendine on the west, the same form is first met with above
the typical D, and immediately below the Millstone Grit.

(iv) From the shales at the ‘ paint-mine,’ near Port Eynon, we
obtained the following fossils (identified by Dr. Wheelton Hind):—

Posidonomya becheri (Bronn). Glyphioceras reticulatum (Phill.).
Posidomelia levis (Brown)? Glyphioceras bilingue (Salter).

Dr. Hind suggests that, here, we are ‘fairly low down in the
Pendleside Series.’ Since these shales are faulted against the
limestone, it is impossible to ascertain their precise position strati-
graphically ; it can, however, be safely assumed that they lie above
the ‘ black lias’ of the foreshore at Port Eynon.

This record, taken in conjunction with the fossils cited from the
shales at Bishopston, demonstrates that a Pendleside Phase occurs
above the D,_, Phase, just as it does above the Cyathaxona Beds
(D,) of County Dublin.

Table correlating the Upper Avonian of Gower, Bristol,
and Rush (County Dublin).

RusH AND LOUGHSHINNY

BRIsto. | GOWER. (Co. Dusury).
Pendleside. |
‘Millstone Grit.’ | JE
= Ds | SRS ee mal
ong Hay D oan||
Dy a D DHE a | iby (‘ Cyathaxonia’ Beds).
Bin ze
oe Tae Dies ie De (‘ Dibunophyllum’ Beds).
Drs S De = Pe
A. | DEY 6 Unknown.

The correlation of the Bristol and Gower sequences with
those of Northumberland, Yorkshire, North Wales, the Midlands,
etc., is given in the British Association Report, 1909 (Winnipeg),
on Lower Carboniferous Zones, p. 187.

Wal. 67. | THE CARBONIFEROUS SUCCESSION IN GOWER. 553

VIII. Patmonroroercat Norzs [A. V.].

(A) CORALS.
TABULATA.
Syringopora.
Syrrneopora cf, eenrcuLata Phill., Nicholson, from C, (main part).

This is the dominant Syringopora of C,, Gower, and it there
takes the place of Syringopora cf. reticulata, which is the commonest
form in C,-S, of the Bristol area.

Description.—Broad and ramulose, with strongly thickened
tubes and not numerous connectors. Very numerous, thick, septal
spines project from the wall, and almost or quite penetrate the very
thick lining of stereoplasm. (The abundance and strength of the
septal spines causes a misleading resemblance, in cross sections, to
Lithostrotion guncewm.)

Tabule deeply dependent and distant.

Comparison.—S. geniculuta Phill., Nicholson, ‘ Tabulate
Corals’ 1879, pl. x, figs. 4, 4a, & 46, agrees closely with our
species, from which it differs only in degree, namely, it has
shorter septal spines, less widely-spaced tabule, and is far les
ramulose.

Nicholson’s conception of S. geniculata Phill. differs from the
type-figure * in the scarcity of connectors, but agrees with Phillips’s
definition of the species in respect to the ramulose habit (‘radiating,
often flexuous, branching, round tubes ’—Phill. op. cit. p. 201).

On the other hand, the accepted connotation of the specific name
geniculata (compare Ed. & H. ‘ Monogr. Brit. Foss. Cor.’ Pal. Soc.
1852, pl. xlvi, figs. 2 & 2a) disagrees with Phillips’s figure in the
absence of radiation and branching.

The type of Phillips’s species being lost, there seems little hope
of obtaining a clear conception of S. geniculata from his definition
and figure.

ZAPHRENTIDS.
Zaphrentis.

ZAPHRENTIS OYSTERMOUTHENSIS, sp. noy. (Pl. XL, figs. 1 a—-1 ¢.)
Compare Zaphrentis aff. enniskilleni Ed. & H., Vaughan in ‘ Rush Paper,’
pl. xxix, fig. 2. See also ‘Loughshinny Paper’ p. 457.

Description.—Form conical and as a rule continuously cornute,
4to5cm.in length. (Fig. la illustrates the less common form,
which is only bent at the tip.)

External surface practically smooth, except for fine annular striz
and flattened ruge.

In the calyx :—Fossula on the concave side, very deep, and
occupying more than half the diameter of the coral.

1 ‘Geol. Yorkshire’ pt. 1i (1836) pl. ii, fig. 1.

554 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON [Nov. 1911,

Major septa very strongly thickened and frequently coalescent ;
minor septa only developed in the calyx.

Horizontal sections.-—In the young stage the horizontal
section of the fossula is regularly and broadly oval, and bisected by
a strong fossular septum (Pl. XL, fig. 1 0).

In the adult, where the

Fig.9.—Zaphrentis oystermouthensis, septa have ceased to in-

sp. nov.: section below the calyx, crease, the fossula is broadly

magnified 2 diameters. (Specimen open near the wall and

figured in Pl. XL, fig. 1a.) narrows to the centre, being

3 bounded by a single septum

on either side (Pl. XL,
fig. le).

In intermediate stages the
appearance of the fossula
depends on whether the sec-
tion intersects a pair of new
septa or not; if it does so,
the fossula 1s contracted in
the middle, as in Z. dela-
nouer; if it does not, the
appearance is much like that of the adult (compare Pl. XL,
figs. le & 1d).

The septal plan has the following characters (see fig. 9, above) :—

(1) A strong thickening of the counter-septum ;

(2) Great variation in length and direction of the major septa ;

(3) A strong convexity of the longer septa (in the adult) to the generative
planes (or ‘ fossular breaks.’)

From (2) and (3) results the characteristic palmate grouping of
the septa and the dependent lateral boundaries of the counter
series.

Tabule (see fig. 10, p. 555).—The tabule are broad, strongly
depressed in the middle and along the fossula, and gently everted at
the wall.

Horizon and localities.—This species is abundant in D,, of
Oystermouth Quarry. A very similar form is rare in the ‘ Cya-
thaxonia Beds’ of Rush.

Resemblances and differences.—Zaphrentis delanouei Kd.
& H. is of much smaller average dimensions, and its dominant form
is almost purely conical (only the tip being curved), whereas the
usual form of Z. oystermouthensis is continuously cornute.

In Z. delanouet the counter (anti-fossular) septa in the adult are
regularly radial, uniformly thick, and approximately of equal
length; whereas in Z. oystermouthensis they present a quadri-
pinnate grouping, and are of very unequal thickness.

Comparison with Z. enniskillenit Ed. & H.—The type-
specimen of Z. enniskillent Ed. & H., represented in Pl. XL, fig. 2,
shows how markedly Z. oystermouthensis differs in the greater
irregularity and thickening of its septa, although agreeing in the
general plan of septation and in the position of the fossula.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 555

Evolution of Z. oystermouthensis.—Among the Z, forms,
which may all be attributed to Z. delanouei Kd. & H., is one which
agrees very closely with the young stage of 7. oystermouthensis

Fig. 10.—Zaphrentis oystermouthensis, sp. nov. : contoured plan of
floor of calyx, magnified 2 diameters, and two sections on the
same scale across the calyx. (Specimen figured in Pl. XL,

pg. 0 Ga)

al
Sdn eer ae ae ee
|
a ex. Ashen) Al che gees eg
B Ey ga Ne B’
| = Se sais 4 2 —
| Maes D3
Na Slay:
, leu ciated
| Pitta NLA
} i es
wy: AUG Wie ce ;
| Jler:
al
|

depicted in tig. 1 (Pl. XL); if this form represents the ancestral
member of the gens of Z. oystermouthensis, variation has merely
increased the size and emphasized the irregularity of the septa in
direction and thickness.

Caninia.
Canint aff. connucopte Mich., mut. D,,. (PI. XL, figs. 3 a—3c.)

I have already described the characters of this mutation under the
generic title of Ampleai-Zaphrentis, in the ‘ Rush Paper’ p. 315 &
pl. xxix, fig. 7; and also in anote kindly inserted by Mr. Carruthers
in his ‘ Revision of Carb. Corals’ Geol. Mag. 1908, p. 169.

Consequently, it is only necessary here to point out the differences
between the Upper Avonian form of the South-Western Province
and the Lower Avonian species of the same region (Z,-y), an
example of which is figured in Pl. XL, fig. 4. These differences
are appreciable only in the adult, and by comparison of the
average form at the two levels.

O.1..G. 8. No. 263. 2a

506 MR. E. E. L. DIXON AND DR. A, VAUGHAN ON’ [ Nov. 1911,

The D,_, mutation :--The tabule are gently depressed and close-
set ; the fossular depression starts near the margin. Hence,
in a horizontal section, the contours of the tabule, between
the septa and in the fossular valley, are close-set and
nearly parallel.

The thin vesicular wrapping is developed early, and is
practically continuous over the whole of the cylindrical
portion.

The y species (= Caninia cornucopia Mich., emend. Carruthers)
Pl. XL, fig. 4:—The tabule are well spaced, and the
fossular depression starts near the centre. Hence, in a
horizontal section, the contours of the tabula, between the
septa and in the fossula, are few and widely spaced.

The thin vesicular wrapping is developed late and, even
in the adult, is seldom present over the Beis part of the
cylindrical portion.

Occurrence in the South-Western Province.—The y
species is doubtless common at most localities at the top of Z,
and in C,, although Burrington (Mendips) and Stackpole Quay
(Pembroke) are the only localities which have as yet been
thoroughly searched.

At the top of D, and in D,, the upper mutation is usually to be
found, and is often abundant. It is almost invariably cylindrical
for the greater part of its length, and broader than the ‘ cornu-
bovis’ variant from the Upper Tournaisian (specimens indistin-
guishable, externally, from that variant are, however, occasionally
found).

In Gower, this mutation occurs in D, of Port Eynon and
throughout D,_, of North Colts Hill Quarry and of Oystermouth
Quarry.

In the Bristol area it is a very rare fossilin D,. In the west of
the South-Western Province—Horizon e of Ragwen Point near Pen-
dine—specimens are common, and at Bullslaughter Bay, near Boshes-
ton (South Pembrokeshire), it is very abundant in D, in association
with Glyphioceras sphericum (Martin) and a small Cyathawonia.

Caninta (?) sp. (PI. XL, fig. 5.)

This coral is remarkable for the extent and slope of the tabule,
for the shortness of the septa, and the practical absence of a fossula.
The tabule are flat, and extend almost completely across the
corallum ; they slope very steeply downwards from the convex to
the concave side.

Owing to their high dip, a cross-section cuts several tabule; and
consequently the interseptal spaces, on the concave side, appear to
be vesicular.

Above a tabula the septa are very short and amplexoid without
any septal break; underneath a tabula, they are elongated on the
concave side and Shaw on the convex nde with a small fossulee gap.
Minor septa are only developed in the calyx.

Vol. 67. | THE CARBONIFEROUS SUCCESSION IN GOWER, 557

This species appears to be intermediate between Amplewxus and
Caninia—in fact an Amplewus above the tabule and a Caninia
below: a Caninia in form, an Amplexus in calyx.

The few specimens that I have seen from Oystermouth were col-
lected by Mr. Underhill from the base of D, , in North Colts Hill
Quarry.

Mr. H. F. Barke, A.L.C., has collected from y at Burrington a
similar coral having the general form, the short septa, the broad
steeply-sloping tabule, and the inconspicuous fossula of the species
under description. The earlier coral is, however, Amplexoid
throughout, and its minor septa are practically undeveloped in the
calyx.

Amplexus.
Amptexts (?) sp. (Pl. XL, figs. 6a & 6 6.)

Form cylindro-conical, the junction of the cylindrical and conical
portions being abruptly marked by an extremely strong growth-
halt and by a “change of axial direction.

The epitheca has the strong girth-ridges characteristic of
Amplevus nodulosus Phill., but there are no spines.

The septa are long, widely spaced, and about 20 in number.

In the figured section (fig. 66) the septa extend much farther
towards the centre than is the case in the small Amplexids so
common at this level in northern localities (A. nodulosus Phill., etc.),
and they again differ very remarkably in their inequality. It is,
however, to be noted that sections differently situated with regard
to the tabule exhibit a series of equal septa which fall short of the
centre, and only differ from those of A. nodulosus in their greater
length.

The tabule are strong, distant, tall arches, flattened or gently
convex above and sharply bent down near the wall.

The species is rare in D,_, of Oystermouth Quarry, where it takes
the place of A. nodulosus, which is common at the same level in
other localities.

This species differs from A. nodulosus Phill., de Kon.’ in its
septal plan (as explained above), in its few distant tabule, and in
the small number of its girth-ridges.

CLISIOPHYLLIDS.

Dibunophyllum,

DrisuNnoPHYLLUM @ Vaughan, and an early form of DisunopHyLium
Vaughan. (PI. XL, fig. 7.)

* The figured specimen is from D, of Port Eynon; it shows a
cross-section of two cylindrical Dibunophylla, side by side.

1 «Nouv. Rech. Anim. Foss. Terr. Carb, Belg.’ 1872, p. 74 & pl. vi, fig. 5.
2a2

a

508 MR. E. E. L, DIXON AND DR. A. VAUGHAN ON [ Nov. rg1flI,

I. The. right-hand specimen presents the typical characters of
Dibunophyllum 6, namely :—

A circular, ill-bounded central area, which is completely bisected by

a somewhat flexuous mesial plate ; the general structure of the area is

simply reticulate. } ’

A loosely vesicular external area, with a very ill-defined inner boundary.
Extremely short minor septa.

II. The left-hand specimen illustrates the early form of Dibuno-
phyllum W, with which it agrees in the following characters :—

The euspidate boundary of the central area.

The suggestion of Aspidophylloid characters: that is (1) the abrupt
termination of the mesial plate within the central area; (2) the fact
that the lamellz start from the boundary of the area, and fall short of
the mesial plate.

The close-set vesicles of the external area and the well-defined inner
wall.

The elongate minor septa, which usually extend completely across
the external area.

The differences are mainly of degree only, namely :—

The early form is cylindrical (convergent on Dibunophyllum @) ;
Dibunophyliwm is conical.

The sharp, cuspidate boundary of the central area and the Aspido-
phylloid characters are more strongly marked in Dibunophyllum w.

A purely vesicular peripheral area is practically absent from the D,
form.

This early form of Dibunophyllum J is not uncommon at several
localities in the South-Western Province.

CYATHAXONIDS.
‘CYATHAXONIA’ sp.

Compare ‘ Cyathaxonia’ aff. costata, figured in Rush Paper, pl. xxix, fig. 5.

Two poorly preserved specimens, from the base of D,_, in the
North Colts Hill Quarry, were collected and kindly presented to
me by Mr. Underhill; their matrix is rottenstone. Both specimens
show the calyx, and one of them shows, at its lower end, the
highly-vaulted under surface of a tabula.

Radiating from the wall are 26 septa, short, thick, and of equal
length, except that the fossula is marked by a single short cardinal
septum.

The floor of the calyx rises centrally into a tall spear-shaped
columella, which is laterally compressed and crested like a helmet ;
the lateral surfaces of the columella are roughened by the external
edges of the numerous close-set longitudinal lamelle. By rubbing
down the columella, the lamelle are seen to radiate inwards
towards the mesial plate which is the downward continuation of
the crest.

After further rubbing down, through a very short distance, the
section cuts an underlying tabula in a roughly concentric curve,
and from this curve a second setof lamelle radiate inwards towards
the mesial plate.

ilar lla a iS

—

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 559

The structure of the columella appears, therefore, to be closely
similar to that of a Clisiophyllid, and, in particular, to that of
Carcinophyllum :—the tall vaulted tabule, each buttressed by
lamelle and crested by the mesial plate, are arranged in a series
of tents one below, and within, another.

The close approximation of the descending portion of successive
tabular vaults forms a thick tubular wall enclosing the entire
central cylinder throughout the length of the coral.

Comparison:—The specimen figured in the Rush Paper, and
cited above, was derived from the Cyathawonia Beds of Bradbourne
in Derbyshire ; similar forms, less well preserved, are common at
the same level at Rush.

The structural plan is essentially similar to that of the Gower
specimens.

By rubbing down the Bradbourne specimen through a complete
tabular interval, it was demonstrated that the mesial plate is not
continuous through the tabule, but that it starts afresh above
each tabula as a crest, and extends to the under surface of the
next tabula above; the lamelle apparently exhibit the same
phenomenon. The resemblance to the central structure of Clisio-
phyllids is, therefore, extremely close.

Specific differences from the Gower form are obvious:—In the
Bradbourne specimen there is a narrow peripheral ring of vesicles
and the lamelle are much stronger and more closely set than in
the Gower specimens. In both these characters there is a still
closer approach to structures characteristic of Carcinophyllum.

(B) BRACHIOPODS.
PRODUCTIDS.
Productus.

Propucrvus sutcatus Sow. (PI. XLI, figs. la & 15.)
Sowerby, ‘ Min. Conch.’ vol. iv (1828) pl. cccxix, fig. 2.

The holotype of the species is preserved at the British Museum
(Natural History) in the Sowerby Collection ; it was obtained from
Derby. The same form is common in Yorkshire at the top of the
Carboniferous Limestone.

The specimen here figured is from D,_, of the Oystermouth
Quarry, where the species is not common.

Description:—The pedicle-valve has the following striking
characters :—

Form cylindrical and of quadrate cross-section. Umbonal region parallel
to the marginal, and therefore invisible in a ‘back view’; the two
regions are united by a high vault. Strong reticulation on the umbonal
region. Coarse, tall, marginal ribs separated by deep furrows (whence
the specific name). Cylindrical wings strongly projecting, and each
ornamented by two rows of spines, respectively along and oblique to
the hinge-line.

The holotype of Productus sulcatus Sow. has a shallow median
sinus, whereas the Oystermouth specimen is merely flattened in
the median region.

560 MR. E. E. L, DIXON AND DR. A. VAUGHAN ON =_[ Nov. 1911,

Comparison:—P*r. costatus J. de C. Sow., ‘ Min. Conch.’ vol. vi
(1829) pl. dlx, fig. 1, differs in possessing the following characters :—

Form broad and flattened. Both umbonal and marginal areas are visible
in a ‘back view, and a vault is undeveloped. Coarse marginal ribs,
which are remarkably flattened. Strong development of spines on the
wing-ridges. Deep, narrow, median sinus.

Evolution:—the strength of the reticulation of the umbonal
region, the thickening of the marginal ribs, and the development of
spine-ridges are characters which commonly indicate phylogenetic
old-age. It seems probable that Pr. sulcatus is derived from some
such form as the specimen in the Sowerby Collection which is doubt-
fully identified with Pr. antiquatus Sow., ‘Min. Conch.’ vol. iv,
pl. ccexvii, fig. 5; whereas Pr. costatus has probably resulted, by
parallel development, from Pr. antiquatus Sow., loc. cit. fig. 1."

Propuctus (Mareinirera) Loneispinus Sow., var. (Pl. XLII,
figs. 2a & 2b.)

The predominant form of this species in D,_, of the Oystermouth
Quarry agrees with Productus setosus Phill.,? var. tissingtonensis
Sibly, Q. J. G. 8. vol. lxiv (1908) p. 77 & pl. i, figs. 6 a—-6 b.

The most striking character of this variant—namely, the large
central and marginal rib in the pedicle-valve—is well shown in
Dr. Sibly’s figures. Two further points are illustrated in the plate
which accompanies the present paper :—

Pl. XLI, fig. 2a—a partial cast of the interior of the brachial valve—
shows a marginal groove, representing a ridge surrounding the muscular
region; this is the essential character of the genus Marginifera of
Waagen.

Pl. XLI, fig. 2b—a pedicle-valve—shows the sharply-raised, collar-like

termination of the cylindrical wing.

(The structural exaggerations here noticed are probably no more
than indications of phylogenetic old-age, for they occur also in
other groups, as, for example, in Pr. concinnus.)

This variety is remarkably widespread in the upper part of the
Dibunophyllum Zone throughout the British Isles.

1 T cannot distinguish fig. 1 from the figure of Pr. semireticulatus (Mart.)
in ‘ Petrificata Derbiensia’ 1809, pl. xxxii, figs. 1 & 2. If, therefore, Pr. anti-
guatus Sow. is legitimately retained in addition to Pr. semireticulatus (Mart.),
it must denote such aform as that of Sowerby, pl. cecxvii, fig.5. On the other
hand, if it be considered that Sowerby, by his query, rejected Martin’s species
as insufficiently described and figured, and proposed the new specific name
antiquatus in its stead, fig. 1 becomes the holotype of Pr. antiquatus Sow.,
and Pr. senvreticulatus (Mart.) dies out. In my use of Pr. antiquatus Sow.
I have adopted the first-mentioned course.

2 If Productus setosus Phill. (‘Geol. Yorks.’ pt. i1, 1836, pl. viii, fig. 9) be
separated from Pr. longispinus Sow. (refigured in ‘ Davidson,’ pl. xxxv, fig. 5),
the Oystermouth form must be regarded as a variant of the small globose type
of Sowerby’s species, rather than of Phillips’s large and sulcate type. On the
other hand, Pr. se¢osws Phill., var. Phill. (op. cit. pl. viii, fig. 17) agrees closely
in convexity and ribbing with our variant.

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 561

Chonetes.

CHoneres sp. (Pl. XLI, figs. 3a & 36.)

_ Circumference rectangular, with nearly square cardinal angles.
Ribbing fine and close-set.

In the pedicle-valve the form is flattened-convex, with the
maximum rise at half-way across the valve. The strong growth-
halt and the thickened marginal band below it cause a deep
marginal depression in the cast. A shallow marginal median sinus
and a corresponding median inflection of the circumference are
occasionally developed.

This species is very common at certain levels in D,_, of
Oystermouth and Bishopston in Gower. It also occurs abundantly
farther west in the South-Western Province, at Ragwen Point
near Pendine, at approximately the same level (namely, Horizon e).

Daviesiella.

The essential character of Daviesiella Waagen as exhibited in
the genotype D. llangollensis (Day.) 1s the presence of an adaitional
pair of adductors in the large valve (‘ Davidson’ pl. lv, fig. 9—
sears lettered C).

The large Productoid Chonetes from C—Chonetes ef. comoides—
has no additional adductors; whereas, in the Productoid Chonetes
from D—Chonetes (Daviesiella) aff. comoides—these scars are very
conspicuous.

STROPHOMENTDS.

‘ OrtHoretes ’ cf. crENISTRIA (Phill.). (Pl. XLI, fig. 4.)

Description.—Hinge-line less than the width of the shell;
area asymmetrical. Brachial valve strongly convex as a whole,
but flattened in the neighbourhood of the beak.

The radial ornament is strong and markedly periodic.

The concentric fine, close-set growth-lines produce a delicate
‘crenistriation’ on the ribs and a reticulation of the narrow flat
interspaces; there are a few well-marked growth-halts. Dental
plates on a simple Strophomenoid plan.

Comparison.—In area and ornament this form approaches
very closely to O. crenistria; by its marked convexity * and more
strongly periodic ribbing it is easily distinguished.

This form is not uncommon in the Oystermouth beds (D,,_,).

1 The figured specimen is from thin shales and is crushed flat; specimens
showing the strong convexity of the brachial valve were, however, obtained.

062 MR. B. BH. L. DIXON AND DR. A. VAUGHAN ON’ _[ Nov. 1911,

SPIRIFERIDS.
’ Spirifer.

SPIRIFER BISULCATUS Sow., var. OYSTERMOUTHENSIS, nov. (Pl. XLI,
figs. 5a & 55.)
This variant differs from Davidson’s figure’ of the type of the
species (‘ Davidson,’ pl. vi, figs. 6-9) in having :-—

(1) Broad scarped ribs and a gently convex mesial fold, but little differ-
entiated from the flanks;

(2) A flatter and more transverse form ; and

(3) The cardinal region almost smooth.

It is extremely abundant in D,_
D,_, of Bishopston.
Comparisons.—Spirifer calcaratus M‘Coy * (Pl. XLI, fig. 5 ¢)
differs in its spine-like wings, unequally developed on the two sides.
This species is common in D,_, of Pateley Bridge (Yorkshire).
Spirifer bisulcatus Sow. var., Q. J. G. 8. vol. lxiv (1908) pl. 1,
figs. 3a & 36, differs in its small size and want of bilateral
symmetry ; it is common in Lower P of Loughshinny (Co. Dublin).
Ornament.—The intersection of radial and concentric orna-
ment produces the characteristic ‘ twilling’ shown in fig. 56. This
type of ornament is common to all the forms mentioned above.

, of Oystermouth, but rare in

SPIRIFER near INCREBESCENS Hall? (BL Xai tiesi6s)

Compare Sp. increbescens in Hall & Clarke, ‘Paleont. New York,’ vol. viii,
pt. 11 (1894) pl. xxx, figs. 27-80 (specimen from Chester Limestone).
oe ae the type of Sp. bisulcatus Sow.; as refigured by Davidson (pl. vi,
Our species. only differs from Sp. increbescens in its smaller size
{27 mm. wide as against 38 mm.), and probably alsoin the smaller
degree ot differentiation of the median fold from the flanks.
The shagreen-hke ornament is also not so conspicuous as in
fig. 30 of the American species.
The differences from the type of Spirifer bisulcatus Sow. are
more numerous, namely :—

(1) The smaller size.

(2) The tall, angular median fold is composed of a narrow, central, grooved
rib and two flat broad ribs, which form the steep slopes of the fold on
either side; the valve-intersection is strongly deflected into a tall
domed arch. In Sp. biswleatus the median fold is gently and con-
tinuously convex from flank to flank, and the deflection is semicircular.

1 There is considerable doubt whether the imperfect specimen in the
Sowerby Coliection at the British Museum (Natural History) is actually the
holotype of Spirifer bisulcatus Sow.; if so, both Sowerby and Davidson have
erroneously restored the mesial fold.

2 ‘Synopsis Carb. Foss. Ireland’ 1844, pl. xxi, fig. 3; refigured in * David-
son’ pl. vii, fig. 4.

ee ee — a

——— —

Vol. 67. ] THE CARBONIFEROUS SUCCESSION IN GOWER. 563

(3) The slopes of the median fold pass gradually into the flanks, whereas,
in Sp. bisulcatus, the fold is sharply separated from the flanks by a
change in curvature and by two strongly marked furrows (to the
presence of which ! the species owes its specific name).

This species (or variant) is not uncommon in D,_, near the

top of Oystermouth Quarry. Its small, convex, pingwis-like

appearance readily distinguishes it from the. broad flattened Sp. 67-
sulcatus, var. oystermouthensis, which is the predominant form.

SPIRIFER WICKENSIS, sp. nov. (Pl. XLI, fig. 7.)
Compare the following forms figured in ‘ Davidson ’ :—
‘Sp. duplicicosta,’ var., pl. iv, fig. 4 (from Park Hill).
‘Sp. grandicostatus,’ pl. vii, figs. 8-11 (from Bolland).
Also compare :
Sp. cameratus Morton, var. figured in Hall & Clarke, ‘ Paleont. New York,’
vol. vill, pt. 11 (1894) pl. xxxil, fig. 12, from ‘ Coal- Measures.’ 2
See also Sp. striatus, var., in Q. J. G. 8. vol. lxii (1906) p. 310 (from the
Curkeen Limestone).
Description.—Cardinal angles often dissimilar, as in the
Bolland specimen cited above.
— Median fold bounded by two deep furrows.
t Ribs few, but tall, angular, and separated by deep furrows; the
striking and irregular manner in which they fork, so that the
branches often diverge very widely, makes the species easy of
recognition.
In so far as the type of ribbing is concerned, this is an old-age
character that can be arrived at by structural change within
distinct gentes. For example :—

(1) The form in the Curkeen Limestone (Co. Dublin) is clearly a derivative
from a striate stock, since it is connected with more normal members
of that stock by intermediate forms.

(2) The American variant is derived from a stock having the ribs in
fascicles, and has been evolved by the blending of each fascicle into a
single strong rib.

(3) It is probable that in very many cases this type of ribbing has been
arrived at from a variant of Sp. bisulcatus with coarse ribs, in which
the characteristic forking is already initiated near the margin.

Hence this species is rather of the nature of a circulus than of a
true species; it has, however, an important stratigraphical value,
since it is widely distributed and is as yet unknown below D,.

In the Bristol area Sp. wickensis occurs abundantly in D, at
Wick (whence the specific name) and, somewhat rarely, at Wrington
and in the Avon section at the same level.

In Gower it is a rare associate of the D,_, fauna, and has been
found in Oystermouth Quarry.

1 Davidson seems to have regarded the two grooves on the fold itself, to
which the fold owes its tripartite character, as the reason for its specific name.
Sowerby, however, states clearly that the character recorded in the name is the
separation of the fold from the flanks by two deep furrows.

+ Hall & Clarke assign to the ‘ Coal-Measures’ British specimens obtained
from Upper D (for instance, the types of the species :—Spirifer striatus, Reticu-
laria lineata, Martinia glabra, Productus longispinus).

564 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON__| Nov. 1911,

In Northumberland it has been found by Mr. Stanley Smith at
the level of the Acre Limestone (probably of D,_, age); it is there
associated with a brachiopod tauna similar to “that of Wick and
with corals of Oystermouth facies.

The form from the Curkeen Limestone of County Dublin also
occurs at approximately the same level.

Martinia.
MARTINIA GLABRA (Mart.), varietal form.
Compare VW. glabra, mut. P., ‘ Loughshinny Paper’ p. 468 & pl. ], fig. 8.

This variety differs from Martin’s type in its more equidimensional
form and in the more flattened brachial valve. The cast of a
pedicle-valve shows the absence of dental plates, and the presence
of strong ridges which indicate deep furrows in the interior of the
valve—characters which are distinctive of the genus, and are equally
well exhibited in J/. ovalis (Phill.).

Compared with the later mutation from P of Loughshinny, the
muscular scars are very indistinct, whereas they are deeply
impressed in the Loughshinny form. |

This variety occurs throughout the Oystermouth Series (D,_,);
it is rare immediately above the massive limestone of North Colts
Hill Quarry, abundant in Oystermouth Quarry, and rare again in
the Bishopston cutting.

AVEEDYER DS:

Athyris.
ATHYRIS (CLIOTHYRIS) GLOBULARIS (Phill.). (Pl. XLI, fig. 8a.)

The holotype of Phillips’s species is preserved at the British
Museum (Natural History) in the Gilbertson Collection; it bears
clear indication of the former presence of fringed expansions in
the fine imprints which they have marked upon the valve. Hence
this species may be regarded. as a dwarf and late representative of
the gens of A. glabristria, with which it agrees precisely in form
and in the strongly developed beak.

The Oystermouth specimens only differ from Phillips’s type of
A. globularis in the preservation of portions of the actual fringes.
These expansions are very close-set, and the ‘fringe’ starts
immediately at the suture-line with the valve.

Specimens are common at one level in D,_, of Oystermouth
Quarry, and the species is widely spread at the top of the lime-
stone-massif in the Midlands and South Yorkshire. ;

Comparison with Athyris (Cliothyris) roissyi (L’Eveillé),
Vaughan (figured in this paper, Pl. XLI, fig. 8b).—The Bristol species
is abundant in Km and persists into Z. It differs from A. globularis

in its non-transverse form, in the upright and small beak, the

well-spaced principal expansions, and the existence of a narrow
unfringed basal portion at the line of attachment of each expansion.

Wolk 67.] THE CARBONIFEROUS SUCCESSION IN GOWER, 565

Comparison with <Athyris roissyi (L’Eveillé).\—The figures
of L’Eveillé’s type depict a shell of more or less transverse form
with a large beak and perforation, a well-marked median fold and
strong distant growth-halts. If we accept the tacit assumption,
made by both L. G. de Koninck and T. Davidson, that the valves
were ornamented with fringed expansions (neither mentioned in
L’Eveillé’s text nor indicated in his figures), L’Eveillé’s species
can be well matched by the Z, form of ‘ Cliothyris glabristria’ in
the South-Western Province. This conclusion, if recognized,”
would involve the following changes of nomenclature :—

‘ A. glabristria, mut. Z,’ becomes A. roissyi (L’Eveillé).

‘ A. roissyi’ of Km and Z becomes a new species, on account of its difference
of form and beak (see Pl. XLI, fig. 8).

Athyris globularis stands, since it is differentiated from the
above forms by the closeness of its expansions and by the fact
that they are completely fringed.

' TX. Summary oF PALZXonrToLoGICcAL SECTIONS.

(a) The existence of a Modiola phase at the base suggests
conformity to the underlying Old Red Sandstone ; this conformity
has been demonstrated by Mr. Dixon in North-Western Gower.

(6) The zones Z, C,S and D contain faunal assemblages identical
with those of the same zones in the Bristol Area.

It is, however, interesting to note that small Zaphrentes of Lower
Avonian aspect are abundant just above the Canina Oolite, in
association with Cyathophyllum ¢ and Michelinia grandis.

(c) The faunal evidence suggests that the lower limit of the
D,_, phase lies within D, of Bristol, but that the upper limit of the
phase lies above that subzone and within the ‘ Millstone Grit’ of
the Bristol sequence.

(d) The upper part of C, is so closely related faunally with the
overlying Lower Seminula Zone, that it is impossible to refer these
two subzones to different divisions of the Carboniterous Limestone.

(¢) The most important coral and brachiopod groups discussed
in the paper are :—

Zuphrentis oystermouthensis.

Productus sulcatus and Productus costatus.

Forms included in the group of Spirifer bisulcatus.
Athyris globularis and A. roissyi.

I have received much help from the following geologists, and to
them I tender my heartiest thanks:—Mr. R. G. Carruthers,
Dr. Wheelton Hind, Dr. F. A. Bather, Mr. J. W. Tutcher, and
Mr. W. H. Wickes.

1 Mém. Soc. Géol. France, vol. ii (1835) pl. ii, figs. 18-20.

* L. G. de Koninck was quite aware of the fact that Athyris roissyi had
been wrongly identified; but he suggested that no change should be made, in
order to avoid confusion. See Ann. Mus. Roy. Hist. Nat. Belg. vol. xiv, pt. 6
(1887) pp. 85. 86.

566 MR. E. E. L. DIXON AND DR. A. VAUGHAN ON [ Nov. 1911,

EXPLANATION OF PLATES XXXVITI-XLI.

Prats XXXVIII.

Fig. 1. ‘ Pitted’ limestone in D,, Tor-gro (North-Western Gower). A steeply-
dipping, weathered bedding-plane. The bag near the right lower
corner affords a scale. The limestone is a pseudobreccia, and shows
the usual rough surface. (See pp. 490 & 499.)

_ Fig. 2. Undolomitized pseudobre: ‘cia in D,, slightly weathered, Tor-gro. The

dark angular ‘fragments ’ are well defined. Dolomite is absent, from

both ‘fragments’ and ‘ground-mass’; the amount of ar gillaceous
impurity is very slight. (See pp. 507 et seqq-)

Puate XXXIX.

Partly dolomitized psevdobreccia in D,, Port Eynon (South-Western Gower).
Microscope- -section X 8 diameters. The dense material is unaltered
‘ground-mass’; the less cloudy, much more foraminiferal areas, at the
top, bottom, and left, are the recrystallized ‘ fragments’; the rhombo-
hedral crystals, many with a diagonal eross, in the ‘gr ound-mass’ are
dolomite. (See pp. 507 et segq.)

Puate XL.

Upper Avonian corals from the Cyathaxonia Phase (D,-,) of Oystermouth,
Gower (together with certain forms for comparison).

Figs. la-le. Zaphrentis oystermouthensis, sp. nov. (p. 593). Fig. 1a, ex-
ternal and calicular view, natural size. Base of D,_,, North Colts
Hill Quarry. Collected by Mr. Underhill. (For septal plan and
curvature of tabulz in this specimen, see text-figs. pp. 554 & 595.)
Figs. 1 d-le. All from J),_,, Oystermouth Quarry (‘Black Lias’).
Fig. 16, a very young form, x 24. Fig. le, intermediate stage
of the same specimen, x 13. Fig. 1d, intermediate stage of
another specimen showing differences due to the position of the
section with regard to new septa. Fig. le, adult stage, x 14.

Fig. 2 (for comparison). Zaphrentis enniskillent Ed. & H. (p. 554). Natural
size. The holotype of the species. [ Olim Coll. Geol. Soc., RB. 5460.—
Now in the Museum of Practical Geology.| Lough Gill (Co. Sligo).

Figs.| 3a-3¢. Caninia aff. cor nucopie Mich., mut. D,_, (p. 555). Three
sections from the same spObE DET D,_, of Oystermouth Quarry.
Fig. 3a, young stage, X 2-7. Fig. 36, intermediate stage, x 14.
Fig. 3c, adult stage, x Id.

Fig.’ 4 (for comparison). Caninia cornucopie Mich., Carruthers (p. 556).
Section, X 14. Stackpole Quay, Pembroke. Horizon Ye

Fig. 5. Caninia (2) sp. (p. 556). Natural size. Base of D,_,, North Colts
Hill Quarry. Collected by ae Underbill.

Figs.6a&6b. Amplexussp. (p. 557), Dy 3 of CUSHION Quarry. Fig. 6a,
external view, X 14. Fig. 60, section, x 1-2.

Fig. 7. Dibunophylium 6 Vaughan (to right) and Dibunophyllum aff.
Vaughan (to left), slightly reduced (xX ‘94). D, of Port Eynon
(p. 598).

Puate XLI.

Upper Avonian brachiopods from the Cyathaxonia Phase (D,_,) of Oystermouth
and Bishopston, Gower (together with certain forms for comparison).

Figs. la & 10. Productus sulcatus Sow. (p. 559). Natural size. D,_, of
Oystermouth Quarry. Fig. 1a, pedicle-valve, rostral view. Fig. 14,
pedicle-valve, marginal view.

1 In figs. 36 and:3 ¢ the fossula lies to the right of the plane of symmetry
for the external surface ; figs. 3a and 4, in which the fossula lies in the plane
of symmetry, have been set obliquely so as to facilitate comparison.

Quart. Journ. Geot. Soc. Vor. LXVII, PL. XXXVIIL

Fic. 1.—‘Pittep’ LIMESTONE IN D,, ToR-GRO (NORTH-WESTERN GOWER).

¢Prer

Be ail Pinta Geol. Sure. Colla).

Fic. 2.-UNDOLOMITIZED PSEUDOBRECCIA IN Di, SLIGHTLY WEATHERED,
TOR-GRO.

4, : . =
EK:

7. C. Hall, Photo. (Geol. Surv. Colin.). Bemrose Ltd., Collo., Derby.

4

tf
%
Mi
#3
4
§

Quart. Journ. GEoL. Soc. Vor. LXVII, Pr. XXXIX.

y J = ~

EZ, EED:, Photo.

*

. PaRTLY DOLOMITIZED PsEUDOBRECCGCIA IN Di, PortT-EYNON
(SouTH- WESTERN Gower), x 8 DIAMETERS.

J

Fig. le.
Bemrose Ltd., Collo., Derby.

Quart. Journ. Geot. Soc. VoL. LXVII, PL. XL.
Fig. \d.

(* COMPARATIVE FORMS.)

Fig. Ic.

AVONIAN CORALS From Dz and Dz, GOWER.

J.W. Tutcher, Photo.

Quart. JOURN. GEOL.

Fig. 2a.

J. W. Tutcher, Photo.

AVONIAN BRACHIOPODS FROM

(* COMPARATIVE FORMS.)

Soc. Vor. LXVII, Pr. XLI-

Bemrose Ltd., Collo., Derby.

D,, GOWER.

rat,

i
Eien
oe

rH
Toney

—

THE CARBONIFEROUS SUCCESSION IN GOWER. 567

Vol. 67.]

Figs. 2a & 26. Productus longispinus Sow., var. (p. 560). D,., of Oyster-
mouth Quarry. Fig. 2, cast of interior of brachial valve, x 1°5;
Fig. 2 5, pedicle-valve (showing wing), x 1‘6.

Figs.3a@ & 36. Chonetes sp. (p. 561), natural size. Fig. 3a, cast of pedicle-
valve; D,., (top), Bishopston. Fig. 3, pedicle-valve from D,_,
of Oystermouth Quarry.

Fig. 4. ‘ Orthotetes’ cf. crenistria (Phill.) (p. 561). Brachial valve and area,

natural size. D,_, of Oystermouth Quarry. [The specimen is
crushed, and does not show the strong convexity of the valve. |

Figs. 5a & 5b. Spirifer bisulcatus, var. oystermouthensis nov. (p. 562).
Fig. 5a, pedicle-valve, natural size. D,_, of Oystermouth Quarry.
Fig. 50, portion of a brachial vaive, enlarged to show ornament.
Same locality.

Fig. 5¢ (for comparison). Spirifer calcaratus M‘Coy (p. 562), natural size ;
a pedicle-valve from D,_, of Lolley Scar Quarry, near Pateley Bridge
(Yorkshire).

Fig. 6. Spirifer nr. inerebescens Hall (p. 562), natural size ; a brachial valve
from D,-, of Oystermouth Quarry.

Fig. 7. Spirifer wickensis, sp. nov. (p. 563), natural size, a pedicle-valve from
D,., of Oystermouth Quarry.

Fig. 8a. Athyris (Cliothyris) globularis (Phill.) (p. 564), a pedicle-valve, x 1°5.
D,., of Oystermouth Quarry.

Fig. 86 (for comparison). <Athyris (Cliothyris) roissyi of the ‘ Bristol Paper.’
Beak and brachial valve, x 1:6 (p. 564). Km (‘ Modiola phase’)
of the Avon Section.

Discussion.

Dr. A. SrraHawn observed that this region was one which called
especially for combined stratigraphical and paleontological work.
The Carboniferous Limestone Series presented a succession of stages
in development. The fullest development was exhibited in the
southernmost occurrences, as regarded both the sequence and the
thickness of zones. A second stage, showing an incomplete sequence
and considerable attenuation, with indications of near-shore origin,
was presented along parts of the margin of the coalfield. Lastly,
in the northernmost occurrences, near Abergavenny and at Pen-
cerig-calch, the series dwindled away to 100 feet or less, while in
Pembrokeshire it was wholly overstepped. The inference followed
that the coast-line ran through Pembrokeshire, and not far north of
Abergavenny. ‘Traverses made at right angles to the coast-line,
and comparisons of these various stages of development, could not
fail to yield results of the greatest interest. The only other district
where such a traverse was possible, lay on the northern side of this
same Carboniferous land-area, where the Limestone Series could be
followed continuously through Denbighshire to its disappearance
in Shropshire. That the radiolarian cherts were of shallow-water
origin seemed obvious, nor, so far as he was aware, was there
evidence of deep water in any part of the Limestone Series:
sedimentation or formation of organic deposits seemed to have
kept pace with subsidence so nearly that the water was generally
shallow. But he was unable to follow the Authors in their iden-
tification of lagoon-phases. He enquired whether further evidence
had been obtained for identifying and defining the Posidonomya
Zone. The change of fauna at the base of the radiolarian cherts

568 THE CARBONIFEROUS SUCCESSION IN GoWER. [Nov. 1911,

was most pronounced, but the upward limit of a ‘ Postdonomya
Zone’ was extremely vague.

The Prestpent (Prof. Warts) congratulated the Authors on the
number of issues that they had raised, and on the discussion to
which the paper had given rise. He agreed with Dr. Strahan that
the South Wales limestone outcrops afford an unrivalled opportunity
for the study of the broad variations occurring in a formation
throughout its geographical extent: the extent and continuity of
the South Wales sequence being far more favourable than the
meagre outcrops north of the Midland barrier. He referred to
the difficulty in finding modern parallels for the lagoon conditions
postulated in the paper, which required wide extent of shallow
water, abundance of organisms, and yet freedom from clastic
material. Coral-reefs presented almost the only example of such
conditions to be observed at the present day. He deprecated too
much controversy on the application of Belgian subdivisions to
British strata, until the exact extent and character of these
subdivisions had been again checked in their couatry of origin.

Mr. R. H. Trppeman said that he was much pleased with a paper
which dealt with so many points of interest. He agreed with the
Authors that many of the limestones of Gower had been formed in
shallow waters; indeed, when mapping the ground, he thought it
probable that the oolites had been formed under eolian conditions,
Referring to the term ‘lagoon’ so much employed, he wished to
ask Mr. Dixon whether he had seen anything in the area at all
resembling a barrier-reef or reef-knolls, such as the speaker had
found in the North of England: he himself had failed to see any-
thing similar in Gower. He was satisfied with the identification
of the ‘Black Lias’ of Oystermouth with the Bishopston white
rottenstones, and mentioned that the former, when. exposed for a
short time to the weather, became covered with a white powder.
He believed that the shales above the cherts represented the
‘Bowland Shales’ (of Phillips), a name which had priority over
the Pendleside Shale of a later author.

Mr. A. L. Leacu remarked that the rocks formed under ‘ shallow-
water’ conditions appeared to be of great importance in the area
described by the Authors, but the application of the definite term
‘lagoon-phase’ to the conditions under which these sediments
were deposited seemed to need further justification. The Authors
apparently did not claim a coral-reef origin for any of the rocks
described, and the oceanic atoll-lagoons were therefore rightly
excluded, as also those coastal lagoons which were bounded seawards
by coral-reefs, since neither in Gower nor, so far as his observations
went, in Pembrokeshire, were there any limestones of coral-reef
origin. Lagoons bounded seawards by islets or by submarine banks
were, he thought, usually associated with river-mouths, and were
necessarily adjacent to land. Deposits formed in such lagoons
would show, he thought, some unconformity with the boundary-
deposits, and moreover terrigenous material would probably be
present. He had not observed any deposits in the adjacent Pem-
brokeshire area that could be assigned to lagoons of this type,

~

Vol. 67. | THE CARBONIFEROUS SUCCESSION IN GOWER. 569

The sudden change from the ‘calcite-mudstones’ of S, to the
limestones with a deep-water fauna of D,, as seen at Lydstep in
Pembrokeshire, was difficult to reconcile with the suggested lagoon-
formation of the ‘ calcite-mudstones.’

Dr. T. F. Sisty remarked that numerous interesting questions
had been raised by this paper. Obviously, a careful study of the
evidence would be necessary, in order to appreciate the Authors’
conclusions with regard to ‘ complete cycles of intermittent change,’
arrived at by comparing the sequences of lithological types in the
three districts. The speaker, however, pointed out that, in view of
the small extent of the area under consideration, and the distinctly
shallow-water facies of the Avonian as a whole in this area, cor-
relation of movements of the sea-floor in different parts of this
area with similar disturbances in different parts of the much
larger Bristol area, must be open to considerable error. He asked
Mr. Dixon for a definition of the distinctive lithological facies of a
‘Jagoon-phase.’

It would have been instructive to hear a summary of the special
features of the faunal succession in this area. The Avonian fauna
appeared to have maintained, on the whole, its normal progression,
despite remarkable vicissitudes. With regard to the very wide
question of the limiting horizon between Lower and Upper Avonian,
was this area, which clearly suffered a maximum of disturbance, a
favourable one in which to deal with the question on a faunal
basis? The description of the D,—D, phase of the Dibunophyllum
Zone would doubtless furnish many important facts, and would be
especially valuable to those interested in the difficult subject of the
correlation of the highest Avonian beds in different areas.

Mr. J. H. Cotrins regretted that the Authors had not supplied a
cross-section, and that no statements had been made as to the
thicknesses of the various zones and their subdivisions.

Mr. Cosmo Jouns welcomed this account of the lithology and
physiographic conditions of deposition of the Carboniferous Lime-
stone in a most interesting district. The Authors’ careful observa-
tions confirmed the evidence obtained in other areas, and demon-
strated the shallowness of the Lower Carboniferous Sea. The
non-appearance of dolomites at horizons where, from the evidence
of shallowing, they would be expected, might be explained if a
critical temperature rather than depth be the factor determining
their occurrence. It would appear that the Authors, by ‘ lagoon-
phase,’ simply meant partly land-locked shallow waters, free from
disturbance by currents. In such restricted areas the water might
easily be appreciably warmer than in the outer sea, and thus
dolomites for this reason might have a local development only.
This suggestion could be put to experimental proof without much
difficulty, and temperatures near 30° C. would, from such evidence
as is available, seem most promising. He regretted the absence of
Dr. Vaughan, in view of the important faunal considerations that
arose out of the work done in the area.

Mr. G. W. Youne enquired whether the Authors had formulated
any theory as to the cause of the frequent oscillation of the sea-

570 THE CARBONIFEROUS SUCCESSION IN GOWER. _[ Nov. 1911,

bottom which they believed had taken place; and also whether
their suggestion that a considerable deepening occurred at the close
of the S, lagoon-stage was compatible with the presence, in the
succeeding deposit, of a ‘thin coaly layer.’ As this, in one portion of
the district, was accompanied by an underclay, it seemed to present
a difficulty.

Mr. A. WabdE compared these beds with some which had been
forming quite recently at the northern end of the Red Sea. Here,
there was a very shallow platform fringing the Eastern Coast, and
running out to sea for upwards of 20 miles. A series of limestones
could be traced on the islands from the edge of the platform to
the mainland. The changes which took place in the physical
characters of these limestones might clear up the difficulty that
the Authors had with the limestones of the Seminula Zone,
which were dolomitic in the south-west of Gower but were not so
in the north-west. They were, however, entirely oolitic in this
direction. The limestones referred to in the Red Sea area
changed from massive limestones (not oolitic, but to some extent
dolomitic) on Jubal Island at the edge of the reef, to oolitic
lhmestones interbanded with beds of very fine sediment on Gaysum
Island, half-way between Jubal and the coast; while on the
mainland, they consisted of oolitic hmestones with many gasteropod-
remains, interbedded with sands and coarse grits—very like the
material of the Millstone Grit. The later oolites were evidently
laid down in the estuary of some river.

He was interested to hear that Mr. Tiddeman had long con-
sidered that some of the oolites of Gower might have been laid down
under eolian conditions, because some of the oolites in these
recent Red-Sea beds were probably affected by similar conditions.
It seemed, therefore, that the conditions which the Authors
considered to have existed during the deposition of these beds in
Gower, might find a close parallel in the conditions which recently
existed, and probably still exist, in the northern part of the
Red Sea.

Mr. Drxon, after thanking the Fellows for their kind reception
of the paper, remarked, with reference to an observation by the
President, on the usefulness of a classification of the Lower Car-
boniferous in facilitating comparison of developments in different
districts ; and added, in reply to Mr. Tiddeman, that the occasional
occurrence of large marine fossils in even the most unfossiliferous
oolite militated against the view that any of these rocks were of
ceolian origin.

Regarding the name to be applied to the shales above the
Limestone Series in Gower, the Pendleside Series had good claims, in
that it represented rocks to which a distinctive fauna had been
ascribed; and further, in answer to an objection raised by
Dr. Strahan, he remarked that the correlation depended not solely
on the occurrence of Posidonomya becheri Bronn, but rather on that
ot Glyphioceras spirale Phill. In agreement with Mr. Tiddeman,
he did not think that any of the Gower limestones possessed
features characteristic of true coral-reefs.

fond

Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. O71

In reply to Mr. Leach and others, he stated that the calcareous
‘lagoon-phases ’"—the Modiola phases—were all distinguished in
places by exceedingly fine-grained calcite-mudstones with an im-
poverished fauna of lamellibranchs (especially Modtola), ostracods,
and Spirorbis.. A certain amount of terrigenous material, mud
and fine sand, was found in them all.

He took exception to Dr. Sibly’s remark that the Gower area
had been exceptionally shallow ; on the contrary, he considered it
in many respects typical of the South-Western Province.

He was very glad to hear from Mr. Wade that the conditions
which must have prevailed during lagoon-phases could be approxi-
mately paralleled at the present day along the coast of the Red
Sea, as he had not had an opportunity of enquiring whether modern
representatives of them were known. ‘The suggestion of Mr. Cosmo
Johns that a lowered sea-temperature might account for the absence
of dolomite from the Upper Avonian of the North-Western district
was welcomed, as the speaker had suspected that the influence of
the waters that deposited the Pendleside Shales was beginning
to make itself felt there at that time, and a low temperature would
also explain the extermination of the previously-rich fauna from
the area on the arrival of those waters in force.

In conclusion, he remarked that, although there appeared to be
no reason why lagoon-conditions should not be established during
any shallow-water period, it was a matter of observation that they
immediately preceded sharp subsidence.

1 Lack of time prevented the speaker from illustrating the differences between
the lagoon-phase deposits and the standard limestones as being similar to those
between the Rheetic—a typical lagoon-phase—and the open-sea Lias.

Q.J.G.8. No. 268. 2B

572 PROF, J. W. GREGORY ON [Nov. 1911,

18. Conrrisutions to the Grotocy of Cyrenatca. By Prof. J. W.
Greeory and others. (Read March 8th, 1911.)

[Prates XLIJ-XLIX.]

(A) Lhe Guotocy of Cyrrenatca. By Joun Watrter Gregory,
D.Sc., F.R.S., F.G.S., Professor of Geology in the University
of Glasgow.

[Prats XLII—Map ayp Sections. |]

ConreEnTs.
Page
TPR GPOR MUCHO 9. o025.5 on sinwicin ono deeaniceenieas cage Sea eee 572
ID, Hield=Observations 2. swine «sve oh ace eons aoa eee 578
(a) The Neighbourhood of Derna.
(>) Derna to Cyrene.
(c) Mersa Susa (Apollonia) to Slonta.
(d) Slonta to Messa.
(e) Messa to Merj.
(7) Merj to Ptolemeta.
(g) Merj to Benghazi.
Li MAstsotWossile \.). s2iabs) 6c 594
iV. Classification and Correlation of the Cyrenaican Rocks 593
Vi... The Tectonic Geology: ..).u.. 0.6. a ee 603
VI. The Wadis, and Possible Variations in Pleistocene
Climate is53 heats stave... ute eeatgde Soke ee 608
Vit,’ Lhe Composition of the Soils 22.) .575-. S12eeese eee 612
VALE Summeary-ot Conelusions. %.....:.9--s-ces-eee eee 614

I. Intropvction.

CyreNnaica, a province of Eastern Tripoli, is the projection on the
northern coast of Africa between the Gulf of Sidra (the Greater
Syrtis) on the west and the Bay of Bomba on the east. The name
is sometimes used to include Marmarica and the Libyan coast, as
far as the still undetermined western frontier of Egypt; but the
restriction of Cyrenaica to the wide foreland occupied by the famous
Greek colony whose capital was Cyrene renders it a more natural
geographical division. Itis thus equivalent to the Gebel el Akdar—
the Green Hills—of Arab nomenclature ; while the Gebel el Akabah
—the Abrupt Hills,—its eastward continuation between the Bay of
Bomba and the Bay of Salum,’ is the plateau of Marmarica.
Cyrenaica, as thus restricted, is a land of great classical interest:
it includes the ancient Pentapolis; the city of Cyrene stood on the
northern edge of its plateau; and the Garden of the Hesperides and
the River Lethe lay in hollows in the limestone on its coastal plain.

1 The spelling of most of the Egyptian place-names is adopted from the
recent map of Egypt published by the Geological Survey of that country,

Vol. 67.] THE GEOLOGY OF CYRENAICA. 573

Cyrenaica is, however, geologically the least-known area on the
shores of the Mediterranean. The geology of the parts of Egypt
near the eastern frontier of Cyrenaica is known from the work of
Zittel’ and Fuchs? at Siwa, and from collections made on the coast
of Marmarica at Mersa Tobruk by Schweinfurth,’ and on the Libyan
coast by Ball* and by Pachundaki’ at Mersa Matruh, about half-way
between Alexandria and the Bay of Salum. The correlation of
the rocks on the eastern frontiers of Cyrenaica has been care-
fully discussed by Dr. Blanckenhorn.® An admirable summary of
the geological data regarding Cyrenaica was published in 1904 by
Dr. Hildebrand, who shows that the existing information was then
both scanty and uncertain.”

From the evidence available in 1908, three different explanations
of the geological structure of Cyrenaica were possible. It might be
a fragment of a mountain-loop that had once connected the Atlas
with the mountain-ranges of Crete and Asia Minor; or it might be
a plateau of Eocene rocks—an outlier of the Mokattam Series of
Egypt; or again, it might be a horst of Miocene and Pliocene lime-
stones, once continuous with those of Malta.

The first theory—the connexion between Cyrenaica and the
Atlas—was suggested by several considerations, including the
probability that the mountains of Cyrenaica had an axial core of
ancient rocks.

The first information as to the geological structure of Cyrenaica
was collected by Della Cella, an Italian doctor who accompanied a
military expedition led by the Bey of Tripoli into Cyrenaica in 1817.
Della Cella clearly recognized that the mountains of Cyrenaica were
not a simple continuation of the Atlas, though he regarded both
areas as composed of similar rocks. He remarks :—

‘In some of my letters, I have attempted to shew, that the mountains of
the Cyrenaica form no part of the eastern prolongation of that chain which

1 K. A. von Zittel, ‘ Beitrage zur Geologie & Palaontologie der Libyschen
Wiiste & der angrenzenden Gebiete von Aigypten’ Paleontographica, vol. xxx,
pt. 1 (1883) pp. exxiv—cxxxvi.

2 Th. Fuchs, ‘ Beitrage zur Kenntniss der Miocan-Fauna Agyptens & der
Libyschen Wiiste’ Jizd. pp. 18-66 & pls. vi—xxil.

3 G. Schweinfurth, ‘Hin Besuch in Tobruk an der Kiiste von Marmarica
Marineverordnungsblatt, No. 47 (1883) pp. 14-29. For reference to the
discovery of these fossils, see G. Hildebrand, ‘ Cyrenaika als Gebiet kiinftiger
Besiedelung’ Bonn, 1904, pp. 78-79, and M. Blanckenhorn, ‘ Neues zur Geo-
logie & Palaontologie AWgyptens, III. Das Miocan’ Zeitschr. Deutsch. Geol.
Gesellsch. vol. liii (1901) pp. 104-105.

+ Maps of the Districts of Mersa Matru & Ras Allem Rum ‘showing... and
the Main Outlines of the Surface-Geology ’—scale 1 : 25,000. Cairo, 1903.

> D—D. E. Pachundaki, ‘Sur la Constitution Géologique des Environs de Mirsa
Matrouh (Marmarique) ’C. R. Acad. Sci. Paris, vol. exxxvii (1903) pp. 850-51 ;
also ‘Contribution a ’Etude Géologique des Environs de Marsa Matrouh
(Marmarique)’ Revue Internationale d’Egypte, vol. iv (1907) 36 pp., pt. ii.

6 M. Blanckenhorn, ‘Neues zur Geologie & Palaontologie Hgyptens, II.
Das Paleogen’ Zeitschr. Deutsch. Geol. Gesellsch. vol. lii (1900) table facing
p- 406; and ‘IIT. Das Miocan’ bid. vol. liii (1901) table facing p. 52.

7 G. Hildebrand, ‘ Cyrenaika als Gebiet kinftiger Besiedelung’ Bonn, 1904,

pp. 77-95.
2R2

574 PROF. J. W. GREGORY ON [Nov. rgrz,

rises upon the northern border of the African coast, and extends from the
western shores of the gulph of the Great Syrtis as far as the kingdom of
Morocco; and my observations upon the termination of the gulph demonstrate
that there exists no such connexion. But this does not prevent the calcareous
constitution of Mount Atlas from forming also the character of the Cyrenean
mountains. I am unacquainted with the Atlantic chain of mountains to the
west of Tripoli, but I have seen several specimens of the rocks between Tripoli
and Tunis, and they display the same character and formation.’ !

He recorded the presence in Cyrenaica of many fossils different
from the existing Mediterranean fauna, and he described some of
the fossils from the mountains as ‘ presenting in their fractures
the character of Ammonites.’? It therefore appeared possible, from
Della Cella’s statements, that Cyrenaica might have a foundation of
Mesozoic rocks containing Ammonites.

The existence in Cyrenaica of Palaeozoic or pre-Paleeozoic cry-
stalline marbles seemed also possible. For, according to Della Cella,

“the heart of these mountains consists of a compact chalk which has the usual
hardness of all kinds of marble; and, though of secondary formation, and
bearing frequent traces of shells, its grain is fine and often glitters like saline
marble.’ (Op. cit. p. 116.)

The Italian traveller Camperio remarked® in 1882, that the
marble used for the statues at Cyrene might either have come from
the Greek islands or from the neighbouring mountains. The
statues, of which the British Museum has a valuable collection,
are of saccharoidal marble, and so also is the one specimen that I
have examined in the Louvre. Hence Capt. Camperio’s suggestion
of the local origin of this material was consistent with the
occurrence of a Palseozoic, or perhaps even older, formation in the
mountains of Cyrenaica.

Hamilton, in 1856, described the coast-hills from the Wadi Nagr,
where the track to Cyrene leads on to the plateau, past Derna
towards Ras el Tin, as composed of ‘barren sandstone, * and
Dr. Hildebrand’ quotes Meier-Jobst as asserting the occurrence of
:sandstone at Cyrene on the summit of the plateau. These reports
-suggested that sandstones might play an important part in the
~structure of Cyrenaica.

The geological evidence connecting the Cyrenaican mountains
~with the Atlas was indefinite; but it was supported by the con-

1 Paolo Della Cella, ‘ Physician Attendant on the Bey’: ‘ Narrative of an
“Expedition from Tripoli in Barbary to the Western Frontier of Egypt, in
1817, by the Bey of Tripoli; in letters to Dr. Viviani of Genoa, by...; with
an Appendix, containing instructions for navigating the great Syrtis.’ ‘Trans-
Jated from the Italian by Anthony Aufrere, Esq. London, 1822, pp. 165-66.

2 Ibid.p.165. The original of this passage is as follows: —‘ Talvolta trovasi
guarnita di piccoli testacei lentiformi, che nella loro spaccatura presentano i
-caratteri delle Ammoniti’ (Lettera xiii, p. 162).

3 Camperio, ‘ Una Gita in Cirenaica’ Esploratore, vol. vi, 1882, p. 16.

4 James Hamilton, ‘ Wanderings in North Africa’ 1856, p. 113.

5 G. Hildebrand, ‘ Cyrenaika als Gebiet kinftiger Besiedelung ’ Bonn, 1904,
ip. 86.

Vol. 67.] THE GEOLOGY OF CYRENAICA. 57

clusions of Sir R. Lambert Playfair, who, in his Presidential Address
to the Geographical Section of the British Association in 1890,
accepted Cyrenaica (from geographical considerations) as a detached
fragment of the Atlas Mountains,

‘The Atlas range’..., he states, ‘runs...through Algeria and Tunisia ; it
becomes interrupted in Tripoli, and it ends in the beautiful green hills of the
Cyrenaica, which must not be confounded with the oases of the Sahara, but is
an island detached from the eastern spurs of the Atlas, in the ocean of the
desert.’ (‘The Mediterranean, Physical & Historical’ p. 875.)

This view, however, has not received any recent support,’ and
Cyrenaica has been generally regarded as a plateau of Kainozoic
rocks. Thus Taramelli & Bellio, on their geological map of Africa,?
represent Cyrenaica as composed wholly of Eocene and Oligocene
formations ; they refer to the country as having been separated
from the older rocks of the Sahara by a Pleistocene sea, some of
the evidence for which they regard, however, as doubtful.

The occurrence of Eocene rocks in Cyrenaica appeared probable
from the identification of nummulitesinthem. Thus, the Archduke
Salvator? described the walls of the Cave of Lethe as composed of
‘Nummulitenkalk.’ Dr. Hildebrand* quotes astatement by Haimann
(‘ Cirenaica ’ 1886) that the mountains of Cyrenaica are formed of
an Eocene limestone full of nummulites. Hildebrand nevertheless
rejected the reported nummulites and Hocene beds as based on
unerliable evidence’; and, in regard to the rock at the ‘ River”
Lethe, his scepticism was justified, for it contains Orbitoides and
not nummulites. He expressed himself in doubt whether the
sandstones reported along the coast of Cyrenaica are the outcrop
of an Eocene base of the country, or whether, as he thought more
probable, they are a Pliocene or ‘ Quaternary’ series deposited upon
the flanks of the Miocene limestone (op. cit. p. 86). Hildebrand.
was quite correct in his view as to the recent age of the low-level!
sandstones; but, despite his remarkably thorough acquaintance:

1 Tt is, however, consistent with some recent topographical maps, as, for ex--
ample, C. Diercke, ‘Europa. Bodenverhaltnisse ’Schulwandkarten, 1: 3,000,000,
Brunswick.

2 T. Taramelli & V. Bellio, ‘Geografia & Geologia dell’ Africa’ Milan, 1890,.

Ie it.

3 [Ludwig-Salvator] ‘ Yacht-Reise in den Syrten, 1873’ Prag, 1874, p. 52.
Reprinted as ‘ Eine Yachtreise an den Kiisten von Tripolitanien & Tunisien.”
Woerl’s Reisebibliothek, Wiirzburg, 1890, p. 49.

4 G. Hildebrand, ‘ Cyrenaika als Gebiet kinftiger Besiedelung’ Bonn, 1904,

. 88.

: 5 ‘These two records’—those of Haimann and the Archduke—‘are therefore
for us especially important,’ says Hildebrand (‘ Cyrenaika’ 1904, pp. 83-84),
‘because they are in direct opposition to all others that we know. For there
is scarcely any mention of nummulites, which would certainly point to an old
Tertiary formation, and still less of formations of the Eocene time. These state-
ments as to age stand quite alone. Besides, they inspire no special confidence.
Haimann was neither geographer nor geologist, as may be recognized “‘ Schritt
und Tritt.” And the Archduke Salvator also makes no claim to geological
knowledge.’

576 PROF. J. W. GREGORY ON [Nov. 1911,

with the literature of Cyrenaica, he overlooked Admiral Spratt’s
account of the geology of Derna and the identification of a num-
mulite from Mersa Susa by the late Prof. T. Rupert Jones.

The most precise geological information regarding Cyrenaica was
given by Admiral Spratt!; but, as it was an Appendix to a book on
Crete, it has been overlooked. He contrasted the jagged mountains
of Crete with the plateaux of Libya extending from Tripoli to the
Nile; and he recognized the numerous sudden fiexures of the coast,
as in the Syrtis, the Gulf of Salum, and at Ras el Tin, as due to
faults. His most important contribution to the geology of Cyrenaica
was an account of the section at Derna, which he described as com-
posed of a lower series of white or cream-coloured limestones ‘ full
of nummulitic shells resembling those of Crete’ (op. cit. p. 377) ;
and this lower series, 250 feet thick, he described as passing
conformably upwards into yellowish marly sands or sandstone,
resembling the yellow sandstones of Malta and containing many
of the Maltese fossils. That Spratt’s foraminifera were really
nummulites cannot be doubted, as one specimen, now in the
(Natural History) British Museum, was identified as the Lower
Kocene Nummulites perforata.”

The identification of nummulites from Cyrenaica having been
overlooked or discredited, Cyrenaica has been generally described in
recent years as composed of a sheet of Miocene and perhaps also
Pliocene limestones. This view was expressed by Dr. Giirich,’ who
described the country as mainly Middle Miocene; and he appears
to exclude the possible occurrence of Oligocene deposits by reference
to the existence of an important gap in this region between the
Eocene and the Miocene. Zittel’ and Suess’ both also accepted
Cyrenaica as Miocene. Suess referred to it, though doubtfully, as
belonging to the second Mediterranean stage—that is, Upper or
Middle Miocene. This view was based on the collections made by
Schweinfurth at Mersa Tobruk, on the coast of Marmarica; and
in Suess’s sketch-map (loc. cit. fig. 41) the whole country is
represented as belonging to the Upper Mediterranean stage and
younger formations, while the later French edition by M. de
Margerie ® includes a map ‘after G. Rolland, in which the country
is all marked as Middle Miocene. According to the last statement
on the subject, issued in 1907 by M. D. E. Pachundaki,’ the

17. A. B. Spratt, ‘Travels & Researches in Crete’ vol. ii (1865) app. iv,

. 375-80.
Pr T. R. Jones, ‘ Catalogue of the Fossil Foraminifera in the British Museum
(Nat. Hist.)’ 1882, p. 45.

3 G. Girich, ‘ Ueberblick tiber den geologischen Bau des afrikanischen Kon-
tinents’ Petermann’s Mitteilungen, vol. xxxiii (1887) p. 261 & pl. xiii.

+ K. A. von Zittel, ‘ Beitrage zur Geologie & Palaontologie der Libyschen
Wiiste’ Paleontographica, vo]. xxx (1883) pp. xxvi—xxvii & exxxi.

5 KE. Suess, ‘Das Antlitz der Erde’ vol. i (1885) p. 465.

° «La Face de la Terre’ vol. i (1897) pp. 459 (fig. 68) & 464.

‘ D. E. Pachundaki, ‘Contribution 4 /Etude Géologique, des Environs

de Marsa Matrouh (Marmarique)’ Revue Internationale d’Egypte, vol. iv
(1907) p. 8.

a

Vol. 67.] THE GEOLOGY OF CYRENAICA. 577

conclusion of Zittel as to the age of the ‘Plateau Marmarico-
Cyrenaique’ had been confirmed.

With such an array of authority in favour of the Miocene age of
the rocks, it is not surprising that the ‘Carte Géologique Inter-
nationale de l’Europe’ (Sheet D vii), issued in 1905, colours the
whole of Cyrenaica as Miocene, except for a band of recent forma-
tions along the coast and in some of the wadis, and a strip of
‘ Quaternary ’ running inland from Benghazi to the Wadi el Bal,
as also an area of the same age beside the Gulf of Bomba.

The scantiness of available information as to the geology of
Cyrenaica is due to the country having been closed to travellers,
especially during recent years, by the Turkish authorities. Most
of those who have visited Cyrenaica have been archeologists,
whose attention has been engaged by its numerous antiquities,
or Italian explorers interested in its commercial resources and its
suitability for Italian colonization.

In 1908 I had the opportunity of visiting Cyrenaica as leader of an
expedition sent to investigate whether the country would be suitable
as a colony for Jewish refugees.* In spite of the support and the
firman of the late Redjeb Pasha, then the enlightened Governor of
Tripoli, the conditions were not always favourable to geological
survey. Moreover, as we landed at Derna on July 24th, 1908, and
arrived at Benghazi on August 14th, after a march, including excur-
sions off our main route, of about 300 miles, the geological study
of the country was only in the nature of a rapid reconnaissance.
1 should have liked to go eastwards in the direction of the Egyptian
frontier, to trace the connexion between the rocks of Cyrenaica
and the Miocene limestones of Western Egypt and Marmarica ;
but I had pledged my word to Redjeb Pasha that we would not
go farther east than could be managed in one day’s journey from
Derna.

After engaging a camel-caravan at Derna, and having been supplied
with an escort by the officer in command of the Turkish garrison,
we marched overland across the plateau of Cyrenaica to Benghazi
on the Great Syrtis; we supplemented this traverse by excursions
northwards to the coast and southwards to the open plains, as far as
was allowed by time, water-supply, and the Turkish permission.

I have to express my great indebtedness for the opportunity of
the journey across Cyrenaica to Mr. Israel Zangwill, who arranged
the expedition and secured the consent of the Turkish authorities ;
also to my companions Mr. M. B. Duff, Dr. M. D. Eder, Dr. J.
Trotter, and Prof. M. N. Slousch, for the pleasure of their company

' J. W. Gregory, ‘Report on the Work of the Commission sent out by the
Jewish Territorial Organization under the Auspices of the Governor-General
of Tripoli to Examine the Territory proposed for the Purpose of a Jewish
Settlement in Cyrenaica.’ The report includes an Introduction by Israel
Zangwill; an Agricultural Report by J. Trotter; a Report on the Water-
Supply and Engineering by R. E. Middleton, W. Hunter, & M. B. Duff ;
a Medical Report by M. D. Eder; and an Appendix by Prof. N. Slousch,
52 pp., 3 maps, 14 pls. London, 1909.

578 THE GEOLOGY OF CYRENAICA. [Nov. 1914:

and the benefit of their indefatigable co-operation. They collected
many of the fossils, and to Mr. Duff is due the map of our route,! on
which the geological map (Pl. XLII, fig. 1) is based. I have also to
express my thanks to Mr. Justin C. W. Alvarez, our Consul-General
at Tripoli, and to Messrs. R. A. Fontana and G. Farrugia, the
British Consuls at Benghazi and Derna, and to M. Jacoub Krieger,
the confidential secretary to the late Redjeb Pasha, for his unfailing
courtesy and help.

I am greatly indebted to Mr. R. B. Newton for the care with
which he has studied the fossil mollusca collected by the expe-
dition, and the accompanying memoir onthem. I am also indebted
to Mr. F. Chapman for his report on the foraminifera, and to
Mr. D. P. Macdonald for his careful microscopic examination of the
limestones. Dr.C. W. Andrews has kindly helped me with reference
to the literature on the fossil mammalia of the adjacent areas.

The magnetic variation in Cyrenaica was taken as 6° W.

For the literature on Cyrenaica, reference may be made to two
chief bibliographies—R. L. Playfair, ‘The Bibhography of the
Barbary States: Part I, Tripoli & the Cyrenaica’ Roy. Geogr.
Soc., Supplementary Papers, vol. 11, pt. 4 (1889) pp. 559-614;
and G, Hildebrand, ‘ Cyrenaika als Gebiet kiinftiger Besiedelung’
Bonn, 1904, pp. 329-78.

Il. Frerp-OxpskRvATIONS.

(a) The Neighbourhood of Derna.

Derna is situated on a delta-fan of limestone-gravel at the mouth
of the Wadi Derna. The gardens in the town are irrigated by
water from springs at Seghia and Bonmansur, respectively about
4 and 53 miles up the wadi. The river-bed is covered by coarse
Jimestone-shingle, and is usually waterless. It forms, in fact, the
main thoroughfare through the town. Above Derna the river
emerges from a deep gorge, and near its mouth is a bank of tufa,
which rises to the height of 100 feet up the eastern side of
the wadi: it consists of successive layers of calcareous sand,
of tufa largely composed of cylindrical fragments, and of rolled
limestone boulders. This deposit obviously represented a delta-fan
which had been formed at the mouth of the wadi, before the gorge
had been corroded to its base-level. The material was due to the
alternate deposition of coarse shingle during floods, and of tufa
during intervals when the only water came from adjacent springs.

The sections along the Wadi Derna expose two main rocks: the
lower part of the cliffs consists of a soft white to cream-coloured
limestone, crowded with large flat nummulites, and similar to the
typical Nummulitic Limestones of the Mokattam Series of Egypt.

According to Mr, Chapman, the foraminifera, which are unusually
well preserved, are of Middle Eocene age. The most characteristic

1 [A MS. copy of the map will be placed in the Society’s Library.] _

.
S
Lan
_~—
~
=

3
i

6
stone.

6d = Pecten-arcuatus Lime-

< Coral Limestone

Friable limestone with Operculina
lybica and Nummulites curvispira.

Sandy nodular limestone.

6¢

1 inch= 1 mile.]
6a

[Horizontal scale :
Massive coral-limestone.
Nummulitic limestone.

ef)
fa
L

Plain extending 10 miles
Southwards to the foot of Gebel Feteha.

Upper Hocene (Slonta Limestones)

Fig. 1.—Section drawn southwards from a point about 6 miles south-east of Derna ; approwimate length
Derna Limestones (Middle Eocene).

Limestone with Schizaster ederi (Aquitanian)

300 -
100 -

U
o
oO
ie)

Feet
800

4
8

ment dm lie
ene.

species is Nummulites (Pa-
ronia) curvispira Menegh.*
Old rock-dwellings have
been excavated in this
rock, which extends up the
wadi as far as we could
see. It includes layers of
broken _ shell-fragments
and echinoid spines, and
some layers, as at Seghia,
of pinkish limestone full of
N. curvispira and NV. ehren-
bergt, 2 inches in diameter.
This cream-coloured lime-
stone and its associated
beds, which may be grouped
together as the Derna
Limestone, are some 250
feet thick. This series is
covered by harder lime-
stones, which weather
brown and are more con-
spicuously stratified. They
are over 200 feet thick
at Derna, and from their
great development at
Slonta are subsequently
referred to as the Slonta
Limestones.

About 6 miles from
Derna the wadi divides at
the springs of Bonman-
sur; a platform composed
of 20 feet of calcareous
sands and gravels, inter-
bedded with layers of
travertine from 1 to 3 feet
thick, separates the two
branches of the valley.
The face of this platform
is covered by a sheet of
calcareous tufa with many
fantastic projections. The
sands contain shells, which
have been identified by
Mr. R. B. Newton as Hy-
gromia sordulenta (More-
let), showing the age to be

1 In the following pages
any foraminifera the species of
which are mentioned have been
determined by Mr. Chapman,

and similarly the mollusca by
Mr. R. B. Newton.

580 PROF, J. W. GREGORY ON [Nov. rgrr,

Pleistocene. The surface of the platform is strewn with so many
palzolithic chert-implements, that it was probably the site of an
ancient camp.

The stratigraphical relations of the Derna Limestone are shown
by a section across the face of the plateau, about 5 miles south-east
of the town, from an ancient megalithic ruin known as Gasr el
Harib to the wells at Bint. The ruin stands at the height of
700 feet near the northern edge of the plateau, which extends far
southwards, to the foot’of the hills of Gebel Feteha. The northern
face of the plateau shows a good section, illustrated by fig. 1 (p. 579).
The lower part of the main scarp, up to the height of about
260 feet above sea-level, consists of the cream-coloured Derna
Limestone; this is overlain, at the height of 340 feet above sea-
level, by a sandy foraminiferal limestone, from which Mr. Chap-
man has identified fourteen species of foraminifera, including
Nummulites curvispira and Operculina libyca.

Above this foraminiferal bed follow 60 feet of the brown-
weathering, well-bedded limestones; they end above in a hard
rock containing reef-building corals. This coral limestone forms a
shoulder on the scarp, surmounted by a megalithic ruin. Above
this point there is a more gradual ascent on to the plateau, up a
valley cut through a series of massive rough-weathering limestones,
and having on its floor some ancient wells from 30 to 40 feet deep,
still used by the Arabs. Upon the plateau are some hills of a soft,
marly, friable limestone of a pale buff colour, resembling some layers
of the Globigerina Limestone of Malta; it yielded a Schizaster
which, although too crushed for certain specific determination,
resembles Schizaster ederi, sp. nov.

The main sequence in this section is, therefore, from a limestone
which is probably Aquitanian, through the Slonta Limestones, down
to the Derna Limestones. At the foot of the main scarp is a belt
of limestones, one of which, at 200 feet above sea-level, yielded a
fossil determined by Mr. Newton as the Priabonian Pecten arcuatus
Brocchi, and consequently belonging to a horizon much higher than
the rocks level with it in the cliffs on the south. The steep scarp
south-east of Derna is, therefore, probably a fault-scarp, and the
foot-hills at the coast are composed of the downthrown Slonta
Limestones. I had, however, no opportunity of collecting further
specimens from this area, or of completing the section to the sea.

(6) Derna to Cyrene.

We marched from Derna for about 6 miles westwards along the
coast, crossing a belt of shore-deposits and delta-fans, which sloped
up from the sea to the foot of the plateau-scarp. Along the lower
part of the cliff could be seen the cream-coloured Derna Limestones,
capped by the bedded, brown-weathering limestones. In a wadi
about 3 miles west of Derna, the limestones on the coastal plain
dip 5° northwards. Outcrops of a chalky limestone containing flint
nodules occur to the west of a wadi, about 4 miles from Derna, and

Vol. 67.] THE GEOLOGY OF CYRENAICA. 581

form a small hill between the path and the shore. This chert-
bearing rock is also well exposed in the banks of the Wadi Nagr,
where it is represented by a soft chalk-like limestone with lines
of flat chert-nodules, dipping 5° northwards. This chert-bearing
limestone extends along the foot of the cliffs, to the west of our
camp.

West of the wadi, Dr. Trotter collected a fossil which Mr. Newton
has determined as Lucina cf. nokbahensis Oppenh., in a limestone
free from Nummulites. If this specimen were zm situ, then, as at
Bint, east of Derna, Upper Eocene rocks are faulted down at the
foot of the plateau-scarp.

Fig. 2.—Section in the plateau-face at Wadi Nagr,
west of Derna.

— 800
ma ie one pe
ithothamnion Linestone
Ae a hite Limestone 7
One with Orthophragmina pratti
— 500
White Derna Mi

imestone with
mmutlites gizehensis

Nu

SSS

Chalky limestone with chert- nodules

The sequence of the rocks in this district may be observed in the
ascent of the Okbah or Aukubah, the Arab name for the cliff which
forms the northern face of the plateau. The rocks are well exposed
there, except that some bands are covered by an efflorescent lime-
stone-crust. The chalky chert-bearing limestone passes gradually
up into a harder limestone with chert-nodules, which is succeeded
by the cream-coloured N.-curvispira Limestone: this, being very
soft, has been carved into caves, and is in places overhung by the
rock above. At about 500 feet above sea-level the slope becomes
steeper, up a cliff of the brown-weathering limestones (the Slonta
Limestones), which begin with a layer of limestone full of small
foraminifera, succeeded by a white limestone with Orthophragmina
prattt and Operculina, which continues up to the height of about
_630 feet. It is succeeded by a pinkish limestone, 30 feet thick,
containing nullipores and some foraminifera, among which Mr.
Chapman has identified Nummulites curvispira and Truncatulina ;
so he refers the brown limestones to the Middle Eocene. At 660
feet isa band of white marl, followed by the typical brown-weather-
ing limestone, which continues to the edge of the plateau at about
750 feet. (See fig. 2, above.)

>

582 PROF. J. W. GREGORY ON [Nov. 1911,

From the edge of the plateau above the Wadi Nagr the country
rises gradually westwards and southwards, although the surface is
broken by deep wadis. The Slonta Limestones, containing occasional
shelly horizons, form the surface of the plateau. The dip is slight
and to the north. A limestone with casts of reef-building corals
occurs at the height of a little over 1100 feet, about 7 miles west of
our first camp. A short distance farther west we saw exposures of
a soft yellowish limestone, which we had the best opportunities of
examining in the wells near an Arab burial-ground known as
Birlibah. Here I found an echinoid, Hypsoclypeus hemisphericus
(Greg.), the first Miocene’ fossil found.

From Birlibah to Gubah, a distance of about 12 miles, the
country is thinly wooded moorland. It rises gradually from 1100
to 1800 feet; the rocks are yellowish granular limestones, with
some nodular, marly seams, which, especially near Wadi Umzigga,
form a number of small springs. The characteristic fossil is a large
pecten, which Mr. R. B. Newton has identified as Oopecten rotun-
datus (lam.). The fossil mollusca collected at the Wadi Umzigga
and seen at other adjacent exposures, indicate that these limestones
are not lower than Aquitanian ; and, according to Mr. Chapman, the
limestone at Wadi Umzigga is full of Lepidocyclina elephantina
Mun.-Ch., and is Aquitanian or Stampian. The age of the Wadi-
Umzigga beds may, therefore, be regarded as Aquitanian.

At Gubah, beside the ruins of a Greek bath, we found some
fossils, among which Mr. Newton identified Strombus coronatus
Defr., Alectryonia plicatula (Gmel.), and the cirriped Balanus con-
cavus Bronn. He therefore assigns the rock to the Upper or Middle
Miocene. After leaving Gubah, we ascended another platform about
100 feet high, formed of a rough-weathering limestone; but, as we
were passing close beside a Senussi settlement, Zawiah Charrah,
we had no opportunity of collecting fossils until 6 miles from Gubah,
when we reached the ruins of the Roman town of Lamludeh (the
ancient Lebdis). There we found some casts of lamellibranchs and
a large gastropod, weathered out of beds of earthy limestone and
marl: these fossils, according to Mr. Newton, indicate an Aquitanian
age. West of Lamludeh the ground is rocky, and much of it is
covered with scrub growing in the depressions between hummocks
of a hard, white limestone, containing many large Ostreids, including
Ostrea crassicostata Sow. Immediately west of Zawiah Turt is an
exposure of a limestone containing many echinoid plates and fora-
minifera, and an associated limestone yielded an Amphiope.

At Labruk, 10 miles west of Lamludeh, the earthy limestones, like
those at Lamludeh, crop out north of the track; close beside the
water-hole is a band of hard limestone containing casts of reef-
building corals. About half a mile west of Labruk is a bed con-
taining many specimens of Echinolampas.

A waste of rocky scrub and rough hills of coral-limestone, with
the Echinolampas Bed cropping out in the depressions, extends
for 6 miles from Labruk to the marabut or shrine of Sidi Dia-

1 For the accepted limit of the Miocene, sce p. 593.

Vol. 67.] THE GEOLOGY OF CYRENAICA. _ 583

siasia (or Sidi Jaja). From our camp there we visited Safsaf,
some bare limestone-hills used by the Romans as a collecting-ground
for water, which was carried by an aqueduct to the city of Cyrene,
6 or 7 miles distant in a direct line. The same hard Slonta Lime-
stones, which weather irregularly, occur north-west of Sidi Rof

- Diasiasia ; they pass in that direction under a series of soft, earthy,
white and grey limestones and marls. These rocks form the hills
over which are scattered the widespread ruins of the city of
Cyrene. The rocks agree lithologically with those of Lamludeh
and the fossils collected show that the Cyrene Limestones are of
Aquitanian age.

(¢) Mersa Susa (Apollonia) to Slonta.

It was necessary for our work to determine the conditions which
control the water-supply of the district near Cyrene and the chances
of finding situations suitable for storage-reservoirs. Hence we
made a north-and-south traverse across the country from the sea at
Mersa Susa (Apollonia) through Cyrene, to the southern downs at
Slonta. This section (fig. 3, p. 584) illustrates the general geological
structure of that part of Cyrenaica.

The city of Cyrene stands at the height of about 1950 feet above
sea-level, on the northern edge of a plateau which rises gradually
southwards to 2700 feet near Slonta. Immediately north of Cyrene
is a steep cliff, which falls to the level of about 1300 feet, whence
a platform, generally referred to as the ‘lower plateau,’ extends
for about 3 miles northwards, and from its edge, at the height of
about 1000 feet, the steep lower cliff falls abruptly to the shore.
The lower cliff, being the extension of the cliff near Mersa Susa,
may be a fault-scarp; it was, therefore, necessary to consider
whether the upper cliff at Cyrene was of the same origin. This
view appeared the more possible, as a little below the Fountain of
Apollo is a white soft limestone, containing nummulites indis-
tinguishable in the field from those in the similar rock of the
Derna Limestone, which is exposed in the upper part of the lower
cliff. I could, however, find no repetition of the Echinoid Lime-
stone, which overlies the Derna Limestone, above the upper nummu-
litic limestone, and was accordingly forced to reject the possibility of
the two similar nummulitic limestones being the same bed repeated
by faults. This conclusion is supported by Mr. Chapman’s identifi-
cation of the characteristic foraminifer of the upper limestone as
Nummulites gizehensis var. lyelli ; while that found in the Derna
Jamestone is the typical form of the species. The upper cliff,
moreover, has the characters of an escarpment, and not of a fault-
scarp: it has been cut back into numerous gullies, and projects
between them in irregular spurs. The uneven escarpment-like
weathering of the cliff is well shown in the plan of Cyrene by
Smith & Porcher.’

1R. M. Smith & H. A. Porcher, ‘History of the Recent Discoveries at
Cyrene’ 1864, pl. xl.

a

distance = «about gt mules.

Fig, 3.—Section from Slonta through Cyrene to the sca :

The series is, therefore,
a steadily ascending one
from Mersa Susa to Cyrene.
The old port of Mersa

S
= Susa is built on a series of
> dune-limestones, behind
~ ‘'$ which is an alluvial delta
deposited by the Wadi Susa.
& The route to Cyrene goes
= westwards across the allu-
S vial deposits for about a

mile; and then, in the
banks of a large wadi,
limestone is exposed dipping
5° northwards and contain-
ing Gisortia gigantea Munst.,

o

S *

g. We wi ele A Trachycardium cf. granco-
O nense Oppenh., and Pecten

arcuatus Brocchi. Mr. New-
ton, therefore, refers this
limestone to the Priabonian.’
At the foot of the plateau
the cherty limestones—the
Apollonia Limestones—are
exposed, and they continue
up the track from 150 to
530 feet above sea-level.
This limestone, as a rule, is
massive, and contains many
foraminifera and some shell-
fragments. Some indeter-
minable molluses were col-
lected at the height of 450
feet in a band of cherty
limestone. Thechert-bearing
series ends at the height of
530 feet witha chert-breccia.

Fihularia and Echinoid Limestones.
Derna Limestones, with Nwmm

9= Apollonia Limestones.

7
8

4.
qt,

ehensis, var. lyelli.

~
ow

&
3
ce |
BS Above this follows the
Fx’> compact, creamy - white
oe Derna Limestone, full of
Z2& - Nummulites curvispira and
& == identical in character with
z BB that so well exposed at
AGE Derna. At 600 feet is a.
2. white, foraminiferal lime-
S TP Ss . . id f
S= stone with echinoid frag-
Seq ments. At 620 feet is an

oolitic band, also observed at

~ Wud ° iti °
ae. 2 ey @ a corresponding position in
2S re) re) (o) é

BS a ee the section above Ptolemeta.

‘ The specimen determined as Nummulites perforata by the late Prof. T.
Rupert Jones from Mersa Susa doubtless came from the same limestone, with
which it agrees lithologically. Mr. Newton has kindly examined it, and is
disposed to regard it as NV. intermedia, an Upper,Eocene species.

Vol..67.] THE GEOLOGY OF CYRENAICA. 585

The limestone at the level of about 900 feet is soft, and has been
excavated for cave-dwellings. It passes, apparently gradually, into
the hard, brown-weathering limestones; they form the surface of
a wide plateau, which rises slowly inland to the foot of the upper or
Cyrene Escarpment. At the level of 1100 feet, in the lower part of
these limestones, is a layer crowded with scattered echinoid-plates.

This lower plateau has a rough, irregular surface with many
limestone-hummocks, and small patches of thin soil in the hollows
between them. ‘This limestone continues past Ain Hafra, where it
yielded the Priabonian Luspira possaguensis Oppenh., and forms
the surface of the ‘ lower plateau’ directly to the north of Cyrene.
The section there begins on the north with the Echinoid Limestone
at the height of about 1100 feet; it underlies a white hard lime-
stone, which weathers very irregularly and forms the foundation of
the plain covered by sandy alluvium north of Cyrene. At the
base of the cliff which leads to the upper plateau is a limestone
containing the Middle Eocene echinoid Fibularia luciani and
Nummulites curvispira ; it crops out at the height of 1215 feet.
This rock is succeeded by a shelly limestone containing many
nummulites, including NV. gizehensis var. lyelli. The upper part
of this ‘lyellc’ limestone yields a few specimens of Echinolampas,
one of which was collected from the height of 1320 feet; and the
tombs of the northern necropolis of Cyrenaica have been mostly
excavated in the beds of this soft foraminiferal limestone, which are
interstratified with the harder bands.

The limestones used for the tombs are succeeded by a marly
limestone, which is full of irregular nodules and many flattened
stem-like fragments, and contains grains of glauconite. This bed
has an irregular horizontal lamination, which helps to render it
relatively impermeable to water sinking downwards through the
overlying porous jointed limestone. This layer accordingly throws
out a series of springs along the face of the escarpment. The most
famous is the ‘ Fountain of Apollo’ (or Ain Sciahat), at the height of
about 1760 feet above sea-level. The limestone above the Fountain
of Apollo is massive and contains some reef-corals, and it passes into
a soft earthy limestone containing layers of marl and many pectens,
identified by Mr. Newton as Mquipecten zitteli Fuchs, 4. cama-
retensis (Font.), . scabrellus (Lam.), Pecten vezzanensis Oppenh.,
ete.: the horizon is, therefore, Aquitanian. This Pecten Bed and
the limestone above it also yielded some echinoids, including one
which, though imperfect by reason of weathering, I had no hesitation
in identifying from its characteristic form as Hemiaster scille.
According to this identification, the echinoids agree with the mollusca
in demonstrating the Aquitanian age of the Cyrene Limestones.

The general dip of the rocks in this area is slightly northwards,
but occasionally it is reversed, and in the hill-face east of Ain Sciahat
is a clear dip of 3° southwards.

The hills south of Ain Sciahat, between it and the upper
part of the wadi of Bil Ghadir, the next wadi to the west, consist
of the Cyrene Limestones, with the spring-forming marl at their

086 PROF. J. W. GREGORY ON [Nov. 1911,

base. The upper part of that wadiis a deep ravine, cut by the
recession of a waterfall which exists only in the rainy season. -
Above the fall the valley continues as a wide dale, on the floor of
which are exposures of the limestone that overlies the nodular seam
of the Fountain of Apollo, The Cyrene Limestones extend for
about 2 miles to the south, and then, after crossing a flat-floored
valley covered with a sheet of alluvium about a mile in length, the
ground rises to scrub-covered hills of the hard Slonta Limestones.
The Echinolampas Bed occurs at a well known as Bir-Hu, at the
height of 2020 feet. The country is intersected by a series of deep
ravines, and water must be more easily obtained here than in most
parts of Cyrenaica. About a mile south of Bir-Hu isa ridge capped
by the Cyrene Limestones, and on the lower ground to the south
the rough-weathering hummocky lmestone containing casts of
shells and Echinolampas crops out at Gaafs-a-mudi. At the height
of 2200 feet in the Wadi Firyah, above the horizon of the EHchino-
lampas Bed, is a limestone full of reef-building corals. A little
farther south, at the height of 2470 feet, we crossed the divide be-
tween those streams the beds of which descend northwards through
the Wadi Firyah and those that begin their course southwards in
the direction of Slonta. At the height of 2350 feet is a well, in
which the water is upheld by a laminated sandy limestone con-
taining flattened stems like that at Ain Sciahat. It yields many
shell-fragments. The limestone above it yields the same pectens
as at Ain Sciahat, and also Ostrea crassicostata G. B. Sow.; it is
evident, therefore, that the beds are of Aquitanian age.

This outlier of the Cyrene Limestones is about 3 miles wide, and
it is succeeded on the south by the nummulitic Slonta Limestones,
which are much harder and weather brown. They contain, as
below Ain Sciahat, NV. gizehensis var. lyell1, and many specimens of
NV. curvispira, the latter of which, however, occurs also in the Derna
Limestones. I did not see the coral-limestones which usually mark
the upper bed of the Slonta Series, probably owing to the enforced
quickness of our march. The Slonta Limestones here form open
treeless downs extending as far southwards as we could see. The
Echinolampas Bed occurs on the summit of some of the hills near
a conspicuous landmark, the shrine of Sidi Mahomet Mahridi, as
also at the old Roman cisterns near Slonta.

A few Arabs were living at Slonta, and I endeavoured from them
to learn the nature of the country farthersouth. North of the shrine
of Sidi Mahomet Mahridi we had crossed a slight ridge at the height
of 2600 feet above sea-level; the well at Slonta is at 2400 feet,
and the country apparently has a long gradual slope southwards.
According to the sketch-maps of this district, the Cyrenaican plateau
descends to the Siwa-Aujela depression in two abrupt steps. But,
according to the Arabs, the acai sinks gradually into the plains
to the south.

Vol. 67.] THE GEOLOGY OF CYRENAICA. 587

(d) Slonta to Messa.

From Slonta we marched northwards up a picturesque dale. cut
through well-stratified limestones, which are either horizontal or
have a dip of about 1° to the north. The rocks included a bed
yielding Hchinolampas, bands with small nummulites, and some
containing a large nummulite 2 inches in diameter. We camped
beside a Roman fort at Shermatu, and thence descended into the
deep ravine of the Wadi Khumas near its head. This wadi descends
to the north: its cliffs at first consist of the brown-weathering
stratified Slonta Limestones; but farther north the cream-coloured
Derna Limestones, presenting the same characters as at Derna and
south of Mersa Susa, appear from beneath the upper series. The
Derna Limestone cropped out from the level of 1860 feet in the upper
Wadi Khumas down to 1240 feet. As the top of this formation
near Mersa Susa, 18 miles away to the north-east, is at 1000 feet
above sea-level, the dip of the rocks in this part of Cyrenaica must
be 1° downwards to the north-east.

We descended the Wadi Khumas for 4 miles and left it where, at
the level of 1240 feet, it turned westwards ; we rode up a tributary
gully on to the Messa plateau. The top of the cream-coloured
Derna Limestone in this gully is at a little over 1300 feet, and the
brown stratified Slonta Limestones, containing mollusca identified
by Mr. Newton as Lucina cf. pharaons Beliardi, Mactra cf.
fourtawi Cossm., and Cardita cf, acuticostata (Lam.), extended from
that level to the summit at 1640 feet. Our path joined the main
track from Cyrene to Messa near a well, at the height of 1520 feet,
in a stratified limestone which contains some clay and flattened
stems, and thus resembles the impermeable layer of the Fountain of
Apollo. The adjacent limestones yielded Hehinolampas chericherensis,
a species characteristic of the upper part of the Slonta Series.
Thence we crossed a rough limestone-ridge and descended to Messa,
where there are several springs produced by the laminar limestone
with stem-like fragments. Owing to lack of time, I was unfortu-
nately unable to continue the section from Slonta through Messa to
the coast.

(ec) Messa to Mer}.

At Messa we joined the track from Cyrene to Benghazi. The
wells at Messa are among the most important in Cyrenaica. They
lie on the floor of a deep valley, and are maintained by drainage
from the limestone around. The supply seems to be unfailing, and
is sufficient for the irrigation of some gardens. The adjacent ruins
show that the wells were important in ancient times. On leaving
Messa we climbed on to the plateau, and crossed for 3 miles
serub-covered limestone moors to the shrine of Abdul Wahil.
Thence we descended a steep path into a tributary of the Wadi
Jeraib (or Wadi Ishgerib, or Jerib), and we followed the tributary
until it joined the main valley. The cliffs of the Wadi Jeraib are in

CGS, No.Z6s, 28

588 PROF. J. W. GREGORY ON © [Nov. 1911,

places almost vertical, and they consist in part of the cream-coloured
Derna Limestone. Farther down the wadi the cliffs increase to the
height of about 400 feet, and the Derna Limestone is doubtless
capped by the Echinoid Limestone, as fallen blocks of this rock lay
at the foot of the cliff. We descended the Wadi Jeraib to the level
of about 820 feet, when it bent round to the north-east.. There
was no sign, even in the lowest part of the wadi, of the chert-
bearing limestones. Leaving the main valley, we ascended a
tributary to the south-west; we crossed the Echinoid Limestone
above the Derna Limestone, and reached the surface of the plateau
in front of the Roman castle, Gasr el Migdum. A limestone com-
posed of reef-building corals crops out beside it, and on the west of
it is a limestone containing small quartz-pebbles. The rocks in this
area and for some distance westwards include more mechanically
derived sediment than those farther east, and the ground is often
covered by a white residual clay. From Gasr el Migdum we
marched for 30 miles over an undulating limestone-plateau ; the
original surface varied in level from 1400 to 1500 feet, but it has
now been dissected, by the excavation of numerous valleys, the
floors of which are at the level of 1200 or sometimes of 1100 feet.
The country is a wilderness of scrub, which became denser as we
approached the Wadi Gharib.?. The few fossils found included a
large gastropod from below the shrine of Sidi Abdullah, identified
by Mr. R. B. Newton as Hippochrenes ampla (Sol.), which we also
found on the plateau south-east of Messa. ‘This fossil and an occa-
sional Echinolampas show that the rocks are of Upper Eocene (Pria-
bonian) age. ‘The last Echinolampas was found 6 miles east of
the Wadi Gharib: but, as in that district we were marching in single
file through dense scrub, we could not make any effective search for
fossils. The valley of the Wadi Gharib shows fine sections of
stratified foraminiferal limestones, resembling those of the Slonta
Series. The rock-exposures, however, were covered with a crust of
efflorescent limestone, and when this layer was broken through the
fossils seen were indeterminable casts ; but it was dark before there
was an opportunity of searching the rocks, and we had to resume
our march at dawn next morning.

We continued across the plateau of scrub-covered limestone, until
we reached an alluvial plain at Bigratah or Bugrat; the hillsides
around the plain consist of the cream-coloured Derna Limestone

1 The Admiralty Chart represents this wadi as part of a basin of interna
drainage, and separated from the sea by a continuous ridge from Messa to Gasr
el Migdum. Judging from the levels, the Wadi Khumas probably joins the
Wadi Jeraib above the confluence with the wadi from the shrine of Abdul
Wahil, and both should discharge northwards ; otherwise, it seems improbable
that the route should descend into the Wadi Jeraib, instead of keeping on the
plateau to the north of it.

2 We were assured that there was no water between Messa and Merj, except
for some small wells in the Wadi Gharib. The Commandant of the Turkish
garrison at Messa kindly sent a camel laden with water with us to Gasr el
Migdum, to save us from drawing on ourown loads. The few Arabs remaining
in this district were said to live on scanty supplies of stored water,

Vol. 67.] THE GEOLOGY OF CYRENAICA,. 589

yielding the large Nummulites curvispira. The track from Bigratah
to the plain of Merj crosses a low pass at the height of 1120 feet
above sea-level, where the chert-hearing lmestones crop out from
beneath the Derna Limestones.

The plain of Merj is an alluvial plain exceeding 50 square miles
In area; it is bounded on the south-east by an escarpment of the
Derna Limestone resting upon the chert-bearing limestone. The
town of Merj (generally regarded as the ancient Barca‘) is situated
on a small rise, due to the outcrop of a Priabonian limestone.
The plain is bounded on the south-east by a long straight cliff,
which has a trend of 52°, and is continued south-westwards along
the plain of Silene. ‘This long scarp is formed mainly of Derna
Limestone: the cherty lmestone is exposed beneath that rock in
the north-eastern part of the scarp, near Bigratah. The beds are
here dipping south-westwards so that the chert-bearing limestone
disappears below the surface; the beds then become horizontal,
and then dip south-westwards to a low syncline, of which the axis
meets the scarp south-south-east from Merj. Some 5 miles south-
west is another low anticline; it is followed by another syncline,
and the dip continues to the north-east as far as the wide breach
in the fault-scarp made by the Wadi Jebril. So far as I could tell
from a distant view, the beds again dip south-westwards, become
horizontal, and then the scarp becomes quite low. A higher
scarp could be seen behind it, and, judging by its white face, it
may also be formed of Derna Limestone.

The long cliff that forms the south-eastern boundary of the
plains of Mer] and Silene has the aspect of a fault-scarp, for it is
remarkably straight in direction ; the only projections from it are
talus-fans opposite the wadis; there are no spurs or outliers, such
as would be expected in an escarpment due to denudation ; and its
course is not affected by the changes of dip in the limestone.

That this hill-line is a fault-scarp is also shown by the palonto-
logical evidence. The limestone at the wells of Mer] contains
Pecten arcuatus Brocchi, Lucina cf. pharaonis Bellardi, and Vulsella
crispata Fischer, and, according to Mr. Newton’s determinations, is
therefore Priabonian, The characteristic nnmmulite of the Wells
of Merj is identified by Mr. Chapman as J. gizehensis var. lyelli,
whereas the species in the cream-coloured limestone of the Merj
scarp 1s LV. gizehensis typica. Hence the evidence of the foramini-
fera agrees with that of the mollusca, that the limestones at Mer),
which occur at levels ranging from 835 to 850 feet, belong to a
higher horizon than the limestone at the level of 1000 to 1240 feet
in the hills, 2 miles south of the town.

1 Barca, however, was at Ptolemeta, according to Smith & Porcher, ‘ History
of the Recent Discoveries at Cyrene’ 1864, p. 4, and G. Dennis, ‘ On Recent
Excavations in the Greek Cemeteries of the Cyrenaica’ Trans. R. Soc. Lit.
ser. 2, vol. ix (1870) pp. 141, 156.

590 PROF. J. W. GREGORY ON [Nov. 1971,

(f) Merj to Ptolemeta.

To determine the succession of the rocks in this part of Cyrenaica,
a traverse was made from the plateau-scarp south of Merj to the
coast, near its ancient port, Ptolemais or Ptolemeta.

The relations of the rocks between the plain of Merj and the
Wadi Hamema, through which we descended to the shore, are
uncertain, as, owing to a misadventure, | had to return to Merj
by a night journey. The general section from the plateau south
of Mer] to the sea at Ptolemeta is illustrated by fig. 3 in Pl. XLII.

The coastal plain near Ptolemeta consists of dunes along the shore,
of large delta-fans before the mouths of the wadis, and of wide
sheets of alluvium in the intervening depressions. The delta-fan, by
which the track from Mer] to Ptolemeta reaches the coastal plain,
rises to the height of 340 feet. ‘he rocks above it are chert-
bearing limestones and marls, belonging to the Apollonia Limestone
Series, which continue up to the level of over 940 feet. The rocks
are dipping northwards, in places as much as 25°, the steep dip
being doubtless due to the proximity of the okra Fault, although
there may be parallel faults which I did not detect.

The rocks crossed during the ascent on to the plateau from the
shore (see Pl. XLII, fig. 3) begin above the delta-fan, at the level
of 340 feet, with a dark-grey, compact, dolomitic and siliceous lime-
stone. The rock is succeeded above by a chalky granular limestone
with some black grains, which microscopic examination shows to be
glauconite. This rock, at the height of about 440 feet, includes an
oolitic band, in which Mr. D. P. Macdonald has recognized well-
preserved echinoid spines, nullipores, and foraminifera. A similar
rock occurs in the chalky limestone at Wadi Nagr, west of Derna.

This rock is succeeded by a compact, unfossiliferous, chalky lime-
stone with a rough granular surface. Mr. Macdonald describes it
as containing some calcite crystals and occasional grains of quartz.

Then follows, at the level of from 500 to 550 feet, a series
of compact chalky limestones with some grains of glauconite. Mr.
Macdonald found in the chalky base some Globigerine, sponge-
spicules, and a holothurian plate. The rock includes some layers
of marl and nodules of chert.

At the level of 620 feet the track crosses a small col into the
Wadi Hamema, which has bebeaded the gully followed by the
route to Ptolemeta. At this level and up to over 650 feet, the
rock is a siliceous limestone with abnndant chert-nodules. The
matrix of this rock, according to Mr. Macdonald, consists of a close
calcareous paste with some grains of quartz and glauconite, and
it also contains Globigerina and a holothurian plate. The chert-
bearing rocks are exposed up to the height of 950 feet.

The northern part of this series of beds consists of chalky lime-
stones like those of the Wadi Nagr, and they belong to the upper
portion of the Apollonia Limestone Series. The limestones from
the level of 500 to 600 feet containing the large chert-nodules
represent the lower part of the same series,

Vol. 67.] THE GEOLOGY OF CYRENAICA. 591

The divide between the Wadi Hamema and the plain of Merj,
at the level of about 1100 feet, is formed by some shelly lime-
stones from which Mr. Newton has identified the Miocene Anadara
turonica: whence we may infer that the Apollonia Limestones,
which are exposed in some dry cisterns, are overlain by Miocene
beds. The simplest explanation of the occurrence of these beds in
this position would be that they were deposited unconformably
upon the Apollonia Limestones; but I saw no evidence of their
actual relations.

The cherts are also exposed on the northern slopes of the divide,
between it and the Pleistocene loams of the plain of Merj. Some of
the shelly beds near the pass may belong to the Slonta Limestones,
which are certainly exposed at Merj, as shown by both mollusca
and foraminifera.

The Priabonian or Slonta Limestones occur at the wells of Merj
at the level of only 850 feet, while the Derna Limestone rises in
the face of the plateau 2 miles to the south to the height of
1240 feet. The Slonta Limestones at Mer] must, therefore, have
been lowered either by a fault or by a sharp fold; and the general
evidence is clear that the movement was a fault.

(g) Merj to Benghazi.

The journey from Merj to Benghazi being hurried, there was only
time for a general determination of the rocks close beside the
route. ‘The track crosses the Merj alluvium for 24 miles to the
south-west and then a low ridge of limestone about 6 miles wide,
which separates the plain of Merj from the still larger, but less
regular, plain of Silene. This limestone ridge rises to the height
of about 1130 feet, or about 300 feet above the plain of Merj. The
rock is not well exposed, being covered by a red soil and Thuya-
scrub ; but at 4 miles from Merj there are exposures of a limestone
with large nummulites, which no doubt belongs to the Derna
Limestones, and is continuous with the rocks that bound both
sides of the plain of Merj. I could find no chert, except one or two
artificial flakes which had probably been carried there. From the
summit of this limestone ridge there is a slight fall to the plain of
Silene, over which we marched for 30 miles. Its north-eastern
part is higher than the plain of Merj; but it slopes gradually to
the south-west, and the outlets of its streams are doubtless in that
direction. It is less level than the plain of Merj, consisting rather
of undulating steppes covered with a loamy soil, and passing into
the limestone downs gradually on all sides, except where it meets
the Merj fault-scarp. The surface is wind-swept, and numerous
vertical columns of dust travelled across it. The stream banks
consist of alluvium, which weathers like loess ; they stand up in low
vertical cliffs, and the streams, when they run, are interrupted by
small waterfalls. The chief deposit is a brown loam, interstratified
occasionally with beds of limestone-gravel. A well at Mletania
has been sunk through the alluvium to the depth of 135 feet, and

592 PROF. J. W. GREGORY oN (Nov. rgit,

it is situated only a mile from the border of the plain, there about
6 miles wide. Much of the ground has been cultivated, especially
in depressions where soft loam has been collected as rain-wash.
Near the shrine or marabut of Ahmeda, the loam is covered with
slabs of secondary limestone showing that the alluvium is thinner
there; and blocks of limestone resembling the Derna Limestone
occur on a ridge, which projects from the downs into the western
side of the plain. The surface of this ridge is littered with slabs of
efflorescent limestone.

I could find no exposure of the chert-bearing limestones there ;
but, after crossing the nummulitic limestones for a couple of miles,
we found that ehert-nodules became abundant and then cherty
limestones appeared on the surface. ‘The first specimens of these
cherts were much altered by secondary action, and the cherts were
chalcedonic. At Smuta there is an outcrop of a shelly siliceous
limestone, near the ruins of a Roman fort. The fossils found are,
however, unfortunately indeterminable.

After crossing the watershed between the plain of Silene and the
direct drainage north-westwards to the Mediterranean, we observed
that the country became more irregular, owing to the numerous,
deep, stream-cut ravines. The rock at the edge of the plateau
overlooking the coastal plain contained many casts of shells, but no
determinable fossil was collected. Beneath the shelly limestone
occurred a limestone breccia, including pebbles of black limestone.
A steep gully leads from the plateau to the coastal plain, near the
ruin of an old fort, at the height of about 450 feet above the sea,
and some 16 miles east from Benghazi. The face of the plateau
has been much denuded, but presents the aspect of a fault-scarp.
The rocks at its foot are pinkish and white compact limestones, con-
taining fragments of Scutella and a thick massive Clypeaster. As
the camels had already gone some distance ahead, I was unable to
collect any complete specimens, though the sketches of some of the
fossils indicate that the beds are Miocene, and probably Middle
Miocene. The Scutella Limestone is exposed farther west in
bosses, polished by wind erosion. Nearer Benghazi, these Miocene
limestones are covered by a younger limestone, of which the
characteristic shell has been determined by Mr. Newton as Ceras-
toderma edule (Linn.), and the rock is either late Pliocene or more
probably early Pleistocene in age. The older limestone was still
visible occasionally in depressions in the coastal plain, and in the
solution-cauldrons occupied by the Garden of the Hesperides and
the cave known as the River of Lethe. Nummulites have been
recorded from this limestone by the Archduke Ludwig Salvator,!
and G. B. Stacey called the rock a ‘ Tertiary limestone.’* The
specimens collected there do not contain nummulites, but. a virleti-
form Ostrea, which suggests the Helvetian age of the rock.

1 ‘Yacht-Reise in den Syrten 1873’ Prag, 1874, p. 52.

2 «On the Geology of Benghazi, Barbary’ Q. J. G.8. vol. xxiii (1867) p. 384;
he collected some fossils in the limestone which were not specifically determined,
and found Cardiwm edule on the surface (ibid. p. 386).

. FQ2
Vol. 67. | THE GEOLOGY OF CYRENAICA. O90

Near Benghazi the lower limestones have sunk beneath sea-level,
and the beds exposed around the town are recent dune-limestones
containing common Mediterranean shells, such as Glycymeris
glycymeris (Linn.), Codakia pecten (Lam.), Ostrea edulis (Linn.),
Cheliconus mediterraneus (Hwas), etc. Behind the dune-limestones
and the dunes to the north of the town are wide sheets of alluvium,
which has been deposited in lagoons that are still flooded at intervals
and used as salt-paus.

LY. CLAssIFICATION AND CoRRELATION OF THE CYRENAICAN
Rocks.’ (Continued on p. 598.)

The field evidence, including a preliminary determination of
some Kchinoids, suggested during the traverse of Cyrenaica the
following classification of the rocks :—

Pleistocene. Various alluvial deposits, coastal limestones, etc.
: Scutella Limestones, east of Benghazi, and Gubah-Birlibah
Miacene ...... . =
Limestones.
Cyrene Limestones (Aquitanian).
Lower Slonta Limestones.
Kainozoic. Derna Limestones.

Apollonia (chert-bearing) Limestones.

The most surprising geological result of the journey was the
comparative rarity of Miocene beds. They are so well developed
in Western Egypt, as at Siwa and on the coast near Mersa Tobruk,
that the prevalent opinion in recent years (see p. 576) had been
that Cyrenaica was mainly composed of Miocene rocks. The
subsequent study of the collections has, however, even lessened the
area that in the field I was disposed to assign to the Miocene, as
the species of Arphiope, a genus especially found in that system,
has to be referred back, owing to its associated fossils, to the
Hocene.

The correlation of the rocks of Cyrenaica depends upon the
fossils, mainly mollusca, foraminifera, and echinoids, upon which
reports have been prepared by Mr. R. B. Newton, Mr. F. Chapman,
and myself.

The oldest rocks exposed occur in the Tokra fault-scarp, east
of Benghazi; they are somewhat lower than the chert-bearing
limestones, but no determinable fossils were obtained from them.

1 Owing to the varying nomenclature of the Middle and Lower Eocene
Kainozoic Series, the following synopsis may be convenient for reference :—
Tortonian } 1.
| Helstian } Vindobonian.
Burdigalian or Langhian.
Aquitanian (often included in the Miocene).
Stampian or Rupelian ] Tongrian (sometimes used to
Sannoisian or | ecm include Stampian).
Priabonian or Ludian (sometimes included in the
| Upper. Oligocene).
SA Bartonian.
| Middle. Parisian (Lutetian) ; Mokattam Series of Egypt.
| L eee or Ypresian ; Libyan Series of Egypt.
ower. : : : :
\ Suessonian, Thanetian or Landenian.

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Lists or Fosstxs (contenued).

| Ain Sciahat.
a nn {Tongr. = Tongrian.
Echinoidea. . = ee ees Helv. = Helvetian.
S |e $ - S a g Langh. = Langhian. |
a, |e Ole ola eS
6 |f 2/6 | Ba
m IO jm IA
Clypeaster biarritzensis, var. trot-| U.E. | X
teri nov.
Fibularia luciani (Lor.) ...............| M.E.| ... |... | X | Foot of Cyrene Escarpment.
Scutella tenera Laube ..................|Tongr. x | ... | Labruk ; Bir Hu
Amphiope duffi, sp. NOV...........0.006++. line Sidi Rof Diasiasia.
Amphiope sp. K fase x :
Echinolampas chericherensis Gauth. | U.E. | ... | x | ... | Slonta Limestones near La-
brnk; Safsaf ; Cyrene; below
Ain Sciahat; Cyrene to
Slonta; Messa; Wadi Gharib.
Echinolampas discus Des. ..... Aq. | X ey,
Hypsoclypeus hemisphericus (Gree. y Han ; Birlibah.
Hemiaster scille Wright ............... Aq.to| X
Langh
Schizaster ederi, sp. nov. dippucnscieel| * ae x
| Sarsella lamberti, sp. nov. ............ x
{
Holothuroidea.

Holothuria plates were recognized by Mr. D. P. Macdonald in
the chalky limestone of the Apollonia Series west of Ptolemeta,
and in the Derna Limestones near Merj.

Ostracoda.
Horizon.
He 7 é PURI r
| Lowoconcha en M.E.
| YTCRALCA, SP. DOV. con --.%- de Naar
| Cythere striato-punctata (Rom.) ........ M. ws i Wadi Nagi
| ? Cythere wetherelli Jones ................... U.E. Clypeaster Bed east of
| Ol. Ain Sciahat.
Cirripedia.
| Balanus concavus Brown ....<.... 2.0.06. | Miocene. | Gubah. |
Mollusca.
oT S re S |
gO Bs a
Pleistocene. aad 3 "op 68 |
SES a © oe
== eR o Py
2 Bs eee.
} || _ EE eee
Hygromia sordulenta (Morelet) .. x |
Helicella tuberculata Crees x |
Ostrea edulis Linn. . Ree oy eae x
Glycymeris glycymeris (Lim. Ne ei Ss wer!
Glycymeris pilosa (Liun.) a! mie x
Cardium tuberculatum Linn. ............... 06.60 ee x
Cerastoderma edule (Uinn.) .............<c.c0.000s- x |
Mactra stultorwm Says x
Jagonia pecten (Lam.) .. x
Loripes lacteus (Linn.) .. sci ee Maes see a x |
Cerithium ct. vulgatum Br uguiere . eA ee ota eal x
Columbella rustica (Linn.) . ; Xx |
Cheliconus mediterraneus (Hwasi in n Bruguier e) Xx |

a

s

Mollusca (continued).

2 Ste 3) om .
| Fa so eos
sa he | s Sk =
| Miocene. a Sa 2 ep 3.55 5
= ee | aA | BAe
| oO © AY =
Alectry yonia plicatula (Gel )iaeast cetys ege-oe- x
Alectryonia virleti (Desh. iA eae bs i ast x
Gigantopecten zizinie (Blanckenhor n) .. ree: ict st ee
Anadara turonica (Dujardin) .. BAe ae x
Strombus coronatus (Detrance) x
Sales =
Aquitanian. yell Silica ee | se
Say lio = | 1S S S
fy BID OS) OS | eS
lm Sla2 a mw a
Ola S| AR | OR | SD
lon xq =sef |) (2a) 9) [= |
Ostrea cf. caudata Minster ............... x
Ostrea crassicostata Sowerby . De ie Smee. Pe al We of Lamludeb:
| Spondylus cisalpinus Brongniart eae [eee .
| Pecten vezzanensis Oppenheim age ee aa
Pecten cf. pasini Meneghini ............ | eX Ieee
Aiquipecten zitteli Buches es Lex | lao <ey
Aiquipecten camaretensis (Fontannes) | eats ae
Aiquipecten scabrellus (Lam. ae aN Pe esl
Aiquipecten haueri Michelotti.. ea |
Oopecten rotundatus (Lam.) ............ be! Xa oS, | cee 1X. | Wadi Umzigea:
| |
:|al 3] .S 5 | S
Priabonian. 2 1o:4| 5 |2 ale |
M)S=| 2) 5 a ee
a |F ence Waal les
aia!) SIE alsals
aso! SiS jo. | =
aM |z\2/e/2 |e |
Gee ee Te um Canines. SUB PRIME | SCE Ns |» | Near Bint, E. of Derna.
Pecten arcuatus (Brocchi) .... callis< x |x |x | Near Bint, E. of Derna.
Aquipecten cf. deletus (Michelotti) Derna. |
Aiquipecten cyrenaicus, sp. nov. Above camp at Ain
Sciahat.
Vulsella cf. crispata P. Fischer ...... ne te. |x
| Pailscilee eymari Oppenheim... x
_Spondylus sp. (ef. rouaulti dv Arch.) ee x
Trachycardium cf. granconense | xX |
Oppenheim | | |
LIucina cf. pharaonis Bellardi ........|...) * |X| xX|...| x |... | Pass N.of Wadi Khumas. |
Lucina cf. nokbaensis Oppenheim .. : | Wadi Nagr, first camp
| west of Derna.
Corbis lamellosa (liam.) ............... Pete x eae
Mactra cf. fourtaui Cossmann ......| ... | Pass N.of Wadi Khumas.
Cordita (cf. acuticostata Lam.) ...... Rew " Pass N.of Wadi Khumas.
Euspira possaguensis Oppenheim ...| ... sy East of Ain Hafra.
Ampullina crassatina Lam. ......... eee aes ra Mea erases plevead tlsti
Rostellaria cf. ampla Sol. Rachel tel ck’ reese lie neon ume OF Sidi |
Abdullah; south-east |
Gisortia gigantea (Miinst.) ............! X / of Messa.
Vasum ct. frequens Mayer-Eymar ...| ... x |
Parisian.

Ostrea sp. (ch O. gigantea) ...........000. Near Ain Sciahat.

598 PROF. J. W. GREGORY ON | [Nov. rom,

They probably represent part of the Lower Eocene or Libyan Series
of Egypt. The chert-bearing Apollonia Limestones also yielded
no determinable molluscs or echinoids, but their infraposition to
the Derna Limestone shows that they correspond to the chert-
bearing Upper Libyan Limestones of Egypt: They are succeeded
above by the Derna Limestone, which is shown by its beautifully
preserved foraminifera to be the equivalent of the Lower Mokattam
Limestone in Egypt, and is therefore of Middle Eocene age. The
Slonta Limestones, a stratified series above the Derna Limestone,
according to Mr. Chapman’s identification of the fossils, are also
Middle Kocene. But Mr. Newton reports that the mollusca are
Priabonian, which is regarded either as the uppermost series of the
Kocene or the lowest of the Oligocene.

The evidence of the echinoids agrees with that of the mollusca.
One of the most characteristic beds in the Slonta Series yielded
many specimens of Lchinolampas; but I have been unable to
recognize among them any specimen, either of Kchinolampas cramert
or of &. africanus, the characteristic Upper Mokattam species:
the Echinolampids certainly have Upper rather than Middle Eocene
affinities.

The supposition that the Slonta Limestones may represent the
Upper Mokattam stage is, on the other hand, supported by some
stratigraphical considerations. Thus, at or near the top of the Slonta
Limestones is a widespread horizon containing reef-building corals.
The specimens obtained were casts, and they have not yet been
closely examined ; but the development of the reef-corals at this
horizon must be due to ashallowing of the sea in Cyrenaica, and this
change may have been contemporary with the growth of the reefs
of Orbicella and other corals in the Upper Mokattam Beds of Egypt.

The Upper Mokattam Beds in Egypt are succeeded by fresh-
water and terrestrial deposits, and the only quartz-pebbles found
in Cyrenaica, except along the coast, were obtained at Gasr el
Migdum, in a bed a little above the coral-reef horizon. This pebble-
bed, and the marl containing flattened stem-like fragments that
forms the springs at Cyrene and Messa, may represent a strati-
graphical break corresponding to the Egyptian freshwater beds;
and there is clearly a gap in the succession at or a little above
this horizon, since no representative of the Lower Oligocene (Ton-
erian) was found. The Slonta Beds are succeeded by the Cyrene
Limestone, which is referred to the Upper Oligocene (Aquitanian).

If the reef-coral limestone in Cyrenaica is on the same horizon
as that of Egypt, then the Slonta Beds would be Middle Kocene,
and the gap in the succession in Cyrenaica would include both the
Upper Eocene and the Lower Oligocene.

That the Derna Limestone is Middle Eocene is undoubted. It
is overlain by a hard or rough-weathering limestone, some layers
of which contain so many echinoid-plates and spine-fragments as
to suggest for it the name of the Echinoid Limestone. Some
of the plates came from regular echinoids, but I unfortunately
did not collect sufficient for generic determination. Above
this Echinoid Limestone is a soft white marl containing /vibularia

Vol. 67.] THE GEOLOGY OF CYRENAICA. 599

luciani ; hence this bed and the underlying Echinoid Limestone
may both be included in the Middle Eocene. The /ibularia Bed
is succeeded by a series of limestones which, so far as I saw, were
resting conformably upon it. These limestones include the white
to cream-coloured nummulitic limestone, in which have been
excavated the tombs of the northern necropolis of Cyrene.
Mr. Chapman refers the foraminifera in this rock to the Middle
Eocene. It does not, however, contain the typical LV. gizehensis
foand in the Derna Limestone, but the variety lyelli; and that
variety is also found in the brown-weathering, stratified limestones
at Slonta. There and elsewhere the variety lyell: is associated
with Priabonian, or at least Upper Eocene, mollusca and echinoids.

I am therefore forced to the conclusion that the Slonta Lime-
stone should be included in the Upper Eocene, and regarded as
Priabonian. This view involves the correlation of the hard,
brown-weathering limestones of the Slonta Downs with the soft,
cream-coloured, nummulitic limestone of the northern necropolis
of Cyrene. But, as the two formations both occur between the
Cyrene Limestone and the Derna Limestone, and as they both
contain the same variety of nummulite, they must be approximately
on the same horizon. The difference in their lithological charac-
ters is probably due to the beds at Cyrene having been deposited
farther from land. ‘The occurrence of the variety lyelli may be
due to its survival, owing to favourable bathymetric conditions.

The identification of the Slonta Limestone as Upper Eocene
and Priabonian introduces one important difference between the
stratigraphical succession in Egypt and in Cyrenaica. The coral-
limestones of the two countries must be at different horizons; but
what is more remarkable is that the great gap in the succession
in Cyrenaica would be later than that in Egypt, if the usually
accepted age of the Palwomastodon Beds of Egypt be correct. The
date of that fauna has been the subject of considerable dis-
cussion. According to Dr. Andrews,’ these Palwomastodon Beds
are Bartonian; Prof. Depéret,* on the other hand, from the resem-
blance of Andrews’s Ancodon gorringe: from the Faytiim to the
Brachyodus cluac from the Ebro Valley, holds that the Faytim
Beds are Oligocene, and belong either to the base of the Stampian
or to the top of the Sannoisian. Dr. P. Oppenheim? has since re-
affirmed his acceptance of the Hocene age of the Fayiim beds, and
says that they are at the highest, Ludian, that is, Priahonian.

If Dr. Andrews’s and Dr. Oppenheim’s conclusions be correct,
then the marine deposits ended in Egypt at the close of the Middle
Eocene or Parisian (Lutetian), while the sea still covered Cyrenaica,
which only emerged in the Lower Oligocene. But, if Prof. Depéret
be right, the gap in the marine succession of deposits in Cyrenaica
occurred at the same time as in Egypt.

1 ©, W. Andrews, ‘A Descriptive Catalogue of the Tertiary Vertebrata of
the Fayim, Egypt’ British Museum, 1906, pp. ix, x.

2 Ch. Depéret, ‘Sur Age des Couches & Paléomastodon du Fayoum’ Bull.
Soe. Géol. France, ser. 4, vol. vii (1907) pp. 193-94 ; also zbid. pp. 455-56.

> P. Oppenheim, ‘ Observations sur lAge des Couches 4 Pa/eomastodon du
Fayoum’ Bull. Soc. Géol. France, ser, 4, vol, vii (1907) pp. 358-60.

600 PROF, J. W. GREGORY ON | Nov. 1911,

Some of the evidence of the Cyrenaican fossils is consistent with
Prof. Depéret’s view that the Egyptian mammalian beds are later
than the dates usually accepted: thus Pecten arcuatus, the most
widespread mollusc in the limestones ascribed to the Priabonian,
is also found in the Tongrian; and the Amphiope, found at several
localities, is not an Eocene genus. Its presence led me in the field
to regard the beds containing that genus as, at the earliest, Ton-
erian; but the evidence of the associated nummulites and mollusca,
as also the Upper Eocene aspect of the accompanying Echinolampids,
renders it advisable to regard the presence of Amphiope as due to
an unusually early occurrence of that genus. Otherwise, though
the acceptance of Amphiope and Pecten arcuatus as Tongrian would
approximate to Prof. Depéret’s views, it would increase the difference
between the dates indicated by the foraminifera and by some of
the other fossils.

It may be suggested that the simplest explanation of the conflict
of evidence is that the specimens were mixed after they were
collected. The mixture was however Nature’s, not mine; for
some of the fossils which indicate different dates were cut from the
same hand-specimen.

It therefore seems probable that, because of varying bathymetric
conditions, there was an intermingling of the Middle and even
Lower Eocene foraminifera, Nuwmmulites curvispira and N. gizeh-
ensis, with Upper Eocene mollusca; but, on the reappearance of
N. gizehensis it was represented by var. lyelli, the nummulite
characteristic of the limestones at Slonta and of the soft limestone
excavated into the tombs at Cyrene.

The distribution of the chief nummulites in question is as
follows (with their range in the corresponding horizons in Egypt
and adjacent parts of Asia, quoted from Dr. Blanckenhorn’s
table *) :—

Dr. Blanckenhorn’s Table.
Cyrene Nummulites subramondi and Oper- Lower NV. intermedia and N. biar-
Hels ae) culina libyca. Oligocene. { vitzensis.

Coral-limestone—N. beaumonti.
Limestone of the Cyrene Tombs and
Slonta ; Echinolampas Beds of Slonta—
Limestones. |] NV. gizehensis var. lyellii, N. curvi-
spira, N. subdiscorbina, N. inter-

media, and Operculina libyca.

Fibularia Limestone—NV. cwrvi-

Se genie U N. subdiscorbi
i pper . subdiscorbina and
Echinoid Limestone—NV. subdis- Mokatt se WM hee

corbina and N. gizehensis var.

viquesneli. ;
Derna ea . gizehensis, N. curvispira, N. Lower fa ae a Melee: Ane
Limestones. ( ehrenbergi, and N. rowaulti. Mokattam. iss eee 7, and IV. sub-
Apollonia cake
Teens } N. subdiscorbina. Upper Libyan.

Lower ea libyca, N. biar-
Libyan. ritzensis.

1 ‘Neues zur Geologie & Palaontologie Atgyptens, II. Das Palaogen’
Zeitschr, Deutsch. Geol. Gesellsch, vol. lii (1900) facing p. 406.

Vol. 67.] THE GEOLOGY OF CYRENAICA. 601

The Nummulites and Operculina libyca, which lived from the
Lower Libyan to the Miocene, have therefore a somewhat variable
range in age, and their distribution must be influenced by bathy-
metric conditions.

Above the Priabonian or Upper Eocene rocks of Cyrenaica there
appears to be a gap in the succession, as the next beds recognized
belong to the Upper Oligocene or Aquitanian. ‘The limestones of
Wadi Umzigga and Birlibah contain Lepidocyclina elephantina,
which Mr. Chapman assigns to the Middle or Upper Oligocene
(Stampian or Aquitanian); the mollusca from the same limestone
are identified by Mr. Newton as Aquitanian: hence the rocks may
be accepted as Aquitanian. They are, therefore, of nearly the same
age as the limestones at Cyrene, which are the best representatives
in Cyrenaica of the Aquitanian Series.

At Gubah, west of Wadi Umzigga, the rocks are Miocene, and
probably Helvetian ; and as I found an Echinoid of that age near
Birlibah, there are apparently Miocene outliers on the Lepidocyclina
Limestones.

The Miocene rocks were not once seen resting directly upon the
older rocks. They form the plains at the foot of the Tokra scarp,
east of Benghazi; but there they have been faulted down against
the Lower Eocene beds. Some shelly limestones, from which
Mr. Newton has identified the Miocene Anadara turonica, occur on
the divide between the plain of Mer} and the wadis leading to the
coast near Ptolemeta. They he upon the Apollonia Limestone.
The Gubah Limestones are also probably faulted down against the
rock which forms the plateau near Zawiah Charrah; but we
obtained no definite evidence as to their relations, as we had been
asked to travel quickly and with special care to avoid arousing
suspicion during that stage of the journey.

The sequence of rocks in Cyrenaica is, therefore, more varied
and complex than was anticipated. The Miocene rocks, instead
of occupying the whole country, are sparsely represented, and
Cyrenaica consists essentially of a vast block of
Eocene limestone. ‘This rock is capped by some outhers of
Oligocene and Miocene; while some Miocene limestones have
been faulted against its western foot, and it is fringed by low-
level, marine, Pleistocene limestones.

The suggested classification and correlation of the Cyrenaican
beds and their relations to those of Egypt, Tunis, and Malta, are
shown in the table on p. 602.

The stratigraphical succession in Cyrenaica differs, therefore,
from that in Keypt and Tunisia, owing to the continuity of the
marine rocks in Cyrenaica and their deposition farther from land.
The most striking feature in their lithology is the paucity in
mechanically-derived sediment—a fact brought out clearly by a
careful study of a series of microscopic sections made by Mr. D. P.
Macdonald. The series must include nearly 3000 feet of strata,
which consist of limestones almost entirely composed of organically
formed material. There are occasional beds of limestone-breccia,

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Mol. 67. | THE GEOLOGY OF CYRENAICA. 603

but I only remember finding quartz-pebbles once, and sand-grains in
the limestone are rare. Some of the limestones are argillaceous, or
include layers of marl; and this material is composed of a very fine
clay. We saw no representatives of the terrestrial and freshwater
deposits of Egypt, or of the abundant sandstones and clays found
in the corresponding rocks of Tunisia.

The Cyrenaican limestones must have been deposited mainly in
water of moderate depth. ‘he rocks which indicate the deepest
water are the fine-grained chalky G'lobigerina Limestones, which
form the upper part of the Apollonia Limestones, west of Ptolemeta,
and are also exposed at the Wadi Nagr. During the deposition of
the Slouta Series the sea was shallower near Slonta than at Cyrene,
for clastic material becomes more abundant as the beds are traced
southwards ; hence land doubtless existed in that direction, and
if no considerable river discharged on that coast it need not have
been far away. ‘The widespread coral-reef limestones near the
top of the Slonta Series indicate a shallowing of the sea, aud the
area may have been raised above sea-level during Lower Oligocene
times; tor the Slonta Series of Priabonian age is apparently suc-
ceeded by Aquitanian limestones.

Another gap succeeded the Aquitanian; for the next beds are
shallow-water Middle Miocene limestones, which are widely deve-
loped on the coastal plains east of Benghazi, and are preserved in
occasional fragments on the summit of the Cyrenaican plateau.

The Cyrenaican sequence resembles the Maltese in the persistence
of marine cenditions. The Maltese beds, however, began later,
as the oldest is Tongrian, while the latest is Tortonian. The
Globigerina Limestones of Malta were probably laid down in
deeper sea—Sir John Murray’s estimate for them is 1000 fathoms—
than any in Cyrenaica; but the chalky limestones of the Apollonia
Series were probably formed in water not much shallower. The
long continuity of a variable marine series is a feature
common to the geology of both Malta and Cyrenaica.

V. Tue Trctontc Groroey.

The two essential facts in the structural geology of Cyrenaica
are, that pre-Kainozoic rocks are unknown there’; and that all its
rocks are marine limestones, which, although raised in places to
2500 feet above sea-level, are, except in the vicinity of the main fault,
still horizontal or inclined in broad shallow folds. The country,
therefore, has no resemblance either in composition or in structure
to the Atlas Mountains. It 1s essentially a block of Eocene
Limestone, capped by some outliers of Oligocene and
Miocene, and flanked by Pleistocene. The Eocene rocks,
which form the great mass of the country, resemble those of Egypt ;
but I saw no representative of the Bartonian and Obepecne terres-
trial deposits found in Egypt, as in the Faytim.

1 The most likely position for Cretaceous rocks is on the lower part of the
Tokra scarp.

Q.J.G.8. No. 268. 2T

“ = I St RR NT ER
a ee ee ee ee eee ee 2 —_

—-

604 PROF. J. W. GREGORY ON [ Nov. ror1,

Cyrenaica may, therefore, be described as a plateau formed by a
westward extension of the Hocene limestones of Egypt, and capped
by outliers of the Maltese beds.

The Miocene rocks, which, on the coast of Western Egypt, are but
little above sea-level, occur in Eastern Cyrenaica at the height of
1100 to 1800 feet; and, while the base of the Derna Limestone,

Fig. 4.—Sketch-map illustrating the tectonic relations
of Cyrenarca.

EXPLANATION

=== = Faults.
V = Volcanic.
ca = Cainozoic.
Cretaceous.
Jurassic.
_ Gneiss, schist, | a va B®
Slate, crystalline, + ; Me“ ue
° if
limestone, etc. ? !
4

!
U

I
1
I
y I
li

Mt,
Ts
Lay Es, Tilil
Ww SEUs. pas al oe
Z = Derna

Ptolemeta Saas el Tin
, c & gBomba Bay ipooruk
iM ers? !
Ras el Meth

Bay of
Salum

...a.. Phe dotted linesaround Eubcea L;
are rnajor faults, after Deprat. Ibya

[For ‘Marsa Susa’ read ‘ Mersa Susa.’|

which is correlated with the Lower Mokattam Beds of Egypt, lies
close to the sea-level at Derna, it disappears beneath it farther
east. Westward, on the other hand, the Derna Limestone at Mersa
Susa extends from about 500 to 1100 feet above sea-level, it

1 They are marked on Dr. Ball’s map of Mersa Matruh up to the height of
about 200 feet.

Wol: 67.| THE GEOLOGY OF CYRENAICA. 605

rises in the Wadi Khumas to the height of nearly 1800 feet, and
its base is from 1000 to 1100 feet above sea-level near the plain of
Merj. The main dip is, therefore, from Western Cyrenaica east-
wards into Egypt; hence the Cyrenaican plateau may be regarded as
the western limb of the Egyptian geosyneline, of which the centre
is occupied by the Oligocene basin on the west of the Fayim.

In Cyrenaica, faults are more important than folds.
That some of the main geographical features of the country were
due to faulting was suggested by Spratt.’ He attributed the sharp
bends of the coast, as at Ras el Tin, the Syrtis, and the Bay of Salum,
as also the variations in the level of the plateau, to the influence
of faults. This suggestion was repeated by Dr. Hildebrand’* in 1904.
The general aspect of the country, as seen from the sea, appeared
consistent with this hypothesis, which was confirmed by the facts
discovered during our march.

The faulting happened so long ago that the actual faults are
hidden ; for the scarps have been worn back, and the fault-lines
covered by talus. The existence of the faults was, however, proved
east of Benghazi and near Merj, for in both cases younger rocks
have been lowered against older members of the Cyrenaican sequence.
The Gubah Limestones have probably also been faulted down against
the Eocene limestones.

I expected to find that the step-like descent from Cyrene to the
coast was due to two parallel step-faults, the upper cliff at Cyrene
being the scarp ot one of them. The upper cliff is, however, an
escarpment. The platform at its foot is not a repetition of the
rock (the Cyrene Limestone) of the upper plateau, but an outcrop
of an older, harder limestone, which has resisted denudation. The
lower cliff, however, if we judge from the evidence collected near
Mersa Susa, is doubtless a fault-scarp; for Mr. Newton has identified
the fossils collected on the coastal plain at the foot of the cliff
(for list, see p. 597) as Priabonian in age, and they are lying
at the foot of cliffs of Lower Eocene chert.

The faults of which I obtained definite evidence may be classified
into three main groups, the relations of which are shown in fig. 1
(Pl. XLII) & text-fig. 4 (p. 604).

The first group trends approximately east and west, and forms
the scarps seen from the sea behind Mersa Susa, and near Derna.
In both cases the evidence for the existence of the fault rests on
the identification of the Priabonian limestones at the foot of the
cliffs, and lying against the Lower Eocene rocks. It appears
probable that the coast-line east of Ras al Hilil may be due to the
same fault; and it appears natural to suggest that the long straight
lines of the coast in Marmarica, and of the north and south sides
of Crete, may also have been determined by faults with the same
general trend. (See map, tig. 4.)

The fault east of Derna, which appears to determine the position

1 T. A. B. Spratt, ‘Travels & Researches in Crete’ vol. ii (1865) App. iv,
pp. 375-76.
2 G. Hildebrand, ‘Cyrenaika als Gebiet kinftiger Besiedelung’ 1904, p. 7.
272

606 PROF, J. W. GREGORY ON (Nov. 1911,

of the coast between that port and Ras el Tin, trends about 20° to
the south of east. It thus- approximates toward the direction
of the powerful faults which, as shown by M. Deprat,’ formed the
islands of Eubcea, Andros, and Tinos, and separated Euboa from
the mainland of Greece by the rift-valley of the Talanta and
Kuripo Channels.

The members of the second group of Cyrenaican faults trend
from south-west to north-east. They give rise to the scarps that
bound the plains of Mer} and Silene, as Upper Eocene limestones at
Merj occur at a lower level than the Middle Eocene limestones
of the plateau to the south-east of the town. The Merj fault-
scarp is parallel to the Tokra fault-scarp, down which we descended
on to the coastal plain about 16 miles east of Benghazi. The hills
are formed of Lower Eocene rocks, and that the limestones at
their foot are Miocene is clear from the large Clypeasters and
Scutellas exposed on the wind-swept surfaces. The Tokra fault
must have a downthrow of at least 1500 feet. This fault-scarp
trends towards Ptolemeta, but its precise course is uncertain,
The position accepted for its northern continuation on the map
(fig. 4, p. 604) is based on the Admiralty Charts, Eastern Mediter-
ranean (2158 Bb, corrected to 1907) and Benghazi to Derna (1031,
corrected to 1900); but, according to Camperio,” the fault-scarp
may pass nearer to Tokra, for his map marks the high plateau
as reaching nearly to the shore and ending to the east of Tokra in
a steep descent which trends from about west-south-west to east-
north-east. The Admiralty Charts, however, represent the scarp
as passing farther inland on a fairly straight course, from its
position east of Benghazi to Ptolemeta. The International Geo-
logical Map of Europe (Sheet D VII, 1905) agrees more closely in
this respect with the Admiralty Chart than with Camperio’s map.

The Tokra scarp, as above accepted, is parallel to the Mer} scarp
and is in line with the sharp division in Western Crete between the
Jurassic rocks and the metamorphic area south of Kanea. The
downthrow of the faults would no doubt be on opposite sides in
Crete and Cyrenaica ; but the coincidence of direction is remarkable,
especially as the continuation of this line into Asia Minor separates
the downthrown Kainozoic area of the Smyrna district from the
metamorphic rocks of the highlands to the south-east of Smyrna
and Ak Hissar. This line across Western Crete and from Smyrna
to Ak Hissar is almost at right angles to the direction of the Eu-
beean faults.

The third group of Cyrenaican faults trends approximately north
and south. It includes the Gubah Fault, the continuation of which
may form the headland of Ras al Hilil. The evidence from this
fault supports Spratt’s suggestion that the sharp bends of the coast
on the western sides of Bomba Bay, of the Bay of Salum, and perhaps

1 J. Deprat, ‘Etude Géologique & Pétrographique de l’Ile d'Eubée’
Besancon, 1904.

2 «Carta Heonomica della Tripolitana & Cirenaica,’ published by the
Societa di Esplorazione commerciale in Africa, Milan, 1883.

Vol. 67.] THE GEOLOGY OF CYRENAICA. 607

too of Abu Shaifa Bay and Kanais Bay, are also due to faults. The
abrupt western ending of Crete along a north-and-south line, and
the conspicuous headlands with the same trend, such as Cape
Littinos and the western shore of the Gulf of Morabella, may also
be due to north-and-south faults. (See map, fig. 4, p. 604.)

The throw of some Cyrenaican faults is very great. The fault
behind Mersa Susa had a movement of approximately 1500 feet, and
the Tokra fault had a downthrow to the west of at least the same
amount. The movements, though extensive, are probably of recent
geological date. The best evidence obtained as to their age is from
the Tokra scarp. Limestones with Cerastoderma edule extend over
the coastal plain nearly to the foot of that scarp. I did not see
them along the fault-line, but their, range inland was probably
bounded by it. As the C.-edule Beds are late Pliocene or early
Pleistocene, the fault-scarp was probably formed before the deposi-
tion of these beds; it was certainly later than the Scutella Limestone,
which is probably of Middle or perhaps Upper Miocene age.

The faults are not necessarily of one age, but they were probably
all part of a connected series of movements which apparently began
later than the Helvetian and earlier than the Cerastoderma-edule
Beds. These deposits represent a marine transgression of late
Pliocene and early Pleistocene age, which can be recognized in many
widespread localities on the northern coasts of Africa. If the Tokra
scarp be a continuation of that in Western Crete near Kanea, the
south-west to north-east faults would be earlier than those which
trend east and west and have determined the northern coast of
Cyrenaica ; and the fact that we did not find the Cerastoderma-edule
Beds along the northern coast gives slight support to that hypothesis.
Negative evidence from a hurried examination of so small a propor-
tion of the coast is of little weight, but the fact may be mentioned
in order to direct attention te this point. The Cerastoderma-edule
Beds oceur on the western coasts of Egypt; and, if they are
absent from the northern coast of Cyrenaica, then the faults, by
which the last remnant of the land-connexion between Africa and
Crete foundered beneath the Mediterranean, took place after the
deposition of the early Pleistocene limestones. The land-bridge to
Crete would moreover have been limited in width to the area
between Ptolemeta and Mersa Matruh, where M. Pachundaki has
found the C.-edule Beds.

Cerastoderma edule is widely distributed in Algeria and Tunisia,
and is referred by M. Georges Rolland! to the Upper Pliocene; but,
as its main distribution is post-Sicilian, it is safer to regard the
C.-edule Limestone in Cyrenaica as early Pleistocene, the age
accepted for it by Dr. Blanckenhorn * and by M. Pachundaki.’

1 «Géologie du Sahara Algérien & Apercu géologique sur le Sahara, de l’Océan
Atlantique 4 la Mer Rouge.’ Chemin de Fer Transsaharien (French Government
Report), Paris, 1890, pp. 194-95.

2 «Neues zur Geologie & Palaontologie Agyptens—IV. Das Pliocan- &
Quartarzeitalter’ Zeitschy. Deutsch. Geol. Geselisch. vol. liii (19V1) table
facing p. 308. ;

> *Contribution a VEtude Géclogique des Environs de Marsa Matrouh
(Marmarique)’ Revue Internationale d’Egypte, vol. iv (1907) pp. 4 & 6.

608 PROF. J, W. GREGORY ON [Nov. 1911,

Though important earth-movements in this area have apparently
happened as late as the Pleistocene, they appear to have ceased
before historic or even Paleolithic times. ‘The sea-level cannot have
been notably altered at Derna since the date of the Paleolithic
camp at Bonmansur. I saw no recent raised beaches along the
coast ; and there are no distinct signs of recent subsidence. Stacey
has referred to modern subsidences at Benghazi, while F. W. &
H. W. Beechey have referred to indications of the recent advance
of the sea seen during their surveys of the ancient Greek ports of
Tokra, Ptolemeta, and Mersa Susa. The evidence even at these
localities seems, however, to show that there has been no marked
displacement of the shore-line since classical times. The sea has
no doubt encroached at Benghazi and Mersa Susa,’ but its advance
at both places may be explained by ordinary coastal abrasion, with
subsidences due to solution of limestone. The Glycimeris Limest ones
at Benghazi and Ptolemeta would suggest a slight emergence of the
land, and not a subsidence ; but they may have been storm-beaches
and dunes subsequently separated from the sea by silting.”

The ancient whart at Ptolemeta, according to the Beecheys’ map,
is now 150 yards from the shore-line, but the intervening beach is
probably due to silting. At Mersa Susa there has been a slight
encroachment of the sea near the ancient theatre; it has, on the
other hand, receded at the old harbour, probably through silting,
for the ruins of the ancient piers appear to stand at exactly their
original level. The maps of Mersa Susa, Tokra and Ptolemeta,
revised from the Admiralty Chart by Smith & Porcher,* show that
there has been no serious change of sea-level since the building
of those ancient towns by the Greek colonists, who began the
colonization of Cyrenaica about 620 B.c.

VI. Tue Wants, anp PossIBLE VARIATIONS IN
PLEISTOCENE CLIMATE.

The preceding evidence shows that Cyrenaica is a block of Eocene,
Oligocene, and Miocene limestones, which was uplifted in Upper
Miocene times (if the Gubah Limestones be Helvetian) and sub-
sequently isolated by the foundering of the surrounding areas. The
first subsidences in the Lower or Middle Pliocene formed the Tokra
scarp and the Gulf of Syrtis, for the Cretaceous rocks—as at Tripoli
—are separated from the sea only by Pleistocene deposits. The

1 The most definite evidence of the advance of the sea is at Benghazi.
G. B. Stacey writing in 1867 quoted Arab testimony that horse races had been
held 50 years previously, inside the reef where the water was now 5 feet deep ;
and he states that the ruins of buildings were to be seen at low water on the
reef: Q. J.G. 8S. vol. xxiii (1867) p. 884. The present brackishness of the
wells at Mersa Susa has been regarded as evidence of encroachment of the
sea or subsidence of the land by George Dennis, ‘On Recent Excavations
in the Greek Cemeteries of the Cyrenaica’ Trans. R. Soc. Lit. ser. 2, vol. ix
(1870) p. 144.

2 That the shore has receded at Benghazi is remarked by F. B. Goddard,
‘Researches in the Cyrenaica ° Amer. Journ. Philology, vol. v, No. 17 (1884)

yO

3 ‘History of the Recent Discoveries at Cyrene’ 1864, pl. i.

Vol, 67. | THE GEOLOGY OF CYRENAICA. 609

great tract of lowland, extending from Egypt to the south of
Cyrenaica through the Oases of Siwa and Aujila, may have sunk at
the same time, or it may not have been raised by the Miocene up-
lift to the same extent as Cyrenaica.

The maps of Cyrenaica, as for example that in Dr. Hildebrand’s
‘Cyrenaika’ pl. ili, represent the country as descending to the
south in two steep steps; one of these steps is situated 25 miles
south of Slonta; the other is much farther south, and it separates
the Libyan Plateau from the lowland of the Wadi Fareg and the
Oases of Siwa and Aujila, of which the former certainly and the
latter probably are below sea-level. This representation suggests
that the southern boundary of Cyrenaica consists of one or
two faults, of which at least the southern is connected with the
foundering of the Siwa-Aujila depression. The Slonta Arabs, how-
ever, assured us that the country passes gradually downwards into
the Aujila plain; and if so, the Aujila district probably did not
share the Miocene uplift, which increased gradually northwards.’

The predominant dip of the beds in Northern Cyrenaica is north-
ward, and this direction continues as far south and west. as the Wadi
Khumas and Messa. In Central and Southern Cyrenaica the pre-
dominant dip is southward, and it is probably the same in South-
eastern Cyrenaica. The main dip-slope, due to the Upper Miocene
movements, was therefore to the south. The consequent rivers
would, therefore, have carried whatever drainage there may have
been down the southern slopes of Cyrenaica through the Wadi el
Bah westwards to Benghazi, and through the Wadiel Ajara el Remla
eastwards to the Bay of Bomba. Along the line of our traverse the
most conspicuous drainage is to the north, although at Slonta and
Silene we crossed streams beginning with a southward course. and
the northern margin of the plateau has been notched by numerous
gullies cut by obsequent streams. The wadis in Northern Cyrenaica
are now deep cafions forming the most picturesque features in the
scenery. Although some of the limestones, such as the typical rock
of the Derna Limestone, are very soft, the cliffs of the wadis are
sometimes vertical. These cafions, such as the wadi west of Mersa
Susa (named by Smith & Porcher the Wadi Lebaiath, but my guide
called it the Wadi Dimi-ell), the Wadi Jebrail, and the great
Wadi Derna, are so large that they inevitably suggest the question,
whether they were not excavated by great perennial rivers, when
the country had a better water-supply and heavier rainfall than
at present.”

1 The evidence of the Arabs (see p. 586) agrees with the conclusion in ©
Dr. Hildebrand’s text, op. cit. pp. 151-152: ‘We do not yet. know how the
whole Libyan plateau rises towards the north, whether it rises in terraces,
whether it slopes up gently, or whether our Cyrenaica is placed on it like a
dome. Only one thing almost all travellers have united in stating, that
Cyrenaica gradually sinks to the south and at last loses itself in the Libyan
Desert.’

2 Corresponding to Dr. Blanckenhorn’s ‘ Pluvial Period’ in Egypt, ‘ Neues
zur Geologie & Palaontologie Adgyptens—IV. Das Pliocan- & Quartar-
zeitalter’ Zeitschr. Deutsch. Geol. Gesellsch. vol. liti (1901) p. 393 & table
facing p. 308.

610 PROF, J. W. GREGORY ON [Nov toms

The occurrence of boulders 3 feet in diameter embedded in an old
sheet of silt at the mouth of the Wadi Nagr, and of others lying on
the bed of the wadi west of the Wadi Susa, shows that the floods
have been of great power. Nevertheless, there does not seem to
me any adequate evidence of a greater rainfall in Cyrenaica in
historic times.’ Northern Africa no doubt had a better rainfall than
at present, at the time of the glaciation of parts of North-Western
Kurope: for the cyclonic systems, which now traverse Europe from
west to east, would then have followed a more southern path. But
that meteorological factor appears to have benefited Algeria and
the Atlas Mountains rather than Cyrenaica, for even the older
parts of the deep Cyrenaican wadis present the characteristics of
canons cut inan aridcountry. Nevertheless, it is probable that the
wadis were cut at a time of heavier rainfall than at present, for very
little excavation is now taking placein them. In some of the valleys,
such as the Wadi Khumas north of Slonta, various facts show that
there cannot have been any flow of water down the ravine for some
years past. Thus plants ofseveral years’ growth stand on the lowest
part of the channel; traces of cultivation, which must. have been
several seasons old, remain undisturbed on sheets of clay in depres-
sions of the river-bed; footpaths have been worn clear of pebbles ;
and slight ridges of earth have gradually accumulated across the
dry river-bed. Just above the lowest part of Wadi Khumas the
valley contracts to a narrow gorge, which is filled with trees
and shrubs, and I could see no flood-marks upon them. There can
have been no heavy flood through this outlet for at least several
decades. Below this point, however, a large tributary comes in
from the north, from the neighbourhood of Messa; and the traces
of recent movement of coarse gravel and the absence of shrubs from
the river-bed, show that water had flowed across that river-bed
within the last year or two. In the Wadi Jeraib some patches of
rolled shingle with only young vegetation give evidence of some flow
in a recent season ; but the amount cannot have been considerable,
for lower down the wadi the evidence of the flow had disappeared.

There is no evidence of any considerable deepening of these wadis
in recent years. The largest cedars that we saw in Cyrenaica were
in the Wadi Jeraib, where they are growing almost level with the
river-bed, and chariot-tracks in the lowest part of the same wadi
show that the bed has not been appreciably lowered since Roman
times. Chariot-tracks worn in the limestone in other localities also
show that the wadis have not been materially deepened since the
Roman occupation. The gravel-platform at Bonmansur in the
Wadi Derna may have been partly worn away since its occupation
by Paleolithic man; but even there it is quite possible that no
appreciable change has taken place since his time.

1 The conditions of existing rainfall and water-supply are stated in the
Expedition Report, pp. 5-6, 9-10, and in the Report by Mr. M. B. Duff,
p- 38-44. The most reliable rainfall records available, those at Benghazi
from 1891 to 1894, are included in the table opposite p. 46.

Mol: "67. THE GEOLOGY OF CYRENAICA. 611

There does not seem to be the slightest physiographic evidence of
any considerable change in the rainfall or water-supply of Cyrenaica
since the days of the Greek colonization inthe seventh century B.c. ;
and the evidence furnished by the classical descriptions of the
country, as also the waterworks erected by the Romans, indicates
that the country was then under the same climatic conditions as
at present.

J. P. Thrige, in his ‘ Res Cyrenensium’ 1819 (2nd ed. 1828), has
collected the classical records respecting Cyrenaica, and they indicate
that the climate of the country was much the same in ancient as in
modern times. There were probably more trees under the Romans,
as they were then more carefully preserved ; but the characteristic
products of the province, such as wool, honey, wax, and corn, are
indicative rather of moorlands with a limestone soil, than of a
humid, wooded country. Plagues of locusts, insects characteristic
of arid plains, devastated the land then as they do now: thus,
in the year 125 B.c. they came in such swarms that accumulations
of their bodies along the shore are said to have caused a pestilence.
Other visitations are recorded, and they were so constant a danger
that a law, quoted by Thrige (paragraph 80),

‘made it obligatory for the people to wage an annual war against locusts,
destroying first the eggs, then the brood, and ultimately those that had
grown up, and imposed a penalty for negligence.’

The waterworks, which are the most conspicuous remains of the
Roman occupation, also show that the country suffered from a scanty
water-supply. Water was stored with great care, and Cyrene received
a supplement of water from some artificial roofed reservoirs at
Safsaf, about 6 miles distant in a straight line. The capacity of
these reservoirs was measured by Dr. Trotter; the largest is about
960 feet long, 16 feet wide, and 14 feet deep; and the whole of
them would have held about 1,500,000 gallons. If Cyrene had
had a population of 15,000, the Safsaf reservoirs would have
provided an allowance of only a gallon per head per day for three
months. It would not have been worth while building a long
stone aqueduct to carry sosmalla quantity, if a considerable supply
had been available at Cyrene.’

Again, ancient Ptolemeta, according to Beechey,” had no springs,
and was dependent for water upon an aqueduct: whereas, if there
had heen a reliable rainfall, wells in the ground behind the town
would have yielded a considerable supply.

The ruins of ancient Greek and Roman buildings near all the

1 It may be suggested that at the date of the first Greek colony the country
had a wetter climate than at present, and that the Roman water-supply works
mark the effort of the later colonists to maintain their hold over the country
despite the increasing desiccation; but I can find no support for this
suggestion, either in the classical literature, or in the physiography of the
country.

2 F. W. & H. W. Beechey, ‘ Proceedings of the Expedition to explore the
Northern Coast of Africa, from Tripoly eastward’ 1828, p. 361. See also
R.M. Smith & E. A. Porcher,‘ History of ... Discoveries at Cyrene’ 1864, p. 66.

.

a _ ais =o

612 THE GEOLOGY OF CYRENAICA. [Nov. 1911.

chief existing springs show that 2000 years ago those localities
were the most important centres in the country, and that con-
siderable springs were no more numerous than they are now. We
saw no evidence that the springs had much larger volumes in
classical times ; and that the springs at Cyrene are as abundant as
ever is asserted by the ‘ Mediterranean Pilot’ (4th edit., vol. 11,
1905, p. 325). The country, moreover, in classical times suffered
from famines following drought, as still happens occasionally, as
just before the visit of Bruce to Benghazi in 1766.’

That the region to the south of Cyrenaica was arid in classical
times is shown by the fact that Cyrenaica was the starting-point of
caravan-routes to the Oases of Aujila and of Siwa, through which
then, as now, passed one of the chief caravan-routes from Cyrenaica
into Egypt. That these routes traversed a desert country is evident
from the statement of Strabo,” according to whom, behind Cyrenaica
and the Syrtis, is a very sterile and dry tract in the possession of the
Libyans ; and Aujila and Ammon (that is, Siwa) were then oases
well supplied with water and productive of palm-trees. How little
the geography of Cyrenaica has altered since the time of Strabo is
shown by his statement that the country behind the coast produces
trees for the width of 100 stadia,* and then for another 100 stadia
the land is only sown, but from excessive heat does not grow rice.
Hence, the tree-belt in Cyrenaica was then about 114 miles wide,
and to the south of it was a belt, also 114 miles wide, of treeless
plains producing dry cereals. The forests may have been thicker
in classical times than they are now, but the forest-belt was ap-
parently no wider.

That Cyrenaica in pre-classical times had a heavier rainfall
seems to me probable from the aspect of some of the old valleys,
which, from their curves and shape, I should suspect to have been
carved during a period of greater rainfall; but this period, though
doubtless Pleistocene, was probably pre-classical, and even earlier
than the time of the people who made the stone implements which
are scattered abundantly in several districts of Cyrenaica.

VII. THE Composition OF THE SOILS.

A series of analyses of the soil of Cyrenaica by Dr. J. Trotter is
tabulated in the Report of the Expedition (pp. 28-36). As that
report may not be easily accessible, some of the analyses are
here reprinted. Nos. I-JII illustrate the sedentary soils; nos.
IV—-XI the transported soils.

1 R. L. Playfair, ‘Travels in the Footsteps of Bruce in Algeria & Tunis’
1877, p. 285.

2 The Geography of Strabo’ translated by H. C. Hamilton & W. Falconer,
vol. 111 (1857) p. 294.

3 The stadium, according to Smith’s ‘Dictionary cf Greek & Roman
Antiquities’ (1845, p. 344) is 606 feet 9 inches English. 100 stadia = there-
fore about 114 miles.

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614 PROF. J. W. GREGORY ON {| Nov. tomEe

VIII. Summary or Concrvstons.

Cyrenaica is a plateau of Eocene limestones ranging from the
Lower to the Upper Eocene, and capped by limestones referred to
the Aquitanian and the Miocene. ‘The predominant dip is to the
east, so that the Miocene limestones found on the plateau in
Eastern Cyrenaica occur close to sea-level on the western coasts
of Egypt. The Cyrenaican plateau may, therefore, be regarded as
part of the western limb of the great syncline of Western Egypt.

The plateau has been isolated and fractured by a series of faults
of late Kainozoic date. The position of the northern coast of Cyre-
naica is determined by these faults, and the Tokra scarp separates
the main plateau from the coastal plain east of Benghazi. The
Tokra Fault is on the same line as an apparent fault in Western
Crete.

The faults may be divided into three groups :—(1) those ranging
east and west along the northern coast; (2) those trending from
south-west to north-east, including the Tokra scarp and the
parallel scarp which bounds the plain of Mer}; and (3) the north-
and-south faults which have determined some of the chief bends in
the northern coast of Cyrenaica and Western Egypt. The three
series are connected with the faults which have broken up the land
of Agea and formed the rift-valleys that have separated Eubcea
from the mainland of Greece.

The rocks of Cyrenaica are limestones composed almost entirely
of organic material. They contain occasional quartz-grains and
some very fine clay. The limestones have been deposited in a clear
sea, and usually in moderately deep water, though at the top of the
Slonta Limestones there is a bank of coral-reef limestone. The
limestones range from shallow-water deposits, down to those formed
at a depth approaching 1000 fathoms.

The rocks may be classified as follows :—

PAeUs GOCE Meo. sxc ie0 sls Alluvial deposits, etc.
MSO COMO Ls oy snclh9.c8hen nen Gubah Limestones.
Olio Ceme eos. Cyrene Limestones.

Derna Limestones.

Slonta Limestones.
Apollonia Limestones.

L

The geological history of the country begins with the deposition
of the chert-bearing Apollonia Limestones, which may be cor-
related with the Libyan or Lower Eocene Series of Egypt. The
sea probably deepened to nearly 1000 fathoms, at which depth
were deposited some chalky limestones with Globsgerina. A re-
elevation of the sea-bed led to the formation of limestone-breccias
and conglomerates. Then followed another subsidence, during
which were formed the cream-coloured limestones of Derna. This
horizon is characterized by the typical form of Nummulites gizehensis.

ya
fe

*

ec cd

wae

Fig. 1.

Geological Map

OF
CYRENAICA
by J. W.Gregory,D.Se.,L.R.S.

Ptolemeta,

Main Faults.

Alluvium, Dunes,
Dune Limestones, etc.

Gubah Limestones.
Oopecten Limestones.

Cyrene Limestones.

Slonta Limestones.
Fibularia

Derna Limestones.

Scale of Miles
10 20

SSS Apollonia Limestones.
Limestones below
1

the Chert Beds.

& Echinoid Limestones,

Pleistocene.

Miocene.
Aquitanian.
Priabonian.

Middle Eocene.

: Lower Eocene.

Ras el Hilil

Fig. 2.—Section from Benghazi to Derna: distance = about 170 miles.

Quart. Journ. Geol. Suc. Vol LXVII, Pl. XLII.

S— L)las el Tin

Bomba Bay

Probable
enlension
RS Tiocene
oy Mersa

Tobduk

Benghazi Coastal Plain — Smuta Ash im Well, Plain of Merj Plain of Plain of Wadi
W. east of Benghazi Meda Mietania Silene Merj Bigratah Gharib
> Peet Caves of River Lethe *
2000
1500

1000

500

Shancthvvelll lke?

Shrineof Wadi Gasrel Wadi Messa Cyrene Labrak Lamludah Zowiah Gubah Barock Mugdock Birilibah Derna Bint
Abdullah Argub Migdum Jeraib Charrah Wadi
| Umzigga E
4 5 BA 6 4 | 8s Feet

1 = Sand-dunes, dune limestones, alluvium, ete.
Y= Cerastoderma-edule limestone,

3 = Limeatones of the Benghazi coast-plain and Gubah (Miocene, prebably Helvetian).
4 = Cyrene Limestones (Aquitanian).

} Pleistocene.

8 = Derna
9 = Apollonia Limestones.

Limestones.

10 = Pre-Apollonia Limestones, } HOWE? Bocer Libyan:

Mery

Ss Merj Plain of
Fault Scarp Merj
Feet
2000

Slonla Limestones

Alluvium

Limestonese=

[1=Limestone with chert-nodules; 2=Cherty, hard limestones;
4=Chalky Globizerina limestone: 5= Oolitic limestone:

3=Cream-coloured limestone, with thi

,
Ii00

i

: . - Cer | 7 . males
Fig. 3.—Section from the Merj fault-scurp to the sea near Piolemncia : distance = about 12 miles.

,

940

Sea-level

— Coral-teef limestones, near the top of the Slonta Limestones. | Priabonian,
_ 6 =Slonta/Limestones.
7 = Eehinoid Limestones. | \¢;q-Wocene—Mokattam.

W. of N.
Ptolemeta

6= Compact limestone.)

Apollonia Limestones
probably
repeated by faut Its.

500

Sea-level

Vol. 67.] THE GEOLOGY OF CYRENAICA. 615

The Derna Limestone was succeeded by a marly limestone containing
Fibularia luciani, followed by the deposition of a rough-weathering
massive limestone containing many echinoid fragments. This rock
was succeeded by the deposition of the stratified Slonta Limestones,
which are represented near Cyrene by a soft cream-coloured num-
mulitic limestone containing WV. gizchensis, var. lyelli. This rock
appears to pass southwards into the harder brown-weathering
Slonta Limestones, which were formed in shallower water. The
Slonta Limestones contain Priabonian molluseca and an Echino-
lampas Bed, in which the common species is referred to E. cheriche-
rensis Gauth., of the Priabonian of Tunis. The deposition of the
Slonta Limestones was brought to an end by a stratigraphical
break, and the next series begins with a glauconitic marl containing
many rolled limestone-fragments. This bed passes upwards into
the yellow Cyrene Limestone, characterized by the abundance of
Operculina. That limestone is referred, from the evidence of the
molluscs and echinoids, to the Aquitanian. These beds are best
developed above the Fountain of Apollo at Ain Sciahat, Cyrene.

Miocene rocks occur at Gubah, where they have been let down by
faults, and along the coastal plain east of Benghazi, where they lie
at the foot of the Tokra scarp. The country appears to have been
uplifted after the Middle Miocene, and to have become part of a
wide land which extended northwards and included Crete and the
Aigean Sea.

The land was afterwards broken up by great subsidences, which
left Cyrenaica as a horst, bounded by the fault-scarps on the
north and west, isolated from Crete, and sinking slowly southwards
to the Siwa-Aujila depression.

The river-valleys in Northern Cyrenaica belong to an obsequent
system, the formation of which was probably started during a
period when the rainfall was heavier than at present; but there
appears to be no evidence of any appreciable change in the climate
or water-supply of the country since the date of the Greek coloniza-
tion, which began about 620 B.c.

EXPLANATION OF PLATE XLII.

Fig. 1. Geological map of Cyrenaica, on the scale of 20 miles tothe inch, or
1 : 1,267,200.
2. Section from Benghazi to Derna.
3. Section from the Merj fault-scarp to the sea near Ptolemeta.

616 MR. R. B. NEWTON ON [Nov. 1911,

(B) Karnozorc Motxiusea from Cyrenatca.
By Ricnarp Buiien Newroy, F.G.S.

[Puatzs XLITI-XLVI.]

ConTENTS. P

age

TL. Min Groce on’ s26255c05, Wake. os cheece eee eee 616
TE SP Ostee @cene. 65) es. eas ane bere cas Seetica nose seers 619
TEE. Helwetian-Tortonian. ...ac.cnocscs-ackoe cancer 625
PVE PAGUATAMNIEAN ccssne shite cate — dole ap nantise ceacs 9 PERE 628
Vie pera DOMIAN 03 casomedse mene cis teen eee 636
Wel SD eLI AN cow thinaicoohakeanassesaceee nee eon uae eee 649
Wil chvesulés: fc ecs8cehecs: Uc jase nine eeaseeee aan 650

I, IntRopvucrion.

Amone the geological specimens obtained from Cyrenaica by Prof.
J. W. Gregory, during a journey through that province of Northern
Africa in the summer of 1908, are a considerable number of molluscan
remains, which it has been my privilege to study and report upon
in the following notes. Itmay beat once mentioned that the more
important part of this collection will be presented by Prof. Gregory
to the Geological Department of the British Museum (Natural
History).

Speaking generally, the shells are badly preserved, and some
consist merely of internal casts; hence only one new species has
been made, namely, Agucpecten cyrenarcus, referred to the Pria-
bonian horizon—a more useful purpose, it is hoped, being served
in the endeavour to show relationships to already described forms.

The specimens are, however, easily divisible into various groups
of the Kainozoic System, none offering characters that would in-
dicate their attribution to the Mesozoic or any older series of the
sedimentary rocks.

The more ancient specimens are the most numerous and
probably of greatest importance, since they denote such horizons
as the Lutetian, Priabonian, Aquitanian, and Vindobonian: those
of later age belonging both to the earlier and to the newer deposits
of the post-Pliocene Epoch.

The rocks associated with the Lutetian and Priabonian fossils are
full of nummulites and occasional specimens of Orthophragmina ;
while those that form the matrix of the Aquitanian and Vindo-
bonian specimens exhibit foraminiferal organisms such as Oper-
cutina, Amphistegina, Lepidocyclina, etc., but no nummulites. This
is interesting confirmation of what has been generally recognized,
that nummulites ceased to exist when the Aquitanian Period
had arrived, their place being taken by Lepidocycline forms of
Orbitoides.*

So far as the literature of this subject is concerned, very little is

1 A. de Lapparent, ‘ Traité de Géologie’ 5th ed. (1906) p. 1586]

—

Vol. 67. ] KAINOZOIC MOLLUSCA FROM CYRENAICA. 617

known of the paleontology of Cyrenaica, although the few references
available suffice in a general way to indicate the geological relations
existing between that country and contiguous regions of Northern
Africa, Crete, and other portions of the Mediterranean area.

Some of the earliest remarks on this subject were made by
Admiral T. A. B. Spratt, in his‘ Travels & Researches in Crete’
1865 (vol. ii, p. 378), where he incidentally described the geological

structure of Derna (Derneh) in Cyrenaica, reporting the occurrence
of freshwater deposits, and of an older group of strata, more ancient
than those of Malta, containing nummulitic tests such as are found
in Crete. It was further mentioned, in the same work, that at
Salum, to the east of Cyrenaica, ‘ Vautilus zigzaggia’ had been
found—a form which he believed to be restricted to the London
Clay, the Paris Basin, and the Maltese beds ; yellowish limestones
were also stated to occur above the nummulitic rocks at Derna,
full of pectens, echinoids, etc. This account of the structure of
Derna was embodied in the following section :—

1, Freshwater deposits (lacustrine—Limnea).
2. Yellowish limestone ( Pecten, etc.).
3. Nummulitic beds.

Two years later, G. B. Stacey, in his paper ‘ On the Geology
of Benghazi,’ ’ referred to fossils trom that area as—three species of
Echinodermata, two forms of Ostrea, a Pecten, two corals, ‘ a worm
in the form of a Helix’; and on the surface Cardium edule. No
particular age was assigned to any of these organisms, although it
was recognized that the fundamental rock of the country was a
Tertiary limestone.

The Archduke Ludwig Salvator, describing the Cave of Lethe,
east of Benghazi, observed that its walls were formed of ‘ Num-
mulitenkalk.’ *

An interesting specimen of Nwmmultes, now in the British
Museum and formerly collected by Admiral Spratt, was referred to
by the late Prof. T. Rupert Jones, in his ‘ Catalogue of Fossil
Foraminifera in the British Museum (Natural History)’ 1882,
p- 45, as Nummulites perforata from Mersa Susa (an ancient
port of Cyrene), and he remarked that it had oS obtained ‘ from
strata younger than the nummulitic bed of Crete.’

Zittel, in the introduction to his great work on the Geology of
the Liby an Desert, stated that

‘In the neighbourhood of Siwah the coarse Miocene limestone is the latest

marine sediment of the Libyan Desert. Probably it extends northwards over
the Cyrenaican tableland.’ (Paleontographica, vol. xxx (1883) p. exxxi.)

1 Q. J. G. S. vol. xxiii (1867) pp. 384-86.

* «Yacht-Reise in den Syrten, 1872’ Prague, 1874, p. 52.

3 This Cretan deposit is regarded at the present day as of Lutetian or
Middle Eocene age ; see A. de Lapparent, ‘ Traité de Géologie’ 5th ed. (1906)
p. 1530.

618 MR. R. B.. NEWION ON [ Nov. 29mm

Two years later, Prof. Suess,’ on the strength of Zittel’s state-
ment, regarded the Miocene ‘Grobkalk’ of Western Egypt as
belonging to the second Mediterranean Stage, and hence as of
Vindobonian or Helvetian-Tortonian age.

In 1884 Dr. Schweinfurth * collected fossils at Mersa Tobruk
(Marmarica), which he regarded as of Miocene age, including
Scutella. Subsequently M. G. Rolland® briefly referred to the
Miocene (‘ Molasse Marine’) rocks in the neighbourhood of the
Siwa Oasis of Egypt and their extension to the plateau of
Cyrenaica. Such deposits, he stated, were, according to Fuchs,
representative of an age between the first and second Mediter-
ranean Stage, or the ‘Sables de Grund’ of the Vienna Hasin
(=Lower Helvetian or Uppermost Burdigalian).

Some years later, Schweinfurth’s fossils from Mersa Tobruk,
and others obtained in 1890 from Mersa Badia, were systematically
examined by Dr. M. Blanckenhorn, and included as part of the
Miocene fauna in his memoir, ‘ Neues zur Geologie & Paladontologie
Afgyptens: I1]—Das Miociin.’ *

Dr. G. Hildebrand, in his work ‘ Cyrenarka als Gebiet kunftiger
Besiedelung ’ (Bonn, 1904) pp. 84-86, recognized Miocene rocks
only in that country, and doubted the presence of Nummulitic
deposits. Describing some rocks from Tripoli, Prof. Stanislas
Meunier? mentioned that he had seen none from that country
older than Lutetian : specimens supposedly of Cardiwm were tound
with analogies to those of the Calcaire Grossier of the Paris Basin,
but another Cardiwm occurring in the Tertiary rocks of Cyrenaica
was more recent than those from Tripoli.

Writing on the geology of Tripoli, Dr. L. Pervinquiére ° noted
the occurrence of Cretaceous fossils in that country, as previously
determined by Beyrich‘; and a year later Dr. Lothar Krumbeck
published figures and descriptions of Cretaceous fossils from the
same country. A brief general notice of the geology of Cyrenaica
is given by Prof. J. W. Gregory’ in an official account of his
journey to that province, in which he rejects the inferences founded
on statements by Della Cella concerning the discovery of ammonites
in 1817, which suggested the presence of Mesozoic rocks in that
area of Northern Africa.

' «Das Antlitz der Erde’ vol. 1 (1885) p. 470.

2 Bull. Inst. Egyptien, ser. 2, No. 4 (1884) p. 82.

° *Géologie du Sahara Algérien, ete.—Chemin de Fer Transsaharien ’
French Government Report [Paris] 1890, p. 86.

* Zeitschr. Deutsch. Geol. Gesellsch. vol. liii (1901) pp. 104 & 105.

° Bull. Soc. Géol. France, ser. 4, vol. v (1905) p. 69.

° Ibid. pp. 527-29.

* Monatsh. Verhandl. Ges. Erdkund. Berlin, vol. ix (1852) pp. 156-62.

8 Palzontographica, vol. lili (19U6) pp. 51-135, pls. vii—ix.

9 «Report on Work of Commission, Jewish Territorial Organization’ 1909,
p. 0.

al. 67. | KAINOZOIC MOLLUSCA FROM CYRENAICA. 619

II. Post-Piiocent.

The post-Pliocene mollusca are both marine and non-marine.
Among the marine, which are the most numerous, are those found in
marls and compact limestones obtained from west of Ptolemeta and
the plain east of Benghazi, and considered to belong to an ancient
series of the post-Pliocene Period. On the other hand, there is
a series of shell-remains contained in a cream-coloured limestone
made up of comminuted shells and minutely-formed calcareous
pebbles, loosely, though closely, agglutinated together, occurring at
Benghazi, which is apparently a recent beach-deposit and much
younger than those limestones described as belonging to the older
beds of this period. In this youngest series of deposits would be
also included a few terrestrial shells, forming part of this collection,
obtained from the plain east of Derna, and Bonmansur, south of
Derna. ‘The whole of the marine shells have been referred to
Mediterranean or Atlantic species, the terrestrial representing forms
now living in Mediterranean countries and chiefly those of Northern
Africa.

The oldest post-Pliocene shells include chiefly Cerastoderma edule,
which occurs in abundance to the east of Benghazi. Similar shells
are known over the whole of Northern Africa and Mediterranean
countries generally, and, when occurring 1n rocks fairly well removed
from the sea-border, are recognized as belonging to the more ancient
series of this period. M. Rolland has furnished a good account of
the occurrence of this shell in Algerian localities.!

The non-Marine post-Pliocene (Recent Beds) Mollusca.

Gastropoda.

Hyeromia sorputenta (Morelet). (Pl. XLIII, figs. 1 & 2.)

Helix sordulenta Morelet, Journ. Conchyl. [Paris] 1851, vol. ii, p. 856; Le-
tourneux & Bourguignat, Explorat. Scient. Tunisie (Prod. Mal. Terr. Fluyv.)
1887, p. 10.

Helicella (Fruticicola) sordulenta Tryon, ‘Manual of Conchology’ 1887,
Sera), vol. i, plixxxix, fess 1G 259.177.

Hygromia (Fruticicola) sordulenta Pilsbry, Tryon’s ‘ Manual of Conchology’
1894, ser. 2, vol. ix, p. 275.

Remarks.—tThis species was originally described from Con-
stantine, in Algeria, and has since been recognized by Letourneux
& Bourguignat from localities in Tunisia.

Occurrence.—Associated with a reddish-brown loamy material.

Locality.—Bonmansur, south of Derna.

1 *Géologie du Sahara Algérien—Chemin de Fer Transsaharien’ French

Government Report [Paris] 1890, pp. 158, 194, &c. & pl. xxviii, figs. 20-21.
GG, oN 0.208. 2U

620 MR. R. B. NEWTON ON [Nov. 1911,

HELIcELLA TUBERCULOSA (Conrad). (Pl. XLITI, figs. 3-5.)

Caracolla tuberculosa Conrad, in W. F. Lynch’s ‘ Official Report of the U.S.
Exped. Dead Sea, &c.’ 1852, pl. xxii, fig. 1382 & p. 229.

Helix tuberculosa von Martens, Sitz-Ber. Gesellsch. Naturf. Freunde Berlin
(‘ Landschnecken & Reptilien aus der Cyrenaika’) 1888, p. 147.

Helicella (Turricula) tuberculosa Tryon, ‘ Manual of Conchology ’ 1888, ser. 2,
vol. iy, p. 25.

Remarks.—This species, which assumes roughly the character-
istics of a Z'rochus, as indicated in the original description, is repre-
sented by beautifully preserved specimens of variable dimensions :
the smallest having a length and basal width of 3 millimetres in
both directions, the largest measuring 15 mm. in length and the same
in width, which is an unusual size for the species. The shell was
originally described from the Dead Sea region; von Martens has
recorded it, from Benghazi, in Cyrenaica, and Bourguignat from
Southern Syria, near Jerusalem, and probably from Arabia Petreea.’

Occurrence.—In a reddish-brown sandy-looking soil.

Locality.—Plain east of Benghazi.

The Marine post-Pliocene (Recent Beds) Mollusca from the
Beach-Deposits of Benghazi.

Gastropoda.

CeritHium cf. vuLGATUM Bruguicre.

Cerithium vulgatum Bruguiére, Encycl. Méth. (Vers) 1792, vol. i, pt. 2, p. 481 ;
Sacco, ‘ Moll. Terr. Terz. Piemonte’ 1895, pt. 17, pl. 1, figs. 15-84 & pp. 6-11
(and varieties) ; P. Bédé, Feuille des Jeunes Naturalistes, 1904, No. 408, p. 4.
Remarks.—Consists of a fragmentary worn specimen. Prof.
Sacco regards certain varietal forms as ranging through the
Miocene (Helvetian) and Pliocene rocks ; while M. Paul Bédé has
recognized the species in the more ancient Quaternary deposits
of Tunisia (Sfax), and the mollusc thrives at the present day in
southern European seas.

CoLUMBELLA RusTIcA (Linneeus).

Voluta rustica Linnzus, ‘Systema Nature’ 1758, ed. 10, p. 731.
Colombella rustica Lamarck, ‘ Hist. Nat. Anim. sans Vert.’ 1822, vol. vii, p. 293 ;

Tryon, ‘ Manual of Conchology’ 1883, vol. v, pl. xlii, figs. 34-49 & pl. xliv, |

figs. 50-56, p. 107; P. Bédé, Feuille des Jeunes Naturalistes, 1904, No. 408,
p. 2.

Remarks. — An imperfect worn example referable to this
species is in the collection. The shell does not appear to have been
recognized by Prof. Sacco in the Italian Pliocene, but M. Paul Bédé
records it from the more recent Quaternary beds of Tunisia (Sfax),
and the form is well known as living in the Mediterranean and
Atlantic.

1 ‘Moll. Nouy. Litigieux ou Peu Connus’ 18638, pt. 1, pp. 60-63,

ae i
0 RE
3 : _

Vol. 67.] KAINOZOIC MOLLUSCA FROM CYRBENAICA. 620

CHELYCONUS MEDITERRANEUS (Hwass, in Bruguiére).

Conus mediterraneus Hwass, in Bruguiére, ‘ Hist. Nat. des Vers: Moll.’ Encycl.
Méth. 1792, vol. i, pt. 2, p. 701, & ibid. 1798 (edited by Lamarck) pl. ccexxx,
fig. 4,

Chelyconus mediterraneus (varieties) Sacco, ‘ Moll. Terr. Terz. Piemonte’ 1893,
pt. 18, pl. x, figs. 1-15 & pp. 103-107.

Conus mediterraneus Bédé, Bull. Mus. Hist. Nat. [Paris] 1903, vol. ix,
pp. 422-25.

Remarks.—A single specimen has been determined as this
species, but soon after identification it was unfortunately lost.
Prof. Sacco has described varieties from the Upper Tertiary of Italy ;
while M. Paul Bédé records it from the post-Pliocene deposits of
Tunisia (Sfax), and the species lives at the present day.

Pelecypoda.

OstREA EDULIS Linneus.
Ostrea edulis Linneus, ‘Systema Nature’ 1758, ed. 10, p. 699; Sacco, ‘ Moll.
Terr. Terz. Piemonte’ 1897, pt. 23, pls. 1-11 & pp. 4-9.

Remarks.—This form is represented by a single thick and
roughly-worn valve, which partly discloses the ligamenta] area.
According to Prof. Sacco, several varieties of this oyster occur
throughout the Helvetian stage of the Miocene and also in the
Pliocene rocks of Italy. It has also been recognized by various
authors from the post-Pliocene deposits of Mediterranean countries,
England, etc., Messrs. Bellamy & Jukes-Browne mentioning its
occurrence in such beds at Cyprus. The species belongs to the
living fauna of the seas of Europe, etc.

GLYCYMERIS GLYCYMERIS (Linneus).

Arca glycymeris Linneus, ‘Systema Nature ’ 1758, ed. 10, p. 695.
Pectunculus glycymeris Searles Wood (pars), Monogr. Pal. Soc. (British Crag
Mollusca) 1850, pl. ix, figs. 1 a-16b & p. 66.

Remarks.—This species is here restricted to the widely orbicular
examples and not to the more elongate forms, which are regarded
as belonging to the species pilosa of Linnzeus, described in a later
edition of the ‘Systema Nature.’ Its advent dates from Pliocene
times, and it lives at the present day in European seas.

CERASTODERMA EDULE (Linneus). (PI. XLIII, fig. 6.)

Cardium edule Linnzus, ‘Systema Nature’ 1758, ed. 10, p. 681.
Cerastoderma edule Sacco, ‘ Moll. Terr. Terz. Piemonte’ 1899, pt. 27, pl. xi,
fig. 24 (and varieties, figs. 25-32) & pp. 48, 49.

Remarks.—This species and its varieties are regarded as com-
mencing in Pliocene times; it is also now found in the seas of
Europe. The collection contains two left valves from this deposit,
which is regarded as being of more recent origin than those
from the compact limestone to be presently mentioned. According
to M. Paul Bédé,* the species occurs in both divisions of the
Quaternary formations of Tunisia.

1 «Geology of Cyprus’ 1905, p. 41.
2 «Ta Feuille des Jeunes Naturalistes’ 1904, No. 408, pp. 2 & 18.
204

622 MR. R. B. NEWTON ON [Nov. 1911,

Macrra stuttorum (Linneus).

Cardium stultorum Linneus, ‘Systema Nature’ 1758, ed. 10, p. 681.

Mactra stultorum Linneus, ibid. 1767, ed. 12, vol. i, pt. 2, p. 1126; Searles
Wood, Monogr. Pal. Soc. (British Crag Mollusca) 1853, pl. xxiii, figs. 3a-3d
& p. 242.

Remarks.—As well as being a well-known present-day species
(Kuropean seas), this shell has been recognized by Searles Wood as
British Phocene, and by Prof. Sacco, under the Linnean name of
Corallina, from rocks of similar age in Italy. There is but a single
left valve, embedded in matrix, to illustrate this form, showing
external characters.

JAGONIA PECYEN (Lamarck). (Pl. XLII, figs. 7 & 8.)

Tellina reticulata Poli, ‘Testacea Utriusque Sicilie ’ 1795, vol. ii, 2nd Order
(Bivalvia) pl. xx, fig. 14, p. 48 (? 20m Linnzeus).

Lucina pecten Lamarck, ‘ Hist. Nat. Anim. sans Vert.’ 1818, vol. v, p. 543.

Jagonia reticulata Sacco, ‘Moll. Terr. Terz. Piemonte’ 1901, pt. 29, pl. xx,
figs. 65-67 & p. 97; Bédé, Feuille des Jeunes Naturalistes, 1904, No. 408,
p. 3.

Remarks.—tThis species, which forms the type of Recluz’s genus
Jagonia,’ is regarded as ranging from the Tortonian stage of the
Miocene and through the Pliocene (see Sacco); M. Paul Bédé also
recognizes it as occurring in the recent Quaternary deposits of
Tunisia (Sfax). It also lives in the Mediterranean. Only one valve
is in the collection.

Lorrprs nacrevs (Linneus).

Tellina lactea Linneus, ‘ Systema Nature ’ 1758, ed. 10, p. 676.
Lucina leucoma Turton, ‘Conchylia Insularum Britannicarum’ 1822, p. 118,
pl. vil, fig. 8.
Loripes lacteus Sacco, ‘ Moll. Terr. Terz. Piemonte’ 1901, pt. 29, pl. xxix, figs. 1-4
& p. 98; P. Bédé, Bull. Mus. Hist. Nat. [Paris| 1903, vol. ix, p. 422.
Remarks.—The species is common to Miocene (Tortonian) and
Pliocene rocks, and is a member of the recent fauna (Mediterranean),
M. Paul Bédé schedules it among the recent Quaternary fauna of
Tunisia (Sfax).

The Marine post-Pliocene (Ancient Beds) Mollusca.
Pelecypoda. |

GLycYMERIs PILOSA (Linneeus).
Arca pilosa Linneus, ‘Systema Nature’ 1767, ed. 12, vol. i, pt. 2, p. 1143.
Pectunculus glycymeris, Searles Wood, Monogr. Pal. Soc. 1850, pl. ix, fig. 1 d
& p.66; and Monogr. Pal. Soc. 1874 (Supplement), vars. inflatus & insubri-
cus Brocchi, p. 116.
Axinea pilosa Sacco, ‘ Moll. Terr. Terz. Piemonte’ 1898, pt. 26, pl. vii, figs. 4~7
& p. 31.

Remarks.— This specimen consists of a left valve showing
somewhat eroded external characters, the umbonal and hinge-
regions being also seen; otherwise, the interior is filled with
matrix. The surface-striations, both longitudinal and concentric,
present the decussated sculpture of this species. Most authors have
united GU. pilosa with Gl. glycymeris, an earlier described shell of

1 Actes Soc, Linn, Bordeaux, 1869, vol. xxvii, pp. 35-41,

i

Vol. 67.] KAINOZOIC MOLLUSCA FROM CYRENAICA, 623

Linneeus, both found living in the Mediterranean. Deshayes, how-
ever, has pointed out (on the authority of Hanley, ‘Ipsa Linnei
Conchylia’ 1855, pp. 99 & 100) that in Glycymeris glycymeris
the concentric striations are more obvious and the valves generally
more depressed. In addition, it would appear that the contour of
Gl. pilosa is more or less elongate, whereas in the other species
it is usually much rounder.

Dimensions (left valve).— Length = 48 millimetres; height
=52mm.; diameter=20 mm.

Prof. Sacco has recorded this shell from the Tertiary deposits
of Italy, regarding its range as extending from Helvetian times.
It occurs in the Pliocene (Coralline Crag) of England, where
Searles Wood has recognized it under Pectunculus glycymeris,
showing varietal characters of P. inflatus and P. insubricus of
Brocchi.

Occurrence.—The matrix is a cream-coloured limestone,
coated with a thick brick-red rock which is also of calcareous
composition.

Locality.—West of Ptolemeta.

CERASTODERMA EDULE (Linneus). (PI. XLIII, figs. 9 & 10.)

[Additional synonymy to that on p. 621. ]
Cardium crassum Defrance, Dict. Sci. Nat. { Paris] 1817, vol. v, Suppl. p. 106,
vigk pace ; Philippi, ‘ Enumeratio Molluscorum Siciliz ’ 1836, pl. iv, fig. 17
Cann rusticum Eichwald, ‘Fauna Caspio-Caucasia’ 1841, pl. xxxviil,
figs. 26-27 & p. 215, non Linneus.
Cardium edule [pars], wnbonatum, etc., Searles V. Wood, Monogr. Pal. Soc.
(British Crag Mollusca) 1853, pl. xiv, figs. 2a-2.g & p. 155.
Remarks.—This species exhibits many variations, but, speaking
generally, the examples of the present collection appear to favour a
form figured by Searles Wood from the English Crag, called C. edule
var. umbonatum, which has produced and inflated umbones as
well as thick and well-defined coste; it is the same as Hichwald’s
C. rusticum, which lives in the brackish waters of the Aralo-Caspian
region of Europe, being also found fossil in the shore-deposits of
that district. The specimens likewise resemble a fossil from Sicily
described and figured by Philippi as Cardiwm crassum, which, so
far as the figure is concerned, shares all the characters of the
forms from Cyrenaica. The coste are subangulate and ornamented
at first with extremely fine concentric striations which have the
appearance of delicate annulations, these afterwards giving place
to a coarser condition of annulated structure, the segments of
which become so thick that they resemble nodosities. All the
valves are of thick and robust character.
Dimensions (large example with united valves).
40 millimetres; height=30 mm.; diameter=28 mm.
Specimens of this shell are numerous. ‘The species is known
from other areas of Northern Africa, and likewise from most
countries skirting the Mediterranean Sea, in rocks of similar age;
Prof. Sacco and Searles Wood, however, have recognized it in the
Pliocene of Italy and England, and it is besides known as a living

Length=

vio e erty 20

624 MR. R, B, NEWTON ON [Nov. 1911

Mediterranean aud Atlantic species. In post-Pilocene deposits it
has been recognized by d’Archiac from Greeee,’ by P. Fischer
from Asia Minor,’ by M. G. Rolland from localities in Algeria,” by
Dr. Blanckenhorn in the neighbourhood of Alexandria,‘ by M. Beédé
from Tunisia (Sfax),° by Messrs. Bellamy & Jukes-Browne from
Cyprus,° and by Dr. Pachundaki from near Mersa Matruh on the
Marmarican plateau of Northern Africa.’

Occurrence.—The shells are associated with a compact cream-
coloured limestone, and sometimes with a soft, pale, marly-looking
rock ; an external tinge of reddish brown, the result of weathering,
etc., is observed on most of the specimens. The small brackish-
water gastropod Paludestrina (=AHydrobia) occurs in the same
matrix with these specimens.°

Locality.—Plain east of Benghazi.

In Viquesnel’s ‘ Voy, Turquie d’ Europe’ 1855, vol. ii, pl. xxiv, fig. 7 & p. 479.
In P. de Tehihatchefi’s ‘ Asie Mineure’ pt. iv (1866-69) p. 356.

‘Géologie du Sahara Algérien—Chemin de Fer Transsaharien’ French
Government Report [Paris] 1890, pl. xxviii, figs. 20-21 & pp. 158, 194, ete. :
both solid and fragile examples. .

4 «Neues zur Geologie & Palaiontologie Hgyptens—1IV. Das Pliocan- &
Quartarzeitalter’ Zeitschr. Deutsch. Geol. Gesellsch. vol. liii (1901) p. 466.

> Bull. Mus. Hist. Nat. [Paris] vol. ix (1903) p. 423.

° «The Geology of Cyprus’ 1905, p. 51.

* «Contrib. Géol. Marsa Matrouh (Marmarique)’ 1907, pp. 4 & 6.

5 [Since the reading of this paper, a re-examination has been made of the
limestones containing Cerastoderma edule which Prof. Gregory obtained from
‘Plain east of Benghazi.” They exhibit a number of small gastropods and
fragmentary pelecypods which are of importance to include in this account of the
fossil shells of Cyrenaica. The most frequently occurring genus is Paludestrina ;
there are also a Bulimuloid shell, another resembling a Helicoid, a possible Trun-
catella, Nassa (?), fragmentary Cerithiuin like vulgatum, and some imperfect
valves of probably Telliniform shells. Such a fauna would suggest a brackish-
water origin, the deposition of the beds containing the same being due to
lagoon or estuarine agencies rather than to conditions involving true marine
characters.

Bourguignat (‘ Pal. Moll. Terr. Fluy. Algérie’ { Paris] 1862, plates & text) has
described a somewhat similar association of forms from the post-Pliocene
formation of Algeria (the ‘Chotts’ of the Algerian Sahara); while Tournouer
(C. R. Assoc. Frang. Av. Sci. 1879, Sess. vii, pp. 608-22, pl. vi), who sub-
sequently studied the same area, was of opinion that the molluscan evidence
was against the existence of a marine submergence of that part of Northern
Africa during post-Pliocene times. There is another well-known instance of
the occurrence of Paludestrina with Cerastoderma edule presented by the
_Aralo-Caspian region of Western Asia, where these molluscs are found both in
the fossil and in the recent state. An interesting monograph has been published
by Mr. W. Bateson on variations observable in the valves of Cerastoderma
edule (Phil. Trans. Roy. Soc. London, 1890, vol. clxxx, pp. 297-330 & pl. xxvi),
which he regards as due to differences of environment more particularly con-
nected with the varied degrees of the salinity of the waters; the material for
this work was collected by the author from the lake-regions of Northern Egypt
(Mareotis, etc.), as well as from the Aralo-Caspian country.

The limestones from ‘ Plain east of Benghazi’ appear, therefore, to represent
two horizons: the oldest being Vindobonian and entirely marine, with Scutella,
Pecten zizinie, foraminifera, and Lithothamnion; the youngest showing brackish-
water characters from the presence of Cerastoderma edule, Paludestrina, etc.,
which are recognized as belonging to an ancient part of the post-Pliocene
formation. |

wo we

wo

Vol. 67.] KAINOZOIC MOLLUSCA FROM CYRENAICA,. 625

CaRDIUM TUBERCULATUM Linnzeus.

Cardium tuberculatum Linnaeus, “Sy stema Nature’ 1758, ed. 10, P. 679; Sacco,
‘Moll. Terr. Terz. Piemonte’ 1899, pt. 27, pl. ix, figs. 16-17 & op, 40; Bédé,
Feuille des Jeunes Naturalistes, 1904, No. 408, p. 5

‘Remarks.—Two fragmentary left valves represent this species,
showing twenty coste with somewhat eroded summits, yet pre-
serving in places close and equidistant annulations or nodosities
which are more delicate on the face of the shell but larger and
swollen on the anterior surface. Close, squamulose, transverse
striations decorate the remote intercostal grooves. The posterior
side is deep and obliquely truncated.

Dimensions (approximate: largest left valve).— Length =
595 millimetres ; height =65 mm.; diameter=30 mm.

The species is a well-known Mediterranean form. It also occurs
in the Pliocene rocks of Italy, as described by Prof. Sacco and a
number of previous authors, and M. Paul Bédé records it from the
ancient Quaternary deposits of Tunisia (Sfax). This species would
include Cardium rusticum of Linneus, a fact acknowledged by most
eonchologists.

Occurrence.—The matrix associated with these specimens is
a hard siliceous limestone, containing in abundance minute pebbly
fragments of a white material; otherwise, the rock is brick-red
in colour.

Locality.—West of Ptolemeta.

Ill. Heniverran-Torronian.

The Helvetian-Tortonian (=Vindobonian of Depéret) rocks are
particularly well known in various regions of Northern Africa,
having been described by Zittel, Fuchs, the officers of the Geo-
logical Survey of Egypt, Dr. Blanckenhorn, and many other
authorities for Egypt, including Dr. Pachundaki, the last-named in
connexion with the structure of the Marmarican plateau to the
west of Alexandria. The same beds are widely distributed over
Mediterranean countries; and the few fossils from Cyrenaica now
described are fairly well represented in the European development
of this part of the Miocene System. Accompanying the shell-
remains from Gubah are some fragmentary Balanus with probable
affinities to B. concavus of Bronn, a related form of this species
having been recognized by Fuchs in the Helvetian deposits of
Geneffe (Egypt).
_ The other localities recognized as yielding fossils of this age in

Cyrenaica are the Grotto, Lethe ‘ River,’ near Benghazi; the plain
east of Benghazi (which yields a limestone full of Lithothamn'on
and Amphistegina, etc.); and the tract extending from Merj Plain
to Wadi Hamema.

626 MR. R. B. NEWTON ON [Nov. tort,

Gastropoda.

SrromBus cf. cononatus Defrance. (PI. XLIII, fig. 14.)

Strombus coronatus Defrance, Dict. Sci. Nat. [Paris] 1827, vol. li, p. 124
Heernes, ‘ Foss. Moll. Tert.-Beck. Wien ’ 1852, pts. 2-4, pl. xvii, fig. 1 & p. 187 ;
Sacco, ‘ Moll. Terr. Terz. Piemonte’ 1893, pt. 14, pl. i, fig. 19 & p. 7.
Remarks.—Two limestone casts represent a form of Strombus
allied to the coronatus of Defrance, the true species being known
under different names (see Heernes and Sacco for the synonymy)
having been described from France, Poland, Italy, Austria (Vienna
Basin, etc.), the Morean region of Greece, etc., besides a related
form determined by Fuchs from the Pyramids district of Egypt.
Its range in time is regarded by Prof. Sacco as extending from
the Tortonian division of the Miocene to the Astian Group of the
Phocene System. The specimens are of moderate size, exhibiting
a widely spiral region with three or four tabulate whorls separated
by a canaliculate suture; the aperture is elongate and narrow, while
the columella terminates with a long and prominent excavation.
The surface shows some very obscure concentric striations just
below the summit margin of the body-whorl, and there are indi-
cations besides of distant nodulations on the same margin, from
which extend obliquely some obscure growth-lines. This form
is considered to be in closer relationship to Strombus coronatus
than to Str. bonellt of Brongniart, on account of the great width
of the summit-region, the latter species being relatively longer
and more slender in its general contour.
Dimensions.—Length=85 mm. ; width (frontal) =62 mm.
Occurrence.—The specimens are associated with a cream-
coloured compact limestone, which has weathered reddish-brown,
and is apparently full of foraminifera (Amphistegina ?, etc.).
Locality.—Gubah.

Pelecypoda.

Asecrryonia ef, pricaruta (Gmelin), (Pl. XLITI, fig. 11°)

Ostrea plicatula Gmelin in Linneus, ‘Systema Nature,’ 1790, ed. 13, vol. 1,
pt. 6, p. 3336.
Alectryonia plicatula Sacco, ‘ Moll. Terr. Terz. Piemonte,’ 1897, pt. 23, p. 19.
Remarks.—I am inclined to place here a single lower valve
attached to matrix, of an ostreiform shell showing external cha-
racters only. It is of rounded contour dorsally, posteriorly, and
ventrally, but truncated and obliquely margined in the anterior
area ; the surface is generally depressed, its chief convexity being
in the posterior region ; the ornamentation consists of a series of
five or six radial plications equidistantly separated, which bifurcate
about midway and terminate in rounded tubular extremities.
Dimensions (lower valve).—Length=50mm.; height =47mm.;
diameter=15 mm.
The specimen compares favourably with O. plicatula of Gmelin,
a recent Mediterranean species which has both its valves plicated,

Vol. 67.| KAINOZOLC MOLLUSCA FROM CYRENAICA. 627

and is hence regarded as an Alectryonia. According to Prof. Sacco,
A. plicatula and its varieties range from Helvetian to the Astian
division of the Phocene in Italy, ete.
Occurrence.—In a light yellowish cream-coloured limestone,
associated with Operculina and Balanus ct. concavus Bronn.
Locality.—Gubah.

ALECTRYONIA cf, viRLETI (Deshayes).

Ostrea virleti Deshayes, ‘ Expéd. Sci. Morée’ 1833, vol. iii, pt. 1 (Mollusques)
pl. xxi, figs. 1-6 & pp. 122-24 (=pseudoedulis and excavata Deshayes) ; Fuchs,
Denkschr. K. Akad. Wissensch. Wien, 1879, vol. xli, pt. 2, pl. iv, figs. 1-9
& p. 106; Paleontographica, 1883, vol. xxx, pls. ix-x [iv-v] & p. 43 [61].

Alectryonia virleti R. B. Newton, Geol. Mag. 1899, p. 208.

Remarks.—Scattered through a limestone are some fragments of
an ostreiform shell, which show a regular and prominently plicated
ventral region producing widely flexuous margins, and resembling
most strongly what is present in examples of O. virleti, a species
characteristic of Helvetian-Tortonian times, besides extending to
the Pliocene, and is found in most Mediterranean regions, such
as the Morea, Russian Armenia, Persia, Egypt, etc. It has quite
recently been recognized in the base of the Helvetian Series, near
Mersa Matruh (Marmarica), west of Alexandria, by M. G. F.
Dollfus.*

Occurrence.—The matrix is a cream-coloured limestone, wea-
thering reddish-brown. From a microscopical examination, it is
found to be largely composed of Orbitoides, Amphistegina, and Litho-
thamnion, and may therefore be regarded as of Helvetianage. Such
evidence, however, is against the views of the Archduke Ludwig
Salvator, that author having recognized the rock as of Nummulitic
age, a statement which makes it possible that the Amphisteqine were
formerly included under the more general term of Vumnwulites.

Locality.—The Grotto, Lethe ‘ River,’ near Benghazi.

PEcTEN Z1ZINIm Blanckenhorn.

Pecten tournali Fuchs, Denkschr. K. Akad. Wissensch. Wien, 1878, vol. xxxviil,
pt. 2, p. 37, non Serres.

Pecten solarium Fuchs, Paleontographica, 1883, vol. xxx, pp. 33, 40, & 57,
non Lamarck.

Pecten solarium, var. egyptiacus Blanckenhorn, Centralblatt Mineral. &c.
[Stuttgart] 1900, p. 212.

Pecten zizinie, Blanckenhorn, Zeitschr. Deutsch. Geol. Gesellsch. 1901, vol. ]iii,
p. 123, and Neues Jahrb. 1903, Beil.-Band xvii, pls. xiii-xiv & p. 167;
Depéret & Roman, Mém. Soc. Géol. France, 1905, vol. xiii, pt. 2, No. 26,
pl. ix, figs. 3-5 & p. 80.

Remarks.—Only the upper valve of this shell is preserved ;
although of imperfect condition and attached to a solid limestone-
matrix, it has all the essential features of the species as originally
described by Dr. Blanckenhorn and further remarked upon and
figured by MM. Depéret & Roman. It seems to possess the dorso-
median gibbosity which is characteristic of the species; otherwise,
the valve is depressed.

Dimensions.—Length =about 80 mm.; height=about 70 mm.

1 In D. E. Pachundaki’s ‘ Contrib. Etude Géol. Marsa Matrouh’ 1907, p. 35.

628 MR. BR. B. NEWTON ON (Nov. 1911,

This species is essentially Egyptian, having been found in the
rocks at Siwa, Gebel Geneffe, Wadi Haggu, etc., and near Sinai.
A related form occurs in the Lower Helvetian beds of the Mar-
marican plateau near Alexandria, which has been recorded as
Pecten (Macrochlamys) cf. zizinice of Blanckenhorn.!

Occurrence.—The matrix consists of a cream-coloured limestone,
within a thick rim of compact reddish-brown limestone; a micro-
scopical section shows foraminifera and algee—sueh as Operculina,
humerous specimens of Amphistegina, and Lithothamnion.

Localities.—Dr. Blanckenhorn mentions this species as occur-
ring also at Mersa Badia and Mersa Tobruk. The present specimen
was found on the plain east of Benghazi.

Anapara ef. tuRonIcA (Dujardin). (Pl. XLII, figs. 12 & 13.)

Arca turonica Dujardin, ‘Les Couches du Sol en Touraine’ Mém. Soc. Géol.
France, 1837, vol. ii, pl. xviii, fig. 16 & p. 267; Hoernes, ‘ Foss. Moll. Tert.-Beck.
Wien’ 1864, pl. xliv, fig. 2 & p. 332.

Anadara turonica Sacco, ‘ Moll. Terr. Terz. Piemonte’ 1898, pt. 26, pl. v, fig. 14
& p. 24.

Remarks.—The specimens herewith determined consist of
internal casts and impressions in a sandstone. Apparently the costee
vary numerically in the true A. turonica, as, according to Dujardin,
from twenty-six to twenty-eight are seen in examples from France,
whereas Vienna-Basin specimens, according to Hoernes, possess
thirty-five. The forms from Cyrenaica have a still greater number ;
and, although this is difficult to estimate exactly, it is probable that
they possessed between forty and fifty ribs, which are consequently
finer and much more microscopical in details of structure. ‘These
coste, however, possess the usual minutely nodulated summits of
this species, as well as the delicately transverse striations decorating
the intercostal grooves. In general contour, also, the present speci-
mens agree quite well with this species. Prof. Sacco regards it as of
Helvetian age, and previously Theodor Fuchs had determined Arca
cf. turonica from the Miocene deposits of Siwa in Egypt.*

Dimensions.—Length=25 mm.; height=15 mm.

Occurrence.—These casts and impressions are found in a fine
cream-coloured sandstone, weathering reddish brown.

Locality.—Found on the traverse from Mer} Plain to Wadi
Hamema.

LV. AQUITANIAN.

Included in the Aquitanian Series are certain marine Pelecypoda
which show a relationship to the ‘ Schioschichten’ fauna of Northern
taly. They consist largely of pectinoid shell-remains furnished
with costal systems of highly ornamental designs, which were ob-
tained chiefly from the Ain-Sciahat area of Cyrenaica—the rocks of

See D. E. Pachundaki, ‘Contrib. Etude Géol. Marsa Matrouh (Mar-
marique)’ Revue Internationale d’Egypte, vol. iv, pt 11 (1907) p. 12.
? Paleontographica, vol. xxx (1888) p. 33.

Vol. 67.] KAINOZOIC MOLLUSCA FROM CYRENATCA. 629

that region being mostly grey, sandy-looking limestones containing
well-preserved forms of Operculina. Further pectinoid shells col-
lected at Wadi Umzigga and Birlibah, and exhibiting a much simpler
costal structure, are associated with a matrix varying from a com-
pact cream-coloured limestone to a yellowish arenaceous rock with
minute blackish mineral grains and externally weathering to a light
reddish-brown, which has yielded examples of Lepidocyclina ele-
phantina Munier-Chalmas,' together with other orbitoidal organisms
and Operculina. In none of these rocks mentioned as Aquitanian
has the true Nummulites been observed.

Aquitanian deposits have not been recognized by Dr. Blancken-
horn as occurring in Egypt,” the lowest Miocene determined being
the Langhian or Burdigalian stage, which is developed in the
Moghara district of the Libyan Desert. A similar statement would
probably apply to the other divisions of Northern Africa, although
in Eastern Africa and Madagascar, according to A. de Lapparent’s
manual,’ Aquitanian beds occur with Lepzdocyclina and Litho-
thamnion. As stated previously, some of the species recorded here
as Aquitanian resemble the ‘ Schioschichten’ fauna of Northern
Italy, but there are others which exhibit a facies belonging more
to the Burdigalian or Helvetian type, such as Mguwipecten zittels,
44. camaretensis, and A@. scabrellus, and yet occurring in matrix
similar to that associated with Pecten vezzanensis, diquipecten
ef. pasinu, and Spondylus cisalpinus. This mixture of forms is
interesting although not unknown, as Dr. Oppenheim’s memoir on
the ‘Schioschichten’ refers to some pelecypods which are more
usually recognized as Burdigalian or Lower Helvetian, rather than
Aquitanian.*

Pelecypoda.
Osrrea cf. caupata Minster. (Pl. XLIV, fig. 1.)

Ostrea caudata Miinster in Goldfuss, ‘Petrefacta Germanie’ 1833, vol. i,
pl. Ixxvu, figs. 7 a-7d & p. 17.
hemarks.—The specimen thought to be related to this species
is a lower valve, the exterior of which is in a very worn condition.
It is of deltoid contour, very convex, and with a well-rounded
posterior border; the anterior side is elevated, more or less abrupt,
distinctly truncated near the ventral corner, and possessing an
attachment cavity which occupies more than half the area of the
shell. The surface exhibits a lamellar structure which appears to
be crossed at distant intervals by very obscure radial plications.
The interior is filled with matrix.
Dimensions (lower valve).— Length= 48 millimetres; height=
50 mm.; depth=20 mm.

' See Mr. Chapman’s paper on the Foraminifera of this collection (p. 660).
Zeitschr. Deutsch. Geol. Gesellsch. vol. liii (1901) pp. 52, ete.

* <Traité de Géologie’ 5th ed. (1906) p. 1597.

4 Zeitschr. Deutsch. Geol. Gesellsch. vol. ly (1903) pls. viii-xi & pp. 98-235.

630 MR. R. B. NEWTON ON [Nov. rgtt,

The true O. cawdata belongs to the Miocene regions of Germany
(Goldfuss, etc.), Egypt (Oasis of Siwa) as recorded by Dr. Blancken-
horn,’ and of the Marmarican plateau near Alexandria as recog-
nized by M. G. F. Dollfus,? and is regarded as of Lower Helvetian
age.

Occurrence.—Matrix of a reddish-brown colour and full of
foraminifera (Operculina, etc.).

Locality.—Kast of the shrine of Sidi Mahomet Mahridi, east of
Slonta.

Osrrea crassicosrata G. B. Sowerby. (Pl. XLV, figs. 1 & 2.)
Ostrea crassicostata G. B. Sowerby, Q. J. G. S. 1847, vol. i, pl. xix, fig. 23
& p. 420; Heernes, ‘ Foss. Moll. ert.-Beck. Wien’ 1870, pl. Ixvii, fig. 4,
ae 4 A. P.da Costa, ‘ Moll. Tert. Portugal’ Comm. Serv. Géol. Portugal,
Ostrea Bachata Oppenheim, Zeitschr. Deutsch. Geol. Gesellsch. 1903, vol. iy,
pp. 151-82.

Remarks.—The best of two specimens is a fine example of
Sowerby’s shell originally described from Portuguese Tertiary beds,
now regarded as of Lower Burdigalian age.* Only the lower valve
is preserved, but it is exceedingly thick and robust, exhibiting on
the dorsal surface the nearly equidistant and few longitudinal
plications so characteristic of the species. The interior possesses a
moderately excavated area, a deeply impressed anterior muscular
scar of large size with a concentrically banded surface, and a short
and broad ligamental area.

Dimensions.—Length = 75 millimetres; height = 90 mm.;
thickness=50 mm.

According to Hoernes the species ranges from the lower beds of
the Horner Schichten (=Agquitanian) to the Leithalkalk (=Torto-
nian) of Vienna Basin localities; and, as previously stated, it
belongs to the Lower Burdigalian deposits of Portugal and the
Aquitanian of Italy.

Occurrence.—Next to no matrix is associated with these speci-
mens, and both have a generally reddish-brown colour ; no forami-
nifera are discernible.

Localties.—East of the shrine of Sidi Mahomet Mahridi, east
of Slonta. The thick example comes from west of Lamludeh.

SPONDYLUS CIsALPINUS Brongniart. (Pl. XLIV, fig. 2.)

Spondylus cisalpinus A. Brongniart, ‘ Mém. Terr. Séd. Supér. Calcaréo-Trapp.
du Vicentin’ 1828, pl. v, figs. la-le & p. 76; Fuchs, ‘ Beitr. Conchyl.
Vicentinischen Tertiargeb.’ Denkschr. K. Akad. Wissensch. Wien, 1870,
vol. xxx, pt. 2, pl. vii, figs. 11-12 & p. 168; Heernes, ‘ Beitr. z. Kenntn. Tert,
Ablag. Siidalpen (Schioschichten) ’ Jahrb. K.K. Geol. Reichsanst. 1878,
vol. xxviii, p. 29; Oppenheim, Paleontographica, 1901, vol. xlvii, p. 141, and
Zeitschr. Deutsch. Geol. Gesellsch. 1908, vol. lv, p.175.

Remarks.—A single example with both valves in the closed
condition represents this species. It 1s quite a limestone specimen

* Zeitschr. Deutsch. Geol. Gesellsch. vol. liii (1901) p. 109.
2 In D. E. Pachundaki’s ‘Contrib. Etude Géol. Marsa Matrouh (Mar-
marique)’ Rerue Internat. Egypte, vol. iv, pt. ii (1907) p. 12.
3 See F. A. P. da Costa, op. cit. pp. 3 et segq.

Vol. 67.] KAINOZOIC MOLLUSCA FROM CYRENAICA. 631

with no actual shell remaining; and the surface has evidently been
subjected to some erosive action, as the costal system is very
depressed and in places obscure. The umbonal region is not
preserved. Both the valves are of nearly equal convexity, the
lower being well vaulted and of greater height than the upper, and
ornamented with numerous longitudinal more or less unequal coste
separated by narrow grooves, more prominent cost being placed
at equal distances over the surface, with two or three finer subsidiary
ones between. ‘There are faint indications of distant concentric
lineations, as well as obscure evidence of asperities on the primary
longitudinal ribbing. ‘This specimen in its oblong, oval contour and
general structure of the surface-sculpture resembles Fuchs’s inter-
pretation of Brongniart’s species Sp. cisalpinus, which was obtained
from the Grumi Mountains of Castel-Gomberto, Northern Italy, and
is regarded as of Oligocene (Stampian) age. The specimen figured
by Fuchs is larger and in better condition than the original, which
was collected in the same area of Northern Italy, but in rocks said
to be ‘Schioschichten’ and therefore of Aquitanian age. Both
Heernes and Oppenheim have recognized the species in similar
rocks, while the latter author has also identified it as part of the
Priabonian fauna. The species, therefore, ranges from the Pria-
bonian to the Aquitanian.

Dimensions.—Length=58 millimetres; height (approximate) =
80 mm.; diameter 35. mm.

Occurrence. —The matrix is pale and of marly character, with
a reddish tinge in places. Microscopically it is made up of itis
thamnion, Oper culina, etc., but without Nummulites.

Locality. —Ain Sciahat (above camp).

PrcTEN VEZZANENSIS Oppenheim. (Pl. XLV, figs. 3 & 4.)

Pecten arcuatus R. Hernes, Jahrb. K.K. Geol. Reichsanst. vol. xxviii (1878)
pp. 18, 29, non Brocchi.

Janira arcuata Vinassa de Regny, Boll. Soc. Geol. Ital. vol. xv (1896) p. 204.

Pecten (Janira) vezzanensis Oppenheim, Zeitschr. Deutsch. Geol. Gesellsch.
vol. lv (1903) pl. ix, figs. 6-7 a & p. 173.

Remarks.—Dr. Oppenheim has described and figured a small
shell called Pecten vezzanensis, from the Aquitanian (Schioschichten)
rocks of Vezzan near Belluno, in Northern Italy, which had been
previously referred to in literature by Dr. Heernes and Dr. P. Vinassa
de Regny as P. arcuatus, a species characteristic of the Priabonian
horizon.

The specimen now assigned to this species consists of one lower
valve attached to some matrix, possessing twenty-one rather smooth-
topped ribs with minute transverse striations decorating the inter-
mediate furrows; the ears are proportionately deep, the surface of
the byssal one being ornamented with three or four radial coste,
crossing a set of closely arranged, fine, vertical striations, while
the other is furnished with very obscure oblique lines. The um-
bonal area is narrow, less incurved than in other related forms,
and possessed of fairly long concave lateral margins which meet a
well-rounded ventral border. The valve is also moderately convex,

|

632 MR. R. B. NEWTON ON [Nov. 1911,

Dimensions (lower valve).— Length = 15 millimetres; height =
15 mm.

Occurrence.—In a greyish marly-looking rock containing
obscure Operculina.

Locality.—Ain Sciahat.

/Kquipecren cf, pasintt (Meneghini). (Pl. XLIV, figs. 4 & 5.)

Pecten pasinii Meneghini, ‘ Pal. Sardaigne’ 1857, pl. H, fig. 13 & p. 591;
Schafier, Jahrb. K.K. Geol. Reichsanst. 1900, vol. xlix, pl. xvii, figs. 1-36 &
p. 661; Oppenheim, Zeitschr. Deutsch. Geol. Gesellsch. 1903, vol. lv, pl. ix,
figs. 2-3 & p. 162.

Remarks.—In the various figures of Pecten pasinti the dimen-
sions of the valves show a greater length than height, thus differing
from Cyrenaican examples, which are of equal measurement in those
directions, namely 43 millimetres for the largest valve. The sculp-
ture, which is similar on both valves, is, however, somewhat the
same as in Meneghini’s shell: that is, the coste and grooves are
furnished with closely-set, extremely fine, regular, and concen-
trically imbricating striations, this last character appearing to
be less accentuated than in the true P. pasiniz, where the striations
are of rather simpler structure. Meneghini’s P. pasinia was ori-
ginally described from Sardinia, and more recently it has been
recognized from Monte Brione in the Tyrol by Dr. Schaffer, and
from Italian localities by Dr. Oppenheim, the latter author regarding
the species as of Aquitanian age (‘Schioschichten ’).

One of the small specimens 1s attached to an example of Mquipecten
camaretensis and another to Aiquipecten zittelr.

Occurrence.—In a grey marly matrix containing Operculina ;
and a doubtful fragment in a greensand matrix, weathering red,
from Birlibah.

Localities.—Fountain of Apollo, Cyrene (British Museum
specimen——L 16342); and Ain Sciahat, above camp; ? Birlibah.

AXQUIPECTEN ZITTELI (Fuchs). (Pl. XLV, figs. 7 & 8.)

Pecten zitteli Fuchs, Paleontographica, 1883, vol. xxx, pl. vii (i1) figs. 1-12 &
p. 41 (23).
Pecten (Chlamys) zitteli Kilian, ‘Mission d’Andalousie’ Mém. Acad. Sci.
France, 1889, ser. 2, vol. xxx, pl. xxxiu, fig. 9 & p. 709.
Aiquipecten zitteli Sacco, * Moll. Terr. Terz. Piemonte’ 1897, pt. 24, p. 31.
Pecten (Afquipecten) zitteli R. B. Newton, Geol. Mag. 1899, p. 209; Blancken-
horn, Centralblatt Mineral. &c. [Stuttgart] 1900, p. 211, and Zeitschr.
Deutsch. Geol. Gesellsch. 1901, vol. liii, p. 108. _
Pecten zitteli Dollfus, in Pachundaki, ‘Contrib. Etude Géol. Marsa Matrouh
(Marmarique) ’ Revue Internat. Egypte, vol. iv, pt. ii, 1907, p. 32.
Remarks.—Quite a number of pectinoid shells appear to be
referable to this species, which belongs to the Helvetian beds of
Egypt (Siwa Oasis, etc.) and the Marmarican Plateau near Alexan-
dria. From its variability in sculpture the species is often difficult
to determine, the Cyrenaican specimens offering no exception to
this changeable character of the ornament. Some of the valves
exhibit slightly tripartite or divided coste, whereas others are
more rounded; lines of minute granulations frequently cover

the grooves and the sides of the coste, while an extremely fine

Vol. 67.| KAINOZOIC MOLLUSCA FROM CYRENAICA. 633

imbricated surface adorns the summits of the coste. The valves
vary in size as the originals figured by Fuchs, being generally of
the same length as height, one of the largest yielding the following
measurements:—Dimensions (left valve).—Length=43 ire

metres; height=43 mm.

Occurrence.—Mostly in a marly-looking greyish limestone,
sometimes weathering reddish-brown, with Operculina and Litho-
thamnon.

Localities.—Cyrene; Ain Sciahat; Ain Sciahat, above camp ;
before the shrine of Sidi Mahomet Mahridi, east of Slonta; west ae
Labruk.

AMQUIPECTEN CAMARETENSIS (Fontannes). (Pl. XLV, figs. 5 & 6.)

| LOTR pe adap a ne Tert. Bassin du Rhone: pt. 3,

Remarks.—this form of pectinoid shell is represented by several
specimens in different states of preservation, although a more com-
plete valve is available for examination which does not belong to
Prof. Gregory’s collection, but was presented to the British Museum
(Natural History) some time since by Mr. Hf. Weld-Blundell, who
obtained it from the rocks at the Fountain of Apollo, Cyrene. It
shows the subrotund and characteristic form of the species, together
with the sixteen or seventeen rounded radial coste widely sepa-
rated in the ventral region and covered with numerous delicate
squamose concentric lines, the intermediate grooves being orna-
mented with longitudinal rows of minute scabrous growths. Parts
of both auricles are present, ornamented with fine lines of radial
granulations.

Dimensions (left valve).—Length=50 mm.; height=50 mm.

The species is characteristic of rather low Helvetian, being found
in the Visan area of France with Ostrea crassissima, as originally
mentioned by Fontannes. A varietal form is figured and referred
to by Prof. Sacco as occurring in corresponding beds of Italy,’ which
he includes under Matheron’s P. scabriusculus ; while Dr. blancken-
horn records a related form (cf. camaretensis) from the Miocene of
Barka in Cyrenaica.”

Occurrence.—The specimens are in a greyish sandy matrix
containing Operculina.

Localities.—Fountain of Apollo, Cyrene; Ain Sciahat, above
camp; Ain Sciahat.

ZEQUIPECTEN SCABRELLUS (Lamarck).

Pecten scabrellus Lamarck, ‘ Hist. Nat. Anim. sans Vert.’ 1819, vol. vi, pt. 1,

p- 183.
Aiquipecten scabrellus Sacco, ‘Moll. Terr. Terz. Piemonte’ 1897, pt. 24 ili
figs. 1-6 & p. 24. igs aie
Remarks.—According to Prof. Sacco, this species is character-
istic of the Helvetian Miocene, although certain varieties occur in

1 * Moll. Terr. Terz. Piemonte’ 1897, pt. 24, pl. ix, fig. 2 & p. 32.
2 Zeitschr, Deutsch, Geol. Gesellsch, vol, liii (1901) pp. 104, 108, 128,

634 MR. R. B. NEWTON ON (Nov. 1911,

Pliocene strata. In contour it presents generally an oblique
appearance, bearing some fifteen radial coste divided by well-
pronounced sulcations, which are furnished with a squamose-denti-
culate surface. The valves generally have about the same dimensions
each way, one showing a measurement of 33 mm. in length and
height.

Occurrence.—lIn a grey marly-looking matrix, associated with
good examples of Operculina.

Localities.—Ain Sciahat, above camp; Ain Sciahat, Tombs of
Cyrene (= Weld-Blundell Collection, British Museum).

AMQUIPECTEN HAUERI (Michelotti). (PI. XLIV, fig. 6.)

Pecten magnificus Michelotti, Ann. Sci. Inst. Lombardo- Veneto, 1839, vol. ix,
p. 127, non G. B. Sowerby, 1835.

Pecten haueri Michelotti, ‘Descr. Foss. Terr. Miocénes Italie Septent.’ 1847,
pl. iii, fig. 13 & p. 88.

Aiquipecten haueri Sacco, ‘Moll. Terr. Terz. Piemonte’ 1897, pt. 24, pl. vii,
figs. 1-10 & p. 22.

Pecten haueri Oppenheim, Zeitschr. Deutsch. Geol. Gesellsch. 1903, vol. lv,
pl. vin, fig. 5 & p. 154.

Remarks.—Referred to this species is a fragmentary valve, with
obscure remains of auricles, but which in seulptural characters and
general contour appears to completely agree with this form of
pectinoid shell.

The greater part of the umbonal surface is preserved, together
with a few of the coste on the left side of the specimen, otherwise
the remainder is stripped of its test and appears as an internal cast.
About eighteen coste can be counted, which are fine and well
rounded in the umbonal area, but afterwards become flattened and
spreading, especially at the flanks. The early ribs are micro-
scopically and closely imbricated. The great feature of the shell,
however, concerns the numerous close radial lines made up of
microscopical granulations which give a divided or tripartite cha-
racter to the coste as well as decorating the intermediate sulcations.
Distant concentric striations are also present.

Dimensions (approximate).—Length = 65 millimetres; height=
55 mm.

This species was originally described from Northern Italy in
beds now regarded as of Helvetian age; in recent years Dr. Oppen-
heim has recognized it as part of the ‘ Schioschichten’ fauna, and
consequently as belonging to the Aquitanian horizon.

Occurrence.—In a cream-coloured limestone with minute black
specks of mineral matter, and externally weathering to the usual
reddish-brown ferruginous colour; it contains Operculina.

Locality.—Birlibah.

Ooprcten RoTUNDATUS (Lamarck). (Pl. XLIV, fig. 3.)

Pecten rotundatus Lamarck, ‘ Hist. Nat. Anim. sans Vert.’ 1819, vol. vi, pt. 1,
p. 179; Deshayes, 2nd ed. of same work, 1836, vol. vii, p. 156; Fuchs,
Denkschr. K. Akad. Wissensch. Wien, 1879, vol. xli, pt. 2, pl. u, figs. 1-2 &
p. 104; Fontannes, ‘ Etudes Stratigr. Paléont. Période 'Tert. Bassin du
Rhone: le Bassin de Crest ’ 1880, vol. vi, pl. v, fig. 1 & p. 161.

Vol. 67.] KAINOZOIC MOLLUSCA FROM CYRENAICA. 635

Oopecten rotundatus Sacco, ‘ Moll. Terr. Terz. Piemonte’ 1897, pt. 24, pl. xv,
figs. 14-15 & p. 54.

Pecten (Oopecten) rotundatus R. B. Newton, ‘ Marine Tertiary [Miocene]
Mollusea from Lake Urmi, Persia’ Linn. Soc. Journ. (Zool.) 1900, vol. xxvii,
pl. xxix, fig. 1 & p. 443.

Remarks.—The pectinoid shells referred to this species have
well accentuated coste varying in number like the original from
about fourteen to sixteen, which are at first well rounded but later
become more or less depressed at the summits; both the costz
and furrows widen out ventrally and are of equal width. The
surface of the valve is covered with closely-set concentric striations,
which are more obscure over the umbonal region. The best-
preserved specimen in the collection shows an almost similar length
and height of about 70 millimetres, but the margins are by no
means perfect, otherwise it is possible that the length may have
exceeded the height, as in normal forms of the species; the auricles
are only partly seen. The species was originally described from
Vence, between Grasse and Nice in France, under the following
diagnosis :—testa suborbiculari utrinque convexa; radilis
14 ad 16 distinctis, convexis, versus limbum planu-
latis, two figures in Knorr’s old folio work! being mentioned as
examples; but it is evident, as pointed out by Deshayes, that they
belonged to entirely different forms of pectiniform shells ; more-
over, one (op. cit. fig. 5) was from Malta, the other (fig. 6) was
from Algiers. The figure of the Maltese specimen comes probably
nearest to a proper conception of the present species although of
less size, and as Deshayes explained, it should not be considered the
same shell because only seven costal ribs are present. Bearing in
mind also that this same figure represents an imperfectly preserved
specimen, it is advisable to dismiss it from synonymy, a plan fol-
lowed by most subsequent authors. According to Prof. Sacco the
species ranges from the top of the Aquitanian to the Helvetian in
Italy. Fuchs regarded the Vence forms as of ‘ Horner Schichten’”
age, and consequently Aquitanian or lowest Miocene; Fontannes’s
Rhone Valley specimens were considered as Lower Helvetian ;
while the Persian specimens from the Siokuh Mountains and from
Lake Urmi have been bracketted with the Helvetian or Burdi-
galian stages of the Miocene.

Occurrence.—The matrix varies from a cream-coloured or
greyish limestone to a yellowish, arenaceous marly-looking rock
with minute blackish grains; and all have the usual external
ferruginous tinting. Operculina and Nullipore structures (in valves
from Ain Sciahat) are frequent, besides Lepidocyclina elephantina,
identified by Mr. Chapman (see his report on the Foraminifera of
the present collection, p. 660), who states that it indicates either
a Stampian or an Aquitanian age. The presence of the mollusc,
however, in this case would favour the latter horizon.

Localities.—West of Labruk ; Birlibah ; Wadi Umzigga (second
camp); and Ain Sciahat.

1 «Recueil de Monumens des Catastrophes . . . Pétrifications’ vol. ii (1768)
sect. 1, p. 77 & pl. B1 c, figs. 5-6.

@: 3..G..S:. No: 268. 2x

636 MR. R. B. NEWTON ON [Nov. 1911,

[Luciniform Casts. ]

Remarks.—These specimens consist of a number of casts of
rather small size, which may belong to either Lucina or Diplodonta.
They have very convex and somewhat globular valves, but it is not
possible to determine them either zoologically or geologically. They
are therefore included doubtfully among the Aquitanian series.

Occurrence.—The specimens are composed of a cream-coloured
and fine-grained limestone in which no foraminifera are observable.

Localities.—Lamludeh ; below the Mudir’s House, Ain Sciahat ;
Ain Sciahat.

V. PRIABONIAN.

Quite a large series of the Cyrenaican mollusca are regarded as
of Priabonian age, on account of their resemblance to those found in
the Uppermost Eocene or Lowest Oligocene deposits of the Vicentino
district of Northern Italy. Prof. Suess first gave prominence to
this term for the age of these beds by describing them as the
‘Gruppe von Priabona,’ after the name of that region of Italy.’

The chief authority at the present day on these deposits is un-
doubtedly Dr. Oppenheim,” his memoir on ‘ Die Priabonaschichten
& ihre Fauna’ comprising a voluminous survey of the subject. A
brief allusion may be made to those areas of Northern Africa which
have produced fossils of Priabonian age, and we are probably
indebted to Zittel® for our earliest knowledge of this subject.
During his survey of the Libyan Desert of Egypt, Zittel collected
fossils from certain deposits occurring between Rharten and Aradj
near the Oasis of Siwa in Egypt, which were recognized as equi-
valent to the Priabonian fauna of Northern Italy and resembling
that of the highest Eocene deposits of Switzerland, Hungary
(Bakony Forest), Nice, Biarritz, Cassinelle, Dego, and Gaas. These
Egyptian beds, immediately overlying the NMummulites-qizehensis
Zone and regarded as belonging to the Lutetian series of the Eocene,
contained mollusca which were determined by Mayer-Eymar, as
well as foraminifera studied by De la Harpe, the whole constituting
a fauna which Zittel scheduled as Upper Eocene or Ligurian on
his correlation-chart (op. cit. p. xciii); these fossils included
Ostrea ventilabrum, O. fimbriata, Pecten brarritzensis, Nummulites
Jichtelr, N. intermedia, N. ruetimeyerr, ete.

Dr. Schweinfurth in 1886 and 1889 reported the occurrence of *
the uppermost Eocene strata to the west of Dimé, in the Fayim —
district of Egypt.* Fossils of Tongrian age were determined in the
same year by Mayer-Eymar from near Cairo.’ Further material

1 «Ueber die Gliederung des Vicentinischen Tertiargebirges’ Sitz. K. Akad.
Wissensch. Wien, vol. lviii, pt. i (1868) p. 272.

? Palzontographica, vol. xlvii (1900-1901) pls. i-xxi & pp. 348.

8 Jbid. vol. xxx, pt. i (1883) p. 124.

4 Zeitschr. Gesellsch. Erdkund. Berlin, vol. xxi (1886) p. 141, and Peter-
mann’s Mitth. vol. xxxv (1889) p. 2.

5 Viertelj. Nat. Gesellsch. Zurich, vol. xxxiv (1889) pp. 191-208 & pl. i.

Wolk. 67: | KAINOZOIC MOLLUSCA FROM CYRENAICA. 637

was dealt with in subsequent papers by Mayer-Eymar, based on the
examination of fossils from the same region, among some of the more
typical shells being Natica (Ampullina) crassatina, which the same
author had identified, among Schweinfurth’s uppermost Eocene
fossils from the Dimé area of the Faytm.'

In 1896 Mayer-Eymar * mentioned some imperfect fossils collected
at Kum el Kashab (near Cairo) which he supposed to be Lower
Ligurian and resembling those found near Dimé, as they probably
represented Ostrea cyathula var. fimbriata and Pecten (Nevrthea)
arcuatus, etc. Prof. Depéret published in 1896° some obser-
vations on the Tertiaries of Algeria. He had collected (op. cit.
p- 1117) at Beni-Amram certain fossils including Operculines,
small Cardita, and a small Pecten probably identical with Janira
fallax Michelotti (=Pecten arcuaius), from the Tongrian of Dego.
This limited and incomplete fauna he regarded as analogous to the
Tongrian beds with Nummulites fichteli, of Northern Italy and the
Ligurian Apennines. Priabonian rocks in Tunisia were recognized
by M. Flick in 1900,* his paleontological evidence including such
forms as Scutella and Clypeaster, related to S. striatula and
C. biarritzensis which occur at Biarritz and Priabona in Italy ;
Pecten nucals Locard =P. michelotti D’Archiac, corresponding to
examples from Biarritz having non-carinated cost, and which was
stated to be equally common in the Venetian Alps; another Pecten
showed affinities with P. tripartitus and P. gravest of D’Archiac ;
there was also a variety of Cytherea incrassata and Pholadomya
puschi, found at Salcedo and Sangonini. The author regarded the
facies of this fauna as equivalent to that of the Venetian Alps and
belonging to the uppermost EHocene.

In Dr. Blanckenhorn’s memoir on the ‘ Paleogene’ of Egypt,’ the
Nunmulites intermedius and N.-fichteli Beds of the Aradj district of
Egypt are recognized as of Lower Oligocene or Ligurian age, the
species being again mentioned as occurring in rocks of similar age
in Sinai, Palestine, and Syria. The presence of the Upper Eocene
or Bartonian in the same area (Aradj) is not acknowledged by this
author. He further recognizes the Kum-el-Kashab fossils, in-
cluding Natica crassatina, etc., as of Lower Oligocene or Ligurian
age. On p. 460 of the same memoir Dr. Blanckenhorn regards these
beds as Lower Ligurian, stating them to be the equivalent of the
Upper ‘ Biarritzschichten, Latdorfian, Priabonian, or Ludian of
Northern Italy, the Pyrenees, and Northern Germany.

Similar rocks are present in Algeria, Dr. Pervinquiére having
collected Pecten arcuatus and Ostrea brongniarti at Boghari, this
author remarking that those fossils are found in the Priabonian,
although having their maximum occurrence in the Oligocene.®

1 Bull. Inst. Egyptien, ser. 3, vol. iv (1893) pp. 371-373.
? Ibid. vol. vi (1896) p. 94.
> Bull. Soc. Géol. France, ser. 3, vol. xxiv (1896) p. 1115.
: C. R. Acad. Sci. Paris, vol. exxx (1900) pp. 148-50.
Zeitschr. Deutsch. Geol. Gesellsch. vol. lii (1900) pp. 403-79.
* «Etude Géol. Tunisie Centrale’ 1903 [French Govt. Publication] p. 205.

2x2

638 MR. R. B. NEWTON ON [ Nov. 1911,

Quite recently MM. Louis Gentil & Jean Boussac’ have referred
to the presence of Priabonian rocks in the north of Morocco (near
Tangier) containing Orthophragmina and Nummulites fabiani of
Prever.

It will be observed, therefore, that Priabonian fossils have
been collected in North African countries as well as in Syria and
Palestine, one of the characteristic shells of Tunisia and Algeria
being Pecten arcuatus. In the Siwa district of Egypt the beds
contain Nummulites intermedius and NV. jichteli, besides a number
of mollusca but not including Pecten arcuatus. From Cyrenaica
several examples of this Pecten have been obtained, but the two
species of Nummulites have not been determined by Mr. Chapman
in his report on that group, which suggests a resemblance to the
conditions prevalent in Tunisia and Algeria, where JV. intermedius
appears not to be known.

The European home of the Priabonian rocks is in the Venetian
area of Northern Italy, but they also occur in the Balearic Islands
(Majorca), at Biarritz, in the Swiss, Bavarian, and Hastern Alps, the
Carpathians, Hungary, and the Balkan Peninsula. Such rocks are
to be found also in Armenia,” Asia Minor, India, Madagascar, etc.,
references to all of which must be sought for in Dr. Oppenheim’s
memoir already mentioned. In adopting Priabonian as the
horizonal age for these fossils, it should be quite understood that
it may be regarded either as forming the Uppermost Hocene or the
Lowest Oligocene, and preferably the latter. Various authors who
have studied the Priabonian fauna have differed somewhat as to
its position in the geological series. Zittel regarded it as belonging
to the highest Eocene or Ligurian, Schweinfurth as Upper Hocene,
Mayer-Eymar as both Tongrian and Ligurian, Flick as the Upper-
most Eocene, Dr. Blanckenhorn as Lower Oligocene or Ligurian,
and Prof. Depéret as Tongrian.

These fossils come from the neighbourhood of Slonta, Merj,
Messa, Kuf Narbea, Mersa Susa, Bint, Derna, shrine of Sidi
Abdullah, Wadi Khumas, Ain Hafra, Lamludeh, and Ain Sciahat.

Gastropoda.
Eusrrra cf. possagNENSIS Oppenheim. (PI. XLVI, fig. 11.)

Natica (Euspira) possagnensis Oppenheim, Paleontographica, 1901, vol. xlvii, °
pl. vi, fig. 13 & p. 197.

Remarks.—This specimen consists of a limestone cast with the
two latest whorls only, the posterior portion of the spire not being
preserved,

Although of somewhat smaller size, it has much the form of
Oppenheim’s £. possagnensis, described and figured from the
Priabonian rocks of Possagno in Austrian Italy. The front view

1 Bull. Soc. Géol. France, ser. 4, vol. x (1910) p. 484.
2 See F. Oswald, ‘The Geology of Armenia’ 1906, pp. 427 ez segq.

Vol. 67.] KAINOZOIC MOLLUSCA FROM CYRENATCA. 639

exhibits an inflated body-whorl with an oval aperture of considerable
width, and moreover furnished with a well-rounded external margin.
The dorsal aspect shows an extensive basal whorl with a promi-
neutly tabulated and oblique sutural area, above being a fairly deep

_ penultimate whorl, with a rather compressed surface. The columella
is obliterated by matrix.

Dimensions.—Length=60 millimetres; width=57 mm.

The specimen also shows some resemblance to Lamarck’s Natiea
hybrida* from the European and Egyptian Eocene deposits, in
the possession of a tabulated suture and compressed sides to the
earlier whorls, but that has a comparatively shorter spire and is
generally of more globose contour.

Occurrence.—This cast is associated with a cream-coloured
limestone, weathering reddish-brown, which is largely composed of
Nummulites.

Locality.—East of Ain Hafra, east of Cyrene.

AMPULLINA CRAssATINA (Lamarck).

Ampullaria crassatina liamarck, Ann. Mus. Hist. Nat. (Paris) 1804, vol. v,
p. 83; and ibid. 1806, vol. viii, pl. 1xi, fig. 8.

Natica crassatina Deshayes, ‘ Descr. Coq. Foss. Paris’ 1832, vol. ii, pl. xx,
figs. 1-2 & p. 171.

Natica (Ampullina) crassatina Schauroth, ‘ Verzeichn. Versteinerungen ’ 1865,
p. 202.

Natica crassatina Fuchs, Denkschr. K. Akad. Wissensch. Wien, 1870, vol. xxx,
p. 159.

Megatylotus crassatinus Sacco, ‘ Moll. Terr. Terz. Piemonte’ 1891, pt. 9, p. 13;
and Cossmann, Journ. Conchyl. [ Paris] 1892, vol. xl, p. 355.

Natica (Ampullina) crassatina Mayer-Eymar, Bull. Inst. Egyptien, 1893, ser. 3,
ars eee Blanckenhorn, Zeitschr. Deutsch. Geol. Gesellsch. 1900,
vol. lii, pp. 466-67.

temarks.—This fossil is a moderately large limestone-cast,
which has suffered more or less a dorso-ventral compression. In
general form it is transversely subovate ; the body-whorl, from the
dorsal aspect, is extensive and only moderately convex, and it is
surmounted by two earlier whorls having deep and depressed sides;
otherwise, the further elements of the spire are not preserved. ‘The
suture is canaliculated and slightly tabulate, and the aperture is
ample with a semicircular labrum, but the columelloid details are
mostly obscured by matrix, so that the presence or otherwise of an
umbilical cavity is a little uncertain. Compared with Deshayes’s
figures, the cast In question exhibits a greater breadth, as it possesses
a wider aperture and a more produced curvature to the outer lip.

Dimensions.—Length (approx.)=75 mm.; breadth=70 mm.

This species is chiefly characteristic of Lower Oligocene rocks
(=Tongrian), being known from England, European countries
(France, Italy, etc.), and Egypt, as recorded by Mayer-Eymar and
Dr. Blanckenhorn. The species also extends to the Stampian stage
of the same period, having been identified from the ‘ Gomberto-
Schichten ’ of Italy.

1 See G. P. Deshayes, ‘Descr. Cog. Foss. Paris’ vol. ii (1832) p. 172 &
pl. xix, figs. 17—I.

640 MR. R. B. NEWION ON [ Nov. 1911,

Occurrence.—The specimen is associated with a cream-coloured
limestone containing various forms of foraminifera, including Ortho-
phragmina, ete.

Locality.—Lamludeh.

RosteLtaRia sp. (Pl. XLVI, fig. 10.)

are included two limestone-casts
of fragmentary preservation, both exhibiting parts of the basal and
penultimate whorls. These whorls are depressed and divided by a
prominent suture, the basal being furnished with a median obtuse
angulation from which descends obliquely and conically the
remainder of the whorl to the somewhat tapering extremity. The
aperture is elongate, more or less of oval shape and nearly perpen-
dicular, and at the base of the columella is a deep slit-like cavity
from which originally would have extended a possible narrow
canaliculation. The specimens are of different sizes, and evidently
belonged to fairly large individuals like the Strombus amplus of
Solander = Rostellariu macroptera of Lamarck,’ although the casts
give no indication of the extensive labrum which characterizes that
species.
Dimensions in millimetres :—
Larger specimen. Smaller specimen.
STATA vase coge een pe as 63 D4
Width (front aspect) ... ........ 45 37

It is interesting to note that Dr. Oppenheim’ refers to some
doubtful fragments of a ostellaria found in the Priabonian clays
of Possagno, of the group macroptera, and with resemblances to
R. cf. marceauxi of Deshayes, described and figured by Fuchs from
beds of similar age in Russia (Kalinovka), although the casts from
Cyrenaica show no particular relationship to this last-named form.

Occurrence.—Specimens are associated with a light-coloured
limestone, weathering to a reddish tint, in which Nummultes and
other microzoa are observable.

Localities.—‘ After shrine of Sidi Abdullah’; south-east of
Messa.

GIsoRTIA GigaNnTEA (Munster in Goldfuss). (Pl. XLVI, fig. 8.)

Strombus giganteus Munster in Goldtuss, ‘Petrefacta Germanie’ 1844, vol. iui,
pl. clxix, fig. 3 & p. 14.

Ovula (Strombus) pre Lefévre, Ann. Soc. Malacol. Belgique, 1878, vol. xiii,
pl. in, figs. 1-3, pl. iv, figs. 1-3, pl. v, fig. 1, pl. vi, fig. 1 & pp. 29-40,

Gisortia gigantea Oppenheim, Palzontographica, 1906, vol. xxx, pt. 3, No. 2,
p. 304.

Remarks.—This is a small limestone-cast which may be
referred to Munster’s species, originally described from the Kres-
senberg (Lutetian) Beds.

Dimensions.—Length (approx.)=55 mm.; width=40 mm.

The species is characteristic of the Lutetian stage of the Eocene

1 See G. P. Deshayes, ‘ Deser. Cog. Foss. Paris’ vol. ii (18385) p. 620 &

pls. lxxxiii, fig. 1, lxxxiv, fig. 1, lxxxv, fig. 10.
2 Palzontographica, vol. xlvii (1901) p. 211.

Vol. 67.| KAINOZOIC MOLLUSCA FROM CYRENAICS. 641

System, and is known from Kressenberg and other Central
European localities (Belgium, France, Russia), and Egypt. The
Priabonian form is recognized by Lefévre* as Ovula gigantea var.
hernesi, from Northern Italy (Brendola), which chiefly seems to
differ in the possession of an angulated marginal summit to the
outer wall, although judging from the figures this is not constant,
as some show a well-rounded shoulder to that region; it is, how-
ever, of much larger size, an adult example, according to Lefevre,
measuring 300 mm. in length and 200 mm. in width, whereas
a full-grown form of O. gigantea is said by the same author to
measure 145 mm. in height and 120 mm. in width. The present
specimen has a very similar contour to D’Archiac’s Ovula murchisom
from the Nummulitic rocks of India,” and it is probable that that
species might more correctly be regarded as a synonym of Gisortia
gigantea.

Occurrence.—In a cream-coloured limestone, no Nummulites
being distinguishable with an ordinary lens.

Locality.—Mersa Susa.

Vasum cf. FREQUENS (Mayer-Eymar). (Pl. XLVI, fig. 9.)

Haig ee Mayer-Eymar, Journ. Conchyl. [Paris] 1895, vol. xlii,

Pasion fr ues Cossmann, Bull. Inst. Egyptien, 1901, ser. 4, no. 1, pl. i, fig. 7

Punbonclia frequens Oppenheim, Paleontographica, 1906, vol. xxx, pt. 3, No. 2,
pl. xxiv, figs. 1-7 & p. 318.

Remarks.—tThis form is represented by a very rough limestone-
cast in which the maximum width of the summit region is greater
than the entire length of the shell. The earliest whorls are lost,
but what is preserved of the spiral region shows it to be of a
depressed character. The front aspect of the specimen is, however,
important, as it possesses a well-inflated columellar surface on
which can be traced three or four distant, obscure, nearly horizontal
plications; the outer lip-margin is well rounded, and encloses a
fairly open aperture of equal width throughout. The actual base
is wanting, although, judging from the general contour, the canal
would have been short and insignificant ; the remains of a large
spinose tubercle are present on the periphery.

Dimensions.—Length=65 mm.; width (maximum)=82 mm.

The specimen is evidently related to Yurbinella frequens, de-
scribed by Mayer-Eymar, which has since been well figured both
by M. Cossmann and Dr. Oppenheim, the latter regarding it as
occurring throughout the Mokattam Beds of Kgypt, and even
doubtfully suggesting that it is found in the Nummulites-inter-
medius (=Priabonian) Beds in the neighbourhood of Siwa in the
same country. The species is at present restricted to Egypt.

Occurrence.—It occurs in a yellowish limestone containing
Nummulites, Iithothamnion, and other organisms.

Locality.—Camp at Messa.

1 Ann. Soc. Malacol. Belg. vol. xiii (1878) PP- 41-42 & pls. iii, iv, vii, viii.

2 ¢Deser. Animaux Foss. Nummulit. Inde’ vol. ii (1854) p. 329 & pl. XXxlii,
figs. 4-44.

642 MR. RB. B. NEWION ON [Nov. 1911,

Pelecypoda.
Ostrea cf. VENTILABRUM Goldfuss. (Pl. XLV, figs. 9-11.)

Ostrea ventilabrum Goldfuss, ‘ Petrefacta Germanie’ 1833, vol. ii, pl. Ixxvi,
figs. 4-4.¢ & p. 18.

Ostrea pronaS. V. Wood=ventilabrum 8. V. Wood, Monogr. Pal. Soc. 1861 &
1871, pl. iu, fig. 3 & pp. 29, 181 (Index). [Eocene Mollusca. |

Ostrea ventilabrum A. von Keenen, ‘ Norddeutsche Unter-Oligocain Mollusken-
Fauna’ Abhandl. Geol. Specialkarte Preussen, 1893, vol. x, pt. 5, pl. lxiv,
figs. 5-8 & p. 1011; Rovereto, Atti R. Univ. Genova, 1900, vol. xv, p. 48;
Blanckenhorn, Zeitschr. Deutsch. Geol. Gesellsch. 1900, vol. lii, p. 459.

Remarks.—This form is represented by a number of valves,
the lower being of crescentic contour while the upper is more or
less oblong. The lower valves are also fairly thick and arched,
sometimes more spreading and depressed, and ornamented with
numerous regular stout and radiating coste which in their descent
from the umbonal area are often dichotomized. The periodical
growth-lines of the upper valve consist of irregularly spaced
concentric ridges, the central area of the same valve being well
elevated above a somewhat depressed ventral region. Both valves
exhibit a slightly concave or nearly straight anterior margin.
The umbones show a forward inelination, but are not exogyri-
form; while the adductor-sear impression is extensive and antero-
ventral.

Dimensions in miJlimetres (of adult valves belonging to
different individuals) :—

Lower valve. Upper valve.

LEEDS eae eee 30 40
HVGION Gs suis, do, same O38 65 (approximate).
JONG Hat Velnes Oe aR ane 25 15

Among oysters. exhibiting similar relationships may be men-
tioned O. fimbrioides of Rolle, from the Austrian Oligocene,}
O. cyathula of Lamarek, var. fimbriata Hoernes, which Mayer-
Kymar doubtfully recognized from fragments in the Lower Oligo-
cene (Tongrian) of Egypt,’ besides O. ventilabrum and O. fimbriata,
both scheduled by Dr. Blanckenhorn from similar deposits of the
same country. The true O. ventilabrum is therefore characteristic
of Lower Oligocene deposits, and is known trom England, Germany,
Austria, Northern Italy, and Egypt.

Occurrence.—The valves are considerably worn, and mostly
associated with a cream-coloured limestone weathering to a reddish
colour, containing numerous Nummulites.

Localities.—South-west of Merj ; east of the shrine of Sidi
Mahomet Mahridi, east of Slonta; Old Cistern, east of Slonta ;
north of Slonta; Roman Fort, north-west of Slonta.

1 Sitz. K. Akad. Wissensch. Wien, vol. xxxv (1859) p. 204 & pl. ii, figs. 1-3.
? Bull. Inst. Egyptien, 1896, ser. 3, no, 6, p. 94.

Vol. 67.] KAINOZOIC MOLLUSCA FROM,CYRENAICA, 643

Pxcten arcuatus (Brocchi). (Pl. XLVI, tigs. 3-6.)

Ostrea arcuata Brocchi, ‘Conchiologia Fossile Subapennina’ 1814, vol. ii,
pl. xiv, fig. 11 & p. 578.

Pecten michelotii D’Archiac, Mém. Soc. Géol. France, 1850, ser. 2, vol. iii, pt. 2,
pl. xii, figs. 20-21 & p. 435. =

Janira fallax & deperdita Michelotti, ‘Etudes sur le Miocéne Inférieur de
V Italie Septentrionale’ [Mem. Soc. Holl. Sci. Haarlem] 1861, pl. ix, figs. 4-7

& pp. 78-79.

Pecten michelottii Schauroth, ‘ Verzeichniss Versteinerungen, &c.’ 1865, pl. xvi,
fig. 3 & p. 201.

Cardium pereziforme Schauroth, ibid. pl. xviii, fig. 9 & p. 209.

Pecten arcuatus Fuchs, Denkschr. K. Akad. Wissensch. Wien, 1870, vol. xxx,
pl. x, figs. 388-40 & p. 203. _

Janira michelottii Hermite, ‘Ktudes géologiques sur les Iles Baléares (Majorque
& Minorque)’ [Théses Faculté Sci. Paris] 1879, p. 223.

Cardium subtenuisuleatum Abich non Nyst, ‘Geol. Forsch. in d. Kaukas.
Landern: Geologie des Armenischen Hochlandes’ 1882, pl. vi, fig. 8 &

p. 296.
Pecten nucalis Locard, ‘ Explorat. Scient. Tunisie: Descr. Moll. Tert. Inf.’

1889, pl. x, fig. 2 & p. 51.
Pecten subtripartitus Locard, ibid. pl. x, figs. 4 b-4e & p. 52 (won D’Archiac).
Pecten arcuatus De Gregorio, Ann. Géol. Paléont. [Palermo] 1894, pt. 13, pl. iv,
figs. 83-85 & p. 24; Sacco, ‘ Moll. Terr. Terz. Piemonte’ 1897, pt. 24, pl. xxi,
figs. 14-30 (and varieties, figs. 31-36) & pp. 65-67.
Pecten (Janira) arcuata Oppenheim, Paleontographica, 1900, vol. xlvii, p. 135.
Pecten arcuatus F. Oswald, ‘ Geology of Armenia’ 1906, p. 427.

Remarks.—Some well-marked remains of this species form
part of this collection, the lower or convex valve being that most
frequently preserved. This exhibits from twenty to twenty-two
cost, which are rounded, smooth at the summits, strongly curved
in their descent from the umbonal region, thus producing well-
excavated outer lateral margins, and separated by sulcations which
are about half the width of the ribs. both valves possess eyui-
distant transverse striations within the grooves which apparently
never extend over the summits of the coste.

There is only one fairly good example of an upper valve, from
near Bint, which shows most of the details of costal structure
previously referred to. It is besides very depressed, although
exhibiting a slightly concave surface. The auricles are small in
all specimens, and mostly obscure. ‘I'he specimens vary slightly
in size, the largest example of a lower valve giving the following

Dimensions (large lower valve):—Length=34 millimetres;

ight=37 mm.; diameter=16 mm. :

This Pecten is characteristic of the Uppermost Hocene, or that
part of the Lower Oligocene Beds which is regarded by Oppenheim
and others as Priabonian. According to Prof. Sacco, the original
locality of P. arcuatus should be Rocchetta Cairo of the Savona
district of Liguria, where Oligocene strata are known, and not
Rocchetta, near Asti, as given by Brocchi, where only Plocene Beds
are exposed. There are many other localities for this species in
Northern Italy. It has also been recorded trom Armenia, the
Balearic Islands (Majorca), Biarritz, Algeria, and Tunisia. So far
as Egypt is concerned, we have only a doubtful reference to its
occurrence in that country made by Mayer-Eymar,’ to the effect

1 Bull. Inst. Egyptien, ser. 3, no. 6 (1896) p. 94.

644 MR. R. Be NEWTON ON [Nov. 1911,

that he had seen some indeterminable fragments resembling Ostrea
cyathula var. fimbriata, and Pecten (Neithea) arcuatus, both forms
characteristic of the Lower Tongrian, about 10 miles west of Cairo,
at Kum el Kashab, an area where the fossil trees occur.

Occurrence.—Some of the specimens are associated with a
cream-coloured, more or less compact, limestone weathering reddish-
brown; the example from Messa is in a yellowish, sandy-looking,
caleareous matrix; and another from near Bint, east of Derna, is
found in a rather fragmental limestone varying from reddish brown
to somewhat of a straw-colour. All the matrices contain an
abundance of Nwmmulites.

Localities —After Merj, the plateau to the south-west; wells
at Mer}; near Slonta; east of Slonta; Messa; Kuff Narbea, north
of Wadi Firyah; Mersa Susa; near Bint, east of Derna.

JMQuIPECTEN cf. pELETUS (Michelotti).

Pecten deletus Michelotti, ‘Etudes sur la Miocéne Inférieur de l’ItaliefSepten-
trionale’ 1861 [Mem. Soc. Holl. Sci. Haarlem], pl. ix, figs. 1-3 & p. 77.

Aiquipecten deletus and varieties, ‘Sacco, Moll. Terr. Terz. Pienbitee 1SSi7;
pt. 24, pl. vi, figs. 1-7 & p. 19.

Remarks.—A single valve in the matrix showing ont the basal
area is, on account of the structure of the cost, thought to be
related to P. deletus of Michelotti, from the Tongrian of Northern
Italy. These coste, of which about eight are preserved in the
specimen, are fairly broad, rounded, and furnished with somewhat
coarse annulations ; they are separated by deep sulcations of equal
width with the costz, the interiors of which are ornamented with
four or five longitudinal rows of minute granulations.

Ocecurrence.—The specimen is associated with a cream-
coloured limestone made up of Lithothannion, Nummulites, etc.

Locality.—Derna.

ASQUIPECTEN CYRENAICUS, sp. nov. (Pl. XLVI, figs. 1 & 2.)

Description (lower or right valve).—Shell fan-shaped, inequi-
lateral, shallow, covered with about eighteen straight radial cost,
medially angulate, laterally oblique, aud divided by widely open
V-shaped furrows; grooves and ribs ornamented with narrow,
closely-set, equally-banded annulations, which show a thickening
or tuberculation on each side at the bases of the sulcations ;
posterior expansion (only partly preserved) with three or four
oblique rows of small contiguous granulations.

Dimensions :—Length=55 mm. ; height (about) =50 mm.

Remarks.—The suborbicular or fan-shaped contour of this valve
would associate it with the P.-opercularis type of pectinoid shells,
and therefore it should be regarded as belonging to Fischer's genus
Aiquipecten. The ornamentation of the coste and furrows is
singularly different from that seen in other forms of this genus.
There are no striations radiating from the umbonal region, the
sculpture being entirely composed of the closely-fitting, equally

Vol: 67.| KAINOZOIC MOLLUSCA FROM CYRENAICA. 645

narrow bands which give a regularly-imbricate surface to the
angulate ribs and sulcations.

The specimen is very imperfect in the umbonal direction, and
only a fragment is preserved of the posterior auricle, no part of the
anterior wing being present; a part of the ventral margin is also
fractured.

Probably its nearest ally is a form described and figured by
D’Archiac as Pecten subopercularis, from the Nummulitic deposits
of Bayonne; but in that shell the coste are far more numerous
and, moreover, fine longitudinal striations ornament the grooves,
which are not seen in the present specimen, otherwise the im-
bricating structure of the coste is very similar.’

Occurrence.—tThe specimen is associated with a pinkish lime-
stone full of Nummulites and Lithothamnion, the latter organism
showing out very plainly as smali white, more or less globular
masses. The matrix is entirely different from anything else in the
collection.

Locality.-—Above camp at Ain Sciahat.

VuLsELtA sp. (Pl. XLVI, fig. 7.)

Description (left valve).—Specimen representing an elongate,
narrow valve, the posterior side of which shows a long marginal
curvature extending from the umbonal region ; the lateral margins
were probably more or less parallel, although the anterior one is
absent ; the surface is smooth and slightly convex.

Dimensions :—Length=about 25 mm.; height=55 mm.

Remarks.—tThis valve is very much fractured, but on account
of its lingulate contour it is possibly related to Vulsella crispata of
Paul Fischer, which Dr. Oppenheim identifies from the Vwmmulites-
intermedius Beds of Egypt,” and in lower horizons of the Kocene
of the same country.

Occurrence.—It is attached to a compact cream-coloured
limestone, with a smaller example of the same genus in close
proximity showing concentric laminations. This matrix weathers
to a reddish colour, and contains Nummulites.

Locality.—Base of cliffs, south-east of Mer).

VuuseELia cf, EYMARI Oppenheim.

Vulsella eymari Oppenheim, Paleontographica, 1903, vol. xxx, pt. 3, No.1,
pl. vi, figs. 1-la & p. 74.

Remarks.—External view of a left valve with an eroded
surface, and showing very obscure remains of concentric striation.
It is of oblong form with nearly parallel sides; an antero-dorsal
projection is present indicating an extension of the hinge-region,

‘ Mém. Soe. Géol. France, ser. 2, vol. iii, pt. 2 (1850) p. 436 & pl. xii,
figs. 19-19 a.

2 Palxontographica, vol. xxx, pt. 3 (1903) No. 1, p. 68 & pl. iv, figs. 1-3 & 8,
pl. vi, figs. 12-13 & 15.

646 /- MR. R. B. NEWLON ON [Nov. 1911,

which is succeeded below by a prominent notch or excavation ;
the valve is moderately convex, with gently sloping sides.

Dimensions :—Length=88 millimetres ; height=55 mm.

In contour and size this valve resembles Vulsella eymari of
Dr. Oppenheim, from the Libyan Eocene deposits of Egypt, and its
affinities are probably with that species. If such is the case, then
it must be assumed that the prominent concentric lamin distin-
guishing Oppenheim’s specimen must have disappeared through
weathering or otherwise. Both forms exhibit the anterior projec-
tion of the cardinal area, but the margin below forms more of a
notch in the present shell, than a continuous excavation as in the
example from Egypt. This extension of the hinge-area and the
presence of the notch are apparently not seen in recent examples
ot the genus, and although suggestive of byssal characters, it is
stated in Fischer’s ‘ Manuel’ that Vulsella has no byssal organ.

Occurrence.—A cream-coloured limestone weathering reddish
is the associated matrix ; well-preserved Vummulites are present.

Locality.—East of Slonta.

SPONDYLUS sp.

Remarks.—This specimen is of rather small size, and in a
worn and cracked condition. It possesses both valves in the closed
state, with an imperfect dorsal area showing only the incurved
umbones without indication of hinge-expansions. In general form
haying a greater length than height, it assumes much the contour of
some examples of Sp. rowaulti D’Archiac,’ from the Indian Eocene,
but differs from that species in sculpture by possessing a more
uniform costal system in which the ribs are of one order throughout.
These coste are numerous (about thirty), fine, rounded, and divided
by grooves which, in the ventral direction, are nearly twice their
width, but are much narrower over the umbonal region. On the
summits of the coste there appear to be occasional minute asperities
which, however, are very obscure. No transverse striations are
observable in the sulcations, such as characterize Sp. rouaultt.

Dimensions:—Length = 32 millimetres; height = 27 mm. ;
diameter =15 mm.

Occurrence.—In a cream-coloured marly limestone weathering
to a straw-colour; no Nummutlites distinguishable.

Locality.—North of Slonta.

TRACHYCARDIUM cf. GRANCONENSE Oppenheim.

Cardium (Trachycardium) granconense Oppenheim, Zeitschr. Deutsch. Geol.
Gesellsch. 1896, vol. xlviii, pl. iv, fig. 14 & p. 94, and Paleontographica, 1901,

vol. xlvu, p. 164. .
Remarks.—This form consists of a single left valve in lime-
stone, well inflated, of equal length and height, possessing
numerous coste and grooves which are furnished with a minute

1 <Descr. Anim. Foss. Nummulit. Inde’ vol. ii (1854) p. 272 & pl. xxiv,
figs. 6-8.

—

Vol. 67.] KAINOZOIC MOLLUSCA FROM CYRENAICA. 647

imbricating sculpture strongly resembling that present in Dr.
Oppenheim’s Trachycardium yranconense, a Priabonian species
from the Venetian Alps.

The specimen is much weathered, so that the ornamentation is
strongest in the grooves, and it is only very obscurely and occa-
sionally seen to pass over the ribs themselves, which through
erosion are mostly smooth at the summits.

Dimensions (left valve).—Length= 42 millimetres; height=
(about) 42 mm.; diameter=13 mm.

Occurrence.—In a hard cream-coloured limestone weathering
to a reddish tint and containing Nummulites.

Locality.—Mersa Susa.

Lucina cf. pHaraonis Bellardi.
Lucina pharaonis Bellardi, Mem. R. Accad. Sc. Torino, ser. 2, vol. xv (1854-55)

pl. ii, fig. 12 & p. 190; Oppenheim, Paleontographica, 1903, vol. xxx, pt. 3,
No. 1, pl. xiii, figs. 1-2, pl. xv, fig. 6 & p. 124.

Remarks.—There are several casts of a luciniform shell which
in general aspects show relationship to Bellardi’s L. pharaonis,
from the Mokattam Beds of Egypt. They present the same sub-
orbicular contour; the valves are also fairly well inflated, and
mostly exhibit the postero-dorsal compression as well as a nearly
horizontal antero-dorsal line immediately below the umbones.
Obscure muscular and other markings are seen on the surfaces,
although generally much too indistinct for definition ; occasionally,
concentric striations are preserved. The largest example shows
the following measurements :—

Dimensions (with closed valves):—Length=51 millimetres ;
height=47 mm.; diameter=30 mm.

According to Dr. P. Oppenheim, the species is restricted to Egypt
and Algeria, Coquand’s* L. mevusi from the latter region being now
recognized as the same shell. The species ranges throughout the
Mokattam Beds of Egypt; but, in Algeria, it is said to occur in
the Suessonian stage of the Eocene deposits.

Occurrence.—Specimens mostly in a cream-coloured limestone
weathering to various reddish tints, and sometimes associated with
Nummulites.

Localities.—Top of pass leaving Wadi Khumas; two hours
before reaching the shrine of Sidi Mahomed (before Slonta); Merj
Welis; Kuff Narbea, north of Wadi Firyah.

Luctna cf. NokBAENSIS Oppenheim.

Lucina nokbaensis Oppenheim, Paleontographica, 1903, vol. xxx, pt. 3, No. 1,
pl. x, fig. 13 & p. 189.

Remarks.—The specimen thought to be related to this species

is an internal cast, with united valves of fairly large size and

of moderate convexity. Its contour, however, is rounded, and

1 *Géologie & Paléontologie de la Région Sud de la Province de Con-
stantine’ 1862, p. 269 & pl. xxx, figs, 17-18.

648 MR. R. B. NEWTON ON [Nov. 1911,

approaches more nearly, perhaps, that distinguishing L. pharaonis ;
although the anterior side appears to be more compressed than in
that species, and therefore it resembles Dr. Oppenheim’s type, which
was founded upon an internal cast from the Lower Eocene deposits
of Egypt. The markings on the valves, both pallial and adductor,
are fairly distinct, while parts of the surface exhibit concentric
and radial striations ; moreover, the left valve is minutely pitted, as
shown in Oppenheim’s figure.

Dimensions (with closed valves) :—Length=60 millimetres ;
height=60 mm.; diameter=30 mm.

Occurrence.—Specimen associated with a compact cream-
coloured limestone weathering yellowish or light red, which appears
to contain no Nummulites.

Locality.—Wadi, first camp, west of Derna.

CorBIs LAMELLOSA (Lamarck). (Pl. XLV, figs. 12 & 13.)
Lucina lamellosa Lamarck, Ann. Mus. Hist. Nat. (Paris) 1806 & 1808,
vol. vii, p. 237, & vol. xii, pl. xlii, fig. 3.
Corbis lamellosa Schauroth, ‘ Verzeichniss Versteinerungen ’ 1865, p. 208.
Fimbria lamellosa Frauscher, Denkschr. K. Akad. Wiss. Wien, 1886, vol. i,
coe pes Cossmann, Ann. Soc. Roy. Malacol. Belg. 1887, vol. xxii,
p. 15; Oppenheim, Paleontographica, 1903, vol. xxx, pt. 3, No. 1, p. 152.

Remarks.—The specimen referred to this species exhibits an
external view of a fragmentary valve, attached to the matrix,
having imperfect marginal terminations. It is probably a left
valve—although this is uncertain, on account of the dorsal charac-
ters being very obscure. The sculpture is, however, important, as
it resembles in every way that characterizing this well-known
species. The equidistant, prominently concentric lamine are well
seen, together with the closely-arranged vertical striations which
occur between them.

According to M. Cossmann, this shell ranges through all the
stages of the Kocene formation. Schauroth has determined it
from the Bartonian Beds of Ronca in Northern Italy, Frauscher
has recognized it in the Lower Kocene deposits of the Northern
Alps, while Oppenheim refers to its occurrence in the Mokattam
Beds of Egypt. Corbis pseudolamellosa of the last-named author,’
from the Priabonian formation of Northern Italy, shows also some
striking resemblances to the specimen from Cyrenaica.

Occurrence.—AIn a cream - coloured limestone weathering
reddish, associated with Nummulites.

Locality.—Near Slonta.

Macrra cf. FoURTAUI Cossmann.

Mactra fourtaui Cossmann, Bull. Inst. Egyptien, 1901, p. 184 & pl. iii, figs. 18,
20; Oppenheim, Paleontographica, 1906, vol. xxx, pt. 3, No. 2, p. 189 &
Diexixe piesa —S:

Remarks.—This specimen, although only a cast, has much the

1 P. Oppenheim, ‘ Rivista Italiana di Paleontologia’ vol. vi (1900) p. 32 &
pl. i, figs. 3-3 a.

Vol. 67.] KAINOZOIC MOLLUSCA FROM CYRENAICA. 649

contour of Cossmann’s M. fourtaui from the Upper Mokattam
Beds of the Fayim. It represents a left valve with a nearly
median umbo, and a prominent lunuloid cavity followed by a sub-
rostration. From being a cast the surface is quite smooth, and
therefore the concentric striations which characterize the original
specimens and the further example figured by Dr. Oppenheim are
absent.

Dimensions (left valve).—Length=40 mm.; height=30 mm.

Occurrence.—In a pale marly limestone with Nummulites.

Locality.—Near top of pass leaving Wadi Khumas.

CaRDITA sp.

Remarks.—Specimen represented by a fragmentary natural
cast in the matrix, exhibiting a portion of rather more than a dozen
coste belonging to a right valve. These coste are well-elevated,
narrow, equidistantly separated by deep channels which are of
similar width to the ribs. Although no ornamentation is pre-
served, the costal system somewhat resembles that seen in C. acuti-
costata of Lamarck, from the Middle and Upper Eocene of France ;
but that shell has the summits of its coste furnished with minute
spimose serrations, which are now either lost or were never present
in the fragment from Cyrenaica. Only costal characters are seen,
neither umbonal nor other details of the shell being preserved.

Occurrence.—The specimen is associated with another pele-
cypod cast, nummulites, etc., in a cream-coloured marly rock,
weathering light brown.

Locality.—Top of pass leaving Wadi Khumas.

VI. Luverray.

The Lutetian formation and its fauna are so well known in
Northern African countries, that it is needless to go into particulars
respecting their history, and it is only necessary to refer the
student to the Memoirs that have been issued by the officers of the
Geological Survey of Egypt (Messrs. Beadnell, Hume, Barron, Ball,
and others) for the last ten years, or to the monograph published
by Dr. Blanckenhorn in 1900,’ for full references to. the chief
literature on this subject.

The solitary shell which comes under this denomination is worth-
less as a specimen ; but its matrix contains an important organism
which enables us to determine the presence of Lutetian or Middle
Eocene rocks in Cyrenaica.
h.This is one of the giant Nummulites known as gizehensis of
Ehrenberg, but which belongs to the well-known complanatus
type originally described by Lamarck, and is known throughout
the Lutetian areas of Egypt, Palestine, and Syria, besides further
regions of Northern Africa, and other Mediterranean countries

1 Zeitschr. Deutsch. Geol. Gesellsch. vol. lii (1900) pp. 403-79.

650 MR. R. B. NEWION ON [ Nov. 1roEr

such as Spain, Italy, ., aS well as Crete, where these large
Ni urna were ice ago Soares mined by D’ Archiac.

The matrix containing this nummulite and oyster is much more
compact than the sandy-looking rock that contains the pectini-
form shells—regarded as of Aquitanian age: both deposits being
similarly localized yet furnishing panied of different horizons,
Ain Sciahat being the neighbourhood referred to.

Pelecypoda.
OstREA sp. indet.

Remarks.—the specimen is a fragmentary oblong, smooth and
moderately convex valve, embedded in matrix, which has ap-
parently lost, through erosion or otherwise, its external layers. so
that only the polished surface of the inner structure of the shell is
now exposed. It is not possible, therefore, to identify such a
fossil, but from its general shape and very slight curvature of the
postero-dorsal region, it might have belonged to such a form as
Solander’s Ostrea gigantea, aehtich is distributed throughout the
Eocene rocks.

Dimensions (approximate).—Length=60 millimetres; height

Occurrence.—The matrix is a cream-coloured limestone con-
taining Nummulites gizehensis.

Locality.—Plateau above Ain Sciahat.

VIL. Resvtts.

The fossil shell-remains from Cyrenaica prove the presence of
post-Pliocene, Miocene (Vindobonian and Aquitanian), Oligocene
or Uppermost Eocene (Priabonian), and Middle Eocene (Lutetian).

The post-Pliocene fauna is similar to what is known in other
North African or Mediterranean countries, the presence of Cerasto-
derma edule in rocks situated some distance from the sea-board in
a solid limestone suggesting a more ancient facies than those
occurring in an actual beach-deposit nearer the sea.

Such mollusea as Strombus ct. coronatus, Alectryonia cf. virleti
constitute reliable evidence in favour of the Helvetian-Tortonian
(Miocene) deposits being present in Cyrenaica, and forming part of
similar beds occurring in Egypt and other neighbouring countries.
The genera Amphisteqgina and Lithothamnion also occur in these
rocks.

The abundant pectinoid shells found at Ain Sciahat with highly
ornamented costa, as well as the simpler forms found at Birlibah
and Wadi Umzigga, favour an Aquitanian horizon, more especially
as specimens from the last-named locality exhibit examples of
Lepidocyclina elephantina, which is characteristic of Aquitanian
deposits.

1 See V. Raulin, ‘Note sur la Constitution Géologique de l'Ile de Créte’
Bull. Soe: Géol. France, ser. 2, vol. xiii (1856) pp. 439-58.

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NOZOIC MOLLUSCA FROM CYRENAICA.

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Wol.;67.| KAINOZOIC MOLLUSCA FROM CYRENAICA. 651

The occurrence of Pecten arcuatus and other associated mollusca
would suggest the presence of the Priabonian horizon.

The late Prof. Rupert Jones’s remark that the specimen of Num-
mulites perforata from Mersa Susa, one of the localities yielding
Pecten arcuatus of the present collection, was found in rocks which
were considered to be younger than the Nummulitic beds of Crete,
the latter being regarded as of Lutetian or Middle Eocene age,
is curious confirmation of the present results, the molluscan
evidence now determining the Priabonian horizon for these particular
deposits.

The presence of Lutetian or Middle Eocene beds in Cyrenaica
seems also to be substantiated by the occurrence of the large
gizehensis type of Nummulhtes found associated in the matrix with
an indeterminable Ostrea.

A collection of well-preserved echinoids was also obtained from
the various formations in Cyrenaica, and they have been studied
by Prof. Gregory, with the general conclusion that their horizons
agree with those now suggested for the Mollusca.

EXPLANATION OF PLATES XLITI-XLVI.

{Except where otherwise specified, the figures are drawn of the natural size. |

Prare XLITI.
Hygromia sordulenta (Morelet).
Post-Pliocene (recent beds). Bonmansur, south of Derna. (See p. 619.)
Fig. 1. The upper or spiral view. x 2.
2. Profile of the same specimen. X 2.
Helicella tuberculosa (Conrad).
Post-Pliocene (recent beds). Plain east of Benghazi. (See p. 620.)
Fig. 3. Dorsal aspect of the largest specimen.
4, Front view of the same.
5. Sculpture as seen on the penultimate whorl. x 3.
Cerastoderma edule (Linnzeus).
Post-Pliocene (recent beds). Benghazi. (See p. 621.)
Fig. 6. External view of a left valve.

Jagowia pecten (Lamarck),
Post-Pliocene (recent beds). Benghazi. (See p. 622.)
Fig. 7. External view ofa left valve. x 3.
8. Sculpture details of the same. X 6.
Cerastoderma edule (Linneeus).
Post-Pliocene (ancient beds). Plain east of Benghazi. (See p. 623.)

Fig. 9. Left lateral view of a specimen covered anteriorly by a limestone
which is superficially pitted with minute rounded contiguous
excavations of probably organic origin.

10. Posterior end or ‘ escutcheon view’ of the same specimen.

Qo 3. G..S: No; 268, ay

652 MR. R. B. NEWLON ON [Nov. 1911,

Alectryonia cf. plicatula (Gmelin).
Miocene (Helvetian-Tortonian). Gubah. (See p. 626.)

Fig. 11. External view of a lower valve, showing the tubular character of
the plications.

Anadara cf. turonica (Dujardin).
Miocene (Helvetian-Tortonian). From Merj Plain to Wadi Hamema.

Fig. 12. Outer aspect of a left valve. :
13. Surface-structure. xX 3. | See p. 628.

Strombus cf. coronatus Defrance.
Miocene (Helvetian-Tortonian). Gubah.
Fig. 14. Dorsal view of natural cast. (See p. 626.)

PuateE XLIV.

Ostrea cf. caudata Minster. (See p. 629.)
Miocene (Aquitanian). East of shrine of Sidi Mahomet Mahridi,
east of Slonta.
Fig. 1. External view of a lower valve, showing attachment-surface.

Spondylus cisalpinus Brongniart. :
Miocene (Aquitanian). Ain Sciahat (above camp). (See p. 630.)
Fig. 2, External view of specimen, showing the surface of the larger valve.

Oopecten rotundatus (Lamavck).
Miocene (Aquitanian). Wadi Umzigga. (See p. 634.)
Fig. 3. External view of a valve with an imperfect apical region.

Aiquipecten ct. pasinii (Meneghini).
Miocene (Aquitanian). Ain Sciahat (above camp). (See p. 632.)
Fig. 4. Outer view of a left valve.
5. Portion showing details of sculpture. x 3.

Aiquipecten hauert (Michelotti).
Miocene (Aquitanian). Birlibah. (See p. 634.)
Fig. 6. External view of a fragmentary valve.

PuatE XLV.
Ostrea crassicostata G. B. Sowerby. (See p. 630.)

Miocene (Aquitanian). East of shrine of Sidi Mahomet Mahridi,
east of Slonta.

Fig. 1. External view of a lower valve, half the natural size.
2. Inner view of same specimen, half the natural size.

Pecten vezzanensis Oppenheim.
Miocene (Aquitanian). Ain Sciahat. (See p. 631.)
Fig. 3. External view of specimen.
4, Sculpture details of the same. X 3.

Aiquipecten camaretensis (Fontannes). (See p. 633.)
Miocene (Aquitanian). Fountain of Apollo, Cyrene. [B.M.—L 16341.]
Fig. 5. View of a well-preserved valve.
6. Sculpture details of the same. X 5.

Wol."67, | KAINOZOIC MOLLUSCA FROM CYRENAICA. 653

Aiquipecten zitteli (Fuchs).
Miocene (Aquitanian). Ain Sciahat. (See p. 632.)
Fig. 7. External view of a specimen.
8. Sculpture details of the same. x 4.

Ostrea ventilabrum Goldfuss.

Oligocene or Kocene (Priabonian). Near Slonta. (See p. 642.)

Fig. 9. A spreading and depressed form of a lower valve.
10. Another specimen, showing a more arcuate character.
11, An upper valve belonging to a small specimen.

Corbis lamellosa (Lamarck).

Oligocene or Hocene (Priabonian). Near Slonta. (See p. 648.)

Fig. 12. External view of a fragmentary valve.
13. Sculpture of the same specimen, showing the characteristic vertical
costze between the concentric ribs. x 3.

Pratt XLVI.
Aiquipecten cyrenaicus, sp. nov.

Oligocene or Hocene (Priabonian). Ain Sciahat (above camp). (See p. 644.)

Fig. 1. External view of a specimen representing a lower or right valve,
showing the V-shaped furrows.
2. Sculpture details of the same. X 3.

Pecten arcuatus (Brocchi).

Oligocene or Eocene (Priabonian). Messa, and near Bint. (See p. 643.)

Fig. 3. Outer aspect of a fragmentary lower valve from Messa.
4. Profile of the same, showing convexity.
5. Sculpture details of the same specimen. X 3.
6. External view of an upper valve of another specimen, from near
Bint.

Vulsella sp.

Oligocene or Eocene (Priabonian). South-east of Merj. (See p. 645.)
Fig. 7. Valve of lingulate contour, resembling V. crispata Fischer.

Gisortia gigantea (Minster).
Oligocene or Hocene (Priabonian). Mersa Susa. (See p. 640.)
Fig. 8. Front aspect of a small form in the condition of a natural cast.

Vasum cf. frequens (Mayer-Eymar).

Oligocene or Hocene (Priabonian). Messa. (See p. 641.)
Fig. 9. Front aspect of a specimen (natural cast), showing traces of
columellar plications. Reduced to half the natural size.
Rostellaria sp.

Oligocene or Eocene (Priabonian). South-east of Messa. (See p. 640.)
Fig. 10. Dorsal view of a limestone cast.

Euspira cf. possagnensis Oppenheim.

Oligocene or Eocene (Priabonian). Hast of Ain Hafra. (See p. 638.)

Fig. 11. Dorsal view of a natural cast, showing the extensive basal whorl,
Reduced to half the natural size.

Dy S0 os

654 MR. F. CHAPMAN ON KAINOZOIC [Nov. 1911,

(C) ForaminiFera, Ostracopa, and Parasitic Foner from the
Kartnozorc Limestones of Crrunaica. By FREpERIcK CHAPMAN,

A.L.S., F.B.M.S.

Tuer following report is based on specimens collected by Prof. J.
W. Gregory in Cyrenaica. The principal localities whence the
samples came are Derna on the coast, a camp about 5 miles west of
Derna, and Ain Sciahat, the site of the ancient city of Cyrene,
which is about 2000 feet above sea-level. The specimens range in
age from Middle or Lower Eocene to Pleistocene.

Previous Literature.

The only necessary reference to literature is the following extract
from the late Prof. T. Rupert Jones’s ‘Catalogue of Fossil Fora-
minifera in the British Museum’ (1882, p. 45) :—

‘ Nummulites perforata. Marsa Susa, the ancient port of Cyrene. From

strata younger than the Nummulitic bed of Crete referred to further on
[p. 48]. Collected by Admiral Spratt.’

Details of the Rock-Samples.

Derna.

The specimens from Derna include a consolidated beach-sand with
some molluscan shells. This rock is mainly composed of smail
rolled shell-fragments, which have been cemented by carbonate of
lime into a fairly coherent rock.

Horizon.—Pleistocene.

Two specimens collected from the Wadi Derna near the town are
pink or cream-coloured nummulitic limestones, having the num-
mulites exquisitely preserved, and showing the structure in median
sections in a most striking manner. Most of the chambers of these
discoidal foraminifera are empty, and the septation is thus clearly
shown up to the centre of the test. These nummulites vary from
1:5 to 4 millimetres in diameter. The surface is distinctly striate.
The central chamber is a megasphere, and in full-sized individuals
there are about five whorls of chambers. They all belong to UX.
(Paronia) curvispira Meneghini, a companion-form to the large
microspheric Nummulites gizehensis Ehrenberg.

Horizon.— Middle Kocene.

‘Derna’ (No. 178). A large test of Nummulites gizehensis Ebr.
measuring 5°8 cm. in diameter and 7 mm. in greatest thickness.
Some limestone-matrix attached to the specimen carries a few tests
of NV. rouault. dArch., a form closely allied to WV. curvispira, but
distinguished by its sharp periphery and greater umbilical axis.

Horizon.—Middle Hocene.

Werna’ “(Noss 177, 1 79>ne1). Nummulitic limestones with
NV. gizehensis Khr., NV. curvispira Menegh., and NV. rowault: d’Arch.
H orizon.—Mniddle Eocene.

ee ee

Wol-' 67. |

‘Ain Seghia— Wadi Derna’ (No. 22).

FORAMINIFERA, ETC. FROM CYRENAICA. 655

A pink limestone with

large and well-preserved individuals of Vummulites chrenbergi De

la Harpe, and NV. curvispira Menegh.

©) centimetres in diameter.
Horizon.—Middle Eocene.

The former measures nearly

‘Foraminiferal limestone about 340 feet above sea-level, above
Bint, east of Derna’ (No. 25). A pale yellowish limestone, somewhat
friable, containing numerous small organisms, chiefly foraminifera.
A crushed sample yielded the following species :—

Miliolina contorta (dOrb.).
specimens.

MM. lucens Schwager. Numerous.

M. ferussaci (dOrb.). One minute
example with few, neat coils.

Polymorphina compressa d’Orb.

Truncatulina culter (P. & J.).

Tr. lobatula (W. & J.).

Several |

near Cairo, by Schwager, under the
name of Pulvinulina mokattamensis.
Anomalina ammonoides (Reuss).
A. insecta Schwager.
Pulvinulina repanda (¥. & M.).
P. elegans (V’Orb.).
Polystomella striatopunctata (F. & M.).
Operculina libyca Schwager.

Nummulites curvispira Menegh.

Tr. ungeriana (d’Orb.). Recorded from
the Middle Eocene (Mokattam Marl),

Horizon.—Middle Eocene.

‘Wadi Nagr, first camp west of Derna’ (No. 39). A white, some-
what chalky limestone, containing abundant, more or less frag-
mentary tests of Orthophragmina pratti (Mich.) [see Notes, p. 659].
Operculina and Nummulites, with numerous echinoid-fragments,
are also present.

Horizon.—Bartonian (Upper Eocene) or Lutetian (Middle

Kocene).

‘Slope above Camp at Wadi Nagr, Derna’ (No. 44). <A pink
limestone, composed of Lithothamnion and foraminifera. In thin
section this rock is seen to consist of numerous fragments of a
thick shrubby Lithothamnion, with an equal proportion ef tests of
nummulites, chiefly VV. curvispira ; also tests of smaller foraminifera
such as 7’rwncatulina, and fragments of echinoid-tests and spines,
embedded in a subcrystalline matrix. The pieces of Lithothamnion
are invariably more or less crowded with small, stout, rhombic
dolomite-crystals, often showing a dark centre and zonal structure.

Horizon.—Middle Eocene.

Wadi Umzigga.

‘Limestone with Oopecten; Wadi Umzigga’ (No. 41). A
weathered limestone-fragment consisting almost entirely of the tests
of Lepidocyclina elephantina Munier-Chalmas (see Notes, p. 660).
A few rotaline foraminifera are seen scattered through the matrix,
and also some tubular remains of (?) calcareous alge.

Horizon.—Aquitanian (Lower Miocene) or Stampian (Upper
Oligocene). This horizon is given on the excellent authority of
M. Douville.

656 MR. F. CHAPMAN ON KAINOZOIC [ Nov. 191%

The District of Cyrene.

‘Limestone with echinoid spines, etc.; Sidi Rof Diasiasia,
south-east of Cyrene.’ <A pale cream-coloured limestone weathering
to pink ; composed of echinoid-spines and test-plates, and forami-
nifera, chiefly nummulites. A slender flexuous variety of J.
gizchensis, var. viquesneli De la Harpe, is here common. Also
several specimens of Operculina ef. libyca Schwager.

Horizon.—Lower Hocene to Miocene.

‘Limestone ; coastal plain: west of Mersa Susa’ (No. 92). A
dense, cream-coloured nummulitic limestone weathering to a
reddish colour. The nummulites are beautifully preserved ; they
are chiefly N. gizehensis Ehr. and NV. curvispira Menegh. There
also occurs a very fine median section of a minute nummulite,
NV. subbeaumonti De la Harpe.

Horizon.—Middle Eocene.

‘Foraminiteral limestone, 530 feet above the sea, west of Mersa
Susa’ (No. 95). A dense, cream-coloured limestone, showing
cleavage-surfaces of echinoid-plates and spines. A microscopic
section reveals a purely organic base of minute foraminifera, cal-
ceareous alge, and shell-fragments, through which are scattered
nummulites and echinoid-remains. The nummulites are com-
paratively small, thick, and possess a bluntly rounded periphery.
They are, in all probability, referable to NV. subdiscorbina.

Horizon.——Middle Eocene.

‘ Echinoid-limestone ; 1100 feet above the sea. Platform east of
Ain Hafra’ (No. 98). <A hard, cream-coloured limestone, with
ferruginous weathering and many natural sections of Nummu-
lites subdiscorbina De la Harpe. A similar rock at the level of
1090 feet, north of Cyrene, includes NV. swbramondi De la Harpe.

Horizon.—Middle Eocene.

‘ Fibularia Limestone. Altitude 1215 feet above sea-level. Foot
of Upper Cliff of Cyrene, west of Ain Hafra’ (No. 78). Limestone
with echinoid-remains, and a small species of Nummulites, cf.
N. curvispira.

Horizon.— (?) Middle Hocene.

N. gizehensis var. lyelli, associated with N. curvispira Menegh.,
occurs in specimens Nos. Cy 84, Cy 86, Cy 88, from the Cyrene
escarpment north of Ain Sciahat, at the level of 1560 feet and a
little below that.

Horizon.—Middle Eocene.

‘Marly limestone with Clypeaster. Hast of camp at Ain
Sciahat’ (No. 187).—A calcareous marl, containing numerous tests
of Operculina libyca Schwager. A similar marl from above the
camp at Ain Sciahat (No. 188) is full of Mummulites subramondi
De la Harpe.

Horizon.—Lower Eocene to Miocene.

This specimen also yielded Bolvina textilarioides Reuss, and
Pulvinulina karsten Reuss.

ol. 67. | FORAMINIFERA, ETC, FROM CYRENAICA,. 657

The Slonta District.

‘Nummulitic limestone, about 5 miles north-east of the shrine
of Sidi Mahomet el Homra, east of Slonta.’ A compact lime-
stone variously coloured, from pale cream on the fresh surface, to
reddish brown on the weathered portions. The rock is largely
composed of nummulites, chiefly NW. gizchensis var. pachoi De la
Harpe, and JV. curvispira Meneghini.

Horizon.—Middle Eocene.

‘A brecciated shell-limestone east of Slonta’ (No. 289), with
numerous foraminifera, chiefly NV. subdiscorbina, De la Harpe.
Horizon.—Middle Eocene.

Echinolampas Limestone (No. 290), north of the Roman Castle,
north-west of Slonta, and an iron-stained limestone (No. 288),
east of Slonta, are both chiefly composed of Nummulites gizehensis
var. lyelli and NV. curvispira.

Horizon.—Middle Eocene.

Messa and Wadi Jeraib.

‘A yellow limestone (No. 239), with Pecten arcuatus,’ Messa, is
composed of asmall lenticular nummulite. Theformand arrangement
of the septa, the number of whorls, and the shape and size of the
small central chamber, all point to the species as belonging to
thé ‘planulata’ group. Dela Harpe regarded Lamarck’s species
N. planulata as divisible into WN. planulata sensu stricto and
NV. elegans Sow., and made a third species, V. fraasz, distinguished
by its smaller size as compared with the typical microspheric
NV. planulata: in that feature it also resembles the megalospheric
shell of WV. elegans. The present form may, therefore, be regarded as
a moderately small variety of De la Harpe’s WV. fraast. The typical
examples of the latter occur in Egypt, according to De la Harpe,’
in the Libyan Stage (Lower Eocene) of El Guss Abu Said, west of
Farafrah. In the Nummulitic series of Sinai, from a bed referred
either to Middle or to Upper Eocene, I have recorded undoubted
examples of V. planulata.? It is, therefore, possible that the small
variety from Messa is one of the remnant of the planulata type,
which ranged upwards as far as the Bartonian. The Cyrenean
. Specimens average 2 millimetres in diameter, and show four to five
whorls in transverse section; they have about six chambers in a
quadrant on the fourth whorl.

‘Limestone. Gasr el Migdum’ (No. 189).—A hard, compact,
whitish limestone, crowded with well-preserved tests of Nummulates
beaumonte D’ Archiac.

Horizon.—Middle Eocene.

1 Palzontographica, vol. xxx, pt. 1 (1883) p. 162 [8].
2 Geol. Mag. dee. 4, vol. vii (1900) pp. 367-68.

658 MR. F. CHAPMAN ON KAINOZOIC [Nov. rg11,

The District near Merj.

‘Limestone south-west of Bigratah, north-east of Merj ’
(No. 140). This specimen has been discoloured to an ashen grey.
The weathered surface is ironstained, and shows numerous sections
of Nummulites gizehensis and N. curvispira.

Horizon.—Middle Eocene.

‘Nummulitic limestone, north-eastern end of the Mer] plain’”—
A dense cream-coloured limestone, weathering to a ferruginous red.
The weathered surface shows etched tests of NV. gizehensis (typica).

Horizon.—Middle Eocene.

‘Limestone with Hchinolampas. Wells at Merj’ (No. 184),—
Two specimens of a nummulitic limestone which is red on the
weathered surface. Containing tests of Nummulites gizehensis var.
lyelli and V. curvispira.

Horizon.-—Middle Hocene.

‘Nummulitic limestone at the top of the plateau-scarp, south-east
of Merj’ (No. 164). A dense, white nummulitic limestone, showing
cleavage-surfaces of echinoid-plates on the fractured faces of the
rock. In microscope-section the rock is seen to be partly re-
crystallized, the matrix being finely crystalline, and the cavities
of the organisms in part filled with larger crystals of calcite.
Organisms rather obscure. ‘lhe following genera of foraminifera
are present :—Srgmoilina, Alveolina, Anomalina, and Nummulites.

‘Oolitic limestone. Altitude 440 feet above sea-level, on the scarp
west of Ptolemeta’ (No. 156).—A loosely consolidated beach- or
dune-sand, consisting of rolled fragments of shells, Zcthothamnion
and foraminifera (Milioline of the M. trigonula and other shallow-
water types), cemented together by a thin layer of calcareous
material. All the fragmentary constituents are calcareous and of
organic origin, and are. bored in all directions by a perforating
organism. This rock resembles the Kathiawar building-stone.’

East of Benghazi.

‘Limestone. Plain east of Benghazi’ (No.188). An extremely
hard, fine-grained limestone, containing shells of gasteropods
entirely recrystallized. Under the microscope this rock is seen to
be a fine calcareous mud containing echinoid-spines, and forami-
nifera (Dentalina and Globigerina). The rock is brecciated, and
in one fragment is a cluster of radiolarian tests, rather poorly
preserved. A specimen (No. 185) from an adjacent locality is
largely composed of fragments of Lithothamnion, and is in part.
dolomitized.

1 See Q. J. G. &. vol. 1vi (1900) pl. xxxii, fig. 2.

Vol. 67.] FORAMINIFERA, ETC. FROM CYRENAICA. 659

Notes on the Fossils.

Parasitic (?) Fungi.
PAL#ACHLYA Sp.

The tests of Lepidocyclina elephantina Munier-Chalmas, which
form the bulk of rock-specimen No. 41 from Wadi Umzigga, are
seen in thin section under a high power to be in parts permeated
by a perforating fungus, which closely resembles Palcachlya
perforans Duncan.’ The spores are 17 in diameter, consisting of
a dark-brown nucleus and a transparent, yellowish investment, and
they are roughly spherical. They run in strings of six or more,
crossing one another, and so forming anopen network. The thread-
like hyphez form a densely-matted structure, occurring 1 patches
through much of the test-wall of the foraminifer. ‘These spores
remind one of many similar occurrences in the tests of Tertiary
foraminifera, noted by Carter and others. The brown colour of the
nucleus is probably the result of the reaction of organic agencies,
such as ulmic acid, on the iron of the accompanying sediments.

Foraminifera.

NUMMULITES CURVISPIRA Meneghini, var. MAJoR, nov.

The nummulites in specimen No. 88, referable to V. curvisprra,
possess an extraordinarily large megasphere. Its usual diameter
in that species and in the related JV. tchihatcheffi D’ Arch. is about
1mm. Our specimens further differ from NV. tchihatcheffi, which
has a rounded periphery, by being sub-acute on the margins,

The diameter of the megasphere in the variety major is 1-75 mm.

ORTHOPHRAGMINA PRATTI (Michelin).

Orbitolites prattii Michelin, 1846, ‘Iconographie Zoophyt.’ p. 278 & pl. Ixin,
fig. 14.

Orbitolites fortisii D’Archiac, 1850, Mém. Soc. Géol. France, ser. 2, vol. in,
p. 404 & pl. viu, figs. 10-12.

Orbitoides (Discocyclina) papyracea Giimbel (non Boubée), 1868, Abhandl. —

K. Bayer. Akad. Wissensch. vol. x, p. 690 & pl. iii, figs. 3-12, 19-29.
Orthophragmina pratti (Michelin) Schlumberger, 1903, Bull. Soc. Géol. France,
ser. 4, vol. iii, p. 274; pl. viii, figs. 1-8, 8-10, pl. ix, fig. 17 & text-figs. a, b.
This is a well-known type of the older or Kocene group ot
Orbitoides, some of the tests in the rock from Derna (No. 39)
having a diameter of 17 mm. They are somewhat flexuose, and
thus bear a certain resemblance to Orthophragmina sella (D’Arch.)
= 0. ephippium (Schlotheim), but are not so remarkably saddle-
shaped as that species. J have not, so far, succeeded in cutting
through the initial series of chambers in the present specimens;
but the thickness of the median series of chambers in vertical

1 Q. J. G. 8. vol. xxxii (1876) p. 205 & pl. xvi.

660 MR. F. CHAPMAN ON KAINOZOIC [Nov. 1911,

section, and the character of the pillars in the outer layer, suffi-
ciently determine the species. The present specimens are only of
moderate dimensions, since D’Archiac recorded this form as having a
diameter as great as 50 mm. The average length of the chambers
in the present examples is ‘125 mm.; width of ditto=-025 mm.

O. pratti occurs typically at Kressenberg (Middle Eocene) and
Biarritz (Upper Eocene).

LEPIDOCYCLINA BLEPHANTINA Munier-Chalmas,

L. elephantina Munier-Chalmas, 1891, ‘ Etude du Tithonique, du Cretacé & du
Tertiaire du Vicentin, Thése de Doctorat’: Paris, pp. 71-77, 90; Prel. Note
(Bull. Soc. Géol. France, ser. 3, vol. xix, p. xxxii). See also P. Lemoine
& R. Douvillé, 1904, Mém. Soc. Géol. France, vol. xii, no. 32, fase. ii, p. 13
& pl. ii, figs. 18, 19.

A limestone (No. 41) from the Wadi Umzigga consists almost
wholly of the agglomerated tests of this species, which is the
largest known Lepidocyclina. It reaches a diameter of 8 to 10 cm.,
according to MM. Lemoine & Douvillé. It is closely allied to
L. dilatata Michelotti, an Aquitanian species which, however, in
the microspheric stage, or form with the larger test, attains a
diameter of only 4 centimetres.

One fragment in a thin section shows a megasphere which
measures about 1°37 mm.in diameter; the thickness of the inter-
mediate area of the test is about 65 mm. On the authority of
Lemoine & R. Douvillé* (1904), Z. elephantina is typical of Aqui-
tanian beds in Italy: while H. Douvillé* holds that the species
is Stampian (Upper Oligocene).

Ostracoda.

LoxocoNCHA CYRENAICA Sp. nov.

Description.—Valves in side view, subquadrate; anterior border
rounded below and_ obliquely

Loxoconcha cyrenaica, truncate above; posterior ex-
5/0. 2OUL) x 70. tremity bluntly acuminate; ven-

tral border sinuous, and convex
in the posterior third; dorsal
border nearly straight. Hdge
view, subtrigonal, thickest in the
posterior third, sloping evenly
towards the anterior edge. Sur-
face of the valves covered with
fine prickles; the sulcus behind

evn ge tobi IRL ITS SENSE DENSE vee
“Hi net
St areas RRC ONE

le the anterior margin is relieved by

a few large pits, with evidence of

[No. 28 from near Bint, east of less conspicuous pits along the
Derna, Middle Eocene. | extreme anterior margin.

Mém. Soc. Géol. France, vol. xii, fase. ii, No. 32, p. 31.
* Bull. Soc. Géol. France, ser. 4, vol. vii (1907) p. 468.

ey ee ae
’

Vol. 67.] FORAMINIFERS, ETC, FROM CYRENATCAs 661
Length = +725 millimetre; height = -4 mm.; thickness of
carapace = °325 mm,

Remarks.—The carapace of this species is somewhat like that

of L. tamarindus (Jones), in outline, viewed from the side; but

the form here described is much thicker posteriorly, and has the
anterior border distinctly acuminate.

Horizon.—Middle Hocene at Wadi Nagr, west of Derna
(No. 33). In a compact subcrystalline limestone, slightly iron-
stained; mainly composed of the large tests of Nummulites gize-
hensis Ehr. (one haying a diameter of 5°5 centimetres), and
LV. curvispira Menegh,

CyrHEre stRiaropuncrata (Romer).

Frequent. A common species in the Middle Eocene of England
and the continent of Europe.
Horizon.—Middle Eocene. Wadi Nagr, west of Derna (on

No. 33).

? CYrHERE WETHERELLI Jones.

One valve in a marly limestone (No. 187), from east of Ain
Sciahat, which contains Operculina libyca Schwager, Bolivina
textilarioides Reuss, and Pulvinulina karstent Reuss. It belongs
doubtfully to the genus Cythere, and resembles Cythere wetherelli
Jones * in many respects, although it is not quite identical. The
latter form is found in the Upper Eocene and Oligocene of Colwell
Bay and the Upper Eocene of Barton. Also in the Antwerp Crag
(Lower Pliocene).

{(D) The Foss1z Ecuinorea of Cyrexaica. By Jon Watrer
Greeory, D.Sc., F.R.S., F.G.S., Professor of Geology in the
University of Glasgow.

[Puates XLVII-XLIX. |

THE specimens were collected during the expedition of which the
geological results have been recorded in the foregoing pages
(572-615). The fossil Echinoidea collected in Cyrenaica during
our journey include ten determinable species represented by over
a hundred specimens. Many of them are imperfect, but were col-
lected on account of the light which they might throw on the
distribution of the species.

I have to express my thanks to Dr. F. A. Bather for having
kindly compared some of the specimens of Echinolampas with
specimens in the British Museum collection, and to M. J. Lambert

1 Cytherideis tamarindus Jones, ‘Monogr. Brit. Tert. Entom.’ (Pal. Soc.)

- 1857, p. 49 & pl. iii, figs. 4a-4; Loxoconcha tamarindus (Jones) G. 8. Brady,

Trans. Linn. Soe. vol. xxvi (1868) p. 455 & pl. xxv. figs. 45-48.
2 Q. J. G. S. vol. x (1854) p 161 & pl. iii, figs. 9a-9 d,

662 PROF, J. W, GREGORY ON [Nov. 1911,

for his careful examination of several of the species, as also for his
valuable notes concerning their affinities.
The list of the chief echinoids collected is as follows :—

Clypeaster biarritzensis Cott., Echinolampas discus Desor.

var. trotteri nov. Hypsoclypeus hemisphericus (Greg.)
Fibularia luciani (Lor,). Hemiaster scille Wright.
Scutetla tenera Laube. Schizaster ederi, sp. nov.
Amphiope duffi, sp. nov. Sarsella lanbertt, sp. nov.
Amphiope sp. | Huspatangus sp.

Echinolampas cherichcrensis Gauth. |

Description of the Species.

CLYPEASTER BIARRITZENSIS Cotteau, 1873, var. TROTTERI nov.!
(Ele DENA fess La &- 1 b,)

Clypeaster biarritzensis Cotteau, 1873, in R. de Bouillé, ‘ Pal. Biarritz,’ p. 10.
{| Not seen. | : ‘

Clypeaster biarritzensis Cotteau, 1891, ‘Ech. Koc., Pal. frang.: Terr. Tert.’
vol. i1, p. 228 & pl. celx.

Clypeaster biarritzensis Flick, 1900, ‘ Priab. en Tunisie’ C. R. Acad. Sci.
Paris, vol. cxxx, p. 149.

Clypeaster biarritzensis Pervinquiére, 1908, ‘Géol. Tunisie-Centrale’ Carte
Géol. Tunisie, p. 199.

Characters.—Form and dimensions similar to those normal to
the species. Petals of ambulacra shorter, the poriferous zones
broader, and the distal ends less open than in the typical form.

| | ; ae
Dimensions in | Cy 96 C.biarritzensis.| C. breunige. C. subpla-
“17: fh | Cy 98. a eremine| ; a Ga cunarius.
millimetres. Cotteau’s fig. Laube’s E. of Fuchs’s type
| ; type. | Siwa, x
Length! 2. ae | 70 66 i Ae 60 OL Ne)
Breadht seen tt) wG7es 59 41 | 50 88 |
Heiehtsn eee een eel 9 | 10°5 al 12
| Length of anterior | | | |
petaly ccc me eee Pah es MOE 21 1S 165 ) eee
Distance trom proximal | | quite fae:
end of anterior petal | | ( thirds of
to anterior margin | Bayaio
Gftest et MA wemenl a4 31 ee: | 242 Jd

Distribution.—Typical form: Upper Hocene ; Lou Cout near
Biarritz. Gebel Batene, Tunisia.

Var. trotteri. In a pale-yellowish marly limestone containing
many specimens of Overculina libyca. alfa mile east of the camp
at Ain Sciahat, Cyrene (Cy 98).

Cy 273. Ain Sciahbat, in a soft marly Operculina Limestone.

' The variety is named after my companion, Dr. J. Trotter, who collected
one of the two specimens.

¥ol..67.] THE FOSSIL ECHINOIDEA OF CYRENAITCA. 663

Affinities.—This Cyrenean Clypeaster agrees so closely in all
characters, except the form and length of the petals, with Cl. b2-
arritzensis, that it seems wiser to leave it in that species, but as a
_ distinct variety.

As Cl. biarritzensis has not been recorded from Egypt, it was
natural first to compare the specimens with the flat Upper Eocene
Clypeaster breunigi of Laube, which agrees in general shape and
has been recorded from the district east of Siwa. C. breunigi is
either a very variable species, or else too many echinoids have been
referred to it. The two specimens from Cyrene differ from Laube’s
type of Cl. breunigi in the absence of the vertical undulation of
the margin of the test ; but that character is not shown in the
specimens from east of Siwa, or from Sta. Giustina near Possagno,
referred to Cl. breunigi by P. de Loriol* and Dr. Oppenheim” re-
spectively. De Loriol’s specimens also differ from Laube’s type
in the character of the petals, which the former described as ‘am
Ende gerundet und weit offen’; and Laube also says that the
petals are ‘vorne weit offen,’ but his figures represent them as
nearly closed. Dr. Oppenheim’s specimen, on the other hand, is a
long oval echinoid, with short and nearly closed petals. It is
only 30 mm. long, and so may be a young form: but he® suggests
that it is a Laganwm.

It seems to me very doubtful whether Laube’s, P. de Loriol’s, and
Oppenheim’s varieties can all remain in one species. They at least
require distinction as well-marked varieties, as follows :—

1. Var. typica of Laube. Form pentagonal ; apex blunt, and slopes leading
to it convex; margin thickened and undulating vertically; petals long.
(Character of outer ends of petals uncertain.)

2. Var. lorioli noy.; based on P. de Loriol’s type. Form pentagonal; apex
as a well-raised point, with slopes leading to it concave ; margin thin and fiat;
petals long and open at their outer end.

3. Var. oppenheimi nov. or sp. nov.; based on Dr. Oppenheim’s type. Test
small; form oval ; margin apparently thickened, but flat ; summit blunt; petals
short and closed. This form is probably a distinct species.

Of these three varieties, the specimens from the Operculina-
Limestone at Ain Sciahat agree best with the var..lorioli; but
they differ from it by having shorter, broad, and more distinctly
closed petals.

Cl. subplacunarius Fuchs * is a Miocene species from Siwa, which
offers some striking resemblances to Cl. biarritzensis ; but Cl. sub-
placunarius has longer petals, and they are represented on Fuchs’s
figures as quite closed; the test, moreover, is flatter in proportion

1 P. de Loriol, ‘ Eoc. Ech. Kgypt.’ Palzontographica, vol. xxx, pt. 2 (1903)
p. 12 & pl. i, figs. 18-19 a.
_ ? P. Oppenheim, ‘ Die Priabonaschichten & ihre Fauna’ Paleontographica,
vol. xlvii (1900-1901) p. 92 & pl. xv, fig. 18.

3 Jd.‘ Rev. Tert. Ech. Venet. &c.’ Zeitschr. Deutsch. Geol. Gesellsch. vol. liy
(1902) p. 190.

4 ‘Beitr. Kennt. Miocanfauna Aigyptens & der Libyschen Wiiste’ Palzonto-
graphica, vol/“xxx, pt. 1 (1883) p. 47 [29] & pl. xvi [x1] figs. 1-3.

664 PROF. J. W. GREGORY ON [Nov. 1911,

to its length, and has a more even slope from the apex to the front
edge. Cl. goirensis D. & 8.,' from the Miocene of Kach, is another
similar species, as it is very closely allied to Cl. subplacunarius ;
but it differs therefrom by its wider petals.

FiBULARIA LUcIANI (de Loriol) 1880.

Echinocyamus luciani de Loriol, 1880, ‘ Monogr. Ech. Nummul. Egypte’ Mém.
Soc. Phys. Hist. Nat. Genéve, vol. xxvii, pt. 1, p. 74 & pl. ii, figs. 8-15 a.

Echinocyamus luciani de Loriol, 1883, ‘ Eoc. Ech. Hgypt.’ Paleontographica,
vol. xxx, pt. 2 (1903) p. 11 & pl. i, figs. 13 a-13 d. 3

Thagastea luciani Fourtau, 1899, ‘ Rev. Ech. Foss. Egypte’ Mém. Inst.
Egypt. vol. i, fase. 8, p. 642.

Distribution.—Egypt: Middle Eocene, Mokattam and Wadi
el Tih, near Cairo. Cyrenaica: Middle Eocene, in white marly
limestone (at 1215 feet above sea-level), near the foot of the
escarpment north of Cyrene.

Dimensions in millimetres :—

Larger specimen. De Loriol’s type.
Wen thitee ccc nsdn 55 3 to 11,
Breadth sft oe 4:5 66-73 per cent. of length.
Hieip bie Se eetonsonsene 3°0 55-69

9 29

Affinities.—The collection includes two specimens (Cy 78) of
a Fibularia from a bed of soft marly limestone cropping out north-
east of our camp at Ain Sciahat, below the Roman road to Mersa
Susa, and beneath the soft shelly limestone (Cy 77) on the face of
the upper escarpment. As only two specimens were collected, it is
not advisable to destroy one in order to verify the absence of the
septa—the essential distinction between Fibularia and LKchano-
cyamus: for the echinoids have the height and egg-shaped form
characteristic of /ibularia. Agassiz indeed separated /ibularia
from chinocyamus by its subglobular form.

De Loriol described the species as subconical, and remarked its
affinity to fbularia. Fourtau in his ‘ Revision’ has transferred the
species to the genus Thagastea of Pomel; but, as he says that the
only difference between Uhagastea and Fibularia is that the former
is more elongated and irregular in shape, the genus appears un-
necessary. The smooth anterior peristcmal depression, which Pomel
used as the essential feature of Zhagastea, is even less adequate as
a generic character.

The nearest allied species is the Echinocyamus rotundus of Duncan
& Sladen,? from the Upper Eocene or Khirthar Series of Sind.
That species is much higher than is usual in Hchinocyamus ; its
length is 9 millimetres, its breadth 8°75 mm. and height 5 mm.;
but, if EL. rotundus be a Fibularia, it can be distinguished from the
Cyrenaican species by the upper surface rising to a sharp summit

1 P.M. Duncan & W. P. Sladen, ‘Foss. Ech. of Kachh & Kattywar’ Pal.
Ind. (Geol. Surv. India) ser. xiv, vol. i, pt. 4 (1883) p. 59 & pl. xii, figs. 14, 16.

2 Pp. M. Duncan & W. P. Sladen, ‘Foss. Ech. W. Sind’ Pal. Ind. (Geol.
Surv. India) ser. xiv, vol. i, pt. 3, fasc. 3 (1884) p.135 & pl. xxv, figs. 33-87.

Vol. 67. ] THE FOSSIL ECHINOIDEA OF CYRENAICA. 665

at the anterior end of the test. The same character occurs in the
Langhian Pibularia pseudopusilla Cott., of Sardinia.’
Among species from higher horizons, it is natural first to compare

the Cyrenaican specimens with £. studert (Sism.), as that species

was referred by Sismonda to Fibularza; but, as Agassiz & Desor
remarked, when referring it to Hchinocyamus in the ‘Catalogue
Raisonné,’* it is very elongated and ‘tres plate. The Maltese
specimens figured in 1891? as E. studeri are far more depressed
in form. They have since been separated by M. J. Lambert as
F, melitensis,* owing to their less oval shape and less marginal
periproct than the specimens figured by G. Capeder as Z. studeri’
but, according to the latter, the specimens which he refers to
E. studeri have a ratio of height to length of 1 to 1:9 mm. (op. et.
p. 508}, which does not correspond with the statement in Agassiz’s
diagnosis that the form is ‘tres plate.’ According to M. Lambert,
H. studeri is even flatter than a species in which the ratio of height
to length is as 1°5 to 4:25.° Signor Capeder has described twenty-
five species, of which nineteen are new and come from one locality
in Sardinia. On those lines the Maltese specimens should be
distributed among several species.

Gauthier" has described Echinocyamus thuilei from the Helvetian
of Gebel Geneffe near Suez; this echinoid is 12 millimetres long,
9 mm. wide, and 3-5 mm. high, so that it is much flatter than the
specimens from Cyrene.

The flat upper surface of the Cyrenaican specimens resembles
that of Fibularia calarensis Lambert (loc. cit.), from the Helvetian
of Cagliari; but that species is nearly thrice as long as high (1°5 to
4-25 mm.).

ScUTELLA TENERA Laube, 1868.

Scutella tenera Laube, 1868, ‘ Beitr. zur. oes d. Ech. Vic. ert.
Donkschr. K. Akad. Wiss. Wien, vol, xxix, cng 2, p. 18 & pl. i, fig.7-

Scutella tenera Dames, 1877, ‘Ech. Vic. & Ver. Tert.’ Paleeontographica,
vol. xxv, p. 22.

Scutella tenera Oppenheim, 1902, ‘ Revis. Tert. Ech. Venet. &c.’ Zeitschr.
Deutsch. Geol. Gesellsch. vol. liv, p. 192.

Scutella cavipetala Laube, 1868, op. cit. p. 17 & pl. ii, fig. 6.

1 See, for example, J. Lambert, ‘Ech. Foss. Terr. Mioc. Sardaigne’ Abhandl.
Schweiz. Palaont. Gesellsch. vol. xxxiv (1907) pl. iii, fig. 19.

2 L. Agassiz & E. Desor, ‘ Cat. Rais.’ Ann. Sci. Nat. [Zool.] ser. 3, vol. vii
(1847) p. 142.

3 J. W. Gregory, ‘The Maltese Fossil Echinoidea’ Trans. R. Soc. Edin.
vol. xxxvi, pt. ill, no. 22 (1891) pl. i, figs. 8-10 ¢.

4 J. Lambert, ‘Ech. Foss. Terr. Mioc. Sardaigne’ Abhandl. Schweiz. Paliont.
Gesellsch. vol. xxxv (1908) p. 127.

5 ‘ Wibularidi del Miocene medio di 8. Gavino a Mare (Portotorres) Sar-
degna’ Boll. Soc. Geol. Ital. vol. xxv (1906) pl. x, figs. 5 a-5 d.

° J. Lambert, ‘Ech. Foss. Terr. Mioc. Sardaigne’ Abhandl. Schweiz. Palaont.
Gesellsch. vol. xxxiv (1907) p. 40 & pl. ii, figs. 27-31 (Fibularia calarensis).

7 In Fourtau, ‘Rev. Ech. Foss. Egypte’ Mém. Inst. Egypt. vol. iii, fasc. 8

(1899) p. 696 & pl. ii, figs. 11-13.

666 PROF. J. W. GREGORY ON [ Nov.ngame

Dimensions in | Cy 60 S. striatula SS. tenera S. cavipetala
millimetres. y Cotteau’s fig. Laube. Laube. |
(Aen SED occ. a cece emma OO 50 | 56 67
MBréadth v0 ee 57 52 | 58 68
_ Antero-lateral Peay — |
| Length . ae iu 13 iit 16
| Breadth .. ae 6 5 5'5 8
| Distance from ciel
| end of that petal to '|
| margin of test ......... iy 22 23°5 25 32

Distribution.—Lower Oligocene: Tongrian of Northern Italy ;
in the tuffs at Laverda, Gnata di Salcedo, and Sangonini di Lugo,
In Cyrenaica, in the Slonta Limestones at Labruk (Cy 60); Bir Hu,
5 miles south of Cyrene (Cy 297); and ?north of Ain Sciahat
Cy 73).

Affinities.—Dames has pointed out bey the depression of the
petals in S. cavipetala was due to pressure, and that the species
must be merged in SN. tenera.

This species is represented by three specimens; but the third,
found at Ain Sciahat, is poorly preserved, and its identification is
somewhat doubtful.

The species resembles in outline Scutella ammonis Fuchs, from
the Miocene of Siwa, which has, however, longer petals. In
S. tenera the ratio between the length of the anterior petal and
the distance from its inner end to the edge of the test is as 11 : 27,
whereas in S. ammonis the ratio is as 16:29. The petals of
S. tenera are also broader and more ovate than in S. ammonis.

Scutella tenera is unquestionably closely allied to S. striatula
Mare. de Serr., the well known Lower Oligocene species, the range
of which has been extended down to the Middle Eocene by Cotteau !
in the Gironde, and to the Priabonian by Commander Flick in
Tunisia.” Laube’s figure of S. tenera has a less sinuous outline,
but that of his S. cavipetala agrees with that of S. striatula; and
S. cavipetala having been merged in S, tenera, the regular outline
is not available as a distinction. Laube remarked, as a character
separating S. tenera from S. striatula, that in the former the petals
are wider in proportion to the length; and according to that feature,
as shown by the above table of dimensions, the specimens from
Cyrenaica agree with S. tenera.

SCUTELLA sp.

A large Scutella with long petals occurs in the limestone on
the plains east of Benghazi; but the fragments collected are
undeterminable, and I was unable to return to the locality to get

1 «Beh. Koe., Pal. Frang.: Terr. Tert.’ vol. ii (1891) p. 242.
2 ‘Priabonien en Tunisie’ C. R. Acad. Sci. Paris, vol. cxxx, p. 149.

Wel, 67.) THE FOSSIL ECHINOIDEA OF CYRENAICA. 667

complete specimens. From sketches made in the field, the species
resembles S. lusitanica de Lor.’ from the Middle Miocene (beds
III-V a, of Cotter’s stratigraphical table) of Portugal.’

Scutella hunteri* Fourtau, from the Helvetian of Marmarica, is
smaller, and has shorter petals. M. Lambert has described several
new species of the Mediterranean Miocene Scutelle (S. almerat,
S. sardica, and S. tarraconensis), but they do not correspond with
my measurements of the Cyrenaican species.

The Seutella occurred with fragments of a large Clypeaster,
which supports the probable Miocene age of this limestone.

AMPHIOPE DUFFI, sp. nov. (Pl. XLVII, figs. 2 & 3.)

Test thin, breadth approximately equal to the length. The
greatest breadth is behind the apical disc. The test contracts
slightly towards the anterior end. Margin slightly sinuous. The
front half of the test is thicker than the posterior half. The petals
are oval; the length is about equal to half the distance from the
centre of the test to the margin. Apical disc central. Lunules
wide and suboval, but bluntly pointed at the ends: the lunules
occur near the edge of the test.

Dimensions in millimetres :—
Cy 264. Cy 66. A. arcuata.

Wren ise... ce. ack: Be Beam eee Ae 4] 80
Breadth 2-2 e.sece ce Be aan ouatacits 35 4] 80
Ee rein ine soe se vosict tee oness cat. cence 2 2°5 8
Antero-lateral petal: length...... 8 9

Do. do. breadth... 4 4°5

Distribution.—In a nummulitic limestone: Sidi Rof Diasi-
asia, south-east of Cyrene (Cy 66). Near the camp at Ain Sciahat,
Cyrene (Cy 264). Both specimens occur in nummulitic limestone,
and Mr. R. B. Newton remarks that the specimen from Ain
Sciahat inciudes foraminifera resembling Nummulites complanata.

Affinities.—This species is interesting, owing to the early
occurrence of the genus. Both specimens are poorly preserved, as
well as some fragments which appear to belong to this species;
but the lunules are shown so distinctly that there can be no doubt
of the generic determination ; and the genus is most abundantly
represented in the Miocene.

The nearest ally of this species is A. arcuata (Fuchs) from the
Miocene of Siwa. The two species, however, differ, as in A. duffi
the test tapers less anteriorly, the petals are oval rather than clavate,
the lunules are rather more pointed, and the size is much smaller.

1 ‘Ech. Tert. Portugal’ Dir. Trav. Géol. Portugal, 1896, p. 12 & pl. ui,
figs. 1-3.

2 Ibid. pl. v, p. 50. :

> D. H. Pachundaki, ‘ Contrib. Etude Géol. de Marsa Matrouh (Marmarique)’
Rev. Internat. Egypte, vol. iv (1907) p. 24 & pl. ii, fig. 3.

4 Named after my colleague in the expedition, Mr. M. B. Duff, to whom is
due the topographical map.

Qn J. G. Ss Nox2es: 22

668 PROF. J. W. GREGORY ON [Nov. 1911,

I originally regarded these specimens as young forms of A. arcuata.
Dr. Pervinquiere’ has reported an Amphiope with ineompletely
closed lunules, from the Priabonian of Tunis.

AMPHIOPE Sp.

The collection also includes a fragment (Cy 82) of an Amphiope
with long lunules, from the Aquitanian Pecten Bed at Ain Sciahat.

EcHINOLAMPAS.

The collection includes a series of specimens of Kchinolampus of
which the specific determination is difficult, as most of them have
been damaged by sand erosion.

The genus Hehinolampas includes a large number of species
distinguished mainly by the shape of the test, a character of
uncertain value; and, although the approximate stratigraphical
horizon may be safely inferred from a number of specimens, the
specific identification of single specimens is usually difficult in this
genus. |

The specimens of Hcehinolampas were mostly found in Central
Cyrenaica, and the chief Kchinolampas Bed is a well defined horizon.
The matrix of most of the specimens contains foraminifera, which
Mr. Newton has determined as nummulites; and Mr. Chapman
has identified specimens from this bed as Nwmmulites gizehensis,
var. lyelli. The Hchinolampas was uever found associated with
the Middle Eocene form of WV. gizehensis, buf with the later smaller
varieties.

It is natural at first to compare the Hchinolampas with those
from the Egyptian Hocene, which contains many easily recognizable
species such as LH. osiris, H. africanus, EH. crameri, E. globulus, but
none of them were found in Cyrenaica. Nine species of Hchino-
lampas are described by Dr. Oppenheim from the Priabonian beds
of Northern Italy ; but the most easily determined of those species,
such as the massive H. montevialensis Schaur., or EL. beaumonti Ag.,
are not represented. The most abundant of the Cyrenaican Echino-
lampads is a species with a subpentagonal outline, a concave base,
and having the summit of the test behind the apical disc. Different
varieties are more rounded and oval in plan, or are higher, or have
the posterior half of the test more expanded.

The general practice in regard to this genus is to treat these
variations as specific; but M. Lambert, who has had especial ex-
perience of the genus, has kindly examined six of the specimens
representing the different forms. He regards them all as individual
variations of a single species, which includes also the Upper Eocene
Tunisian echinoids originally referred to H. perriert. He says in a
letter :—

‘En résumé, sans trancher la question de l’identité de lH. perriert de la

1 «Etude Géologique de la Tunisie Centrale’ Carte Géol. Tunisie, 1903,
p- 200.

Vol. 67. | THE FOSSIL ECHINOIDBA OF CYRENAICA. 669

Tunisie avec l’E. perrieri de | Egypte, je crois qu'il existe dans l’Afrique du
Nord, dans la Cyrénaique et la Tunisie, un Hcehinolampas de forme assez
variable, a pétales plus ou moins développés, qui eonstitue une espéce
actuellement réunie par les auteurs a l’H. perriert de Loriol des environs de
Thébes.

‘Je n’hésite done pas a déterminer ces Echinolampas Nos. 229, 279, etc.,
comme Lchinolampas perriert Cotteau, mais je n’ai pas de matériaux suflisants
pour affirmer lidentité de cette forme avec l’E. perrieri de Loriol.’

M. Gauthier has established the name Z. chericherensis for these
Tunisian echinoids, and that name may be provisionally accepted.
The inclusion of such wide variations in one species will render
necessary the abandonment of several accepted species, and the
name chericherensis will doubtless have to be abandoned in favour
of some earlier name; but it may be conveniently used until this
group of species has been revised.

EcHINOLAMPAS CHERICHERENSIS Gauthier, 1899. (Pl. XLVIII,
meses lig. Lbs 2; Pl XL IX figs. iL —3.)

Echinolampas chericherensis Gauthier in Fourtau, 1899, ‘Rev. Ech. Foss.
Egypte’ Mém. Inst. Egypt. vol. iii, fase. 8, p. 732.

Echinolampas chericherensis Pervinquiére, 1903, ‘ Géol. Tunisie Centrale ’
Carte Géol. Tunisie, pp. 198, 200, 201, 202, 204.

Echinolampas perriert Cotteau, 1890, ‘ich. Koc., Pal. Frang.: Terr. Tert.’
vol. ii, p. 126 & pls. cexli, cexlii, figs. 1-2.

Echinolampas perriert Gauthier in Fourtau, 1899, op. cit. p. 659.

Echinolampas perrieri Flick, 1900, ‘ Priabonien en Tunisie’ C. R. Acad. Sci.

Paris, vol. cxxx, p. 149.
Non Echinolampas perrieri de Loriol, 1880, ‘Monogr. Ech. Nummul. Egypt.’

Mém. Soc. Phys. Hist. Nat. Genéve, vol. xxvii, pt. i, p. 95 & pl. v, figs. 2-2 b.

Non EKchinolampas perrieri de Loriol, 1883, “Boe. men Haat Paleonto-
graphica, vol. xxx, pt. 2, p. 25 & pl. vil, figs. 2-3 a.

Echinolampas zignoi Oppenheim, 1900,‘ Priabonaschichten’ Palzeontographica,
vol. xlvii, p. 103 & pl. ix, figs. 3-3 6.

Echinolampas hydrocephalus Oppenheim, 1900, ibid. p. 103 & pl. xvu,
figs. 5-5 6b.

Echinolampas blainvillei Oppenheim, 1900, ibid. p. 102 & pl. ix, figs. 1-1 6.

Non Echinolampas blainvillei Agassiz, 1847, ‘Cat. Rais.’ Ann. Sci. Nat.

[Zool.] ser. 3, vol. vii, p. 164.
Non Echinolampas blainvillei Tournouer, 1869, ‘ Rec. Ech. de l’Etage du Cal-

caire A Astéries du S.O. de la France’ Loies Soe, Linn. Bordeaux, Folk XXVIi,
pp. 286-90 & pl. xvi, figs. 1-3.

The echinoids referred, in deference to M. Lambert’s opinion, to
one species include five main variations.

The commonest form (var. @) most resembles Dr. Oppenheim’s
blainvillei, with a pentagonal form and a well-rounded upper
surface.

Var. 6 is a more flattened variety, which is also subpentagonal ;
it has affinities with #. falloti Cott.,’ but is more depressed.

Var. ¢ approaches most nearly to the Tunisian forms figured by
Cotteau, which may be regarded as the type of LE. chericherensis.

Var. d is the same as Dr. Oppenheim’s £. hydrocephalus.

Var. ¢ is unusually wide behind, and approximates to the
Tongrian H. posterolatus Greg.

1 @. Cotteau, ‘Ech. Eoc., Pal. Frang.: Terr. Tert.’ vol. ii (1894) p. 737 &

pl. ecelxxix, figs. 1-3.
222

670 PROF. J. W GREGORY ON [Nov. 1911,

Dimensions in millimetres.—The following list shows the
range of variation in shape and size :—

Var. a.
Length. Breadth. Height.
Oy GOs dhabrulk seeeeete ean 56 52 25
sd (ih pleaeee acters a 58 54 24
131. East of Wadi Gharib 49 45 23
229a. East of Slonta ...... 51°5 50°5 22°5
229. + Do. cola ly pee ? 50? 22
284. South of Wadi Firyah 53 50°5 23
DOD. SS lOnta eee eee eco ae 60 05 25
267. Wadi Firyah ......... 51 45 ? 24
Qi ae Ore MAO ha. sates ato 56 25
291. North of Roman Camp,
north-westof Slonta ? 54 27
Var. 0:
(a AN ec epheee Saaeen eae aes 59 57 21°5
LSS canes A oan ame Ame oe 56 51 ? 23
GO reertecy ete uc caiansiimnise 57 52 22
Bile Mawes venient scepter 55 51 21
; 55 47 27
E. falloti Cotteau { 5] 45 on
Waretc.
2 Peet eat neat er ial 50 28
TS, Soe CE 60 250 25
DOE» alias tee es Moments ae 55 51 28:5
E. perriert de Loriol . 52/56 82°/, 42/45 °/,
Do. Cotteau... 62 DD=COe/G 28 —s01e
E. zignot Opp. vcs. 49 84°/, 43/6
Var. d
LoL ety pes tee Eee eRe Ra 59 57 30°5
7 CARE ee an cas AT. 46 23.
cS eer ee Lees te ee ee 56 Silsg 29
VAS | OER Ane. ts oe NET A 55? 52 26°5
DODGE Ee. cece ee ee Ses 55? 49 28
Dr. Oppenheim’s { 53 45 27 Li:h as 2:1
hydrocephalus ...... ida 64 34 L:has 7:3

Distribution.— Upper Eocene: characteristically Priabonian in
Tunisia, in the Wadi Cherichera, G. Gebil (Djebil), Gebel Nasser,
Allah, Gebel Baténe and Wadi Bogal, etc.; in Northern Italy at
Lonigo, Possagno, etc.

? Bartonian : beds with Nummulites fichteli, east of Siwa.

Cyrenaica: in the Slonta Limestone.

Var. a at Labruk, east of Wadi Gharib (the westernmost locality
at which Echinolampas was found); Messa; Wadi Firyah; and
between Wadi Firyah and the shrine of Sidi Mahomet Mahridi,
east of Slonta; north of the Roman Camp, north-west of Slonta.

Var. 6 at Wadi Jeraib, east of Gasr el Migdum (Cy 144);
Labruk (Cy 60); Wadi Firyah (Cy 279); Bir Hu, 5 miles south of
Cyrene; 2 miles south-east of Messa (Cy 217).

Var. c: Ain Sciahat.

Vol. 67. ] THE FOSSIL ECHINOIDEA OF CYRENAICA, 671

Var. d: Slonta (Cy 295a and 151); east of Slonta (229); with
Fimbria lamellosa and Scutella sp., at some old cisterns, east of
Slonta (294 a).

Var. ¢: plateau near Messa; and south of Wadi Firyah, north-
east of Slonta.

Ecuinotampas piscus Desor, 1858.

Echinolampas discus Desor, 1858, ‘Syn. Ech. Foss.’ p. 307.

Echinolampas discus Dames, 1877, ‘ Ech. Vic. & Ver. Tert.’ Paleontographica,
vol. xxv, p. 43 & pl. iii, figs. la-le.

Echinolampas discus Oppenheim, 1902, ‘ Rev. Tert. Ech. Venet. &c.’ Zeitschr.
Deutsch. Geol. Gesellsch. vol. liv, p. 216.

Distribution.—Italy: Schioschichten, Aquitanian. Castello
di Schio, Rocca di Garda, ete. Cyrenaica: in grey Operculina-
Limestone, 150 feet above the Fountain of Apollo, Ain Sciahat,
Cyrene.

Dimensions in millimetres :—

Cyrene Daimes’s EL. amplus
No. 9. figured specimen. Fuchs.
engi Beh ieyn or ee about 90 73 120
TSTHEP OU Nich aes aan 86 68 110
PIBICUG foo oceumete ce. -oac 26 30 oT
(a little flattened
by crushing).

Affinities.—This species has been recorded by Cotteau from
the Hocene of Alicante in Spain; but Dr. Oppenheim throws doubt
on the identification, and it requires confirmation. Dames regards
Lanbe’s Echinolampas conicus'! as a synonym, although Laube’s
figure represents the apical disc as behind the centre, instead of
well to the front; the antero-lateral ambulacra of HE. conicus are
also represented as straighter.

The species is closely allied to H. amplus, Fuchs* from the
Miocene of Siwa; but H. amplus is flatter, and has a more central
apex and broader poriferous zones in the ambulacra.

HyYpsocLyPEUS HEMISPHERICUS (Gregory), 1891.

Heteroclypeus hemisphericus Gregory, 1891, ‘Maltese Foss. Ech.’ Trans. Roy.
Soc. Edin. vol. xxxvi, pt. iii, No. 22, p. 598 & pl. i, figs. 11 alle.

An echinoid (Cy 48) from Birlibah raises the question of
the relations of the genera Heteroclypeus and Conoclypeus to the
Echinolampads. This specimen has most of the base broken away ;
but the upper surface is well-preserved, and the chief characters of
the peristome can be recognized. It belongs to the Maltese species
founded in 1891, under the name of Heteroclypeus hemisphericus,

1 G. C. Laube, ‘ Beitr. Kennt. Ech. Vic. Tert.’ Denkschr. K. Akad. Wissensch.
Wien, vol. xxix, pt. ii (1868) p. 25 & pl. v, figs. 2@-20.

2 T. Fuchs, ‘ Beitr. Kennt. Mioc, Mzypt.’ Paleontographica, vol. xxx, pt. 1
(1883) pp. 45, 63 & pl. xiv (ix), figs. 5-8.

672 PROF. J. W. GREGORY ON [Nov. rort,

of which specimens had been previously identified by Wright’ as
Conoclypeus plagiosomus Ag. That species was founded by Agassiz”
in the ‘Catalogue Raisonné’ on specimens from the Molasse of
Southern France, and he then described it as

‘renflée, 4 bords tranchants, remarquable par ses zones poriféres trés étroites.’

Figures showing these characters have been given, as, for example,
by Laube*; and they also show that the peristome has very pro-
jecting bourrelets. In the Maltese species the peristome is very
different from that of C. plagiosomus, as may be seen by comparison
of Laube’s figure with that of H. hemisphericus.* The resem-
blances, however, between the two species and the inversion of
the peristome led me to assume that the Maltese echinoid had small
jaws, though no fragments of them had been found. I accordingly
referred the species to Cotteau’s genus Heteroclypeus. Dr. Stefanini’
has called attention to the probably complete absence of jaws, and has
removed the species from the Conoclypeide to the Cassidulide, a
conclusion which seems to me correct; but Stefanini has gone further
than I can follow him in placing the species in Hchinolampas.
The genus Hchinolampas includes a large number of species, and it
seems to me undesirable to include this very distinct type in it.
Echinolampas was founded by J. E. Gray* in 1825, but he did
not then distinctly select any one species as a type. Of the species
that he mentioned, EL. oviformis was the best known and has been
practically adopted as the type. The Hchinolampas from Malta
and Birlibah does not agree with this form of Echinolampad. It
is much nearer to the genus Palwolampas of Bell, with which it
agrees in its large size, its circular or subeircular shape, the
extension of the petals to the margin of the test, and the subequal
length of the poriferous areas in each ambulacrum. The Echinoid
also agrees with Hypsoclypeus of Dr. A. Pomel," in which Agassiz’s
species plagiosomus was expressly included. The difference between
Paleolampas and Hypsoclypeus is perhaps not very important, but
it is accepted and perhaps overrated by M. Lambert: it depends
mainly on the structure of the peristome. Palwolampas, according
to Prof. J. F. Bell’s diagnosis, has the bourrelets feebly developed,®

1 T. Wright, ‘Foss. Echinidea of Malta’ Q.J.G.S. vol. xx (1864) p. 483.

2 L. Agassiz & Desor, ‘Cat. Rais.’ Ann. Sci. Nat. | Zool.] ser, 3, vol. vii (1847)
p- 168.

3 ‘Heh. Csterr.-Ungar. Ob. Tert.’ Abhandl. K.-K. Geol. Reichsanst. vol. v,
pt. 3 (1871) p. 67 & pl. xix, fig. 3.

4 J. W. Gregory, ‘ Maltese Fossil Ech.’ Trans. Roy. Soc. Edin. vol. xxxvi,
pt. iti, No. 22 (1891) pl. i, fig. 11 6.

5 *Conoclipeidi & Cassidulidi Conoclipeiformi’ Boll. Soc. Geol. Ital.
vol. xxvi (1907) p. 8366; and ‘Ech. Mioc. Malta nel Museo di Firenze’ zbid.
vol. xxvii (1908) p. 456.

® «An Attempt to Divide the Echinida, or Sea-Eggs, into Natural Families,’
Ann. Phil. vol. xxvi (1825) p. 429.

7 «Classification Méthodique & Genera des Echinides Vivants & Fossiles’
Algiers, 1883, p. 63.

8 *On Paleolampas’ Proc. Zool. Soc. 1880, p. 48.

Wal: 67.) THE FOSSIL ECHINOIDEA OF CYRENAICA. 673

whereas in Hypsoclypeus the bourrelets are much more prominent.’
In this respect, the species founded as Heteroclypeus hemisphericus
agrees with Hypsoclypeus. The inclusion of this species in
Echinolampas seems impossible, without merging in that genus
several genera that are now accepted.?. The excellent figures
published by Dr. Stefanini of Airaghi’s species, Echinolampas pigna-
tarvz, show its identity, as Stefanini has pointed out, with the
HI. hemisphericus from Malta; and as there is an old-established
species of Echinolampas named hemisphericus, he merged the
Maltese species in Z. pignatarii Air. The exclusion of H. hemi-
sphericus from Echinolampas, however, allows it to retain its older
specific name, which dates from 1891.

M. Lambert? has suggested that Hypsoclypeus hemisphericus is
the young of Pomel’s H. doma.* That view seems to me improbable,
as the type of the Maltese species is both longer and wider than
any of the four specimens of H. domu of which the dimensions are
stated by Pomel. WH. hemisphericus has the height less than half
the length (64 mm. to 155 mm.); whereas, of the specimens of
Hl. doma of which Pomel gave dimensions, the height is half the
length in the figured type, more than half the length in another,
and slightly less in a third; and yet the flattest specimen is still
higher proportionately than H. hemisphericus. In H.doma the
apex is before the centre, and in H. hemisphericus behind the
centre. Moreover, H. doma is of Cartennian (that is, of Burdigalian
or Langhian) age, and H. hemisphericus is from the higher series,
the Helvetian.

HeEmiasTer scitta Wright, 1855.

J.W. Gregory, ‘ Maltese Foss. Ech.’ Trans. Roy. Soc. Edin. vol. xxxvi (1891) p. 611.
Opissaster scille Stefanini, ‘Ech. Mioc. di Malta nel Museo di;Firenze’ Boll.
Soc. Geol. Ital. vol. xxvii (1908) p. 470 & pl. xvii, fig. 7.

Distribution.—Malta: Seam No. 4 of the Globigerina Lime-
stone (Aquitanian) at Fommer Reh. In Cyrenaica: 100 feet above
the camp at Ain Sciahat.

The upper surface of the one specimen found is so damaged that
the fasciole is not visible, but the echinoid has the distinctive form
of this species. Its length is 45 millimetres, width 43 mm., and
height 35°5 mm.

* M. Lambert, however, instead of taking Bell’s one species as the type of
the genus, accepts E. hoffmanni Desor as the type, and accordingly describes
Paléolampas as having the floscelle much better developed than in Echino-
lampas, Hypsoclypeus, etc.: * Etude sur les Echinides de la Molasse de Vence’
Ann. Soe. Lettres, Sci. & Arts des Alpes-Maritimes, vol. xx (1906) p. 33.

* M. Lambert (zbid. p. 33) founded a new genus Scutolampas on E. plagio-
somus, Which he has abandoned as a synonym of Hypsoelypeus.

* * Descr. Ech. foss. Terr. Mioc, Sardaigne ’ Abhand1. Schweiz. Pal. Gesellsch.
vol. xxxiv (1907) p. 54. This question is discussed by Dr. Stefanini, who
maintains the two species, in Boll. Soc. Geol. Ital. vol. xxvii (1908) pp. 459-60.

* A. Pomel, ‘Paléont. Algérie—Zooph. Fasc. 2, Echinodermes’ livr. ii (1887)
p- 168, pl. Bii, figs. 1-3. The text refers to figures of the species in pls. B ii bis
& B iii, but these plates are not present in the Natural History Museum copy,
and were apparently never published.

674 PROF. J. W. GREGORY ON [Nov. 1911,

SCHIZASTER EDFRI,' sp. nov. (Pl. XLVII, tigs. 4a—4<¢.)

Diagnosis.—Test : cordate; the breadth is equal to or slightly
greater than the length. The greatest breadth is about half-way
along the length of the test. The test is high, and raised behind to
a prominent keel. The summit is very excentric posteriorly at
only a fifth of the length from the posterior end. The apical
disc is a little behind the centre. There is a long gradual slope
forward from the summit nearly to the anterior edge, where the
ambitus is steep and well rounded.

Petals: deeply sunk.

The anterior ambulacral furrow is long, and has long steep
parallel sides, as also small numerous pores. The pores in each pair
are bigeminate, and on the apical side of the plate is a conspicuous
granule immediately above the pore-pairs (fig. 6). The plates in

The granulation of the antervor ambulacral plates in a & b.

roy
0 oo S2=)
iis 9 FD9 te}
° a Ce (oY Ye) oS es
©) 99 0 0
Seo. oe ae C)
(ey 2)
a b

a= Sch. rimosus, after Cotteau, ‘ Pal. Frang.: Ech. Eoe.’ pl. c, fig. 5.
b=Schizaster ederi, sp. nov.

the anterior ambulacral furrows have numerous crowded granules
arranged in two rows along each plate, with about four granules in
each row. ,

Antero-lateral petals long and but slightly sinuous, with thirty
pairs of pores on each side. Postero-lateral petals short and deep,
and curved backwards beside the keel: they have twenty-two pairs
of pores on each side, of which the seven pairs nearest the apical
disc are much smaller than the others; the difference in size is
abrupt.

Periproct large and oval, pointed above and below, raised high on
the posterior wall, and beneath a slightly overhanging projection
from the keel. Peristome near the anterior edge.

Dimensions :—
Sch. desori. ’
Tae
Sch. rimosus Wright’s Wright's
Sch. ederi. (Cotteau). text. fig.
mm, mm. inches. mm.

duengthi - Jt, <thamaseogudgsaencees 48 59 2°8 54
Breagbhy tes coerce! sneetes 49 55 27 50
Veg Mibiyae S WOR Stites ct deiaus eek 32% 33 | 18 (35 ?)
Length of antero-lateral petal 16 21 13 16
Length of postero-lateral petal 10 10 0-75 1]

1 Named after Dr. M. D. Eder, the doctor of the Expedition.

Vol. 67.] THE FOSSIL ECHINOIDEA OF CYRENAICA. 675

Distribution.—In a yellow-weathering, marly limestone, near
the Fountain of Apollo at Cyrene; and at Gasr el Harib, near Derna.
Age, Aquitanian.

_ Cy 100. Type-specimen. 150 feet below camp at Ain Sciahat.
Cy 264. Broken specimen. Plateau above camp at Ain Sciahat.
Cy 102. Broken and crushed specimen. Platean above camp at Ain Sciahat.
Cy 146. Young specimen, 37°5 mm. long and 38 mm. wide (slightly crushed).
Camp at Ain Sciahat.
Cy 24. Flat crushed specimen, in soft yellow limestone. Plateau at Gasr el
Harib, east of Derna.

Affinities.—In the field—trusting only to memory of the
species—I identified this echinoid as Sch. desorz, the Aquitanian-
Langhian species from Malta. On studying the collection after my
return, I at once compared it with the Priabonian Sch. rimosus Ag.
The dimensions, as shown by the table quoted above, seemed to me
to indicate that the affinities of the species are nearer to Sch. desort.
M. Lambert, however, who has kindly examined the best specimen,
regards it as nearer Sch. rimosus, though distinct from that species,
than it is to Sch. desorz, from which he says it is ‘ bien différent.’ It
certainly is nearer to 7zmosus in some features of its shape. From
both these species the Cyrenaican Schizaster differs by its greater
breadth, which is slightly more than the length.

The granulation of the plates in the anterior ambulacral furrow of
Sch. rimosus, according to Cotteau’s figure (‘ Ech. Koc., Pal. Franc. :
Terr. Tert.’ pl. c, fig. 5), consists of sparse irregularly scattered
granules, whereas in this species the granules are crowded and
arranged in irregular longitudinal rows. ‘The antero-lateral petals
appear to me shorter, straighter, and broader than in Sch. rimosus,
though the numbers of the pores in the paired petals of r7mosus (31),
desori (30), and ederi (30) are practically the same.

M. Lambert remarks about the species that

‘ S. rimosus Desor, du Tongrien de Biarritz, est voisin, maisnon identique. Le
sillon entame davantage le bord chez le Schizaster de la Cyrénaique; son
péristome est plus excentrique, son fasciole est plus coudé. Ce Schizaster
constitue probablement une espéce nouvelle. |

Schizaster ederti may be regarded as a form tending to link
Sch. desori and Sch. rimosus. |

SARSELLA LAMBERTI,’ sp. nov. (Pl. XLVIII, figs. 3a & 35.)

Diagnosis.—Test small, heart-shaped, with a broad shallow
anterior notch. The breadth of the test is equal to the length.
The greatest width is at about two-fifths of the length from the
anterior end. The posterior end is truncate, and the straight side
there helps to impart to the test a somewhat hexagonal outline.

The test appears flat when seen from the side; the sides slope
gently down from the low median ridge. The anterior margin is

1 Named after M. Jules Lambert, President of the Civil Tribunal, Troyes,
the distinguished authority on the Kainozoic Echinoids of the Mediterranean
Basin.

676 PROF. J. We GREGORY ON [Nov. 1911,

steep and the front part of the anterior sulcus is almost vertical
for nearly the full thickness of the test.

The apical disc is opposite the widest part of the test, and the
area within the internal fasciole extends forwards as a flat platform,
from which the antero-lateral petals diverge almost at right angles.
Atrophy of the inner pores of the antero-lateral petals by the
internal fasciole has reduced them to ten pairs in the anterior zone,
while the posterior zone has thirteen pairs. The posterior zone is
very sinuous, and the middle pore-pairs are very wide.

Large tubercles rising from the depressed scrobicular pits occur
in the anterior corner of the test; there are eight before and twelve
behind each antero-lateral petal.

Periproct well raised on the posterior wall, which appears to
slope shghtly downwards posteriorly, so that the periproct would
not be seen from below.

Plastron broad, slightly raised above the lateral areas, which are
covered with crowded coarse tubercles. The plastron expands in
width gradually backwards. Owing to its elevation the plastron
has been worn, and leaves only faint traces of the small tubercles
with which it was provided.

Dimensions.—Length =42 mm.; breadth=42 mm. ; height =
16 mm.; length of functional part of antero-lateral petal=12 mm. ;
length of postero-lateral petal = 16 mm.

Distribution.—In yellow argillaceous limestone with Oper-
culina libyca: Cyrene Limestones (Aquitanian). Near Ain Sciahat,
Cyrene.

Affinities.—The genera Lovenia and Sarsella are separated by
the presence of ampulle in the former. The side of this specimen
has been cut away in order to determine their presence, but they
appear to be absent. There are some reasons for doubting the value
of this character ; but, if it be accepted, this species is a Sarsella.

The species with which, however, it offers closest resemblance
is the S. suleata of Haime, which according to M. Lambert is a
Lovenia. WS. lamberti and S. suleata differ, however, in several
well-marked characters. Thus the antero-lateral ambulacra project
forward in S. suleata more than in NS. lamberti, though they agree
in the number of pores and in the proportion atrophied by the
expansion of the internal fasciolar area. The number of big
depressed tubercles behind the antero-lateral petals is larger in
S. sulcata, there being twenty-two instead of thirteen. S. sulcata,
according to Cotteau’s figure’ (pl. xxii, fig. 2), has a rounded
posterior end, but the specimen figured on his pl. xxiii, fig. 1, has
a truncate posterior end like that of S. lamberti. S. sulcata is
therefore a variable species. The excellent series of figures of
Breynia carinata Arch. & H. given by Duncan & Sladen* show
how variable are the most conspicuous specific characters in the
genera Lovenia, Sarsella, and Breynia.

1 G. Cotteau. ‘Ech. Eoc., Pal. Frang.: Terr. Tert.’ vol. i (1885-89).

2 ¢Ech. Western Sind’ Pal. Ind. (Geol. Surv. India) ser. xiv, vol. i, pt. 3
(1885) pp. 348-54, pl. liv, figs. 1-9, & pl. lv, figs. 1-8.

-_

Vol. 67.] THE FOSSIL ECHINOIDEA OF CYRENAICA. 677

M. Lambert has kindly examined this specimen, so as to compare
it with Zovenia sulcata and his own ZL, lorioli Lb., and he regards
it as distinct from them and as a new species. He says :—

‘Elle se distingue de S. swicata Haime (Breynia) par son sillon qui ne remonte
pas jusqu’a l’apex et est remplacé en dessus par le petit bouclier plat
circonscrit par le fasciole intrapétale. &S. lorioli Lb., comme S. mauritanica
Pomel plus étroit en arriére, ont leur face postérieure rentrante, tandis que
cette face est oblique chez l’espéce de la Cyrénaique. Le S. mauritanica
Gauthier parait etre toute autre chose. 8S. anteroalta Gregory, pourvu
d’ampoules internes et 4 plastron lisse, est un Lovenia. I] en serait de meme
de Sursella duncant Gregory, @aprés les figures de Wright; ce dernier est
moins large en arriére, ses pores sont moins longuement atrophiés, le méplat
entourné par le fasciole interne est chez lui moins saillant que chez l’espeéce
de la Cyrénaique, qui me parait constituer réellement une espéce nouvelle.
Hupatagus tuberculosus Fraas, plus grand, aurait, d’aprés Gauthier, deux
des branches de ses pétales pairs qui remonteraient jusqu’a l’apex sans
satrophier ; 11 manquerait donc de fascioie interne.’

EUsPATANGUS sp.

A spatangoid from the Operculona Limestone at Ain Sciahat is
too deformed and sand-worn for determination. The restricted
distribution of the large tubercles indicates a peripetalous fasciole,
and thus the genus is either Breynia or Huspatangus. M. Lambert
has kindly examined the specimen, and suggests its comparison
with Huspatangus cossoni Gauth., from the Upper Limestone with
Nummulites, in the Gebel Cherichera in Tunisia. The subanal
area 1s worn, but the echinoid probably had a subanal fasciole and
is therefore a Huspatangus ; the species, however, is smaller, the
anterior sulcus steeper, the anterior height greater, and the front
steeper than in V. Gauthier’s* type of H. cossoni.

The Affinities of the Echinoid Faunas.

The Kchinoids belong to four horizons. The uppermost fauna is
represented by some Clypeaster fragments and the Hypsoclypeus at
Birlibah, and by the Scutellas and Clypeasters seen in the lime-
stones on the coastal plain between the foot of the Tokra Scarp and
Benghazi. The age is Miocene and probably Helvetian.

The second fauna includes Echinolampas discus, Hemiaster scille,
Schizaster ederi, Sarsella lamberti, Huspatangus sp., and Clypeaster
buarritzensis var. trottert. The typical form of the last species is
Upper Hocene. According to M. Lambert the Schizaster is a closer
ally of the Tongrian Sch. rimosus than of the Aquitanian and
Langhian species Sch. desori. Nevertheless, the evidence of these
echinoids as a whole led me to regard them as Aquitanian, and
Mr. Newton’s identification of the associated mollusca agrees with
that view. These echinoids were found in the limestones above
the Fountain of Apollo at Ain Sciahat, and on the plateau east of
Derna.

The third fauna includes the common but variable species of

1 «ch. Foss. Sud des Hauts-Plat. Tunisie’ Explorat. Sci. Tunisie, Paris,
1889, p. 91 & pl. vi, figs. 1-3.

Tay
678 PROF, J. W. GREGORY ON [Nov. 1911,

Echinolampas, provisionally referred to as E. chericherensis. This
species is widely scattered over the plateau east, west, and south of
Cyrene, around Slonta and Messa, and it occurs nearly as far west
as the Wadi Gharib; and a few specimens were found on the
escarpment to the north of Cyrene. This fauna also includes
Scutella tenera and a new species of Amphiope. Despite the
presence of the last genus, the age of the fauna is probably Upper
Kocene.

The lowest Echinoidea were found in the /ibularia Bed at the
foot of the Cyrene escarpment and in a somewhat lower limestone
containing many ect 7 spines and scattered plates; both beds
are Middle Eocene. rocks, which on stratigraphical evidence,
as well as that of the mollusca and foraminifera, are the oldest in
Cyrenaica, yielded no determinable echinoids.

The geographical affinities of the fauna are with those of the
Mediterranean Basin. The Upper Eocene (Priabonian) echinoids are
found also in Tunis and Italy ; the Aquitanian in Malta and Italy ;
the Hibularia, the one determinable Middle Eocene species, occurs
in Hgypt; but the rich Echinoid faunas of the Middle.and Lower
Eocene of Egypt are otherwise not represented in the collection.
Their absence is probably due to the fact that the beds deposited
during those periods in Cyrenaica were laid down in a deeper
sea. None of the species of the corresponding beds in Western
India have been recognized, although the faunas have certain
features in common.

Depth of the Formations, as indicated by the Echinoidea.

I'he echinoid faunas show by the rarity of the massive Clypeasters,*
common in many of the Mediterranean Oligocene and Miocene
limestones, that the Cyrenaican rocks were deposited under some-
what deeper water than that in which the Clypeaster Beds of Malta
and Italy were laid down.’

The approximate ranges in depth indicated by the echinoids
for the formation of the limestones containing them would be
from 10 to 50 (or perhaps 100) fathoms for the Miocene limestones
east of Benghazi; probably not more than 150 or 200 fathoms
for the Hchinolampas Bed in the Priabonian; perhaps as much
as 200 to 500 fathoms for the Schizaster-ederi and »Sarsella-
lambert. Bed at Cyrene. The /ibularia Mar] might be deeper, as
F. australis ranges down to 950 fathoms; and the absence of
echinoids, except delicate spines, in the chalky beds of the Apollonia
Limestones might indicate for those rocks a depth of perhaps
1000 fathoms.

1 Fragments of a thick Clypeaster were found at Birlibah, Gubah, and in
several exposures on the coastal plain about 12 to 15 miles east of Benghazi.

2 The depth at which the massive Clypeaster humilis Ag. was obtained by
the ‘Challenger’ ranged from 15 to 20 fathoms; see A. Agassiz, ‘ Report
on the Hchinoidea’ Chall. Exped., Zool. vol. iii, pt. i (1881) p. 119. The
range of Clypeaster and Echinanthus (sensw A. Agassiz) is given on p. 215 of
the same Report, as down to 120 fathoms.

Dee ie 6 ed Wi ie ie!

y NaT. S. Nat. S,

j. Fingland, Phote. Bemrose Ltd., Collo., Derby.
ECHINOIDEA FROM CYRENAICA.

he | or Cee oe” 7 aa 5 ’

J. Finglamd, Phoio.

QUART.

JouRN. GEOL. Soc. Vor. LXVII, Pr. XLVIII.

(slightly reduced) 32 (Cy. 217)

(Cy. 281)

(slightly enlarged).

Bemrose Ltd., Collo., Derby.

ECHINOIDEA From CYRENAICA.

a rer al po

sy

Quart. Journ. Geor. Soc. Vor. LXVII, PL. XLIX.

(slightly reduced). (29). (Cy. 295).

(slightly enlarged). (Cy. 144).

(slightly reduced) (45) (Cy-279).
(slightly reduced). (Cy. 144).

J. Fingland, Photo. Bemrose Ltd., Collo., Derby.

ECHINOIDEA From CYRENAICA.

Vol. 67.] THE FOSSIL ECHINOIDEA OF CYRENAICA. 679

EXPLANATION OF PLATHS XLVII-XLIX.
Puate XLVII.

Fig. 1. Clypeaster biarritzensis Cott., var. trotteri, nov. Operculina Limestone:
Aquitanian. Half a mile east of Ain Sciahat. Fig. la, the test
from above; fig. 1 4, the test from below ; both 8/9 nat. size. (Cy 98.)
(See p. 662.)
2. Amphiope duffi, sp. nov. Slonta Limestone: Priabonian. Near Ain
Sciahat, Cyrene. Natural size. (See p. 667.)
3. Amphiope duffi, sp. nov. Slonta Limestones at Sidi Rof Diasasia,
south-east of Cyrene. Slightly reduced (37/40). (Cy 66.)
4. Schizaster ederi, sp. nov. Operculina Limestone: Aquitanian. Ain
Sciahat, Cyrene. Fig. 4a, specimen from above; fig. 46, from
below ; fig. 4c, from the side; natural size. (Cy 100.) (See p. 674.)

Puate XLVIII.

Fig. 1. Echinolampas chericherensis Gauth. A specimen of var. a from Messa.

Fig. 1 a, seen from above, slightly reduced (57/59); fig. 1, the same
from the side, slightly enlarged. (Cy 281.) (See p. 669.)

2. The lower surface of a specimen of var. 4. Slonta Limestone:
Priabonian. East of Messa. Slightly reduced (52/55). (Cy 217.)

3. Sarsella lamberti sp. nov. Operculina Limestone: Aquitanian. Near
Ain Sciahat, Cyrene. Fig. 3a, specimen seen from above; fig. 3 8,
from below; slightly reduced (37/42). (Cy 274.) (See p. 675.)

Puate XLIX.

Fig. 1. Hchinolampas chericherensis Gauth. A specimen of var. } from the
Wadi Jeraib, east of Gasr el Migdum. Fig. 1 a, the lower side
slightly reduced (55/57); fig. 14, the same from the side, slightly
enlarged. (Cy 144.) (See p. 670.)

2. The uppermost surface of a specimen of var. a. Slonta Limestones.
Slightly reduced (55/59). (Cy 295). (See p. 670.)

3. Specimen of a variety from the Wadi Firyah. Slightly reduced (44/47).
(Cy 279.) (See p. 670.)

Discussion.

Dr. C. W. AnpREws congratulated the Authors on this valuable
contribution to our knowledge of the geology of a little-explored
district, and remarked that the suggestion that Crete was con-
nected with the mainland in late Phocene or early Pleistocene
times was supported by the discovery by Miss Bate, on that island,
ot Elephas antiquus, a dwarf elephant (Z. creticus), and a Hippo-
potamus near to H. pentlandi.

Dr. Tract referred to the approximate horizontality of the Eocene
beds over large areas both in Cyrenaica and in Egypt, and to the
great difference of level of corresponding members of this formation
in the two regions. He asked Prof. Gregory whether he had formed
any opinion as to how this difference in level was to be accounted for,
Had the whole of the vast Egyptian area been lowered by faults of
the kind to which reference had been made? He (the speaker)
thought that the paper was of great interest in connexion with the
tectonic features of the eastern half of the Mediterranean area.

Mr. A. Wane said that he was glad that the paper furnished
another link connecting Egyptian geology with that of other

680 THE GEOLOGY OF CYRENAICA. [Nov. 1911,

Mediterranean areas. He noted with interest the close structural
and paleontological connexions. The main lines were apparently
similar to those which affected the areas bordering the Red Sea, as
well as the districts surrounding the Eastern Mediterranean. He
noted also with satisfaction the further evidence of an extension of
a North African land-area in Middle Tertiary times. The chain of
evidence had now been carried from Western Egypt, through
Cyrenaica, Crete, and Cyprus, and probably farther eastwards.

Prof. Greeory explained that he had searched for terrestrial
deposits, but the whole series was of marine origin ; and any western
continuation of the terrestrial Upper Kocene beds of Egypt must be
looked for to the south of the area that he had visited.

The Cyrenaican fractures were part of a series which had affected
a vast area south and south-east of the fold-mountains of the Atlas
and the Apennines. The Cyrenaican beds had a gentle dip to the
east, and the country might be described as part of one limb of the
geosyncline of Western Egypt; but the lowering of the Miocene
limestone from the summit of the plateau of Cyrenaica to sea-level
on the Libyan coast, and of the Derna Limestone (the representative
of the Mokattam Series) to a low level in Egypt was aided by
a succession of step-faults. In regard to the problem raised by
Dr. Teall, he agreed with Suess that the difference in level could
be better explained by the subsidence of Egypt, rather than by the
uplift of Cyrenaica.

Wolt’67. | THE GEOLOGY OF ANTIGUA. 681

19. On the Gurotocy of AntIcuA and other Wrst Inpiaw IsLanpds
with reference to the PuystcAL History of the CariBEaNn
Reeion. By R. J. Lecnmers Guppy. (Communicated by
Prof. E. J. Garwoop, M.A., Sec.G.8. Read May 24th, 1911.)

[Prats L—Map. |

ConTENTS.,
Page
He pin brodemonige::....ccs2. ee meee ae wpisieonh eas snlgdoed's sa ce'atbeauad 681
II. Considerations on the Geology of Antigua................ epee 681
III. Considerations on the Geology of Barbados .................. 692
ee ihe Paria Sub-COMmement, tote goss sae tesenles 2 -dewdelende sass vie 695
V. Considerations on the Geology of Trinidad .................. 696
VI. Note on the Origin of Manjak, Petroleum, ete, ............ 699

1. InrRopvctrion.

My paper on the ‘ Geological Connexions of the Caribean Region’ ’
dealt as a whole with the' Atlantis Problem and the changes on the
earth connected therewith. Among other matters, I indicated the
course of the dislocation (which I will call the great Antillean
Dislocation) passing along the chain of the Antilles from Trinidad
to Sombrero, and thence as I suggested through the northern
part of the Island of Haiti. To make such further observations as
were possible to me despite my physical disabilities, I undertook a
voyage to Antigua and the neighbouring islands in the early part
of 1910.

In the preparation of this paper I have consulted all the
authorities available to me, but I have made most use of the papers
by Purves and Spencer. For Dr. J. W. Spencer’s papers I am
indebted to himself, and for Purves’s I am indebted to the Natural
History Society of Belgium.

II. CoNnsIDERATIONS ON THE GEOLOGY oF ANTIGUA.

Geologists and all interested in West Indian geology owe much
to men who, like Nugent (a resident) and Purves (a visitor), under-
take to furnish a careful and conscientious account of the features of
a neglected and despised island such as Antigua, High praise is
due to them. In the time of Nugent (1819) geological science was
in a backward state, and he did not therefore enjoy the means that
his successor possessed of dealing with geological subjects. Yet
Nugent’s work is the basis of our knowledge of the geology of
Antigua. He was followed by J. C. Purves, whose memoir was
published in the Bull. Mus. Roy. Hist. Nat. Belg. vol. i11 (1884-85)
p- 273. Any one who has an idea of what it is to explore geologic-
ally a tropical island must feel grateful to Purves for his elaborate
and conscientious survey. Nevertheless, in such cases there is

1 Trans. Canad. Inst. vol. viii (1908-1909) p. 373.

a i ne =
_ a -
a

682 MR. R. J. LECHMERE GUPPY ON THE GEOLOGY | Nov. 1911,

always room for expansion and correction, and it is not possible
for any observer, however honest and painstaking, to cover without
error all the problems which present themselves, and to grasp
immediately the bearing of the features which come into view.
My short visit to Antigua revealed to me how ably the work
of Purves had been done, but my physical incapacities would
certainly have prevented me from adding anything of my own, had
it not been for the kindly aid of Mr. W. R. Forrest, a gentleman
whose amiable disposition, combined with his enthusiasm for the
study of nature, induced him to assist me. Therefore, it is to him
that I owe the possibility of presenting the following notes, which
are merely remarks on and deductions from the observations of
Purves and Spencer.

Dr. Spencer’s work is based on Purves’s; but, for convenience, I
refer here to Spencer’s. His section’ across Antigua shows the
strata in the following order (omitting minor details) :—

(1) Old igneous basement = South-Western Region.

(2) Tuff series, with layers of marine cherty limestones } = Central
and also freshwater cherty beds. jo “Bien:

(3) White Limestone Series = Antigua Formation.

An orderly and apparently conformable succession of these rocks
is here exhibited, each set underlying the next one in the order
stated, so that the White Limestone appears to overlie the Tuff
Series, which in its turn is superior to the igneous series. Purves
describes these rocks very fully, and Dr. Spencer gives a summary
of his description, remarking that there is nothing in the character
of the volcanic or igneous rock to establish its age, which must
(he says) be pre-Tertiary because it underlies Tertiary deposits.
My conclusions on this point will be gathered from what follows.

It is admitted that the surface of Antigua is divided physically
into three regions, of which the boundaries run approximately from
north-west to south-east. Of these regions the south-western one is
igneous, while the north-eastern one is calcareous and sedimentary.
The middle portion between these two regions is a depression called
the ‘Central Plain,’ out of which rise several hills. It may be
broadly stated that the first-named or igneous region is a mass of
hills formed of volcanic craters and their ejectamenta, and that
they are for the most part covered by tuffs consisting of such
ejectamenta. All these are fully described by Purves and Spencer,
and the only observation that I would add on this point is that
I believe the ejectamenta to have been mostly subaérial and to have
been thrown out of the volcanic vents, forming layers which present
a stratified appearance, just as is the case with the similar deposits
of Mont Pelé in Martinique and elsewhere. The effect of heated
gases and percolating water has been to consolidate these tufts
more or less, and in varying degrees.

1 Q. J. G. S. vol. lvii (1901) p. 492.

Vol.67.] OF ANTIGUA AND OTHER WEST INDIAN ISLANDS. 683

The north-eastern region consists mainly of a calcareous formation
called by Dr. Spencer the Antigua Formation. He identifies with it
the White Limestone of Barbuda, St. Martin, and Guadeloupe, and

calls it ‘Oligocene.’ It is generally a chalky rock, varying much in
hardness and coherence, and containing numerous casts of mollusca
and other fossils. At a marl-pit about 2 miles from St. John, to
which Mr. Forrest took me, I found this rock to contain many
fossils, one of which was a Pholadomya: there were also casts of
a Turritella, This rock was fuil of small Orbitoides. I did not
detect other foraminifera or radiolaria. Proceeding to Hodge’s Bay
on the north of the island, we found a similar rock exposed on the

Fig. 1.—Outline-map of Antigua, to show the inlets, etc.
on the scale of 6 miles to the inch.

= = 7D
Sn ee =
£25 SSS ee Fb

shore, and containing Orbitordes measuring between 2 and 3 inches
in diameter, and many Pectens; but we failed to extract entire
specimens. The large size and peculiar condition of the Orbitoides
made me somewhat doubtful about them, and my workshop and
library not being at hand I could not verify the determination ;
but afterwards Dr. Lang, of the British Museum (Natural History),
was good enough to examine them and to give me his opinion that
they were truly Orbatoides (mantellii) as previously determined by
the late Prof. T. Rupert Jones. Some portions of this rock were
almost entirely composed of the smaller Orbitoides, being in this
respect quite similar to the Orbitoides Bed of Naparima (Trinidad),
Ons. |G, S, NO; 26s. 3A

684 MR. R. J. LECHMERE GUPPY ON THE @eoLoGy [Noyvy. 1911,

though in the latter only small Orbztordes have been found.’ Owing
to this resemblance, I feel convinced that other fossils, especially
fish-remains and echinodermata, will be found in this rock.

P. Martin Duncan and T. Rupert Jones wrote in the ‘ Geological
Magazine’ for 1864 on the fossils and geology of Antigua (pp. 97,
102). Their papers were based on the information supplied by
Nugent. In my ‘Second Note on the Manjak Mine’ (Trinidad,
1909) I have quoted from Rupert Jones’s paper on the Orbitordes
of Antigua to show that they are essentially the same as those of
Trinidad. Duncan’s and Jones’s papers were written long before
the time of Purves: their principal object was the chronological
correlation of the Tertiary strata of Malta and Antigua. The
Orbitoides had a great share in this correlation. So far as the
relative age of the Antiguan and Maltese strata goes, the above-
mentioned writers may be said to have made out a case; but the
assignment of the Antigua Formation to the Miocene must, I think,
in view of our present more definite knowledge, be given up. In
the discussion which followed the reading of my paper on the
Microzoic Formations of Trinidad,” Vaughan Jennings. remarked
that the difficulty (of determining the age of West-Indian forma-
tions) was due to the want of ‘accurately-localized specimens and
stratigraphical horizon.’ Hence we find Orbitoides recorded from
the ‘ Miocene’ or ‘ Oligocene,’ although it is probable that they came
from underlying or neighbouring beds. In Dr. Spencer’s paper on
Cuba certain identifications of fossils are ascribed to me, and I
believe this is correct. But, being unacquainted with the deposits,
I fear that I followed my predecessors too blindly, and did not so
carefully discriminate between fossils from different formations as I
ought to have done. I can, however, aver that personally I have
never found Orbitoides associated with the truly characteristic
Miocene mollusca. It was the differences that I observed between
the faunas of the different beds in Trinidad that induced me
gradually and tentatively to assign a more ancient date to certain
strata. And I think that further observations are needed to clear
up the alleged occurrence of Orbitoides in Miocene strata in Haiti,
Jamaica, and other islands.

This may possibly be a suitable occasion for me to say a few more
words on the correlation of West. Indian deposits of Tertiary age.
Even so eminent a Professor as J. W. Gregory has fallen into the
common error of mixing up the Miocene with the Eocene, and
calling the result ‘Oligocene.’ In his paper of 1895° he refers
to two echinoids, sent to him from Antigua as coming from the
‘Oligocene’ of that island, Of these, Echinanthus antillarum is
stated by Cotteau to be an Eocene species from St. Barts; while

1 TI have found some ‘large thin’ Orbitoides in the Orbitoides Bed of
Trinidad, but the largest of these is only 12 millimetres in diameter, whereas
the Antiguan specimens are 60 mm. in diameter and possibly even larger
than this.

2 Q. J. G.S. vol. xlviii (1892) p. 541.

3 [bid. vol. li, p. 2985,

Vol. 67.| OF ANTIGUA AND OTHER WEST INDIAN ISLANDS, 685

the other, Clypeaster concavus Cot., is stated to be from the Miocene
of Anguilla, having been previously recorded by me from that island
under the name of Cl. ellipticus. Some mistake must have crept in
here, for at any rate the St. Barts formation is definitely assigned
to the Eocene, while that of Anguilla is considered to be Miocene.
J am the more inclined to suspect a mistake as to the distribution
of the fossils, because I find that Echinolampas semiorbis, which
I described from the Miocene of Anguilla, has been assigned by
Cotteau to the Eocene of St. Barts. ‘The error is a serious one,
because Cotteau also cites H. semiorbis from Cuba, and much
confusion has already arisen in regard to the classification and
arrangement of West-Indian strata, owing to the want of due care
in stating the exact localities of fossils. I might note here that
Brissus exiquus Cotteau, a fossil originally described from Anguilla,
has lately been ebtained from Miocene beds in Trinidad associated
with the characteristic fossils of that formation.

R. T. Hill’ discusses the question of the occurrence in the
Antilles of Eocene deposits, and remarks that

‘all geologic record of the lands whence the Antillean [Eocene] deposits came
are destroyed.’

He accepts the Hocene age of the St. Barts beds, but puts the
Anguilla beds with them. Now the latter contain characteristic
Miocene mollusca, while the echinodermatan fauna is different from
that of the Eocene. He alludes to the Orbztoides and Nummuline
of Antigua as probably Eocene, and decides that certain beds in
Haiti are also of that age; and he quotes Tippenhauer in support
of this view. He makes no doubt of the Eocene age of certain
beds in Cuba.

Although W. M. Gabb refers to the occurrence of Orbitoides?
as having helped him to discriminate between the beds which
he assigned to the Miocene and to the Pliocene respectively,
yet in the numerous cases where he names the characteristic
Miocene mollusca he does not mention Orbitoides, and where he
does mention it he refrains from asserting the coexistence of
Miocene mollusca with it. It is unfortunate in this connexion
that the mollusca of the Eocene deposits are so seldom found in a
condition admitting of specific determination or description. The
name of Natica phasianelloides is given from several localities as
that of an Eocene and Miocene fossil; but the imperfect state of
the specimens does not preclude the possibility that some may belong
to another species. A fossil apparently the same, from the Tejon
(Eocene) Beds of California, has been figured under the name of
Amauropsis alveata Conr. in U.S. Geol. Surv. Bull. 396 (1909)
pl. iv, fig. 21.

While claiming for the calcareous formation of Antigua (called

1 ‘Geology & Physical Geography of Jamaica’ Bull. Mus. Comp. Zool.
Harvard, vol. xxxiv (1899) p. 177.
2 «Geology of Santo Domingo’ Trans, Am. Phil. Soe. vol. xv (1873) pp. 96,

NG, S74.
oAZ

686 MR. R. J. LECHMERE GUPPY ON THE GEOLOGY _[{ Nov. 1911,

by Dr. Spencer the Antigua Formation) an antiquity not less than
Kocene (for it is probably of the same date as the Orbitoides Bed
of Trinidad), I do not assert that all the formations correlated with
it are as old. We have sufficient reason for assuming the strata
containing Kchinolampas ovum-serpentis and Terebratula carneoides
in St. Barts to be of that age. It is denied that any Miocene
deposits exist in St. Barts; but the strata of Anguilla containing
Kechinolampas semiorbis and £. lycopersicus are reasonably considered
to be Miocene.’ Nevertheless, it is probable that Miocene as well
as Eocene strata are developed along the course of the Antillean
dislocation, and moreover that the formations found along the
Lavega Plain in Haiti contain Hocene as well as Miocene strata.
The same has been shown by Mr. G. P. Wall to be the case with the
Cumana or Cariaco depression in Venezuela,” but we still require
more evidence on this point from carefully-collected fossils. Casts
of fossils are common in many of these formations, and they simulate
equally early Mesozoic and late Tertiary or even recent shells: the
inferences drawn from them are therefore misleading, as I can state
from personal experience, and as may be seen by reference to many
geological papers where Eocene and Miocene fossils in the shape of
casts are identified with living species. 7

To go into the question of the bearing of the fossil corals of
Antigua upon the age of the formations of that island would lead
me into an enquiry too complicated for the present occasion. So far
as | can make out from a perusal of P. Martin Duncan’s papers
and of Purves’s and Gregory’s observations thereon, the evidence is
uncertain; but doubtless further light will be thrown upon the
question by renewed investigation.

We must now consider the middle region of Antigua, that
designated the ‘Central Plain’; this name can hardly be said to
be appropriate, as the ‘Plain’ is not only uneven generally, but
several hills rise in a more or less interrupted and irregular range
along the middle part of it. ‘The formations of which the ‘ Central
Plain’ is composed are fully described by Purves, who represents
them as a series of beds of tuff among which are intercalated
deposits of chert and limestone containing terrestrial and fresh-
water shells and silicified wood and corals. There is a marine
chert, as well as a freshwater chert; but for details I must refer
the reader to Purves’s paper. The important conclusion arrived
at by him is contained in these words :—

‘ La région volcanique qui s’étend depuis les bords méridionaux du Lac Taupo
jusqu’au dela de la contrée lacustre autour de Tarawera...... est certainement
celle qui présente actuellement les conditions les plus analogues a celles dans
lesquelles s’est formé le chert d’Antigoa. Cette région repose sur un fond de
tuf trachytique et de congloméré, a la surface desquels sont disséminés
de nombreux lacs, marais et lagunes au milieu et sur les bords desquels
jaillissent des milliers de sources bouillantes, fortement chargées de silice

1 The Miocene age of the Anguilla formation is confirmed by the evidence
which the fossil mollusca supply. See Q. J. G. 8. vol. xxii (1866) p. 574.
2 See Trans. Canad. Inst, vol. viii (1908-1909) p. 378.

Vol. 67.| OF ANTIGUA AND OTHER WEST INDIAN ISLANDS. 687

qu’elles déposent en se refroidissant en yastes nappes de roches affectant la
texture du silex et de la calcédoine.’ (Bull. Mus. Roy. Hist. Nat. Belg.
vol. iii, 1884-85, p. 500.)

Both Purves and Spencer in the diagrams given in their papers
_ have represented the ‘stratified tufts, that is the formations of
the ‘Central Plain,’ as passing under the Calcareous or Antigua
Formation, which is thus made to overlie these tuffs. But this is
purely hypothetical, and I do not think that it is borne out by the
evidence. J doubt whether the contact between these formations
is anywhere observable. It is much more probable that the tuffs
abut against the upraised edges of the calcareous beds, but any
such junction is hidden by the tuffs and volcanic débris of the
‘Central Plain. It is likely that the volcanic formations of
the tuffs, and the marine and freshwater cherts, etc., are younger
than the calcareous beds of the Antigua Formation. The specimen
of Orbitoides said to have been found in the chert may easily have
been derived from the adjoining calcareous rocks of older date.
And, although the fossil corals of Antigua were considered by
Duncan to have generally preponderating Miocene affinities, there
is no certainty on this point. Many of them, indeed, came from
the chert, and his ideas regarding the geology of the island, based
on the information supplied by Nugent, are entirely supplanted by
Purves’s observations.’

The Antigua Formation is of a very Cretaceous aspect, containing
Orbitoides in vast numbers and of a high degree of development,
and its other organic remains are not inconsistent with the theory
of a late Cretaceous age for it. A circumstance that might induce
one to pause before regarding the formation of the ‘Central Plain’
aS more ancient than the Antigua Formation, is the extremely
modern aspect of the fauna of the freshwater chert as enumerated
by Purves. ven though some of the species are said not to be now
living in Antigua, yet it is doubtful whether they can be distin-
guished from West Indian livingforms. The lst of fossils comprises
four freshwater shells, two terrestrial shells, and two so-called
amphibious shells. The last-named, A/elampus and Truncatella, are
never found in the water, and only within reach of the salt spray and
in sheltered places. MJelampus lives in the crevices of rocks above
high-water mark ; T'runcatella lives on the ground above high-water
mark, among pebbles and weeds. ‘These molluscs cannot lve in
water, and they, as well as the other mollusca, were no doubt
drowned in the hoé siliceous waters of the Central Plain—hence the
preservation of the soft parts in the shape of silicified casts, as
described by Purves. The identification of the shell ascribed to
Pomatias is uncertain ; it is more likely a 7’udora or a Cistula, such as
now inhabit Anguilla and the neighbouring islands. As regards the
Nematura, which is another case of uncertainty, for it is admitted
that it might be an Amnzcola (a genus common in all the West-
Indian islands), it would be nothing extraordinary, even were it
rightly identified, for we have Helv labyrinthica at the same time

* P. M. Duncan, Q. J. G. S. vol. xix (1863) p. 410,

688 MR. R. J, LECHMERE GUPPY ON THE GEOLOGY [Nov. 1911,

fossil in the Eocene of Europe and living in America even as far
south as Venezuela. Again, there is Cyrena semistrrata, a fossil
of the European Eocene also found fossil in late Tertiary beds in
Trinidad, and scarcely distinguishable from the living C. solida
of Central American rivers. Still these facts, although suggestive,
cannot be regarded as conclusive, for it 1s quite conceivable that
the freshwater chert might be (as it probably is) a later formation
than the rest of the Central Plain. We must, therefore, enquire

what aid we can obtain elsewhere in determining the relative

ages of the formations of Antigua.

In order that what follows may be more easily understood, I may
state briefly the conclusion at which I have arrived in reference
to this ‘Central Plain.’ The course of the great Antillean Disloca-
tion is shown in my paper already mentioned (Trans. Canad. Inst.
vol. vill, 1908-1909) by a curve extending from the Gulf of Cariaco
in Venezuela through the Gulf of Paria, and thence along the line
of the Antilles between St. Vincent, etc. and Barbados, and thence
northwards, turning to the west near the Virgin Islands. In the
north-eastern part of its course there are two points where the
dislocation shows itself above the sea-level, the remainder of this
part of its course being under water and inaccessible to observation
except by sounding. The two points referred to are Guadeloupe
and Antigua. This great fault, fissure, or dislocation divided the
island of Guadeloupe into two portions, the division between the two
portions being marked by a narrow channel called the Salt River.
Farther north it divided the Island of Antigua also into two portions,
the ‘ Central Plain’ of Antigua being situated upon the very fissure
itself, widened by the breaking-away of its edges and filled in by
the materials derived from the fracture and degradation of the
neighbouring rocks. Jt is not accurate to say that these islands
were divided by the dislocation; they are really the product of the
dislocation : for, while on the western side of the fissure immense
volcanic activities were brought into play, producing the chain of
the Lesser Antilles, the sea-bottom on the eastern side was elevated
and even everted, bringing up above water in a few places the
Cretaceous and Tertiary deposits formed along the margin of the
Atlantis Continent, while the continent itself was sinking. In
the case of Barbados, an offshoot eastwards of the main dislocation
elevated that island, but produced no volcanic phenomena in its
neighbourhood.

In the map appended to my Canadian Institute paper the
draughtsman omitted Antigua and the small islands in its neigh-
bourhood. The sketch-plan (Pl. L) which [now present shows on
a larger scale than that map, and better than a verbal description
could show, the probable approximate line of dislocation. The
accompanying diagrams (fig. 2, p. 689), though not drawn to any
scale, give an accurate idea of the relations of the dislocation to the
surrounding formations. The first two of these diagrams (a) & (6)
are, of course, founded on actual observation ; but the third (c),

Vol. 67.] oF ANTIGUA AND OTHER WEST INDIAN ISLANDS. 689

which represents a section of the dislocation in its course between
the islands, is hypothetical, as we are unable to get to the bottom
of the sea to investigate the strata there. I have not in these
diagrams indicated the numerous volcanic openings through which
the ejectamenta composing the islands came; but I assume that it
will be understood that, speaking generally, the line of fissure which
I have marked is the eastern edge of a broken and dislocated area,
the width of which was variable and is now occupied by the
yoleanic formations.

Fig. 2.—Diagrammatic sections across the Antillean Dislocation.

(a) Above sea-level (Antigua)
W. Igneous Central Plain Calcareous E.

> >>

[wow
EN:
I NORETAN IN IN A
CONS aaa | A IS
AN A A A A A A
A A A A A A =
A, NN AN AAG AC ALLOK
A IN RUN Sool A A \

Sea-level

Purves notices the numerous inlets, bays, gulfs, and creeks that
diversify the coasts of Antigua. Dr. Spencer, in accordance with
his theories of sunken valleys and a drowned Antillean Continent,
emphasizes those features of the island and attributes them mainly
to subaérial erosion. He says* that the prolonged denudation has

1 Q. J. G. S. vol. lvii (1901) p. 493.

690 MR. R, J. LECHMERE GUPPY ON THE GEoLoGy [Nov. 191i,

largely given rise to the physical features of the island. But, in
reality, the physical features of Antigua are mainly due to the
causes which I am about to mention, and denudation has played
quite a subordinate part in shaping the features of the island.
I have seen the effects of erosion, marine and fluvial, in many parts
of the world (for example, in New Zealand, Switzerland, Italy, etc.,
not to mention the coasts of England and Wales); but I could not
assimilate the features of Antigua to any of them. The Bocas or
channels at the entrance of the Gulf of Paria are good examples
of submerged valleys, which have been immensely enlarged by
marine erosion. Near them are sunken valleys which have not
been so enlarged. But none of them in any way resemble these
inlets of Antigua. Leaving aside for a moment the question of
whether the line of the Antilles is a submerged region, there are
several considerations adverse to the conclusion that these inlets
are due to denudation. The north-eastern coast of the island is
full of inlets and creeks with numerous islets, shoals, and banks
of all sizes. But there are no rivers in this region, which is that of
the Caleareous Formation. It is probable that the numerous irre-
gularities of this coast are produced by the solution of the rocks,
the waters both meteoric and marine attacking and dissolving the
more soluble and less coherent beds, thus eating away the land
in an irregular and uneven contour. Simple marine erosion has
usually a tendency, except where the rocks are of unequal con-
sistency, to reduce the shore to a straight line. Fluvial erosion,
other than that due to solution of calcareous matter, is absent from
this region.

We now take the case of the large inlets (See fig. 1, p. 683) known
as Falmouth, English Harbour, and Five-Islands Harbour, which
are in the Igneous Formation. They are large excavations, quite
different in shape from subaérial valleys. There is absolutely no
room in Antigua, even were the rainfall increased tenfold, for the
rivers that would be required to excavate such valleys. The raising
of the land 600 feet higher, that is to the 100-fathom line, would
ereatly enlarge the island, so that it would form one with Barbuda.
But this would not affect the question: for the rivers, even if any
could exist upon such land, the greater part of which would be
porous calcareous formations, would from their position have no
effect upon the supposed sunken valleys. The conclusion is irre-
sistible: these inlets are the remnants of volcanic craters,
and the immense quantities of matter ejected from these craters can
be seen all around in layers and beds on the adjacent hills.’

The remaining large inlets, namely the Harbour of St. John and
Willoughby Bay, are situated one at each end of the Central Plain,
and here their origin is plain enough: they are simply portions of the
fissure along the line of the great Antillean Dislocation. They are

1 In papers written some years ago (1902 and previously) I mentioned that
the harbours of Kingston (St. Vincent), Castries (St. Lucia), and St. George
(Grenada) were volcanic craters.

Vol. 67.] oF ANTIGUA AND OTHER WEST INDIAN ISLANDS. 691

both situated on the same line and in the same depression, and it 1s
impossible that any rivers capable of excavating such valleys could
be developed in a small space measuring about a dozen miles in
length by 3 or 4 in width. To meet the conditions there must have
been two such rivers running in opposite directions. This depression
(the ‘Central Plain’) is hemmed in on the east by the calcareous
formations, and on the west by the hills of the Volcanic Series ;
and there is no other land which could have supplied such rivers.
What astonishes me here is that previous observers who investi-
gated the physical features of Antigua did not at once perceive the
significance of these two inlets and the depression between them,
marking plainly the division between the volcanic region on the
one hand and the sedimentary region on the other.

It is not probable that Antigua was ever 1000 feet higher than
it 1s now, even if it was ever much higher at all. The belt of the
Antilles is rather an elevated than a sunken region. It is unlikely,
therefore, that any drowned subaérial valleys should exist in this
area. The sunken region of Atlantis lay to the east of the Antilles.
The calcareous islands are not remnants of land, but remnants
of marine formations laid down off the margins of the ancient
Atlantis, and their upheaval was more or less simultaneous with
the sinking of that land.

It is possible that the Island of Antigua marks a point where
the subterranean forces assumed a maximum of intensity ; for there
the extent of the upheaval was greater than elsewhere, and resulted
in the formation of the ‘Central Plain’ above sea-level and upon
the fissure itself. This ‘Central Plain’ thus became the theatre
of an immense development of lakes and hot springs, similar to
those of the North Island of New Zealand. The volcanic vents
of Drewhill and Boon Point supply an indication of the intensity
of the eruptions, upon and even to the east of the fissure. In the
case of Guadeloupe the edges of the fissure rose above sea-level ;
but a ‘Central Plain’ with its extraordinary development of lakes,
etc., did not arise here. In other parts the fissure was entirely
under water, and is largely filled up by the sediments from the
adjoining islands. ‘The points of greatest intensity of the volcanic
disturbances are those marked by the Antillean islands, and at
intermediate points it seems unlikely that any developments of
vulcanicity took place upon the actual fissure or line of dislocation.

The phenomena which I have endeavoured to elucidate in this
paper will probably serve as a key to some of those exhibited in Haiti
and other islands of the Greater Antilles; but, as I am unable to
pursue the investigation, I must leave it to my successors to follow
it up. I think it highly probable that the Lavega depression in
the island of Haiti, among others of a like kind, will be found to
resemble in some respects the ‘ Central Plain’ of Antigua.

There are other points upon which I might dwell in favour of
the theory here propounded, but I think that what has been set

692 MR, R. J. LECHMERE GUPPY ON THE GEOLOGY [ Noy. 1911,

forth in these pages will commend itself to all who consider the
matter carefully. I will, however, offer a passing allusion to one
other point. Purves says of the Calcareous Formation :—

‘La puissance de cette vaste formation calcaire indique qu'elle s'est déposée
pendant une longue période d’affaissement du sol quia suivi Vextinction de
Pactivité voleanique.’ (Bull. Mus. Roy. Hist. Nat. Belg. vol. iu, 1884-85,
p- 307.)

For this to be true the island must have been sunk below the
sea-level for an immense period after the cessation of volcanic —
activity, so as to permit the deposition upon it of a great calcareous
formation. Unless we suppose the relative levels of the different
parts of the island to have been greatly altered, the whole of it
(including, of course, the Central Plain, with its marine and
freshwater cherts and limestones) must have been submerged and
subsequently re-elevated. And, in such a case, how is it that the
Calcareous Formation was confined to one area instead of extending
over the whole island? But there is absolutely no evidence for
any such submergence and re-elevation, which must have left
traces of some kind upon the volcanic formations; these, however,
are intact, and, allowing for denudation, in the same state now as
when the volcanic forces ceased their activity, nor do they show
any signs of ever having been submerged. But, if we suppose as
my theory requires, that the Calcareous Formation is older than,
and was upheaved at the time of, the volcanic disturbances, all
difficulty vanishes, for this explanation is in accordance with the
facts as we see them. And this leads to a further suggestion,
which is that the volcanic disturbances occurred during the
Miocene Period and after the depositidn of the Cretaceous and
HKocene strata, and probably continued during the whole of that
Period. Further, during that Period the oceanic deposits were
accumulating in the deeper parts of the West Indian area, to be
gradually upheaved in places during the progress of the volcanic
disturbances which accompanied the sinking of Atlantis.

III. ConsipERATIONS ON THE GEOLOGY oF BARBADOS.

The same physical inabilities that beset me in Antigua also
followed me to Barbados; but, here as there, I had the good-luck
to find friends to assist me. Mr. Perey Haynes took me in his
carriage from Bathsheba, where I stayed, to Bissex Hill which we
visited together. My object there was to examine the Foraminiferal
Marl; but the exposure of it was insufficient, and the material was
too weathered to be of much use for my purposes. Mr. Haynes
gave me some specimens of sharks’ teeth (Carcharodon and
Lamna), a cast of a Plewrotomaria, and a specimen of Lchinolampas
anguille Cot. (=. lycopersicus var.), now first recorded from
Barbados: these came from the marls of Bissex Hill. J examined
a sample of these marls, and found it to consist mainly of small
Globigerine with a few other foraminifera, of which the most

Vol. 67.] oF ANTIGUA AND OTHER WEST INDIAN ISLANDS. 693

conspicuous was Uvigerina (Sagrina) raphanus, common in the
Sangregrande Beds of Trinidad.

Of course, in Barbados I had no more idea of competing with
those excellent observers, Prof. J. B. Harrison and Mr. A. J.
Jukes-Browne, than I had in Antigua of rivalling Nugent and
Purves. I only made use cf their work, in so far as it helped me to
elucidate the particular points which I had under consideration ;
and my work is merely supplementary to theirs, so far as it may
be admitted to be valid.

Mr. Labastide, Manager of the railway, took me on his trolly as
far south as Bath and as far north as St. Andrew, thus enabling
me to inspect the strata of the Scotland district exposed along the
line. In Trinidad the Orbitoides Bed is found below the manjak-
deposits. And so in Barbados I procured samples of ‘ black sand’
from the manjak and petroleum-deposits. But I found no
Orbttoides, either here or elsewhere in Barbados. What I thought
was black sand turned out on examination to be radiolarian rock
containing a very high proportion of carbonaceous matter, in fact
petroleum. There were a couple of foraminifera, namely, a small
Rotaline and a Uvigerina, but the bulk of what I had taken to be
sand was a mass of radiolaria. It is not to be supposed that
petroleum originated in the deep and clear water required for
radiolaria. I presume, therefore, that the petroleum has percolated
into the radiolarian rock from other deposits.

In this part of Barbados the strata underlying the coral-rock
being, as the Oceanic Beds usually are, of yielding materials, are
readily loosened and carried off by the springs which break out
from under the coral-rock. Thus a gradual slipping-forward of
the whole region is induced, forming a kind of undereliff. Prof.
Harrison and Mr. Jukes-Browne do not seem to think that the
coral-rock, which forms an almost continuous sheet over the Island
of Barbados, ever completely covered the Scotland district. The
rocks named the Scotland Beds are chiefly exposed in this region,
and it was to these that I turned my attention. These rocks are
stated by Prof. Harrison and Mr. Jukes-Browne to consist of
thickly-bedded sandstones, coarse grits, etc. In their report on
the ‘Geology of Barbados,’! they say that the Scotland Series
is a shallow-water formation, owing its origin to the detritus
carried down by the rivers running off a land that was com-
posed of quartz-bearing rocks. At Chalky Mount I saw a coarse
conglomerate, the pebbles in which are of some size and are
derived from a schistose or clay-slate formation, such as is found
in the northern parts of Venezuela and in Trinidad. Some of the
conglomerates were of quartzose pebbles and sand, while others
contained pebbles of clay-slate; and I thought that they bore a
stronger resemblance to fluviatile than to marine deposits, although
it is possible that some beaches under or near cliffs might be
similar. But there is no rock in Barbados whence such pebbles

1 Published by authority of the Barbadian Legislature, 1890, pp. 11 & 36.

694 MR. R. J, LECHMERE GUPPY ON THE GEOLOGY [Noy. 1g11,

could have been derived. I append a diagram (fig. 3) showing my
view of the strata of the Scotland district before the removal of a
large part of them by denudation.

Dr. Spencer * takes a somewhat similar view of the age of the
Scotland Beds, but he thinks that the material was derived from
the Orinoco. That river, however, was not in existence at the
time, and we need hardly go so far, not to speak of the difficulty
of transporting quantities of large and heavy pebbles across the
intervening space. The northern portion of South America lying
between the parallels of 10° and 12° lat. N., now partly submerged,
was nearer and was then above water. But it is more probable
that it was Atlantis itself that was the source of this material.

Fig. 3.— Diagram of strata originally exposed at OChalky Mount
(Barbados ).

Sea-level

a=Coral-rock. d=Grits.
b=Oceanic Beds. e=Conglomerates.
c~>Leda and Nucula Beds.

¢

[Great part of the strata represented in this figure has been removed
by denudation. |

I think, therefore, that while in Antigua and elsewhere forma-
tions occur belonging to the sea-margins of Atlantis, we have
in Barbados an actual fragment of that continent itself. This
statement applies principally to the lower conglomerates and
coarse grits of the Scotland Series, which I should consider to be
Cretacecus. The upper part containing fossils, among others the
Leda and Nucula described by Forbes in Schomburgk’s History,
may be Kocene; though i have shown (in Proce. Sci. Assoc. Trini-
dad, 1878, p. 170) that the Nucula is nearly allied to NV. bivirgata
of the Gault.

I am somewhat puzzled by the list of fossils tabulated by
Prof. J. W. Gregory ®; and I should not like to express any opinion
thereon, unless I knew more about them and about the beds from
which they came.

1 Q. J. G.S. vol. lviii (1902) p. 357.
2 Ibid. vol. li (1895) p. 310.

Vol. 67.] OF ANTIGUA AND OTHER WEST INDIAN ISLANDS. 695

IV. Tue Partan SuBconrinent.

To the north of the South American continent lies a sea having
a depth which does not exceed 600 feet. This area, bounded
on the north by a line approximately parallel with the coast of
Venezuela, extends as far east as long. 60° W. It is a sea full
of rocks, shoals, and islands including Tobago, and is partly in-
dicated in Dr. Spencer’s map.’ It is probable that during the
Miocene Period this area was dry land, and this land now drowned,
together with the northern part of Venezuela as far south as the
Llanos of the Orinoco, I propose to call the Parian Sub-
continent. It is remarkable that, from the point where the
line of the great Antillean Dislocation enters upon this area, no
evidences of vulcanicity appear in the neighbourhood of it. The
line of dislocation itself is well shown by the soundings which are
deeper along its course than elsewhere.? Dr. Spencer has indicated
it as one of his drowned valleys, and makes it run towards the
north; but I have shown® that the valleys parallel to and in
the neighbourhood of this all run southwards. In the Gulf of
Paria the dislocation reached a maximum, for that Gulf is due to
it. Here it divided and turned westwards, passing through the
Gulf of Cariaco, which is also due to it. Is it possible that
the reason why no volcanic phenomena arose along this part of
the dislocation was because this part was land, and accordingly
sea-water was not admitted in quantity to the inner crust of the
earth? For this northern portion of Venezuela and the adjacent
sea, including Tobago and the northern part of Trinidad, was
land all through the Tertiary Era, up to the time of the develop-
ment of the great Antillean Dislocation ; while all the region south
and west was sea, as I have on several occasions shown, and
especially in my paper on the ‘Geological Connexions of the
Caribean Region.’ I am glad here to use P. Martin Duncan’s
words, to show that he too had been led to the same conclusion,
which is borne out by Karsten’s observations on the geology of
South America :—

‘Formerly, when the great plains through which the Orinoco passes were a
Miocene sea-bottom, there may have been an open sea, as large as the Caribbean,

to the west and south, and the coral-reefs would have been supported by the
outliers of the mica-slate ranges of Colombia.’ (Q.J.G.S. vol. xxiv, 1868,

p- 15.)

And, since I wrote the above-mentioned paper (Trans. Canad.
Inst. vol. viii, 1908-1909), I have found the cogency of the reason-
ing in favour of a communication by sea between the Pacific
Ocean and the Caribean region through the Orinoco and Amazon
valleys in no way diminished.

1 Q.J.G.8. vol. Iviii (1902) pl. x.

2 See Geol. Mag. dee. iv, vol. vii (1900) p. 324.

3 See ‘Growth of Trinidad,’ Trans. Canad. Inst. vol. viii (1904-1905) p. 41.
For a further proof, see Proc, Victoria Inst, Trinidad, 1903, p. 529 (p. 512 of
original paper).

696 MR. R. J. LECHMERE GUPPY ON THE GEOLOGY __[ Nov. rg11,

As additional testimony to the Pacific alliances of the West-
Indian Tertiary fauna, I may mention here the fossil surgeon-fish
from Antigua (Zebrasoma deant Hussakof) described in Bull. Am.
Mus. Nat. Hist. N.Y. vol. xxii, 1907, p.125. The living forms of
the genus are confined to the Indian and Pacific Oceans.

I am sorry that in my paper on the ‘ Geological Connexions of
the Caribean Region’ I omitted to notice the extremely pertinent
remarks made by the late Dr. W. T. Blanford in the discussion on
Dr. Spencer’s papers on the West Indies. I owe the possession of
the report of this discussion to my friend, Mr. Robert S. Reid,
of Tobago. As Dr. Blanford’s remarks bear so strongly on the
arguments for the Tertiary Atlantis, I trust that I may be allowed
to quote them here as supplementary to my above-mentioned
paper:—

‘Omitting bats, the rodents and insectivora of Cuba, Hayti, and Jamaica
have quite as strong affinities with African as with American forms.
There are no insectivora in South America, and the North American genera
are remote from the West Indian, the nearest allies of the latter being found
in Madagascar. It is possible that the West Indian mammals entered the
country when it was part of a land extending from South America to Africa,
and since the immigration of these types, which must have been in the older
Tertiary times, there is nothing to show that the West Indies as a whole
have been united to either North or South America.’ (Q.J.G.S. vol. lviii,
1902, p. 366.)

VY. ConsIDERATIONS ON THE GroLoGy oF TRINIDAD.

Dunean’s ‘Sketch of the Geology of Trinidad’' is so full of
inaccuracies that it would occupy too much time here to correct it.
I will merely pass on to his statement (on p. 12) that the
fossiliferous deposit at St. Croix is in the same series as the cliffs
at San Fernando. I cannot admit this, nor can I admit that the
alliances of the fossils from the lmestones of San Fernando are
closer with those of the Jamaican Miocene than with those of the
chert of Antigua. My acquaintance with the fossils of the chert
of Antigua is extremely limited, and I could never have instituted
such a comparison. As to the fossils of the Orbitoedes Bed, the
list given by me at p. 572 of vol. xxii (1866) of this Journal shows
only a single species common to Jamaica, namely the Orbitoides,
and that is not Miocene. I leave out the JMatica, for it was
merely a cast; and I am not at all sure about it, though I
regarded it as a Miocene species when I wrote that paper.’ It is
true that I gave certain generic names of fossils; but, as I have
never found specimens in a condition admitting of specific
identification or description, they would form an insufficient
basis for such a statement as that made by Duncan, in face of the
facts pointing the other way.

I do not feel certain of the exact place that the Manzanilla Beds
ought to occupy, as I have failed to find anywhere else a similar

1 Q.J.G.8. vol. xxiv (1868) pp. 10-11.
2 See also Q.J. GS, vol. xlviii (1892) p. 536,

Vol. 67.]

Fig, 4.—Diagram showing the position of the Orbitoides Bed beneath the Naparima Marls, Trinidad.
(See also Q. J. G. S. vol. wlviii, 1892, p. 522, fig. 1.)
Point Bontour

k Mines

Manja

OF ANTIGUA AND OTHER WEST INDIAN ISLANDS.

oe
by
3
a
S
x
Bax

Ur bitoides Be

=-
SS)
——
——

vitoides Bed _

~Orbi

697

fauna. But I have assumed them to
be older than the Tamana and St.
Croix Beds. In any case, I have
little doubt of the Miocene age of
the latter; while the lowest beds of
the Naparima Series, namely the Or-
bitoides Bed and the Leda and Nucula
Beds, are Eocene, and pass down to
the Cretaceous. However, in his paper
on the ‘ Older Tertiary Formations of
the West Indian Islands’! Duncan
admits the Eocene age of these beds.
By the kindness of the Directors of
the Marbela Manjak Mines (Mr. James
Wilson and Mr. Bernstein) and of the
Engineer of the mines (Mr. Raspass),
I have received samples of the rocks
passed through in sinking the shafts
and adits of the mines, as well as
other information. I published a first
note on this in the ‘ Geological Maga-
zine’ for 1904 (dec. v, vol. i, p. 276);
but this was extremely imperfect, and
the subsequent information which I
acquired caused me to publish a second
note: this appeared in the Bulletin of
the Agricultural Department of Trini-
dad. A wider publicity would have
been desirable, but I was not able to
secure it. I sent, however, copies to
all persons and institutions that seemed
likely to care forthem. In this second
note I announced the discovery of the
Orbitoides Bed at a depth of 200 feet,
underlying the manjak-bearing strata.
I further discussed the characters of
the Orbitoides and their distribution,
and the origin of the manjak. The
manjak mines are situated within the
area coloured as belonging to the
Nariva Series in the map attached
to the Geological Report on Trinidad
(1860). The strata passed through in
sinking the mines represent the equi-
valents in time of the whole Naparima
Series, extending downwards from the
Miocene inclusive to the Eocene and
top of the Cretaceous. The Nariva

Series is not, therefore, a separate formation, but a part of the

1Q.J.G.8, vol, xxix (1873) p. 549.

698 MR. RK, J. LECHMERE GUPPY ON THE GEoLoGy [Nov. 1911,

Naparima Series, the differences in mineralogical characters being
due to depth of water and other conditions. This has been a much-
debated question,’ and I think that it may now be regarded as
settled. The true Naparima Marls, including the foraminiferal
and radiolarian series, were deposited in deep and comparatively
clear water; while the Nariva Series was at the same time formed
on the margin of the deep-water area, and subject to invasion by
flood-water as well as tide-water. Hence the difference in mineral
constitution. The presence of the Orbetoides Bed shows that the
Kocene formation probably underlies the whole region. It is
exposed wherever brought-up by faults or folds, as at Nos. 4, 6, 7,
8, & 15 of the sketch-section from Taruba Creek to the Oropuch
Lagoon, vol. xlviii (1892) of this Journal, p. 522. I subjoin a
modified copy of that diagram (fig. 4, p.697), showing the probable
position of the Orbitordes Bed in that section.’

When writing the paper to which I have just referred, I was
still under the impression that Orbitoides and Nummulina were
found in West Indian Miocene strata, though I had not so found
them niyself. My later experience led me very strongly to doubt
this, and to regard these foraminifera as characteristic of the
Kocene and possibly of even earlier formations. I regret that so
much confusion has followed upon this mistake, which I believe
was primarily due to the correlation of certain West Indian with
Maltese rocks considered to be Miocene but now called ‘ Oligocene.’

A noticeable addition to the fauna of the Orbitoides Bed is to be
recorded here. It is Coraw pristodontus, of which I lately found a
tooth in the Orbitoides Bed. This tooth was determined for me
by Dr. A. Smith Woodward, of the British Museum (Natural
History), and it will be seen that it adds to the Cretaceous
affinities of the Orbitoidles Bed, already fairly obvious.

The conclusions here stated vary from those set forth by
Mr. Jukes-Browne & Prof. Harrison in their paper on Barbados,’
for I place the line between the Pliocene and the Miocene at the top,
and not at the bottom of the Naparima Marls (or Oceanic Series),
But, in a note on Prof. Gregory's paper,’ Mr. Jukes-Browne says :—

‘We are quite prepared to accept Dr. Gregory’s conclusion that the Oceanic
Series is of Miocene age, the more so as Dr. Spencer has come to the same
conclusion with respect to the Radiolarian Earths of Cuba.’

As this is in practical agreement with my conclusion, I think
that it may now be regarded as clear (1) that the Calcareous
Formation of Antigua, as also the Orbitovdes Bed of Trinidad and the
Scotland Beds of Barbados, 1s Kocene (or older), and that all these
formations preceded the volcanic era ; and (2) that the Oceanic
Series of both Trinidad and Barbados are Miocene, and coeval

1 See Geol. Mag. dec. iv, vol. vii (1900) p. $22.

2 See my account of the Naparima Series (op. ezt. p. 523), where I have
indicated the position of the Orbitoides Bed at several points.

3°@. J. G.S. vol. xlviii (1892) p. 218:

4 Thid. vol. li (1895) p. 311. See also G. F. Franks & J. B. Harrison,
ibid. vol. liv (1898) p. 550.

Vol. 67.] oF ANTIGUA AND OTHER WEST INDIAN ISLANDS. 699

with the volcanic era. Once these fundamental positions are
established, the other formations in the West Indies will easily
drop into line. We are assured that the St. Barts formation is
Eocene and the Anguilla formation Miocene. It might be inferred
likewise that the Oceanic rocks of Cuba, Haiti, and Jamaica are
Miocene; but I think that it will be safer to await more certain
evidence before making quite sure.

To ayoid misconception; | must point out that in using the
expression ‘ Nariva Series’ in this paper I refer only to the series
so designated north of Naparima Hill and the Naparima Anticline,
and not to the South Naparima ‘ Nariva Series,’ about which I
am not now in a position to speak so positively.t I may simply
mention that I have found Orbitoides and Nummulina near Princes-
town, and therefore presume that the Eocene beds are developed in
that neighbourhood.

Postscript.—I had finished writing this paper before I became
acquainted with that of Prof. J. B. Harrison, on ‘The Coral-Rocks
of Barbados,’ contained in vol. lxiii (1907) of this Journal. As the
conclusions at which I have arrived, so far as they extend, are in
accordance with Prof. Harrison’s, I do not think it desirable to
alter anything that I have written. I may add, however, that his
second conclusion (p. 336) shows that the word ‘ Oligocene’ as used
by writers on West Indian geology is not only unnecessary but
misleading—inasmuch as it is applied to the Eocene of Barbados,
Trinidad, and Antigua, as well as to the Bowden Beds of Jamaica,
the Caroni Series of Trinidad, and the Miocene of Haiti and
elsewhere.

VI. Nore on tae Ortern of Mansak, PETROLEUM, ETC.

The association of carbonaceous matter with Oceanic beds is not
less remarkable in Barbados than in Trinidad. In explanation of
that fact, I cannot do better than quote an extract from my second
note on the Manjak Mines, premising merely that, as in Trinidad the
vegetable materials came from the South American continent, so
in Barbados they came from the Atlantis continent; and that the
presence of this carbonaceous matter, no less than the conglomerates
of Chalky Mount, is evidence of the former existence of that
continent :—

‘The origin of the carbonaceous substances occurring in Trinidad is to be
found in the vast quantities of vegetable matter brought down by the rivers
from the continent of South America. This matter, being ofa slightly greater
specific gravity than water, is subject to the laws which govern the removal
and deposition of sediment or clastic material. Now, one of these laws is
that material of like specific gravity, and of like fineness or coarseness of grain
or dimensions of the component parts, is deposited together and apart from
dissimilar materials. Hence the vegetable matter brought down by the
rivers was deposited in layers, banks, or strata, becoming interstratified with
other sedimentary materials as the process of sedimentation and deposition

' See J. B. Harrison & A. J. Jukes-Browne, ‘The Oceanic Deposits of
Trinidad’ Q. J. G. 8. vol. ly (1899) p. 182.

Or G8. NO. coe tae

AoOy THE GEOLOGY OF ANTIGUA. [Nov. rgit,

went on. Chemical changes supervened which converted the vegetable tissues

into the forms in which we now find them—namely, lignite, asphalt, manjak,
and petroleum.’ !

EXPLANATION OF PLATE L.

Map showing the trend of the great Antillean dislocation, on the approximate
scale of 28 miles to the inch or 1 : 1,775,000.

DIscusstIon.

Mr. G. P. Wat1, after referring to his long-standing acquaintance-
ship with the Author, which extended over more than half a century,
remarked that the geological conditions in the West Indian islands
were highly complicated, and it was difficult to collate or synchronize
the formations with those of the well-known European series, or
those of other areas. Moreover, it might be that the climate and the
environment of the tropics had not varied so much during Tertiary
times, and had not, therefore, involved that change or modification
in the succession of organisms which was so marked in temperate
climes.

In Eastern Venezuela there was a great development of Lower
Cretaceous strata, comprising vast beds of indurated limestone
rising to altitudes of 7000 feet ; the same formation was found in
New Granada and the range of the Andes, a fragment being
prolonged into Trinidad. This mountainous district was known
as the Serrania, while the Llanos consisted of undulating grassy
plains dating from Tertiary time. Similar developments of Lower
Cretaceous existed in the Jura district, where lofty, highly inclined
escarpments of compact limestone rose to great: elevations, as at
Sonceboz (11 miles from Bienne) and in the Minster Valley.

In Jamaica the Cretaceous was of later age, belonging to the
Hippurite stage. The eastern portion of that island was moun-
tainous, rising to 7500 feet, and the fossils were found in a crystalline
state; but in the western districts the conditions were simpler: the
Clarendon Valley had a floor of slightly arched limestone, crowded
with Caprina and allied genera. Rising on the flanks of this
valley were marls and loose sands full of foraminifera, probably of
transition or Hocene date—succeeded by the locally termed ‘ White
Limestone ’—a dense rock of great thickness and extension (also
developed in the adjacent large island, Santo Domingo) and recog-
nized as belonging to the Miocene Period; finally came the more
recent coastal and other beds of coralline and loosely aggregated
strata. It would appear, then, that the floor of the Caribbean Sea
consisted in part of Lower, in part of Upper Cretaceous rocks,
through which igneous eruptions had burst, forming the entire
structure of several of the islands—and weil shown on the Soufriere
of St. Vincent (3000 feet), where alternations of beds of lava, ashes,
and scoriz were inclined in proportion to the elevation, just as in
other volcanic masses (as, for example, Etna) which have been built
up by eruptive outbursts.

1 See Crosby, ‘Native Bitumens & the Pitch Lake of Trinidad’ American
Naturalist, April 1879.

Quart. Journ. Geol. Soc. Vol. LXVII, Pl, L.

TE

Lrovis
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ee ;
‘Antigua
ony

fy,

oRedonda

Montserrat

16°30. N|

h roe
SKETCH-MAP Hi SO

Showing a Portion of the
GREAT ANTILLEAN DISLOCATION

EXPLANATION:—
Line of great Antillean Dislocation =e. 16-0

Volcanic. Mariegalante
Calcareous diy

Dominicag eerie!

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Vol. 67.| GEOLOGY OF VERTAIN DISTRICTS OF CAPE COLONY. 701

20. The Geotocy of the Districrs of Worcester, Ropertson, and
Asuton (Care Cotony). By R. H. Rastatt, M.A., F.G.S.,
Fellow and Lecturer of Christ’s College, Cambridge. (Read
February 22nd, 1911.)

[Prats LI—Geocoaican Map. |

ConTENTS,
Page
I. Introduction and Bibliography ................. sls duoc tiaute tes 701
De Genera! Geological Structure:...3.5 422.5 Je- ines 24 06 se atddewene sack 702
BEE ysiopraphy, of the Ares. 124.5. ..«csteveuse sd ictas. Oe douowd erabeneee 703
Verne WM OMCESter DIGONICL. <5 ...c.c2:--sonsn-nexs a0 sesweebedcensweteceye 704
VY. The Petrography of the Malmesbury Rocks of the Worcester
TO SSINTCD lan Rea eto Alea eens RR aa ee pi A ee ee UT fa 708
(1) The Sedimentary Rocks.
(2) The Granitic Intrusions.
(3) The Igneous Rocks of Brewels Kloof.
hr Ehe Ouairetiie-hocks,of Waal Kloof -.2...-.-..005..sseseeneesedace 712
pai Pipe obermOn <DIStrict) 6. .siss23 sal ba each. nos vec wedeusoacantosess 714

(1) The Malmesbury Rocks.
(2) The Granitic Intrusion of Wolve Kloof.
VIII. The Cape and Karroo Rocks of Worcester and Robertson... 718

WEE Cher mana Cone lOmera le ).0.9250.dooncces bastwad sede ovecessleaveane 719
PrN eA SHICOA DISET IG 220. c..oncek 2b. ccccs .ccneesdercerlacesee Paes 721
XI. General Conclusions ........ Ee ee ee Ot eee os aoe 725

I. Iyrropvuction AND BIBLIOGRAPHY.

Durine the Long Vacation of 1910 I was enabled to pay a visit to
South Africa, partly for the purpose of making collections for the
Sedgwick Museum at Cambridge, and partly for original research in
South African geology. Acting chiefly on the advice of Dr. A. W.
Rogers, the head of the Geological Survey of Cape Colony, I undertook
the investigation of the neighbourhood of the towns of Worcester,
Robertson, and Ashton, in the Western Province of Cape Colony.
Owing to-special conditions, the geology of this district comprises
some features of exceptional interest, and the elucidation of the
problems there presented would cast valuable light on several
obscure features of the geological history of the country as a whole.
The most important of these problems refers to the origin and age
of the Worcester-Swellendam Fault, one of the greatest dislocations
of its kind with which we are acquainted. This forms the prin-
cipal subject of the following paper; but several other questions
are dealt with in considerable detail, especially the lithological
character and structure of the Malmesbury Series, the oldest rocks
of this part of the Colony—a subject on which hitherto little work
has been done. Incidental reference is made to other points
bearing on the principal objects of the investigation.

The district is comprised in Sheets 1, 2, and 4 of the geological
map, on the scale of about 33 miles to the inch, issued by the
Geological Commission of the Cape of Good Hope, and many

3B2

702 MR. R. H. RASTALL ON THE GEOLOGY OF [Nov. rgrt,

references to the geology are scattered through the Annual Reports
of the same Commission. The most important publications on the
geology of this region are enumerated below.

Bibliography.

Bain, A.G. ‘On the Geology of Southern Africa’ Trans. Geol. Soe. ser. 2, vol. vii
(1856) pp. 175-92.

Bain, THomas. ‘ Notes on the Geology of the Western Districts’ Cape Monthly
Magazine, ser. 2, vol. xv (1877) pp. 171-78.

Duny, E. ay Geological Sketch-Map of Cape Colony. London, Stanford, 1873.

——. Geological Sketch- Map of South Africa. Melbourne, 1887.

Hatcn, F. ei & CorRsToORPHINE, G.S. ‘The Geology of South Africa’ 2nd ed.
London, 1909.

Roeers, A. W. ‘Summary of the Work done in the South-Western Districts’
Ist Ann. Rep. Geol. Comm. Cape Colony, 1896, pp. 13-14.

Rocers, A. W., & Scpwarz, E. H. L. ‘Report on Caledon, Bredasdorp, Swellendam,
& Southern Part of Worcester’ Ann. Rep. Geol. Comm. Cape Colony, 1898,
pp. 37-54.

—— ——. ‘ Notes on the Geology round Worcester supplementary to the Accounts
published in the 1st & 2nd Annual Reports’ Ibid. pp. 83-84.

Rogers, A. W., & Du Tort, A. L. ‘An Introduction to the Geology of Cape Colony’
2nd ed. London, 1909.

RusipeGk, R. N. ‘On-some Points in the Geology of South Africa’ Q. J. G.S.
vol. xv (1859) pp. 195- 98.

Scuwarz, E. H. L. ‘Summary of the Work done in the Tulbagh Area &
Worcester District’ 1st Ann. Rep. Geol. Comm. Cape Colony, 1896, pp. 27-29.

——. [Quoted in] Report of the Geologist. 2nd Ann. Rep. Geol. Comm. Cape
Colony, 1897, pp. 3-38 & pl. 11, sections 1 & 2.

——. ‘Summary of Work done during 1897 in the Robertson, Lady Grey,
Montagu, & Eastern Parts of the Swellendam District’ Ibid. App. II,
pp. 53-58.

—. ‘Geological Survey of the Divisions of Tulbagh, Ceres, & Worcester’ 10th
Ann. Rep. Geol. Comm. Cape Colony, 1905, pp. 259-90.

)

Il. Generat Grotocicat SrRuctTurRE.

Within the area here dealt with a considerable variety of
geological formations is found, ranging from the pre-Cambrian
to the Cretaceous, but with notable and important gaps in the
succession. here is, in addition, a considerable development
of gravels, loams, and alluvium of recent origin. The most
important formation, and the one which covers the greatest area
in the district, is the Cape System; while in certain parts ‘the
strata of the Karroo System also occur to a considerable extent.

The formations now actually seen in the district may conveniently
be tabulated as follows :---

Recent gravels and loams.

Enon Conglomerate, ete. Lower Cretaceous.

ceca Shale. [
P -Ca f,
Dwyka Series. ermo-Carboniferous

Witteberg Series. Devonian and Carboniferous.
Bokkeveld Series. Lower Devonian.
Table Mountain Series. Lower Devonian or Silurian.

Malmesbury Series. Pre-Cambrian.

Vol. 67,] WORCESTER, ROBERTSON, AND ASHTON (CAPE coLony). 703

In the southern part of Cape Colony, the Witteberg Series seems
to pass conformably into the Karroo System, though towards the
north a marked overlap occurs, so that the Karroo rocks rest

unconformably on all the older systems. There is thus evidence
of a differential movement, which does not seem to have noticeably
affected the rocks of the south-west.

The Dwyka and Ecea rocks of the Worcester district resemble
in all essential details those of the Karroo area in the north,
and were undoubtedly formed in direct continuity with them;
and their present isolated position is a result of post-Karroo
disturbance.

Since the composition and characters of the Enon Conglomerate
constitute one of the most important subjects treated of in the
present paper, the consideration thereof must be deferred.

All the rocks up to and including the Karroo System have
in this area undergone important disturbances and dislocations,
and even the Enon Conglomerate shows unmistakable evidence of
earth-movement of considerable intensity ; so it is evident that in
recent times the region has been subjected to great disturbance,
and the prevalence of hot springs, as at Montagu and Brand Vley,
suggests that activity is even now by no means extinct.

II]. PaystoGRAPHY oF THE ARBA.

The region under investigation is one of very varied topography,
presenting many features of interest from the standpoint of the
physical geographer, and it illustrates with especial clearness
the relation between scenery and geological structure. There is
perhaps no part of the world where the scenery is so closely
dependent upon the character and arrangement of the underlying
rocks as in the western portion of Cape Colony; and here there has
been a complete absence of complicating factors, such as glaciation
or recent submergence and re-elevation, which have played so
important a part in modifying the topography of many northern
regions. Hence the effects of a powerful and long-continued
process of denudation can be effectively studied.

The area as before defined lies wholly or almost wholly within
the drainage-basin of the Breede River, one of the largest streams
of Cape Colony. It is bounded on the north by the Hex-River
Mountains and the Langebergen, which form one continuous range
trending roughly from west-north-west to east-south-east, and only
broken through at intervals by some of the larger tributaries
of the Breede, such as the Hex River and the Kogmans River,
both of which rise to the north of the principal range. These
mountains attain an average height of some 5000 feet, the culmi-
nating peak, Matroosberg, having an altitude of about 7400 feet.
The southern slope of the range is exceedingly steep, and this has
a most important bearing on some geological features of com-
paratively recent origin. In front of this great escarpment comes
a narrow strip of foot-hills, varying in width from 1 to 5 miles

704 GEOLOGY OF CERTAIN DISTRICTS OF CAPE COLONY. [Nov. 1911.

and usually ranging from 1000 to 2000 feet in altitude, reaching
3000 feet only in the neighbourhood of Robertson, where a
large intrusion of granite forms a conspicuous peak of 3100 feet.
Below and in front of these foot-hills stretches the broad valley of
the Breede River, which is in parts diversified by hills of con-
siderable height, but sometimes forms a plain as much as 10 miles
wide: this is bounded on the south and west by the Zonder Kinde
Mountains and other ranges. In the north-western part of the
district, north of the Hex River, the trend of the principal
northern chain undergoes a change, curving round to the north
and becoming parallel to the other mountain-chains of the coastal
region of Western Cape Colony; whereas the Langebergen beyond
Swellendam assume an east-and-west trend, parallel to the other
ranges of the south coast. As will be shown later, this change of
direction is intimately connected with geological structure, and is
of the utmost importance in the study of the tectonics of the
district.

The scenery is characteristic and in parts very beautiful, especially
in the mountain-ranges, where some of the passes, such as the Hex-
River Poort and Kogmans Kloof, show scenes of great magnificence.
The contrast is very striking between the rugged and exceedingly
steep mountains of Table Mountain Sandstone and the wide alluvial
plain of the Breede River at Worcester, which has been carved out
of the softer beds of the Bokkeveld, Karroo, and Enon formations.
The scenery of the district can be well seen from the railway, since
the main line from Cape Town to Kimberley and Johannesburg
runs through the Hex-River Pass after leaving Worcester, and
the line of the New Cape Central Railway runs along the foot of
the Langebergen from Worcester through Robertson and Ashton,
towards Swellendam and the south coast. The region is, therefore,
easily accessible.

LV. Tuer Worcester District.

The town of Worcester lies on the northern edge of the great
alluvial flat of the Breede Valley, some 5 miles south-west of
the mouth of the Hex-River Pass, which is now the principal
line of railway-communication between Cape Town and the Orange
Free State and the Transvaal. It forms, therefore, a convenient
centre and starting-point for the investigation of the district. The
outcrop of the Malmesbury Series is here unusually wide, extending
over a total distance of some 6 miles; consequently this is a
specially favourable locality for studying the general character
of the Series. The Malmesbury rocks here vary considerably in
lithological character, but the general conformation of the ground is
very uniform throughout. ‘They form an expanse of comparatively
low, rounded, rolling hills, varying in height from about 1000 to
1500 feet, diversified occasionally by small crags—or kranzes, in
the local idiom. Along the river-courses there is usually a good
deal of recent alluvium, and in some parts exposures are rather
deficient. The junction between the Malmesbury Series and the

(Total length= about 7 miles.)

io the foot of the Hew-Riwer Mountains.

oe
%

section from Worcester

srammatie

«

as, 1 == Drag

Malmesbury iS aie 6) a om esi a Ty. Grits

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~—
~
8
ce
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a)
ifs)
5

y ;/ Q

fe is

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- 5

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oe is}

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7 OoePO
RRS

T.M.S. = Table Mountain Sandstone. |

I.G. = Intrusive granite.

L. = Limestone-band in the Malmesbury Slates.

Enon Conglomerate.

[E. =

overlying Table Mountain Sandstone
is well seen in the deep kloof at the
head of the Hartebeest River, some-
times called the Fairy Glen, in
which the new waterworks for the
town of Worcester are now being
constructed.

The general strike of the Malmes-
bury Series is fairly uniform, being
on the average about west 10° north
and east 10° south. In a few
localities, and especially just to the
north of Worcester, there are small
areas of local disturbance, due to
special causes, such as igneous in-
trusions and dislocations; but these
are not of much importance. Only
one extensive rock-mass, in Brewels
Kloof, appears to be of igneous
origin : this will be separately dealt
with hereafter. Immediately north
of Worcester are some small patches
which appear to be highly meta-
morphosed granitic dykes: all the
rest of the area is occupied by
rocks of undoubtedly sedimentary
origin, which have undergone a con-
siderable amount of dynamic meta-
morphism.

The field-relations and general
characters of the Malmesbury Series
can be best illustrated by a some-
what detailed account of a section
running north and south, from the
town of Worcester to the base of
the Cape System in the Fairy Glen,
a distance of about 7 miles. ‘The
relations here disclosed are illustrated
Iya

As before stated, the town itself
stands on the alluvium of the Breede
River, which here forms a flat plain
some 4 miles wide. However, im-
mediately north of the town the
ground begins to rise, and in the
goods-yard at the railway-station
there is a very fine exposure showing
Enon Conglomerate resting upon
Eeca Sandstone that yields plant-
remains, The conglomerate is again
well exposed at the dam of the small
reservoir about a mile north-west
of the church ; and, owing to recent

706 MR. R, H. RASTALL ON THE GEOLOGY OF [Nov. 1911,

excavations, very good unweathered specimens can here be obtained.
This conglomerate forms a low rounded hill, to the north of which
is a level expanse of loam and brick-earth, about half a mile wide.
In this loam are a good many gullies (sluits) formed by streams
during heavy rains, and, at the bottom of some of these, exposures
of Eeca Sandstone can be seen. At the foot of the next slope is
an outcrop of a peculiar shattered quartzose rock, which is believed
to indicate the position of the great fault.

Immediately to the north of this are several small quarries
in which a variety of rock-types are to be seen, including a band
of white crystalline marble associated with highly-crushed granitic
dykes. This marble probably represents a band of limestone,
which has been metamorphosed by the granitic intrusions, as well
as crushed by earth-movements, and it is associated with some
greasy-looking schistose rocks of remarkable character. For some
distance north of this there are numerous bands of a hard rock,
which is called by Dr. Rogers ‘ phyllite-gneiss.’ As we shall see
presently, these are undoubtedly igneous intrusions that have
undergone foliation by earth-movement.

For some 3 miles northwards the ground is occupied by a
monotonous series of silvery, greenish or grey, fine-grained, schistose
rocks, which may be called slate, phyllite, or schist; here and
there only are to be seen thin bands of grit or quartzite, which
seem to be usually quite impersistent, and of little importance. A
somewhat thicker band of grey quartzite occurs near a sheepfold,
on a kopje about 3 miles north of the railway-station. The
phyllite or slate weathers into soft, brownish-grey, sandy flags,
which cover a great stretch of country : exposures are frequent
but of little interest.

Following the cart-track from this point over the low watershed
to the first tributary of the Hartebeest River, we note that
exposures become scarce, and a great spread of gravel and sand is
encountered, which continues for some distance. The deficiencies
of this part of the section must be filled in from parallel traverses,
made both to the east and to the west of this line.

When next exposed, higher up the Hartebeest River, the
M lmesbury rocks are represented by massive green and purple
erits of a kind not before seen: the unusual colours are probably
due to the fact that the specimens here obtained are unweathered,
coming from the excavations for the pipe-line of the waterworks.
They appear to be similar in all essential characters to the grey and
brownish grits of the Hex-River Pass, on the east. These grits
can be seen to disappear under the Table Mountain Sandstone;
the latter has a fairly steep dip to the north, and here forms an
escarpment some 4000 feet high, cut up into prominent peaks and
ridges. Where last seen, the Malmesbury Grits also exhibit a
strong dip to the north, at a much steeper angle than the Table
Mountain Sandstone.

Throughout the whole of the distance from the Worcester Fault

Vol. 67.] WORCESTER, ROBERTSON, AND ASHTON (CAPE CoLoNy). 707

almost to the foot of the mountains, a distance of about 6 miles,
the dip of the Malmesbury Beds is uniformly to the south, and
nearly always at a steep angle, often exceeding 50°. It is only at
the extreme north of the exposure, as just mentioned, that the dip

is northerly. It follows that, if there be no repetition by faulting

or isoclinal folding, the total thickness must be enormous. Un-
fortunately, the data at our command are insufficient to decide
this question. It must be stated however, that, so far as my
own observations went, I could see no evidence of repetition; and
the distinct difference of lithological character at the northern
as compared with the southern extremity of the section is, on the
whole, evidence bearing against this supposition.

Another specially favourable opportunity of examining a large
part of the Malmesbury Series is afforded by the road, which passes
along the right bank of the Hex River from De Wet Station in a
northerly direction. Some 3 miles above the station the base
of the Table Mountain Sandstone is reached, and in this distance
exposures of the older rocks are frequent. The road from Worcester
winds round the southern side of a low but steep hill, known as
Meirings Berg; and the numerous cuttings here are excavated in
a soft silvery slate, with highly developed cleavage and a generally
sericitic appearance. This may perhaps be described, for con-
venience, as silvery phyllite. Passing northwards, a more gritty
facies soon sets in; and, from a point a short distance south of
De Wet Station to the base of the Table Mountain Sandstone, the
whole may be classified as grit, with occasional quartzite-bands. The
coarser types approximate very closely to the grits at the head of
the Hartebeest River; and the direction of strike is quite in
agreement with the view that these are continuous. On these
grounds I have divided the Malmesbury Beds into two series,
as shown in the accompanying map (Pl. LI)—a series mostly
composed of grits, lying to the north, and presumably the older;
and a broad belt of slates and phyllites on the south, which appear
to be newer in stratigraphical sequence, and are cut off abruptly
by the Worcester Fault, their actual thickness being hence quite
unknown. |

An interesting and important observation was made on the main
road, on the other side of the Hex River. Near to the house
marked on the Survey map as Maze Kraal. there was found a
small exposure of a highly decomposed rock, full of small crystals
of ottrelite. It seems highly probable, in fact almost certain, that
this is the westerly continuation of the narrow band of ottrelite-
schist at Waai Kloof, near Nuy, which lies some miles to the east,
but exactly in the required direction, assuming the strike to remain
uniform, as it actually appears to do. This rock was only seen at
one point in the Hex-River Pass, but its assumed position is
indicated on the map (Pl. LI).

708 MR. R. H. RASTALL ON THE GEOLOGY OF [Nov. 1911,

V. Tue PerrograPpHy oF THE Matmesspury Rocks or THE
Worcester Districr.

As we have already seen, the Malmesbury rocks of the Worcester
district can be divided on general grounds into two series, which
differ somewhat markedly in lithological character. The lower
division is best seen in the fine road-section along the right bank
of the Hex River, north of De Wet Station, while the upper series
is well displayed in the numerous kopjes which form the rolling
ground extending for some miles due north of Worcester. The
massive grits at the base of the whole are also now well exposed,
in the excavations for the new waterworks at the head of the
Hartebeest River. A short distance north of Worcester bands of
limestone and masses of intrusive igneous rock occur in the upper
series; while the igneous rocks of Brewels Kloof form an excep-
tional type, and need separate treatment.

(1) The Sedimeatary Rocks.

(a) Lower division: the gritty series.—The rocks forming
this series are ou the whole very uniform in character, the chief
variations being in the matter of colour, which is obviously of
subsidiary importance. ‘They may be collectively described as
grey, green, or purple grits, usually massive and rather fine in
texture [9463]. When weathered, they often take on a brownish
colour; and here and there comparatively thin bands of white or
very pale grey quartzite are met with, as for example near the
farmhouse Zeekoe Gat. Passing southwards, these grits and
quartzites gradually give place to a great thickness of flags and
gritty slates, usually dark grey. These are very different from
the silvery slates and phyllites of the upper division, which begin
about half a mile south of De Wet Station.

A typical specimen of one of the grits from a short distance
north of De Wet (9459), when examined microscopically, is seen to
consist for the most part of angular and subangular grains of quartz,
with abundant small flakes of a yellowish mica and occasional grains
of tourmaline, zircon, epidote, etc., which are clearly of detrital
origin. In some specimens, but not universally, grains of felspar
occur in small quantity. ‘he grains are somewhat sparsely dis-
tributed in the cementing material, which is relatively abundant.
The cement is very fine in texture, so that its constituents are
somewhat difficult todetermine. It appears to be chiefly composed
of quartz and mica in minute grains and flakes, but a good deal of
some irresolvable argillaceous material also seems to be present.

It is noticeable that all the larger quartz-grains show a certain
amount of corrosion at the edges, as if some kind of reaction nad
taken place between the quartz-graius aud the constituents of the
cement. This undoubtedly indicates incipient metamorphism, but
whether this 1s thermal or dynamic in character, it is impossible to
say with certainty.

1 The numerals in brackets refer to slides in the Sedgwick Museum col-
lection, Cambridge.

Vol. 67.] WORCESTER, ROBERTSON, AND ASHTON (CAPE conony). 709

(6) Upper division: the slaty series,—The rocks of this
series are notably finer in texture than those just described, and
appear to have been deposited in deeper water; but they are on
the whole of very similar character, and the transition from the
gritty to the shaly type is gradual. The lower part of this series
is well seen along the Hex-River road, on the farm Meirings Berg,
and also in the neighbourhood of Brewels Kloof; while the upper
part is excellently exposed on the low hills immediately north of
the town of Worcester.

In this division, the dominant lithological type is a fine-textured
silvery-grey or olive-green rock, which has been variously described
as slate, schist, and phyllite. Cleavage and schistosity are con-
spicuous, while strain-slip cleavage, both microscopic and on a large
scale,is very common. When weathered, these rocks take on a
greenish-yellow or brownish tinge, and shatter very readily under
the influence of weathering agents.

A microscopic examination of speciniens of these rocks reveals a
structure and mineralogical composition very like that previously
described in the more gritty division, but of course on a smaller
scale. In most of the specimens from this division felspar is
fairly abundant in small rounded grains, and it is sometimes dis-
cernible also in the fine cement. The principal coloured mineral
is olive-brown biotite, which is sometimes converted into chlorite.
In these specimens also the quartz-grains show incipient meta-
morphism, indicated hy reaction with the ground-mass. Certain
beds have some resemblance to volcanic ashes, owing to the
presence of broken crystals of felspar and much micaccous
material.

In a deep sluit to the west of the flag-quarry, and north-west of
the marble-quarry, there is a small exposure of conglomerate in
the Malmesbury Series. This rock is highly schistose in character,
with augen-struktur, and consists of scattered pebbles embedded
in a well-foliated silvery phyllite, which is a good deal weathered
and stained by iron-oxide. ‘lhe pebbles, which are not relatively
abundant, vary from half an inch to 5 inches in diameter, but the
larger ones are rare; they are for the most part oval in form, and
evidently waterworn. They consist of vein-quartz and quartzite,
and do not exhibit any special characteristics. They are chiefly of
interest as showing the former existence of sedimentary rocks older
than the Malmesbury Series.

(c) The calcareous rocks.—The lmestone-baids found in
the quarry north of Worcester show a great deal of variation,
apparently due to different degrees of metamorphism, depending on
their proximity or otherwise to the invading tongues of granite.
The rocks are here much disturbed, and the relations of the different
types of limestone are difficult to make out. In one part of the
quarry there is a considerable mass of white crystalline marble, and
on the other side are some remarkably contorted bands of a black
limestone which does not seem to be much altered: this is only
a few inches thick.

-
710 MR. R. H. RASTALL ON THE GEOLOGY OF Noy. nent

The marble is a white or greenish-white rock of fine texture,
and very uniform in character. In a slice [9460] it is seen to
consist entirely of carbonates, with no other recognizable minerals.
A sample was subjected to qualitative chemical tests, and showed
no trace of either magnesia or iron, and no matter insoluble in
hydrochloric acid ; it must, therefore, consist wholly of calcium
carbonate, and is consequently a rock of remarkable purity.

A specimen of the black limestone from the other side of the
quarry was also examined in the same way: it was found to be
wholly soluble in hydrochloric acid. When the solution was
neutralized with ammonia, a very small precipitate came down,
which probably contains both iron and alumina. A trace only of
magnesia was also found. The iron, alumina, and magnesia were
all too small in amount for quantitative determination, and the
rock is practically pure calcium carbonate: therefore the chemical
composition is not inconsistent with the view that this limestone-
band is the same bed as the white marble, but less metamorphosed.

(2) The Granitic Intrusions.

About a mile north of Worcester are to be seen over a con-
siderable area frequent outcrops of a rock which has been com-
monly referred to as ‘ phyllite-gneiss.’ This is a massive strongly-
foliated rock of a grey colour, nearly always distinctly lenticular,
and often showing sericitic mica on broken surfaces. It is quite
apparent, both from a petrographical examination and from field-
relations, that this ‘ phyllite-gneiss’ represents masses of granite or
granite-porphyry which have been intruded into the sediments at
some period prior to the final foliation. The intrusive character
is not easy to determine with certainty, but I was lucky enough
to find on the ground conclusive evidence on this point. Imme-
diately west of the small hill at the foot of which the marble-
quarry is situated are several deep sluits, which have removed
the sand and loam down to the surface of the solid rock. In one
of these sluits, which is about 6 feet wide and 4 feet deep, there
can be seen a contact of the phyllite-gneiss and the slate. From
this it is clear that the granite was intruded after the major
joints of the sedimentary deposit had come into existence, since
the transgression is controlled by these; but both sediment and
intrusion alike were affected by the latest and most powerful
pressure, which produced parallel foliation in both.

When examined with the microscope [9461-62], specimens of
this rock show much less alteration than might be expected from
its macroscopic appearance. It is distinctly porphyritic, with
phenocrysts of quartz, orthoclase, and oligoclase in a fairly fine-
textured ground-mass of granulitic type, consisting of quartz and
felspar. Some patches of a dark-green chloritic mineral probably
represent original biotite. This rock is a granite-porphyry or
quartz-porphyry, of fairly acid composition and alkaline affinities.

A series of specimens of this rock collected from different points

Vol. 67.| WORCESTER, ROBERTSON, AND ASHTON (CAPE CoLony). 711

shows a regular gradation of characters, from an almost uncrushed
quartz-porphyry as above described to a highly schistose rock, con-
sisting for the most part of finely granular quartz and felspar and
sericitic mica, in which the original phenocrysts are represented
by much-flattened augen of recrystallized quartz and felspar.
The sericitic mica, which is pale brown or colourless, forms very
conspicuous streaks curving round the augen.

There is hardly sufficient evidence available to decide with
certainty what the form of these intrusions may be, but it seems safe
to conclude that they are for the most part of dyke-like habit. At
the marble-quarry there is evidence of a considerable degree of
disturbance of the strata and also of strong thermal metamorphism ;
in all probability these granite dykes are offshoots of a larger and
more deep-seated mass which is not exposed at the surface: the
form of the intrusion, as indicatec in fig. 1 (p. 705), is not to be
taken too literally, as it is merely diagrammatic and to a certain
extent hypothetical.

(3) The Igneous Rocks of Brewels Kloof.

The exact size and boundaries of this mass are somewhat
difficult to determine, owing to the roughness of the ground and the
poorness of the exposures in some parts, but it appears to be some-
what elliptical in form, and about three-quarters of a mile long by
half a mile broad. Where the contact of the igneous and sedi-
mentary rocks can be seen, the former appears to be always inclined
at a high angle, sometimes nearly vertical, and the outer portions
of the mass show a good deal of shearing. For this reason, it is
difficult to determine whether there is any difference of texture
between the outer and the inner portions of the mass.

A typical specimen of this rock, when unweathered, is dark blue
or grey in colour, heavy and compact, with a spotted appearance,
which, as can be seen from microscope-sections, is partly due to
porphyritic felspars, and partly to vesicles filled with secondary
minerals. When weathered, these secondary minerals offer less
resistance than the rest, so that the exposed surfaces frequently
show a very conspicuous vesicular pitting.

Thin slices of this rock [9464-65] reveal abundant phenocrysts
of plagioclase-felspar and pseudomorphs after some ferromagne-
sian mineral, together with rounded or oval vesicles, in a ground-
mass which varies considerably in character owing to different
degrees of decomposition.

In some specimens the felspar-phenocrysts are quite fresh, and
show extinction-angles corresponding to andesine and labradorite.
In other cases the felspar has become more or less turbid, owing to
conversion into an aggregate of minute crystals of mica and zoisite.
This gives a false appearance of strong refringency, and causes the
crystals to present a curious similarity to andalusite.

The ferromagnesian mineral is now represented by chloritic

712 MR. R. H. RASTALL ON THE GEOLOGY OF [ Noy, 1911,

pseudomorphs, and it was not found possible to determine its
original character with certainty. In some specimens it seems to
have been biotite, while in others the form of the pseudomorphs is
rather more suggestive of augite or hornblende.

The ground-mass varies a good dealin different specimens: in
the freshest of all it consists of minute lath-shaped erystals of
felspar, with grains of magnetite and flakes of chlorite and biotite.
One variety shows a considerable amount of quartz with the
felspar. In some specimens the structure of the ground-mass is
distinctly andesitic, with well-marked flow-structure indicated by
the arrangement of the felspars; while in the quartz-bearing variety
the ground-mass is very like that of the porphyrites, for instance,
of Canisp or the Cheviot Hills. In the more altered varieties,
on the other hand, the minerals of the ground-mass have been
converted into an aggregate of carbonates and micaceous substances,
with iron ores,

The vesicles contain a considerable variety of minerals, of which
the most important are pale-brown mica, chlorite, and epidote,
generally with some quartz, and occasionally tourmaline.

With regard to the petrographical character and classification of
this rock, it is difficult to make any definite statement. Owing to
the high degree of alteration, as shown by the abundance of
carbonates, epidote, and chlorite, it is quite evident that chemical
analysis would be not only useless, but misleading. Judging from
the characters of such minerals as are still determinable, the rock
appears to have been originally either a lava or an intrusion of
intermediate composition. Some specimens might be described as
typically andesitic in character, and the vesicular structure which
is so notable and conspicuous affords strong presumptive evidence
in favour of extrusion, or at any rate of intrusion under a somewhat
thin covering of rock. On the other hand the form of the mass is
difficult to reconcile with the supposition of a lava-flow, and is
much more strongly suggestive of an intrusion. Owing to the high
grade of the subsequent dynamic metamorphism, it is impossible to
determine whether or not the surrounding sediments have under-
gone any contact-metamorphism. The question must therefore be
left an open one, and the rock may be provisionally described
as porphyrite or andesite.

VI. Tae Orrrevite-Rocks or WaAat Kxoor.

When they are followed towards the east, the general character
of the Malmesbury rocks is seen to remain very uniform: although,
owing to the narrowing of the outcrop, the lower grits become less
conspicuous.

About 12 miles east of Worcester, the Coos River cuts through
the mountains in a narrow gorge called Waai Kloof, and near the
mouth of this gorge is an exposure of a very interesting rock. The
prevailing ao08 of this district is a highly crushed and slicken-
sided grit of uniform character, and presenting few points of
interest ; but in a small cultivated field, forming an expansion of

Vol. 67.] WORCESTER, ROBERTSON, AND ASHTON (CAPE COLONY). 7138

the gorge near its mouth, and close to the base of the Table
Mountain Sandstone, there is a narrow band of different character.
This is considerably harder than the rest, and forms a con-
spicuous ridge in the middle of the field. This ridge is about
30 yards long and perhaps 15 feet high, and is composed of thick
slabs of rock with their bedding (or schistosity) dipping steeply
southwards. This rock weathers in a peculiar manner, forming
smooth rounded surfaces with a high polish, and is locally known
as the Olifants Klip, or Elephant Rock. The same rock can also be
traced on the other side of the Coos River, just below the Table
Mountain Sandstone, and at this point it is highly disturbed. As
before mentioned (p. 707), what appears to be a much decomposed
representative of this band is to be seen in the Hex-River Pass ;
and this observation is of much importance, since, if this really is
the same band, an important clue is afforded as to the relation-
ship of the rocks of the Malmesbury Series at these two widely
separated points. According to this, the ottrelite-rock probably
forms a member of the lower division of the Malmesbury Series,
and it appears to lie to the north of the axis of the principal
anticlinal fold, as indicated in the section (fig. 1, p. 705).

A small number of specimens of the prevalent rock of this
district were collected, and they were found to be for the most part
somewhat crushed and slickensided grits of moderate to fine
texture, consisting of angular and subangular fragments of quartz,
in a rather schistose ground-mass of white mica and minute grains
of quartz. The edges of the larger quartz-grains are usually more
or less corroded, and in some specimens the characteristic sutural
structure of a quartzite can be discerned. ‘There is here evidence
of a high grade of dynamic metamorphism. These rocks do not
differ in any essential character from the grits in the Hex-River
section.

A considerable number of slices was cut from the rocks of
Olifants Klip, but all of them showed very similar characters, and
they may all be included in one general description [9466-67].

The principal minerals of this rock are quartz, white mica, and
ottrelite. In most specimens the rock may be described as composed
of more or less rounded grains of quartz of obviously clastic origin,
sometimes compound grains or minute fragments of quartzite ;
along the planes of schistosity lie in great abundance flakes of white
mica, somewhat fibrous in character and often curved and contorted.
In some cases there is a development of strain-slip cleavage. Scat-
tered through this ground-mass, with a distinct tendency to aggre-
gate in certain bands, are a large number of crystals of ottrelite,
measuring up to 1 millimetre in diameter. They usually are
roughly hexagona]. or rounded plates, thin in proportion to their
diameter, so that sections normal to the basal plane show a
prismatic form. The edges of the crystals are very irregular, and
consequently prismatic sections never show any termination, but
are rather fringed at the ends.

The colour of the crystals is to the naked eye very dark blue or

714 MR. R. H. RASITALL ON THE GEOLOGY OF [Nov. 1911,

black, and in thin sections a greenish-blue or bluish-grey. The
pleochroism is fairly strong, considering the paleness of the colour:
the usual tints being greenish-blue for rays vibrating nearly parallel
to ¢ 001, and very pale grey or colourless for rays vibrating normal
to this. The crystals are optically positive, and the absorption
scheme may be expressed as follows: a=b>rc. The extinction is
oblique, cAz = about 9°. A peculiar form of twinning is con-
spicuous, so that the usual prismatic sections appear to be divided
into four portions, of which opposite diagonal pairs extinguish
simultaneously. The refractive index is fairly high and the bi-
refringence rather weak. All these characters agree with those ot
ottrelite. |

This rock may be defined in general terms as an ottrelite-schist ;
and it is highly probable that, in this case at any rate, ottrelite
is a product of dynamic metamorphism, since there is no evidence
of any contact-action in this neighbourhood. The rock shows a
strong resemblance to the typical rocks of Ottré in the Ardennes.

VII. Tue Ropertson District.

In general structure this district closely resembles the neighbour-
hood of Worcester, but here aslight element of variety is introduced
by the occurrence of a large mass of granite in the Malmesbury
Series. This mass of granite forms a group of hills, of which the
highest rises to an elevation of just over 3000 feet, a height con-
siderably greater than that attained by the sedimentary rocks of
that series. As we shall see later, the presence of this mass of hard
rock has produced a considerable deviation in the general direction
of the Worcester-Swellendam Fault, and this gives rise to a question
of great interest: namely, what is the exact nature of the relations
between the dislocation and the granite mass ?

In this district, just as near Worcester, we can divide the country
topographically into three regions’: (1) the great escarpment of the
Table Mountain Sandstone, here rising to nearly 6000 feet, and
forming the range of the Langebergen ; (2) the narrow strip of
Malmesbury rocks forming foot-hills to the mountain-range ; (3) the
region south of the great fault, which here forms a district of some-
what more varied topography than farther west. It comprises a
hilly region about Roode Berg and Gorees Hoogte, composed of
highly folded beds of the Cape System ; another hilly region to the
west of this, extending from Lang Vley to Nuy, mostly composed of
Dwyka Conglomerate and Ecca Shales; and a level or gently
undulating district east and south-east of Robertson, which seems
to consist for the most part of Enon Conglomerate.

The highly-folded Cape rocks on this side of the fault present
some remarkable features: they are bent into a series of rather
steep anticlines and synclines, but the most striking feature is that
the axes of these folds are almost exactly at right angles to the
direction of the great fault, which is parallel to the strike of the Cape
rocks in the Langebergen. From the point of view of the physio-

Vol. 67.] WORCESTER, ROBERTSON, AND ASHTON (CAPE CoLoNY). 715

erapher, another interesting feature is that, broadly speaking, the
anticlines form hills and the synclines valleys, contrary to what is
usual in folded regions. The Breede River cuts through an anti-
clinal hill about 4 miles west of Robertson, and in the gorge thus
produced some magnificent examples of folding on a large scale may
be observed both from the road and from the railway. In general
terms, it may be said that throughout this district the most elevated
ground consists of Table Mountain Sandstone and Witteberg
Quartzites, whereas the Bokkeveld Beds, being softer, form low
ground, and are often completely hidden by alluvium.

(1) The Malmesbury Rocks.

The rocks composing the Malmesbury Series in the district near
Robertson are very similar in general character to those of
Worcester; hence it is hardly necessary to describe their lithological
character in detail. They consist of a fairly uniform series of rather
fine grits and slates of a grey, greenish, or silvery colour when
fresh ; but, when much weathered, as is commonly the case, the
prevailing tint is a pale olive-brown. A bed of dolomite is seen at
Keur Kloof, about a mile north of Robertson, and another outcrop
of what is (in all probability) the same bed occurs in the road which
runs up the valley of the Hoops River, about 3 miles to the east.

The outerop of the Malmesbury rocks is here rather narrow,
averaging not more than a mile in width, except in the neigh-
bourhood of the granite mass, where it expands greatly, as seen
on the map. There are not sufficient data available to show to
which division of the series, as defined at Worcester, they should be
assigned,

In the neighbourhood of ie granitic intrusion of Wolve Kloof
the Malmesbury rocks are highly disturbed, but there is little or no
evidence of thermal metamorphism, although the actual contact of
the granite and sediments is exposed in several places. Along the
footpath which runs from Robertson to Wolve Kloof, near the
ruined water~mill at the entrance to the Kloof, there is a rapid
alternation of granite and apparently unaltered sediment, each of
which occurs along the path in patches a few yards wide. The
junction is evidently very irregular, with tongues of granite pro-
jecting into the slates. The latter are much sheared, but no
development of contact-minerals can be seen. A short distance
north-east of this point, at the top of the first cultivated field on
the side of the hill, is an exposure of rock of the phyllite-gneiss
type, evidently a crushed granite-dyke.

The succession of the Malmesbury rocks is seen most completely
along the road which leads up the valley of the Hoops River. From
Robertson as far as the river this road runs over Witteberg Slates
and Enon Conglomerate, both of which are well exposed in several
cuttings. Near the drift over the river, about 2 miles east of
Robertson, there are not many exposures; but a few yards beyond
the drift there is by the roadside a patch of typical Malmesbury

Orde Grace NO, 200, 3¢

716 MR. R. H. RASTALL ON THE GEOLOGY OF [Nov. 1911,

Slate, with a dip totally different from that of the Witteberg Beds.
Hence it is certain that the main fault must cross the river very
near the drift. At this point the road turns northwards and runs
parallel with the river for some miles, over a monotonous series of
grey sandy flags and mudstones, with occasional bands of silvery slate
and soft olive-green shale. The strike of these rocks is about west
10° south, and east 10° north, and the dip is always southwards
at an angle varying from 20° to 50°. About half a mile north of
the drift is the band of dolomite previously mentioned (p. 715), and
close to it is a rather coarse grit, as also a very peculiar schistose
rock containing large blocks of black vein-quartz, which impart to
it a sort of augen structure. This appears to be a crushed con-
glomerate, since the blocks of quartz are certainly of detrital origin.
This may be compared with the conglomeratic band seen close to
the marble-yuarry at Worcester, and it is just possible that they are
the same, since in each case the conglomerates occur in conjunction
with a caleareous band.

Throughout this series cleavage and jointing are very conspicuous
in the finer beds, while the gritty beds show these structures less
perfectly. Vein-quartz is abundant almost everywhere, and always
shows a peculiar blue-black colour. The quartz-veins were evidently
injected before the final foliation of the Malmesbury rocks.

Calecareous beds occur in several localities in the neighbourhood
of Robertson. The most important of these are on the farm
Dassies Hoek, where they are associated with black graphitic
shales.‘ Beds of dolomitic limestone are also seen on the Hoops-
River Road, and in Keur Kloof, north of the town; the latter
occurrence was at one time worked for lime-burning. It is a dark
bluish-grey rock, which weathers in a peculiar manner, becoming
covered with a thick, pulverulent, white crust. A rough quanti-
tative analysis of this rock showed the presence of 10 per cent. of
matter insoluble in hydrochloric acid, 6 per cent. of ferrous car-
bonate, and 37 per cent. of magnesium carbonate, so that it is
correctly descr bed as an impure gritty dolomite.

(2) The Granitic Intrusion of Wolve Kloof.

This large mass of granite has a roughly oval form, and measures,
as at present exposed, about 43 miles from north to south and
24 miles from east to west. It forms conspicuously high ground,
and its central portion rises to a height of over 3100 feet above the
sea. ‘The exact outline is difficult to determine, owing to the rugged
nature of the ground and a thick covering of vegetation on the
lower slopes. By far the best section is seen in Wolve Kloof, a deep
and narrow gorge formed by the Nels River, which cuts through
the granite for a distance of about 15 miles. ‘The precipitous sides
of this gorge are formed of smooth rounded surfaces of granite ,

+ A.W. Rogers & A, L. Du Toit, ‘Geology of Cape Colony’ 2nd ed. (1909)
p: 24,

Vol. 67.] WORCESTER, ROBERTSON, AND ASHTON (CAPE CoLony). 717

presumably curved joints, but presenting a strong deceptive resem-
blance to the curved ‘ boiler-plate slabs’ so characteristic of igneous
rocks in glaciated regions. ‘The rock is much weathered, and it is

somewhat difficult to obtain really fresh material.

Sections were cut from specimens collected from different parts
of the mass, but all are very similar, the chief difference consisting
in the presence or absence of phenocrysts of felspar, which are never
very abundant and sometimes wanting. Another difference les in
the amount of foliation: the central portion, especially in Wolve
Kloof, is free from foliation, whereas near the margin a gneissose
structure is often conspicuous. In certain parts aplitic veins are
fairly abundant, but otherwise the rock shows little variation.

The granite is a rock of moderately coarse grain, of a prevailing
bluish-grey colour when fresh, with scattered phenocrysts of white
felspar measuring up to 1 inch in length. The principal minerals
are quartz, felspar, and mica, with accessory iron-ores and sphene.
The quartz, which was the last mineral to crystallize, forms large
irregular crystals, much cracked and shattered, and exhibiting
conspicuous strain-shadows. Several varieties of alkali-felspar can
be recognized, including orthoclase, microcline, microcline-perthite,
and microperthite. These are usually quite elear and fresh, whereas
the plagioclase, which occurs in subordinate amount, is distinctly
turbid, and for the most part converted into an aggregate of white
mica and zoisite. The plagioclase shows very small extinction-angles,
corresponding to oligoclase. The soda-molecule of the plagioclase has
evidently given rise to soda-mica, while the lime-molecule has formed
zoisite. The principal coloured mineral is an olive-brown biotite,
which is usually much chloritized and then green in colour. It is
full of inclusions, some of which are epidote, while others consist
of black opaque iron-ore surrounded by a ring of sphene. This
latter fact suggests that the iron-ore may be ilmenite, which has
given rise to sphene as a reaction-product. A few large original
sphenes are also present. Some of the bigger flakes of muscovite
which occur in places may possibly be of primary origin, but the
greater part of this mineral is undoubtedly derived from plagio-
clase-felspar. Some specimens of the granite, especially the more
porphyritic examples, show a strong tendency to micrographic inter-
growths of the quartz and felspars of the ground-mass [9470-71].

The aplite forms narrow veins and strings penetrating the granite
in all directions, but its distribution is somewhat restricted. It
consists of quartz and a great variety of felspars, all of alkaline
composition, with only the merest trace of biotite. Sphene and
small garnets are occasionally present. In this rock the quartz has
commonly crystallized before the felspar. No notable difference of
composition can be detected between the normal granite and the
aplite ; the variation is chiefly a matter of texture, though the aplite
appears to be of somewhat more acid character [9468-69].

Since the inner parts of the granite mass, where cut through
by the Nels River in Wolve Kloof, show no foliation, while the
outer portions are much crushed and shattered, it is clear that the

ao 2

rey
718 MR. R. H. RASTALL ON THE GEOLOGY oF _ [Nov.1og11,

intrusion took place before the final foliation, and that the great
size of the main mass protected the interior from crushing, while
the margin and the peripheral dykes were strongly foliated. Thus,
even at this early stage, before the deposition of the Cape rocks, this
intrusion acted as a horst, and that fact has some bearing on the
problem of the later faulting.

VIII. Tar Cars anp Karroo Rocks or WorcESTER
AND ROBERTSON.

For the purposes of the present paper, it is unnecessary to enter
into a lithological description of the rocks of these two series.
They are quite normal in character, and call for no special remark.
Perhaps the most noteworthy feature is the entire absence of any
exposure of the Bokkeveld Series in the neighbourhood of Worcester,
on the north side of the Breede River. Since typical Witteberg
shales and quartzites are seen in the banks of the river south of
Goudini Road Station, and also for some distance in the neighbour-
hood of Brand Vley, and these beds dip north, it is possible that the
whole of this great alluvial flat is really underlain by Witteberg
and Karroo beds, although it is frequently assumed that such large
valleys are excavated out of Bokkeveld beds, which, as a matter of
fact, 1s generally the case.

Somewhat farther south, over a great area stretching from Brand
Vley and the Hoeks River on the west to some miles east of Lang-
Vley Station, the ground is occupied by a great development of
Karroo rocks, with a strip of Enon.Conglomerate on the north.
The rocks of the Karroo Series are here quite normal, and just
like those of the main area of the Karroo itself. The Dwyka
Conglomerate is very thick, but the boulders are mostly small.
Good specimens of the whole series can be obtained near Lang- Vley
Station; and close to the station in the Ecca Shale is a bed of
anthracite, which is now being worked under the name of graphite.

The sandstones of the Ecca Series are exposed at several points
near Worcester. In the goods-yard at tle station is a very fine
exposure showing Enon Conglomerate resting on Kcca Sandstone ;
and the same sandstone can be seen in many places, in the floors of
the sluits formed by heavy rains in the brick-earth flat north of the
station. About 3 miles west of Worcester Station is a curious
small conical hill, by the side of the railway, which has been
quarried, and this also consists wholly of Kcca Sandstone. Here
the rock strikes north-north-west and south-sonth-east, and the dip
is about 20° to the east. Im all these exposures the dip of the
sandstone is either more or less parallel to the fault or towards it,
which is of course unusual on the downthrow side. ‘The rock is
everywhere very uniform, and consists of a fine-grained greenish
or yellowish sandstone with obscure plant-remains, among which
sufficient forms have been recognized to establish the age of the
formation, at any rate in a general way, as Kcca Sandstone. This
sandstone probably underlies a good deal of the alluvial flat of the
Breede Valley south of Worcester,

Vol. 67.] WorcesvER, ROBERTSON, AND ASHTON (CAPE Cotony). 719

Small isolated patches of Dwyka and EKeca rocks are also seen
close to the town of Robertson, and especially along the railway
and in the low hills immediately north of it. ‘There is a good
exposure of typical Dwyka Conglomerate near the water-mill to
the north-west of the town, at the mouth of Wolve Kloof. These
rocks are normal, and require no further description.

IX, Tue Enon ConGLoMERATE.

One of the most important formations for the purpose of the
present investigation is the Enon Conglomerate. It is unnecessary
here to recapitulate the evidence on which this deposit has been
correlated with the marine Cretaceous strata of the Uitenhage
Series: this correlation may be taken as fully established. Within
the area here dealt with, almost all the deposits of this age are of
a terrestrial and torrential character, and were apparently formed
under conditions very similar to those now prevailing in the
district. At any rate, it is sometimes difficult to distinguish the
more weathered portions of the Enon Conglomerate from the coarse
gravels of recent and subrecent origin which cover such great areas
in the valleys and lower parts of the district. A careful examination,
however, shows that the character of the pebbles is different: that
is to say, they have been derived for the most part from different
formations, as will later be explained in detail.

In the district under consideration there are three disconnected
patches of Enon Conglomerate: a small one north-west of Wor-
cester, a larger one running more or less along the course of the
Nuy River, and a very large spread stretching from Robertson to
Ashton. This outcrop is roughly oval in shape, and measures
about 15 miles in length by 6 miles in width.

The Enon Conglomerate is well seen at Worcester Station,
resting unconformably upon Ecca Sandstone. The pebbles here
average about 3 inches in diameter, and are embedded in a reddisi
sandy matrix, which appears to be much weathered. ‘The pebbles
are almost wholly composed of hard, dark grits. Much fresher
material can be obtained from an excavation recently made close
to the new reservoir-dam, north-west of the town, and many
blocks have been used in the construction of the dam. ‘he con-
glomerate is here extraordinarily hard, and the pebbles are on the
average somewhat smaller, so that it can be dressed into hand-
specimens. ‘The cement is partly ferruginous and partly calcareous.
The conglomerate is also exposed in many places in the sluits before
mentioned, but is here much weathered. ‘The pebbles are every-
where almost exclusively hard, dark-green, grey, and red grits
and rocks of a somewhat jaspery appearance. It is noticeable
that the pebbies are very frequently bent, fractured, faulted, and
indented, indicating pressure, as in the Polygenetic Conglomerate
of Cumberland, to which this rock shows a striking resemblance.
It is highly probable that most, if not all, of the rounded gravelly

720 MR. Rk, H. RASTALL ON THE GEOLOGY OF [Nov. 1911,

hills north-west of Worcester really consist of Enon Conglomerate,
with perhaps a thin coating of recent gravels ; but, in the absence of
exposures, it is impossible to decide this point with certainty, owing
to the before-mentioned difficulty of distinguishing between the
weathered Enon and the newer gravels.

Prof. E. H. L. Schwarz’* has mapped and described as Enon
Conglomerate a patch of gravel on the farm Lange Kloof (Geol.
Surv. Map, Sheet 4), east of the Hex River; he refers to it as
‘an exposure of gravel, evidently very old, but of which the
pebbles are made of slate.’ Unfortunately, owing to bad weather
and floods in the Hex River, I was unable to visit this interesting
and important exposure; but, judging from a comparison of the
published description with what is seen elsewhere in the neigh-
bourhood, I feel the gravest doubts whether this gravel is of
Cretaceous age, as claimed by Prof.Schwarz. The absence of slate
in the conglomerate at Worcester is noteworthy, and it is improbable
that there would be so complete a difference of composition in
So short a distance (less than 5 miles), especially as the Enon
Conglomerates of Robertson and Ashton (30 and 40 miles away
respectively) are exactly like those at Worcester, and contain
no slate.

The small patch of Enon Conglomerate west of Robertson calls
for no special remark, but in connexion with the large expanse of
conglomerate east of the town a most important question arises.
On the map of the Geological Commission, on the farms De Hoop
and Aasvogels Nest, the conglomerate is shown, doubtfully, over-
lapping the fault, and resting directly upon Malmesbury Beds. If
correct, this observation fixes the age of the fault as between
Keea and Enon, a result diametrically opposed to my observations
elsewhere. JI therefore examined this region most critically and
carefully, and came to the conclusion that this mapping is unjustified
by the evidence. The ground is very obscure, and there are no
exposures in the form of excavations.

The Malmesbury rocks here form fairly high ground, with a
steep slope, in fact a kind of escarpment, and on the next farm,
Klaas Voogds Rivier, a curious wedge of Witteberg Beds comes in
along the fault, and makes a conspicuous feature in the form of a
rocky ridge. On De Hoop and Aasvogels Nest low rounded hills of
gravel lie at the foot of the escarpment, and the northernmost of
these certainly lie to the north of the fault. But these hills do not
all consist of the same kind of material: the southern hills are un-
doubtedly Knon Conglomerate, but the hills north of the fault-line
consist of quite different material, without the characteristic. red
pebbles of the Enon Conglomerate. The last hill of all, at the foot of
the escarpment, is different again, being composed of large blocks

1 *Geological Survey of the Divisions of Tulbagh, Ceres,-& Worcester’
10th Ann. Rep. Geol. Comm. Cape Colony, 1905, p. 289.

Vol. 67.] WORCESTER, ROBERTSON, AND ASHTON (cAPE cotony). 721

of Table Mountain Sandstone, which is not seen in the southern
hills. Itis quite clear that the material of which these hills are
composed has been derived from at least three sources ; and, from
a careful examination, it appears certain that the gravels are
successively newer towards the north. Fig. 2 shows the interpre-
tation of the section which I adopted, after a critical examination in
company with Dr. Melle, of Robertson, who is well acquainted with
the geology of the neighbourhood. Of course, in this section the
exact position of the fault is hypothetical, but compass-bearings of
points where it is known give the general position with fair accuracy.
It must come somewhere under the gravel-ridge marked G, which
obviously overlies the Enon Conglomerate, and is overlain in turn
by the coarse breccia B.

Fig. 2.—Diagrammatic section through the southern part of the farm
De Hoop, 3 miles east-north-east of Robertson.

Position of
Worcester Fault

[M.M.=Malmesbury Slates. W-—Witteberg Slates. E.C.=Enon Conglo-
merate. G=Recent gravel. B=Scree-breccia, with large blocks of
sandstone. |

I conclude, therefore, that the Enon Conglomerate does not
extend over the line of the fault on to the Malmesbury Beds, but
is cut off by the fault on the northern side.

It is of interest to note that the Enon Beds of this area are not
wholly conglomeratic ; hut near Klaas Voogds Station there is a
development of fine grey or white sandstone, which shows some
approximation to the more normal marine Cretaceous deposits of
the Uitenhage district. This is probably the westernmost point to
which the marine Uitenhage facies has been traced. Unfortunately,
no fossils were found here.

X. Tae Asuron Distrrict.}

Ashton Station, on the New Cape Central Railway, lies about
12 miles east of Robertson, and from it an important road leads
through Kogmans Kloof to the town of Montagu, which lies on
the other side of the Langebergen. The general character of the
country is very similar to what is seen farther west, but on the
whole the topography is simpler.

The belt of Malmesbury rocks is here much narrower, being not

1 See Cape Colony Geol. Surv. Map, Sheet 2,

722 GEOLOGY OF CBRTAIN DISTRICTS OF cAPE conony. [Noy. rgrt.

much more than half a mile wide where cut through by the Kog-
mans River, which affords a very good and nearly continuous
section. In the right bank of this river, near Ashton Station, is

Fig. 3.—Geological map of the district round Montagu and Ashton.

.
.
ote
Ss

=
W—T T—I-E-B-E RG
EZ

eg ND ee ee Maless

[The geological boundaries in this map, with the exception of those in the
immediate neighbourhood of Montagu and Ashton, are copied
from the published map of the Geological Commission of the Cape Colony,
Sheet 2.—M.=Malmesbury Series. |

a section of Enon Conglomerate, which is by far the largest and
clearest in the whole district. Some valuable information was also
obtained from a well sunk by Mr. J. O’Connor, of Ashton, on the
west of the Kogmans River, by the side of the main road to

ie
omy = 2,
= SEES
S geee™—
a
ak
eS > a
8 ye
= = :
S
S >
R eS
ii =
xy
— Ce
S epee): \ SS
Ht ae _
Ss a
~
= &
S n
Ss
a
aoe
a)
A
= =
» SS
sj 8
= BNS
ae a
a ES
8
ty
= ay

VV

a

Witteberg Beds

ig. 4.—Diagrammatic section along the banks of the Kogmans River.

Conglomerate

[T.M.S.=Table Mountain Sandstone. |

Robertson. This well passed through
about 60 feet of Enon Conglomerate,
and a fine typical collection of pebbles
could here be examined in detail.

The general structure of this district
is simple, but of considerable interest ;
and its principal features can be made
out from an inspection of the small map
(fig. 3, p. 722). At Kogmans Kloof
there is a noticeable kink in the general
trend of the Langebergen Range, and
this kink is accompanied by what
appears to bea thrusting forward of the
Cape rocks towards the south-west. On
the right bank of the river, just below
the mouth of the pass, the Enon Con-
glomerate appears to be in contact with
Table Mountain Sandstone; but, un-
fortunately, it is impossible to determine
what underlies the conglomerate at
this point. ‘There can, however, be no
reasonable doubt that here, as elsewhere,
it rests on Witteberg Beds: this question
will again be referred to later. The
position of this mass of Table Mountain
Sandstone is doubtless due to two
nearly parallel faults, the more important
running nearly along the line of Kog-
mans Kloof towards Montagu, while
the second follows closely the line of
the upper part of Wild Paarde Kloof
and crosses the Keisies River to the
north-west of the farm Uitvlugt. These
are tear-faults, and between them a
block of Table Mountain Sandstone about
2 miles wide has been pushed nearly
amile to the south-west. This faulting
is of earlier date than the Enon Con-
glomerate. .

The banks and bed of the Kogmans
River, from near Ashton Station to the
mouth of Kogmans Kloof, afford a very
clear section in which the relations of
the different rock-groups can be made
out with certainty. This is illustrated
by fig. 4. The Enon Conglomerate,
when best exposed for a thickness of
about 40 feet, consists of large rounded
and subangular boulders embedded in
a red sandy matrix: it shows distinct
bedding, with a gentle dip to the south.
On the left bank of the river it is
clearly seen lying on Witteberg Beds,

724 MR. R. H. RASTALL ON THE GEOLOGY OF (Nov. 1911,

which are here reddish shales with occasional bluish grit-bands,
intensely folded and contorted. This folding is of a very peculiar
character, since many of the folds are in the horizontal position,
with their axial planes vertical. It is evidently impossible
to represent this in a diagram. Sometimes, for considerable
distances the strike of the beds is nearly north-east and south-
west, that is, at right angles to the normal strike of the district ;
but the general trend appears to be north-west and south-east.
In the arches of the anticlines are occasional patches of crush-
breccia. The total width of the outcrop of the Witteberg Beds in
the river is about 1000 yards.

The exact position of the great fault between the Witteberg and
the Malmesbury Beds is very clearly indicated, and the strikes of
the two series are quite different. The structure of the Malmes-
bury Series is much simpler, and the dips more uniform ; the folds
which can occasionally be seen are not of much importance. The
rocks of this series are for the most part silvery or blue slates,
weathering yellow, with occasional grit-bands. The width of the
outcrop of Malmesbury Beds is here about 800 yards, and at one
point a fault is very clearly seen in the middle of the series.

The junction with the Table Mountain Sandstone is almost
vertical, and the lowest bed of the latter, about 4 feet thick,
appears to be a basal conglomerate of quartz-pebbles, which has
been afterwards infilled with vein-quartz. It presents a strong
superficial resemblance to the bankets of the Rand, and has been
unsuccessfully prospected for gold. The Table Mountain Sandstone
itself is here of the usual character, and calls for no comment.

This section is of especial interest, since it displays very clearly
and in a compact form a typical series of the rocks of this district.
Incidentally it may be mentioned that the published map of the
Geological Commission of the Cape of Good Hope, on the scale of
3? miles to the inch, is incorrect at this point, since it shows the
river flowing over Malmesbury Slates and Enon Conglomerate only,
whereas the Witteberg Slates are seen in the banks of the stream
for nearly 1000 yards. It appears, therefore, that there is actually
a narrow tongue of Witteberg Beds running between the outcrop
of the conglomerate and the fault, across the stream ; and the Enon
Conglomerate is here not cut off by the fault, although it comes
against 1t a little farther north.

The fine exposure of Enon Conglomerate on the right bank of
the river forms a prominent cliff about 40 feet high, of which the
uppermost 10 feet or so is recent alluvium, consisting of yellow
gravel with very big boulders of Table Mountain Sandstone up toa
cubic yard in bulk. About 30 feet of the conglomerate is exposed,
consisting of boulders measuring as much as 1 cubic foot, embedded
in a reddish sandy matrix. Bedding is distinctly shown, and the
dip is about 10° southwards. The boulders in this conglomerate
consist exclusively of sandstones and grit, mostly resembling those
of the Witteberg and Ecca Series; and, despite the most diligent
search, no fragments of Malmesbury rocks could be found.

Vol. 67.| worcEsrER, ROBERTSON, AND ASHTON (CAPE COLONY). 725

A careful examination was also made of a well, sunk by
Mr. J. O'Connor about half a mile west of Ashton Station, by the
side of the main road to Robertson. ‘The following section was
compiled from personal inspection, and from data supplied by

Mr. O’Connor :—
Thickness in feet.

SOIL; Clay, tO! ap. cases-5ee dn af PER ee 30
EVea Tee eee P Ly CIN wc ce oceans Lon sks on'venaesn 25
FOIE MEM acne cece esac creat a tte tee Be eee a'e oe 9)
Binon Conglomerate 0... chicses-sacecsiessssedeasee 60

The recent deposits of soil and clay are here of extraordinary
depth, no less than 60 feet being passed through. ‘The lowest 5 feet
of this consists of a bed of big boulders, chiefly of Table Mountain
Sandstone, well rounded by water-action. A very large pile of
pebbles from the Enon Conglomerate was carefully examined.
They range up to 18 inches in diameter, and the largest came
from the bottom of the well. Abundant specimens of Dwyka Con-
glomerate were observed, while the blocks of sandstone closely
resemble the grit-bands in the Witteberg Series, and are quite
unlike the Table Mountain Sandstone. It is an observation of the
utmost significance that the Enon Conglomerate of this neighbour-
hood contains no fragments of Malmesbury rocks, and this statement
is fully confirmed by Mr. O’Connor, who has an intimate know-
ledge of all the rocks of this neighbourhood. There is also some
evidence that boulders of Dwyka rocks are more abundant below,
and those of Witteberg rocks above.

XI. Gunrerat ConcLusions.

The dominant tectonic feature of Cape Colony is the occurrence
of conspicuous lines of folding, which are very clearly indicated by
the outcrop of the rocks of the Cape System. Over an immense
area in the centre and north of the Colony the rocks of the Karroo
System are horizontal; but, towards the south and west, they begin
to show increasingly steep dips, and at the margin of the outcrop
they are very highly inclined along with the Cape rocks. In the
south the two systems are apparently conformable, but towards the
north there is a conspicuous overlap of the Karroo System. The
markedly rectangular form of the south-western corner of the
Karroo outcrop is intimately connected with the direction of the
principal lines of folding. These are divided into two well-defined
sets: near the west coast the trend-lines run north and south,
while near the south coast they run east and west. ‘These are
called by Dr. Rogers the Cederbergen and Zwartebergen Series
respectively.

These two sets of folds come together in the neighbourhood of
Worcester and Robertson, and it is necessary to consider the nature
of their junction or syntaxis. ‘The matter is further complicated
by the occurrence of the great Worcester-Swellendam Fault, which
cuts obliquely across the syntaxis, and has brought down a small
area of Karroo rocks on its southern, or downthrow side. It is

726 MR. R. H. RASTALL ON THE GEOLOGY OF [Nov. 19rf,

evidently, therefore, of the first importance to determine, if possible,
the age of this fault.

Furthermore, a careful study of a geological map of the region
shows that the two sets of folds may be regarded as spreading out

Fig. 5.—The dominant trend-lines of the south-western part of

Cape Colony.

selene Lie al EE ES enon Ss
Worcester Fauit,] Fe Tt ORIN Tey eS AI BOs CHOY LOMO nea yeh iC os

,
ww el4 oe

Sel

| GRA
cd

>
( .
\

[The dotted areas are occupied

by Karroo Rocks; een, SK /
the pre--Karroo being left blank ] SSC) Agulhas

5 100
Seale ee Miles

in a somewhat fan-like manner from a point or region situated
somewhere in the neighbourhood of Somerset West, on the east side
of False Bay: if a line is drawn from this point in a north-easterly
direction, the folded mountain-chains are arranged more or less
symmetrically with regard to it, and the Worcester Fault cuts it

Vol. 67.] WoxcHsTuR, ROBERTSON, AND ASHTON (CAPE COLONY), 727

approximately at right angles. It is also noticeable that the fault is
curved, running nearly parallel at either end to each of the sets of
folds, and changing its general direction from north and south at
one end to east and west at the other. From these considerations,
it is evident that the fault has a close genetic connexion with the
folding.

Although these two phenomena are obviously connected, it must
not be assumed that they are contemporaneous: in fact, such is
clearly not the case. From a study of the structure of the rocks
of the Cape System on either side of the Worcester Fault, there
can be httle doubt that the faulting is in the main later than the
folding, although it is probable from other considerations that no
long interval of time separated them.

The faulting is certainly later than the rocks of the Kcea Series,
since the Dwyka Conglomerate and Ecca Sandstone and Shale are
brought into contact with Malmesbury and Cape rocks. The question
next arises, whether the fault is or is not newer than the Enon
Conglomerate; and to this it is somewhat more difficult to give a
conclusive reply, since some of the evidence is not very clear. The
most important fact to determine for this purpose is whether or not
the Enon Conglomerate is cut by the fault, and as to this some
doubt has hitherto existed. There is no doubt that the fault forms,
in a general way, the northern boundary of the Enon facies of the
Cretaceous in this region’; but, on the maps of the Cape Geolo-
gical Commission, the conglomerate 1s mapped in places as just
overlapping the fault, apparently for a few hundred yards. This,
on the face of it, is improbable: if the present distribution of the
conglomerate is independent of the fault, it is unlikely that its
boundary would follow so closely the line of the fault for scores of
miles, and overlap it occasionally for a few yards only. There is
no real field-evidence for this interpretation, and the general form
of the patches of Enon Conglomerate is very strong presumptive
evidence in favour of their truncation on the northern side by the
fault, exactly in the same way as the Karroo rocks are truncated.
Hence, we may conclude almost with certainty that the Wor-
cester-Swellendam Fault is, at any rate in part, newer
than the Lower Cretaceous.

Another line of argument may also be pursued, namely, that
derived from the character of the blocks and pebbles of which the
Enon Conglomerate is composed. In the first place, so far as my
own most careful observations go, the Enon Conglomerate at
Worcester, Robertson, and Ashton does not contain pebbles of the
Malmesbury rocks. ‘The only possible exception to this is the
somewhat doubtful case described by Prof. Schwarz at Lange Kloof
near the Hex-River Pass, and as to this I am frankly sceptical,

1 Dr. Rogers & Mr. Du Toit consider that the Enon Beds of the Oudts-
hoorn region were formed in a different basin of deposition; see their

Geology of Cape Colony’ 2nd ed, (1909) p. 321,

728 MR. R. H. RASTALL ON THE GEOLOGY OF [Nov. 1911,

since it is obviously so different from all the other occurrences
in the neighbourhood. I paid especial attention to this point in
the exposures of Enon Conglomerate near Robertson and Ashton,
and was unable, after several prolonged searches, to find a single
piece of Malmesbury slate.

But a further point may also be put forward: the coarse grits and
quartzites of the lower part of the Table Mountain Series could not
be identified with certainty in the Enon Conglomerate. It appeared
to me, and to the local observers who were kind enough to assist
me, that all the blocks in the Enon Conglomerate could be referred
to the Witteberg and EKcca Series (including, of course, in this last
designation the Dwyka Conglomerate). This is an argument which
must not be pushed too far, since it 1s obviously impossible to state
dogmatically that every pebble of quartzite or of sandstone is Witte-
berg or Ecca Sandstone and not Table Mountain Sandstone. Still,
it may be safely asserted that the general facies of the pebbles in
the Enon Conglomerate led to the belief that the Table Mountain
Sandstone is not represented therein.

If these facts are admitted, we are at once led to an important
conclusion, namely: that at the time of the formation of
the Enon Conglomerate the Malmesbury Series and
the lower part of the Cape System were not exposed in
the district here investigated.

In order to appreciate the full significance of this conclusion, we
must now consider what were the conditions under which the Enon
Conglomerate was formed. It is obviously a torrential deposit,
composed of well-rounded blocks, embedded in a sandy matrix,
with occasionally, and especially in the higher part of the succession,
beds of a finer texture and sandy or marly character. This deposit
has evidently been formed under terrestrial conditions, and it is very
similar to the deposits now being formed, or which have recently
been formed, at the foot of the mountain-slopes of the region, and
especially where the larger streams cut through the ranges.
Reference has already been made to the difficulty of distinguishing
between weathered Enon Conglomerate and some of these recent
deposits, and their manner of formation must have been very similar.
When bedding is visible in the Enon Series, it is often evident that
the material came from the north, showing that at that time also the
high ground lay in that direction.

However, it appears improbable, from two independent lines of
argument, that the Enon Conglomerate was formed in exactly its
present position. In the first place, it has been shown that the
Enon Conglomerate has taken part in some, at any rate, of the move-
ment of the Worcester Fault, hence it must have been formed at
a higher level: and secondly, the materials of the conglomerate are
not of a character consistent with formation at the present level.

It may be suggested, then, that at the time of the formation of
the Enon Conglomerate a range of mountains existed in approxi-
mately the same geographical position as the Langebergen, but at a
higher level, so that it was composed of Witteberg and Karroo

Vol. 67.] WORCESTER, ROBERISON, AND ASHTON (CAPE CoLoNY). 729

rocks. These were undergoing rapid denudation, and the denuded
material accumulated at the foot of their steep southern slope, most
probably in disconnected basins, corresponding more or less to the
present distribution of the conglomerate, but of larger size.

In order to gain some idea of the height above the present level
at which this denudation and accumulation took place, we must take
into account the thickness of the Cape System. According to the
best authorities, the Table Mountain Sandstone is about 5000 feet
thick, the Bokkeveld Series 2500 feet, and the Witteberg Series
also 2500 feet. On the assumption that only Witteberg Beds were
exposed, the ground-surface must then have been some 7000 or
8000 feet higher than at present. This height need not necessarily
have been absolute height above sea-level, but may be referred to
some «arbitrary datum-line—for example the base of the Cape
System, which may then have been absolutely either higher or lower
than at present.

According to this view, then, the Enon Conglomerate resulted
from the denudation of a land-surface, possibly a mountain-range,
formed of Witteberg and Karroo rocks, while the underlying pre-
Cambrian rocks were not exposed. There is some evidence that
Dwyka Conglomerate is more abundant in the lower part of the
conglomerate, and Witteberg Beds in the upper part, thus indicating
a progressive uncovering of lower and lower beds; but on this point
much more work is needed before it can be regarded as established.
Then, after the formation of the Enon Conglomerate, the major
portion at any rate of the fault-movement took place, bringing Enon
Conglomerate in places into juxtaposition with Malmesbury rocks.
This fixes the age of the fault as post-Cretaceous.

The disposition of the minor lines of folding in the region to the
south of the fault is in favour of the view that a close connexion
exists between the folding and the faulting. North of the fault
the strike of the Cape rocks of the Langebergen is uniformly east
and west, and the dip is steeply northwards. South of the fault,
however, they are ridged up into a series of sharp anticlines and
synclines, with axes running approximately north-north-east and
south-south-west, and occasionally accompanied by parallel faults :
as, for example, west of Lady Grey. The trend-lines of these
structures are, therefore, nearly at right angles to the principal fault.
It appears, then, that when the region to the south of the fault sank
down, it also underwent a sort of lateral crumpling due to com-
pression.

Let us now turn to a consideration of the events which succeeded
the formation of the Enon Conglomerate. As we have already seen,
the evidence suggests that the conglomerate was formed on an old
land-surface, composed of Ecca, Witteberg, and Bokkeveld rocks,
Then, as a result of earth-movement, or possibly on account of a
release of pressure, subsidence took place along a fault-line (which
had probably been already initiated), resulting in the formation
of the great Worcester-Swellendam Fault, This fault must be

730 MR. R. H. RASTALL ON THE GEOLOGY OF [Nove i6 ti,

regarded as a fracture and depression occurring in the triangular area
between two sets of folds at right angles one tothe other. A very
similar phenomenon is the well-known area of the Warm Bokkeveld,
which is also a depressed region, and immediately north of it is a
smal] patch of Karroo rocks, let down by a fault on the north-
eastern side. This fault runs parallel with the Worcester Fault,
and is probably due to the same set of causes.

These folds are obviously due to lateral thrust, since they are
clearly asymmetric, but it is still a matter of discussion from which
side the greater pressure came. Prof. Schwarz’ has put forward
the view that the folding of these ranges is due to the intrusion of
the vast sheets of dolerite in the Karroo System, thus implying that
the maximum pressure came from the interior. This idea is in-
genious, but (so far as we know at present) inconsistent with the
field evidence.” The general structure of the region and the dis-
position of the folded chains can be much more easily explained on
‘the supposition of pressure acting from the exterior towards the
interior, and consisting of two sets of thrusts:—one towards the
north, which produced the east-and-west folds of the Langebergen
and other parallel ranges, the Zwartebergen folds of Rogers; the
other towards the east, giving rise to the ranges of the west-coast
region, the Cederbergen folds. ‘These two sets of-thrusts interfered
mutually where they came in contact, in the south-western corner
of the Colony, thus producing the fan-shaped arrangement of
mountain-chains which is so characteristic a feature. It appears
that this fault was formed subsequently to the principal period of
folding, and it probably cecurred when the pressure was released to
a certain extent, thus allowing of a great subsidence.

This final, post-Enon, movement was evidently accompanied by
considerable earth-pressure, since the pebbles of the conglomerate
are commonly fractured and indented, and this process presumably
took place concurrently with the formation of the fault.

To sum up: the dominant features of the geology of this region
are :—

(a) The conspicuous folding, of post-Karroo age, in part pre-
Cretaceous: this led to the formation of mountain-chains in two
sets, east-and-west and north-and-south respectively, with a syn-
taxis in the south-western corner of Cape Colony.

(b) A post-Cretaceous period of movement, which resulted chiefly
in a great subsidence to the south of a fault-line cutting obliquely
across the syntaxis; accompanying or preceding this were nmiunor
lines of crumpling on the downthrow side of the fault, leading to
the formation of subsidiary folds striking north-east and south-
west, or thereabouts. It is impossible to say with certainty
whether the faulting was wholly subsequent to, or in part con-

1 «Causal Geology’ London, 1910, pp. 141-43 & fig. 10.
3 . Rogers & A. L. Du Toit, ‘Geology of Cape Colony ’ 2nd ed. (1969)
pp. 123-24 & fig. 9.

Vol. 67.] WoRCHSTER, ROBERTSON, AND ASHTON (Capp cotony). 731

temporaneous with the formation of the Enon Conglomerate, but it
was certainly for the most part later than the formation of this
deposit.

_ One more point still remains to be dealt with, that is to say, the
extent of the Worcester Fault. Many estimates have been given
of the maximum throw of this fault as at present existing, and it 1s
undoubtedly very great. At its most favourable development it
brings into contact Enon Conglomerate and Malmesbury Slate, but
the throw is not necessarily represented by the thickness of all the
strata which elsewhere occur between these limits. At different
points the conglomerate rests upon Ecca, Witteberg, and Bokkeveld
Beds ; and, as we have seen, there is reason to believe that before the
formation of the fault these rocks had undergone very considerable ~
folding and denudation, so that it is obviously incorrect to add
together the total thickness of the missing formations to obtain the
throw. We can only say with absolute certainty that the throw
must be at least equal to the difference of level of the upper surface
of the Malmesbury rocks on either side of the fault, and there is
unfortunately no means of measuring this directly. The lowest bed
on which Enon Conglomerate rests directly is the Bokkeveld, so the
minimum throw must be at least equal to the sum of the thicknesses
of the Table Mountain Sandstone and part of the Bokkeveld, but
this need not necessarily be much more than 5000 feet. This may
be regarded as the lower limit. On the other hand, the higher limit
is, as explained above, the total thickness of all the strata between
the Malmesbury Series and some horizon in the Ecca Series.

The thicknesses may, then, be tabulated as follows :—

Feet.

Beear sandstone?) lo:..622scecdsnsaeesn 1000
Dwyka Conglomerate ............... 2090
Witteberg Series ............ Peet. oiasa 2500
iIBolskeveld’Series 02. ..i)...0-.. cece 2500
Table Mountain Sandstone ......... 5000
Mota objerert 13,000

Tt is here assumed that the highest Ecca bed seen along the
fault is 1000 feet above the top of the Dwyka, and this, although
a very rough estimate, is probably not far from the truth.

Hence we see that the throw of the fault must be something
between 5000 and 13,000 feet, and in all probability it is nearer to
the larger figure than to the smaller. It is of course possible, and
indeed highly probable, that the throw of the fault varies, since it
has a visible length of some 70 miles and may be continued much
farther. At any rate, it may safely be said that in the middle of
its length, near Robertson, the throw is probably something like
10,000 feet, and perhaps more, a figure which is certainly large
enough to justify its inclusion among the greatest dislocations at
present known to geological science.

Qs. Gos. No. 268. 3D

732 MR. R, He RASTALL ON THE GEOLOGY OF [Nov. 1911,

In conclusion, I have much pleasure in expressing my indebted-
ness to those gentlemen whose kind co-operation did so much
to render this work possible: to Dr. Melle, of Robertson, and
Mr. J. O'Connor, of Ashton, I owe a debt of gratitude for hospi-
tality and help in the field; but above all, my thanks are due to
Dr. A. W. Rogers, on whose suggestion the work was undertaken,
and without whose help and encouragement it could not have been
carried out. ‘To these and other friends who have aided me by
advice and criticism, I tender my most hearty thanks.

EXPLANATION OF PLATE LI.

Geological map of the neighbourhood of Worcester (Cape Colony), on the
scale of 1°8 miles to the inch, or about 1 : 115,000.

Discussion.

Mr. G. W. Lampxives said that, for him, the chief interest of the
paper lay in the statements regarding the relation of the Enon
Conglomerate to the Worcester Fault. He paid a flying visit
to the Worcester district six years ago under the guidance of his
friend Dr. A. W. Rogers, and he then gathered, without, however,
himself seeing the evidence, that the Enon Conglomerate was
known to rest directly upon the Malmesbury rocks north of the
fault and to contain pebbles from these rocks. This implied that
the fault was believed in the main to be pre-Enon, though it was
recognized that there were minor movements along it at a later date.
Important conclusions as to the geological history of South Africa
generally had been based on this supposed relationship, which
was now challenged. If the Author was able to prove that
the previous investigators were wrong in their observations, he
had done good work in South Africa; but, unless his evidence was
perfectly clear, he must be prepared for sharp criticism, as the
matter was of far-reaching consequence.

Dr. J. W. Evans thought that the Worcester-Swellendam Fault
might be an ‘isostatic’ fault, determined by the gradual rise of the
high ground on the north-east and depression of the sea-floor on
the south-west, as the former was worn down by subaérial agencies
and the resulting material accumulated on the latter. It often
happened that a certain amount of basement-conglomerate occurred
on the upthrow side of such a fault, and that might be the case
near Worcester, even if the movement continued after the depo-
sition of the Enon Conglomerate. With reference to the conflict
of evidence as to the occurrence of Malmesbury rocks in the
conglomerate, he suggested that, even on the supposition that the
greater portion of the conglomerate was deposited before these
rocks were laid bare, some of it might date from a later period
when they were exposed at the surface.

The AvrHor, in reply to the points raised by Mr. Lamplugh,
pointed out that post-Cretaceous faulting did not necessarily imply

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Vol. 67.] WORCESTER, ROBERTSON, AND ASHTON (CAPE COLONY). 733

that the Cretaceous rocks were deposited at a height above their
present level equal to the total throw of the fault. He had no
doubt that a large part of the movement was of earlier date, and
considered that a post-Cretaceous movement of 2000 or 3000 feet
was sufficient to account for the phenomenon. He certainly did
not believe that the Cretaceous rocks ever extended over the Karroo,
and regarded the Enon Conglomerate as a torrential deposit formed
at the foot of a mountain-escarpment, probably a fault-scarp. He
much regretted that he had had little opportunity of discussing
the matter with Dr. Rogers, and awaited with great interest the
opinion of South African geologists on the paper. In reply to
Dr. Evans, he stated that conglomerates do exist to the north of the
fault, but these are of quite different character and undoubtedly
recent. In conclusion, the Author admitted that the view put
forward by the Cape geologists offered an easier interpretation, but
he did not believe it to be correct.

£ i

Da ee

GENERAL INDEX

TO

THE QUARTERLY .JOURNAL

AND

PROCEEDINGS OF THE GEOLOGICAL SOCIETY.

Aasvogels Nest (Cape Colony), 720.

Apui, O., Bigsby Medal awarded to,
xlvii—xlviii.

Abu Roash (Egypt), Cretaceous, &e.
of, 120, 181-32.

Acrothele cf. granulata, 302 & pl.
XXVI.

Acrotreta (Linnarssonia) sagittalis,
302-303 & pl. xxvi.

(—) aff. socialis, 503 & pl. xxvi.

Acton (Suffolk), pre-Glacial imple-
ments from, iv.

Adamthwaite Road (Ravenstonedale),
Ludlow Beds of, 230-31.

AKolian weathering in Red Sea area,
248-49 & pls. xiv-xvi.

Afquipecten camaretensis, 633 & pl.xlv.

cyrenaicus, sp. nov., 644-45 &

pl. xlvi.

cf. deletus, 644.

haueri, 634 & pl. xliv.

ef. pasinii, 632 & pl. xliv.

scabrellus, 633-84.

zittel, 632-33 & pl. xlv.

Agglomerates, rare in Skomer Vole.
Series, 185.

Agnostus fallax, 291 & pl. xxv.

Agraulos (?) holocephalus, 292 &
pl. xxv.

sp., cf. A. guadrangularis, 292-
93 & pl. xxv.

Ain Sciahat (Cyrenaica), 585.

Albania (N.), geology of, xciv.

Albite-trachytes of Skomer, 190-93
figs. & chem. anals.

Alectryonia cf. plicatula, 626-27 &
pl. xliii.

ef. virleti, 627.

Algee, calcareous, as rock-builders, iv ;
(?) in Avonian limests. of Burring-
ton Combe, 345 & pl. xxviii; see also
Lithothamnion, Mitcheldeania, &e.

ALVAREZ, J. C. W., 578.

Amauropsis alveata, see Natica.

Amphiope duffi, sp. nov., 667-68 &
pl. xlvii.

— sp. (Aquitanian), 668.
Amplexograptus perexcavatus, 456 fig.
Amplexus cornu-arietis, compared w.

Endophylium burringtonense, 378.

—— (?) sp., 557 & pl. xl.

Ampullina crassatina, 639-40.

Anadara cf. turonica, 628 & pl. xliil.

Analcite in Monmouthshire monchi-
quite, 467 fig., 468, 469, 476.

Analyses, chemical, of soda-rhyolites
& felsites, 189; of soda-trachytes &
lime-bostonite, 192; of marloesites,
200; of mugearites, 202; of
olivine-basalts, 205; of saline sand,
252; of ‘gypsumized’ bed of S&S.
Gaysum I., 254; of saline encrus-
tations (Red Sea), 254; of anhy-
drite, 256; of Welshpool dyke-
rocks, &e., 448; of monchiquite
& analogous rocks, 470, 473; of
Cyrenaican soils, 613.

Andesite (?), of Brewels Kloof, 711-
12

Anprews, C, W., 1ii, 578.
Anhydrite-deposits of Red-Sea area,
256 et segg. w. anal.
Annesley (Notts), ry.-sects. near, descr.,
81-83; sect. on G. C. R. between
Kirkby-in-Ashfield and, 80.
Annual General Meeting, ix e¢ segq.

736

Antarctic Expedition, 1907-09, viii.

Anthracite worked at Lang Vley
Station, 718.

Anthracomya lanceolata, 329-30 &
pl. xxvii.

— minima, 330-31 & pl. xxvii.

—.- phillipsi, 327-29.

williamsoni, 327.

Antigua (W. I.), & other islands,
geol. of, 681-700 figs. & pl. 1
(map).

Antillean dislocation, 688 e¢ seggq.
figs. & pl. 1 (map).

Anvil Bay (Pembroke), Upper Llan-
dovery, &c. of, 180; vert. sect.,
181.

Apollo, Fountain of, see Ain Sciahat.

Apollonia, see Mersa Susa.

Apollonia Limestones, 584 ez seqgq.,
598 et segg., 600.

Aquitanian mollusca fr. Cyrenaica,
628-36 & pls. xliv-xlv; see also
Cyrenaica, Kainozoic, gc.

ee road (Hgypt), Cretaceous of,
29.

Arser, E. A. N., [on plant-remains
fr. Culm of Exeter district], 398.

Archzan of N. Nigeria, xcviil.

Archeopteryx, gliding flight of, xeviii.

Archimylacris (Ktoblattina) hastata,
sp. nov., 160-63 & pl. ix.

(—-) woodwardi, 151.

— (Schizoblatta) obovata, sp. nov.,
157-60 & pl. vii.

spp. indet., 152-53 & pl. vu,
163-65 & pl. x.

Ardmucknish (Argyll), camptonite
compared w. Monmouthshire mon-
chiquite, 474.

Arenig age of Skomer & Trefgarn
vole. series, 182-83.

Arionellus, see Agraulos.

Arkose, assoc. w. Skomer Vole. Series,
208.

Ashdown Sands, see Wealden.

Ashgillian (?) of N.E. Montgomery-
shire, 419 e¢ segq.

Ashlake Road, see Exeter.

Ashton (Somerset), sect. near, descr.,
5d.

Ashton district (Cape Colony), geol.
of, 721-25 figs.

Ashton Great Vein (Lr. Coal-
Measures), sect. to Bedminster
Great Vein, descr. & fig. 317-20.

Assets (Geol. Soc.), statement of,

1

xl.

Athyris (Cliothyris) globularis, 564-
65 & pl. xli.

— (—) roissyi, p. 564 & pl. xh.

Auditors elected, vi.

GENERAL INDEX.

4

| Nov. nome

Augite in Monmouthshire monchi-
quite, 464-65 & pl. xxxvii, 466, 467,
fig., 472-73, 476.

Auvergnose (Skomer basalt), 205.

Ayonian of Burrington Combe, 342-
92 figs. & pls. xxvili—-xxxi; of Gower,
477-57] figs. & pls. xxxviii-xli; de-
limitation of Upper fr. Lr. in S.W.
Province, 542-48 ; see also Carbon-
iferous.

Bagley (Somerset), sect. near, descr.,
d3

Baharia (Egypt), Cretaceous of, 120;
see also El Bahr.

Bairdia cf. anpla (?), 825 & pl. xxvii.
Bala (Merioneth), Ordovic. compared
w. that of Welshpool area, 446.

Balance-sheet, xxxvi—XxxVil.

Bantry Bay(Cork), Strongylocentrotus-
bored slate, iv.

Banwell outlier (Somerset), 72.

Barbados (W.1I.), Kainozoie,
deposits of, 692-94 fig.

Barca (Oyrenaica), location of, 589.

Barpin, L. J., v.

Barks, H. F., 342, 557.

Barley House, see Exeter.

Bartow-Jameson Fund, award to J.
F. N. Green, li; list of recipients
of B:-J. Fund, xxxiii.

Bartestree (Hereford), basic intrusion
compared w. Monmouthshire mon-
chiquite, 474-75.

Basalts (olivine-bearing), of Skomer,
203-205 figs. & chem. anals.

Bastite (?), in Monmouthshire mon-
chiquite, 472.

Batuer, F. A., 345, 661; [exhibits
echinoid-radioles, &e.|, iv ; Lyell
Medal awarded to, xliv—xlv.

Bathymetrical cycles in Avonian of
Gower, 541.

Beaconsfield (Bucks), curious flint
from, xciv.

Bedminster (Bristol), sect. in South
Liberty Colliery descr. & fig., 317-
20; foss. fr. do., 325 e¢ segg.

Belan (Montgomery), Llandovery foss.
from, 484-35; Wenlock Beds at,
436.

Belemnites oweni, iv.

Bellerophon (Protowarthia) portlocki,
sp. nov., 453-54 & pl. xxxvi.

Benghazi (Cyrenaica), traverse to
Merj, 591-93; sect. to Derna,
pl. xlii; post-Plioc. mollusca fr.
beach-deposits of, 620-22 & pl. xlin;
forams., &c. in rocks EH. of, 658.

Beni Suef (Egypt), Mogattam Beds
near, 136, 137-88.

&e.

Vol. 67. |

Benyert, F. J., [exhibits pre-Glacial
implements, &c.], iv.

Berryhill (Mansfield), sect. in Trias
at, 92.

Bibliography of Permian & Trias,
114-16; of Skomer, 178-79; of

- Culm fossils, &e., 394-95; of Lr.
Palzoz. of N.E. Montgomeryshire,
415-18; of Cyrenaica, 572-77, 616—
81; of certain districts of Cape
Colony, 702.

Bigratah (Cyrenaica), 588.

Bicspy Medal, awarded to O. Abel,
xlvii—xlviii; B. medallists, list of,
XxX1li.

Billingsella cobboldi, sp. nov., 305 &
pl. xxvi.

lindstremi, var. salopiensis nov.,
303-304 & pl. xxvi; var. innom.,
304-305 & pl. xxvi.

Biotite in Monmouthshire monchi-
quite, 465, 466, 467.

Biro, C., obituary of, lix.

Bishopston (Gower), Avonian fauna
contrasted w. that of Oystermouth,
551; horizon of D,—D, Beds at,

Bissex-Hill Marls (Barbados), 692-
93

‘Black Lias’ in Avonian of Gower,
491 et seqgq.

Buakg, W. P., obituary of, lvii.

Bleadon, see Uphill.

Blue Anchor Point (Somerset), Rhe-
tic, &e. of, 11 et segg.; sect. deser.,
15-20 & pls. inv.

Bluecaster (Cautley district), Wenlock
Beds of, 217-22, w. lists of grapto-
lites.

‘Boiler-plate slabs’ (char. of igneous
rocks in glaciated districts), 717.
Bokkeveld Series (=Lr. Devonian),
702. 715 et segg.; thickness of,

751.

Bollia lata, 4538.

Botron, H., on a Collection of Insect-
Remains from the South Wales
Coalfield, 149-74 & pls. Vii-x;
Faunal Horizons in the Bristol
Coalfield, 316-41 fig. & pl. xxvii
(foss. ).

Bone Bed (Rhetiz) of Blue Anchor,
&e., 10, 11 e¢ segg.

Bonhay Road (Exeter), list of Culm
foss. from, 397.

Bonmansur, see Derna.

Bonney, T. G. [communicates A. R.
Horwood’s paper], il.

Borings (deep), evidence from as to
relats. of Permian & Trias, 100-101,
102-105.

GENERAL INDEX,

737

Bos (Pleistocene), iii.

Bostonite of Welshpool Dyke, 447-48
fic. & chem. anals.; of Abercastle,
Skomer keratophyres contrasted
with, 194.

Boswortu, T. O., the Keuper Marls
around Charnwood Forest [title
only |, Vv.

Bouttoy, W. S., on a Monchiquite
Intrusion in the Old Red Sandstone
of Monmouthshire, 460-76 figs. &
pl. xxxvli (microscop. sects.).

Bovey Tracey (Devon), plants fr.
lignite of, exhibited, iv.

Brachiopoda fr. Paradoxides Beds of
Comley, 300-306, 309-10 & pl. xxvi
(pars); range of, in Mid-Avonian
of S.W. Province, 368; see also
Billingsella, &e.

Brand Vley (Cape Colony), 703, 718.

Breach-Hill outlier (Somerset), 71.

Brecciated beds in Magnesian Limest.
of N. Durham, 312 e segqg.; br.
limests. of Burrington Combe, 345
et seqg. & pl. xxviii; see also Pseudo-
breccias.

Breede R. (Cape Colony), 703 é¢ seqq.,
(as

Brewels Kloof (Cape Colony), igneous
rocks of, 711-12.

Bristol, Avonian succession correl. w.
that of Rush & Gower, 552; Br.
coalfield, faunal horizons in, 316—
41 fig. & pl. xxvii (foss.).

Britain, paleogeography of, Ixxix—

Ixxx.

Broacer, W. C., Wollaston Medal
awarded to, xli-xhi.

Bron-y-Buckley Fault (Welshpool
district), 423 et segg., 442-43.

Broomhill Path (N. Malvern), v.

‘Bryozoa-Bed’ (Burrington Combe),
302.

Bugrat, see Bigratah.

Bunter, in relat. to Permian in Notts,
75-117 figs. & pl. v (geol. map).

Burrington Combe (Somerset), Avo-
nian of, 342-92 figs. & pls. xxvili—
5.5.

Buss, R. E. J., 173.

Butcombe - Nempnet outlier (Somer-
set), 71.

Butleigh (Somerset), sects. near, deser.,
38-39, 39-40.

Buttington Group(=Tarannon Shales)
in N.E. Montgomeryshire, 419 e
segg., 436 & pl. xxxiv.

Cenozoic, see Kainozoic.
Calcareous Grits (Hocene-Oligocene),
of Egypt, 142-43, 146.

738 GENERAL INDEX.

Calcisphera (?) in Avonian of Gower,
A487 et seqgq.

Callavia-Protolenus fauna, 297.

Callianassa-logotheti Zone, 134 et segq.

Cambrian of Comley, trilobites & bra-
chiopoda from, 282-311 fig. &
pls. xxili-xxvi.

Camel-Hill Quarry (Somerset), sect.
deser., 46-47, 48-49.

Campanian in Egypt, 119 ez segq.

Campeche (Mexico), worked flints
from, xcvill.

Caninia cornucopie, 373, 556 & pl. xl.

aff. cornucopie, mut. D,-D,, 555-

56 & pl. xl.

ainda 376-77 & pl. xxx;
differentiated into three spp., 545.

— patula, 374-76 fig. & pl. xxx.

(?) sp., 556-57 & pl. xl.

Caninia Oolite in Gower, 482-83, 497,
501, 502.

Caninia Zone at Burrington Combe,
366-69 ; physiogr. comparison w.
other areas, 387-88. ;

Canonteign (Devon), list of Culm foss.
from, 396.

CanrritL, T. C., 541; [on Skomer
Series, &c. in Pembrokeshire], 182.

Cape Systeinin Robertson district, &c.,
714 et segg., 718-19, 725 et seqg.

Caradoc (Shropshire), Ordovic. ep.
w. that of Welshpool area, 444-45.

Caradocian of N.E,. Montgomeryshire,
419 et segq.

Carbonicola acuta, 327.

aquilina, 327.

sp., 327.

Carvoniferous cephalopoda fr. Exeter
district, 399-413; success. in Gower,
477-571 figs. & pls. xxxviii-xli ; see
also Carboniferous Limestone, Coal
Measures, Culm, &c.

Carbonilerous Limestone Series of
Burrington Combe, 342-92 figs. &
pls. xxvlli-xxx1l.

Carcinophyllum 0, 317 & pl. xxxi.

Cardita sp. (Priabonian), 649.

Cardiwm-cloacinum Bed, 6, 10, 16 é&
SIME

- tuberculatum, 625.

Caribean region, phys. history of,
681-700 figs. & pl. 1 (map).

Carinaropsis acuta, 454 & pl. xxxvi.

Carisbrooke (I. of Wight), imple-
ment (?) from, ¢.

Cary Bridge (Somerset), sect. In ry.-
cuttg. deser., 43-45.

Caswell Bay (Gower), sect. descr., 486.

Catalogue of (Geol. Soc.) Library, xll.

Catcott (Somerset), Rheetic, &c., near,
37.

[Nov. 1911,

Cautley (Yorks), & Ravenstonedale,
Salopian rocks of, 215-87 figs. &
pl. xu (geol. map).

Cayevux, L., 541.

Cederbergen Folds, 730.

Cefn Group (=Upper Llandovery
pars), in N.E. Montgomeryshire,
419 et segg., 435 w. list of foss.

Cenomanian in Egypt, 119 e¢ seqq.

Cepheoued Bed (Egypt. Cretac.),

127.

Cephalopoda, Carboniferous, fr.neigh-
bourhood of Exeter, 399-413; see
also Glyphioceras, &e.

Cerastoderma edule, 621, 623-24 &
pl. xliii.

Cerithium ef. vulgatum, 620.

Ceunant Mill (Montgomery), Ordovic.
of, 424 et segq.

Chalk of England, distribut. of Pty-
chodus teeth in, 263-77 & pls. xvii-
Xxil; see also Cretaceous.

Chalky Mount (Barbados), diagram-
matic sect. at, 694.

Cuapman, F>, 578; Foraminifera,

Ostracoda, & Parasitic Fungi from

the Kainozoic Limestones of Cyren-

aica, 654-61 fig.

Charlton-Mackrell (Somerset), sect. in
ry.-cuttg. deser., 40-43.

Charnwood Forest (Leicestershire),
Keuper Marls around, v.

Chelyconus mediterraneus, 621.

Cherry-tree Bank (Montgomery), Lr.
Llandovery of, 432 ; list of foss. fr.
do., 434-35.

Cherts, radiolarian in Fostdonomya
Zone of Gow er, 495.

Cherty limestones of Burrington
Combe, 344, 346 & pl. xxviii, 361—
62; in Cyrenaica, 580-81 et segq.,
589, 590 et seqg.; see also Gower.

Chileompton (Somerset), sect. in ry.-
cuttg. descr., 66-67.

‘China-stone’ limests. of Burrington
Combe, 344 e¢ segq,

Chlamys valoniensis, maximum of,

>

Chonetes cf. buchiana, 381.

cf. comoides, two distinct forms

of, 382-83.

cf. crassistria, 582.

ct. hardrensis, 382.

— ef. laguessiana, 382.

sp., 561 & pl. xli.

Christendown Olump, see Doddis-
combsleigh.

Chrome-diopside in Monmouthshire
moncehiquite, 464-65 & pl. xxxvii.
Chromite in Monmouthshire monchi-

quite, 466, 473.

a

Vol. 67.]

Clacton-on-Sea ( Hssex), palaeolithie (?)
spearhead from, xcix.

CuarkE, W. G., [exhibits chipped
flints fr. base of Norwich Crag],
iv.

Clays, red, assoc. w. Skomer Vole.

_ Series, 207-208.

Cleeve Bay (Somerset), view of, 13.

Cleistopora Zone at Burrington Combe,
351-52, 363; physiograph. com-
parison w. other areas, 385-86;
Cl. Z. in Gower, litholog. chars.,
&e. of, 481, 496-97, 500; faunal
lists fr. do., 544.

Climatic variations in Oyrenaica, evi-
dence furnished by the wadis, 608—
12.

Clisiophyllid (early), fr. Burrington
Combe, 380-81 & pl. xxxi.

Cloddiau Group (= Upper Llandovery
pars), in N.E. Montgomeryshire.
419 et seqg., 4338-85 w. list of
foss.

Clydach Merthyr Colliery (Glamor-
gan), Hemimylacris, &e. from, 156-
57 & pl. vii, 167-70 & pl. x.

Clypeaster biarritzensis, var. trottert
nov., 662-64 & pl. xlvii; also varr.
lorioli, oppenheimi, & typica, 663.

Clyst Hydon (Devon), list of Culm
foss. from, 398.

Coal Measures of S. Wales, insect-
remains from, 149-74 & pls. vii-x ;
of Bristol district, faunal horizons
in, 316-41 fig. & pl. xxvii (foss.).

Coalpit-Heath Colliery (Glos.), foss.
found in, 821, 325 et segq.

Cospoutp, E. S., Murchison Fund
awarded to, xlix-i; Trilobites from
the Paradoxides Beds of Comley
(Shropshire), 282-300 fig. & pis.
xXxili-xxvi, 306-10, 311.

Codden- Hill Beds, & Culm of Devon,

413-14.

Celacanthus cf. elegans, 336.

Coleford (Radstock), see
Colliery.

Couns, F. G., Notes on the Culm of
South Devon: Part I— Exeter
District, 393-98, 399, 413, 414 &
pl. xxxii (map).

Colonsay (Hebrides), nepheline -
ouachitite compared w. Monmouth-
shire monchiquite, 474.

Colour - photography, new processes
of, ¢.

Colts Hill (Gower), sects. deser., 490,
491; horizon of D,-D, Beds at,
551.

Columbella rustica, 620.

Combwich (Somerset), 20.

Newbury

GENERAL INDEX. 739

Comley (Shropshire), trilobites &
brachiopoda fr. Paradowides Beds
of, 282-811 fig. & pls. xxili—xxvi.

Conocoryphe emarginata, var. longi-
frons noy., 286-87 & pl. xxiv.

Conulus subrotundus, iv.

Cooxn, Tu., obituary of, liv—lv.

Coprolites (of Coal-Measure fishes ?),
336.

Corals, ranges of, in Mid Avonian of
S.W. Province, 368; comparison
of Upper Paleozoic corals w. Lr.
Paleoz. graptolites in regard to
occurrence, distribution & evolu-
tion, 389-90; see also Caninia,
&e.

Corax pristodontus, 698.

Corbis lamellosa, 648 & pl. xlv.

Correlation of the Cyrenaican rocks,
593, 598-603 w. table; Correl.-
tables, Rhetic of Lavernock & W.
Somerset, 10; Permian & Trias in
S. Notts, S. Yorks, & Durham, 112;
of Salopian rocks in Cautley area,
&e., 232-33, 234; betw. Avonian
of Burrington Combe & thai of
other districts, 386; betw. Ordo-
vician & Silurian of N.E. Mont-
gomeryshire & those rocks in other
areas, table facing 446; see also
Gower.

Cossington (Somerset), sect. in ry.-
cuttg. descr., 36-38.

Cotham Beds (Upper Rhetic), 7-8,
9, 10 et segg.; ‘ Cotham- Marble’
structure in Avonian limests. of
Burrington Combe, 344—45,

CorswortH, M. B. [exhibits photogr.
of glacier-recession |, ii.

Corrie, J. W., 322.

Council, annual report of, ix—xi;
(& Officers), election of, xxiii.

Craters, remnants of, in Antigua,
690.

Crepner, H., [presents geol. map of
Saxony]. vil.

Cretaceous of N. Nigeria, xeviii; Cret.
& Hoc. Periods, effects in Egypt of
secular oscillation during, 118-48
& pl. vi (geol. map); Cret. of
Jamaica, &e., 700; see also Chalk,
Enon, &e.

Crick, G. C., [exhibits specims. for
T. Plowman], iv; Notes on Car-
boniferous Cephalopoda from the
Neighbourhood of Exeter, 399-
413.

Crinoidal limestones of Burrington
Combe, 348 e¢ segg. & pls. xxviii—
RX1x, 3D.

Ctenobolina cf. ciliata, 452 & pl. xxxvi

740

Cuuus, C. G., [exhibits microscope-
sects.|, v; elected Auditor, vi;
Lyell Fund awarded to, 1.

Culm of Exeter district, 393-413 &
pl. xxxii (map); Culm radiolarian
cherts regarded as a ‘ lagoon-phase,’
522-24,

Cumberland & Westmorland, relat.
of Permian & Trias in, 103-105.
Cwm Caethro (Montgomery), Wen-

lock Shales of, 436-37 map.

* Cyathaxonia’ sp., 558-59.

Cyathophyllum (2) 0, 879.

murchisont, 379-80 & pl. xxxi.

@, small mut., 546.

Cycles, bathymetrical, in Avonian of
Gower, 541; cycles of earth-move-
ment & deposition, lxy—lxvi, lxvii—
lxxil; examples of do., lxxili—lxxv ;
recurrence of type in do., Ixxxili—
lxxxiv; variability & non-recurrence
in do., Ixxxiv—lxxxvii.

Cyclonema donaldi, sp. nov., 453 &
pl. xxxvi.

Cyrenaica, contribs. to geol. of, 572-
680 figs. & pls. xlii—xlix.

Cyrena semistriuta, range of, 688.

Cyrene district (Cyrenaica), traverse
fr. Derna to, 580-83 w. sect.; do.
fr. Slonta through, 583-86 w. sect. ;
forams., &c. in limest. from, 656 ;
Cyrene Limestones, 583 ef segq.,
593 et segq., 600.

Cyrtograptus lundgrent, zone of, in
Cautley district, 219 e segg.

murchisoni, zone of, in Cautley
district, 218 et seqq.

—- rigidus, 234-35 figs.; zone of,
in Cautley district, 219 et segq.

Cyrtolites parvus, var. carinatus nov.,
455 & pl. xxxvi.

Cythere striatopunctata, 661.

— (?) wetherelli, 661.

Daxyns, J. R., obituary of, lix—lx.

Dale Gill (Ravenstonedale), Ludlow
Beds of, 230.

Datrton, L. V., [exhibits worked flints
fr. Campeche], xeviii.

Danian in Egypt, 119 e¢ segg., 129 e¢
segg., 144; its extension in HE.
Egypt, 124-29.

Dante_-Pipgton Fund awarded to
T. C. Nicholas, xev; list of re-
cipients of, xxxill.

Dassies Hoek (Cape Colony), 716.

Davip, T. W. E., [on geol. results of
Brit. Antarctic Hxpedn. |, viii.

Davidis fauna, 296-97: see also
Paradoxides Beds.

GENERAL INDEX.

»

[ Nov: aor

Daviesiella (Gower Avonian), 561.

Dawson, C., 278; [exhibits specims. ],
XCVi ; [on Wealden mammalia |,
280.

De Hoop Farm (Cape Colony), sect.
through S. part of, 721.

De Wet Station (Cape Colony), 707,
708.

Dedolomitization in Magn. Limest.
of N. Durham, 312 et seqq

Desxey, R. M., [exhibits illustrats. of
structure of glacier-ice, &c.], v-

Deltaic period in cycle of deposition,
Ixvii-lxviii.

Deposition, cycles of, lxv—lxvi, lxvii-
Ixxii; examples of do., Ixxii-lxxv ;
recurrence of type in do., Ixxxili-
Ixxxiv ; variability & non-recurrence
in do., Ixxxiy—lxxxvil.

Derna (Cyrenaica), geol. of neigh-
bourhood, 578-80 w. sect. ; traverse
fr. Cyrene to, 580-83 w. sect. ; sect.
to Benghazi, pl. xlii; foraminifera,
&e. in rocks fr. district, 654-55 ;
Derna Limestones, 579 et segg., 593
et segg,, 600.

Devonian succession in Cape Colony,
702; sce also Old Red Sandstone.
Dewey, H., 541; [on Culm of Devon,

&¢e.], 413-14.

Dewlish (Dorset), eoliths exhibited,
lv.

Dew Stones (White Lias), 37;
Sun Bed.

Distey, G. E., [exhibits specims. of
Conulus subrotundus), iv; on the
Veeth of Ptychodus & their Distri-
bution in the English Chalk, 263—
76 & pls. xvii-xxii, 277.

Dibunophyllum 6 & D. aff. W, 557-58
& pl. xl.

Dibunophylium Gone at Burrington
Combe, 344, 370-71; in Gower,
litholog. chars. of, 489-94 fig., 498-
99 & pls. xxxvili-xxxix, 504; faunal
lists tr. do., 548-52.

Dicranograpius Shales, equivalents in
N.E. Montgomeryshire, 419 eé
seqq-

Didymograptus extensus, vole. activity
in zone of, 182.

Dimorphoceras (2 discrepans), 399-
400.

Dionide sp. (?), (Trilobite - Dingle
Shales), 450-51 & pl. xxxvi.

Diphyphyllid (Seninula Zone), 547.

Diphyphyllumsp.(BurringtonCombe),
380 & pl. xxxi.

Diplograptus, see Anplexograptus.

Dipriodon valdensis, sp. nov., 278-80
fig., 281.

see also

Vol. 67.]

Dixon, E. E. L., 367; [exhibits drei-
kanter, &c.), v; (& A. Vaughan),
the Carboniferous Succession in
Gower (Glamorganshire), with Notes
on its Fauna & Conditions of De-
position, 477-567 figs. & pls. xxxviii-—
xli, 570-71.

Doddiscombsleigh (Devon), lists of
Culm foss. from near, 397.

Dolerites (olivine-bearing), of Skomer,
205-207 figs.

Douiman, P., 273.

Doiomite crystals in Red-Sea marls,
245, 261, 262.

Dolomitic sandstone in Magnesian
Limestone of S. Notts, 87 et seqgq.
figs. ; dolomitic limest. of Robertson
district (Cape Colony), 716; in
Avonian of Gower, 481 e¢ segq.

Dolomitized limestones of Burrington
Combe, 344, 348 et segg. & pls.
XXVili-xxix, 388.

Donors to Library, list of, xiii-xix.

Dorypyge lakei, sp. nov., 287-91 fig.
& pl. xxv.

Down Lane, see Doddiscombsleigh.

Dreikanter fr. Staffs., v; sand conte.
do., fr. Red-Sea area, 246 fig., 248 ;
use of term, 261.

Durr, M. B., 577, 578.

Dunball (Somerset), sect. in ry.-cuttg.
deser., 32-36.

Dundon-Hill outlier (Somerset), 39.

aie type of Egyptian Cretaceous,

30.

Dunkerton Colliery (Somerset), sect.
in ry.-cuttg. deser., 67 ; Coal Mea-
sures at, 324.

Durham Co., relat. of Permian to
Trias in, 99-101, 112; stratigraphy
& tectonics of Perm. of N. area,
312-15.

Dwyka Series (= Permo-Carbonifer-
ous pars), 702, 714 et segg.; thick-
ness of, 731.

Dyke at Welshpool, 446-48 fig. w.
chem. anals. & pl. xxxv.

Earth-movement, cycle of, lxv ; e.-m.
& ‘infilling, Ixxx—lxxxiil; other
effects of e.-m., lxxxvii-xc ; e.-m. &
life, xe—xcii ; e.-m. accompanying la-
goon-condits., 528-380, 536-37, 540-
41.

East Bridgeford (Notts), iv.

Easton Colliery (Glos.), foss. found in,
320, 327 et seg.

Ecca Shale, &c. (= Permo- Carbon-
iferous pars), 702, 705 et segg., 714
et segg., 718; thickness of, 731.

GENERAL INDEX. T4L

Eecyliomphalus contiguus, var. cam-
brensis nov., 454 & pl. xxxvi.

Kchinoidea (Triassic), radioles of, iv ;
(Tertiary) of Cyrenaica, 660-79 fig.
& pls. xlvii-xlix ; list of do., 596 ;
see also Amphiope, &e.

Echinoid Limestone (= Upper Mo-
kattam pars) of Cyrenaica, 588 ef
segg., 600.

Echinolampas chericherensis, 669-71 &
pls. xlviii—xlix.

discus, 671.

Ecker Secker Beck (Cautley district),
Wenlock Beds in, 221.

Epmr, M. D., 577.

Edington (Somerset), Rhetic,
near, 37.

Ecrrton, Rev. W. H., obituary of,
lii-ii.

Kgypt, Geol. Surv. inaps presented, ii;
effects of secular oscillation in,
during Cret. & Koc. Periods, 118-
48 & pl. vi (geol. map); observats.
on E. Desert of, 238-62 figs. & pls.
xilli-xvi; Kainozvic sequence cp.
w. that of Cyrenaica, 593, 598-
603.

El Bahr region (Egypt), Mogattam
Beds, &ce. in, 142-43.

Election of Auditors, vi; of Council
& Officers, xxiii; of Fellows, i, ui,

&e.,

ill, V, ‘Vil, ‘Vill; XClv, =xcvip Cxcixe
e-Cl.
Emborough (Somerset), sect. at

fullers’-earth works descr., 68.

Endophyllum burringtonense, sp. nov.,
377-79 & pl. xxx.

priscum, compared with £.
burringtonense, 378-79.

England (N.E)., map of Permian &
Trias of, pl. v; see also Britain.
Enon Conglomerate (=Lr. Cre-
taceous), 702, 705 et seqg., 714 et
segg., 719-21 w. sect., 722 et seqq.,

727 et segg., 731 et segq.

Eocene Period (& Cretac.), effects in
Egypt of secular oscillations
during, 118-48 & pl. vi(geol. map) ;
Eoc. age of Antigua Format., 686 ;
see also Kainozoic, Lutetian, gc.

Eoliths exhibited, iv.

Esna (Egypt), Danian, &c. S. of,
126-28.

Estheria tenella & ef. tenella, 324-25
& pl. xxvii.

sp., 325.

Estimates for 1911, xxxiv-xxxv.

Estuarine period (in cycle of de-
position), lxxi-lxxil.

Etoblattina johnsoni, 150.

742 GENERAL INDEX.

Etoblattina (Blattidium) mantidioides,
150.

—— peachii, 150.

Euspatangus sp. (Operculina Lime-
stone), 677.

Huspira cf. possagnensis, 638-39 &
pl. xlvi.

Evans, O. H., [exhibits models, &e. to
illustrate flight of Archeopteryx],
xevill.

Evolution, geographical, geology as,
]xii-xcili.

Exeter district (Devon), Culm of,
393-414 & pl. xxxii (map).

Eyron, see Port Eynon.

Fairlight cliffs, see Hastings.

Fairy Glen, see Hex-R. Mts.

Fauconer, J. D., [on the Geology of
Northern Nigeria], xcviii.

Far Gill, see Bluecaster.

Farrington Series (Coal Measures),
323 et segq.

Farrvera, G., 578.

Fault-scarps in Cyrenaica, 583, 589;
see also Tectonic.

Frarnsipzs, G. W., [exhibits Swedish
rock-specims. |, iv; [on Ordovic., &e.
of Welshpool area], 458.

Fellows elected, i, 11, ili, v, vl, vill,
XC1Y, XCV1, XCIX, C-Cl; names read
out, c, ci; number of, ix, xx.

Felsites (& soda-rhyolites) of Skomer,
185-90 figs. & chem. anals.

Hibularia Limestone (=Upper
Mokattam pars), 599, 600.

Fibularia luciant, 664-65.

Financial Report, xxxiv—xl.

Fisuer, A., 317.

Fissure-eruptions (Skomer Series),
183.

Fivehead Quarry (Somerset), Rheetie,
&e. in, 51, 52 fig.

Friert, J. S., 476; [on Skomer Vole.
Series {j, 212-13.

Fletton (Nerthants), iv.

Flexible limestone in
Limest. Series, 312.

Flint, accidental chipping of, iv:
‘head of man’ in, xciv; see also
Koliths, Implements, ge.

Flow-structure in Skomer
rhyolite, 186 fig.

Folding, dominant lines of in S.W.
Cape Colony, 725-27 w. map, 729-
30; see also Tectonic.

Fonrana, R. A., 578.

Foraminifera (ostracoda, &c.), fr.
Kainozoic limests. of Oyrenaica,
654-61 fig.; lists of same, 594-95 ;
see also Lepidocyclina, &e.

Magnesian

soda-

[Nov. 1911,

Foraminiferal sand fr. 8S. Gaysum L.,,
247 fig.; foram. limests. of Bur-
rington Combe, 344, 347 et seqq.
& pl. xxviii, 353.

Foreign Members, list of, xxiv; For.
Corresp., list of, xxv. )

Forrest, W. R., 682.

Fouquea cambrensis, 151.

Fourtav, R., 122.

Fox-Srraneways, C. E., obituary of, -

lv-lvi.

Foxcote (Somerset), Rhetic, &c. at,

67; Foxcote (& Lr. Writhlington)
Collieries, Coal Measures in, 323-
24; foss. fr. do., 329 et seg. —

Francis, J., [exhibits Jurassic
specims. |, iv.

Fron-y-fele (Montgomery), list of
Ordovie. foss. from, 429.

Fungi, parasitic, see Paleachlya.

Gaerfawr Group (=Caradocian pars),
in N.E. Montgomeryshire, 419 e¢
segg., 425-28, 429 w. list of foss. &
pl. xxxv.

Gais Gill (Ravenstonedale), Ludlow
Beds of, 230-31.

Garwoop, EH. J., [exhibits specims. of
calcareous algee|,
Secretary, xxiil; [receives Murchi-
son Medal for R. H. Tiddeman],
xliii; on the Lower Carboniferous
Succession in the North-West of
England [zitle only], xcix ; [commu-
nicates R. J. L. Guppy’s paper],
681.

‘Gash-breccia,’ use of term explained,
314,

Gasr el Harib (Cyrenaica), 580; sect.
to Bint on p. 579.

Gasr el Migdum (Cyrenaica), 588.

Gasteropod-limestones in Seminula
Zone of Gower, 503; see also Mol-
lusca, &c.

Gastrioceras listeri, 334.

Gaysum Is. (Red Sea), 244 ez segq.

Genentomum subacutwm, sp. nov.,
304-36 & pl. xxvii.

Geogram (of a formation), lxxvii.

Geographical evolution, geology as,
lxii—x¢iil.

Geological Society’s Museum, trans-
ference of, vii, ]x—lxii, cii—cili; see
also Library.

Geological Survey maps presented,
lt, wil, XCVCL.

Geology as geographical evolution,
lxii-xciil.

Gerablattina (Aphthoroblattina) sul-
cuta, sp. nov., 165-67 & pl. vill.

iv; re-elected

Vol. 67.]

Gerablattina arcuata, 173 & pl. vii.
Gharib, Wadi (Cyrenaica), 588.
Girvan (Ayrshire), Ordovic. com-
pared w. that. of Welshpool area,
446.
- Gisortia Bed (Lr. Moqattam), 137 ef
seqq.
Gisortia gigantea, 640-41 & pl. xlvi.
Glacier-ice, illustrats. of structure of,

v.

Gladys Colliery (Glamorgan), Hemz-
mylacris from, 154-56 & pl. x.

Glenkiln-Hartfell equivalents in N.E.
Montgomeryshire, 419 é7¢ segg.

Glycymeris glycymeris, 621.

—— pilosa, 622-23.

Glynde (Sussex), Ptyehodus decurrens
from, xev.

Glyphioceras beyrichianum, 400-401.

crenistria, 406—407.

davisi, 403-404.

diadema (/), 334.

——— inconstans, 404-405.

—— phillipsi, 405.

retictlatum, 402-403.

sphericum, 406.

spirale, 407-408.

striolatum, 401-402.

Golden Hill (Monmouth), monchi-
quite-intrusion in O. R. S. near,
460-76 figs. & pl. xxxvii (microsp.
sects.).

Gower (Glamorgan), Carb. succession
in, 477-571 figs. & pls. xxxviii-xli.

Graigola Seam (Pennant Series), in-
sect-remains from, 151 et segq.

Grand Pacific & Muir Glaciers, re-
cession of, il.

Granite of Robertson district, 714,
716-18.

Granitic dykes, crushed,in Worcester
& Robertson districts (Cape Co-
lony), 706, 710-11, 715.

Graptolites (Lr. Palzozoic), com-
pared w. Upper Paleozoic corals in
regard to occurrence, distribution,
& evolution, 389-90 ; see also Am-
pleacgraptus, &e.

Graptolitic fauna of Wenlock Beds of
Cautley district, 222, 226; of Lud-
low Beds ibid., 229; of Salopian of
Wales, &c. correlated w. same of
Cautley area, 252-33; of Salopian
of N.E. Montgomeryshire, 441-42.

Grassholm I. (Pembroke), 175, 184.

Gravels (‘igneous’) of EH. desert of
Egypt, 238-40; sandy do. ibid.,
241.

Great House, see Golden Hill.

‘Gruen, J. F. N., Barlow-Jameson

Fund awarded to, li.

GENERAL INDEX.

743

Grecory, J. W., the Geology of
Cyrenaica, 572-615 figs. & pl. xlii
(map & sects.), 680; the Fossil
Echinoidea ot Cyrenaica, 661-78 &
pis. xlvii—xlix.

Grey Marls, see Sully Beds & Keuper.

Grist, C. J., [exhibits eoliths], iv.

Groes-pluen (Montgomery), Ordovie.
foss. from, 426.

Groomii fauna, 297, 298; see also
Paradoxides Beds.

Grubble-Hill outlier (Somerset), 72.

Guadeloupe (W. [.), diagrammat.
sect. across, 689

Gubah (Cyrenaica), 582.

Guilsfield (Montgomery), Ordovic.
near, 421 et segg,; Wenlock Shales
near, 438 w. map.

Gunna, Jebel (Sinai), sect. deser.,

Gurry, R. J. L.,on the Geology of
Antigua & other West Indian- Is-
lands with reference to the Physical
History of the Caribean Region,
681-700 figs. & pl. 1 (map).

Gwern-y-Brain (Montgomery), sects.
descr. & fig., 421-22, 428.

Gwern-y-brain Group (= Ashgillian ?),
in N.H. Montgomeryshire, 419 e¢
segg., 428-31 w. list of foss.

Gwitiiam, G. T., [drawings of echi-
noid-radioles exhibited], iv.

Gypsum, grooved by water-action, iv;
gypsum-workings (Watchet dis-
trict), 13 e¢ segg. & pl. ii; gypsum
(& salt) in Red-Sea area, 251-58 &
pl. xvi.

Hadahid, Jebel (Egypt), sect. deser.,
142.

Bear Hs C2540;

Ham-Hill inlier (Somerset), 50.

Hamema, Wadi (Cyrenaica), 590.

Hamiine, J. G., 541.

Hammama (Egypt), type of Creta-
ceous, 124,130, 144.

Hanham Colliery (Glos.), foss. found
in, 320.

Hanna R., [bequest made by], x.

Hapsford Mills (Somerset), sect.
descr., 64-65.

Harptree area (Somerset), Rheetic, &c.
of, 69-70.

Harrison, B., [exhibits eoliths, &c.],

iv.

Hartebeest R. (Cape Colony), 706,
707, 708.

Harter Fell (Cautley district), Wen-
lock Beds of, 227. :

Hasevuurst, S. R., 315.

744

Hastings (Sussex), mammalian teeth
fr. Wealden of, 278-81 figs.

Hawashian sub-type of Egyptian
Cretaceous, 130.

Haynes, P., 692.

Hayti or Haiti (W. I.), 690.

Heapny, T. M., obituary of, lvili-lix.

Heathfield (Devon), plant-remains
from, exhibited, iv.

Helicella tuberculosa, 620 & pl. xiii.

Helix labyrinthica, range of, 687-88.

Helvetian - Tortonian mollusca of
Cyrenaica, 625-28 & pl. xliil; see
also Kainozoic.

Hemiaster scille, 673.

Hemimylacris convexa, sp. nov., 156—
57 & pi. vii.

obtusa, sp. nov., 154-56 & pl. x.

Hex-R. Mts.(Cape Colony), diagramm.
sect. fr. Worcester to, 705.

Highbury Colliery, see Mackintosh
Colliery.

Hill-House Beds (Cambrian), 2838 ez
seqq., 297.

Hinp, W., 399.

Hinpz, G. J., [on Spongiostroma (?)
in Burrington limest.], 345; [on
sponge-spicules & radiolaria (?)
ibid. |, 346.

Hinton - Blewet area
Rheetic, &e. of, 69.

Holwell (Somerset),
sect. deser.. 62-64.

Homster (Cumberland), cleaved vol-
canic ash from, cl.

Hoops R. (Cape Colony), 715, 716.

Horny limestone, see Brecciated,
Cherty, ¥c.

Horwoop, A. R., the Origin of the
British Trias [7z¢le only], il.

Howarp, F. T., 212.

Hows, J. A., 399, 541; [exhibits
curious flint], xciv.

Howett, Major E, 212.

Howley-Langport area (Somerset),
Rhetic. &c. of, 51-53.

Hoyos, Count A., [on award of Bigsby
Medal to O. Abel], xlvii—xlviii.

Hugues, T. McK., [on Paleoz.
sequence in Cautley district], 236-
37.

Hume, W. F., the Effects of Secular
Oscillation in Egypt during the
Cretaceous & Hocene Periods, 118—
46 & pl. vi (geol. map), 148.

Hungary, Geol. Surv. map presented,
ci.

Hygromia sordulenta, 619 & pl. xlin.

Hypersthene- bearing trachytes of
Skomer, 190, 192-93 fig.

Hypsoclypeus hemisphericus, 671-73.

(Somerset),

Marston-Road

GENERAL INDEX.

[Nov. 1911,

Ice in glaciers, structure of, v.

Iddingsite (?) in Monmouthshire
monchiguite, 472.

Idestone Hill (Devon), Culm foss.
from, 397.

Igneous rocks of N. Nigeria, xeviii;
‘igneous’ gravels of KH. desert of
Egypt, 238-40; i. r. of Welshpool
area, 446-48 fig. w. chem. anals. ;
of Brewels Kloof, 711-12; see also
Basalt, Dolerite, fc.

Iutinewortu, 8. R., 260.

Implements, Mousterian, found in La
Cotte cavern, ili; infra-Crag, &c.,
iv; fr. Campeche, xcviii.

Infilling (stratigraphical) & earth-
movement, Ixxx—]xxxiii.

Insect-remains fr. S. Wales coalfield,
149-74 & pls. vii-x; see also Genen-
tomum, &e.

Ipswich (Suffolk), infra-Crag imple-
ments (?) from, iv.

Ishgerib, see Jeraib.

Lsodiametric lines in paleogeography,
Ixxvli.

Isostatic character of Worcester Fault
suggested, 732.

Jagonia pecten, 622 & pl. xliii.

J ra (B.W.I.), Cretaceous, &c. of,

Jebril, Wadi (Cyrenaica), 589.

Jeffry’s Haven (Pembroke), Upper
Llandovery, &c. of, 180-81 w. vert.
sect.

Jemsa, Gulf of (Red Sea), saline
mud, &c. of, 244 et segg. figs. &
pl. xiv.

Jeraib, Wadi (Cyrenaica), 587-88;
forams., &c. in limest. from, 657.
Jersey, excavations in La Cotte cavern,

Thi,

Jet, fr. Robin Hood’s Bay, iv.

Jew or Dew Stone, see Sun Bed.

Jouns, C., 388.

Jonus, O. T., 212; Wollaston Fund
awarded to, xlix.

Jones, T. R., {initiation of Memorial
Fund ], xevii.

Jonesella crepidiformis, 451, 452 fig.

obscura, 451-52 fig.

Jubal I. (Red Sea), 244 e¢ segq.

Jurassic plants fr. Marske Quarry, ii;
see also Lias, &e.

Kainozoic of Cyrenaica, 572 et segq.
figs. & pl. xlii (map & sects.) ; mol-
lusea 2b7d., 616-53 & pls. xliii—xlvi ;
foraminifera, &c. ¢bid., 654-61 fig. ;

pel. 67. |

echinoidea id., 661-79 fiz. &
pls. xlvii-xlix; K. rocks of N.
Nigeria, xeviii; of Antigua & other
W. Indian islands, 683 e¢ segq.

Ee ohoR,

Karroo System, 702, 703 e¢ seqq.,
718-19; tectonic feats. of. 725 e¢
seqq.

Keratophyres of Skomer, 193-95 figs.

Keuper Marls around Charnwood
Forest, v; Keuper in Somerset, 3
et segg., 9,10 et segg.; in S. Notts.,
79; see also Trias.

Keuperian, term suggested, 73.

Keur Kloof (Cape Colony), 715,
716.

‘ Keystone faulting’ in Welshpool area,

43.

Khumas, Wadi (Cyrenaica), 587.

Kilabia (Egypt), Danian, &c. near,
126-28.

Kilchattan, see Colonsay.

Kimberley (Notts), sects. betw. Not-
tingham and, descr., 83.

Kine, H.M. the, reply to address of
condolence, 1.

Kingswood (Bristol), foss. found in
Speedwell Deep Colliery, 320-21,
332 et seqq.

Kirkby-in-Ashfield (Notts), sect. on
G.C.R. betw. Annesley and, 80.
Klaas Voogds R. (Cape Colony), 720,

721.

Knoll phase (Avonian), see Waul-
sortian.

Kogmans R. (Cape Colony), 722;
diagramm. sect. along banks of,
723; Kogmans Kloof, 721, 728.

Krausella armata, 453.

Kriscer, J., 578.

LABASTIDE, —, 693.

Labruk (Cyrenaica), 582.

La Cotte cavern (Jersey), recent ex-
cavations in, li.

Lagoon-phases, (more especially) in
Gower, 511-31 figs.

Laxg, P., 300.

Lake District, Ordovic. compared w.
that of Welshpool area, 446.

LamBest, J., 661.

Laminosa Dolomites in Gower, 483—
84, 501.

Lamludeh (Cyrenaica), 582.

Lampuuen, G. W., [exhibits shells fr,
Spitsbergen |, iv.

Lamproptilia tenuitegminata, sp. nov.,
170-72 & pl. x.

Lancherley Cross (Somerset), Rhezetic,
&e., of, 61.

GENERAL INDEX.

Landscape- Marble structure in
Avonian limests. of Burrington
Combe, 344 e¢ seoq.

Lang, Rev. G. J., Jurassic Plants from
the Marske Quarry [title only], ii.

Lang Vley Station (Cape Colony), 718.

Lange Kloof (Cape Colony), supposed
Enon Conglowm. of, 720, 727-28.

Langport-Somerton area (Somerset),
Rhetic, &e. of, 49-50 ; Langport-
Howley area, do., 51-53 fig.

Langport Beds (Upper Rkeetic), 8, 9,
10 et seqq.

Lapwortn, C., 300, 457; [exhibits
specins. of Paradoxides groomit|,
XCVil.

Lareg, B., 273.

Lavas of Skomer Vole. Series, chem.
& mineralog. compn. of, 209-10 w.
diagram ; see also Skomer.

Lavernock (Glamorgan), table showg.
comparative sequence of deposits in
W. Somerset & at, 10.

Leaia leidyi, var. salteriana, 325-26
& pl. xxvii.

Lepidocyclina elephantina, 660.

Leptoblattina extlis, 150.

Lias of Yorks, fossils, &c. from, iv;
(Lr.) of Somerset, 4 e¢ seqq., 9.

Library (& Museum) Committee,
annual report of, xi-xiil; lists of
donors to Library, xili—xix.

Libyan Series (Lr. Eocene), in Egypt,
134-35.

Lichfield (Staffs), dreikanter fr. neigh-
bourhood of, v.

Lite, organic (& earth-movemt.), xc—
X¢cll.

Lilstock (Somerset), sect. deser., 26-80,

Lingula mytiloides, 333.

obtusiformis, sp. nov., 455 &

LSSGKy

Lingulella cf. ferruginea, 300-801 &
pl. xxvi.

-—— spp. indet., 301 & pl. xxvi.

Lithological characters of the Avonian
Zones in Gower, 480-506 figs. &
table facing p. 506; see also Dolo-
mites, fc.

Lithomylacris kirkbyi, 150.

Lithostrotion ef. irregulare, 547,

Intthothamnion in Cyrenaican rocks,
655 e¢ seqq.

Little Stoke, see Lilstock,

Llandeilo Flags in relat. to Skomer
Series, 182.

Llandovery (Upper) of Skomer, &c.,
& its relat. to Volcanic Series,
180-81 figs.; Llandovery & assoc.
rocks of N.E. Montgomeryshire,
415-59 figs. & pls. xxxiii-xxxvi.

746

Llanrhidian (Gower), fauna of Di-
bunophyllum Zone at, 499,

Llyswen (Montgomery), Llandovery
foss. from, 485.

Long Mountain (Shropshire), Silurian
compared w. that of Welshpool area,
445,

Loripes lacteus, 622.

Lower Writhlington (& Foxcote) Col-
lieries (Somerset), Coal Measures
in, 323-24; foss. fr. do., 327 et segq.

Loxoconcha cyrenaica, sp. nov., 660-

1 fig.

Loxonema sp.
354.

Lucina cf. nokbaensis, 647-48.

cf. pharaonis, 647.

Luciniform casts fr. Aquitanian of
Cyrenaica, 636.

Ludlow Beds of Cautley & Raven-
stonedale, 228-31 w. list of foss.,
234; of N.E. Montgomeryshire,
419 et seqg., 439-40 w. list of grap-
tolites (441-42).

Ludlows (& Middle) Pits (Somerset),
Coal Measures in, 323.

Lueron, M. [presents geol. map], vi.

Lutetian mollusea fr. Cyrenaica, 649—
50; see also Kocene, Kainozoie, gc.

Lyett Medals awarded to F. A.
Bather & A. W. Rowe, xliv—xlvii;
Geol. Fund, award to C. G. Cullis,
1; L. medallists, list of, xxx; reci-
pients of L. Fund, list of, xxxi.

(Lr. Coal-Measures),

Macponap, D. P., 578, 590, 601;
the Foraminiferal Limestones of
Cyrenaica [title only], xcv.

Mackintosh (& Newbury) Collieries
(Somerset), Lr. Coal-Measures of,
321-22.

Maes -y-cwmmer (Monmouthshire),
insect-remains fr. Coal-Measures
near, 152 et seqq.

Mactra cf. fourtaui, 648-49.

stultorum, 622.

Magnesian Limestone in 8S. Notts,
79 et segg.; ‘sandy’ developmts. in
do. ibid., 87 et segq., figs.; paleon-
tology of, 105-109 w. lists of foss. ;
M. L. of N. Durham, 312 é segq.

Malmesbury Series (pre-Cambrian),
702, 704 et segg., 714, 715-16, 720
et segg. ; petrography of, 708-12.

Malta, Kainozoic sequence <p. w. that
of Cyrenaica, 602, 603.

Manchester district (Lancs.), relat. of
Permian to Trias in, 105.

Manjak, &c., origin of, 699-700.

Mansfield (Notts), Permian, &c. of
district, 86 e¢ seqq. figs.

GENERAL INDEX.

[ Noy. Vora

. Manzanilla Beds (Trinidad), 696.

Maps presented, li, vi, Vii, xev, xcvii,
ci; map of Sparkford-Hill area
(Somerset), 44; geol. map of S.
Notts, 78; map of Permian & Trias
of N.E. England, pl. v; geol. map
of Skomer I. & part of adjacent
Pembrokeshire Coast, pl. xi; of
Cautley District, pl. xii; map
showg. distrib. of ‘igneous’ gravels
in Egypt, 248; geol. map of part
of Red-Sea area, 255; map
of Burrington Combe & imme-
diate neighbourhood, 348; geol.
sketch-map of Exeter district, pl.
Xxxli; map illustratg. exposures
in Cwm Caethro, 437; showg.
Wenlock zones exposed in Guils-
field Brook, 488; geol. map of
neighbourhood of Welshpool,
pl. xxxili; map of neighbourhood
of Great Ho., Golden Hill, 461;
topogr. & geol. maps of Gower, 478,
479; sketch-map illustrate. tectonic
relats. of COyrenaica, 604; geol.
map of Cyrenaica, pl. xli1; outline
map of Antigua, 683; map showg.
trend of great Antillean Disloca-
tion, pl. |; geol. map of district
round Montagu & Ashton, 722;
map showg. dominant trend-lines
of S.W. Cape Colony 726; geol.
map of neighbourhood of Worcester
(Cape Colony), pl. li.

Marble, crystalline, in Worcester dis-
trict (Cape Colony), 706, 709-10.
Marine Bands in Bristol Coal Mea-

sures, 317 et seqq., 339-40.

Marls, format. of, in Red-Sea area,
244 ef seqq.

Marl Slate (Permian) in 8S. Notts,
81 et segg.; in N. Durham, 312
et seqgq.

Marloes (Pembroke), Skomer Series,
&e. betw. St. Ishmaels and, 182.

Marloesites of Skomer, 198-201 figs.

Marr, J. E., re-elected V.P., xxiii;
[communicates paper by Miss Wat-
ney & Miss Welch], 215.

Marske (Yorks), Jurassic plants from,
il.

Marston Road (Somerset), sect. descr.,
62-64.

Martin, E. A., [exhibits various auto-
graphs], v.

Martinia glabra, 564.

Matuer, E., 260.

Maitery, C. A., Notes on some of the
Brachiopoda from the Paradoxides
Beds of Comley, 300-306, 309-10
& pl. xxvi (pars).

Vol. 67.]

Matruew, G. F., 300.

Mayar, Capt. —, 212.

Maze Kraal (Cape Colony), 707.

Megalichihys pygmeus, 336.

Melanella hemidiscus, gen. et sp. nov.,
451-52 fig.

Meuse, —, 721, 732.

Merj (Cyrenaica), traverse to Messa,
587-89; do. to Ptolemeta, 590-91 ;
do. to Benghazi, 591-93 ; foramini-
fera, &c. in rocks of district, 658 ;
sect. fr. fault-scarp to Ptolemeta,
pl. xli.

Mersa Susa (Cyrenaica), traverse to
Slonta, 583-86 w. sect.

Mesozoic rocks of N. Albania, xciv.

Messa (Cyrenaica), traverse to Slonta,
287; do. to Merj, 587-89 ; forams.,
&e. in rocks fr. district, 657.

Metamorphic rocks of N. Nigeria,
xevili; see also Marble, &c.

Michelinia konincki, nom. nov., 372 &
Die kxX.

megastoma, mut. Z,, 371.

Microdiscus sp., ef. M. punctatus, 292
& pl. xxv.

Microlesies Marls, see Sully Beds.

Microliths, see Implements.

Middle Gill, see Bluecaster.

Middle-House Dingle (Montgomery),
Ordovic. foss. from, +24.

Middle (& Ludlows) Pits (Somerset),
Coal Measures in, 323.

Midland I. (Pembroke), 175, 184,185.

Millstone Grit boulder fr. Hertford
rit. c.

Milton Lane (Somerset), sect. descr.,
57-58.

Mincing Lake (Devon), list of Culm
foss. from, 398.

Mitcheldeania-like alga in Avonian of
Gower, 498, 502.

Modiola phases in Avonian of Gower,
485-87, 188-89, 496, 498, 500, 502-
503; regarded as calcareous lagoon-
phases, 513-19 w. sect.; diff. betw.
radiolarian phase & JZ. phases, 524-
25; relats. & geogr. extent of latter,
526.

Moel-y-Garth (Montgomery), _ sect.
deser. & fig., 420-21; M.-y-G. Fault,
424 et seqq., 443.

Moela Oasis (Egypt), Moqgattam Beds
W. of, 136 ez seg.

Morr, J. R., [exhibits infra-Crag im-
plements ?|, iv.

Mollusea (Kainozvic), of Cyrenaica,
596-97, 616-53 & pls. xlii—xlvi.
Monchiquite-iatrusion in O. k.S. of
Monmouthshire, 460-76 figs. &

pl. xxxvii (microscop. sects.).

Qi. Gs. No: 265,

GENERAL INDEX.

TAT

Monograptus leintwardinensis, zone of,
in Cautley district, 228 et segq.

nilssont, zone of, in Cautley
district, 228 ez seqq.

riccartonensis, zone of, in Cautley
district, 219 e segq.
vulgaris, 456 fig.
wandalensis, sp.

235-36

nov.,

fig.

Montagu (Cape Colony), geol. map of
district round Ashton and, 722.

Montgomeryshire (N.H.), Llandovery
& assoc. rocks of, 415-59 figs. &
pls. xxxiii-xxxvi.

Mogattam Series (Middle Eocene), in
Egypt, 136-43.

Morey, F’, c.

Mousterian implements found in La
Cotte cavern, Ili.

Mugearites of Skomer, 201-203 w.
chem. anals., 197 fig.

Muir & Grand Pacific Glaciers, re-
cession of, ii.

Murcuison Medal, awarded to BR. H.
Tiddeman, xlii-xliii; Geol. Fund,
award to E. 8S. Cobbold, xlix-l;
Murchison medallists, list of, xxviii;
recipients of M. Fund, list of, xxix.

Musclewick (Pembroke), 182, 184, 186,
&e.

Museum (Geol. Soc.), transference of,
vii, lx-lxii, cii-ciil; annual report,
xiii.

Mynyddislwyn Vein (Upper Coal-
Measures), insect-remains from, 151
et seqq.

Nagr, Wadi (Cyrenaica), sect. in pla-
teau-face at, 581.

Naiadites cf. carinata, 3382 & pl. xxvii.

—— elongata, 331 & pl. xxvii.

sp., 332.

Names of Fellows read out, e, ci.

Naparima Series (Trinidad), 697-98.

Nariva Series (Trinidad), 697; limi-
tation of term, 699.

Narthwaite Quarry (Wandale Hill)
Ludlow Beds in, 229.

Natica phasianelloides, 685.

Natrolite (?) in Monmouthshire mon-
chiquite, 46%. é

Nuauz, J. J., 212.

Near Gill, see Bluecaster.

‘Negative breccia,’ see Magn. Limest.
of N. Durham.

Nels R. (Cape Colony), 716, 717.

Nempn et outliers (Somerset), 70-72.

Nepheline-ouachitite of Colonsay
compared w. Monmouthshire mon-
chiquite, 474.

OE

748 GENERAL INDEX.

Newbournian Crag, implements (?)
found below, iv.

Newbury (& Mackintosh) Collieries

_: (Somerset), Lr. Coal-Measures of,
321-22, 333 et seqq.

New Rock Series (Coal Measures),
321 et seg.

Newron, EH. T., [exhibits accidental
flint-tlakes], iv.

Newton, R. B., 578; Kainozoie Mol-
lusca from Oyrenaica. 616-53 &
pls. xlii-xlvi.

Nicnouas, T. C., Daniel-Pidgeon Fund
awarded to, xev.

Nicon.s, H. T., ii.

Nigeria (N.), geology of, xcviii.

Nodular rhyolite of Skomer, 187-89
fig.

Nomismoceras spirorbis (¢), 408.

Norcsa, Baron F., [on the geology of
N. Albania], xciv.

Norris, F. E., [exhibits seismographic
record], vil.

Norwegian Minister, sce Voar.

Norwich Crag, implements (?) found
below, iv.

Nottinghamshire, relationship of Per-
mian to Trias in, 75-117 figs. &
pl. v (geol. map).

Nubian Sandstone, relat. of fossilif.
Oretac. strata to, 119-23, 144.

Nucula oblonga, 333 & pl. xxvii.

Number of Fellows, ix, xx.

Nummulites curvispira, var. major
noy., 659.

Nummulites-gizehensis Beds in Egypt,
131, 132, 188 et segg., 145; in
Cyrenaica, 654 et seqq.

Nunney-Elm area (Somerset), Rheztic,
&e. of, 61-65.

Nuy R. (Cape Colony), 719.

Oasis type of Egyptian Cretaceous,
128, 130.

Obituaries of deceased Fellows, lii—lx.

Oceanic Beds of W. Indies, 692 e¢
seqq.

Ocellar spacesin Monmouthshire mon-
chiquite, 467 fig., 468.

O'Connor, J., 722, 725, 782.

Officers (& Council), election of, xxiii.

Oxsz, A. W., [exhibits implement (?)
fr. Carisbrooke], c.

Old Red Sandstone of Monmouth-
shire, monchiquite-intrusion in,
460-76 figs. & pl. xxxvil (microscop.
sects. ).

Olenellus Limestone (Comley), fauna
of, 297, 298.

[Nov. rot,

Olifants Klip (Cape Colony), ottrelite-
rock, 7138.

Oligocene, inapplicability of term to
W. Indian Kainozoic, 699 ; see also
Kainozoic.

Olivine in Monmouthshire monchi-
quite, 465-66, 467 fig., 472.

Olivine-basalts of Skomer, 203-205
figs. & chem. anals.; olivine-doler-
ites ibid., 205-207 figs.; olivine-
augite-rock inclusions in Mon-
mouthshire monchiquite, 471-74 &
pl. xxxvil.

Oolitic limestone (Avonian) of Bur-
rington Combe, 345 e¢ seqg. &
pl. xxviii, 352-53; see also Caninia
Oolite.

Oopecten rotundatus, 684-35 & pl.
xliv.

Operculina-lybica Zone, 134 et seqg.

Ophiolepis damesi, horizon of, 6.

Orbitoides Beds of Antigua, 688 ef
segqg.; of Trinidad, 696-98 fig.

Orbitolites complanata in Red-Sea
foraminiferal sand, 247.

Ordovician of N.E. Montgomeryshire,
422-31 figs. & list of foss.; see
also Ashgillian, Gaerfawr, gc.

Ore-deposition & earth-movemts.,
Iexauing

Orthis (Orusia) cf. lenticularis, 306 &
pl. xxvi.

(?) sp., 306 & pl. xxvi.

Orthoceras koninckianum, 409.

—- obtusum, 409-10.

spp. a & B, 410.

Orthomylacris lanceolata, sp. nov.,
167-70 & pl. x.

Orthophragmina pratti, 659-60.

‘ Orthotetes’ cf. crenistria, 561 &
pial:

Oscillation, secular, in Egypt, during
Cret. & Eoc. Periods, 118-48 &
pl. vi (geol. map).

Ostracoda in calcareous grit of Bur-
rington Combe, 352 & pl. xxix;
in Kainozoic limests. of Cyrenaica,
660-61 fig.; list of do., 596; see
also Hstheria, Ke.

Ostrea Beds (Ur. Lias), 4 e¢ segq.;
(Cretaceous of Egypt), 120, 123,
127.

Ostrea cf. caudata, 629-380 & pl. xliv.

crassicostata, 630 & pl. xlv.

edulis, 621.

—- ef. ventilabrum, 642 & pl. xlv.

sp. indet. (Lutetian), 650.

Ostrea-nulticostata Zone, 154 e seqg.

Ottrelite-schist in Worcester district
(Cape Colony), 707.

Vol. 67.]

Overthrusts in Welshpool area, 443.

Oystermouth (Glam.), view of ‘ Black
Lias’ quarry, 492; see also Gower
paper passim.

Paleachlya sp., 659.

Paleogeography, phases of, Ixxvi-
Ixxxvii.

Palzoliths exhibited, iv; palzo-
lithic (?) spearhead exhibited, xcix.
Paleoxyris helicteroides, 336 &

pl. xxvii.

Pantellerite, marloesite
with, 198 figs., 200.
Paper Shales (Lr. Lias), 9, 10 e

seqq.

Paradoxides Beds of Comley, trilo-
bites & brachiopoda from, 282-311
fig. & pls. xxiii—xxvi.

Paradoxides davidis, 285 & pl. xxiv.

groomit, 283-85 & pl. xxi.

rugulosus, 286 & pl. xxiv.

spp. indet., 285 & pl. xxiv.

Parian sub-continent, physiogr.
history of, 695-96.

Paris, H. T., 40.

Parkfield Series, see Coalpit-Heath
Colliery.

Pateshill Copse, see Perridge.

Pebble-beds in E. desert of Egypt,
238-39 ; distrib. of pebbles in same,
242-44 w. map.

Pecten arcuatus, 643-4+ & pl. xlvi.

vezzanensis, 631-32 & pl. xlv.

zizinieé, 627-28.

Pecten Bed (Lr. Rhetic), 10 e¢ segq. ;
Pecten Limestones (Cretaceous),
127.

PELLETIER, F., 278, 280.

Penbryn (Montgomery), Ordovie. of,
423 e¢ seqq.

compared

Pendleside Series, & Culm of Devon, —

411 et segg.; P. S. equivalents in

Gower, 494-96.

Penller-gaer (Glamorgan), see Gladys

‘Colliery.

Pennant Grit, arthropoda from, 338.
Pentamerus Limestone of Cefn, 435.
Perlitic structure in Skomer soda-

rhyolite, 186 fig.

Permian, relationship of, to Trias in
Notts., 75-117 figs. & pl. v (map);
Perm. deposits cp. w. recent do.
in EH. desert of Egypt, 241-42;
Perm. of N. Durham, stratigr.
& tectonics of, 312-15.

Perridge (Devon), lists of Culm foss.
from, 397.

‘Petit granit’ (=crinoid fragmental
limestone), 349 & pl. xxix.

GENERAL INDEX.

749

Petroleum, &c., origin of, 699-700.

Petroliferous radiolarian earth in
Barbados, 693.

Photography, see Colour-photography.
‘Phyllite-gneiss’ of Worcester district
(Cape Colony), 706, 710-11, 715.
Physiography of certain districts of
Cape Colony, 703-704; sce also
Earth-movements, Geographical

evolution, ge.

Picotite in Monmouthshire monchi-
quite, 466, 475.

Picrite, xenoliths of, in Monmouth-
shire monchiquite. 473-74.

Proton, T., 212.

Pipenon Fund, see Daniel-Pidgeon
Fund.

Pigeon-House outlier (Somerset),
(ae

Pinhoe (Devon), lists of Culm foss.
from, 398.

Plagiaulax dawsoni, 278, 280.

Planetismal hypothesis, vii.

Plant-remains fr. Bristol Coalfield,
326; maxked assoc. of pl.-rem. w.
blattoid wingsin 8S. Wales Coalfield,
172; pl.-rem. fr. Culm of Exeter
district, 398-99.

Pleistocene of Cyrenaica, 593; list of
mollusea fr. do., 596 (see also Post-
Pliocene) ; poss. variats. in Pleistcc,
climate of Cyrenaica, 608-12;
Pleistoc. mammalian remains in
La Cotte cavern, lii; at Clacton-
on-Sea, xcix.

Pleurophorus Bed, 2, 6, 10 et segq.

Prowman, T., iv.

Plumley’s Den, see
Combe.

Poecombe (Devon), list of Culm foss,
frow, 397.

Polden-Hills area (Somerset), Rheetie,
&e. of, 31-45.

Poruarp, W., 541.

PotwHevzt, J. R., obituary of, liii—
liv.

Polyzoa ‘n Burrington-Combe lime-
stones, 351, 352 & pl. xxix, 353.

Porz, W. J., [on new processes or
colour-photography ], c.

Popehouse Close (Devon), list of
Culm foss. from, 397.

Porphyrite (?) of Brewels Kloof, 711-
12

Burrington

Port Eynon (Gower), horizon of
D,-D, Beds at, 551-52; see also
Gower.

Posidonomya Gone in Gower, litholog.
chars. of., 494-96, 504.

PostLeruwalrte, J., [exhibits specim.
of cleaved volcanic ash], ci.

750

Post-Pliocene mollusca of Cyrenaica,
619-25 & pl. xliii; see also
Pleistocene.

Powis-Oastle Group (=Lr. LUlan-
dovery), in N.E. Montgomeryshire,
419 et seqq., 481-38 sect.

Preston, H.,[exhibitsgypsum grooved
by water-action], iv.

PreEstwicu medallists, list of, xxxii.

Priabonian of Cyrenaica, mollusca
from, 636-49 & pls. xlv—-xlvi; see
also Cyrenaica, Kainozoie, &c.

Prisstuey, R. E., viii.

Primitia tumidula, 452.

ulrichi, 452.

Primitiella unicornis, 452 & pl. xxxvi.

Prine, J., 173.

Productus aff. cora, 365.

cf. pustulosus, 545.

sulcatus, 559-60 & pl. xh.

— (Marginifera) longispinus, var.,
560 & pl. xli.

Prolecanites (2) sp., 408-409.

Protolenus-Callavia fauna, 297.

Pseudobreccias of Dibunophyllum Zone
in Gower, 489, 507-11 fig. & pls.
XXXVii1-XXxix.

Pseudoedmondia (1), sp. nov. (Somer-
set Coalfield), 332 & pl. xxvii.

Pseudomonotis Bed, 7.

Pseudomorphs after augite in Skomer
rocks, 188 figs.

Pteria-contorta Shales, 2 e¢ seqq.

Pterinopecten papyraceus, 338.

Ptolemeta (Cyrevaica), traverse to

~ Merj, 590; sect. to Merj fault-
scarp, pl. xli1.

Ptychodus, distribut. of teeth in Eng-
lish Chalk, 263-77 & pls. xvii-
Xxil.

—— decurrens, 264-65, pls. xvi &
xix; var. depressus, 266 & pl. xvii;
var. levis, 267; var. multistriatus,

267 & pls. xvili-xix; var. oweni,

266-67 & pls. xvili-xix ; geol. range

of, 267-68.

dixont, sp. nov., 270-71 & pl. xx.

latissimus, 270 & pl. xx.

mammillaris, 271-72 & pl. xxii.

mortont, 272-73 & pl. xxii.

polygyrus, 268 & pls. xx—xxi;

var. concentricus, 269; var. mar-

ginalis, 269 & pl. xxi; var. sulcatus,

270; geol. range of, 270.

rugosus, 272 & pl. xxii.

Ptychoparia (Inostracus) ? dubia, sp.
nov., 295-96 & pl. xxv.

—-- (—) pulchella, sp. nov., 293-04
& pl. xxvi.

-—— (—) spp. indet., 294-95 & pl.
XXV1.

Puriton, see Dunball!.

GENERAL INDEX.

[Nov. 1911,

Pwll-y-glo Gronp(=Caradocian pars),
in N.E. Montgomeryshire, 419 et
seqq., 425, 426 w. list of foss.

Quarry-Ridge Beds (Cambrian), 283
et segg., 297.

Quartz in Monmouthshire monchi-
quite, 466.

Quartz-chert gravels (Oligocene ?) of
N. Egypt, 146.

Quartzite, slickensided, fr. N. Mal-
vern,v; quartzites assoc. w. Skomer
Vole. Series, 207-208.

Qena, Wadi (Egypt), Cretaceous of
area, 120-23, 128, 129-30.

Radiolaria (?) in Avonian limests. of
Burrington Combe, 346.

Radiolarian cherts in Postdonomya
Zone of Gower, 495; radiolarian
phase (cherty lagoon - phase) of
Gower, 519-24; differ. betw. Modi-
ola phases & do., 524-25; radiolar.
earth, petroliferous, in Barbados,
693.

Radstock area (Somerset), Rheetic, &e.
of, 65-67; foss. found in Coal
Measures of, 322-24, 327 ect seqq.

RanpDauu, J., obituary of, Mii.

Rangifer tarandus, iii.

Rastatu, R. H., the Geology of the
Districts of Worcester, Robertson,
& Ashton (Cape Colony), 701-82
figs. & pl. li (geol. map).

Ravenstonedale (& Cautley), Salopian
rocks of, 215-87 figs. & pl. xii (geol.
map).

Rawthey, R., Wenlock Beds of dis-
tricte ol J—2o0.

Red clays assoc. w. Skomer Vole.
Series, 207-208.

Red-Sea area, recent deposits & their
bearing on origin of Brit. Trias,
238-62 figs. & pls. xili—xvi.

Repsep Pasha, 577.

Reep, F. R. C., 300.

Rep, C., iv.

Resolven (Glamorgan), Lamproptilia
fr. Coal Measures near, 170+72 &

lise:

Beoene S. H. (& A. Vaughan),
Faunal & Lithological Sequence in
the Carboniferous Limestone Series ©
(Avonian) of Burrington Combe
(Somerset), 342-92 figs. & pls.
XXVIi1-XXX1.

Rhetic (& contiguous) deposits of
W., Mid, & part of E. Somerset,
1-74 figs. & pls. i-iv; Rheetic in
S. Notts, 79.

Rheetian, term suggested, 73, 74.

Vol. 67. |

Rhayader (Radnor), Ordovic. suc-
cession, compared w. that of Welsh-
pool, 445-46.

Rhinoceros antiquitatis, 111.

Rhondda No.2 Seam (Pennant Series),

. insect-remains from, 151 e¢ segq.

Rhyolites (& soda-felsites) of Skomer,
185-90 figs. & chem. anals. ©

Ricuarpson, L., the Rhetic & Con-
tiguous Deposits of West, Mid, &
part of East Somerset, 1-72 figs. &
pls. i-iv, 74.

Robertson district (Cape Colony),
geol. of, 714-18 et seggq.

Robin Hood’s Bay (Yorks), iv.

Robin Hood's Hills (Notts), Permian,
&e. of district, 84-86 et segq.

Rogszrs, A. W., 701, 732.

Romanss, J., [exhibits Strongylocen-
trotus-bored slate], iv.

Rostellaria sp. (Priabonian), 640 &
pl. xlvi.

‘ Rottenstones’ in Avonian of Gower,
491, 493.

Rows, A. W., Lyell medal awarded
to, xlv—xlvii.

Row egy, F. R.,399.

Rush (Dublin), correlat. of Avonian
sequence confirmed, 381; do. cor-
rel. w. that of Bristol & Gower,
552.

St. Audrie’s Slip (Somerset), sect.
deser., 21-26.

St. Brelade, see Jersey,

St. Ishmael’s (Pembroke),
184.

Salopian rocks of Cautley & Raven-
stonedale, 215-37 figs. & pl. xii
(geol-map) ; of N.E. Montgomery-
shire, 419 e segq.

Salt (& gypsum) in Red-Sea area,
251-58.

182,

Sands (& marls) in Red-Sea area, 244
et seqq. figs. ; effects of wind-blown
sand ibid., 248-49 & pls. xiv-xvi;
origin of sand zbid,, 250-51.

Santonian, see Senonian.

Sarsella lamberti, sp. nov., 675-77 &
pl. xlvii.

SaunpDErRs, —, 399.

Saxony, Geol. Surv. map presented,
Vii.

Schizaster ederi, sp. nov., 674-75 fig.
& pl. xlvii.

rimosus, compared w. Sch. ederi,
674 fig.

Scuwarz, E. H. L. [S. African evi-
dence for planetismal hypothesis],
vil.

GHNERAL INDEX.

791

Scotland, Geol. Surv. aps presented,
ll, Vil, XCv.

Scotland Series of Barbados, 693-94.

Scuteila tenera, 665-66.

sp. (Miocene), 666-67.

Sefstré6m Glacier, see Spitsbergen.

Seismographic record exhibited, vii.

Selworthy outlier (W. Somerset),
Ed

Seminula Zone at Burrington Combe,
344-47, 369-70 ; in Gower, litholog.
chars. of, 487-89, 498, 502-508 ;
faunal lists fr. do., 547-48.

Seminula ct. ambigqua, 546.

Senonian in Egypt, 119 ec seqq.

Shallowing of Carb. Limest. sea, 349 ;
see also Lagoon-phases.

SuE.eY, Capt. C. E., obituary of, liv.

Shelve (Shropshire), Ordovic: con-
trasted w. that of Welshpool area,
444.

Shepton-Mallet & Uphill area (Somer-
set), Rhetic, &c. of, 55-61.

SuerBorn, C. D., xii, 893, 399.

Sueriock, R. L., 541; the Relation-
ship of the Permian to the Trias in
Nottinghamshire, 75-117 figs. &
pl. v (geol. map).

Shoot-Rough Road Beds (Cambrian),
2838 et segg., 296, 297.

Srpty, T. F., [on Avonian of Bur-
rington Combe], 392.

Silene (Cyrenaica), 589, 591.

Silurian of N. E. Montgomeryshire,
431-42 figs. & lists of foss.; see also
Llandovery, Salopian, gc.

Sinai (E.*, sect. at Jebel Gunna deser.,
120.

Srveu, J., iil.

Sismondia, see Callianassa.

Skomer Volcanic Series (Pembroke-
shire), 175-214 figs. & pl. xi (geol.

map).

Skomerites, 196-97 fig.

Slonta (Cyrenaica). traverse to Mersa
Susa, 583-86 w. sect. ; do. to Messa,
587; forams., &c. in limest. fr.
district, 657; Slonta Limestones,
579 et segg., 593 et seqg., 600.

Snouscu, M. N., 577.

Smatt, H. W., 212; [on Skomer Vole.
Series], 213-14.

Smalls Is. (Pembroke), 175, 184.

Sain, B., [exhibits specims. of Trias-
sic sandst., &c.], v.

Snake Lane (Bagley), sect. deser.,
53.

Soda-rhyolites (& felsites) of Skomer,
185-90 figs. & chem. anals.; soda-
trachytes iid., 190-93 figs. & chem.
anals.

752 GENERAL INDEX.

Soils, Cyrenaiean, composit. of, 612-
13 w. chem. anals.

Souuas, W. J., 476.

Somerset (W., Mid, and part of E.),
Rhztic & contiguous deposits of,
1-74 figs. & pls. i-iv.

are term suggested, 73,

Somerton-Langport area (Somerset),
Rhetic, &e. of, 49-50.

South Liberty Colliery (Bedminster)
sect. deser. & fig., 317-20; foss.
from, 325 et seqq.

South Wales coalfield, insect-remains
from, 149-74 & pls. vii-x; S. W.,
Ordovic. compared w. that of
Welshpool area, 445; sce also
Gower, &c.

Sparkford - Hill area (Somerset),
ee &e. of, 45-49; map & sect.,

“Ze

Spear-head (palxolithic?), exhibited,
XCix,

Special General Meetings, viii, cii.

Speedwell Deep Colliery (Glos.), foss.
found in, 3820-21, 332 et seqq.

Spen Gill (Ravenstonedale) Ludlow
Beds of, 230: Spengillroad Gills,
do., 229-30.

Spherulitic rhyolite of Skomer, 187-
89 fig.

Spirifer bisulcatus, var. oystermouth-
ensis nov., 562 & pl. xli.

calcaratus, 562 & pl. xii.

—— cinctus, 545.

near zncrebescens, 562-63 & pl.

xli.

ef. trigonalis, 546.
wickensis, sp. nov., 563-64 & pl.

xli.

Spiriferina ef. octoplicata, 384-85.

Spirorbis pusillus as the food of blat-
toid insects, 172.

Spitsbergen, lecture on, & shells fr.
moraine exhibited, iv.

Spondylus cisalpinus, 630-31 & pl.
xliv.

sp. (Priabonian), 646.

Sponge-spicules in Avonian limests. of
Burrington Combe, 346.

Spongiostroma (¢) in Avonian limests.
of Burrington Combe, 345 & pl.
XXViil.

Staithes (Yorks), iv.

Standard Limestones (in Avonian of
Gower), 484-85, 487, 488-89.

Steam-cavities, sce Ocellar.

Sreppine, W. P. D., [exhibits pho-
togrs. of old relief-maps], v.

Stoke Road, see Exeter.

Stoxgs, A. H., obituary of, lvi—lvii.

[Nov. 1911,

Stone-Easton outlier (Somerset), 68-69.

Srrauan, A., 173, 541; [delivers
lecture on Spitsoergen], iv; re-
elected Treasurer, xxiii.

Strepsodus sauroides, 336.

Streptelasma (¢) aff. breve, 455 & pl.
XXXVi.

Strombus cf. coronatus, 626 & pl.
xliii.

Strongylocentrotus-bored slate, iv.

StupHoumeE, W. P., 399.

Sully Beds (Lr. Rheetic), 5, 10 e
seqq.

Sun Bed (Langport Beds), 28, 33, 40,
45 et seqq.

Swansea 4-foot Seam (Upper Coal-
Measures), insect-remains from, 151
et seqq.

Sweden, rock-specims. exhibited, iv;
Geol. Surv. maps presented, xcvii.

Swellendam-Worcester Fault, age &
origin of, 725 et segq.

Syntaxis of folds in .S.W. Cape
Colony, 725-27 w. map.

Syringopora cf. geniculata, 558.

Syringothyris Zone at Burrington
Combe, 348-49 ; in Gower, litholog,
chars., &c. of, 482-87, 497-98, 501-—
502; faunal lists fr. do., 546-47.

Syringothyris laminosa, 383-84 & pl.
SEKI

ef. laminosa, 540.

subconica, compared w. S. lami-

nosa, 384.

Table Mountain Series (== Lr. De-
vonian or Silurian), 702, 705 e¢
segg., 714 et seqq., 721, 728 et seqq. ;
thickness of, 731.

Tarannon Shales, equivalents in N.H.
Montgomeryshire, 419 e¢ segq.

Tea-green Marls, see Keuper.

troyivin, dla a IELy Ie}, abl.

Tectonic geology of Cyrenaica, 603—_
608 w. map.

TRILHARD DE CHARDIN, P., 278, 280.

Terrestrial period (in cycle of deposi-
tion), Ixviti-lxx1.

Tertiary, see Kainozoic.

Teschenite of Bartestree cp. w. Mon-
mouthshire monchiquite, 474—75.
Thalassic poriods (in cycle of de-

position), Ixvii, Ixxi1.

Thames Valley (Upper), palzoliths
from, lv.

Tuomas, H. H., 476; the Skomer
Volcanic Series (Pembrokeshire),
175-212 figs. & pl. xi (geol. map),
214; [on Ordovie., &e. of Welsh-
pool area], 458-59.

Vol. 67.]

Three-Arch Bridge (Shepton Mallet),
sect. in ry.-cuttg. deser., 59-60.

Thrust-phenomena in Perm. of N.
Durham, 313 ef segq.

Trppeman, R. H., Murchison Medal

awarded to, xlii—xliii.

Time-planes, geological, lxviii e¢ segq.

Toad Vein (Bristol coalfield), 319
et seq.

Tokra fault-scarp (Benghazi), 593,
601, 614.

Tor-gro (Gower), pitted pseudo-
breccia at, 499 & pl. xxxviii; un-
dolomitized pseudobreccia at, 507
et segq. & pl. xxxvili.

Tortonian - Helvetian mollusca of
Cyrenaica, 625-28 & pl. xliii; ‘see
also Kainozoic.

Tournaisian of Burrington Combe.
348-52; faunal notes on do., 363-
68.

Trachycardium cf. granconense, 646—
47.

Trachytes, soda-, of Skomer, 190-93,
figs. & chem. anals.

Trawscoed Rough (Montgomery),
Ordovie. of, 427 ; list of foss. from
do., 429.

Treacuer, Ll., [exhibits paleoliths],
iv.

Trecumann, C. T., 315.

Trefgarn (Pembroke), vele. series of,
182

Trelydan (Montgomery), Ordovice. of.
423 et segg.; ‘Wenlock Shales of,
436.

Trias (British), origin of, ii; con-
siderats. bearing on do., 238 et
segg.; Trias in relat. to Permian
of Notts, 75-117 figs. & pl. v
(map); see aso Bunter, Keuper.

Trilobites fr. Paradoxides Beds of
Comley, 282-300, 306-309, 310-11
& pls. xxili-xxvi; see also Agnostus,
&e.

Trilobite-Dingle Group (= Glenkiln-
Hartfell Group), in N.E. Mont-
gomeryshire, 419 et segg., 422-24
w. list of foss.

Trinidad (B.W I.), Kainozoic, &e. of,
696-98 fig.

Trinucleus intermedius, sp. nov., 449—
50 & pl. xxxvi.

Trorrmr, J., 577.

Trust-funds, statement of, xxxvili—
MAKIN

Tuffs (rhyolitic) of Skomer, 185.

Tunisia, Kainozoic sequence cp. w.
that of Cyrenaica, 601-603.

Turonian in Hgypt, 119 et segg.

Turcusr, J. W., 173.

GENERAL INDEX.

753

Twine Hill (Somerset), Lr. Lias, &e.
of, 61.

Tyn-y-llwyn (Montgoinery), Wenlock
Shales of, 437.

Tyning Batch (Radstock), foss. found
on spoil-heap at, 522 e¢ seqgq.

Unie, V. K., decease announced, ci.

Uitenhage Series, westernmost ex-
posure of marine facies, 721.

Um-Esh range (Egypt), 239, 251, &e. ;
gully in, pl. xiii.

Um-Hamaiet sub-type of Egyptian
Cretaceous, 130.

Um Shersher (Egypt), 129.

Umzigga, Wadi (Cyrenaica), 582;
foraminifera, &c. in rocks from,
655.

Unconformity, betw. Cretac. & Hoe.
in N. Hgypt, 145; betw. Middle &
Lr. Cambrian of Comley, 298-99.

Uniformitarianism, use of principles
of, lxiii et segg.

Uphill-Shepton-Mallet area (Somer-
set), Rhetic, &e. of, 55-61.

Uplift, epeirogenic & orogenic con-
trasted, Ixvi.

Upper Limestone Shales (D,-D,) of
Gower, 489, 491-94.

Valentian of N.E. Montgomeryshire,
419 et seqq.

Vallis Vale (Somerset), sect. deser.,
54

Vasum cf. frequens, 641 & pl. xlvi,

Vauauan, A. (& S. H. Reynolds),
Faunal & Lithological Sequence in
the Carboniferous Limestone Series
(Avonian) of Burrington Combe
(Somerset), 342-92 figs. & pls.
Xxvill-xxxi; (& EH. E. L. Dixon),
the Carboniferous Succession in
Gower (Glamorganshire), with
Notes on its Fauna & Conditions
of Deposition, 477-567 figs. & pls.
XXxVlii—xli.

Vein-dolomites, different. fr.
temporaneous dolomites,’ 481.

Venezuela (S. Am.), physiogr. hist. of
portions of, 695-96, 700.

Vindobonian, see Helvetian-Tor-
tonian,
Viséan of Burrington Combe, 344—
48; faunal notes on do., 368-71.
Vobster area (Somerset), Lr Coal-
Measures of, 321-22.

Voat, B., [receives Wollaston Medal
for W. C. Brogger], xlii.

Volcanic series of Skomer, 175-214,
figs. & pl. xi (geol. map); vole,

‘con-

Voa4 GENERAL INDEX.

craters, remnants of, in Antigua,

690; see also Leneous rocks, Lavas,

Sc.

Vulceanicity, in connex. w. earth-imove-
ments, Ixxxviii-lxxxix ; phenomena
of, in Antiguan area, 690-691.

Vulsella sp. (Priabonian), 645 &
pl. xlvi.

cf. eymari, 645-46.

Waai Kloof (Cape Colony), ottrelite-
schist of, 707, 712-14.

Wane, A., some Observations on the
Hastern Desert of Egypt, with
Considerations bearing upon the
Origin of the British Trias, 288-
61 figs. & pls. xili—xvi, 261-62 ; the
Llandovery & Associated Rocks of
North - Eastern Montgomeryshire,
415-57, 459 figs. & pls. xxxiii-
XXXVi.

Wadhurst Clay, see Wealden.

Wadi Qena, &c., see Qena, &c. r

Wadis in Cyrenaica & poss. variats.
in Pleistocene climate, 608-12.

Wage (Somerset), 50.

Wales (S.), see South Wales.

Watt, G P. [on geology of W.
Indies, &e.], 700.

Wandale Hill (Cautley district),
Wenlock Beds of, 223-27 w. sect.
& list of graptolites; Ludlow Beds
of, 229-30 w. list of graptolites.

Warranp, W. E., Gen., obituary of,
liv.

Warren, 8. H., [exhibits specims.
showg. accidental chipping of
flint], iv; [exhibits wooden palxo-
lithic (?) spear], xcix.

Warren Farm (Somerset), sect. at. 12,
13 fig. & pl. iv.

Warsop (Notts), Permian, &c. of
district, 93. .
Watchet district (Somerset), Rheetic,
&e., of, 11-380 fig. & pls. i-iv;
Watchet Beds(Upper Rhetic), 8, 9,

10 et seqg.

Waterstones (Keuper) in S. Notts,
79; see also Trias.

Watney, (Miss) G, R., (& Miss EH. G.
Welch), the Zonal Classification of
the Salopian Rocks of Cautley &
Ravenstonedale, 215-36 figs. &
pl. xii (geol. map).

Warson, Rev. R. B., obituary of, liv.

Warts, W. W., 260, 457; re-elected
President, xxiii; [exhibits plans
of new R. 8. M.], v; addresses to
recipients of Medals & Funds, xli
et segg.; obituaries of deceased
Fellows, lii-lx; [on transference

[Nov. torr,

of Geol. Soc. Museum |, Lx-lxii ; on
Geology as Geographical Evolution,
Ixti—xeiil.

Waulsortian phase (Avonian), 367
et seqq.

Wealden of Hastings, Mammalian
teeth from, 278-81 fig.

Weathering by wind-blown sand,
248-49 & pls. xiv—xvi.

Wedmore inlier (Somerset), 53-55.

We cu, (Miss) E. G., (& Miss G. R.
Watney), the Zonal Classification
of the Salopian Rocks of Cautley &
Ravenstonedale, 215-36 figs. &
pl. xii (geol. map).

Wells (Somerset), Milton-Lane sect.
deser., 57-58.

Welshpool (Montgomery), Llan-
dovery & assoc. rocks of district,
415-59 figs. & pls. xxxili-xxxvi w.
lists of foss., chem. anals., &e.

Wenlock Beds of Cautley area, 21'7—
27 w. lists of foss.,. 231-383; of
N.E. Montgomeryshire, 419 e¢ seqq.,
436-39 w. maps & lists of grapto-
lites (441-42).

Wernffraith Seam (Upper Coal-
Measures), insect-remains from,
151 ef seqq.

West Gill, see Bluecaster.

West Indies, see Antigua, Barbados,

Ge.

Westbury Beds (Lr. Rheetic), 5-7.
Westmorland & Cumberland, relat.
of Permian to Triassic, 103-105.
Westphalose (Skomer rhyolite),

190

Westwood (Devon), list of Culm. foss,
from, 398.

Wuipsorne, Rey. G. F., obituary of,
lyili.

White Lias, 2, 3 et segg., 9; see also
Langport Beds.

‘White & Red Sandstones’ (Magnesian
Limestone), 87 et seqq. figs.

Wickes, W. H.. 642.

Willhayes Copse (Devon), 397.

Wiuuiams, A. H., [exhibits Millstone
Grit boulder fr. Hertford Drift], c.

Wind-blown sand, erosive effects of,
in Red-Sea area, 248-49 & pls. xiv—
Xvi.

Windmill-Hill Quarry (Butleigh),
sect. deser., 38-39.

Wirtners, T. H., 399.

Witteberg Series (= Devono-Carbon-
iferous), 702, 715 et segq., 720, 723
ef seqg.; thickness cf, 731.

Wo tuasion Medal awarded to W. C.
Brogger, xli-xlii; W. Fund, award
to O. T. Jones, xlix; W. Medallists,

Se

Vol. 67.]

list of, xxvi ; recipients of W. Fund,
list of, xxvii.

Wolve Kloof (Cape Colony), granite,
&e. of, 715, 716-18.

Woodah, see Doddiscombsleigh.

Woodbridge Hill (Guildford), seismo-
graphic recor, vii.

Woopwarp, A. S., 274; [on recent
excavations at La Cotte cavern,
Jersey], iii; re-elected Secretary,
xxlil; [exhibits specims. of P%.
decurrens fr. Glynde], xcv; [on
phylogeny of Ptychodus|, 276; on
some Mammalian Teeth from the
Wealden of Hastings, 278-80 fig.,
281.

Wootacort, D., the Stratigraphy &
Tectonics of the Permian of
Durham (Northern Area), 312-13,
315.

Worcester district (Cape Colony),
geol. of, 704-14 et seqq. figs. & pl. li
(geol.map); Worcester-Swellendam
Fault, age & orig. of, 725 et seqq.

Y Frochas (Montgomery), Ordovic.
of, 425; list of foss. fr. do., 426.

GENERAL

INDEX. 795

Yellow Sands (Permian) in N.
Durham, 312 e seqq.

Yorkshire, relat. of Permian to
Trias in, 96-98, 112 ; see also Robin
Hood's Bay, ge.

Youne, G. W., elected Auditor, vi.

Yr Allt Group (=Ludlow), in N.4.
Montgoweryshire, 419 e¢ seqq., 439-
40 w. list of graptolites.

ZANGWILL, L., 577.

Zaphrentis delanowei, 364, 372.

—— densa, 373 & pl. xxx.

enniskillent, p. 554 & pl. xl.

—— konincki, 373; mut. C,, 546.

omaliusi, 373.

oystermouthensis, sp.nov., 5538-55

figs. & pl. xl.

ef. parallela, 372 & pl. xxx.

vaughai, 364.

Zaphrentis Zone at Burrington
Combe, 349, 363-65 ; physiograph.
comparison w. other areas, 387; in
Gower, 482, 497, 500-501; faunal
lists fr. do., 544-45.

Zeit Bay (Red Sea), saline muds, &c.
of, 244 et seqq.

Zwartebergen Folds, 730.

END OF VOL. LXVII.

PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET.

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SESSION 1910-1911.

November 9th, 1910.

Prof. W. W. Warts, Sc.D., M.Sc., F.R.S., President,
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Herbert Arthur Baker, B.Sc., Heath Lodge, Plumstead Common,
Plumstead, S.E.; Arthur Henry Noble, B.A., Geological Survey,
28 Jermyn Street, S.W.; Harry Benedict Wall, 8 Clarence House,
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Geological Society,

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VOL. LXVII.

a PROCEEDINGS OF THE GEOLOGICAL society. [Feb. git,

The following communications were read :—

1. ‘ The Rheetic and Contiguous Deposits of West, Mid, and Part
of Kast Somerset.’ By Linsdall Richardson, F.R.S.E., F.LS.,
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2. ‘Jurassic Plants from the Marske Quarry.’ By the Rev.
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The following specimens, photographs, and maps were ex-
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Specimens of Rheetic deposits and fossils from Somerset, also
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A series of photographs of Jurassic plants from the Marske
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Photographs demonstrating the recession of the Grand Pacific
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The new Geological Survey maps of Egypt, that on the scale
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J: 2,000,000 in one sheet; issued by the Survey Department
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Fourteen sheets of the 6-inch Geological Survey Map of Scot-
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November 25rd, 1910.

Prof. W. W. Warts, Sc.D., M.Sc., F.R.S., President,
in the Chair.

Charles Moncrieff Piachaud Wright, c/o Messrs. Grindlay & Co.,
55 Parliament Street, S.W., was elected a Fellow of the Society.

The List of Donations to the Library was read.

The following communications were read :—

1. ‘The Effects of Secular Oscillation in Egypt during the
Eocene and Cretaceous Periods.’ By William Fraser Hume,
D.Sc., A.R.C.S., F.G.S., Director of the Geological Survey of
cw

‘The Origin of the British Trias.’ By A. Re Horwood:
ee by Brotsa. Ge Bomney, sc.) F.RS., F.G.8.)

1 Withdrawn by permission of the Council.

Vol. 67.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY, ill

The following specimens, etc. were exhibited :—

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Rock-specimens, photographs, and lantern slides, exhibited on
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December 7th, 1910.

Prof. W. W. Warts, Sc.D., M.Sc., F.R.S., President,
in the Chair.

Frederick Robert Bader, M.Inst.C.E., Public Works Department,
Bombay (India); Alfred William Vincent Crawley, Kilo (Belgian
Congo), vid Fort Portal (Uganda); Francis A. Holiday, A.R.C.S.,
Caledonian House, Port of Spain, Trinidad (B.W.L.); Brees van
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Richey, B.A., Demonstrator in Geology in the University of Oxford,
University Museum, Oxford; William Wilfred Samuel, Tanlan
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the Society.

The list of Donations to the Library was read.

Dr. A. 8. Woopwarp communicated an account of recent excava-
tions in the cavern of La Cotte, St. Brelade’s Bay (Jersey), made
during the present year by the Jersey Society of Antiquaries.
According to the report of Mr. E. T. Nicolle and Mr. J. Sinel,
shortly to be published by the Jersey Society, the cave has yielded
evidence of human habitation and traces of Pleistocene Mammalia.
About a hundred flint-implements of the Mousterian type have been
obtained, besides part of a molar of Rhinoceros antiquitatis, and both
teeth and antlers of Rang? fer tarandus. Human remains and teeth
of Bos have also been examined and determined by Dr. C.W. Andrews
and Dr. A. 8. Woodward, to whom the whole of the collection of
mammalian remains was referred. This being the first discovery
of typical Pleistocene Mammalia in the Channel Islands, the Jersey
Society hopes to proceed with the excavations as soon as possible.

OR OR a SRR at

Iv PROCEEDINGS OF THE GHOLOGICAL society. [Feb. 1911,

Dr, A. Srranan, F.RS., Treas.G.8., delivered a lecture, illustrated
by lantern-slides, on the occurrence of recent shelly boulder-clay
and other glacial phenomena in Spitsbergen.

The following specimens, etc. were exhibited :—

Shells from the moraine of the Sefstrom Glacier, Spitsbergen,
exhibited, in illustration of Dr. A. Strahan’s lecture, by G. W.
Lamplugh, F.R.S., F.G.S.

A large series of flints, supposed to show human workmanship,
from Ipswich and district, from below the Crag of Newbournian
age, exhibited by J. Reid Moir.

Koliths, etc., and water-colour drawings of the same, exhibited
by Benjamin Harrison (Ightham).

Chipped flints from the bed at the base of the Norwich Crag,
near Norwich, exhibited by W. G. Clarke.

Paleolithic implements from one pit in the Upper Thames
Valley, exhibited by L. Treacher, F.G.S.

Eoliths from Dewlish, exhibited by C. J. Grist, M.A.

A series of evolutionary forms of eolithic and paleolithie
implements from Kent, and microliths from beneath Boulder Clay
at Acton (Suffolk), exhibited by F. J. Bennett, F.G.S.

Specimens showing the accidental chipping of flint, exhibited by
S. H. Warren, F.G.S.

Flakes broken off flint by a cart-wheel at Hedley Lane, 1893,
exhibited by E. T. Newton, F.R.S., F.G.S.

Specimens of calcareous alge showing their importance as
rock-building organisms, exhibited by Prof. E. J. Garwood, M.A.,
Sec.G.8.

Plants from the Lignite of Bovey and Heathfield (Devon) figured
and described by Mr. and Mrs. Clement Reid, exhibited by the
Director of H.M. Geological Survey.

Radioles of Triassic KEchinoids, with drawings of their micro-
structure, by G. T. Gwilliam, F.R.A.S., exhibited by Dr. F. A.
Bather, MCA., HOR:S:, E.G:S.

Specimens of Belemnites owenti from the Oxford Clay at Fletton,
near Peterborough, with pelecypods in their alveoli, exhibited on
behalf of Mr. T. Plowman by G. C. Crick, A.R.S.M., F.G.S.

Rocks from Sweden collected during excursion-meetings of the
International Geological Congress, 1910, exhibited by W. G. Fearn-
sides, M.A., F.G.S.

Slate bored by Strongylocentrotus, from Bantry Bay (Co. Cork),
exhibited by J. Romanes, M.A., F.G.S.

Block of gypsum with a groove surrounding it, from East Bridge-
ford (Nottinghamshire), exhibited by Henry Preston, F.G.S.

Fossil wood and jet in a matrix of Lias, Robin Hood’s Bay ; and
phragmocone of belemnite from Staithes, exhibited by James
Francis, F.G.S8.

Specimens of Conulus subrotundus, exhibited by G. E. Dibley,
F.G.8.

Vol. 67.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. Vv

Photographs and casts illustrating the structure of glacier-ice and
glacier granule-markings, exhibited by R. M. Deeley, M.Inst.C.E.,
F.G.S.

Lantern microscope- slides of rock-specimens, exhibited by
Dr. C. G. Cullis, F.G.S.

Autograph letters of Dean Buckland, Sir Richard Owen, and
Sir Henry De La Beche, etc., exhibited by E. A. Martin, F.G.S.

Photographs of relief-maps of the massifs of Mont Blane and
the Auvergne by L. J. Bardin, made before 1870, exhibited by
W. P. D. Stebbing, F.G.S.

Plans of the new buildings for the Royal School of Mines,
exhibited by Prof. W. W. Watts, Sc.D., F.R.S., Pres.G.S., on
behalf of the Governors of the Imperial College of Science and
Technology.

December 21st, 1910.

Prof. W. W. Warts, Sc.D., M.Sc., F.R.S., President,
in the Chair.

Thomas Henry Withers, 6 Barclay Road, Walham Green, London,
S.W., was elected a Fellow of the Society.

The List of Donations to the Library was read.

The following communications were read :—

1. ‘The Keuper Marls around Charnwood Forest.’ By Thomas
Owen Bosworth, B.A., B.Sc., F.G.S.

2. ‘ The Relationship of the Permian to the Trias in Nottingham-
shire.’* By Robert Lionel Sherlock, B.Sc., A.R.C.S., F.G.S.

The following specimens and lantern-slides were exhibited :—

Specimens from the Keuper Marls, etc., of the Charnwood
district, and lantern-slides, exhibited by T. 0. SI Ns
Pepe, UG.S., i illustration of his paper.

Specimens of Permian and Triassic rocks and lunferaeecae
exhibited by R. L. Sherlock, B.Sc., A.R.C.S., F.G.S., in illustration
of his paper.

Specimens of Triassic sandstones, etc., exhibited by Bernard
Smith, M.A., F.G.S8.

A quartzite fragment (probably from a Llandovery conglomerate
at Broomhill Path, North Malvern), polished by slickensiding ; and
tive stones presenting the characteristics of dreikanter, from the
surface of fields near Lichfield, exhibited by E. EH. L. Dixon, Be:
BY Ge

1 Communicated by permission of the Director of H.M. Geological Survey.

V1 PROCEEDINGS OF THE GEOLOGICAL sociery. [ Feb. 1911,

January llth, 1911.

Prof. W. W. Warts, Sc.D., M.Sc., F.R.S., President,’ -
in the Chair.

The following Fellows of the Society, nominated by the Council,
were elected Auditors of the Society’s Accounts for the preceding
year :—GeroreE Wittiam Youne aud CuHaries Ginperr CuLuis,

D.Se.

The List of Donations to the Library was read.

The following communications were read :—

1. ‘The Zonal Classification of the Salopian Rocks of Cautley
and Ravenstonedale.’ By Miss G. R. Watney and Miss E. G.
Welch. (Communicated by J. E. Marr, Se.D., F.R.S., F.G.S.)

2. ‘On a Collection of Insect-Remains from the South Wales
Coalfield.’ By Herbert Bolton, F.R.S.E., F.G.8., Curator of the
Bristol Natural History Museum.

The following specimens and map were exhibited :—

Tnsect-remains from the South Wales Coalfield, exhibited by
H. Bolton, F.R.S.E., F.G.S., in illustration of his paper.

Carte géologique des Hautes-Alpes calcaires entre la Lizerne et
Ja Kander, par Maurice Lugeon, on the scale of 1: 50,000, 1910,
presented by the Author.

January 25th, 1911.

Prof. W. W. Warts, Sc.D., M.Sc., F.R.S., President,
in the Chair.

Philip Grimley, 15 Hermitage Road, Edgbasten, Birmingham ;
Edward Heron-Allen, F.L.8., F.R.M.S., 3 Northwick Terrace,
N.W.; Frank Garfield Penman, M.A., Invergarry, New Barnet ;
Herbert Gladstone Smith, B.Sc., Assoc.R.C.S8., Demonstrator
in Geology in the Imperial College of Science and Technology,
85 Lancaster Road, Notting Hill, W.; Walter Campbell Smith,
B.A., British Museum (Natural History), Cromwell Road, South
Kensington, S8.W.; and William Trenna Walker, B.Sc., Wallasey
Villa, Wallasey Road, Liscard (Cheshire), were elected Fellows of
the Society.

The List of Donations to the Library was read.

Vol. 67.] PLOCEEDINGS OF THE GEOLOGICAL SOCIETY. vil

The following communication was read :—

1. ‘The Skomer Volcanic Series (Pembrokeshire). By Herbert
Henry Thomas, M.A., B.Sc., F.G.S.

The following specimens, lantern-slides, and maps were ex-
hibited :—

Specimens, rock-sections, and Jantern-slides, exhibited by H. H.
Thomas, M.A., B.Sc., F.G.S., in illustration of his paper.

Lantern-slides, illustrating South African evidence for the
planetismal hvpothesis, exhibited by Prof. E. H. L. Schwarz,
Assoc.R.C.8., F.G.S.

A record of a period of great seismic activity, January 2nd-
4th, 1911, as registered at the Station at Woodbridge Hill, Guild-
ford, exhibited by F. Edward Norris, F.G.S.

Geological Survey of Scotland: 6-inch Map, Sheet 32 (Edinburgh)
and Sheet 33 (Haddington), 1910; also l-inch Map, Sheet 71
(Glenelg), 1910, presented by the Director of H.M. Geological
Survey.

Geologische Uebersichtskarte des Kdénigreichs Sachsen, i. M.
1:500,000, von Hermann Credner, 1910, presented by the Author.

At 7 P.m., before the Ordinary Meeting, a Special General Meeting,
at which 92 Fellows were present, was held, in order to consider
the following resolutions submitted to them by the Council :—

1. That the space now occupied by the Museum be made ayailable: for the
extension of the Library.

2. That it is desirable that the Society’s collections of Fossils, Minerals,
and Rocks, with certain exceptions to be subsequently specified, be
offered to one or more of the National Museums, provided that
guarantees be obtained that the specimens will be properly registered
and rendered available for scientific purposes.

3. That itis not desirable that the Society shouid accept money for any
part of the collections, or in consideration of them.

4. That the Council be empowered to approach such Institution, or Insti-
tutions, with a view to carrying the above Resolutions into effect, and
that the Council shall call another Special General Meeting to
express approval or otherwise of the arrangement proposed.

Resolutions 1, 2, and 4 were carried unanimously, and Resolu-
tion 3 was carried by 57 Ayes to 10 Noes,

‘ Communicated by permission of the Director of H.M. Geological Survey.

vill PROCEEDINGS OF THE GEOLOGICAL society. [| Feb. rg1t.

February 8th, 1911.

Prof. W. W. Warts, Sc.D., M.Sc., F.R.S., President,
in the Chair.

Robert Boyle, B.Sc., Assoc.M.Inst.C.E., Fernlea, 8 Parkhill
Drive, Rutherglen; G. Whitfield Halse, B.Sc., c/o Edgar A. Wallis,
Apartado de Correos 416, Caracas (Venezuela) ; John Humphreys,
M.D., F.L.S., 26 Clarendon Road, Edgbaston, Birmingham ;
Herbert Louis Krausé, Afrikander Proprietary Mine, Klerksdorp
(Transvaal); and Herbert George Robins, 2 Raymead Villas,
Malling Road, Snodland (Kent), were elected Fellows of the .
Society.

The List of Donations to the Library was read.

Prof. T. W. Everwortn Davin, C.M.G., D.Sc., F.R.S., F.GS.,
gave an account of the researches pursued by him in. conjunction
with Mr. R. E. Priestley, Geologist to the British Antarctic Expe-
dition of 1907-1909, in the course of that Expedition, more
especially the investigations connected with Glacial Geology. ‘The
lecture, which was illustrated by a series of beautiful lantern-
slides and by numerous rock-specimens collected from the Antarctic
continent, was followed by a Discussion, in which Sir Ernest
Shackleton, Prof. P. F. Kendall, Mr. G. W. Lamplugh, Mr. Clement
Reid, Dr. Tempest Anderson, and Prof. E. J. Garwood took part.

ANNUAL GENERAL MEETING,

February 17th, 1911.

Prof. W. W. Warts, Sc.D., M.Sc., F.R.S., President,
in the Chair.

Report oF tHe Counctn For 1910,

Tue Society shared in the national mourning occasioned by the
untimely decease of His Majesty, King Edward VII. The Pre-
sident gave expression to the sorrow felt by the Fellows, by
postponing sie die the Meeting which had been arranged for
May 11th, 1910. At a later date, the President and Council, on
their own behalf and on that of the Fellows, presented an Address
_ to King George V, expressing their respectful condolence with him
on the death of the late Monarch, and welcoming His Majesty’s
accession to the Throne. The text of this Address, to which a
gracious reply was received, will be found at p. xcii of the Pro-
ceedings of the last Session (Q. J. G. 8. vol. Ixvi, 1910).

Although there were fewer new Fellows elected in 1910 than
during the previous year, a slight increase in the total number of
Fellows can still be recorded. In 1910, the Fellows elected
numbered 48 (as compared with 64 in 1909), and 35 of these paid
their Admission Fees before the end of the year. Moreover, 21
Fellows who had been elected in 1909 paid their Admission Fees
in 1910, making the total Accession of new Fellows during the
twelve months under review amount to 56.

Setting against this number a loss of 51 Fellows (24 by death,
18 by resignation, and 9 by removal from the List, under Bye-Laws,
Sect. VI, Art. 5), it will be seen that there is a net increase in
the Number of Fellows of 5 (as compared with an increase of 11 in
1909, and of 5 in 1908),

The total Number of Fellows is thus increased to 1299, made
up as follows:—Compounders 252 (6 less than in 1909); Con-
tributing Fellows 1025 (14 more than in 1909); and Non-
contributing Fellows 22 (3 less than in 1909),

Turning to the Lists of Foreign Members and Foreign Corre-
spondents, the Council have the rare pleasure of stating that no
losses have been experienced during the year. The two vacancies
in the List of Foreign Correspondents which were left at the end
of 1909, were in due course filled by the election of Prof. F. A.
Forel and Dr. A. E. Térnebohm, making both Lists complete.

With regard to the Income and Expenditure of the Society
during 1910, the figures set forth in detail in the Balance-Sheet
may be summarized as follows :—The actual Receipts (excluding

VOL. LXVII. b

x PROCEEDINGS OF THE GEOLOGICAL socrEry. [May 1911,.

the Balance of £178 18s. 2d. brought forward from the previous.
year and £100, the amount of the “Hannah Bequest) amounted to-
£3159 17s. 2d., being £1 5s. 2d. more than the estimated Income..
On the other hand, the total Expenditure during the same year
amounted to £2985 16s. 2d., being £101 1s. 10d. less than the
estimated Expenditure for the year and £174 1s. Od. less than
the actual Receipts, the year closing with a Balance in hand of
Sooo os. 2d.

In the course of April, 1910, a sum of £100 was received from
the executors of the late Mr. Robert Hannah, F.G.S., a bequest to:
which no restrictive conditions whatever were attached.

The Committee appointed by the Council towards the end of
January 1910, to consider the question of the transference of the
Museum, with which is bound up the greatly needed extension of
the Library, held several sittings; and, their conclusions having
been endorsed by the Council, certain resolutions of Council were
submitted to a Special General Meeting of the Fellows, held on
January 25th, 1911. The result of that Meeting, as also the full
text of the resolutions, appears on p. vii of the current Proceedings.

The Council have to announce the completion of Vol. LX VI and
the commencement of Vol. LX VII of the Society’s Journal.

The eighth Award from the Daniel Pidgeon Trust Fund was:

made on March 9th, 1910, to Mr. Robert Boy la, B.Sc., who proposed
to make a series of resear ches on the Carboniferous Building-Stones.
of Scotland.

The following Awards of Medals and Funds have also been:
made by the Council :—

The Wollaston Medal is awarded to Prof. Waldemar Christofer
Brogger, in recognition of his ‘ researches concerning the Mineral.
Structure of the Earth,’ and as a mark of esteem for one who, in an
age of specialization, has, almost alone among geologists, contributed!
brilliant and original memoirs dealing with subjects appertaining
to every branch of Geological Science.

The Murchison Medal, with a sum of Ten Guineas from the
Murchison Geological Fund, is awarded to Mr. Richard Hill
Tiddeman, in recognition of his valuable contributions to Geological:
Science, more especially in connexion with the Carboniferous and
Pleistocene formations in Britain.

The Lyell Medal, together with a sum of Twenty-Five Pounds, is-
this year exceptionally awarded in duplicate, to

Dr. Francis Arthur Bather, in recognition of his contributions:
to our knowledge of the Paleontology of the Invertebrata, and
especially of the Echinodermata ; and to

Dr. Arthur Walton Rowe, as an acknowledgment of his contri-
butions to our knowledge of the zonal sequence in the Upper
Cretaceous rocks.

The Bigsby Medal is awarded to Prof. Othenio Abel, in recogni-
tion of his contributions to our knowledge of the Paleontology of
the Vertebrata, more especially of the Cetacea and Sirenia, and to
encourage him in further research. ,

Vol. 67.] ANNUAL REPORT. xl

The Balance of the Proceeds of the Wollaston Donation Fund is
awarded to Prof. Owen Thomas Jones, as an acknowledgment of
the value of his extensive researches among the Lower Paleozoic
rocks of Wales.

The Balance of the Proceeds of the Murchison Geological Fund
is awarded to Mr. Edgar Sterling Cobbold, in recognition of his
investigations among the Lower Paleozoic rocks of Shropshire,
whereby he has been enabled to establish the sequence of the three
lowest Cambrian faunas in this country.

The Balance of the Proceeds of the Lyell Geological Fund is
awarded to Dr. Charles Gilbert Cullis, in acknowledgment of his
contributions to our knowledge of the Origin of Dolomites, and to
stimulate him in further work.

A portion of the Proceeds of the Barlow-Jameson Fund is
awarded to Mr. John Frederick Norman Green, as an acknow-
ledgment of his work on the older rocks in the neighbourhood
of St. Dayid’s, and to encourage him in further researches.

Report oF THE LIBRARY AND Museum Commirree ror 1910.

The Committee have pleasure in reporting that the Additions
made to the Society’s Library during the past twelve months have
fully maintained, both in number and in importance, the standard
of previous years.

During the year 1910, the Library received by Donation 231
Volumes of separately published Works, 296 Pamphlets, 40 de-
tached Parts of Works, also 327 Volumes and 24 detached Parts
of Serial Publications, and 25 Volumes of Weekly Periodicals.

The total number of accessions to the Library by Donation
is thus found to amount to 583 Volumes, 296 Pamphlets, and 64
detached Parts. Moreover, 176 Sheets of Geological Maps were
presented to the Library, including 65 Sheets received from the
Geological Survey of England and Wales, and 52 Sheets from that
of Scotland; 3 Sheets of the International Geological Map of
Europe; 12 Folios of the Geologic Atlas of the United States;
8 Sheets received from the Geological Survey of the State of
_ Victoria; 7 Sheets from the Geological Survey of Egypt; 7 Sheets
from the Geological Survey of Japan; 5 Sheets ‘rom the Swiss
Geological Commission ; and 5 Sheets from the Imperial Austrian
Reichsanstalt.

Among the Books and Pamphlets mentioned in the preceding
paragraph, especial attention may be directed to the following
works :—The fourth Voiume of Miss Hertha Sollas’s translation
(‘The Face of the Earth’) of Prof. E. Suess’s ‘ Antlitz der Erde’ ;
the sixth fasciculus of Dr. L. Carez’s ‘Geology of the French
Pyrenees’; Dr. F. A. Bather’s monograph on the Triassic Echino-
derms of Bakony ; twelve volumes published in commemoration cf

b2

xil PROCEEDINGS OF THE GEOLOGICAL socrETY. [May tort,

the bi-centenary of Linnzeus, presented by the University of Upsala ;
Dr. B. Lotti’s ‘Geology of Tuscany’ (vol. xii of the Memorie
descrittive della Carta geologica d'Italia); the monograph on the
Basin of the Upper Vishéra (Northern Urals), by Prof. L. Dupare
and others; the monographs on the Fossil Fishes of Northern
France and the neighbouring regions, and on the Oligocene Fishes
of Belgium, by M. Leriche; Dr. F. H. Hatch’s Report on the
Mines & Mineral Resources of Natal; Mr. H. B. Woodward’s
‘Geology of Water-Supply’; Mr. L. L. Fermor’s monograph on the
Manganese Ore-Deposits of India; Dr. Ivor Thomas’s monograph
on the Carboniferous Orthotetine ; the second volume of Prof.
J. W. Gregory’s British Museum Catalogue of the Cretaceous
Bryozoa; Dr. C. W. Andrews’s Descriptive Catalogue (British
Museum) of the Marine Reptiles of the Oxford Clay; and six
volumes of the Proceedings of the Dorset Natural History &
Antiquarian Field-Club, presented through the Rev. J. C. M.
Mansell-Pleydell. ‘The Geological Survey Memoirs on the London
District, on the Country arqund Bodmin & St. Austell, on the
Country around Basingstoke and around Alresford, on the Melton
Mowbray District, etc., on the Country around Nottingham, and on
the Country around Carmarthen, were received; as also Dr. A.
Strahan’s ‘Guide to the Geological Model of Ingleborough &
District.’ Moreover, numerous publieations were received from the
Geological Survey departments of the Cape Colony, the Transvaal,
of the various States of the Australian Commonwealth, and of
the Dominion of New Zealand; also from the Geological Survey
departments of Egypt, India, Italy, Norway, Portugal, Prussia,
Rumania, Russia, and Sweden; from the United States Geological
Survey, and from the independent State Surveys of Illinois, lowa,
Kansas, Maryland, and New York.

The Books and Maps enumerated in the foregoing paragraphs
were the gift of 151 Government Departments and other Public
Bodies; of 180 Societies and Editors of Periodicals; and of
196 Personal Donors.

The Purchases, made on the recommendation of the standing
Library Committee, included 61 Volumes and 7 detached Parts of
separately published Works; 89 Volumes and 12 detached Parts
of Works published serially ; and 22 Sheets of Geological Maps.

The Expenditure incurred in connexion with the Library during
the year under review was as follows :—

Cs eee

Books, Periodicals, ete. purchased ........ LOT Vifeies
Binding of Books and Mounting of Maps .. 149 14 8

£257 127k

Mr. C. Davies Sherborn reports that steady progress continues
to be made with the preparation of the Card Catalogue of the

Library.

Vol. 67.] ANNUAL REPORT. xill

MuseEvm.

For the purpose of study and comparison, the Society’s Collections
were visited on 22 occasions during the year, the contents of

‘74+ drawers being thus examined. The permission of the Council

having been duly obtained, some 32 specimens were lent in the
course of 1910 to various investigators.

No expenditure has been incurred in connexion with the Museum
during the past year.

The appended Lists contain the Names of Government Depart-
ments, Public Bodies, Societies, Editors, and Personal Donors, from
whom Donations tothe Library have been received during the year

,

under review :—

I. Government DEPARTMENTS AND OTHER Pustic Bopits.

Alabama.—Geological Survey. Montgomery (Ala.).

American Museum of Natural History. New York.

Argentina.—Ministerio de Agricultura. Buenos Aires.

Australia (S.), ete. See South Australia, ete.

Austria.—Kaiserlich-K6nigliche Geologische Reichsanstalt. Vienna.

Bavaria.—Konigliches Bayerisches Oberbergamt. Munich.

Belgium.—Académie Royale des Sciences, des Lettres & Beaux-Arts de Belgique,
Brussels.

—. Musée Royal d'Histoire Naturelle. Brussels.

Service géologique de Belgique. Brussels.

Bergens Museum. Bergen.

Berlin.—KOnigliche Preussische Akademie der Wissenschaften.

Birmingham, University of.

Bohemia.—Naturwissenschaftliche Landesdurchforschung. Prague.

——. Royal Museum of Natural History. Prague.

Bristol.—Publiec Library.

British Columbia.—Department of Mines. Victoria (B.C.).

British Guiana.—Department of Mines. Georgetown.

British South Africa Company. London.

Buenos Aires.—Museo Nacional de Buenos Aires.

California——Academy of Sciences. San Francisco.

, University of. Berkeley (Cal.).

Camborne.—Mining School.

Cambridge (Mass.)—Museum of Comparative Zoology in Harvard College.

Canada.—Geological & Natural History Survey. Ottawa.

, High Commissioner for. London.

Cape Colony.—Department of Agriculture (Geological Commission). Cape
Town.

—. South African Museum. Cape Town.

Chicago.—‘ Field’ Columbian Museum.

Connecticut.—State Geological & Natural History Survey. Hartford (Conn.).

Cérdoba (Argentine Republic).—Academia Nacional de Ciencias.

Cracow.—Academy of Sciences.

Denmark.—Commission for Ledelsen af de Geologiske & Geographiske Unders6-
gelser i Grénland. Copenhagen.

Geologiske Underségelse. Copenhagen. .

—. Kongelige Danske Videnskabernes Selskab. Copenhagen.
Dublin.—Royal Irish Academy.

Egypt.—Department of Public Works (Survey Department). Cairo,
Finland.—Finlands Geologiska Undersékning. Helsingfors.
France.—Ministére de la Guerre. Paris.

X1V PROCEEDINGS OF THE GEOLOGICAL SocrEry. [May 1911,

France.—Ministére des Colonies. Paris.

Ministére des Travaux Publics. Paris.

Muséum d’Histoire Naturelle. Paris.

Georgia.—Geological Survey. Atlanta (Ga.).

Germany.—Kaiserliche Leopoldinisch-Carolinische Deutsche Akademie der
Naturforscher. Halle an der Saale.

Great Britam—Army Medical Department. London.

- British Museum (Natural History). London.

Colonial Office. London.

Geological Survey. London.

Home Office. London.

India Office. London.

Holland. —Departement van Kolonien. The Hague.

Staatliche Bohrverwaltung in den Niederlanden,. The Hague.

Hull.—Municipal Museum.

Hungary.—Konigliche Ungarische Geologische <Anstalt (Magyar Féldtani
Tarsulat). Budapest.

Illinois State Museum of Natural History. Springfield (I1.).

India.—Geological Survey. Calcutta.

—. Indian Museum. Calcutta.

Surveyor-General’s Office. Calcutta.

Iowa Geological Survey. Des Moines (Iowa).

Treland.—Department of Agriculture & Technical Instruction. Dublin.

Italy.—Reale Comitato Geologico. Rome.

Japan.—Earthquake-Investigation Committee. Tokio.

Geological Survey. Tokio:

Jassy, University of.

Kansas.— University Geological Survey. Lawrence (Kan.).

Kingston (Canada).—Queen’s College.

Klausenburg (Koloszvar).—Provincial Museum & Library.

Leeds, Univ versity of.

London .—City of London College.

Imperial College of Science & Technology.

——. Imperial Institute.

—. Royal College of Surgeons.

University College.

Madrid.—Real Academia de Ciencias Exactes, Fisicas & Naturales.

Magdeburg.—Museum fiir Natur- und Heimatkunde.

Maryland.—Geological Survey. Baltimore (M4d.).

Melbourne (Victoria).—National Museum.

Mexico.—Instituto Geolégico. Mexico City.

Michigan College of Mines. Houghton (Mich.).

Milan.—Reale Istituto Lombardo di Scienze & Lettere.

Missouri.—Bureau of Geology & Mines. Jefferson City (Mo.).

Montana University. Missoula (Mont.).

Munich.—Ko6nigliche Bayerische Akademie der Wissenschaften.

Mysore Geological Department. Bangalore.

l

Naples.—Accademia delle Scienze.

Natal.—Department of Mines. Pietermaritzburg.

- Geological Survey. Pietermaritzburg.
Government Museum. Pietermaritzburg.

Newcastle-upon-Tyne.—Armstrong College.

New Jersey.—Geological Survey. Trentham (N.J.).

New South Wales, Agent-General for. London.

—. Department of Mines & Agriculture. Sydney.

——. Geological Survey. Sydney.

New York State Museum. Albany (N.Y.).

New Zealand.—Department of Mines. Wellington.

Geological Survey. Wellington.

Norway.—Norges Geologiske Undersékelse. Christiania.

Nova Scotia.—Department of Mines. Halifax.

Ohio Geological Survey. Columbus (Ohio).

Ontario.—Bureau of Mines. Toronto.

Padua.—Reale Accademia di Scienze, Lettere & Arti.

Paris.—Académie des Seiences.

Perak Government. ‘Taiping. -

Peru.—Mninisterio de Fomento. Laima.

Wol. 67.] ANNUAL REPORY. XV

Philippine Is.—Department of the Interior; Bureau ef Science. Manila.
Pisa, Royal University of.
Portugal.—Comunissao dos 'Trabalhos Geologicos. Lisbon. .
Prussia.—Konigliches Ministerium fiir Handel & Gewerbe. Berlin.
KGnigliche Preussische Geologische Landesanstalt. Berlin.
Queensland, Agent-General for. Loudon.
Department of Mines. Brisbane.
. Geological Survey. Brisbane.
Redruth.—School of Mines.
Rhodesia. —Chamber of Mines. Bulawayo.
Rhodesian Museum. Bulawayo.
Rio de Janeiro.—Museu Nacional.
Rome.—Reale Accademia dei Lincei.
Rumania.—Geological Survey. Buecarest.
Russia.—Comité Géologique. St. Petersburg.
——. Musée Géologique Pierre le Grand. St. Petersburg. ;
—. Section Géologique du Cabinet de S.M. ?Empereur. St. Petersburg.
‘Sao Paulo (Brazil)—Commissao Geographica & Geologica. Sao Paulo City.
Secretaria da Agricultura, Commercio & Obras Publicas. Sao Paulo City.
‘South Australia, Agent-General for. London.
Department of Mines. Adelaide.
——. Geological Survey. Adelaide.
‘Spain.—Comision del Mapa Geolégico. Madrid.
Stockholm.—Kongliga Svenska Vetenskaps Akademi.
Sweden.—Sveriges Geologiska Undersékning. Stockholm.
‘Switzerland.—Geologische Kommission der Schweiz. Berne.
‘Tasmania.—Secretary for Mines. Hobart. ~
‘Tokio.—Imperial University.
College of Science.
Transvaal.—Geological Survey. Pretoria.
-—. Mines Department. Pretoria.
“Turin.—Reale Accademia delle Scienze.
United States.—Department of Agriculture. Washington (D.C.).
Geological Survey. Washington (D.C.).
—. National Museum. Washington (D.C.).
Upsala, Royal University of.
‘Victoria (Austral.), Agent-General for. London.
). Department of Mines. Melbourne.
( ). Geological Survey. Melbourne.
‘Vienna.—Kaiserliche Akademie der Wissenschaften.
Washington (D.C.).—Smithsonian Institution.
‘Washington, State of (U.S.A.).—Geological Survey. Olympia (Wash.).
‘West Indies.—Imperial Agricultural Department. Bridgetown (Barbados).
Western Australia, Agent-General for. London.
Department of Mines. Perth.
Geological Survey. Perth.
Wisconsin.—Geological & Natural History Survey. Madison (Wisce.).
Yale University Museum (Peabody Museum). Geological Department. New
Haven (Conn.).

II. Societies an» Kprrors.

Acireale.—Accademia di Scienze, Lettere & Arti.
Adelaide.—Royal Society of South Australia.
Agram.—Societas Historico-Naturalis Croatica.
Alnwick.—Berwickshire Naturalists’ Club.
Basel.—Naturforschende Gesellschaft.
Bath.—Natural History & Antiquarian Field-Club.
Belgrade.-—Servian Geological Society.
Bergen.— Naturen.’

Berlin.— Deutsche Geologische Gesellschaft.
Gesellschaft Naturforschender Freunde.
‘Zeitschrift fiir Praktische Geologie.’

Berne.—Schweizerische Naturforschende Gesellschaft.
Bombay Branch of the Royal Asiatic Society.
®Bordeaux.—Société Linnéenne.

XVI

PROCHEDINGS OF THE GEOLOGICAL society. [May 191T,.

Boston (Mass.) Society of Natural History.

American Academy of Arts & Sciences.

Bristol Naturalists’ Society.

Brooklyn (N.Y.) Institute of Arts & Sciences.
Brunswick.—Verein fiir Naturwissenschaft zu Braunschweig.
Brussels.—Société Belge de Géologie, de Paléontologie & a’ Hydrologie.
. Société Royale Zoologique & Malacologique de Belgique.
Budapest.—Féldtani Koézlény.

Buenos Aires.—Sociedad Cientifica Argentina.
Bulawayo.—Rhodesian Scientific Association.

Caen.—Société Linnéenne de Normandie.

Calcutta.—Asiatic Society of Bengal.

—. ‘Indian Engineering.’

Cambridge Philosophical Society.

Cape Town.—-South African Association for the Advancement of Science.
South African Philosophical Society.

Cardiff.—South Wales Institute of Engineers.
Chambéry.—Société d’Histoire Naturelle de Savoie.

Chicago.—‘ Journal of Geology.’

Christiauia.—Norsk Geologisk Forening.

‘Nyt Magazin for Naturvidenskaberne,’
Colombo.—Ceylon Branch of the Royal Asiatic Society.
Colorado Springs.-—‘ Colorado College Studies.’

Croydon Natural History & Scientitic Society.
Denver.—Colorado Scientific Society.

Dijon.—Académie des Sciences, Arts & Belies-Lettres.

Dorpat (Jurjew).—Naturforschende Gesellschaft.
Dresden.—Naturwissenschaftliche Gesellschaft.

Verein ftir Erdkunde.

Edinburgh.—Geological Society.

Royal Scottish Geographical Society.

——. Royal Society.

Ekaterinburg.—Société Ouralienne d’Amateurs des Sciences Naturelles.
Falmouth.—Royal Cornwall Polytechnic Society.

Frankfurt am Main.—Senckenbergische Naturforschende Gesellschaft.
Freiburg im Breisgau.—Naturforschende Gesellschaft.
Fribourg.—Société Fribourgeoise des Sciences Naturelles.
Geneva.—Société de Physique & d’Histoire Naturelle.
Giessen.—Oberhessische Gesellschaft fiir Natur- & Heilkunde.
Glasgow.—Geological Society.

Gloucester.—Cotteswold Naturalists’ Field-Club.
Gratz.—Naturwissenschaftlicher Vereim ftir Steiermark.
Haarlem.—Société Hollandaise des Sciences.

Halifax (N.S.).—Nova Scotian Institute of Science.

Hamilton (Canada).—Hamilton Scientific Association.
Hanau.—Wetterauische Gesellschaft ftir Gesammte Naturkunde.
Havre.—Société Géologique de Normandie.
Helsingfors.—Société Géographique de Finlande.

Hereford.—W oolhope Naturalists’ Field-Club.
Hermannstadt.—Siebenburgischer Verein fiir Naturwissenschaft.
Hertford.— Hertfordshire Natural History Society.

Hull Geological Society.

Indianapolis (Ind.).—Indiana Academy of Science.

J ohannesburg.— Geological Society of South Africa.
Kiev.—Société des Naturalistes.

Lancaster (Pa.).—‘ Economic Geology.’

Lausanne.—Société Vaudoise des Sciences Naturelles.

Lawrence (Kan.).—‘ Kansas University Bulletin.’
Leeds.—Geological Association.

Philosophical & Literary Society.

——. Yorkshire Geological Society.

Leicester Literary & Philosophical Society.

Leipzig.—‘ Zeitschrift ftir Krystallographie & Mineralogie.
Liége.—Société Géologique de Belgique.

. Société Royale des Sciences.

Lille.—Société Géologique du Nord.

Lima.— Revista de Ciencias.’

Lisbon.—Sociedade de Geographia.

Vol 67. | ANNUAL REPORT. XVIL

Lisbon.—Société Portugaise des Sciences Naturelles.
Liverpool Geological Society.
Literary “& Philosophical Society.
London.—Association of Water Engineers.
‘The Atheneum.’
British Association for the Advancement of Science.
Chemical Society.
‘The Chemical News.’
‘The Colliery Guardian.’
‘The Geological Magazine.’
Geologists’ Association.
Institution of Civil Engineers.
Institution of Mining Engineers.
Institution of Mining & Metallurgy.
Tron & Steel Institute.
Linnean Society.
‘The London, Edinburgh, & Dublin Philosophical Magazine.’
Mineralogical Society.
‘The Mining Journal.’
‘Nature.’
Palzontographical Society.
‘The Quarry.
Ray Society.
‘Records of the London & West-Country Chamber of Mines.’
Royal Geographical Society.
Royal Institution.
Royal Meteorological Society.
Royal Microscopical Society.
Royal Photographic Society.
Royal Society.
Royal Society of Arts.
Society of Biblical Archeology.
‘The South-Eastern Naturalist ’ (S.E, Union of Scientific Societies).
Victoria Institute.
‘ Water.’
Zoological Society.
Manchester Geological & Mining Society.
Literary & Philosophical Society.
Manila.—Philippine Journal of Science.
Melbourne (Victoria).—Australasian Institute of Mining Engineers.
Royal Society of Victoria.
‘The Victorian Naturalist.’
Mexico.—Sociedad Cientifica ‘ Antonio Alzate.’
Moscow.—Société Impériale des Naturalistes.
New Haven (Conn.).— The American Journal of Science.
New York.—Academy of Sciences.
American Institute of Mining Engineers.
—. ‘Science.’
Newcastle-upon-Tyne.—North of England Institute of Mining & Mechanical
Engineers.
—. University of Durham Philosophical Society.
Northampton.—Northamptonshire Natural History Society.
Niirnberg.—Naturhistorische Gesellschaft.
Oporto —Academia Polytecnica. [Coimbra.]}
Ottawa.—Royal Society of Canada.
Paris.—Commission Frangaise des Glaciers.
Société Francaise de Minéralogie.
—. Société Géologique de France.
‘ Spelunca.’
Penzance.—Royal Geological Society of Cornwall.
Perth.—Perthshire Society of Natural Science.
Philadelphia.—Academy of Natural Sciences.
American Philosophical Society.

Hela aL

saab | WW |

|
|

pelle

Pisa.—Societa Toscana di Scienze Naturali.

Plymouth.—Devonshire Association for the Advancement of Science.
Rennes.—Société Scientifique & Médicale de Ouest.

Rochester (N.Y.).—Academy of Science.

—. Geological Society of America.

XVill PROCEEDINGS OF THE GEOLOGICAL Sociery. | May 1911,

Rome.—Societa Geologica Italiana.

Rugby School Natural History Society.

Santiago de Chile-—Sociedad Nacional de Mineria.

Société Scientifique du Chili.

Sao Paulo (Brazil) —Sociedade Scientifica.

Scranton (Pa.).—‘ Mines & Minerals.’

St. John (N.B.).—Natural History Society of New Brunswick.

St. Petersburg.—Russische Kaiserliche Mineralog ische Gesellschaft.

Stockholm. —Geologiska Forening.

Stratford.—Essex Field-Club.

Stuttgart‘ Centralblatt fiir Mineralogie, Geologie & Palaontologie.’

‘Neues Jahrbuch fiir Mineralogie, Geologie & Palaontologie.’

——. Oberrheinischer Geologischer Verein.

—. Verein fiir Vaterlandische Naturkunde in Wirttemberg.

‘ Zeitschrift ftir Naturwissenschaften.’

Sydney (N.S.W.).—Linnean Society of New South Wales.

Royal Society of New South Wales.

Toronto.—Canadian Institute.

Toulouse.—Société d’ Histoire Naturelle.

Truro.—Royal Institution of Cornwall.

Vienna.—‘ Beitrage zur Palaontologie & Geologie Csterreich-Ungarns & des
Orients.’

——. ‘Berg- & Hittenmannisches Jahrbuch.’

——. Geologische Gesellschaft.

Kaiserlich- Konigliche Zoologisch- Botanische Gesellschatt.

Washington (D.C.) Academy of Sciences.

Biolog ical Society.

—-. Philosophical Society.

Wellington (N.Z.)—New Zealand Institute.

Wiesbaden.—Nassauischer Verein ftir Naturkunde.

W orcester.—W orcestershire Naturalists’ Club.

York.—Yorkshire Philosophical Society.

IIT. Personat Donors.

Flett, J.S.
Foote, W. M.
Forel, F. A.
Fritsch, A.

Garwood, E. J.
Geikie, Sir Archibald.
Gerth, H.

Ghose, A.

Adams, F. D.
Adams, J.
Ameghino, F.
Andrew, A. R.
Andrews, E. C.
Andrusov, N.
Arctowski, H.
Armitage, R. W.
Arnold, E.

Christy, M.

Chinchi 1G.

Clough, C. T.
Cockayne, L. |
Coker, E. G. |
Cole, G. A. J. |
Collingridge, W.

Collins, J. H.

Cooper, L.

: ay
a

Arnold-Bemrose, H. H.

Arsandaux, H.

Bailey, T. E. G.
Basedow, H.
Bather, F. A.
Bennett, F. J.
Behm, G.
Boyle, R.
Branca, W.
Branner, J. C.
Breton, L.
Bullen, Rev. R. A.
Burr, A.

Cameron, A. C. G.
Carez, L.

Carus- Wilson, C.
Chandler, R. H.
Chapman, EF.
Charcot, —.
Choffat, P.

Crampton, C. B.
Cnick, Go Cal)
Cumings, E. R.

Dall, W. H.
Dalton, L. V.
Daly, R. A.
Davison, C.
Dewey, H.
Dionne, N. E.
Drygalski, E. von.
Dunn, E: J.
Dupare, L.

Egelestone, W. M.

Ellis, T. S.
Evans, J. W.

Fearnsides, W. G.
Ferrar, H. T.
Filliozat, M.
Finlayson, A. M.

Gibson, W.
Gordon, Mrs. M. O.
Grayson, J. H.
Gregory, J. W.
Grosch, P.

Habershon, M. H.
Hardwick, F. W.
Harmer, F. W.
Hateh yh Ee
Heim, A.

Jebil Jel.

Hind, W.
Hobson, B.
Hopkinson, J.
Horwood, A. R.
Horwood, C. B.
Hovenden, F.
Hovey, E. O.
Huggins, Sir Willian.
Hull, E.

Hume, W. F.

pVel; 67.|

-

Hume, W. H.
Hutchinson, Rev. H. N.

Issel, A.

Jackson, J. W.
Jentzsch, A.
Jentzsch, J.
Johnson, D. W.
Jounson, Tl. —
Jordan, H. K.
Jutson, J. T.

Kennard, A. S.
Kidner, H.

Koenen, A. von.
Krishtafovich, N. F.
Kronecker, W.

Lacroix, A.
Lamb, G. F.
Lambe, L. M.
Landes, H.
Lang, A.
Lemoine, P.
Lenicque, H.
Leriche, M.
Liebisch, T.
Louderback, G. D.
Lowerison, B.

Maitland, A. G.
Margerie, E. de.
Marr, J. E.
Martin, E. A.
Martin, L.
Maslen, A. J.
Maufe, H. B.
Mennell, F. P.
Merzbacher, G.

ANNUAL REPORT.

Monckton, H. W.
Moreno, F. P.

Nathorst, A. G.
Newton, E. T.

Ord, W. T.
Oswald, F.

| Park, Mongo.
Pavlov, (Mdme.) M. V.

Perceval, S. G.
Petterd, W. F.
Plotts, W.
Pogue, J. E.
Pollard, W.
Porto, A.
Pringle, J.
Prosser, C. 8.
Purdue, A. H.

Radley, E. G.
Reed, F. R. C.
Reid, C.

Reid, Mrs. E. M.
Ricciardi, L.
Richards, H. C.
Richardson, L.

Sabot, R.
Sauvage, H. E.
Scharff, R. S.
Schmidt, M,
Schmidt, R. R.
Schwarz, E. H. L.
Scott, D. H.
Seward, A. C.
Sheppard, T.
Sjogren, H.
Skeats, E. W.
Smith, 8.

xix

Smith, W. D.
Sollas, W. J.
Speight, R.
Spencer, J. W.
Steinmann, G.
Stevenson, J. J.
Suess, E.
Summers, R. 5.

Tait, D:

Tarr, R. S.
Termier, P.
Thompson, b.
Thomson, J.
Thoroddsen, T.
Thresh, M.
Tilho, J.
Teernquist, S. L.

Waagen, L.
Wade, A.

| Wadsworth, M. E.

Ward, L. K.
Warren, H.
Washington, H. S.
Wernert, P.
Whitaker, W.
White, H. J. O.
Wieland, G. R.
Wilckens, O.
Wilde, H.

Willis, B.
Williston, S. W.
Winwood, Rev. H. H.
Wolff, W.
Woodward, A. 8S.
Woodward, Henry.
Woodward, H. B.
Wright, F. E.
Wunder, M.

Zeiller, R.

XX PROCEEDINGS OF THE GEOLOGICAL socieTy. | May rgrt,.

CoMPARATIVE STATEMENT OF THE NUMBER OF THE SOCTETY AT THE
} ~ 4
CrosE oF THE YEARS 1909 anv 1910.

| Dec. 31st, 1909. Dec. 31st, 1910.
! Compouniders (. 2.2005. 0.) 208) it (cc ee 252
| Contributing Fellows...... OW Tinh, oN 1025
\ Non-Contributing Fellows. . A diana pl te 22
| 1294 1299
Foreign Members ........ BAAD fi Meee 40
Foreign Correspondents... .. | Ne wie 40
1372 1379

Comparative Statement, explanatory of the Alterations in the Number
of Fellows, Foreign Members, and Foreign Correspondents at the
close of the years 1909 and 1910.

Number of Compounders, Contributing and Non- 1294
Contributing Fellows, December 31st, 1909 ..

Add Fellows elected during the former year and 21
Pare. ta WP RO gC eh gee Re ee ane
Add Fellows elected and paid in 1910 ........ 3D
1350
Deduct Compounders deceased...............- 8
Contributing Fellows deceased .......... 13
Non-Contributing Fellows deceased ...... 3
Contributing Fellows resigned .......... 18
Contributing Fellows removed .......... 9
— oi
1299
\ Number of Foreign Members and Foreign Cor- re
respondents, December 3lst, 1909 ..........
Add Foreign Correspondents elected ........ 2
— 80

Vol. 67.] ANNUAL REPORT. xxi

DeEcEASED FELLOWS.

Compounders (8).

Blake, Prof. W. P. Smith, C.

Heaphy. T. M. Tendron, F.

Shelley, Capt. G. E. | Watson, Rev. Dr. R. B.
Smethurst, W. | Whidborne, Rev. G. F.

Resident and other Contributing Fellows (18).

Bird, C. Godson, G. R.
Brown, A. Klaassen, H. M.
Clark, J. F. Llewellin, W. M.
Cooke, Dr. T. Melliss, J. C.
‘Cross, E. | stokes, A. i.
Evans, Rev. de C. | Mourne.

_ Fox-Strangways, C.

Non-Contiibuiing Fellows (3).

Egerton, Prebendary W. H. Warrand, Maj.-Gen. W. G.
Prout, Rev. J. T.

Fettows Restenep (18).

Wiiord, C. J. | Jones, D.

Baker, F. _ Middleton, F. E.
Burton, W. J. P. _ Mitcheson, G. A.
Du Pre, F. B. _ Murdock, J. V. B.
Finch, A. L. Penton, E.

Geikie, W. H. C. Quilliam, W. H. A.
Hermitage, H. F. (ivan; Een.
Hilgendorf, F. W. Wilkins, C.
Humble, W. Wilson, C. J.

FreLtows Removen (9).

Buddicom, R. A. | Hampson, B. A.
Butler, C. A. V. pidawieinse We o's
Chenhall, J. W. - Hiorns, A., jun.
Davies, T. H. Lines, E.

Gooch, A. E.

XXll PROCEEDINGS OF THE GEOLOGICAL society. |May 1911,

The following Personages were elected Foreign Correspondents
during the year 1910 :—

Prof. Francois Alphonse Forel, of Lausanne.
Dr. A. E. Térnebohm, of Stockholm.

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 Mr. H. W. Monckton
(also retiring from the Council), retiring from the office of Vice-
President. |

That the thanks of the Society be given to Dr. F, L. Kitchin,
Mr. H. Woods, Mr. H. B. Woodward, and Mr. G. W. Young,

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 Council for the ensuing
Veale

Vol. 67.| , ANNUAL REPORT. Xxill

P OFFICERS AND COUNCIL.—1911.

PRESIDENT.
Prof. William Whitehead Watts, Sc.D., M.Sc., F.R.S.

VICE-PRESIDENTS.

Charles Wilham Andrews, B.A., D.Sc., F.R.S.
Alfred Harker, M.A., F.R.S.

John Edward Marr, Sc.D., F.R.S.

Prof. William Johnson Sollas, LL.D., Sc.D., F.R.S.

SECRETARIES.

Prof. Edmund Johnston Garwood, M.A.
Arthur Smith Woodward, LL.D., F.R.S., F.L.S.

FOREIGN SECRETARY.
Sir Archibald Geikie, K.C.B., D.C.L., LE_)., Sc.D., Pres.R.S.

TREASURER,
Aubrey Strahan, Se.D., F.R.S.

COUNCTL.

Henry A. Allen. | Alfred Harker, M.A., F.R.S.
Tempest Anderson, M.D., D.Sc. Robert Stansfield Herries, M.A.
Charles William Andrews, B.A., | Bedford McNeill, Assoc.R.S.M.

Sc. EAK.S., | John Edward Marr, Se.D., F.R.S.
Henry Howe Arnold-Bemrose, J.P., | George Thurland Prior, M.A., D.Sc.

Sc.D. Prof. Sidney Hugh Reynolds, M.A.
George Barrow. Prof. William Johnson Sollas, LL.D..,
Prof. Thomas George Bonney, Se.D., | Se.D., F.R.S.

CED. F.ER.S. | Aubrey Strahan, Sc.D., F.R:S.
Prof. William S. Boulton, B.Sc. Herbert Henry Thomas, M.A.. B.Sc.
James Vincent Elsden, D.Sc. | Prof.Wiliam Whitehead Watts, Sc.D.,

MSe5, PRS.

John Smith Flett, M.A., D.Sc.
_ Rey. Henry Hoyte Winwood, M.A.

Prof. Edmund J. Garwood, M.A.

pata
Sir Archibald Geikie, K.C.B., D.C.L., | Arthur Smith Woodward, LL.D.,
LL.D., Se.D., Pres.R.8. !

J OEM ars a ved Die

LY PROCEEDINGS OF THE GEOLOGICAL society. [May 1911,

LIST OF
THE FOREIGN MEMBERS

OF THE GEOLOGICAL SOCIETY OF LONDON, 1n 1910,

Date of

Election.

1877. Prof. Eduard Suess, Vienna.

1880. Geheimrath Prof. Ferdinand Zirkel, Leipzig.

1884. Commendatore Prof. Giovanni Capellini, Bologna.
1885. Prof. Jules Gosselet, Lille.

1886. Prof. Gustav Tschermak, Vienna.

1890. Geheimrath Prof. Heinrich Rosenbusch, Heidelberg.
1891. Prof. Charles Barrois, Ezdle.

1893. Prof. Waldemar Christofer Brégeer, Christiania.
1893. M. Auguste Michel-Lévy, Paris.

18938. Prof. 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.).
1895. Dr. Grove Karl Gilbert, Washington, D.C. (U.S.A.).
1896. Prof. Albert Heim, Ziirich.

1897. M. Edouard Dupont, Brussels. (Deceased.)

1897. Dr. Anton Fritsch, Prague.

1897. Dr. Hans Reusch, Christiania.

1898. Geheimrath Prof. Hermann Credner, Lezpzig.

1898. Dr. Charles Doolittle Walcott, Washington, D.C. (U.S.A.).
1899. Prof. Emanuel Kayser, Marburg.

1899. M. Ernest Van den Broeck, Brussels.

1899. Dr. Charles Abiathar White, Washington, D.C. (U.S.A.).
1900. M. Gustave F. Dollfus, Parzs.

1900. Prof. Paul von Groth, Munich.

1900. Dr. Sven Leonhard Tornquist, Lund.

1901. M. Alexander Petrovich Karpinsky, St. Petersburg.
1901. Prof. Alfred Lacroix, Paris.

1903. Prof. Albrecht Penck, Berlin.

1903. Prof. Anton Koch, Budapest.

1904. Prof. Joseph Paxson Iddings, Chicago (U.S.A.).
1904. Prof. Henry Fairfield Osborn, New York (U.S.A.).
1905. Prof. Louis Dollo, Brussels.

1905. Prof. August Rothpletz, Munich.

1906. Prof. Count Hermann zu Solms-Laubach, Strasburg.
1907. Hofrath Dr. Emil Ernst August Tietze, Vienna.
1907. Commendatore Prof. Arturo Issel, Genoa.

1908. Prof. Bundjiré Koto, Tokyo.

1908. Dr. Feodor Cernysev, St. Petersburg.

1909. Prof. Johan H. L. Vogt, Christiania.

1909. Prof. René Zeiller, Paris.

Vol. 67.] ANNUAL REPORT. XXV

LIST OF
THE FOREIGN CORRESPONDENTS

OF THE GEOLOGICAL SOCIETY OF LONDON, rn 1910.

Date of
Election.

1874. Prof. Igino Cocchi, Florence.

1879. Dr. H. Emile Sauvage, Boulogne-sur-Mer.

1889. Dr. Rogier Diederik Marius Verbeek, The Hague.

1890. Geheimer Bergrath Prof. Adolph von Koenen, Gottingen.
1892. Prof. Johann Lehmann, Kvel.

1893. Prof. Aléxis P. Pavlow, Moscow.

1895. M. Ed. Rigaux, Boulogne-sur-Mer.

1894, Dr. Francisco P. Moreno, Za Plata.

1895. Prof. Constantin de Kroustchoff, St. Petersburg.

1896. Prof. Johannes Walther, Halle an der Saale.

1897. M. Emmanuel de Margerie, Paris.
1898. Dr. Marcellin Boule, Paris.

1898. Dr. W. H. Dall, Washington, D.C. (U.S.A.).

1899. Dr. Gerhard Holm, Stockholm.

1899. Prof. Theodor Liebisch, Gottingen.

1899. Prof. Franz Loewinson-Lessing, St. Petersburg.

1899. M. Michel F. Mourlon, Brussels.

1899. Prof. Gregorio Stefanescu, Bucarest. (Deceased.)

1900. Prof. Ernst Koken, Tiibingen.

1900. Prof. Federico Sacco, Turi.

1901. Prof. Friedrich Johann Becke, Vienna.

1902. Prof. Thomas Chrowder Chamberlin, Chicago, Ill. (U.S.A.).
1902. Dr. Thorvaldr Thoroddsen, Copenhagen.

1902. Prof. Samuel Wendell Williston, Chicago, Ill. (U.S.A.).
1904. Dr. William Bullock Clark, Bango CU_S.A3).

1904. Dr. Erich Dagobert von ire aieial Char lottenbur, ".
1904. Prof. Giuseppe de Lorenzo, Naples.

1904. The Hon. Frank Springer, Burlington, Iowa (U.S.A.).
1904. Dr. Henry S. Washington, Locust, N.J. (U.S.A.).

1906. Prof. John M. Clarke, Albany, N.Y. (U.S.A.),

1906. Prof. William Morris Davis, Cambridge, Mass. (U. S.A. Me
1906. Dr. Jakob Johannes Sederholm, Helsingfor's.

1907. Prof. Baron Gerard Jakob de Geer, Stockholm.

1907. Prof. Armin Baltzer, Berne.

1908. Prof. Hans Schardt, Veytauxr, near Montreux.

1909. Dr. Daniel de Cortazar, Madrid.

1909. Prof. Maurice Lugeon, Lausanne.

1909. Prof. Ralph 8. Tarr, Ithaca, N.Y. (U.S.A.).

1910. Prof. Frangois Alphonse Forel. Zausanne.

1910. Dr. A. E. Térnebohm. Strengnés.

VOL. LXVII. C

XXV1

PROCEEDINGS OF THE GEOLOGICAL SOCIETY.

[May 1911,

AWARDS OF THE WOLLASTON MEDAL

UNDER THE CONDITIONS OF THE ‘ DONATION FUND’

ESTABLISHED BY

WILLIAM HYDE WOLLASTON, M.D., F.R.S., F.G.S., ere.

‘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.’

Lak.
1835,
1836.
183%
1838.
1839.
1840.

1841.
1842,
1845.
1844.
1845.
1846.
1847.
1848.
1849.
1850,
1851,
1852,

1853.

1854,
1855.
1856,
1857.

1858.

1859,
1860.
1861.
1862.
1863.
1864,
1865.
1866,
1867.
1868,
1869.
1870.
1871.
1872,

Mr. William Smith.
Dr. Gideon A. Mantell.
M. Louis Agassiz.
Capt. T. P. Cautley.
Dr. Hugh Falconer.
Sir Richard Owen.
Prof. C. G. Ehrenberg.
Prof. A. H. Dumont.
M. Adolphe T. Brongniart.
Baron Leopold von Buch.
M. Elie de Beaumont.
M. P. A. Dufrénoy.
The Rev. W. D. Conybeare.
Prof. John Phillips.
Mr. William Lonsdale.
Dr. Ami Boué.

The Very Rev. W. Buckland.

Sir Joseph Prestwich.
Mr. William Hopkins.

The Rey. Prof. A. Sedgwick.

Dr We Patton:

M. le Vicomte A. d’Archiac.

M. I. de Verneuil.
Sir Richard Griffith.
Sir Henry De la Beche.
Sir William Logan.
M. Joachim Barrande.

Herr Hermann von Meyer.

Prof. James Hall.
Mr. Charles Darwin.
My. Searles V. Wood.
Prof. Dr. H. G. Bronn.

Mr. R. A. C. Godwin-Austen.

Prof. Gustav Bischof.
Sir Roderick Murchison.
Dr. Thomas Davidson.
Sir Charles Lyell.

Mr. G. Poulett Scrope.
Prof. Carl F. Naumann.
Dr. Henry C. Sorby.
Prof. G. P. Deshayes.
Sir Andrew Ramsay.
Prof. James D. Dana.

1873.
1874,
1875.
1876.
1877.
1878.
theyieh
1880.
1881.
1882.
1885.

1884.
1885,
1886.
1887.
1888.
1889.
1890.
1891.
1892,
1893.
1894.
1895.
1896.
1897.
1898.
1899.
1900.
1901.
1902.
1905.
1904.
1905.
1906.
1907.
1908.
1909.
IIS DUG,

UGE

Sir P. de M. Grey Egerton.

Prof. Oswald Heer,

Prof. L. G. de Koninek.

Prof. Thomas H. Huxley.

Mr. Robert Mallet. i

Dr. Thomas Wright.

Prof. Bernhard Studer.

Prof. Auguste Daubrée.

Prof. P. Martin Duncan.

Dr. Franz Ritter von Hauer.

Dr. William Thomas
Blanford.

Prof. Albert Jean Gaudry.

Mr, George Busk.

Prof, A. L.O. Des Cloizeaux.

Mr. John Whitaker Hulke.

Mr. Henry B. Medlicott.

Prof.Thomas George Bonney.

Prof. W. C. Williamson.

Prof. John Wesley Judd.

Baron F. von Richthofen.

Prof. NevilStory Maskelyne.

Prof. Karl Alfred von Zittel.

Sir Archibald Geikie.

Prof. Eduard Suess.

Mr. Wilfrid H. Hudleston.

Prof. Ferdinand Zirkel.

Prof. Charles Lapworth.

Dr. Grove Karl Gilbert.

Prof. Charles Barrois.

Dr. Friedrich Schmidt.

Prof. Heinrich Rosenbusch.

Prof. Albert Heim.

Dr. J. J. Harris Teall.

Dr. Henry Woodward.

Prof. William J. Sollas.

Prof. Paul von Groth.

Mr. Horace B. Woodward.

Prof. William Berryman
Scott.

Prof. Waldemar Christofer
Brogger,

Vol.'67.]

1831.
1833.
1834.
1855.
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.
1865.
1864.
1865.
1866.
1867.
1868.
1869.
1870.

ANNUAL REPORT.

AWARDS
OF THE
BALANCE OF THE PROCEEDS OF THE WOLLASTON

‘DONATION FUND.’

Mr. William Smith.
Mr. William Lonsdale.
M. Louis Agassiz.

Dr. Gideon 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.

M. Alcide d’Orbigny.
My. William Lonsdale.
Prof. John Morris.

M. Joachim Barrande.
Prof. John Morris.

Prof. L. G. de Koninek.
Dr. Samuel P. Woodward.
Dr. G. Sandberger.

Dr. F. Sandberger.
Prof. G. P. Deshayes.
Dr. Samuel P. Woodward.
Prof. James Hall.

Mr. Charles Peach.

Prof. T. Rupert Jones.
ae W. K. Parker.
Prof. Auguste Daubrée.
Prof. Oswald Heer.
Prof. Ferdinand Senft.
Prof. G. P. Deshayes.
Mr. J. W. Salter.

Dr. Henry Woodward.
My. W. H. Baily.

M. J. Bosquet.

Dr. William Carruthers.
M. Marie Rouault.

1871.

1872.

1873.
1874.
1875.
1876,

| 1877.

1878.
1879.
1880.
1881.
1882.
1885,
1884,

| 1885.
hs of Good Hope Fossils. |

1886,
1887,
1888,
1889.
1890.
1891.
1892.
1895.
1894.
1895,
1896,
1897.
1898.
1899.
1900.
1901.

1902.

1903.

| 1904.

1905.
1906.

| 1907.
| 1908.
1909.
1910.

TOL,

XXxvl

Mr. Robert Etheridge.

Dr. James Croll.

Prof. John Wesley Judd.
Dr. Henri Nyst.

Prof. Louis C. Miall.

Prof. Giuseppe Seguenza.
Mr. Robert Etheridge, jun.
Prof. William J. Sollas.
Mr. Samuel Allport.

Mr. Thomas Davies.

Dr. Ramsay H. Traquair.
Dr. George Jennings Hinde.
Prof. John Milne.

Mr. Edwin Tulley Newton.
Dr. Charles Callaway.

Mr, J. Starkie Gardner.

Dr. Benjamin Neeve Peach.
Dr. John Horne.

Dr. A. Smith Woodward.
Mr, William A. I. Ussher.
Mr. Richard Lydekkev.

Mr. Orville Adelbert Derby.
Mr. John George Goodchild.
Dr. Aubrey Strahan.

Prof. William W. Watts.
Mr. Alfred Harker.

Dr. Francis Arthur Bather.
Prof. Edmund J. Garwood.
Prof, John B. Harrison.

Dr. George Thurland Prior.
Mr. Arthur Walton Rowe.
Mr. Leonard James Spencer.
My, L. L. Belinfante.

Miss Ethel M. R. Wood.
Dr. H. H. Arnold-Bemrose.
Dr. Finlay Lorimer Kitchin.
Dr. Arthur Vaughan.

Mr. Herbert Henry Thomas.
Mr. Arthur J.C. Molyneux.
Mr. Edward B. Bailey.
Prof. Owen Thomas Jones.

e2

XXVl

u

PROCEEDINGS OF THE GEOLOGICAL SOCIETY.

| May rort,

AWARDS OF THE MURCHISON MEDAL

UNDER THE CONDITIONS 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 in 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. Mr. William Davies.

1874.
1875.

1876

Dr. J. J. Bigsby.
Mr. W. J: Henwood.
. Mr. Alfred R. C. Selwyn.

1877. The Rev. W. B. Clarke.
1878. Prof. Hanns Bruno Geinitz.

1879.

Sir Frederick M‘Coy.

1880. Mr. Robert Etheridge.

1881.
1882.
1883.
1884,
1885.
1886.
1887.
1888.

Sir Archibald Geikie.

Prof. Jules Gosselet.

Prof. H. R. Goeppert.

Dr. Henry Woodward.

Dr. Ferdinand von Reemer.
Mr. William Whitaker.
The Rev. Peter B. Brodie.
Prof. J. S. Newberry.

1889. Prof. James Geikie.

1890.
1891.
1892.
1893.

Prof. Edward Hull.

Prof. A. H. Green.
The Rev. Osmond Fisher.

Prof. Waldemar C. Brogger.

1894,
| 1895.
| 1896.
1897.
- 1898.

1899.

1900.
1901.
1902.
1903.
1904.
1905.
1906.
eto
1908.
1909.
1910.

Its

Mr. William T. Aveline.

Prof. Gustaf Lindstrom.

Mr. T. Mellard Reade.

Mr. Horace B. Woodward.

Mr. Thomas F. Jamieson.
Dr. Benjamin Neeve Peach.

ie John Horne.

Baron A. E. Nordenskiold.
Mr. A. J. Jukes-Browne.
Mr. Frederic W. Harmer.
Dr. Charles Callaway.

Prof. George A. Lehbour.

Mr. Edward John Dunn.

Mr. Charles T. Clough.

Mr. Alfred Harker.

Prof. Albert Charles Seward.

Prof. Grenville A. J. Cole.

Prof. Arthur Philemon

Coleman.
Mr. Richard Hill Tiddeman.

Vol. 67. | ANNUAL REPORT. Exix

AWARDS
OF THE

BALANCE OF THE PROCEEDS OF THE %
‘MURCHISON GEOLOGICAL FUND.’

1873. Prof. Oswald Heer. | 1892. Mr. Beeby Thompson.

1874. Mr. Alfred Bell. | 1898. Mr. Griffith John Williams.
Prof. Ralph Tate. _ 1894, Mr. George Barrow.

1875. Prof. H. Govier Seeley. 1895. Prof. Albert CharlesSeward.

1876. Dr. James Croll. 1896. Mr. Philip Lake.

1877. The Rev. John F. Blake. 1897. Mr. Sydney S. Buckman.

1878. Prof. Charles Lapworth. | 1898. Miss Jane Donald.

1879. Mr. James Walker Kirkby. | 1899. Mr. James Bennie.

1880. Mr. Robert Etheridge. 1900. Mr. A. Vaughan Jennings.

1881. Mr. Frank Rutley. 1901. Mr. Thomas 8. Hall.

1882. Prof. Thomas Rupert Jones. | 1902. Sir Thomas H. Holland.

1883. Dr. John Young. _ 1903. Mrs. Elizabeth Gray.

1884, Mr. Martin Simpson. _ 1904. Dr. Arthur Hutchinson.

1885. Mr. Horace B. Woodward. 1905. Prof. Herbert L. Bowman.

1886. Mr. Clement Reid. _ 1906. Dr. Herbert Lapworth.

1887. Dr. Robert Kidston. 1907. Dr. Felix Oswald.

1888. Mr. Edward Wilson. 1908. Miss Ethel Gertrude Skeat.

1889. Prof. Grenville A. J. Cole. 1909. Dr. James Vincent Elsden.
1890. Mr. Edward B. Wethered. 1910. Mr. John Walker Stather.
1891. The Rev. Richard Baron. —_ 1911. Mr. Edgar Sterling Cobbold.

XXX PROCEEDINGS OF THE GEOLOGICAL soclEry. [May 1911,

AWARDS OF THE LYELL MEDAL

UNDER THE CONDITIONS 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 cast in bronze and 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.’

There is a further provision for suspending the award for one year, and in
such case for the awarding of a Medal to ‘ each of two persons who have been
jointly engaged in the same exploration in the same country, or perhaps on
allied subjects in different countries, the proportion of interest always not being
less to each Medal than one third of the annual interest.’

1895. The Rev. John F. Blake.
1896. Dr. Arthur 8S. Woodward.
1897. Dr. George Jennings Hinde.
1898. Prof. Wilhelm Waagen.
1899. Lt.-Gen. C. A. MeMahon.
1900. Dr. John Edward Marr.

1876. Prof. John Morris.
1877. Sir James Hector.
1878. Mr. George Busk.

1879. Prof. Edmond Hébert.
1880. Sir John Evans.

1881. Sir J. William Dawson.

1882. Dr. J. Lycett.

1901. Dr. Ramsay H. Traquair.

1883. Dr. W. B. Carpenter. 1902 ae Anton Fritsch.

1884. Dr. Joseph Leidy. ‘UMr. Richard Lydekker.
1885. Prof. H. Govier Seeley. 1903. My. Frederick W. Rudler.
1886. Mr. William Pengelly. 1904. Prof. Alfred G. Nathorst.
1887. Mr. Samuel Allport. 1905. Dr. Hans Reusch.

1888. Prof. Henry A. Nicholson. 1906. Prof. Frank Dawson Adams.
1889. Prof. W. Boyd Dawkins. 1907. Dr. Joseph F’. Whiteaves.
1890. Prof. Thomas Rupert Jones. | 1908. Mr. Richard Dixon Oldham.
1891. Prof. T. McKenny Hughes. | 1909. Prof. Perey Fry Kendall.
1892. Mr. George H. Morton. 1910. Dr. Arthur Vaughan.

1893. Mr. Edwin Tulley Newton. 1911 Le Francis Arthur Bather.
1894. Prof. John Milne. ' |Dr. Arthur Walton Rowe.

Vol. 67.|

1876.
1877.
1878.
1879.
1879.
1880.
1881.
1gsl.
1882.
1882.
1883.
1883.
1884,
1885.
1886.
1887.
1888.
1888.
1889.
1890.
1891.
1891.
1892.
1892.
1893.
1893.
1894.
1895.
1895.

ANNUAL REPORY.

AWARDS

OF THE

BALANCE OF THE PROCEEDS OF THE
‘LYELL GEOLOGICAL FUND,’

Prof. John Morris.

Mr. William Pengelly.
Prof. Wilhelm Waagen.
Prof. Henry A. Nicholson.
Dr. Henry Woodward.
Prof. F. A. von Quenstedt.
Prof. Anton Fritsch.

My. G. R. Vine.

The Rey. Norman Glass.
Prof. Charles Lapworth.
Mr. P. H. Carpenter.

M. Ed. Rigaux. -

Prof. Charles Lapworth.

My. Alfred J. Jukes-Browne. |

Mr. David Mackintosh.
The Rey. Osmond Fisher.
Dr. Arthur H. Foord.

Mr. Thomas Roberts.

Dr. Louis Dollo.

Mr. Charles D. Sherborn.
Dr. C. I. Forsyth Major.
Mr. George W. Lamplugh.
Prof. John Walter Gregory.
Mr. Edwin A. Walford.
Miss Catherine A. Raisin.
Mr. Alfred N. Leeds.

Mr. William Hill.

Prof. Percy Fry Kendall.
Mr. Benjamin Harrison.

1896.
1896.
1897.
1897.
1898.
1898.
1899.
1899.
1900.

| 1901.
| 1901.

1902.
1903.
1905.
1904.

1904.

1905.

| 1905.

1906.
1906.
1907.
LOO re
1908.
1908.
1909.
1909.
1910.
1910.
1911.

Dr. William F. Hume.

Dr. Charles W. Andrews.
Mr. W. J. Lewis Abbott.
Mr. Joseph Lomas.

Mr. William H. Shrubsole.
Myr. Henry Woods.

Mr. Frederick Chapman.
Mr. John Ward.

Miss Gertrude L. Elles.

Dr. John William Evans.
Mr. Alexander McHenry.
Dr. Wheelton Hind.

Mr. Sydney S. Buckman.
Mr. George Edward Dibley.
Dr. Charles Alfred Matley.
Prof. Sidney Hugh Reynolds.
Mr. EK. A. Newell Arber.
Dr. Walcot Gibson.

Mr. William G. Fearnsides.
Mr. Richard H. Solly.

Mr. T. Crosbee Cantvrill.
Mr. Thomas Sheppard. |
Dr. Thomas Franklin Sibly. *
Mr. H. J. Osborne White.
Mr. H. Brantwood Maufe.
Mr. Robert G. Carruthers.
Mr, F. R. Cowper Reed.
Dr. Robert Broom.

Dr. Charles Gilbert Cullis,

i
i
}

5.6.6.0 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May-1911,

AWARDS OF THE BIGSBY MEDAL,

FOUNDED BY THE LATE

Dr. J. J. BIGSBY, PRS, EGS.

To be awarded biennially ‘as an acknowledgment 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. Prof. Othniel Charles Marsh. | 1897, Mr. Clement Reid.

1879. Prof. Edward Drinker Cope. | 1899, Prof. T. W. perc!
1881. Prof. Charles Barrois. David.

1883. Dr. Henry Hicks. | 1901. Mr. George W. Lamplugh.
1885. Prof. Alphonse Renard. 1903. Dr. Henry M. Ami.

1887. Prof. Charles Lapworth. 1905. Prof. John Walter Gres
1889. Dr. J. J. Harris Teall. | 1907. Dr. Arthur W. Rogers.
1891. Dr. George Mercer Dawson.) 1909. Dr. John Smith Flett,
1893. Prof. William J. Sollas. | 1911. Prof. Othenio Abel.

895. Dr. Charles D. Walcott.

AWARDS OF THE PRESTWICH MEDAL,

ESTABLISHED UNDER THE WILL OF THE LATE

SIR JOSEPH PRESTWICH, F.R.S., F.G-S.

‘To apply the accumulated annual proceeds ... at the end of every three years, in
providing a Gold Medal of the value of Twenty Pounds, which, with the
remainder of the proceeds, is to be awarded ...to the person or persons, either
male or female, and either resident in England or abroad, who shall have done well
for the advancement of the science of Geology ; or, from time to time to accumulate
the annual proceeds for a period not exceeding six years, and apply the said
accumulated annual proceeds to some object of special research bearing on
Stratigraphical or Physical Geology, to be carried out by one single individual or
by a Committee; or, failing these objects, to accumulate the annual proceeds for
either three or six years, and devote such proceeds to such special purposes as
may be decided.’

1903. John Lubbock, Baron Av ebury. ‘
1906. Mr. William Whitaker.
1909. Lady Evans.

Vol. 67.] ANNUAL REPORT. 0.0.50)

AWARDS OF THE PROCEEDS OF THE BARLOW-
JAMESON FUND,

ESTABLISHED UNDER THE WILL OF THE LATE
Dr. H. C. BARLOW, F.G.S.

‘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. Purchase of Microscope. | 1896. Mr. John Storrie.

1881. Purchase of Microscope- | 1898. Mr. Edward Greenly.
Lamps. 1900. Mr. George C. Crick.

1882, Baron C, von Ettingshausen. | 1900. Dr. Theodore I’. Groom.

1884. Dr. James Croll. 1902. Mr. William M. Hutchings.

1884, Prof. Leo Lesquereux. 1904. My. Hugh John Ll. Beadnell.

1886. Dr. H. J. Johnston-Layvis. 1906. Mr. Henry C. Beasley.

1888. Museum.

1908. Contribution to the Fund

1890. Mr. W. Jerome Harrison. : for securing the Preser-

1892. Prof. Charles Mayer-Eymar. | vation of the Sarsen-

1893. Purchase of Scientific In- Stones on Marlborough
struments for Capt. F. F. Downs, known as ‘The
Younghusband. Grey Wethers.’

1894, Dr. Charles Davison. 1911. Mr. John Frederick Norman

1896. Mr. Joseph Wright. | Green,

AWARDS OF THE PROCEEDS OF THE
‘DANIEL PIDGEON FUND,

FOUNDED BY MRS. PIDGEON, IN ACCORDANCE WITH THE
WILL OF THE LATE

DANIEL PIDGEON, F.G.S.

‘An annual grant derivable from the interest on the Fund, to be used at the
discretion of the Council, in whatever way may in their opinion best promote
Geological Original Research, their Grantees being in all cases not more than
twenty-eight years of age.’

1903. Prof. Ernest Willington | 1908. Mr. James A. Douglas.

Skeats. 1909. Dr. Alexander Moncrieff
1904. Mr. Linsdall Richardson. Finlayson.
1905. Mr. Thomas Vipond Barker. | 1910. Mr. Robert Boyle.
1906. Miss Helen Drew. 1911. My. Tressilian Charles

1907. Miss Ida L. Slater. | Nicholas.

2. O-O1Y PROCEEDINGS OF THE GEOLOGICAL sociery. | May 1911,

Estimates for

INCOME EXPECTED.

Compositions: ji-.)0s Saniemy eke exe oe biel AS oth GRRE ae anne 140° 0 710
Arrears of Admission=Hees <3... 6. oc. a2 sateen toll Apter (0)
Admyssion= Bees: WOM cee he.) Sa en ae 200 12 0
————— 28210 90
Arrears of Annual Contributions ............ 150 0G
Annual Contributions, 1911, from Resident and
Non-Resident Hellows to. se des f. ic eee as 1900 0 0
Annual Contributions in advance ............ 1 Oe
h a 2105 0 O
Sale of the Quarterly Journal, including Lone- |
TILA Se NIGCOUM tera, Ae cok nekwrk ie! ete gos @sbeatece Go Mica eaNe 16000
Salerotother Binblicaitong ic foc. scale eyes Lae eee LO! 10%0
Mnscellameous WWecenptss. smh) 2 <.u 2 Wao eithil ts enone ; 6 O50
Interest on Deposit=Necouml) 06. 1.)./2% wel. + ors sa | eee , 10” 0 46

Dividends on £2500 India 3 per cent. Stock .. 75 O O

Dividends on £300 London, Brighton, & South
Coast Railway 5 per cent. Consolidated Pre-

FEPOMES LOCK sae tera cake tito isig oes a eras Te OO)
Dividends on £2250 London & North-Western

Railway 4 per cent. Preference Stock ...... SO) 0)
Dividends on £2800 London & South-Western

Railway 4 per cent. Preference Stocx ...... je, (0) © (0)
Dividends on £2072 Midland Railway 23 per

cent, Perpetual Preference Stock 1% .).4).).).< Diel6.40

Dividends on £267 6s.7d. Natal Sper cent. Stock. 8 O O

— 35116 0

£3065 6 O

[Novn.—The accumulated interest on the Sorby and Hudleston Bequests,
which will amount on December 31st, 1911, to £151 16s. 8d., is not
included in the above estimate of Income expected. |

ta! ee ee ee ii i lS eR ll a al i

AUBREY STRAHAN, Treasurer.
January 27th, 1911.

Vol. 67.| FINANCIAL REPORT. XNXV
the Year 1911.
EXPENDITURE ESTIMATED.
£625 a yee te
House-lxpenditure :
7 GIERAIOS Seer Pig SAA ORS ee mes cpp CEE ET 15 0
Fire-Insurance and other Insurance ............ IG 20ra0
Electric Lighting and Maintenance ............ 50° 0.40
PG ie ane ARN orn Sein. nteia placa rinaitic ecisa ae Saisie Teale olre FV a | Sone
PENS gee ct neice ear ain Gira iivle nese pate daindorwd de 39 0 O
Hurniture and Repairs... .s1-0<2cous-vooeee 50 0 O
House-Repairs and Maintenance ............... 40 0 O
AARENONAI A LOSTNNTA ol waco vaatinneaqades denewegades ss 25 °0°".0
Wiearat MEPGhIn iso. 26. seecek ot cece ess sek cede de se siees lo 0-0
Washing and Sundry Txpenses .................. 30 0 O
282 15 0
Salaries and Wages, etc. :
PUBRUSUINE- NE CECUALY | voces sions. ons cnceencyacadneces VT Oe nO
~ half Premium Life-Insurance... 10 15 O
PRS ESe eM PMUTATIAW hon oes ieee tose «ad ce eies><inedepici 15034 O40
PMSSIN EMER Onl OT Keele shah Soe sans.d conden aeniecs yeeccs 150.0. 0
Junior Assistant ........... Oe PERE OIE AO £0
House-Porter and Upper Housemaid ......... 94) 020
Wnt EN OVSCINAUN fon coc. in =o e's ainse cc ceeccnss anf 49 18 0
Charwoman and Occasional Assistance......... l4 0 O
PRPC OUPANDS MECH. oi. vin taddereacranna-vectoneesses LO; 10.0
SOT yO)
Office-Expenditure :
PH ONO ip eas feat Cuislspaicteeadin«Sndecnaswcten 30 0 0
Wscelianeous Printing, ete. \y..c22.<c<esccs<s<e+e 60 0 O
Postages and Sundry Hxpenses .................. fd. D510
165 0 @O
mitre (POO AMO PAINS) oie oes aoe ea tis iace #'e 26 me rms 250 0 0
Library Catalogue :
(CHING Sho a ol er BE ae Rae 20, 0-0
IAG as eon. nrc sk oecereshess the wees ses ae 50 O O
‘ 720 076
Publications:
Quarterly Journal, including Commission on
ALOR tac vs sae tess nk nen weaWis sem. se'ascentubeaeres 1000 0 O
Postage on Journal, Addressing,.ete............. 100 O O
Record of Geological Literature ............... 150 0 90
Abstracts of Proceedings, including Postage... 105 O O
net of Hewows)« (5c. c0c..cadaaerteoateenacttly ae eus 40 0 O
139d. 0» 0
3063 18 0
Kstimated excess of Income over Expenditure .. L/S.0€

£3065 6 O

XXXV1 PROCEEDINGS OF THE GEOLOGICAL society. [May rgort,

Income and Expenditure duriny the

RECEIPTS.
. £8: dy Ss eee
To Balance in the hands of the Bankers at

January. Lists MOO een Sai cid cae 167) lovee
,, Balance in the hands of the Clerk at .
danuary ahetewonOs) 6/5. ss 2 eee A iets
——_———— 178 18 2
3° Compositions ig & ris eh.c.s a's taunts Caters ee AE 10<- Or 20
,, Admission-Fees:
PNET HIS so cae oSaeeunh contest sere meee 132) 65-0
COMBE jn cesuspacuasecneemeeteser 214 4 O
——— 346 10 0
», Arrears of Annual Contributions .... 159 14 0
,» Annual Contributions for 1910 :—
Resident Fellows .................. 1906 14 0
Non-Resident Fellows ............ 4 14 6
,, Annual Contributions in advance .... 84 0 O
———— 2155 2 6
., Publications:
Sale of Quarterly Journal : *
» Vols. 1 to Ixv (less Commission
POURS OGL): sees Rts paces ee Sy ey ae
» Vol. lxvi(less Commission £2 18s.6d.) 45 14 6
2033) lias
Other se ubligatione::. cess swcacese eee Sie dae
33 Miscellaneous Recerptis > iyo asieiea e eseeee Ih cee
5, Repayment of Income-Tax (1 year). .a)s 55 eae 21) Vigel
~eunterest on) Deposit-Accoumt, a .ce +) see re ee 12 16558
yn eracy =
Robert ammalis eee wean sannscnvancees sces so eats meee 100 0 @
., Dividends (less Income-Tzx) :-—
£2500 "Indias per cent. Stock /..2.5.2..--.2225 [012 4
£300 London, Brighton, & South Coast Rail-
way 5 per cent. Consolidated Prefer-
ENEOISLORK Reco s.ut 1a eon ety ommemrecee ss 14. 2.6
£2250 London & North-Western Railway
4 per cent. Preference Stock ......... 8415 0
£2800 London & South-Western Railway
4 per cent. Preference Stock <....-..- 105s coe
£2072 Midland Railway 23 per cent. Per-
petual Preference Stock ............... 48 15 6
£267 si id. Natal 3 per'cent. Stock > <<_...--. 7 WO
—_——_———. 831 5 8
* A further sum is due from Messrs. Longmans ————EE
& Co. for Journal-Sales ............ £8) 16 40 £2499 spree
Special Funds.
Hudleston Bequest. Sorby Bequest.
£1000 Canada 34 °/, Stock. £1000 Canada 34 °/, Stock.
Eas. eG: 2st ee
lo. Dividends “ee aos 321952. To Dividends 4.2. ae 32 19 2

By Balance tonext Acct.. 3219 2 By Balance tonext Acct.. 3219 2

my
. M4

Wall-67 | FINANCIAL REPORT. XXXVll
Year ended December 31st, 1910.
PAYMENTS.
By House-Expenditure: yee) a. ca, “ae
LE AT2h iene Bas Chee ek Se a eee a Ee 15 0
Fire-Insurance and other Insurance ......... 16 3 5
Electric Lighting and Maintenance ......... 54:16 5
Ces eg deren Pe an was « wanenulbaeed voces 155 2010
PLease erie eR ncn kau any epaphonezcness 30 11 0
Burniture and Nepales. ......55 fo-.cds veces oceans 60 15 9
House-Repairs and Maintenance............... 38 8 10
ATMA OLGATIUN: fave wciecien scdasesecaactssaicecncee 2718 4
SRE ALCO LINIDR pw aviecscaccacaaSdncechatacsacl ss 1410 9
Washing and Sundry Expenses ............... a2 13 2
284 15 7
», salaries and Wages:
SAR SISUANIG-SOCLCLANY sciescncacesadesdilecciecscecs SLO 0
, half Premium Life-Insurance... 1015 0O
Sst ta MA MANNA! ecw sne Sn eicasskerdwae canines 058 150 0 O
PRIME OL OP iga a ccic a cive inde accee <P ecasnanvawesion 150.0 0
MNMOT PA SGISKA TU sole2ce ss cece sjednnsovecdscuce oa OO
House-Porter and Upper Housemaid ...... 94 1 6
Minder OUSeMaAIGs 25.0..008.c<cecectewssecesosae 49 18 O
Charwoman and Occasional Assistance ...... 3 27,0
AC COMMNTAMES, WEOi s cancessccsaaeccecesecectt coves 10 10 O
—— 888 1 6
,, Office-Expenditure :
SUTIILCUVEEAYS SMe ate ale ee em ae a LORE
Miscollancous Printing! .....05..020..-.sc00se08 68 8 ll
Postages and Sundry Expenses ............... 66 19 10
——— 154 9 8
eo ihipragy (books:and Binding) <.........0-2 2% Zag Ly ak
,, Library-Catalogue :
CHAREIES 52, ck SS an ae a ae Ae 24 5 0
CIOTS CS ESE ee a0. O20
——' | 74.5 (0
,, Publications:
Quarterly Journal, Vol. Ixvi, Paper, Print-
ane amr LUN ISHALTONS <6 isc cen ncnseannene sas 898 18 8
Postage on Journal, Addressing, etc. ...... TOES 7
Record of Geological Literature ............ 162 12 0O
Abstracts, including Postage ~ ............... LOD Oe a
eet eM OMS et oh. Aacsin nnd swe r eared ve cleat 62 16 6
——§— 1526 12 4
,, Balance in the hands of the Bankers at
Wecemberra lst, LOLOe sok oes ee, 493 8 2
,, Balance in the hands of the Clerk at
Mecember ost. Wl OQ seo cee: 2 LTO

We have compared this Statement with
the Books and Accounts presented to us,
and find them to agree.

GEORGE W. YOUNG

—- 452 19

bo

£3438 15 4

| TS

C. GILBERT CULLIS | Auditors.
AUBREY STRAHAN, Treasurer.

January 27th, 1911.

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ENS TO

Pt tee

Statement of Trust-Munds : December 81st, 1910,
‘Wortaston Donation lunp.’ Trusr Accounn.

Reenrers, ow PAYMENT
To Balanco at the Bankers’ at January Ist, 1910........ pop? ti 82 By Cost of Medal Ravonee!
» Dividends (less Tneome-Tax) on the Mund invested in | ., Award from the Balnnes of the und,

£1078 Hampshire County 8 per cent. Stock ...... 80 6 2! », Balance at the Bankers’ at December Slat 1910
at, 1f

» Repayment of Income-Tax (1 year) .....ceeeeeeeees = 17 8

£64 5 0
“Murcuison Gronoaican Funn. Trust Accounr,

Rreriprs, CE et 5 PAYMENTS
ote 20 18 6) By Award to the Medallist

£1884 London & North-Western Railway 38 per cent,

IEAHAIOSLICUK | “Soro g db cin ado dor COLO Gann 57:15 8
» Repayment of Income-ax (1 year) .........0e 0c eee 2 6 0
£60) 17 2

‘LyeLt Gronoaican Funp.’ Trusr Accounn,

VECRIPTS Se. Grane,

. ‘ C s. d, PAYMENTS
To Palnues at ve Bankers’ at January Ist, 1910...... 53 7 0} By Award to the Medalli rae
+; Dividends (less Income-Tax) on the Fund invested in , First A i ISK ate Rta See

i ( ‘ 01 8 _ st Award from the Balance of the J

n £2010 Is, Od. Metropolitan 34 per cent. Stock .... 66 5 0) ,, Second Award from bial es wd 1

> . n Tax , . B) ? nN 3 oe

+» Repayment of Income-Tax (1 year) ................ 3.19 1) ,, Balance at the Bankers’ at December 31st 1910

£123) 17) 1

‘ Bartow-Jameson Funp.’ Trust Account.
Reerirrs. £

: hah PAYMEN'
Yo Balance at the Bankers’ at January Ist, 1910 41 7 y Sera
aa f a st, 1910..,..... ‘ 0} By Bale at the Bankers’ eee
», Dividends (less Income-Tax) on the Fund invested in ‘ sae ede Suen ai ReaD cenit eee
4 6
5 9
i738

ST

nie LOS
usners 21 11

Ton WZ OF iLO,

£64 5
co Ep,
10 10
29 65
VAL

£60 17 2

: Rrerirrs. ca B PASIIENTS.- = =
Vo Balance at the Bankers’ at January Ist, 1910 ........ 3 5 8] By Balance at the Bankers’ at December 31st, 1910 @) At fs)
», Dividends (less Income-Tax) on the Fund invested in
£210 Cardiff.'3 percent, Stock .............+...- 518 8
3, Repayment of Income-Tax (1 year) ..........00- 00. 7 4
£43) Tht. tal SO Liles:
‘Grotocican Revier Punn.’ Trusr Account.
LECEIPTS. 18 Gb PAYMENTS. oie Ch
To Balance at the Bankers’ at January Ist,1910........ vo 2 | By Grants ...... sooLdHesDO0G0G0 dandiponanoadondons 220
,, Dividends (less Income-Tax) on the Fund inyested in ., Balance at the Bankers’ at December 31st, 1910 .. 35 6 10
£139 3s. 7d. India 3 per cent. Stock..........-... 318 8
,, Repayment of Income-Tax (1 year) ...........-.. 47
£37 8 10 £37 8 10
©Prespwicu Trust Funp.’ Trust Account’.
Recripts. £2 Go| PAYMENTS. a5 Gy th
Yo Balance at the Bankers’ at January Ist, 1910........ 44 7 7) By Balance at the Bankers’ at December 31st, 1910 65 6 9
;, Dividends (less Income-Tax) on the Fund invested in
£700 India) 3 percent: Stock ............0.-05. 1915 8
», Repayment of Income-Tax (1 year) ............+- i 8)
£65 6 9 £65 6 9
‘Daniet Pipcron Funny. Trust Account.
RECEIPTS, £ os. a. PAYMENTS. £sd
Yo Balance at the Bankers’ at January Ist, 1910 ...... Is) 133} @) 4] IB Awl o560 00000 2mbD.Jo0oo0 CnHdODOuUNDGOOOS noogs al) GO dl
,, Dividends (less Income-T'ax) on the Fund inyested in » Balance at the Bankers’ at December 31st, 1910 .... 16 3 5
£1019 1s. 2d. Bristol Corporation 3 per cent. Stock. 28 15 10
;, Repayment of Income-Tax (l year) |............. 115 6
£46 9 9 "£16 9 9
We have compared this Statement with the Books and Accounts presented to us, and find them to agree.
AUBREY STRAHAN, Treasurer, - GEORGI W. YOUNG, Wseies
C. GILBERT CULLIS' } MOR,

January 27th, 1911,
——= rrr eee eee ee ee ee ee ee a

oa PROCEEDINGS OF THE GEOLOGICAL SOCIETY.

[May 1911,

Statement relating to the Society’s Property :

December 31st, 1910.

Balance in the Bankers’ hands, December 31st,
1910:
On Current Account 493.8 2

eee e rte ese eee e sence ester easece

Balance in the Clerk’s hands, December 3lst,1910 29 11 O
Due from Messrs. Longmans & Co., on account
of Quarterly Journal, Vol. LXVI, ete. ........ a6) (G00
Arrears of Admission-Fees#..... 5... .0ntale os ues 100 16 0
Arrears of Annual Contributions .............. 235 6 O
Funded Property, at cost price :—
£2000 India’s per cent. Stock 200. ........ 2628 1978
£300 London, Brighton, & South Coast Rail-
way 5 per cent. Consolidated Preference
HOLS LG nae NR Aah ore RA Hea a EEA Sc. 502 15 3
£2250 London & North-Western Railway
4 per cent. Preference Stock . 2... 2.2... 2898 10 6
£2800 London & South-Western Railway
4 per cent. Preference Stock ............ 3607 = 7G
£2072 Midland Railway 23 per cent. Per-
petual Wreference Stocks . 770) ./sactemiee era. 1850 19 6
L268 Cssmda Natal io percent «Stock «scare 250" O.70
£2000 Canadayas per cent. Stock .. 0.25550. 198250)

——_—

SE WS a Mb
AD? lOve
394 8 O

S847 ae

13,716 2 9

[N.B.—The above amount does not include the value of the Collections, Library,

Furniture, and Stock of unsold Publications.

The value of the Funded Property

of the Society at the prices ruling at the close of business on December 31st, 1910,

amounted to £11,703 16s. 9d. |

AUBREY STRAHAN, Treasurer.
January 27th, 1911.

Vol. 67.1] ANNIVERSARY MEETING-——-WOLLASTON MEDAL. xh

AWARD OF THE WoLLASTON MEDAL.

In handing the Wollaston Medal, awarded to Prof. WatpremMar
CHRISTOFER Broacrr, F.M.G.S., to His Excellency Bensamin Voer,
Minister Plenipotentiary for the Kingdom of Norway, the PresipENnt
- addressed him as follows :—

Your Exce.Lency,—

lt is most fitting that the medal which bears the honoured name
of Wollaston, and was founded by that eminent and philosophical
mineralogist, should be awarded to Prof. Brogger, who is not only
an accomplished chemist and a skilful mineralogist, but a great
-petrologist. If he had published nothing but his work on these
‘subjects, he would stand in the first rank of living geologists. But
‘he has done far more. His researches on the Cambrian and Ordo-
vician rocks of his own country have proved him to be a brilliant
paleontologist and stratigrapher. His detailed mapping and inter-
pretation of the structure of the Christiania area and his explana-
tion of the origin of the Christiania Fjord, have proved him to be a
tectonic geologist of the highest order. His res2arches on the
differentiation of rock-magmas have made him one of our foremost
teachers of petrogenesis. He has conducted an exhaustive research
on the Glacial and post-Glacial changes in Southern Norway, and has
expressed his results so cogently that we seem to see with our own
eves the ice-sheets retreating, the seas advancing and retiring, and
to feel the climate slowly changing during the deposition of the
clays and shell-gravels of your country. He has brought his work
on the strand-lines into touch with the ages of man, and has even
endeavoured to express these later stages of geological time in terms .
of years. Nor has his life-work been devoted to science alone; he
has served his fellow-countrymen as a member of the National
Legislature and his colleagues as the Rector of his University.

But it is not so much the quantity as the quality of Prof.
Brégger’s work that constitutes his claim to the Wollaston Medal.
His scientific training has been so thorough, his insight so deep, and
his outlook so wide, that in every subject which he has touched his
work has become a mine of fact, a model of expression, an example
of close and accurate reasoning, and a revelation of new principles.
Jn an age of specialization he is a specialist, but a specialist in
almost every branch of his science. That it should have fallen to

VOL. LXVII. d

xii PROCEEDINGS OF THE GEOLOGICAL sociury. [May rot,

one man to do so much and so well almost passes belief, but our |
libraries are enriched by his books and memoirs, and the work of our
young men is inspired, improved, and encouraged by his example.
We ask your Excellency to transmit this Medal to Prof. Brégger,
and with it to convey to him the deepest respect of his British
colleagues, and the best wishes of his many friends in this country.

The Norwecian Mryisrer expressed his pride and pleasure in
receiving on behalf of his distinguished countryman and friend
the highest award which if, was in the power of so venerable and
learned a Society to confer, and read the following communication
which had been sent to him by Prof. Brégger :—

‘Twenty years ago the Geological Society of London did me the great honour
to award to me the Murchison Medal. ‘The Society now having awarded to
me its highest honour, the Wollaston Medal, I am led to hope that also-
during the two decenniums that have elapsed I have been able to yield some
contribution of general interest to geological science.

‘Allow me on this occasion to assure you, that no other appreciation could
haye been more unexpected or more valued by me than the unanimous award
of the Wollaston Medal by the Council of the Geological Society, an honour so
surprising to me, that evenin my dreams I could never have expected to attain
it. I am therefore so much the more grateful for this kind valuation of my
scientific results.

‘The roll of the Wollaston Medal, from the time of its first recipient, the
ereat’ master, William Smith, until this day, comprises an unsurpassed series
of founders and constructors of various branches of geological science. Looking
on this roll, comprising also a number of those who were my valued instructors:
in my youth—the few still living amongst them being now seniors and Nestors.
of their science—I obtain an excellent scale of the high importance of such
an appreciation from the oldest and most renowned Geological Society of the
world.

‘At the same time, these dear old illustrious names on the roll speak to me
as a sad and serious memento of the short lifetime that is left, a reminder to
devote the few years that may still remain for me to complete my main lifework:
“The History of the Eruptive Province of the Kristiania Region,” the finishing
of which, by the force of circumstances, has been interrupted and postponed by
official duties for several years.

‘Respectfully thanking you for this precious memento, I bow my head, and
will do my best to follow its voice. W: C. Breceant

‘ Kristiania, February 9th, 1911,

AWARD OF THE Murcuison MEDAL.

The Perstpent then handed the Murchison Medal, awarded to
Mr. Ricwarp Hirt Tippemay, M.A., to Prof. E. J. Garwoop, Sec.G.8.,

MURCHISON MEDAL. xliil

Vol. 67.] ANNIVERSARY MEETING

for transmission to the recipient, and addressed him in the following
words :— .

Professor Garwoop,—

Ever since the beginning of Mr. Tiddeman’s work for the Geo-
logical Survey on the borders of Yorkshire and Lancashire, he has
kept his eyes open to the observation of exceptional facts and his
mind employed in working out explanations for them. Thus he
has endowed our Science with the fertile suggestions which make
workers think on new lines. The excavation of the Victoria Cave,
with which he had so much to do, gave us valuable information
on the history of the Pleistocene Mammalia; his work on the
glaciation of North Lancashire still remains ‘a model and a basis
for Glacial work all over the country’; his observations on the
faunas of the Carboniferous ‘ reef-knolls’ of the North of England
have put on record a wealth of observation and reasoning which
will contribute no little to the solution of the problems presented
by those remarkable structures; and his researches upon the
raised beaches of Gower, covered with Glacial deposits, have ex-
tended the area of known Pleistocene movement beyond Yorkshire
and Cork. Those who have been with him in the field have good
cause to be especially grateful to him for the generosity with which
he has placed the riches of his knowledge at their disposal. He
has helped not only to advance Geology but to make geologists, and
in so doing he has invested his talent at compound interest.

As a member of the Geological Survey, and one of the last of
that body who served under Sir Roderick Murchison, he has well
merited the award of the medal which bears that honoured name.

Prof. Garwoop expressed deep regret, which he felt was shared
by all present, that a sudden attack of influenza had prevented the
recipient from attending in person, and read, in accordance with
Mr. Tiddeman’s request, the following reply :—

‘The award has given me the greatest possible pleasure and satisfaction,
and I owe to the President and Council my warmest thanks.

‘T regret that I have not. done more to merit it; but I hope that I may
take the Award as signifying that some of my former heresies have been more
or less accepted as orthodoxies by my present friends and colleagues, and for

this I may go on my way rejoicing. }
R. H. Tippeman.

d 2

xliv PROCEEDINGS OF THE GEOLOGICAL socinrTy. [May 1911,

AWARD oF THE Lyrtt MEDALS.

In presenting one of the two Lyell Medals, awarded this year,
to Dr. Francis ArrHur Batusr, F.R.S., the Prestpenr addressed
him as follows :—

Dr. Bararr,—

To devote one’s self to the mastery and elucidation of a single
group of organisms, and that a large one, demands in most cases
so close an application to the study, that neither time nor energy
is available for other studies or occupations. This, however, has
not been the case with you. Outside your own special orders of
the Echinoderma you have dealt with several other groups of the
Invertebrata, and have been entrusted with the writing of the
British Museum Handbook on the fossil members of this division
of the animal kingdom. You have paid attention to the pheno-
mena of denudation by wind, as well as to general stratigraphical
questions. You have travelled far and frequently in the pursuit of
your comparative study of the Foreign and Colonial Museums, and
have contributed much information and many valuable suggestions
on Museum management, organization, and arrangement to your
colleagues in this work. You have brought your ideas and methods
for the popular exposition of Geology before the public at the
recent International Exhibitions in London, and in more than one
case have been exceptionally successful in achieving your objects.
You have made yourself a recognized authority on zoological
nomenclature.

But these are all by-products. You have ever kept before your
‘mind the steadfast resolve to bring into order, to systematize and
classify, and to describe clearly, faithfully, and precisely, certain
important fossil forms of the Echinoderma, and especially the
Crinoids. I would especially mention your series of papers on
British Fossil Crinoids, your important memoir on the Crinoidea
of Gotland, and your latest published work on the Triassic
Echinoderms of Bakony. Nor must I omit to add your important
contribution on Echinoderma to Sir Ray Lankester’s Treatise on
Zoology.

In your task you have been so successful that the Council have
decided to ask you to accept this year a Lyell Medal, which was
intended by its founder to be awarded ‘for the encouragement
of Geology or of any of the allied sciences by which they shall
consider Geology to have been most materially advanced.’

Vol. 67.] ANNIVERSARY MEETING—LYELL MEDALS. xlv

Dr. Baruer, in reply, said :—
Mr. PrestpENt,—

I had thought of much to say on this occasion, but the generous
and flattering terms in which you have recounted the things that I
have done have made me think rather of those things that I have
left undone. If the little that I have done has seemed of such
service to Geology as to merit this high distinction, while I am
proud to receive it, I cannot forget the friends in all parts of the
world who have so greatly facilitated my work by the loan of
valuable specimens. And the thought of them again reminds me
of the material accumulated, but still untouched. A paleontologist
at the British Museum is often envied, much as Dionysius of
Syracuse was envied by Damocles. If any Damocles were to take
my place he would see, it is true, a rich feast of Cystids and
Crinoids laid before him. But the chains of office would per-
petually hinder him from feeding, and every day he would dread
the fall of a sword in the shape of a peremptory letter demanding
the immediate return of some necessary specimen.

It is my hope, Sir, that this award by so high a tribunal may
convince my friends and superiors that I really have made good use
of the rich material entrusted to me; certainly it will encourage
me to make my own future labours no less deserving of their
continued patience. For these reasons and for many others, which
must remain unexpressed, I offer to the Council my heartfelt
thanks.

The Prestpenr then presented the other Lyell Medal to
Dr. ArnrHur Watton Rows, F.G.S., addressing him as follows :—

Dr. Rowr,—

It is no small pleasure to me that it is my duty, as President of
the Geological Society, to ask your acceptance of the Lyell Medal
which the Council of the Society have awarded to you, in recognition
of the great service which you have rendered to British Geology by
your researches on the succession and distribution of the zones of the
English Chalk. Using delicate and refined means of your own for
the development of the fossils, and collecting the latter from the
successive horizons with the most scrupulous care, you soon con-
vinced yourself that the key to the evolution of the Echinoids and
the basis for their classification was to be found in their succession

xlvi PROCEEDINGS OF THE GEOLOGICAL socinty. [May 1911,

intime. The first important outcome of your work was the classic
paper on the evolution of the genus Micraster published by this Society
in 1899. The lines of advance in these organisms having thus been
made out, you proceeded to use the characteristic forms as time-
indices, with the result that you were able, not only to make a
satisfactory subdivision of the White Chalk in Kent, but to extend
the zonal lines thus marked out throughout the country. In this
manner you carried on the work so ably begun by Prof. Charles
Barrois, and erected a worthy superstructure upon the solid
foundations laid by him. The influence which your research has
exerted upon other investigators in stimulating them to work, either
in direct association with yourself or independently, but always
assisted and encouraged by your active help and sympathy, is
a sufficient testimony to its value.

Dr. tower replied in the following words : —
Mr. PRrestpent,—

That every man is glad to have his work recognized is, L
suppose, a truism; but, while I deeply appreciate the all too kind
remarks which you have just made, I cannot but feel that the
recognition is on far too generous a scale. Very warmly I welcome
the reference which you have made to my amateur colleagues 1n
the field. We have but one common aim, and that 1s to trace
the centres of distribution of species in the Chalk, together with
their vertical and horizontal range, and especially to work out the
fascinating problems in evolution in which that formation is so rich.
And, if a certain little biological indiscretion, which I had the
temerity to offer to the Council in the year 1899, has borne fruit
in this last direction, I shall not regret the anxious complications
which attended its somewhat protracted parturition.

But, while I claim all praise for the amateur worker, let us not
forget the labours of one whose philosophical and masterly grasp
of the whole Cretaceous System has laid us all under a lasting
obligation. I refer, of course, to Mr. A. J. Jukes-Browne.

All of us, however, professional and amateur worker alike, owe
our allegiance to, and draw our inspiration from, that great French-
man, Charles Barrois. But for him, we should still be floundering in
the pre-zonal chaos of a ‘ Chalk with flints’ and a ‘ Chalk without
flints.’ As I have said, when speaking in another place, I ask no
better verdict from posterity than to be regarded as a faithful

Vol. 67.] ANNIVERSARY MEETING—BIGSBY MEDAL. xlvil

exponent of Barrois. Higher praise no worker in the Chalk can
ask than this, nor can he attain to higher office.

And, Sir, in tendering to you and to the Council my grateful
thanks for this high honour, it only remains for me to say that
J accept it, not for my own merits, but as a recognition of the
splendid achievements of my fellow-workers in this most fruitful
field of investigation.

AWARD OF THE Bigspy MEDAL.

The PrestDEnt, in presenting to Prof. Ornento ABEL, Ph.D., the
Bigsby Medal, addressed him as follows :—

Professor ABEL,—

The Bigsby Medal has in former years been awarded to workers
im many branches of Geology; to stratigraphers, petrologists,
paleontologists, and to those whose special subject has been
tectonics or physiography : it has been given to the geologists of
many lands. It is, however, more than thirty years since it was
given to one whose chief work lay in the domain of Vertebrate
Paleontology, and it has never yet been awarded to a native of
your country.

In awarding it on this occasion, the Council wish to mark their
appreciation of your investigations upon the higher Vertebrata,
more especially on the Cetacea and Sirenia. Your great memoirs
on the Upper Miocene Toothed Whales of Belgium and on the
Sirenians of the Mediterranean Territory of Austria are admirable
examples of descriptive work, completed by philosophical deduc-
tions ; while your numerous smaller papers, both on mammals and -
on lower vertebrates, are full of suggestive speculations based on
a detailed study of all the available materials.

The vigour and thoroughness of the work that you have accom-
plished make it clear that, in the words of the Founder, ‘ you are
not too old for further work,’ while the number and excellence of
your publications prove that ‘ you are not too young to have done
much.’

Count ALexanpeR Hoyos, Secretary to the Imperial and Royal
Austro-Hungarian Embassy, expressed, on behalf of the Ambas-
sador, his Excellency’s regret at his unavoidable absence on that

xlviil PROCEEDINGS OF THE GEOLOGICAL soctnty. [May rort,

occasion, as well as his gratification that so signal an honour had’
been conferred by the premier Geological Society of the world upon '
his distinguished fellow-countryman, Prof. Abel, and thus for the
first time upon a native of Austria. i

Prof. Anrt, having requested permission to use the German
language in expressing his thanks, replied as follows :-— |

Herr PRasipent,—

Ich bitte, fiir die Verleihung der Bigsby Gold Medal meinen
wirmsten und tiefgefiithiten Dank entgegennehmen zu wollen.

Die Zuwendung der Bigsby Medal bedeutet fiir mich eine aus-.
serordentliche und unerwartete Khrung, und ich empfinde dieselbe
in ihrer ganzen Bedeutung. Ich schiitze diese Auszeichnung um so
hiher, als sie mir gerade von Seiten der Geological Society of
London verliehen wurde, der iiltesten und unbestritten angesehen-
sten geologischen Gesellschaft der Welt; ihre Mitgliederliste
umfasst seit ihrer Griindung bis auf den heutigen Tag Namen,
deren Triiger auf dem Gebiete der Geologie und Paliiontologie
unsere Fiihrer und Meister gewesen sind.

Ich bin stolz darauf als der erste Cisterreicher dieselbe Medaille
erhalten zu haben, welche 1877 an Othniel Charles Marsh und
1879 an Edward Drinker Cope verlichen wurde. Aber diese’
Erinnerung weckt in mir die Besorgnis, ob ich imstande sein werde,
mich wie Marsh und Cope in Zukunft der mir yerliechenen Auszeich-—
nung nicht unwiirdig zu erweisen.

Seit einer Reihe von Jahren mit Untersuchungen tber fossile
Vertebraten beschiaftigt, war es stets mein Bestreben, ihre genet-
ischen Zusammenhinge und Entwicklungswege sowie die Geschichte '
ihrer Anpassungen zu verfolgen. Auf dem Wege weiterschreitend,
den mir mein hochverehrter Freund Louis Dollo gewiesen hat, will
ich auch ferner meine ganze Kraft diesen Untersuchungen zuwenden,
um mich der mir heute zuteil gewordenen Ehrung nicht unwurdig
gu erweisen ; die Bigsby Medal wird ein neuer Ansporn fur mich:
. sein, in meinen wissenschaftlichen Arbeiten nicht zu erlahmen.

Vol. 67.] ANNIVERSARY MEETING-——-MURCHISON FUND. xlix

AWARD FROM THE Wo.uaston Donation Funp.

The Presipunr then presented the Balance of the Proceeds of the
Wollaston Donation Fund to Prof. Owrny Tuomas Jonzs, M.A.,
addressing him as follows :—

Professor JonzEs,—

Up to within the last few years, the wide-spreading and rugged .
expanse of Central Wales was tinted upon our geological maps .
of a uniform pink colour, almost as if it were composed of the
strata of a single sub-formation. But, little by little, geologists of
the younger generation have been working out the details of
its complicated structure, collecting the fossils, and bringing its
component rock-groups into line and harmony with their zone-
fellows elsewhere. In this work of reformation you have taken a
full share. While still a member of the Geological Survey, you
devoted your holidays to the enthusiastic study of these complicated
strata of your native land, and in your Plynlimmon paper you have
most successfully unravelled the sequence and structure of that
‘heart of Mid-Wales’ and of much of the ground to the west. I
have much pleasure in handing to you the Balance of the Proceeds
of the Wollaston Fund, which the Council have awarded to you, in.
recognition of the good work that you have done, and as an
incentive to you to complete it,—a task which will be rendered
easier by your appointment as Professor of Geology in the Um-
versity College of Wales at Aberystwyth.

AWARD FROM tHE Murcuison Grotocican Funp.

In presenting the Balance of the Proceeds of the Murchison
Geological Fund to Mr. Eneaar Srertine Cosson, F.G.S., the
Prestpent addressed him in the following words :—

Mr. CopspoLtp,—

Although the County of Shropshire was to Murchison a veritable
Golconda, he was not able to remove all its treasure or to wrest all
its secrets, but left a generous reward for his many successors.
Among them, by your excavations in a district rendered difficult
by earth-movement and thick soil-covering, you have succeeded in

PROCEEDINGS OF THE GHOLOGICAL socipry. |May 1911,

obtaining a new Cambrian sub-fauna and an array of new genera
and species of trilobites. You have not only made important
contributions to what was hitherto known of the local succession
of the subdivisions of those ancient rocks, but you have by your
figures and descriptions added much to our previous knowledge
of their fossils. It is appropriate that the Murchison Fund should
pass into ‘Siluria’ and to one working on Older Paleozoic rocks,
as a token of the good-will of your fellow-workers, a mark of their
pleasure in your achievement, and an expression of their confidence
in your future work.

AWARD FROM THE LyeLt GronocicaL Funp.

The Presipenr then presented to Dr. CHartus GILBERT Cunus,
F.G.8., the Balance of the Proceeds of the Lyell Geological Fund,
addressing him as follows :—

Dr, Cun11s,—

I need hardly express the pleasure that it gives me to hand
the Balance of the Lyell Fund to a colleague for whom I have so
much respect, and in whose judgment and ability I place so much
confidence. You are able to look back upon a great number of
students who have passed out into the world bearing the marks
of your training, and you have reason to be proud of the work
that they are doing. Your original contribution to the study of the
core of the Funafuti Boring, with its careful record and explanation
of the occurrence of calcite, aragonite, and dolomite therein; your
work on the Forest of Dean and May Hill; and your discovery of
the occurrence of dolomite crystals in the Keuper Marls, have all
been the fruit of painstaking research, with the gratifying result
of forwarding the researches of others. All those who have heard
you lecture on your own work or on other geological subjects,
have been greatly impressed by your careful choice of matter, the
charm of your style, and the lucidity of your expression. Certainly
this Award is given to one by whom ‘Geology has been materially
advanced,’

Vol. 67.| ANNIVERSARY MEPTING—BARLOW-JAMESON FUND. hi

AWARD FROM THE Bartow-J AMESON FuND.

In presenting an Award from the Proceeds of the Barlow-
Jameson Fund to Mr. Joun Frepertck Norman Green, M.A., the
Presivenr addressed him in the following words :—

Mr. GrEex,—

It is not often that it is given to a geologist to succeed in
producing conviction by a single paper, still less by his first
contribution to the Science: but such has been your good fortune
in the paper published by this Society on the rocks of St. David’s.
The appropriateness of your methods, your careful recognition of
lithological horizons, the accuracy and detailed minuteness of your
mapping, even the careful selection of the most conclusive spot for

excavation, have engendered such confidence in the result, that we

may regard as solved one of the chief difficulties in a most complex
region. ‘The Council have made to you an Award from the Barlow-
Jameson Fund ‘ for the advancement of Geological Science,’ in the
assurance that you will carry the same accuracy and delicacy of
work into other fields.

hi PROCEEDINGS OF THE GEOLOGICAL sociETy. [May 1911,

THE ANNIVERSARY ADDRESS OF THE PRESIDENT,
Prof. Witt1am Waitendkap Warts, Sc.D., M.Sc., F.R.S.

During this year death has laid his heavy hand more lightly
than is his wont upon our ranks. It is not often that a year
passes without the loss of one or more of those eminent men whose
names adorn the lists of our Foreign Members and Correspon-
dents. Prof. W. P. Blake, though a citizen of the United States,
was on our home list; and our other losses include Charles Bird,
Arthur Brown, Dr. T. Cooke, E. Cross, Prebendary W. H. Egerton,
the Rev. de Charles Evans, C. E. Fox-Strangways, G. R. Godson,
T. M. Heaphy, J. C. Melliss, Captain G. E. Shelley, W. Smethurst,
Charles Smith, A. H. Stokes, F. Tendron, Major-General W. EK.
Warrand, the Rey. R. B. Watson, the Rev. G. F. Whidborne, and’
J.T. Young. Notices of the lives of those who have been closely
associated with the advance of Geology are given below, and to
them have been added notices of the following :—J. Randall, a
Fellow until 1877; J. R. Dakyns, who, though he published’
papers in our Journal, never actually joined the Society ; and’
T. R. Polwhele, a Fellow who died in 1909. For the notice of the
last I am indebted to Mr. H. B. Woodward, and that of J. R.
Dakyns is founded on a memoir written by Mr. G. W. Lamplugh
for the Yorkshire Geological Society. The list contains the name
of one centenarian and of one Fellow who attained the ripe age of
98 years ; the youngest died at 64, and the average age of those
that I have been able to trace is 76.

The Rev. Wiitiam Heyry KEeurton, Prebendary of Lichfield,
was born on November 13th, 1811, and was the fourth son of the
Rey. Sir Philip Grey Egerton, the ninth baronet. He was educated
privately, graduated at Brasenose College, Oxford, in 1854, and
was elected to a Fellowship at his College. He was nominated by
Lord Brownlow to the Rectory of Hllesmere (Salop) in 1845, and
transferred to the Rectory of Whitchurch in the following year,
a cure which he held for 62 years until his retirement in 1908. In
that year he answered with his own hand a letter of congratulation,
which the Secretary was instructed by the Council to write on his
birthday to one who for many years had been the ‘ Father’ of the
Society. He was a Fellow for 78 years, and died on December Ist,
1909, at the age of 98 years. His only communication to the

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. hi

Society was a letter written to Sir Charles Lyell as Foreign
Secretary in 1834, on the delta formed by the river Kander, since
it was turned into a new course in 1713. This was published in
vol. ii of the Proceedings.’

Joun Ranpatt was born at Broseley(Shropshire) on September Ist,
1810. He early attained considerable skill in the art of painting
on china, and, adopting this as his profession, was engaged in it
until in 1891 his failing eyesight compelled him to give up the
work. His special branch was the painting of birds, in which
he obtained great proficiency. Joining the Geological Society in
1863 and remaining a Fellow until 1877, he published one paper
in our Journal in conjunction with G. KH. Roberts, recording
their joint discovery of the Upper Ludlow Bone-bed in Linley Brook,
near Bridgnorth. Most of his other papers were contributed to
the ‘Colliery Guardian,’ and referred to the Midland iron-ores,
His literary activity was considerable, and among his works the
‘ History of Broseley,’ the ‘Severn Valley,’ and the ‘ Clay Industries’
contained chapters and references dealing with the geology of the
Shropshire Coalfield and its borders, on which he had made himself
an authority, mainly by his own field observations. At the 1851
Exhibition he received a bronze medal for his collection of minerals
and fossils, and in 1867 he was sent by the Society of Arts to the
Paris Exhibition, where he reported on the manufacture of both
pottery and iron. After he had passed the age of 90, he dictated
to his daughter the volume on the arts and industries of Shrop-
shire for the ‘ Victoria History’ of the county. On June 7th,
~ 1909, the freedom of the Borough of Wenlock was conferred on
him in his 99th year, and it is stated that he signed the Borough
Roll without the aid of spectacles. He lived to celebrate his
hundredth birthday, but died shortly afterwards.

Tuomas Roxpuren Potwuere, M.A., whose death took place at
Polwhele, near Truro, on September 2nd, 1909, was born in 1831,
and educated at Cambridge, where his interest in geology was
aroused by the teachings of Sedgwick. In 1857 he joined the staff
of the Geological Survey under Murchison and Ramsay, and in the
following year became a Fellow of this Society. During his official

1 For the particulars given in these notices I am much indebted to the
‘Geological Magazine,’ ‘ Nature,’ the Proceedings of the Yorkshire Geological
Society, the ‘Times,’ and to several newspapers.

liv PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1og1t,

field-work he was occupied in parts of Hampshire, Surrey, Oxford-
shire, and Buckinghamshire, and contributed notes to Memoirs
prepared by his colleagues W. Whitaker and A. H. Green. An
able and painstaking worker, he remained but five years on the
Geological Survey, as he succeeded to the Polwhele estate in
1862. Thereafter his duties as a landowner occupied his chief
attention; he became a Justice of the Peace and Deputy Lieutenant.
He was, however, chosen President of the Royal Geological Society
of Cornwall in 1896 and 1897, and delivered addresses on ‘The
Relation of other Sciences to Geology’ and on ‘The Physical
Geology of the Earth.’ [Bees

Major-General Witiiam Epmunp Warranp, R.E., was born in
1831. He passed through the Indian Mutiny, and in 1860 was
appointed head of the Civil Engineering College in Calcutta. He
became a Fellow of this Society in 1859, and died on October 22nd,
1910, at the age of 79.

Captain Groner Ernest SHELLEY, a nephew of the poet, joined
this Society in 1862. Born in 1840, he entered the Grenadier
Guards in 18638, and, after a short service, retired. After his
retirement he was attached to a Commission sent out by the
Government to South Africa on a geological survey. His interest
was, however, attracted by the study of ornithology, and to this
he devoted his chief attention, publishing several important works
and monographs on the subject. He died in December, 1910.

The Rev. Roserr Boog Watson became a Fellow of the Society
in 1864. He was a Chaplain to the Forces, and later on was
Minister of the Scottish Church in Madeira. He wrote a paper,
published in abstract in the Quarterly Journal for 1866, in which
he advocated a marine origin for the Parallel Roads of Glenroy,
in opposition to the views expressed by Agassiz and Jamieson.
He also wrote on the Boulder Clay at Greenock and the eee
drifts of Southern Arran. He died in June, 1910.

TuHEoporE Cooke, C.I.E., LL.D., M.A., F.L.8., died on November
5th, 1910, at the age of 74. He had been a Fellow of this
Society since 1866. After winning high distinction at Trinity
College, Dublin, he went out to India as an engineer, and there
completed several important works, including the iron bridge at

Wol!67.'| ANNIVERSARY ADDRESS OF THE PRESIDENT. lv

Bassein, 4312 feet long. He was appointed Principal of the
Poona College of Science, and also Director of the Botanical
Survey of Western India. He retired from India in 1893, and
was for the next three years Technical Sub-Director of the Imperial
Institute.

Cuartes Enwarp Fox-Srraneways died on March 5th, 1910, at
the age of 66. He was born at Rewe, near Exeter, where his
father, the Rey. Henry Fox-Strangways, a grandson of the first
Earl of Ilchester, was Rector. He was educated at Eton, and,
proceeding afterwards to the University of Goéttingen, he studied
chiefly the sciences of mineralogy, chemistry, and physics. Here
also he saw something of the war of 1866, in the course of which he
assisted Sartorius von Waltershausen, the Professor of Mineralogy
and Geology, to conceal his* collection of minerals, in order to
prevent it from falling into the hands of the belligerents. In the
following year he received an appointment as Assistant-Geologist
to the Geological Survey, under Murchison. He attained the rank
of Geologist in 1879, and was promoted to District-Geologist in
1901. He joined the Geological Society in 1873, served on the
Council from 1905 to 1908, and was for a couple of years Secretary
of the Geological Society Club.

The bulk of his published work is contained in the Memoirs of
the Geological Survey, and he read no papers to this Society. He,
however, communicated many papers to the Yorkshire Geological
Society, to the Leicestershire Literary & Philosophical Society,
and to other local institutions. After some early work near
Todmorden and across the Yorkshire Coalfield, he surveyed a
considerable area near Harrogate and Knaresborough. Then,
settling at Scarborough, he carried his work across the Vale of
York, to the Jurassic and Cretaceous rocks of the Yorkshire
Wolds and Moors. Many of his maps were published on the
6-inch scale as well as the ordinary l-inch scale, and some of
his Memoirs have had the unusual distinction of passing into a
second edition. His sympathies were by no means confined to the
solid rocks, but he was keenly interested in physiographic questions
and made many important observations and suggestions on the
glacial phenomena of the Vale of York, the Vale of Pickering, and
the Yorkshire Moors. He closed his official Yorkshire work with
the publication of his contribution to the Memoir on the Jurassic
Rocks of Britain, two portly volumes on the Jurassic Rocks of
Yorkshire.

lyi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May rgr1,

On his transfer to the Midlands in 1889 he moved his residence

to Leicester. Here he was engaged on the re-survey of parts

of the Coalfields of Central England with the intervening ground.
Besides several sheet-memoirs, he was entirely responsible for the
Memoirs on the South Derbyshire and Leicestershire Coalfields.
From 1901 onwards he was in charge of the officers engaged in
surveying the Midland District, until in 1904 he retired from the
service. While resident in Leicester he took much interest in the

“work of the Leicestershire Literary & Philosophical Society, and

especially in its excursions, many of which he planned and directed.
The longer excursions of 1903 and 1904 to Scarborough and Whitby
were led by him. It was at Leicester that the present writer had
the pleasure of making his acquaintance, and of working with him
on the geology of Charnwood Forest.

Weakened health, due to an affected heart, gradually impaired
his wonted activity, and made him glad to retire when he had
reached the age-limit. He moved to Hampstead, and although un-
able to take part in field-work, he carried on his literary work
to the end. He succeeded in practically completing an exhaustive
bibliography of Yorkshire, which it is to be hoped wili soon be
published ; but he was unable to finish the Memoir on the Thick-
nesses of the British Formations, on which he had begun to amass

material.

All who knew Fox-Strangways were charmed with his gentle-
ness and modesty. A remarkably steady, systematic, untiring,

-and persistent worker, he covered his ground in the field with

singular thoroughness, and his maps probably contain as much
careful and conscientious record of fact as those produced by any
Survey Officer. His charming disposition and unruffled demeanour
endeared him to all who had the privilege of enjoying his hospi-
tality or of accompanying him into the field. But this was

‘combined with a modest reserve which it was most difficult to

break down, and there were very few who could feel that they
knew him intimately. Those he trusted he trusted absolutely.
In his quiet, persevering way he got through a very great amount
of work, most of which he succeeded in finishing ; and itis by such

~men as he was that some of the best of the world’s work is done.

ArtHuR Henry Sroxes was born in 1842, became a mining
engineer and colliery-manager in the Staffordshire and Derbyshire
coalfields, and explored and reported upon coalfields in Sweden.

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. ly1i

He was appointed an Inspector of Mines in 1874, and was pro-
moted to be Chief Inspector in the Midland District in 1887.
During this period he on several occasions performed acts of great
bravery in the rescue of men entombed in mines. In 1879 the
Silver Medal of the Order of St. John of Jerusalem was awarded
to him, and in 1882 the Albert Medal of the First Class. He
joined this Society in 1874, and in 1880 published his only paper
in the Quarterly Journal, ‘On the Coal found at Siiderde in the
Farée Islands.’ He made numerous important contributions to
mining journals on lead-mining, safety-lamps, and economic
» geology, and wrote a history and geology of Castleton. He died
at Derby on November 10th, 1910, in his 68th year.

Witi1am Paipes Brake was born in New Yorkfon June Ist,
1826, and received his scientific education at the University of
Yale, from which he graduated in 1852, among his co-graduates
being Prof. Brush and Prof. Brewer. From 1854 to 1856 he acted
as Geologist and Mineralogist on the explorations for the proposed
Pacific Railway, reaching California shortly after the discovery of
gold there. He carried on mining explorations in North Carolina
and Georgia in 1860, and from 1861 to 1863 was employed by the
Imperial Government of Japan in an examination of the mineral
resources of that country. He also visited Alaska in 1867. In
1864 he became Professor of Geology and Mineralogy in the
College of California, and, later, he was appointed Professor of
Geology and Director of the School of Mines at the University of
Arizona, being made Emeritus Professor in 1895. He was also,
for some years, Territorial Geologist of Arizona.

He joined the Geological Society in 1876, and remained a Fellow
until his death on May 22nd, 1910. His earlier papers were
devoted to mineralogy, a subject in whieh he maintained his
interest up tothe end of his life. Other subjects on which he wrote
comprise infusorial earths; deserts and the action of /the sand-
blast; the mammoth, tapir, Hipparwn, and other mammals; the
ores of gold, silver, iron, mercury, and tin; the Rocky Mountains,
California, Arizona, Oregon, and Wisconsin; coal, , glaciation,
earthquakes, and oscillations of level; and he even contributed
a paper on the Pliocene skull of California. He was also the
author of a volume on ‘The Production of the Precious Metals’.

1 Taken in part from Am. Journ. Sci. ser. 4, vol. xxx (1910) pp. 95-96.

VoL. LXVII. e

viii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May ro11,

The Rev. Grorcr Frrris WHrIpBoRNE was descended from
Sir Richard Whidborne, one of the Devonians who provided ships
to fight the Spanish Armada, and a founder of the Colony of
Newfoundland. He was born in 1846, and died somewhat suddenly
on February 14th, 1910, in the 64th year of his age. My first
duty as incoming President of the Socicty was to attend his funeral
at his beautiful house at Hammerwood, in the heart of the Weald.
He joined the Society in 1876, and several times served on its
Council and on the Council of the Palzontographical Society. He
contributed papers on Inferior Oolite fossils and on the geographical
distribution of the Plesiosaurs to the Quarterly Journal; printed
lists of Devonian fossils, largely from his own collection, in the
Proceedings of the Geologists’ Association; described fossils of
Lower Devonian if not Silurian affinities from the Morte Slates for
Dr. H. Hicks ; and published papers dealing mainly with Devonian
fossils in the ‘Geological Magazine. But his great geological
work was contributed to the Palzontographical Society. At first
he contented himself with sending numerous brachiopods from his
collection to Thomas Davidson to deal with in his great Monograph.
But, later, he was prevailed upon to undertake the description of the
entire fauna of the Devonian Limestones and of the Marwood and
Pilton Beds in a single monograph. This was published, and forms
a complete work in three bulky volumes, the excellent illustrations
of which were, many of them, contributed at his own expense.

Much of his life was occupied with hard and self-sacrificing
labour on behalf of the National Church; but the only benefice
he held was that of St. George’s, Battersea, which he retained for
eight years and resigned in 1896. He was connected with many
Church Institutions, most of which profited by his open-handed
generosity. He took an especial interest in the Church Missionary
Society and the Victoria Institute. It was only a comparatively
short time before his death that he bought his estate at Hammer-
wood and settled down in residence there. His valuable collection
of geological specimens and his library have been presented by
Mrs. Whidborne to the Sedgwick Museum at Cambridge. His
death removes one whose companionship was most genial, who
acted as a generous benefactor to several geological causes, a
paleontologist of mark, and a man beloved by many friends.

Tuomas Musgrave Heapuy, who had become a Fellow of this
Society in 1876, died on March 29th, 1910. He was for many
years consulting electrical engineer to the Phoenix Fire Insurance

<

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. lix

Company. He had volunteered in the early sixties in the cause
of Italian liberation, and fought under Garibaldi. He rendered
considerable service to the Society, by giving advice and super-
vising estimates, when electric light was installed in the Apart-
ments at Burlington House in 1896.

Caaries Birp was born in January 1843. He was a graduate
of the University of London, and, while Second Master at Bradford
Grammar School, studied and wrote on the Red Beds at the base
of the Carboniferous Limestone in the North-West of England.
In 1881 he published ‘ A Short Sketch of the Geology of Yorkshire.’
About this time he became Head Master of the Mathematical
School in Rochester, and, while there, published an ‘ Elementary
Geology’ and an ‘ Advanced Geology.’ He also published papers
on local geology in the ‘Rochester Naturalist,’ and assisted in
conducting excursions of the Geologists’ Association. He was
President of the Rochester Naturalists’ Society for four years,
between 1883 and 1889. He joined the Geological Society in 1882,
and remained a Fellow until his death on April 11th, 1910, at
the age of 67.

Joun Rocute Dakyns was born in 1836 in the West Indies.
He was educated at Rugby and at Trinity College, Cambridge,
whence he graduated in the Mathematical Tripos. He joined the
Geological Survey in 1862, and was promoted to the rank of
Geologist in 1868. His chief work was in the Derbyshire and
Yorkshire Coalfield, the Plain of York, the Pennine Chain, and
the Eden Valley. In 1872 he read a paper to this Society on the
Glacial Phenomena of the Yorkshire Uplands. He was transferred
to the Scottish branch of the Survey in 1884, and in connexion
with his work there he communicated his second paper to the
Society, ‘On the Plutonic Rocks of Garabal Hill & Meall Breac,’
which was written in conjunction with Dr. Teall. His last two
years of Survey work were spent in the South Wales Coalfield,
and he retired in 1896 to Snowdon View, Beddgelert, where he
occupied his leisure strenuously in mapping the greater part of
Snowdon on the 6-inch scale. He died on September 27th, 1910,
at the age of 75.

Although he never joined this Society, he communicated
numerous papers to the ‘Geological Magazine’ and to the York-
shire Societies, but his publications, even when those contained in
maps and memoirs are added, by no means represent the large

e2

isc PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May rort,,.

amount of original work which he carried out. And even this.
latter does not give a true measure of his influence for the good of
his science in his insistence on extreme closeness of observation.
and accuracy in reasoning.’

The chief geological event of the past year has been the holding
of the Eleventh International Geological Congress at Stockholm.
The Congress was attended by several Fellows of the Society,
including the ex-President and the Treasurer. An extremely
interesting and well-organised series of excursions was planned
and carried out, the meetings were of considerable importance, and
the event was further marked by the issue of valuable publications
dealing with the geology of Sweden and with the distribution of
iron-ores,

In our own Society the event of first importance has been the:
unanimous decision of a Special General Meeting to utilise the
space now occupied by the Museum for an extension of the Library,,
and to offer the Society’s collection of minerals, rocks, and fossils,
with a few exceptions, to one or more of the National Museums of
the country.

This is a welcome solution of the problem which has agitated
the Fellows for many years. The accommodation provided by the
Apartments is limited, and it is the duty of the Society to employ
the space generously placed at its disposal by the Government in
the way which will contribute most to the welfare of the Science.
The collections occupy a great deal of space, even packed away as
they now are. For their proper display much more space than can
be given to them would be required, while they would need the.
constant care and attention of a curator, and the expenditure upon
them of an amount of money which the Society could not afford
without crippling seriously one or more of its other spheres of activity.

For many years after the Society was founded geological museums.
were scarce and difficult of access. It was at that time, therefore,
clearly the duty of the Society, and its best service to geology, to
offer an asylum to specimens of scientific value and importance, to.
form the nucleus of a great geological museum, and, at the same
time, to afford to students and investigators facilities for the
examination and comparison of specimens and types.

1 Further particulars will be found in Geol. Mag. dee. 5, vol. vii Ca.
p. 575; and in Proc. Yorks. Geol. Soc. vol. xvii (1910) p. 159.

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. }xi

But times have changed. There are great national museums,
one of the duties of which is to contain and conserve collections of
geological specimens, and to make them accessible to investigators ;
and there are teaching institutions at which students are pro-
‘vided with the geological material necessary for their studies.
There is not, therefore, the pressing need that formerly existed for
the Geological Society to maintain a museum of its own.

On the other hand, the Society has been gradually accumulating
‘what is probably the finest collection of geological literature in the
world. The Society’s exchanges, its acknowledged position in the
Science, and the sums devoted to the upkeep of the Library, combine
to make the annual accumulation of books a very formidable matter,
but one which redounds to the credit of the Society, adds to its
reputation, and makes its Fellowship of great value to geological
workers. The importance of the Library is further considerably
enhanced by the annual publication of the list of additions to it
in the form of ‘ Geological Literature.’ The vast service that
this Library renders and is capable of rendering to Geological
Science makes it imperative that the Geological Society should
foster its growth by every means in its power, should secure the
presence in it of all works of importance, should catalogue them
properly and continuously, and render them easily accessible to
those who wish to consult them. This cannot be properly carried
out in the room at present devoted to the Library, which has already
overflowed into several other of the rooms in the House. An
additional series of rooms, worthy of the object and suitably fitted
up, is an absolute necessity if the Society is to do its duty by its
Library. And the only rooms available are those at present devoted
to the Museum.

It has, therefore, been thought well by the Society to pass the
resolutions mentioned in the Annual Report, and to commit to the
Council the task of drafting a scheme for the disposal of the
contents of the Museum and of providing in their place for additional
Library accommodation. The passing of that Annual Report by
the Anniversary Meeting to-day may be regarded as confirming
these resolutions.

The contents of the Collection have been given to the Society
by a very large number of donors throughout the century of its
existence. They consist in part of minerals, rocks, and fossils,
illustrating papers read to the Society; in part of specimens
collected by Fellows in their travels in Foreign countries and in
the Colonies; and in part of material collected in the working out

)xii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1911;

of the geology of this country. The material has been given to
the Society in the trust that the Society would make such use of
it as would be of greatest benefit to the Science. Much of it is
of high intrinsic value; but its scientific value to experts is far
higher, for there are in it not less than 2000 types and figured
specimens. It is, therefore, the documentary evidence of the
advance of Geology in this country, and it is exceptionally precious
on that account. It is clear that, as we have resolved, it ought
only to go to one or more of the National Institutions.

Moreover, it must go with the proviso that it shall be readily
accessible to those who are most capable of making good use of it—
specialists in Geology, Paleontology, and Mineralogy. Its contents
should not be scattered, but should be kept within the area of a
single city. And it is extremely important that that city should be
so situated as to be the most convenient possible to the numerous
workers who will make use of the collection.

Considerations like these will doubtless be taken into account by
the Council, in drawing up a scheme to be presented to the Society
for its decision.

GroLoGY AS GroGRAPHICAL EVoLuUrIoN.

THe broadest and most popular conception of ‘Geology’ is the
‘History of the Earth.’ And to a large extent this conception is
justifiable, for it is to the elucidation of Karth History that all
branches of the science are contributory, and from a knowledge
and interpretation of the details of this history that the applications
of Geology proceed.

The successive time-periods of much of that history have long
since been broadly defined and their relative chronological order
established by the study of the characters, sequence, and dis-
tribution, of the geological formations, and their grouping into
those grander assemblages the Geological Systems.

In the Geological Record thus arrived at and universally accepted,
one of the most striking and fundamental facts is the preservation
in rocks of the relics of once-living animals and plants, and it
was only natural that, immediately these objects were admitted
to be of organic origin, they should be eagerly collected, classified,
compared with modern forms and with one another, and arranged
geologically in the order in which the rocks containing them were
deposited.

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDEN’. Lxilt

As the result of more than a century’s work upon fossils we are
now well assured:—(1) That each Geological System is charac-
terised by a distinct fauna or flora; (2) that each such fauna or
flora is, on the whole, an improvement on that which preceded it ;
and (3) that the relation of a fauna or flora to its successor is of
an ancestral character.

The numberless facts collected by geologists, and the inevitable
conclusions towards which they point, admit of their simplest
and most harmonious explanation on the theory of evolution, and,
indeed, they have furnished by far the strongest evidence in favour
of this doctrine. As yet they have not enabled us to discover the
machinery by which the evolution of life was brought about, but
we feel confident that on the chain of past life hangs the key both
to the conflict between existing views and to those future advances.
in knowledge and opinion by which the mystery of evolution will
be ultimately solved.

The year 1909—the jubilee of the ‘ Origin of Species’ as well
as the centenary of its author—was marked by important memoirs
by Sir Archibald Geikie and Prof. Judd on the geological work
of Darwin himself; while last year Prof. Judd showed that the
broad and solid foundations on which Darwin built were laid for
him by Scrope and Lyell.

(1) The Use of Geographical Parallels.

While the Geologist has been able to infer from the facts at his.
command, not only that an evolutionary chain of life has existed on
the earth, but that in the past, as in the present, biological conditions.
of competition, food-supply, etc., have varied from time to time and:
from place to place, he has, in demonstrating the immense varia-
tions in physical environment that have taken place in geological
time, made a third and at least equally important contribution to.
evolution. He has proved that the climate, the relative position
of land and water, the height, the slope, and the very lithological
composition, of the land have been in a state of perpetual flux from
the earliest periods to the present.

This he has done by his acceptance and employment of the
fundamental principle of uniformitarianism, that the present 1s the
key to the past; by his careful comparison of the phenomena of
the dead past with the results of the living processes of the present ;
by a study of the denudation and deposition, of earth-movement
and vulcanicity, of the birth, and growth, and death of land-forms.

ee rs he oe RM ei se

lxiv PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1911,

From these comparisons has arisen a general knowledge of the
laws which govern the formation of rock-masses, their deformation
in building up the earth-crust, the interaction of internal and
external forces, the share of organic and inorganic agencies, the
‘lapse of waves and the life of stones.’

It has often happened, however, that the application of a general
principle on a far minuter scale than was contemplated by its
founder has led on to a new development and to new results wholly
undreamed of by him. This has been especially true of the method
taught by the uniformitarians.

All British geologists must admit that they owe to Godwin-
Austen and Ramsay such an ‘intensive’ application of uniformi-
tarianism. ‘They showed the interest appertaining to distinctive
and exceptional phases of present-day physiography, when considered
in relation to the abnormal characteristics of certain of the
geological formations. They seem to have brought us nearer to a
vivid visualisation of the past, they transformed stratigraphical
into historical Geology, changed the formations from ‘the cemeteries
of once-living organisms’ into a world pulsating with the teeming
life of forgotten ages, a world in which we could seey as in a series
of impressionist pictures, the lakes and mountains, the rivers and
volcanoes of the past.

There were, of course, objectors who argued that no attempt to
find a complete parallel between any particular local or regional
phase of the past and a modern, existent, representative was likely
to be successful in every detail; that the exact grouping of all the
circumstances was not likely to recur at any one spot; that, at best,
geographical parallels to explain past geological phases were only
likely to be found by the comparison of several existing areas. All
this may be freely admitted. Nevertheless the search gives a
keener incentive for the minute examination of details by both
Geologist and Geographer; a stimulation to the imagination to
attempt the explanation of unsolved difficulties; a new impulse
for the Geographer to prosecute more detailed research in areas
already ‘discovered and explained’ ; and a means for the expression
of some of the results of our science in a language and imagery
which are more likely to be understanded of the people than the
terminological exactitudes in which we are accustomed to clothe
our conclusions.

My belief is that the method is not by any means exhausted, and
that with our growing knowledge of the surface of our earth on the
one hand and of the rocks on the other, we may hope to advance

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. lxv

much farther in the interpretation of the physiography of the past.
But our guide must be the union of delicate stratigraphical research
with minute geographical work. We must be accurate in our
geological facts; but we may, as Darwin advised us, speculate
freely, and our lode-star should be the injunction to ‘travel,
travel, travel.’

(2) The Cycle of Earth-Movement.

The geological record of a single region such as Britain is a
chronicle of two chief’ classes of events. On the one hand, the
great masses of sediment record periods of downward movement,
more or less interrupted, during which the area was covered by the
sea or other widely extended waters; while, on the other, the
physical breaks in sedimentation, and particularly the great un-
conformities, furnish us with evidence of uplift into the regions
of denudation, mostly areas of land or relatively shallow water.

The study of the British record tells of many pulsations of
movement, varying in direction and intensity, but each one
accompanied, on the whole, by cycles of phenomena, similar in their
march of events, but varied in other details by the external conditions
under which they were developed.

(3) The Cycle of Deposition.

The general succession is approximately as follows :—

(i) A deeper-water or ‘ thalassic’ period, with widespread, even-
bedded, fine-grained, seaward, sediments, succeeding or alternating
with organic deposits.

(ii) A shallower-water period, with ‘deltaic’ and littoral, shore-
ward, deposits of mudstones and sandstones more limited in their
distribution, but laid down on smooth areas, associated with
phenomena of contemporaneous erosion and overlap, with increasing
coarseness of grain and with decreasing numbers of organic
remains.

(iii) A period of rising and uplift giving origin to continents,
mountains, and lakes, to rapid denudation filling the hollows thus
formed with irregular masses of coarse-grained, ‘ terrestrial,’ land-
ward, deposits which are variable in their composition and source,
difficult to correlate, characteristically poor in organisms, and
frequently associated with sheets or masses of locally derived
and angular or slightly rounded materials.

(iv) A period of sinking and depression, during which the sea

(i
{
th
i

= Ixy PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May rgr1,

gradually obtains ingress to the lower lands and lake-areas,
converting them into gulfs and estuaries, and lays down in them
sheets of shoreward but ‘estuarine’ deposits, smooth and flat
over the deposits of the preceding period, and made of débris
provided by the continued activity of the agents of erosion. But,
owing to the irregular contour of the drowning land, every sheet
so laid down will be of irregular shape, each one will pass at.
its edges into coastal deposits, and each will transgress during
the submergence with increasing overlap beyond the preceding
deposit and against the old land until that old land is at length
completely lost under the sea.

(v) Finally, the old land sinks completely under the sea, deeper-
water (‘ thalassic’) conditions recur, and the cycle is complete.

(4) Difficulties and Exceptions.

While the normal succession of events in a cycle of deposition
will be that just described, normal stratigraphical phenomena by
no means always obtain. For example :—

(a) The uplift may be of epeirogenic rather than orogenic type ;
the sediments may not be much disturbed in their lie, and denu-
dation may be content only to strip off the upper portion of recently
formed deposits. Unconformity will be slight, the break in sedi-
mentation inconsiderable, and the newly formed sediments not
strikingly different from those which precede them.

(6) The uplift, if orogenic, may be of such long duration that
an entire cycle of denudation is completed and the land-forms
smoothed down to a peneplain, so that the newer sediments become
laid down on an approximately level, plain-like, surface of older
rock-formations, the strata of which will, however, be separated
from those of the new-made formations by flagrant unconformity.

(5) Details.

In our own country excellent examples of the normal progression
and the normally associated phenomena are usually detected, as

well as examples of the two variants just noted. Of the normal

sequence, the progression from the time of deposition of the
Carboniferous Limestone through the time of the Pennine-Armorican
movement into Middle Jurassic time may be regarded as quite
typical, but numerous other examples will at once suggest them-
selves. We may consider the normal succession in a little fuller
detail.

“SS

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixvil

(a) ‘Thalassic Period.’

(1) So long as deeper-water (‘thalassic’) deposition is taking
place, the extent and depth of water is sufficient to allow of the
wide dispersal of sediment before it finally reaches and subsides
upon the sea-floor, and hence the areas of similar sediment
deposited will be wide. This is abundantly proved by soundings.
In these circumstances each lamina in such a deposit must answer
to a single sea - floor, and be approximately contemporaneous
throughout its entire horizontal extent. These lamine will,
therefore, correspond with time-planes. Their outer margins will,
however, grade into organic, and their inner margins into coarse
sedimentary, deposits. In the deposits of the outer margins
correlation by organisms, if carried progressively from point to
point, ought not to present very serious difficulties.

Whether any evidences of still more profound ocean-depths,
in the form of oceanic or abysmal deposits, occur among British
strata has been a subject of considerable discussion. For a reason
to be stated later, such deposits are not to be expected on an
extensive scale in Britain. It has been maintained that some of
the radiolarian cherts are not truly abysmal deposits, but it is
noteworthy that these rocks are practically free from terrigenous
material.

(6) ‘Deltaic Period.’

(2) As uplift proceeds it not only elevates the land but brings
the floor of the area of deposition nearer to the surface of the sea.
Denudation becomes more active, and the amount of coarse detritus
carried out and deposited in shallow water increases in quantity.
Serious mistakes in correlation must inevitably result if the ‘ strata’
thus laid down are interpreted in the same way as in a deeper-water
deposit. We know of no means by which sand can be spread out
under water simultaneously over large areas, so as to form a sheet
contemporaneous throughout. Even during the depression of the
estuarine phase, while the area is expanding, the deposit will
grow landwards and gradually envelop the submerged land-form ;
thus the inner or landward parts will be the newer. During
uplift, again, when the area of deposition is contracting, two things
will occur :—(i) The deposit will travel outwards and seawards
from its margin, and the outer parts will be the newest; (i1) those
portions of the deposit nearest land, and therefore the first to
feel the uplift, will be subject to denudation, and will be partly
broken up and redistributed as a new deposit farther out to sea.

Ixvili PROCEEDINGS OF THE GEOLOGICAL SOCIBTY. [May 1911,

Since the thickest part of such an accumulation is, from the
nature of the case, the part most liable to destruction, it must
follow that the thickest parts of stratified masses now preserved
do not afford unequivocal evidence of the exact position of sea-
margins. The phenomena of aggregation and erosion under the
conditions postulated explain for us the lenticular deposition and
the amount of contemperaneous erosion which characterise such
sediments as those parts of the Silurian rocks that were formed
during periods of uplift. These characteristics have been brought
out by the researches of Dr. Herbert Lapworth in Central Wales
and by Miss Elles and Mrs. Shakespear on the Welsh Border. |

In view of the fact that planes along which occur the sediments
actually deposited in one and the same limited period of geological
time—true time-planes, as contrasted with theoretical or con-

ventional time-planes—must cut through many kinds of sediments
in deposits formed under these circumstances, it is evident that
they will not be throughout strictly coincident with the lithological
divisions known as stratification. It is, therefore, necessary from
time to time to re-examine any of the bases of our correlation
in which shallow-water deposits may be concerned. ‘Thus, in
tracing the variations of the Lower Oolites from the Cotswolds
into Lincolnshire and Yorkshire, a most useful summit-line has
been found and utilised in the Cornbrash, which is continuous in
its presence and characters from one end of the country to the
other. But it is improbable that this Cornbrash formation, one
of typical shallow-water aspect, could by any possibility have been
deposited contemporaneously throughont the whole of this area.
It has served an important stratigraphical purpose in initiating
correlation ; but the formation itself must almost of necessity be
progressively older when traced in one direction or another through-
out its extent. Unfortunately, J. F. Blake did not live to express
the conclusions to which his study of the Cornbrash fauna was
leading him. x
(c) ‘Terrestrial Period.’

(3) While uplift is in progress, the tectonic structures that are
being produced will be submitted to the denuding action of the sea,
which is likely to give to the whole smooth, plane-like, outlines.
But, so soon as there is emergence, the denuding agencies will
begin to adjust themselves to the growing structures, and diversity
in relief will be the consequence. The deposits now formed will
tend to accommodate themselves to this relief. For brevity,
they are here designated ‘terrestrial deposits.’

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixix

Whatever irregularities there may have been in the accumulation
of the shallow-water deposits of the preceding phase, they will be
intensified in the terrestrial deposits which are laid down in this
succeeding phase of uplift, and they will be correspondingly difficult
to correlate and arrange in order of time. Screes and gravels—
the result of frost and torrent action, and even sands formed in the
air, must necessarily be pushed outwards from their sites of origin ;
and if, during this outward migration, sheets of such materials
originate, it is clear that the different parts of any one of them
must be of different dates.

To a smaller extent the same is true of lacustrine deposits, and
there must be an outward progression from the shores towards the
deeper parts of these water-holding basins.

The materials deposited during the phase of uplift show a
tendency towards one of two extremes ; they are characterised either
by their angularity, or by the great amount of corrasion which they
have undergone. Débris broken up in the air, whether accumu-
lating in air or water, whether carried directly by gravitation, by
land-slips, or by ice, tends to retain its sharply broken edges. But
water-transported matter carried by high-velocity streams becomes
exceptionally well-rounded, and material fine enough to be carried
by wind becomes smoothed and polished.

Prof. Charles Lapworth has drawn attention to the fact that one
of the physiographical results of orogenic movement, accompanied
by denudation, is the tendency to intensify the production of longi-
tudinal valleys. There is observable in the Alps, and probably
elsewhere, a similar connexion between earth-moyement and the
formation of breccias. Excessive formation of screes and landslips
is found to be associated with the outcrop of thrust-planes. In the
quickened denudation brought about by the steep slopes thus
maintained there may possibly be found one explanation of the
frequent association of breccias with mountain-building.

Torrent-formed gravels are shot down immediately at the foot of
mountain-land, whether this abuts on sheets of water or on areas
of flat sediment recently formed or newly lifted. The first-formed
mass of gravel alters the conditions of slope and{velocity, and
successive loads are carried farther and farther outwards until
they reach gentler slopes or stiller water, and are perforce deposited
there. Thus the mass grows outwards from the area of denudation,
each increment being laid down against the preceding one on the
surfaces that we know as planes of ‘ false bedding.” These planes
are, therefore, the true ‘time-planes’ of contemporaneous deposit

ex PROCEEDINGS OF THE GEOLOGICAL sociETy. {| May rgI1t,

in the mass, and they must necessarily make an angle with the
upper and lower surfaces of the mass as a whole when its formation
is completed.

Neither the upper nor the lower surface of the ‘ bed’ so formed
will be a true time-plane. Its lower surface will be in contact
with the floor on to which the deposit has been pushed outwards,
and, therefore, will be of decreasing antiquity when followed
outwards from the area of denudation. As the ‘floor’ may be
receiving fine-grained deposit (for instance, air-borne or laid down
in a lake), portions of this finer-grained deposit will be contem-
poraneous with parts of the pebble-deposit. Thus the ‘ time-planes’
will pass down through the pebble-deposit into the finer-grained
‘bed’ beneath. On the other hand, the top of the ‘ bed’ is con-
ditioned by slope and stream-velocity ; and, where pebble-deposit
ceases at any point, it may be succeeded there by the laying down
of fine-grained material (except along the actual stream-courses),
each part of which, in its turn, will be synchronous with some part
of the pebble-deposit on the outer margins. ‘The ‘ time-planes’
will, therefore, here pass up into the overlying fine-grained deposit.

Thus, while it may be convenient to map such masses of pebble-
+beds’ as single units, and even to think of them as individual
‘formations, erroneous conclusions will inevitably follow unless it
is clearly realised that they are, in the main, units of structure,
texture, and condition, rather than of time. In converting the
record yielded by them into terms of time, it is essential in most
eases to ascertain their exact conditions of formation, and to be
guided by these in interpreting their structures and relationships.

From the variable and intensely localised conditions which
determine the accumulation of ‘ terrestrial’ deposits, it must follow
that formations originating thus will be lenticular and irregular in
their distribution, while means of correlation by organisms will be
of the scantiest and the most unsatisfactory nature. Breccias formed
by weather-action, or by glaciers in one part of the area, may be
contemporaneous with pebble-beds, gravels, and alluvia in another,
with lacustrine sediments or even with wind-drifted sands or loess
elsewhere. Delicate correlation in the case of such deposits as
those to which I have just alluded will probably always be a matter
of no little difficulty.

In connexion with these deposits, it is instructive to study
not only the work of W.T. Blanford and Sir Arthur McMahon
in Central Asia, but to consult also the more recent work of
Mr. W. R. Rickmers in that region.

Wael: 67: | ANNIVERSARY ADDRESS OF THE PRESIDENT. Bex

If it should happen that the lines of maximum uplift have been
so situated as to cut off rain-bearing winds from the lower-lying
lands, so that desert conditions arise, then denudation due to inso-
lation and frost will be so rapid—compared with chemical action—
that there will be little decomposition of the more stable minerals.
Only the more soluble ingredients will be removed from the
minerals most easily broken down, and the detritus mechanically
transported will consist of fresh and unweathered minerals. This
has been well demonstrated by the observations of Prof. Judd on
the Nile muds, and by those of Dickson and Holland on the glacial
muds of the Alps. It has also been found that the coarser detritus
in such deposits as the Triassic skerries formed round the wind-
smoothed rocks ef Mountsorrei and other Leicestershire areas is in
a precisely similar condition.

At the same time, the salts that are dissolved are often not
carried outside the area of inland drainage, but are deposited in
the lakes and pools, or thrown down as crusts upon, or cements
among, the materials of the drier areas. The latter must often
take place where the water-bodies have outlets which lose them-
selves in the sandy and desert areas. It is possible that the
dolomite crystals found by Dr. Cullis and Mr. Bosworth in the
Keuper Marls may, in part, have some such origin.

(d) ‘Estuarine Period.’

(4) There will, as a rule, be a sharp contrast between the fea-
tures produced when uplift is taking place, and those which are in
existence when re-submergence follows the terrestrial phase. The
tectonic structures that are being formed are all submitted to the
rasping action of marine erosion as they rise; and the emergent
land consists in part of planed folds, and in part of flat or gently
inclined sediments. But during the terrestrial phase the rock-
structures are dissected by subaérial denudation, originating features
of lively relief which, on submergence, will cause corresponding
diversity of contour. The rising coast will be one of sea-flats and
deltas, the subsiding coast one of gulfs and estuaries.

Fiat areas of completed erosion and planes of lacustrine, desert,
or loess, deposition will, on submergence, be the first to receive new
sediments. The edges of these deposits will creep up to the
uneroded mountain framework, and will pass rapidly into shallow-
water and marginal sediments. As submergence proceeds there
will be rapid overlap of coarser by finer material, each sheet of
which will, however, be edged by its coastal representative. Such

Ixxil PROCEEDINGS OF THE GEOLOGICAL society. [May 1911,

coastal deposits furnish us with the most precise data that we possess
concerning the physical changes of the period of subsidence, and it
is very unfortunate that it is just this class of deposits which is
most susceptible to destruction and removal later in its history.

When, after partial or complete submergence, old high lands
have again become resistant high land, there is a great tendency
for streams to grow between them and their enwrapping sediments.
It is here that the marginal and coastal types of sediment will
occur, and hence there will be considerable risk of their ultimate
destruction and disappearance. The Severn, the Dee, the Ouse,
and the Trent have robbed us of many valuable data which might
have given us better knowledge of the local geography throughout
the whole of Mesozoic times. But fortunate chances in the Mendips
and South Wales, in Devon and the Eden Valley, in parts of Shrop-
shire and in Charnwood Forest, have left precious relics of marginal
deposits of many ages, from Llandovery up to Cretaceous times.
At these isolated spots the facts enable us to extend in ima-
gination the margins of Mesozoic and earlier seas against the
older land- masses, and allow us to assure ourselves that the
science of paleogeography is not so hopeless as some would have us
believe. We have the old pebble-beaches, the screes, the cavern
and fissure-deposits, the washed-off vegetation and land-dwellers,
and, in certain cases, of which those already discovered are perhaps
only a foretaste, considerable areas of the enveloped landscapes.

In the case of old high lands, which after complete burial have
failed to re-emerge from their enveloping sediments, more con-
tinuous evidence is in existence; though. from the nature of the
ease, it is more rarely recoverable. Our knowledge in such cases
is limited to facts collected from borings and to inferences drawn
from the conditions of exposed deposits earlier or later in date.
Of the former our growing knowledge of the Armorican massif is
an excellent type; while of the latter Prof. Kendall’s utilisation
of the variation and the relations of the Jurassic and Cretaceous
sediments of the Eastern Midlands to infer the extension and
continued instability of the Charnian axis is a brilliant example.

(e) ‘Thalassic Period.’

(5) The deposits of a ‘ thalassic’ period succeeding a period of
uplift demand only passing notice. The successive encroachments
of the sea bring an increasing proportion of fine-grained and
organic deposits, with partial and (it may be) complete envelopment
of the old land-areas.

Mol. 67. ANNIVERSARY ADDRESS OF THE PRESIDENT, lxxill

(6) Examples.

The simple and stately progression of events thus outlined, from
depression to uplift and back again to depression, can rarely
be exemplified in completeness from the succession of British
Formations. There are necessarily many checks, variations in
the rate of movement, and alterations in both rate and type of
deposition. Thus, a movement of subsidence or of elevation has
rarely been uninterrupted by pauses, or even by reversal of
movement. The great Caledonian movement had at least three
periods of high intensity, with pauses and reversals. The
movement was at times so slow that it was overtaken by
deposition, while at other times deposits were swamped by its
rapidity. Besides this, as has been frequently pointed out, certain
classes of the deposits are especially liable to destruction during
submergence or emergence. When to this is added the possible
influence of isostasy, allowing the rapidly denuded land to rise and
the heavily loaded sea-bed to sink, the results of any particular
geographical phase become hard to follow and to link into a
connected scheme.

We may perhaps trace in the Coal Measures the influence of the
last-named cause. Although the story of the Carboniferous Period is
one of the shallowing of an area by upward movement, there are facts
which are best explained by occasional reversal. If we accept
the ‘ growth in situ’ theory of coal-seams, this contention needs no
further support, for the entire history of these strata would be
explicable by slow irregular subsidence, accompanied by deposition
sufficiently rapid to fill the hollows as fast or nearly as fast as
they were formed; while the coal-seams would be explicable as the
results of prolonged pauses in the general downward motion. Even
if we do not accept the theory of growth in situ, the overlap in
Britain of the Lower by the Upper Coal Measures is evidence of an
area of deposit temporarily expanding. That the movement was
not quite a simple one, however, but was accompanied by con-
siderable folding of the older Coal Measures, has been abundantly
proved by Mr. W. F. Clark in his new interpretation of the ‘Symon
Fault’ of the Coalbrookdale Coalfield. In a paper published in
our Journal he has shown that this phenomenon is not due to an
eroded valley as supposed by Scott, but to the planation of a series
of asymmetrical folds, on the denuded edges of which the newer
Coal Measures were subsequently laid down.

In our applications of Physiography to Geology we are not
VOL. LXVII. Vie

lxxiv PROCEEDINGS OF THE GEOLOGICAL socinty. | May rgrt1,

necessarily confined to dealing with statical conditions. We may
make use of our knowledge of the progression of events likely to
follow during the normal geographical development of the area.
of our study, to institute comparisons with the events recorded in
a continuous succession of stratified rocks. For example, I have
personally found my ideas of Carboniferous conditions clarified
after searching for like conditions or succession of conditions in the
present.

The Gulf of Mexico, with the Mississippi delta, the island of
Cuba, and the Caribbean Sea beyond, may be used to focus our ideas:
on a possible succession of events not unlike the progress of affairs
during the Carboniferous Period. At the present ‘time the region.
may be said to be passing through a Carboniferous Limestone phase.
We have («) a great northern river with its delta, (0) a central
sea, (c) an island to compare with the lowering ‘ Mercian High-
lands,’ and (d) the great ‘Culm’ depths of the Caribbean Sea..
Conditions at present favour the deposit of organic material over
vast areas in the region, the chief sediment coming in from the
Mississippi and building there a delta under conditions very similar
to those that prevailed when the Lower Carboniferous rocks of the
Scottish and Northern Pennine areas were being laid down.

Supposing that the geography of the region were to remain as:
at present, or if events were to be hastened by a general uplift of
the area, we should have a progression of phenomena not altogether
unlike those recorded in the Carboniferous strata of Britain, that
is, the gradual pushing out of the deltaic Coal-Measure conditions
from the northern continent and from the ‘ Mercian’ island.
Everywhere the deltaic conditions will be preceded by a marine
sediment of the type of the Millstone Grit ; and, where conditions.
favour it, the actual Coal-Measure conditions may be locally fore-.
shadowed in this deposit. The ‘ Millstone Grit’ type of formation
will be homotaxial throughout, it will represent the persistence of
a condition, it will rest everywhere upon organic deposits, and will
in turn be succeeded by deltaic Coal Measures. But neither it nor
any member of the Coal-Measure sequence, except perhaps the
coal-seams themselves, will be, as a whole, a true time-unit; in
some places it will be of the same age as part of the organic deposits,
in other places it will be contemporaneous with the formation of
parts of the Coal Measures.

Another example may be drawn from the known progression
from the Ordovician to the Old Red Sandstone. The British
Ordovician geography finds its nearest modern parallel in the:

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT Ixxv

‘Festoon Islands’ of the Western Pacific, with their active
volcanoes, their steep slopes and profound depths, their sheltered
and land-locked seas. The different types of Ordovician strata
and volcanic rocks may be matched in the deposits which are now
forming there. The continuance of upward movement in the
Festoon Island region of the present would produce in the first
instance ‘mediterranean’ seas of Silurian type, and, ultimately,
land-locked lakes similar to those in which the Old Red Sandstone
originated. Some of the boundaries of the lakes, like those of the
Old Red Sandstone lakes, would have the structures of newly-
developed orogenic units; while others would consist of older
land-masses which have been modified to a smaller extent by the
new movement. .

I do not put forward these instances as perfect analogies, but I
do believe that the imagination is stimulated by such comparisons,
and that if one tries to visualise existing circumstances more
thoroughly, one is more likely to look out for points of resemblance
and difference between the present and the past, and to observe
with greater acumen, or to criticise more unsparingly, the facts
which such important and interesting rock-systems as these
present for our observation. It will, of course, only be after the
study and rejection of a number of instances that anything like
satisfactory comparisons will be effected; and in nearly all
instances we shall only reach a complete mental picture by
combining conditions from many different areas. But the success
that has so far rewarded this method affords encouragement in the
task of examination and selection, and gives us reason to hope that
the study of existing physiography and physiographical causes will
prove in the future, as in the past, the master-key with which to
unlock the secrets which Geology still holds for us. |

(7) Need for New Geographical Work.

It is in coin of this denomination that the Geologist looks to the
Geographer to repay part of his debt to Geology. Our science has
given to Geography much to which its recent progress is due. The
structure of the rock-masses of which land-forms are built up, the
adjustment of denuding agencies to that structure, the existence
in the past of causes now no longer in operation, and of alien
structures, long since removed, but the influence of which may still
be traced; all these and many other aids have been given to
Geographers in their attempt to explain land-forms.

f2

lxxvi PROCEEDINGS OF THE GEOLOGICAL society. {May 1911,

If the Geographer wishes to repay some of this debt, it may be
suggested to him that we, for our part, require far more detailed
observations on such results of particular geographical phases, under
varying climates and in,different parts of the world, as are likely
to throw light on the method of formation of the rocks, But
neither the observations made nor the record of them are likely to
reach the utmost possible value to the Geologist, unless the
Geographical observer possesses a practical knowledge of the actual
difficulties which confront the Geologist. The observer in deserts
should be equipped with some knowledge of those strata which
by some are supposed to have been formed under desert conditions,
so that he may be on the look-out for points of resemblance or
dissimilarity. The observer of volcanoes will be of far more use to
us if he knows something of the nature and position of con-
temporaneous and intrusive rocks, as laid bare in some of our great
areas of dissected volcanic groups. The estimation of the denuding
action and other work of the British rivers now being carried out
by the research department of the Royal Geographical Society is a
good illustration of the type of work desired.

To the Oceanographer and the marvellous work accomplished
by him during the latter half of the last century, we are deeply
in debt. He has discovered vast areas of slow deposit of previously
unexpected materials in the profound depths of the ocean, and
quickened us in our search for truly abysmal deposits among the
strata. But we would now ask him for much more detailed
observations of those prosaic terrigenous sediments which line
our shores and compare so closely with the deposits that make up
the bulk of the geological record. The great value of the results
obtained from the Funafuti borings, not half of which have yet
been fully utilised by geologists, give some inkling of what may

reasonably be expected when geographical observers with a geological

grounding are able to make a detailed study of the shallower-water
deposits that everywhere fringe the land-areas.

(8) Palzeogeography.

While we owe to Ramszy the most striking of the early attempts
to picture for us certain of our phases of paleogeography, it was
Clifton Ward and Prof. KE. Hull who endeavoured to express the
facts with regard to British deposits upon maps. ‘They have been
tollowed by Mr. A. J. Jukes-Browne, whose work on ‘ The Building
of the British Isles’ has been of great service in making it possible

aes

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Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxvil

to visualise and remember the leading phenomena of stratigraphical
geology, and to group together numbers of facts and inferences
with which it was previously most difficult to retain touch. But

‘this is not all that we owe to the authors and followers of the

method. Such maps systematise future research, they direct us to
the places where the discovery of new facts is desirable, and they
enable each new fact to be utilised in checking, establishing, or
modifying, conclusions expressed by provisional lines on the maps.

It was only natural that this branch should advance with rapid
strides in Britain, because this country has done so much detailed
work, not only in the study of its own constituent formations, but
also in the mapping of their extent of outcrop. There are other
reasons also of which we should not lose sight.

(a) Methods of Investigation.

In order to obtain what Dr. Marr has called the ‘geogram’ of a
formation in its greatest perfection, we require to know the entire
extent of its variations, not only along its outcrop, but in that part
which is hidden from sight; and we ought to be in a position
to infer the probable variations in that almost equally important
part. which has been destroyed by denudation.

The study of the outcrop has in many cases proved of great
service—because important variations, such as those of the Lower
Jurassic rocks, have been detected and worked out along the line
of strike. But the outcrop evidence decreases in value whenever
it happens that denudation has left, as in the case of the Chalk,
an outcrop which follows a condition line or condition strip of the
area of deposition.

It is here that, in my opinion, insufficient use has been made
of the ‘isodiametric lines’ which Prof. Hull drew attention to,
and utilised to bring out the south-eastward thinning of the
Mesozoic rocks. We look to the projected Memoir of the Geological
Survey on the thickness of the British formations, which Fox-
Strangways began and Mr. I’. V. Holmes is carrying on, to give us
information whereby it may be possible to draw such lines through-
out the British strata. We may be able to deduce from such lines
not only much information with regard to the laws of distribution
of ancient sediments, with consequent inferences on their sources
and boundaries, but also some indication of the nature and extent
of ancient denudation. It is even possible that the lines may be
found to bear relationships with contemporaneous sagging and

Ixxvilll PROCEEDINGS OF THE GEOLOGICAL socipry. _[ May 1911,

elevation, and with tectonic structures and movements subsequently
produced, and thence even with lines of drainage.

Information on the buried extension of strata 1s more difficult to
obtain, and it can only be got when folds or faults have broken the
course of the regular structure, allowing the agents of denudation
to lay bare a far larger sequence of formations than usual, or where
deep drilling has been carried out. ‘There is perhaps hardly a single
deep boring in the country which has not yielded important in-
formation as to the variation of some stratum or other in a direction
not coincident with its outcrop. Evidence is given of the thinning
and disappearance of strata, of their change in grain, in organisms,
and in relation to. beds above and below. Whether these borings
succeed or fail in their primary economic purpose, their value to the
geologist is incalculable ; and I would again urge, as on more than
one previous occasion, that the information which they give should
be preserved with the most jealous care. Not only detailed and
tabulated records, but actual rock-specimens should be collected
and kept; and, even though the information yielded may have in
some cases to be locked up in confidence for a generation or more,
that information will eventually be available for generalization.
The confidence engendered by the administration and personnel of
the Geological Survey has, I am glad to say, borne abundant fruit in
this direction, and we may trust that an increasing flow of records of
this invaluable information will continue to be stored in the Survey
Office for the use of present and future geologists. It is even to be
hoped that at some future time, both for economic and for purely
scientific reasons, borings may be carried out at carefully selected
spots, not only to elucidate underground structure and its bearings
upon the distribution of deposits of economic value, but even to
settle doubtful points of scientific interpretation.

The part of any formation which extends and is hidden beneath
the sea presents even greater difficulties, and it is improbable that
we shall ever possess more than inferential information about the
large area of the earth’s surface covered by the hydrosphere. It is
true that lines of borings have been carried out across narrow and
shallow seas, and a daring success was made of the lagoon-boring
at Funafuti; but for the most part we shall have to obtain our
knowledge of the origin and history of the greater features of the
earth from observations made upon what are land-masses at the
present time. Still, portions of areas which were until recently
covered by the sea, but the surfaces of which have been raised above
its level by deposits of drift, ice, coral, or other recent marine deposits,

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT, |xx1x

present inviting spots for deep borings, if funds could be found for
carrying them out, not only for economic but for strictly scientific
reasons. Thus, borings in the north of the Isle of Man, made in
search of salt-deposits, have revealed what was, until Pleistocene
times, part of the bed of the Irish Sea; and we can hardly avoid
speculating as to what would have been found if it had been prac-
tivabie to carry down the Funafuti boring twice as far as was
possible under the circumstances.

A consideration of the fact that each formation has been derived
from, and implies the destruction of, an equal mass of pre-existing
formations makes it evident that much of what would have been
extremely valuable in giving evidence of paleogeography has been
irrecoverably destroyed. Beyond the average line of outcrop of
each formation we oniy have left occasional fortunate extensions
of it, or just the stranded outliers which happen to have escaped
destruction. In the absence of these we are driven to do our
best with bits broken from the edges of the formations, which
may chance to have been embedded in later rocks and to be still
recognisable.

In default of other evidence, we may be guided by the principle
that parallelism in the bedding of closely associated strata implies
that any movement which may have occurred during their depo-
sition has been of an epeirogenic character. There may have been
advance or retreat of coast-lines, but no development of striking new
- structures. The physiographic features will remain approximately
parallel to one another during the time and at the place represented
by a series of conformable deposits. It is on this assumption that
we are able to draw inferences as to the probable position and
trend of the shore-lines of the Liassic Sea, based on our knowledge
of the extension of the Trias on the one hand and of the Lower
Oolites on the other. :

(>) Growth of Britain.

From fragments of evidence like this, hammered out bit by bit
by himself or by many other observers, Mr. Jukes-Browne has
made a brave struggle to picture for us the stages of geography
through which Britain has advanced to its present configuration,
its successive ‘ lines of growth,’ and the normal and critical periods
of its evolution.

That so much success has rewarded the attempt is to some extent
due to the nature of the area chosen. Britain, though at the present
time the north-western outpost of the European continent, has not

\k

]xxx PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1911,

received the sediments that build up its formations from that con-
tinent. It has, on the other hand, grown in the main south-eastwards
since Paleozoic times, from the more ancient Laurentian land-mass
on the west. What may have been the original extent, composition,
or outline, of this land-mass we do not and perhaps can never know
for certain; but it seems to have begun to undergo denudation in
Torridonian times, and to have been gradually disintegrated until
a mere wreck in the north-west of our Islands is all that is now
left of it. Wave after wave of movement from the eastward has
broken against the old continent, or off its edge, shore-line after
shore-line has formed farther and farther eastwards: the present
great northern plain of Europe representing the deeper sea into
which the finer sediments were swept. Thus in Britain the
deeper-water and finer-grained sediments are the least common, and
the lithological facies of our formations is mostly coarse-grained,
shallow, shoreward, and even terrestrial. This it is which has
invested them with so much of exceptional interest, and has
stimulated among British Geologists the practice of reasoning in
the direction of paleeogeography.

Innumerable oscillations and even great orogenic movements have
occurred, varying the monotony of formational succession, but it
was long before the western land was completely broken down, the
newer features formed out of the relics of its earlier denudations
acting in a sense as groynes on which the destructive forces were
spent. The Caledonian movement first drew off the forces of
marine attack, denudation being mainly concentrated on the newly
formed and highly ridged mountains. Then followed the Pennine
and Armorican movements with corresponding effects, and, finally,
such minor elevations and dislocations as are due to the almost
spent force of the Alpine disturbance drove the forces of the attack
still farther to the east.

: (c) Movement and Infilling.

While, when acting on rocks which have not been affected by
previous movements, each distinct crust-movement in Britain has
imposed its own definite direction or directions, in other cases the
direction of older movements has been taken up again in the newer
rocks. Thus the strikes of the Carboniferous rocks of the Pennine
and Armorican regions are those of the trend of the local axes
of elevation characteristic of those movements. But the strikes of
those caught in the Central Valley of Scotland, in the Vale of Clwyd,

Wol;'67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. lxxxi

or in the Warwickshire Coalfield have been influenced by older
directions. In the same way the Charnian direction of movement
makes itself felt not only in the Cambrian rocks of Nuneaton, but
also in the later Carboniferous rocks. Similarly, the Armorican
direction has made itself felt in the Wealden Arch and in the
London Basin.

The directions of movement are convincingly betrayed by the
first infillings of terrestrial and lacustrine sediments which follow
closely upon the movement. Very significant in this respect is the
position of the main Torridonian outcrop. Still more definite is
the evidence of the lines that border the Old Red Sandstone areas,
of which enough is preserved, as shown by Sir Archibald Geikie,
to give a fair idea of the position and outline of the lakes of this
period. Almost equally striking is the run of the outcrops of
the Permian and Triassic Systems, flanking the Pennine, running
down to the Bristol Channel, and forming a tongue along the main
syncline of North Devon.

The infillings of the New Red Sandstones, followed by the rest
of the Mesozoic deposits, are particularly instructive. We find that
they occur in three types of localities :—

(i) Flanking the features produced by the immediately preceding
movements, and best preserved on the east side of them. Also in
the minor synclines of those movements.

(ji) In the ‘lee’ area which often occurs between the rocks
affected by the immediately preceding movement and the firm land
of an earlier movement. The New Red Sandstones flanking the
west of the Pennine and extending into the Irish Sea exemplify
this position.

(iii) In the rejuvenated folds of still older rocks—for instance, in
the vales of Eden, Dee, and Clwyd, in the rift-valley off Western
Scotland, and in the Irish loughs such as Carlingford, Belfast,
Larne, and Foyle.

The areas of deposition in our own islands thus tended to become
increasingly complex as one movement succeeded another. 7

The study of the chief British movements makes it clear that in
that region, at any rate, the distinction between orogenic and epeiro-
genic movement is a question rather of degree than of kind. The
so-called ‘ orogenic ” movements have been accompanied by sharper
folding and faulting and the production of marked relief; the epeiro-
genic by the uplift of broad anticlinal curves, and by denudation
over large areas of comparatively small thicknesses of sediment, and
that for the most recently deposited. Among the typical orogenic

Ixxxll PROCEEDINGS OF THE GEOLOGICAL soctpry. [May 1grt,

movements the chief are the earlier and later stages of those move-
ments with Caledonian trend and that of post-Carboniferous times.
Of epeirogenic may be noted the middle portion of the Caledonian
movement, that in the late Carboniferous, that which closed the
Jurassic Period, and that great uplift which came at the end of
the Cretaceous.

But there were many gentle movements which we are only now
beginning to appreciate, and doubtless many others of which we
shall gain information later on by the application of the methods
that have proved so successful in the hands of Mr. 8. 8. Buckman,
Mr. L. Richardson, and others, in the study of the Jurassic rocks. In
this case the minute zoning of the Bajocian rocks has shown clearly
that the local thinning of the strata so frequent along the outcrop
of the Inferior Oolite is correlated with the absence of particular
faunas, and presumably of the strata which should contain them.
This may be due to one of two main causes—(a) the absence of
the strata owing to non-deposition or subsequent erosion, or (3) the
migration and substitution of faunas. xhaustive examination of
the fossils indicates that the former explanation is more likely to
be the satisfactory one; and that this is the case seems to me to be
proved by the fact that at the junction-line, to which attention 1s
called by minute zone-working, signs of erosion and of pause in
deposition are usually visible in the form of irregular surfaces,
borings by worms and mollusca, and by deposits of oysters or of
rolled fragments and broken organisms. Further, the correlation
of series of localities indicates progressive absence of increasing
thicknesses of rock in definite directions. The directions thus indi-
cated correspond with the position of minor folds in the subjacent
or superjacent rocks. So there is every probability that these
areas of erosion have been determined by slight but long-continued
local uplift of anticlinal nature, affecting well-marked areas and
culminating along definite lines.

Results apparently similar are coming out from the zoning work

in Lower Carboniferous rocks, and it is interesting to compare

these with the latest interpretation of the ‘Symon Fault,’ to which
attention has already been directed. That such results do not yet
appear to have been reached in the zoning of the Chalk may be
partly due to the thickness of the zones into which that Formation
is at present divided, or, which is more likely, to the Chalk having
been formed under water so much deeper than most other British
organic formations, that the elevatory movement was not sufficient
to bring the area within the scope of denudation. On the other

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. Lexi

hand, movement may have been in comparative abeyance during
this part of the Cretaceous Period; but this is so unlikely that 1

am disposed to accept the second hypothesis.

If that explanation be the true one, we must look upon the
Mesozoic as a period, not of rest, but of quiet epeirogenic movement
of a pulsatory character. The evidence obtained from the ‘ non-
sequences” in the Jurassic rocks would seem to indicate that the
oolitic limestones were deposits of an exceptional nature in a sea
which was clear, shallow, and favourable for life, rather than deep ;
and that the clays of this System were formed in deeper water than

the alternating limestones. If this be the case, we are driven a stage

farther back to some more remote explanation of those alternations
which are so striking and tenacious a feature of the British strata
between the Inferior Oolite and the Portland Beds. By what
means was denudation so much quickened that even the deeper
waters of the period of marine advance became loaded with fine-
grained sediment over such wide areas? Was it merely the
exposure at certain periods of material that was more easily
denuded into fine mud; or is it not more likely that the climate
may have varied periodically, and that denuding forces were corre-
spondingly quickened and retarded ?

(qd) Recurrence of Type in Cycles of Deposition.

Marcel Bertrand, in a most suggestive and illuminating memoir,
endeavoured to correlate the successive types of deposit preceding and
following the movement periods of different dates with one another.
In this he obtained considerable success, but in some instances, it
seems to me, he rather strained the facts to bring them into con-
formity with his ideas of recurrence. Such recurrence is certainly
traceable throughout the British record, but it is generally overlaid
with differences so striking that the interference of other causes
with a different periodicity must be suspected. This statement will
become clearer when we examine a few examples and exceptions.

The remarkable resemblance of the sandy sediments of the

‘Torridonian, the Old Red Sandstone, and the New Red Sandstone

is a commonplace in British descriptive geology.

The Torridonian and Old Red Sandstone breccias, probably
associated with maximum uplift, may be correlated with the
Brockrams and the other Permian breccias.

The well-rounded pebble-beds of the Bunter constitute a type
which we see anticipated in both Torridonian and Old Red Sand-
stone conglomerates, and followed to a certain extent by those of

IXxxiv PROCEEDINGS OF THE GEOLOGICAL socieTY. [May 1911,

the Lower Greensand, but more definitely by the Nagelfluh of the
Alps.

The deltaic deposits of the Upper Carboniferous are copied by the
Estuarine deposits of the Lower Oolites, and by both the Wealden
and the Oligocene deposits, although it is not easy to point to any
forerunners quite comparable with them.

The British Rheetic type of deposit is not altogether unlike the
lowest Carboniferous in Scotland and the Upper Eocene in Southern
England.

The Flysch of the European Alpine regions may be compared
with the uppermost Silurian and with the problematical and
difficult rocks of the Permo-Carboniferous.

The graptolitic shales of the Lower Paleozoic are to some extent _
copied by the clays of the Jurassic and Cretaceous.

+

(e) Variability and Non-Recurrence.

But in every case there are differences which go far to mask the
primitive resemblances. The likeness is perhaps strongest in the
Pebble-Beds with their exquisite rounding, their method of occur-
rence, and to some extent the nature of their material; but the
Breccias differ in their massiveness, in the nature of the fragments
contained in them, and in the relation of the latter to the rocks
exposed to denudation at the time when they were formed. The
Rheetic types of deposit vary in the smoothness and wide extent of
the deposition areas, in the slowness or otherwise of the incursion
of sea-water and marine organisms, and in the amount of oscillation
which the area was undergoing. The Flysch-like deposits bridge
over periods of movement of varying length, and form a barren
type of deposit which encroaches upon different parts of one or
more Systems. They differ from one another according to the
duration and balance of conditions of shallow sedimentation ruled
by uplift and contemporaneous erosion. The Red Beds may or
may not be accompanied by deposits due to chemical reaction or
precipitation. The Shales and Clays agree in the fineness of their
sediment and in the presence of pelagic organisms; but they differ in
consequence of the nature, depth, and extent of the great hollows
of the sea-bed in which they were laid down—in some cases perhaps
comparable with great ocean-depths, in others with those of smaller
land-locked basins.

But the most profound difference is perhaps that seen between
the Coal-bearing strata and any correlative deposits that may

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxxv

occur in our area. ‘These sandstones, shales, ganisters, fire-clays,
bituminous shales, coals, cannels, and ironstones occur in Britain
on two main levels in the Carboniferous rocks; but they are never
repeated again on anything like the same scale in our British
formations. The nearest approach to them is to be found in the
Lower Oolites of Yorkshire ; but there is, as it were, some slight
attempt at recurrence also in the Tertiary rocks. More than this,
it is a remarkable circumstance that more than half of the coals
of the Northern Hemisphere are of Carboniferous age.

Croll, in associating the Glacial Epoch with astronomical causes
and their influence on atmospheric circulation, has claimed that
the physical configuration of the Atlantic Ocean may have had a
secondary influence, in that by its peculiar outline it permitted of
important variations in the oceanic circulation of the North
Atlantic. Mr. A. R. Wallace has further pointed out that, coin-
ciding with these conditions, there possibly occurred an elevation of
North-Western Europe which may have allowed the land there to
take advantage of the anomalous conditions of solar distance, axial
direction, and oceanic circulation, to favour the accumulation of
snow on the flanks of the North Atlantic Ocean. According to this
suggested modification of the theory, the combination of several
causes was required to bring about the remarkable phenomena of
that most eventful epoch in our geological history.

It appears to me that a not less remarkable concatenation of
events may have been required to produce a Carboniferous Period of
the extent, duration, and importance of ours ; a Period to which this
country owes so much of its commercial and political pre-eminence,
In the first place, there was required a wide area of sea gradually
filling up with an unfailing supply of sediment brought by rivers of
depth and power. It was further requisite that the sediments
should be deposited with great regularity over the large area of a
delta in wide flat sheets which seem, as though through isostatic
conditions, to have been built up to the level of the sea, not once or
twice but frequently, throughout fully the half of a great Geological
Period. The deposition must have been accompanied by subsidence
not regular but intermittent, with rest-intervals of sufficient lengt}.
to allow of the growth of swamp vegetation for the varying but
lengthy periods necessary for the accumulation of material sufficient
to make seams of coal ranging from 2 to 30 feet in thickness. The
vast area covered by some of these coal-seams has been compared
with that of the forests on some of our modern tropical or sub-
tropical swamps and deltas; but it must be confessed that no exact

Ixxxvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. | May tort,

present-day representative of the growth and preservation of car-
bonaceous matter on the scale of the Coal-Measures has yet been
found. The nature of the vegetation must have been such that it
could spread and flourish under the peculiar swamp conditions that
prevailed, and yet be suitable to provide the class of material which
would give origin to coaly matter. Last, but not least, the climate
must have been such as to encourage rapid growth of rank vege-
tation; yet it must have allowed, in place of ordinary decay, a
decomposition capable of permitting the storage of the numerous
hydrocarbons which go to make up the coal.

Several of these conditions may have occurred more than once
during geological ages in single localities and for short periods
of time, and to this must be due the lignite seams of several
of our formations. But the coincidence of them all and for the
enormous period of time comprehended by the strata of our Coal-
Measures is likely to be only a rare event; and it is remarkable
that, during the Jurassic Period in Britain, there should be so near
an approach to a recurrence of the conditions necessary to make a
valuable coalfield.

The study of our British Coalfields seems to show that, even with
the conditions so highly favourable as they were in our area, the
most favourable conditions of all were concentrated in particular
and limited regions. Tracing such a seam as the Thick Coal of
South Staffordshire towards the border of its area of deposition,
we find it rapidly passing into irregular and worthless carbonaceous
sediment. Tracing it away from this line, we find it passing into its
most concentrated and highly valuable condition. Beyond this, its
constituent seams become divided and spread apart by the inter-
vention of wedges of sediment which thicken out towards the
north. Others of the coal-seams take on similar changes until,
as Prof. Charles Lapworth pointed out in his valusble report
to the Coal Commission, the ccal-seams of North Staffordshire are
contained in three or four times as much mechanical sediment as
in the South Staffordshire Field.

In the same way, at approximately like distances from the
southern land-barrier, the coal-seams of the Warwickshire Coalfield
undergo a like change from south to north. Thus there would
appear to occur, even in the regions of favourable sedimentation, a
condition of things approximately parallel to the coast-line, capable
of giving origin to a concentration of vegetable accumulation,
correlated perhaps with less and more steady and regular move-
ment than elsewhere. Mr. Wade has published evidence from the

Vol. 67.| ANNIVERSARY ADDRESS OF THE PRESIDENT. lxxxvil

Lancashire and Cheshire Coalfield which appears to point in the
same direction.

I think that we may conclude from this example, which is typical
of many, that cases of recurrence in our cycles of deposition are not
likely to occur with frequency or exactness; but that under the
complexity of causes which operate to impart to the strata their
dominant characters there will probably be cases of reinforcement
or interference which will give to each cycle, and each phase of a
cycle, its individual characteristics.

Although in Britain we have cause to be grateful for a System
like our Carboniferous, which provides us with so wide a range
of products of economic value, we must acknowledge that our
country has but an insignificant place in a table showing the world’s
distribution of native petroleum. But when we pass into the chief
regions where petroleum is obtained, we must be struck by the
restriction in its distribution. The problem of that distribution
is complicated by the fact that, while coal remains stationary in
the beds among which it was formed, petroleum can migrate, like
water, from one formation to another ; and the beds in which it is
now stored may be separated considerably from those in which
it originated. Even then, however, it tends to occur in rocks of
rather restricted range. The constant association of petroleum,
- when indigenous in the rocks in which it now occurs, with the
anomalous deposits which we associate with inland lakes and
closed continental areas, gives a strong suggestion that the origin of
petroleum is to be sought, not so much in special chemical reactions
influencing chance organisms that may be preserved in rocks, as
in a concurrence of the several special geographical conditions
regulating the nature of the deposition and the existence and pre-
servation of life-forms at certain phases of earth-history.

(9) Other Effects of Earth-Movement.

The intensity of the results of the successive movements gives
the impression that it is related to their antiquity ; but it is
certain that intensity is, in reality, related to the distance of any
part affected from the main focus of action. The folding, thrusting,
and cleavage of the Charnian rocks and the disturbance and
cleavage of those of the Longmynd appear to have been effected in
pre-Cambrian times. In the latter case, the ring of Cambrian, a
later sediments remains unaffected by cleavage.

‘The more severe effects of the movements with Caledonian trend

i

Ixxxviil PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1911,

spread outwards from the famous overthrust region of the North-
West Highlands of Scotland, and the more central region marked
by the recumbent folds recently described by Mr. Bailey. How
much of the metamorphism is attributable directly to the move-
ment, to the association of intrusive rocks with the movement, to
the original condition of the rocks, or to the thermal conditions
under which the movement was carried on, is at present an
unsettled question. The intensity of the movement diminishes
when traced through the Southern Uplands into the Lake District
and again into North Wales; even here it is accompanied by
thrusting and cleavage. ‘The latter affects Silurian as well as
Ordovician and Cambrian rocks, but it is not known to affect
anything newer. Mr. Harker has shown that in Carnarvonshire
the location of the cleavage can be connected with the presence of
hard, old, masses of resistant rock; it is remarkable that the
Longmynd has not produced like results in its neighbourhood. It
may be argued that the pressures had here considerably diminished.
A similar absence of cleavage is evident in the Nuneaton Cambrian
rocks, despite the presence of the Charnian mass.

The Pennine movement has been restricted in its effects to the
production of folds and faults without cleavage or overthrust; but
the Armorican movement proper at its maximum intensity has
been enough to produce the gneisses and schists of Britanny and of
Devon and Cornwall. All later movements have resulted in
nothing more serious than a certain amount of folding and faulting,
crushing, thinning out, and occasional overthrust.

The connexion of vulcanicity with earth-movement has long
been recognised, and is being more fully illuminated by the active
petrographical research that is now going on. Lach period of
orogenic movement in Britain has been connected with one or
more of the phases of extrusive or intrusive action, volcanoes,
plutonic intrusion, or minor intrusion. So far as the composition
of the rocks is concerned, as Mr. Harker has pointed out, the
Pacific type dominates over the Atlantic type. The igneous action
tends to occur on the margin of the great Atlantic continent, to
break through the older rocks where the cover is thin or absent,
and to be associated with regions in which contemporary or
posthumous folding is asserting or about to assert itself. Thus the
dominance of the Pacific type of rocks may possibly be connected
with the general dominance through British geological history
of geographical features of ‘ Pacific’ rather than ‘ Atlantic’ type.
The exceptions will probably be explicable when we possess a

Vol. 67.] ANNIVERSARY ADDRESS OF THE PRESIDENT. [xx xix

more complete knowledge of the detailed succession and nature of
the movements of each period.

So far as time is concerned, extrusive igneous action has been
associated mainly with the close of geosynclinal conditions, while
intrusive, and particularly plutonic, activity has been connected
with the formation of geanticlines and orogenic uplift. The
variation which shows itself in the products of a single petro-
graphical province seems to be, in the main, due to differentiation ;
and we owe to Mr. G. Barrow and Mr. A. Harker the valuable
suggestion that one of the chief determining factors in the progress
of differentiation is the action of varying pressures on a magma in
a state of partial or of potential fluidity. This suggestion, though
not yet fully worked out, promises to be a most fruitful one, and
holds out hopes of establishing a closer relationship than has
hitherto been possible between the structures of the earth-crust
and the nature and distribution of igneous material in connexion
with it.

Mr. Finlayson has recently attempted to work out the relation
between the periods of earth-movement and the formation of
ore-bodies. He finds that only a small proportion of our metalli-
ferous veins date back to the Caledonian or earlier movements, but
that the great period of vein-filling was associated with the
post-Carboniferous movement, even in areas where the country
rocks are of Ordovician or of Silurian age. Ores found in post-
Carboniferous rocks have in most cases been deposited there by
redistribution, concentration, and enrichment from earlier deposits.
If he is right in his contention, he has given to the Later Paleozoic
Era a further claim on our gratitude for its contributions to the
mineral wealth of our country. -

The connexion is probably only indirect between the several
movements which have affected the British Isles and their present
systems of drainage and consequent relief. While the Wealden
dome is drained by a system of rivers that dates to the Alpine
movement, and the Thames and Solent valleys are consequent on
structures due to that movement, phenomena apparently similar
in Wales, Lakeland, and the Pennine Chain cannot be similarly
linked with older movements. The number of submergences and
planations, the covering with sediment and the subsequent
removal of it, have probably destroyed or buried lines of drainage
due to earlier movements, and such relationships as still subsist
are due to that adjustment of drainage to structure which must
always work itself out eventually, on whatever lines it may make

VOL, LXVII. g

X¢ PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1911,

its start. It is doubtful whether, in any case, we can go back
farther than the great Chalk covering for the initiation of the
earliest of our existent drainage-lines, and even drainage initiated
in Tertiary times has in many cases suffered serious modifications
during the latter part of that Hra.

(10) Earth-Movement and Life.

There can be little doubt that a biological reflexion of the
changes in physical geography of even a small area like our own
country will be found in the progress of its life, if this is definitely
looked for by paleontologists. Just as, locally at any rate,
unfavourable circumstances have certainly retarded or shifted the
direction of evolution, so the coincidence of a number of favourable
features must exercise a stimulating influence upon it. But the
case must necessarily be much complicated by the action of other
factors in the physical environment, and the reactions of organisms
upon each other.

As an example, we may take the point made by Starkie Gardner
when he showed that one of the most potent factors in mammalian
development must have been the coming into existence of grasses
and herbage plants. These had a physical reaction upon the
formation of soil and in modifying the course and extent of
denudation, while biologically they gave a great impetus to the
development of the Herbivora. But the extensive development of
these plants coincided with, and was partly dependent upon, the
production of wide and suitable plains on which there could be
established savannahs replacing many of the forests and swamps.
Following on this came a fresh impetus to the development of
migratory habits associated with power of speed, which in its turn
gave an impulse to the evolution of animals of gregarious habits on
the one hand and of hunting habits on the other.

There are two essays which, even at this late date, are well
worth considering in this connexion. One is the Presidential
Address delivered to this Society by Huxley in 1870, in which he
dealt with evolution in geological time and the relation of
successive faunas to one another. ‘The other is a paper by Searles
V. Wood, Jun., published in 1862,* of the existence of which Huxley
was unaware when writing the Address just mentioned.

In the latter the author endeavoured to supply a physical
explanation in the first place of the exaggerated development of

1 Phil. Mag. vol. xxiii, pp. 161-71, 269-82, 382-93.

Vol. 67." ANNIVERSARY ADDRESS OF THE PRESIDEN. x¢i

reptiles during Mesozoic times, and in the second place of the
rapid diminution of these forms and their replacement by mammals
in the Tertiary Era. The first he attributed largely to the peculiar
physical features which characterised the Mesozoic geography, the
second to the remarkable changes in these features initiated by
the Tertiary revolution. Although the exact conditions of physio-
graphy which were postulated by the author will hardly stand in
the light of our present knowledge of these geographies, the essay
is of extraordinary interest and importance in, thus early, directing
attention to the bearing of physical changes on problems of the
evolution of life. :

The earth’s surface is the theatre of two types of change :—Those
which are external and comprise chiefly the influence of the sun
upon the air, land, and water; and those which are internal and
depend on earth-movement, The last may be attributable entirely
to the activity of the interior, or possibly may be in part due to the
influence of external bodies, such as the sun and moon, as well. ‘To
a large extent these two sets of influences must be independent.
We can grasp the possibility of a world’s population evolving under
the influence of either of these suites of conditions acting in the
absence of the other. But, if the two are acting together, the
results will become of a much more highly complex character,
because with two independently acting variables there must neces-
sarily be periods of coincidence and of interference in the effects
produced.

We should expect, in these circumstances, that epochs of relative
acceleration and retardation of evolution would occur with a
certain amount of apparent irregularity in period, complicating
very considerably the otherwise steadfast advance in life.

Such striking differences as the outline, trend, contour-plan, and
latitudinal extension of the New World in contrast with the
Eurasian continent; or the remarkable difference between the
Atlantic and Pacific Oceans in their coasts, depths, and structures,
will illustrate my meaning. And we have to recognise that differ-
ences probably as marked as these have swept over the places
now occupied by single continents and oceans in different stages of
their history.

In the distribution of animals and plants at the present day
there is found recorded many of the physical changes that the
lands which they have inhabited have undergone. Is it too much
to hope that we may one day recognise, stored up in the organi-
sation of the creatures themselves, and in their ancestral history

xcil PROCEEDINGS OF TAE GEOLOGICAL SOCIETY. [May 1911,

a record of the physical factors which have been one of the im-
pelling causes of their evolution ?

In this branch of enquiry, however, the paleogeography of a
single region, even when it embraces a whole country whose past
geological conditions have been so varied and typical as our own,
is inadequate to the strain of all-embracing generalisations ; and
the study of a whole continent, or, better, of the world itself as
a whole, is essential before it will be possible to reach a true
conception of the physical machinery which has been operating in
evolution.

A corresponding world-wide outlook is also requisite when we
wish to place in correct perspective the physical development of a
limited area in association with the evolution of the physical
features of the world as a whole. The more important strati-
graphical works, like those of Sir Archibald Geikie in Britain, A. de
Lapparent in France, and Chamberlin and Salisbury in America,
have summarised for us the world-geology of the different Periods,
from which we can obtain a general conception of the broad
outlines of the geography of large areas of the world at different
times. Salisbury and Willis for America, and de Lapparent for
the whole world, have endeavoured to express in the form of maps
the known geological facts that bear upon the geography of the
different Periods. Even here, however, there is the serious
handicap that two thirds of the earth’s surface are covered by sea
and inaccessible to observation.

But there is a vast amount of work still to be done in filling
in the details of even the land portion of these maps, and each part
so filled in will inevitably diminish the difficulties left in extending
the lines in the areas into which our observations do not or cannot
extend. It is only by work of this description, by obtaining a
fuller and deeper knowledge of the whole of the events recorded in
our strata throughout the world, that we shall ever approach the
solution of the larger and more fascinating problems of Geology.

(11) Conclusion.

In conclusion, we may sum up some of the main points which
have been touched upon. The History of the Earth, so far
as the Geologist is capable of following it through the geological
systems and formations, is a history of successive geographies,
and of the relations of those geographies to the living beings
which successively characterised them. In the reading and

Nal. 67:2] ANNIVERSARY ADDRESS OF THE PRESIDENT. XClll

restoration of those geographies there is but one unfailing guide,
unceasing comparison, at every stage, of the ascertainable geological
phenomena of the past with the known geographical phenomena ot
the present. But, in following that guide, every step must be made
with the greatest caution and circumspection. It is not sufficient
to recognise alone the fact that the succession of geological systems
and formations is representative, on the whole, of geological time ;
but we must recognise the fact that each individual formation
must be studied as a lithological unit, its local place and limits in
time accurately fixed, and its time-equivalent elsewhere determined.
In this task we meet at every stage on the one hand with un-
expected difficulties, and on the other with unexpected interpretative
geographical parallels. This gives to our work the interest of
novelty and the charm of unceasing discovery, and to eaeh one
of us may come in turn the personal satisfaction of having contri-
buted some new factor or some new generalisation to the History
of the Earth.

XCIV PROCEEDINGS ©F THE GEOLOGICAL society. [May 1911,

February 22nd, 1911.

Prof. W. W. Warts, Sc.D., M.Se., F.R.S., President,
in the Chair.

Augustus Hamilton, Director of the Dominion Museum, Welling-
ton (New Zealand); and Thomas Herdman, B.Sc., The Grove,
Alston (Cumberland), were elected Fellows of the Society.

The List of Donations to the Library was read.

The following communication was read :—

‘The Geology of the Districts of Worcester, Robertson, and
Ashton (Cape Colony).’ By R. H. Rastall, M.A., F.G.8.

Baron Furencz Norcsa, Jr., then gave some account of the
Geology of Northern Albania. He said that he had examined
the greater part of the Province of Skutari in Western Turkey, and
recognized three distinct structural units: namely, the North
Albanian platform, the folded Tsukali, and the eruptive region of
Merdita. In the first region Mesozoic limestones of all periods
predominate ; in the second region Mesozoic radiolarian chert is
found ; while in the third region Mesozoic clastic rocks, volcanic
tuffs, and eruptive masses are abundant. The first and third units
are not folded, but are, at least in part, overthrusts from the north
and south respectively above the second (intermediate) unit, which
is strongly folded. In Northern Albania Upper Carboniferous and
Permian rocks are also distinguishable, and there is an Hocene
Flysch.

The following specimens and lantern-slides were exhibited :—

Rock-specimens from the Worcester and Ashton districts of Cape
Colony, exhibited by R. H. Rastall, M.A., F.G.8., in illustration of
his paper.

Rock-specimens and fossils from Northern Albania, and lantern-
slides, exhibited in illustration of Baron F. Nopesa’s remarks.

‘Head of a man’ in flint, from a gravel-pit at Beaconsfield
(Buckinghamshire), exhibited by J. Allen Howe, B.Sc., F.G.S.

oe

March 8th, 1911.

Prof. W. W. Warts, Se.D., M.Sc., F.R.S., President,
in the Chair.

James Ford, The Woodlands, Mold (North Wales) ; and Thomas
Harris Burton, Farnsfield (Nottinghamshire), were elected Fellows
of the Society.

The List of Donations to the Library was read.

Vol. 67. | PROCEEDINGS OF THE GEOLOGICAL SOCIETY. XCV

The PrestpENrt announced that the Council had awarded the
Proceeds of the Daniel Pidgeon Fund for 1911 to Trussrn1an
Cuartes Nicnonas, B.A., Trinity College, Cambridge, who proposes
to investigate the relations of the older rocks in the Lleyn Pen-
insula (Carnarvonshire).

The following communications were read :—

1. ‘Contributions to the Geology of Cyrenaica.’ By Prof. J. W.
Gregory and others.

(i) The Geology of Cyrenaica. By John Walter Gregory,
D.Sc., F.R.S., F.G.8., Professor of Geology in the University
of Glasgow.

(ii) Notes.on the Kainozoiec Mollusca of Cyrenaica. By
Richard Bullen Newton, F.G.S.

(iii) Foraminifera, Ostracoda, and Parasitic Fungi from
the Kainozoic Limestones of Cyrenaica. By Frederick
Chapman, A.L.S., F.R.M.S.

(iv) The Fossil Echinoidea of Cyrenaica. By John Walter
Peoresory, Wise, EURS., B:G-S.

(v) The Foraminiferal Limestones of Cyrenaica. By
David Paterson MacDonald, M.A., B.Sc.

2. ‘On the*Teeth of the Genus Ptychodus, and their Distribution
in the English Chalk.’ By George Kdward Dibley, F.G.S.

The following specimens, lantern-slides, and maps were
exhibited :—

Rock-specimens and fossils, microscope-sections and lantern-
slides, exhibited by Prof. J. W. Gregory, D.Sc., F.R.S., F.G.S., in
illustration of the paper on Cyrenaica.

Mollusca and other fossils from that country, exhibited by
R. B. Newton, F.G.S., in illustration of the same paper.

A series of teeth of Ptychodus from Kent and Surrey, exhibited
by G. E. Dibley, F.G.S., in illustration of his paper.

Specimen of Ptychodus decurrens Ag., from the Chalk Marl of
Glynde, north-east of Lewes, exhibited by Dr. A. Smith Woodward,
Heke tels.poee.G.8.

Geological Survey of Scotland: 6-inch Map of Lanarkshire,
Sheet 7, N.W.,S.E., & S.W. (Solid & Drift), 1910, presented by
the Director of H.M. Geological Survey.

xevl PROCEEDINGS OF THE GEOLOGICAL society. {May ort.

March 22nd, 1911.

Prof. W. W. Warts, Sc.D., M.Sc., F.R.S., President,
in the Chair.

Ernest Parsons, B.Sc., 13 Colville Terrace, Beeston Hill, Leeds,
was elected a Fellow of the Society.

The List of Donations to the Library was read.

The following communications were read :—

1. ‘On some Mammalian Teeth from the Wealden of Hastings.’
By Arthur Smith Woodward, LL.D., F.R.S., F.L.S., Sec.G.S.

2. ‘Some Observations on the Eastern Desert of Egypt; with
Considerations bearing on the Origin of the British Trias.’ By
Arthur Wade, B.Sc., F.G.S.

3. ‘Faunal Horizons in the Bristol Coalfield.” By Herbert
Bolton, F.R.S.E., F.G.S.

The following lantern-slides and specimens were exhibited :—

Lantern-slides exhibited by Dr. A. Smith Woodwara, F.R.S.,
F.L.S., Sec.G.S., in illustration of his paper. Also specimens
exhibited by C. Dawson, F.S.A., F.G.8., in illustration of the same.

Rock-specimens, minerals, and fossils from the Eastern Desert of
Egypt, with microscope-sections and lantern-slides, exhibited by |
A. Wade, B.Sc., F.G.S., in illustration of his paper.

Fossils from various faunal horizons in the Bristol Coalfield,
exhibited by H. Bolton, F.R.S.E., F.G.8., in iliustration of his
paper.

April 5th, 1911.

Dr. C. W. Anprews, B.A., F.R.S., Vice-President, —
in the Chair.

Frank Elgee, 23 Kensington Road, Middlesbrough ; and Morgan
David Williams, 28 Morlais Street, Cardiff, were elected Fellows
of the Society.

The List of Donations to the Library was read.

The following communications were read :—

1. ‘Trilobites from the Paradoxides Beds of Comley (Shrop-
shire).’ By Edgar Sterling Cobbold, F.G.S. (with Notes on some
of the Associated Brachiopoda, by Charles Alfred Matley, D.Sc.,
Gs):

a a ee a ll eee eee

Vol. 67.] PROCEEDINGS OF THE GEOLOGICAL socipry. X¢Vli

2. ‘The Stratigraphy and Tectonics of the Permian of Durham
(Northern Area). By David Woolacott, D.Sc., F.G.8.

The following specimens, lantern-slides, and maps were ex-
hibited :—

A series of trilobites and brachiopoda from the Comley Para-
doaides Beds, and lantern-slides, exhibited by E. 8. Cobbold,
F.G.8., in illustration of his paper.

Specimens of Paradowides groomit Lapw., exhibited by Prof.
Charles Lapworth, LL.D., M.Sc., F.R.S., F.G.S., in illustration of
Mr. .Cobbold’s paper.

Rock-specimens and fossils from the Permian of North Durham,
with two geological models and several lantern-slides, exhibited
by Dr. David Woolacott, F.G.S., in illustration of his paper.

Geological Map of the Pre-Quaternary Systems of Sweden,
1: 1,500,000, by A. E. Tornebohm & others, 2nd ed. 1910; Das
Spatglaciale Sud-Schweden: Uebersichtskarte mit Osen, End-
moranen & Schrammen, 1: 500,000, by Gerard de Geer, 1910;
and Map of Land-Forms in the neighbourhood of the great Swedish
Lakes, 1: 500,000, by Sten de Geer, 1910, presented by the
Director of the Geological Survey of Sweden.

April 26th, 1911.

Prof. W. W. Warts, Sc.D., M.Sc., F.R.S., President,
in the Chair.

The List of Donations to the Library was read.

The PrestpEnr made the following announcement :—

‘ By the decease of Prof. Thomas Rupert Jones, F.R.S., in his 92nd year,
the Geological Society has lost one of its oldest and most valued members,
who was formerly (1850-1862) Assistant Secretary of the Society, and Editor
of the Quarterly Journal. During his long life Prof. Rupert Jones was an
ardent geologist and paleontologist, and has left behind him in the Palzeonto-
graphical Society’s Memoirs, in the Quarterly Journal of the Geological
Society, in the ‘Geological Magazine,” and in the ‘‘ Annals & Magazine of Natural
- History ” no mean record of his abilities and strenuous labours. Nor was his
work confined to original papers, but as Hditor of the Quarterly Journal of
the Geological Society, the “‘ Geological Magazine,” the “ Reliquize Aquitanice,”
Dixon’s ‘Geology of Sussex,” the ‘ Arctic Manual,” and other works, he
showed a high-class capacity in literature.

‘Never in receipt of more than a very moderate income, derived from a
small pension upon his retirement from the post of Professor of Geology in
the Royal Military College, Sandhurst, he was unable to make any suitable
provision for his death (when his pension ceased), and has left a widow with
two daughters and an invalid son, almost wholly unprovided for.

‘It is proposed to form a Committee of Geologists to consider the means of
providing some memorial in aid of the widow and daughters of the late
Professor. Any Fellows present willing to assist in this object are requested
to communicate with the Assistant Secretary.’

VOL. ExVil. h

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Ria ont ARR A Ie VIABLE NATUR IETS SIT Game ena CET Ee tes 2

X¢Vlil PROCEEDINGS OF THE GEOLOGICAL socinry. f[Aug. fort,

The following communication was read :—

‘The Llandovery and Associated Rocks of North-Eastern Mont-
gomeryshire.’ By Arthur Wade, B.Sc., F.G.S.

Dr. J. D. Fatconnr, M.A., F.G.S., then gave an account of the
Geology of Northern Nigeria, illustrating his remarks by
means of lantern-slides. He pointed out that the Protectorate of
Northern Nigeria covers an area of about 255,000 square miles,
over half of which crystalline rocks are exposed at the surface. A
series of hard banded gneisses of an Archean type is intermingled
with a series of quartzites, phyllites, schists, and gneisses of sedi-
mentary origin, in such a way as to suggest that the two series,
while originally unconformable, have been at a later period affected
by a common folding and foliation along axes which are pre-
dominantly meridional in direction. The two series have also been
pierced by numerous_igneous intrusions of a granitic type, which
are subdivided into (1) an older, wholly or partly foliated group,
and (2) a younger non-foliated group, characterized by the pre-
dominance of soda-bearing types.

Folded and faulted rocks of Cretaceous age are found in the
valleys of the Benue and the Gongola. They consist of a lower
series of sandstones and grits, in places salt-bearing, and an upper
series of limestones and shales with numerous fossils of Turonian
age. These Cretaceous rocks are overlain unconformably by a
horizontal series of sandstones, grits, conglomerates, and ironstones,
which in Sokoto province contains intercalations of Middle Eocene
limestone. Considerable volcanic activity occurred during Tertiary
times, and gave rise to extensive fields of basaltic lava in Bauchi
and Bornu, as also to numerous puys of trachyte, phonolite, olivine-
basalt, and nepheline-basalt throughout Southern Bauchi, Muri,
and Yola. Repeated minor oscillations of the crust occurred during
the latter part of the Tertiary Era, and culminated in the elevation
of the Bauchi plateau, the depression of the Chad area, and the
establishment of the present river-system.

In addition to the lantern-slides above mentioned, the following
exhibits were shown :—

Rock-specimens, fossils, microscope-sections, and lantern-slides,
exhibited by Arthur Wade, B.Sc., F.G.8., in illustration of his
paper.

Drawings and models, exhibited by Oswald H. Evans, F.G.S., to

- illustrate the gliding flight of the Arch@opteryz.

Worked flints obtained from gravels overlying Tertiary limestones,

near Campeche (Mexico), exhibited by Leonard Y. Dalton, B.Sc.,
Gis:

wel. 67. PROCEEDINGS OF THE GEOLOGICAL SOCIETY. XC1x

May 10th, 1911.

Prof. W. W. Warts, Se.D., M.Sc., F.R.S., President,
in the Chair.

Herbert Stanley Bion, B.Sc., Assistant Superintendent, Geo-
logical Survey of India, Calcutta; J. S. Freeman, Buckfastleigh,
Church End, Finchley, N.; Harman Milton, 23 Sussex Place,
Regent’s Park, N.W.; Rowland Edgar Nicholas, F.L.S., Bitterne
Park (Hampshire); Harold Hyde Ridsdale, Kelfield Lodge, Streetly,
near Birmingham; and Edwin Taylor, B.Se., Lecturer in Physical
Science in the Consett Technical Institute, Lennel House, Blackhill,
were elected Fellows of the Society.

The List of Donations to the Library was read.
The following communications were read :—

1. ‘The Lower Carboniferous Succession in the North-West of
England.’ By Prof. Edmund Johnston Garwood, M.A., Sec.G.8.

2. «The Faunal and Lithological Sequence in the Carboniferous
Limestone (Avonian) of Burrington Combe, Somerset.’ By Prof.
Sidney Hugh Reynolds, M.A., F.G.S., and Arthur Vaughan, M.A.,
DSe.,:F.G.S.

Mr. S. Hazzieprine Warren exhibited a piece of worked wood,
possibly the point of a paleolithic spear. It measured 157 inches
in length and 14 inches in thickness ; one end had been carefully
fashioned to an acute point, the other end was broken. Mr. Warren
said that he had quite recently dug it out of an undisturbed part
of the freshwater deposit of Clacton-on-Sea. This deposit yields
remains of Hlephas antiquus, Rhinoceros, and other Pleistocene
mammalia in abundance, as also paleolithic flint-implements, some
of which were now exhibited. The contemporaneity of the pointed
shaft-—with the Pleistocene deposit in which it was found—was
confirmed by the fact that it agreed in condition with the wood
that is extremely plentiful in the same bed. It also had calcareous
encrustations upon its surface, such as were seen on other remains

from this deposit.

In addition to the specimen above described, the following
exhibits were shown :—

Fossils, rock-specimens, microscope-sections, and lantern-slides,

exhibited by Prof. E. J. Garwood, M.A., Sec.G.S., in illustration of

his paper.
Fossils, rock-specimens, microscope-sections, and lantern-slides,

exhibited by Prof. 8. H. Reynolds, M.A., F.G.S., and Dr. A,
Vaughan, M.A., F.G.S., in illustration of their paper.

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C PROCEEDINGS OF THE GEOLOGICAL socieTy. {Aug. rofl,

May 24th, 1911.

Prof. W. W. Warts, Sc.D., M.Sce., F.R.S.,,President,
in the Chair.

The List of Donations to the Library was read.

The Names of certain Fellows of the Society were read out for
the first time, in conformity with the Bye-Laws, Section VI,
Art. 5, in consequence of the Non-Payment of the Arrears of their
Contributions.

The following communication was read :—

‘On the Geology of Antigua and other West Indian Islands, with
Reference to the Physical History of the Caribbean Region.’ By
R. J. Lechmere Guppy. (Communicated by Prof. E. J. Garwood,
M.A., Sec.G.8.)

Prof. W. J. Porr, M.A., F.R.S., gave a demonstration of new
processes of colour-photography, as applied to Mineralogy
and Geology, illustrated by a series of extremely beautiful lantern-
slides.

The demonstration was followed by a Discussion, in which the
Presipent, Dr. J. J. H. Tratz, Prof. E. J. Garwoon, Prof. J. W.
Jupp, Dr. J. W. Evans, and Mr. G. W. Youne took part, and to
which Prof. Popx replied.

The following exhibits were shown :—

Fossiliferous Millstone Grit from the Drift of Hertford, exhibited
by A. H. Willams, F.G.S.

‘Implement’ from (?) Carisbrooke (Isle of Wight), exhibited on
behalf of Mr. F. Morey, by A. W. Oke, B.A., F.L.S., F.G.S.

June 14th, 1911.

Prof. W. W. Warts, Sc.D., M.Sc., F.R.S., President,
in the Chair.

Reginald Cooksey Burton, B.Sc., 84 Princes Street, Bishop Auck-
land, and Armstrong College, Newcastle-on-Tyne ; George Hogben,
M.A., Inspector-General of Schools in New Zealand, Wellington
(N.Z.); Tressilian Charles Nicholas, B.A., Trinity College, Cam-
bridge; Ernest Sheppard Pinfold, Undercliff Cottage, Bradford ;
Ira Cyril Frank Statham, 71 Hednesford Road, Heath Hayes,

Vol. 67.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. el

Cannock (Staffordshire) ; and Henry Crunden Sargent, Ambergate
(Derbyshire), were elected Fellows of the Society.

The PresipENT announced, with a regret which he was assured
all the Fellows would share, the unexpected decease at Karlsbad
of Prof. Victor Karu Untie, University of Vienna, who was to have
been balloted for as Foreign Correspondent.

The List of Donations to the Library was read.

The Names of certain Fellows of the Society were read out for
the second time, in conformity with the Bye-Laws, Section V1,
Art. 5, in consequence of the Non-Payment of the Arrears of their
Contributions.

The following communications were read :—

1. ‘On a Monchiquite Intrusion in the Old Red Sandstone of
Monmouthshire.’ By Prof. William 8. Boulton, B.Sc., Assoc.R.C.S.,
HG:S.

2. ‘ Notes on the Culm of South Devon: Part [—Exeter District.’
By Frederick George Collins, F.G.S.; with a Report on the Plant-
Remains by E. A. Newell Arber, M.A., F.G.8., and Notes on the
Cephalopoda, by George C. Crick, Assoc. R.S.M., F.G.S.

The following specimens, maps, etc. were exhibited :—

Hand-specimens, microscope-sections, photographs, and lantern-
slides, exhibited by Prof. W. 8. Boulton, B.Sc., Assoc.R.C.S., F.G.S.,
in illustration of his paper.

Fossils, rock-specimens, and lantern-slides, exhibited by F. G.
Collins, F.G.S., in illustration of his paper.

Fossils exhibited by G. C. Crick, Assoc.R.S.M., F.G.S. (by per-
mission of Dr. Wheelton Hind, F.G.S.), for comparison with the
specimens exhibited by Mr. F. G. Collins.

A specimen of cleaved volcanic ash, showing some peculiar effects
of cleavage, one side of the specimen being three-quarters of an inch
thick, the opposite side thinning to a cutting-edge, and numerous
erystals of pyrite being elongated to three or four times their
width. From Homster Slate-Quarries (Cumberland), exhibited by
John Postlethwaite, F.G.S.

Twenty-four sheets of the 6-inch Geological Survey Map (Drift)
of England and Wales, presented by the Director of H.M. Geological
Survey.

aa Geological Institute of Hungary: Geological Map on the
scale of 1: 75,000—-Sheet Zone 22, Kol. xxix, Szaszsebes, 1909.
Presented by the Director of that Institute.

cil PROCEEDINGS ®F THE GEOLOGICAL socimTy. [Aug. IgII,

A Sprcran GENERAL Muerine was held before the Ordinary Meeting
at 7.30 p.M., in order to consider the following resolutions :—

(1) That the contents of the Geological Society’s Museum, with the
exception of those marked A, which are conspicuously displayed in the
Society's Apartments, be offered to the Trustees of the British Museum
(Natural History), and to the Director of the Museum of Practical Geology
(Jermya Street).

(2) That the Council be instructed to offer the British specimens to the
Director of the Museum of Practical Geology, and the Foreign and
Colonial specimens to the Trustees of the British Museum (Natural

History).

(3) That, in the event of the acceptance of both gifts, the Council be
empowered to transfer the collections to those two Institutions, in
accordance with the conditions which have been provisionally arranged.

(4) That the Treasurer be authorized to expend a sum not exceeding
£250, in adapting the space thus vacated by the Collections for the
purposes of the extension of the Library.

Resolution (1) was passed by 29 Ayes to 1 No, and Resolutions
(2), (3), and (4) were passed nemine contradicente.

It was stated that, in accordance with Resolution 4 passed at the
Special General Meeting on January 25th, 1911, and confirmed at
the Annual General Meeting on February 17th, the Council had
approached the Trustees of the British Museum (Natural History)
and the Director of the Museum of Practical Geology, and under-
stood that they were willing respectively to accept the parts of the
Collections mentioned in the foregoing resolutions, under the con-
ditions set out as follows :— :

All type-specimens and figured specimens, and all material of exceptional
value and importance in illustrating the advance of Geology, as registered in

ublications and especially in publications of the Society, are to be retained by
the British Museum and the Museum of Practical Geology respectively.

But, when the Officers of these Museums have had ample time to work
through the Collections, there will probably remain a considerable amount
of material which it would not be necessary for the Museums to retain
permanently. The Officers of these Museums will draw up a report specifying
any proposed disposal of such material, and present it to the Society for its
approval. The Council will furnish the two Museums with copies of the
letters which have been received, containing requests for gifts of duplicate and
other material. While desiring that such requests, and others that might be
subsequently made, should receive consideration, the Society will doubtless
have no wish to restrict the action of the Officers of the two Museums in this
matter, but will repose entire confidence in any action which they may see fit

to take.

The list of specimens marked A, to which reference was made in
Resolution (1), is here given in full :—

Specimens illustrating the Alluvial Gold-Deposits of New South Wales. Pre-
sented by Sir Daniel Cooper.

Canis palustris, from the Upper Miocene Freshwater Limestone of CEningen
(Switzerland). Presented by Sir Roderick I, Murchison,

Vol. 67.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. ciil

Ichthyosaurus, from the Lower Lias of Barrow-on-Soar (Leicestershire).

Skull of Ichthyosaurus platyodon Oonybeare, from the Lower Lias of Lyme
Regis. Presented by several Fellows of the Society—unnamed.

Iehthyosaurus intermedius Conybeare, from the Lias of Lyme Regis. Presented
by Sir Henry T. De la Beche.

Pentacrinites briareus, from the Lias of Lyme Regis. Presented by Sir Henry
T. De la Beche.

Tree-Section.

Portion of Trunk of an Oak, from the Submarine Forest near St. Leonards-
on-Sea. Presented by Sir Woodbine Parish.

Part of the Silicified Trunk of a Coniferous Tree (Cedroxylon), from the
Purbeck Beds, Isle of Wight. Presented by John Fisher.

Ammonite (Haploceras lewesiense Mantell, sp.) from the Chalk of Tusburgh
(Norfolk). Presented by John Wright.

Two ammonites (over doorways).

Paramoudra, Upper Chalk, believed to be from near Norwich (Norfolk).

Paramoudra, Upper Chalk, Norfolk. Presented by the Rev. J. Gunn.

Two specimens of Cervus megaceros from a peat-bog, Ireland.

Rhinoceros tichorhinus, King’s Newnham, near Church Lawford (Warwick-
shire), Presented by Dean Buckland.

Two specimens of Bison priscus, one from Walton (Essex), presented by J. T.
Wetherell.

Two skulls of Bos Jongifrons (over doorways).

Tusk of Mammoth (Hlephas primigenius), from Siberia.

Tusk of Elephant, said to be from the Forest Bed (Norfolk).

Slab of Wenlock Limestone with Periechocrinus moniliformis, Favosites, aud
other fossils, from Dudley (Worcestershire). Presented by the Earl of
Dudley.

Isle of Wight Greensand Section.

Meteoric Iron from Zacatecas (Mexico). Presented by Sir Woodbine Parish.

Meteoric Iron from Atacqma (Peru). Presented by Capt. Colquhoun & Joseph
Burkart.

Fulgurites from Drigg (Cumberland).

Les Eyzies (slab with worked flints and bones).

Model of Granite Veins (intrusive in schist), Galloway (Scotland).

Model of Arthur’s Seat and the King’s Park at Edinburgh, showing geological
structure, by J. Robison Wright.

Model of Mount Etna.

Model of Mount Vesuvius.

Columns of Basalt from the Giants’ Causeway (Antrim). Presented by John
Wiggins.

Glaciated” boulder from Scotland. Presented by Robert Chambers.

Quartz (in officers’ room).

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